HomeMy WebLinkAbout20102525.tiff Colorado Department of Public Health and Environment
Water Quality Control Division (WQCD)
Public Notice No. CO-11-10
Denver,Colorado October 22,2010
PUBLIC NOTICE OF TENTATIVE DISCHARGE PERMIT ACTION
Purpose.This notice states that the CDPHE intends to issue,deny,modify,revoke and reissue,terminate or reissue,
Colorado Discharge Permit System permits,pursuant to the Clean Water Act,and the Colorado Water Quality
Control Act. All permits are subject to the U.S. Environmental Protection Agency(EPA)review.
WQCD has made tentative determinations in conjunction with EPA that limitations and conditions imposed in these
permits implement all applicable statutes and regulations and water-quality standards.
Public Comment Period.Written comments or written requests for a public meeting on the tentative determination
are to be submitted to WQCD by November 21,2010. Also, written comments must be received by this date from
any person who believes the proposed actions have the potential to cause material injury to a water right.
Additional Information.The following information is available at the County Clerk and Recorder's office of
the county in which the proposed discharge is to occur or at the WQCD's office(contact Loretta Houk, 303-
692-3531): the draft permit,the permit application with all accompanying data; the name and address of each
activity regulated by the permit; a brief description of each applicant's activities,which result in a discharge;
the name and description of the waterway to which each discharge is made;name,address, and telephone
number of the appropriate District Engineer for the WQCD; and a description of the comments and hearing
request procedures. The mailing address for written public comments is—CDPHE,WQCD-P-B2,4300
Cherry Creek Drive South,Denver,Colorado 80246-1530. The website to view the public notice and drafts
can be located at http://www.cdphe.state.co.us/wq/PermitsUnit/index.html
Permit No. Applicant County
CO0000621 CF and I Steel LP Pueblo
Rocky Mountain Steel Mills
2100 South Freeway Pueblo
Action-Issuance—Renewal
Discharge—Arkansas River
CO0021571 Fowler Town of Otero
Fowler WWTF
200 Main St Fowler
Action-Issuance—Renewal
Discharge—Arkansas River
CO0023086 Snowmass WSD Pitkin
Snowmass WSD WWTF
0177 Club Drive Snowmass Village
Action -Modification— Amendment
Discharge—Brush Creek
CO002443I Eagle River Water&Sanitation Dist Eagle
Avon WWTF
950 W Beaver Creek Blvd Avon
Action-Issuance—Renewal
Discharge—Eagle River
PL , i1 /-"C 2010-2525
lo" 91 -Iv /0-n2°2-10
CO0029033 Royal Gorge Company of Colorado Fremont
Royal Gorge
4218 County Road 3A Canon City
Action-Issuance—Renewal
Discharge—Hanging Bridge Gulch
CO0037311 Eagle River Water&Sanitation Dist Eagle
Edwards WWTF
3101 Lake Creek Village Dr Edwards
Action-Issuance—Renewal
Discharge—Eagle River
CO0046370 Redstone Water and Sanitation District Pitkin
Redstone Water and San District WWTF
1091 Redstone Blvd Redstone
Action-Issuance—Renewal
Discharge—Crystal River
CO0047155 Gypsum,Town of Eagle
Gypsum WWTF
437-B Porphyry Rd Gypsum
Action- Revocation
Discharge—Eagle River
CO0048830 Gypsum,Town of Eagle
Gypsum WWTF
437-B Porphyry Rd Gypsum
Action-Issuance—New
Discharge—Eagle River
CO0048241 Eagle,Town of Eagle Eagle
Eagle Wastewater Treatment Facility
185 Violet Lane Eagle
Action-Issuance— New Permit
Discharge—Eagle River
CO0048445 Town of Erie Weld
Erie North Water Reclamation Facility
501 State Hwy 52 Erie
Action-Issuance— New Permit
Discharge—Boulder Creek
CO0048691 SWG Fountain Valley, LLC El Paso
Fountain Valley Power Plant
18693 Boca Raton Heights Pueblo
Action-Issuance—Renewal
Discharge--Fountain Creek
CO0048823 Ogilby Corporation Pitkin
DBA Avalanche Ranch Cabins&Antiques
Avalanche Ranch Geothermal Project
12863 Hwy 133 Carbondale
Action-Issuance— New Permit
Discharge —Crystal River
CO0046523 Penrose Sanitation District Fremont
Penrose Lagoon
0800 9th Ave
Action—Issuance—Renewal
Discharge—Bear Creek
Public Notice of Enforcement Settlement/Penalty Actions
Purpose of Public Notice: To solicit public comment on the proposed Expedited Settlement Agreement between
the Division and Big M Feedlot. This agreement will resolve civil penalties associated with Big M Feedlot's alleged
violations of the Colorado Water Quality Control Act identified through documentation provided to the Department
by Big M Feedlot dated May 28, 2010. Big M Feedlot operates a Concentrated Animal Feeding Operation in Weld
County. Division Contact: Kelly Morgan,(303)692-3634/kelly.morgan@state.co.us.
Purpose of Public Notice: To solicit public comment on the Division's intent to impose a civil penalty against
Sumo Development Company, Inc. for violations of the Water Quality Control Act and a stormwater permit for
construction. Sumo Development was involved in the construction of a residential subdivision in Fremont County.
Division Contact: Michael Harris,(303)692-3598/michael.harris@state.co.us.
Documents related to the above enforcement action are available for public inspection at the Division. Copies of the
above action are available upon written request to the Division. Public comments should be submitted by
November 21, 2010 and directed to CDPHE, WQCD-CAS-B2, 4300 Cherry Creek Drive South, Denver, CO
80246-1530.
COLORADO DISCHARGE PERMIT SYSTEM (CDPS)
FACT SHEET FOR PERMIT NUMBER CO0048445
TOWN OF ERIE NORTH WATER RECLAMATION FACILITY
WELD COUNTY
TABLE OF CONTENTS
I. TYPE OF PERMIT 1
II. FACILITY INFORMATION 1
III. RECEIVING STREAM 2
IV. FACILITIES EVALUATION 2
V. PERFORMANCE HISTORY 3
VI. TERMS AND CONDITIONS OF PERMIT 3
VII. REFERENCES 12
VIII. PUBLIC NOTICE COMMENTS 13
1. TYPE OF PERMIT Domestic - Major Municipal, Mechanical Plant, New Surface Water
11. FACILITY INFORMATION
A. SIC Code: 4952 Sewerage Systems
B. Facility Classification: Class B per Section 100.5.2 of the Water and Wastewater Facility
Operator Certification Requirements
C. Facility Location: Latitude: 40.0979 N, Longitude: 105.0432 W
D. Permitted Feature: 001A, following disinfection and prior to mixing with the receiving stream
The location(s) provided above will serve as the point(s) of compliance for
this permit and are appropriate as they are located after all treatment and
prior to discharge to the receiving water.
E. Facility Flows: 1.5 MGD
F. Major Changes From Last Renewal:
This is a new permit, and therefore there are no changes to discuss.
ISSUED EFFECTIVE EXPIRATION
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 2, Permit No. CO0048445
III. RECEIVING STREAM
A. Waterbody Identification: COSPBO10, Boulder Creek
B. Water Quality Assessment:
An assessment of the stream standards, low flow data, and ambient stream data has been performed to
determine the assimilative capacities for Boulder Creek for potential pollutants of concern. This
information,which is contained in the Water Quality Assessment(WQA)for this receiving stream(s), also
includes an antidegradation review, where appropriate. The Division's Permits Section has reviewed the
assimilative capacities to determine the appropriate water quality-based effluent limitations as well as
potential limits based on the antidegradation evaluation, where applicable. The limitations based on the
assessment and other evaluations conducted as part of this fact sheet can be found in Part I.A of the permit.
Outfall 001A will continue to be the authorized discharge point to the receiving stream.
IV. FACILITY DESCRIPTION
A. Infiltration/Inflow (UI)
As this is a new facility,no infiltration/inflow problems have been documented in the service area.
B. Lift Stations
Table 1V-1 summarizes the information provided in the renewal application for the lift stations in the
service area.
Table IV-1 —Lift Station Summary
% Capacity
Station Firm Pump *
Name/# Capacity (gpm) Peak Flows (gpd) (based on
peak flow)
Kenosha Farms 2 @ 600 gpm 48,000 gpd 5%
C. Chemical Usage
The permittee did not specify any chemicals for use in waters that may be discharged. On this basis, no
chemicals are approved under this permit. Prior to use of any applicable chemical, the permittee must
submit a request for approval that includes the most current Material Safety Data Sheet (MSDS) for that
chemical. Until approved, use of any chemical in waters that may be discharged could result in a
discharge of pollutants not authorized under the permit. Also see Part ILA.1. of the permit.
D. Treatment Facility and Capacities
The facility consists of mechanical screen and grit removal facilities, integrated fixed-film activated
sludge process including biological nutrient removal and secondary clarification, filtering and UV
disinfection. The pennittee has not performed any construction at this facility that would change the
COLORADO DEPARTMENT OF HEALTH, Water Qualify Control Division
Rationale-Page 3, Permit No. CO0048445
hydraulic capacity of 1.5 MGD or the organic capacity of 3223 lbs BOD5/day, which were specified in
Site Approval 5054. That document should be referred to for any additional information.
Pursuant to Section 100.5.2 of the Water and Wastewater Facility Operator Certification Requirements,
this facility will require a Class B certified operator.
E. Biosolids Treatment and Disposal
Biosolids are treated in to Class A specifications and are, in part, used onsite. Negotiations are ongoing
for further use throughout the Town of Erie.
1. EPA General Permit
EPA Region 8 issued a General Permit (effective October 19, 2007) for Colorado facilities whose
operations generate, treat, and/or use/dispose of sewage sludge by means of land application, landfill,
and surface disposal under the National Pollutant Discharge Elimination System. All Colorado
facilities are required to apply for and to obtain coverage under the EPA General Permit.
2. Biosolids Regulation (Regulation No. 64, Colorado Water Quality Control Commission)
While the EPA is now the issuing agency for biosolids permits, Colorado facilities that land apply
biosolids must comply with requirements of Regulation No. 64, such as the submission of annual
reports as discussed later in this rationale.
V. PERFORMANCE HISTORY
A. Monitoring Data
1. Discharge Monitoring Reports—This is a new facility, thus no monitoring data is available.
VI. TERMS AND CONDITIONS OF PERMIT
A. Discussion of Effluent Limitations
1. Technology Based Limitations
a. Federal Effluent Limitation Guidelines—The Federal Effluent Limitation Guidelines for
domestic wastewater treatment facilities are the secondary treatment standards. These standards
have been adopted into, and arc applied out of, Regulation 62, the Regulations for Effluent
Limitations.
b. Regulation 62: Regulations for Effluent Limitations—These Regulations include effluent
limitations that apply to all discharges of wastewater to State waters. These regulations are
applicable to the discharge from the Town of Erie WWTF.
i. BOD5 and TSS - The BOD5 and TSS concentrations are the most stringent effluent limits and
are therefore applied. The removal percentages for BOD5 and TSS also apply based on the
Regulations for Effluent Limitations.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 4, Permit No. CO0048445
ii. Oil and Grease—The oil and grease limitations from the Regulations for Effluent Limitations
are applied as they are the most stringent limitations.
-The pH limitation specified in the Regulations for Effluent Limitations is not the most
stringent and thus is not used as discussed below.
iv. Total Residual Chlorine - The total residual chlorine concentration specified in the
Regulations for Effluent Limitations is not the most stringent and thus is not used as
discussed below.
2. Water Quality Regulations, Policies, and Guidance Documents
a. Antidegradation - Since the receiving water is Undesignated, an antidegradation review is
required pursuant to Section 31.8 of The Basic Standards and Methodologies for Surface Water.
As set forth in Section VII of the WQA, an antidegradation review was conducted for pollutants
when water quality impacts occurred and when the impacts were significant. Based on the
antidegradation review requirements and the reasonable potential analysis discussed above,
antidegradation-based average concentrations (ADBACs) may be applied.
According to Division procedures, the facility has three options related to antidegradation-based
effluent limits: (1) the facility may accept ADBACs as permit limits (see Section VII of the
WQA); (2) the facility may select permit limits based on their non-impact limit(NIL), which
would result in the facility not being subject to an antidegradation review and thus the
antidegradation-based average concentrations would not apply (the NILs are also contained in
Section VII of the WQA); or(3) the facility may complete an alternatives analysis as set forth in
Section 31.8(3)(d) of the regulations which would result in alternative antidegradation-based
effluent limitations.
The effluent must not cause or contribute to an exceedance of a water quality standard and
therefore the WQBEL must be selected if it is lower than the NIL. Where the WQBEL is not the
most restrictive, the discharger may choose between the NIL or the ADBAC: the NIL results in
no increased water quality impact; the ADBAC results in an"insignificant" increase in water
quality impact. The ADBAC limits are imposed as two-year average limits.
b. Antibacksliding-As the antidegradation evaluation has been completed as outlined under the
Division's Antidegradation Guidance, the antibacksliding requirements in Regulation 61.10 have
been met.
c. Determination of Total Maximum Daily Loads (TMDLs)—This rationale and the accompanying
permit include TMDLs for ammonia developed as specified in the Boulder and St. Vrain TMDL
(2003) and the updated addendum to that document, Report 264 (Lewis and McCutchen,
4/2008), and the corresponding waste load allocations (WLAs) for ammonia. The 2003 TMDL
values for ammonia were developed using the Colorado Ammonia Model (CAM), which has
since been replaced by the AMMTOX model for ammonia. The updated values used in the
WQA are values later derived in Report 264 using AMMTOX. These are the values that will be
applicable to this permit issuance as they were more stringent than the calculated WQBELs. As
required under the Clean Water Act Section 303(d), these TMDLs have been submitted, through
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 5, Permit No. CO0048445
the normal public notification process, to EPA Region VIII for their review and approval. The
receiving stream to which the Town of Erie WWTF discharges is currently listed on the State's
303(d) list for development of TMDLs for E. coli. However, the TMDL has not yet been
finalized. Although this permit establishes limits for E. coli, it does not represent the TMDLs
and waste load allocations, and are therefore are subject to change upon finalization of an
approved TMDL for this segment.
d. Colorado Mixing Zone Regulations—Pursuant to section 31.10 of The Basic Standards and
Methodologies for Surface Water, a mixing zone determination is required for this permitting
action. The Colorado Mixing Zone Implementation Guidance, dated April 2002, identifies the
process for determining the meaningful limit on the area impacted by a discharge to surface water
where standards may be exceeded(i.e., regulatory mixing zone). This guidance document
provides for certain exclusions from further analysis under the regulation,based on site-specific
conditions.
The guidance document provides a mandatory, stepwise decision-making process for
determining if the permit limits will not be affected by this regulation. Exclusion, based on
Extreme Mixing Ratios, may be granted if the ratio of the facility design flow to the chronic low
flow (30E3) is greater than 2:1. Since the ratio of the design flow to the chronic low flow is
.19:1 the permittee must perform additional studies to determine if further requirements apply.
The remaining threshold tests require site-specific information that is currently not available and
thus a determination cannot be made about how the regulation may affect the setting of effluent
limits in this permit. Therefore, a compliance schedule is necessary for acquisition of this
information, which will be used to complete the testing of exclusion thresholds before the next
permit renewal.
g. Reasonable Potential Analysis - Using the assimilative capacities contained in the WQA, an
analysis must be performed to determine whether to include the calculated assimilative capacities
as WQBELs in the permit. This reasonable potential(RP) analysis is based on the Determination
of the Requirement to Include Water Quality Standards-Based Limits in CDPS Permits Based on
Reasonable Potential, dated December, 2002. This guidance document utilizes both quantitative
and qualitative approaches to establish RP depending on the amount of available data.
A qualitative determination of RP may be made where ancillary and/or additional treatment
technologies arc employed to reduce the concentrations of certain pollutants. Because it may be
anticipated that the limits for a parameter could not be met without treatment, and the treatment
is not coincidental to the movement of water through the facility, limits may be included to
assure that treatment is maintained.
For some parameters, recent effluent data or an appropriate number of data points may not be
available, or collected data may be in the wrong form (dissolved vs total) and therefore may not
be available for use in conducting an RP analysis. Thus, consistent with Division procedures,
monitoring will be required to collect samples to support an RP analysis and subsequent
decisions for a numeric limit. A compliance schedule may be added to require the request of a
RP analysis once the appropriate data have been collected.
This is a new facility and therefore there is no data available to conduct a quantitative reasonable
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 6, Permit No. CO0048445
potential analysis. A qualitative assumption for RP has been made for conventional pollutants
that will be discharged from this facility. These include BOD, TSS, pH, oil and grease,E. coli,
and ammonia. Reasonable potential for metals and cyanide is discussed below.
3. Pollutants Limited by Water Quality Standards—The WQA contains the evaluation of pollutants
limited by water quality standards. The mass balance equation shown in Section VI of the WQA was
used for most pollutants to calculate the maximum allowable effluent concentration, M2, that could
be discharged without causing the water quality standard to be violated. For ammonia, the
AMMTOX Model was used to determine the maximum assimilative capacity of the receiving
stream.
The maximum allowable effluent pollutant concentrations determined as part of these calculations
represent the calculated effluent limits that would be protective of water quality. These are also
known as the water quality-based effluent limits (WQBELs). Both acute and chronic WQBELs may
be calculated based on acute and chronic standards, and these may be applied as daily maximum
(acute) or 30-day average (chronic) limits.
pH—This parameter is limited by the water quality standards of 6.5-9.0 s.u., as this range is
more stringent than the range specified under the Regulations for Effluent Limitations. This
limitation is the same as that contained in the previous permit and is imposed upon the effective date
of the permit.
E. Coli—The limitation for E. Coli is based upon the WQBEL as described in the WQA. A
qualitative determination of RP has been made as the treatment facility has been designed to treat
specifically for this parameter and has been built such that this limitation can be met.
Total Residual Chlorine (TRC) - The limitation for TRC is based upon the ADBAC and WQBELs as
described in the WQA, and a qualitative determination of RP has been made as chlorine may be used
in the treatment process. This facility employs UV disinfection and reporting for chlorine will be
required only when it is in use.
Ammonia - The limitation for ammonia is based upon the TMDL as described in the WQA, and
previously in this fact sheet. A qualitative determination of RP has been made as the treatment
facility has been designed to treat specifically for this parameter.
Metals and Cyanide: This is a new facility and there is no influent or effluent data to evaluate for
reasonable potential. The Town's application indicated ninety-three commercial contributors but no
industrial contributors discharging categorical pollutants. This information does not preclude the
possibility that there are contributors to the facility that may have in their discharge, pollutants of
concern to the heath of the receiving stream. Additionally, the size and scope of the facility, coupled
with the populous nature of the area and heavy demands on the vicinity's water resources, leaves the
Division with the belief that there is enough ambiguity surrounding the situation to support a
qualitative finding of reasonable potential for metals. Additionally, this is a new facility for which
the limitations are expected to be met upon the commencement of discharge. Therefore, limits for
metals will be included in the permit.
The facility was issued a PEL in 2006, which was a planning document for the development of
treatment facilities. This document outlines the limitations that were to be met, and therefore were
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 7, Permit No. CO0048445
the limitations that the facility was designed to meet. The standards for the receiving stream have
changed since the PEL was issued but after construction began. These changes in standards now
require antidegradation limitations to be evaluated, which are significantly more stringent than the
limits initially stated in the PEL. Therefore a compliance schedule would be needed to meet these
limits as it is unknown if they can be meet immediately.
Compliance schedules are not normally allowed for new dischargers, but Regulation 61.8(3)(n)(iii)
provides the following: "The first permit issued to a new source or a new discharger shall contain a
schedule of compliance only when necessary to allow a reasonable opportunity to attain compliance
with requirements issued or revised after commencement of construction but less than three years
before commencement of the relevant discharge."
Note that the WQBELs, which have been recalculated in this updated WQA, are in many cases less
stringent than, the limits suggested in the PEL. Where the new WQBELs/ ADBACs for metals are
more stringent than those given in the PEL, compliance schedules have been granted in order to
provide the facility time to meet the new,more stringent limits. A compliance schedule was also
provided for metals that were not included in the PEL such as dissolved iron and total recoverable
uranium, but due to the standards change are now included.
Temperature- The MWAT is the maximum weekly average temperature, as determined by a seven
day rolling average, using at least 3 equally spaced temperature readings in a 24-hour day(at least
every 8 hours for a total of at least 21 data points).
The daily maximum is defined as the maximum 2 hour average, with a minimum of 12 equally
spaced measurements throughout the day. As both of these temperature requirements will likely
require the use of automated temperature measurements and recordings, the permittee is given until
September 1, 2011 to have the proper equipment in place to take the required readings.
Although this is a new facility, new temperature criteria have been adopted and implementation of
the temperature standard has changed between the time that the initial PEL for this facility was
developed, and the time that this permit is being prepared. As it is unknown whether the facility can
meet the new temperature limitation, or whether there is reasonable potential for the facility to cause
or contribute to an exceedance of the water quality standard for temperature, report only conditions
will be required for the duration of this permit. Upon the next permit renewal, the collected
temperature data will be used to determine if there is reasonable potential, and/or if the permittee can
meet the limitation.
Organics— The effluent is not expected or known to contain organic chemicals, and therefore,
limitations for organic chemicals are not needed in this permit.
4. Parameter Speciation
Total/Total Recoverable Metals
For standards based upon the total and total recoverable methods of analysis, the limitations are
based upon the same method as the standard.
Total /Total Recoverable Arsenic
For total recoverable arsenic, the analysis may be performed using a graphite furnace. This method
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 8, Permit No. CO0048445
may produce erroneous results and may not be available to the permittee. Therefore, the total
method of analysis will be specified instead of the total recoverable method.
Total Mercury
Until recently there has not been an effective method for monitoring low-level total mercury
concentrations in either the receiving stream or the facility effluent.
To ensure that adequate data are gathered to determine reasonable potential and consistent with
Division initiatives for mercury, quarterly effluent monitoring for total mercury at low-level
detection methods will be required by the permit.
Dissolved Metals/Potentially Dissolved
For metals with aquatic life-based dissolved standards, effluent limits and monitoring requirements
are typically based upon the potentially dissolved method of analysis, as required under Regulation
31, Basic Standards and Methodologies for Surface Water. Thus, effluent limits and/or monitoring
requirements for these metals will be prescribed as the "potentially dissolved" form.
Dissolved Iron and Dissolved Manganese if WS based
The dissolved iron and chronic manganese standards are drinking water-based standards. Thus,
sample measurements for these two parameters must reflect the dissolved fraction of the metals.
Cyanide:
For cyanide, the acute standard is in the form of"free" cyanide concentrations. However, there is no
analytical procedure for measuring the concentration of free cyanide in a complex effluent.
Therefore, ASTM (American Society for Testing and Materials) analytical procedure D2036-81,
Method C, will be used to measure weak acid dissociable cyanide in the effluent. This analytical
procedure will detect free cyanide plus those forms of complex cyanide that are most readily
converted to free cyanide.
TR Trivalent Chromium
For total recoverable trivalent chromium, the regulations indicate that standard applies to the total of
both the trivalent and hexavalent forms. Therefore, monitoring for total recoverable chromium will
be required.
Hexavalent Chromium
For hexavalent chromium, samples must be unacidified. Accordingly, dissolved concentrations will
be measured rather than potentially dissolved concentrations.
5. Whole Effluent Toxicity(WET) Testing
a. Purpose of WET Testing—The Water Quality Control Division has established the use of WET
testing as a method for identifying and controlling toxic discharges from wastewater treatment
facilities. WET testing is being utilized as a means to ensure that there are no discharges of
pollutants "in amounts, concentrations or combinations which are harmful to the beneficial uses
or toxic to humans, animals, plants, or aquatic life" as required by Section 31.11 (1) of the Basic
Standards and Methodologies for Surface Waters. The requirements for WET testing are being
implemented in accordance with Division policy, Implementation of the Narrative Standard for
Toxicity in Discharge Permits Using Whole Effluent Toxicity(Sept 30, 2010). Note that this
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 9,Permit No. CO0048445
policy has recently been updated and the permittee should refer to this document for additional
information regarding WET.
b. In-Stream Waste Concentration (IWC')—Where monitoring or limitations for WET are deemed
appropriate by the Division, the chronic in-stream dilution is critical in determining whether
acute or chronic conditions shall apply. In accordance with Division policy, for those discharges
where the chronic IWC is greater than 9.1% and the receiving stream has a Class 1 Aquatic Life
use or Class 2 Aquatic Life use with all of the appropriate aquatic life numeric standards, chronic
conditions apply. Where the chronic IWC is less than or equal to 9.1, or the stream is not
classified as described above, acute conditions apply. The chronic IWC is determined using the
following equation:
IWC = [Facility Flow (FF)/(Stream Chronic Low Flow (annual) + FF)] X 100%
The flows and corresponding IWC for the appropriate discharge point are:
Facility Design
Permitted Chronic Low Flow,
Feature 30E3,(cfs) Flow, IWC, CYO
(cfs)
001A 12.2 2.3 16
The IWC for this permit is 16%, which represents a wastewater concentration of 16% effluent to
84%receiving stream.
Chronic WET Monitoring—This is a new major facility discharging to a heavily used and
populated stream segment. This facility discharges ammonia and may discharge metals at
concentrations that could result in chronic toxicity. Additionally, the Division regularly places
WET conditions in permits for major facilities and thus, the permittee will be required to conduct
routine monitoring for chronic toxicity using Ceriodaphnia dubia and Pimephales promelas
(fathead minnows). The results of the testing are to be reported on Division approved forms.
The permittee will be required to conduct two types of statistical evaluations on the data, one
looking for the No Observed Effect Concentration (NOEC) and the second identifying the IC25,
should one exist. Both sets of calculations will look at the full range of toxicity(lethality and
growth or reproduction). If a level of chronic toxicity occurs, such that there is both an NOEC
and an IC25 less than the in-stream waste concentration (IWC), the permittee will be required to
follow the automatic compliance response identified in Part I.A.5. of the permit.
c. General Information—The permittee should read the WET testing section of Part I.A.5. of the
permit carefully, as this information has been updated in accordance with the Division's updated
policy, Implementation of the Narrative Standard for Toxicity in Discharge Permits Using Whole
Effluent Toxicity(Sept 30, 2010) . The permit outlines the test requirements and the required
follow-up actions the permittee must take to resolve a toxicity incident. The permittee should
also read the above mentioned policy which is available on the Permit Section website. The
permittee should be aware that some of the conditions outlined above may be subject to change if
the facility experiences a change in discharge, as outlined in Part II.A.2. of the permit. Such
changes shall be reported to the Division immediately.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 10, Permit No. CO0048445
6. Stormwater: Pursuant to 5 CCR 1002-61.3(2), wastewater treatment facilities with a design flow of
1.0 MGD or more, or that are required to have an approved pretreatment program, are specifically
required to obtain stormwater discharge permit coverage, or a Stormwater No Exposure
Certification, in order to discharge stormwater from their facilities to state waters. The stormwater
discharge permit applicable to wastewater treatment facilities is the CDPS General Permit for
Stormwater Discharges Associated with Light Industrial Activity.
Division records indicate that the Town of Erie applied for and obtained coverage under the CDPS
General Permit for Stormwater Discharges Associated with Light Industrial Activity for the Erie
North Water Reclamation Facility. The CDPS certification number is COR01 1415
7. Economic Reasonableness Evaluation—Section 25-8-503(8) of the revised(June 1985) Colorado
Water Quality Control Act required the Division to "determine whether or not any or all of the water
quality standard based effluent limitations are reasonably related to the economic, environmental,
public health and energy impacts to the public and affected persons, and are in furtherance of the
policies set forth in sections 25-8-102 and 25-8-104."
The Colorado Discharge Permit System Regulations, Regulation No. 61, further define this
requirement under 61.11 and state: "Where economic, environmental, public health and energy
impacts to the public and affected persons have been considered in the classifications and standards
setting process, permits written to meet the standards may be presumed to have taken into
consideration economic factors unless:
a. A new permit is issued where the discharge was not in existence at the time of the classification
and standards rulemaking, or
b. In the case of a continuing discharge, additional information or factors have emerged that were
not anticipated or considered at the time of the classification and standards rulemaking."
The evaluation for this permit shows that this is a new facility not in existence at the time of water
quality standards rulemaking. However,based on available data, the resulting water quality
standard-based effluent limitations are determined to be reasonably related to the economic,
environmental, public health, and energy impacts to the public and affected persons. If the permittee
disagrees with this finding, pursuant to 61.11(b)(ii) of the Colorado Discharge Permit System
Regulations, the permittee should submit all pertinent information to the Division during the public
notice period.
Monitoring
1. Effluent Monitoring—Effluent monitoring will be required as shown in the permit document. Refer
to the permit for locations of monitoring points. Monitoring requirements have been established in
accordance with the frequencies and sample types set forth in the Baseline Monitoring Frequency
Sample Type, and Reduced Monitoring Frequency Policy for Industrial and Domestic Wastewater
Treatment Facilities. This policy includes the methods for reduced monitoring frequencies based
upon facility compliance as well as for considerations given in exchange for instream monitoring
programs initiated by the permittee.
The quarterly monitoring frequency for mercury is imposed consistent with the Divisions' recent
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 11, Permit No. CO0048445
initiative to include quarterly monitoring for mercury because of the changes in analytical procedure
that will allow total mercury to be quantified at much lower concentrations.
2. Pretreatment Program - The permittee is not required to maintain a formal pretreatment program.
However, conditions for industrial waste management conditions will be included in the permit.
Reporting
1. Discharge Monitoring Report—The Town of Erie must submit a Discharge Monitoring Report
(DMR) on a monthly basis to the Division. These reports should contain the required summarization
of the test results for all parameters and monitoring frequencies shown in Part I.B of the permit. See
the permit, Part I.B, C and D for details on such submission.
2. Annual Biosolids Report—The permittee will be required to submit an annual Biosolids Report
which includes the results of all biosolids monitoring performed for the year and information on
management practices, land application sites, site restrictions and certifications. The Annual
Biosolids Report is due by February 19th of the following year. Refer to Part I, Section D.3 of the
permit.
3. Special Reports—Special reports are required in the event of an upset, bypass, or other
noncompliance. Please refer to Part ILA. of the permit for reporting requirements. As above,
submittal of these reports to the US Environmental Protection Agency Region VIII is no longer
required.
D. Additional Terms and Conditions
1. Signatory Requirements— Signatory requirements for reports and submittals are discussed in Part I,
Section D.1 of the permit.
2. Compliance Schedules—The following compliance schedules are included in the permit. See Part
I.B of the permit for more information.
Installation of Temperature Monitoring Equipment: The permittee is to submit a document
certifying that continuous temperature and flow monitoring equipment has been installed and is
operational by August 31, 2011
Mixing Zone Analysis: Collect site-specific data, perform threshold tests based on Mixing Zone
Exclusion Tables, and submit study results. Completion by March 30, 2013.
Activities to Meet Final Metals Limits: The permitte is to identify sources of metals to the facility,
submit progress reports that describe the steps being taken to comply with final limits and complete
activities or construction that will allow compliance. Completion by January 1, 2015.
All information and written reports required by the following compliance schedules should be
directed to the Permits Section for final review unless otherwise stated.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 12, Permit No. CO0048445
VII. REFERENCES
A. Colorado Department of Public Health and Environment, Water Quality Control Division Files, for
Permit Number CO0048445.
B. "Design Criteria Considered in the Review of Wastewater Treatment Facilities", Policy 96-1, Colorado
Department of Public Health and Environment, Water Quality Control Commission, April 2007.
C. Basic Standards and Methodologies for Surface Water, Regulation No. 31, Colorado Department of
Public Health and Environment, Water Quality Control Commission, effective November 30, 2009.
D. Classifications and Numeric Standards for South Platte River Basin, Laramie River Basin, Republican
River Basin, Smoky Hill River Basin, Regulation No. 38, Colorado Department of Public Health and
Environment, Water Quality Control Commission, effective June 30, 2010.
E. Colorado Discharge Permit System Regulations, Regulation No. 61, Colorado Department of Public
Health and Environment, Water Quality Control Commission, effective August 30, 2010
F. Regulations for Effluent Limitations, Regulation No. 62, Colorado Department of Public Health and
Environment, Water Quality Control Commission, effective March 30, 2008.
G. Pretreatment Regulations, Regulation No. 63, Colorado Department of Public Health and Environment,
Water Quality Control Commission, effective April 01, 2007.
H. Biosolids Regulation, Regulation No. 64, Colorado Department of Public Health and Environment,
Water Quality Control Commission, effective March 30, 2010.
I. Colorado's Section 303(d) List of Impaired Waters and Monitoring and Evaluation List, Regulation No
993Colorado Department of Public Health and Environment, Water Quality Control Commission,
effective April 30, 2010.
J. Antidegradation Significance Determination for New or Increased Water Quality Impacts, Procedural
Guidance, Colorado Department of Public Health and Environment, Water Quality Control Division,
effective December 2001.
K. Memorandum Re: First Update to (Antidegradation) Guidance Version 1.0, Colorado Department of
Public Health and Environment, Water Quality Control Division, effective April 23, 2002.
L. Determination of the Requirement to Include Water Quality Standards-Based Limits in CDPS Permits
Based on Reasonable Potential, Colorado Department of Public Health and Environment, Water Quality
Control Division, effective December2002.
M. The Colorado Mixing Zone Implementation Guidance, Colorado Department of Public Health and
Environment, Water Quality Control Division, effective April 2002.
N. Baseline Monitoring Frequency, Sample Type, and Reduced Monitoring Frequency Policy for Domestic
and Industrial Wastewater Treatment Facilities, Water Quality Control Division Policy WQP-20, May 1,
2007.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale-Page 13, Permit No. C00048445
O. Policy for Conducting Assessments for Implementation of Temperature Standards in Discharge Permits,
Colorado Department of Public Health and Environment, Water Quality Control Division, Policy
Number WQP-23, effective July 3, 2008.
P. Procedural Regulations for Site Applications for Domestic Wastewater Treatment Works, Regulation
No. 22, Colorado Department of Public Health and Environment, Water Quality Control Commission,
effective September 30, 2009.
Q. Regulation Controlling discharges to Storm Sewers, Regulation No. 65, Colorado Department of Public
Health and Environment, Water Quality Control Commission, effective May 30, 2008.
R. Water and Wastewater Facility Operator Certification Requirements, Regulation No. 100, Colorado
Department of Public Health and Environment, Water Quality Control Commission, effective September
30, 2007.
John Nieland
October 18, 2010
VIII. PUBLIC NOTICE COMMENTS
AUTHORIZATION TO DISCHARGE UNDER THE
COLORADO DISCHARGE PERMIT SYSTEM
In compliance with the provisions of the Colorado Water Quality Control Act, (25-8-101 et seq., CRS, 1973 as amended),
for both discharges to surface and ground waters, and the Federal Water Pollution Control Act, as amended(33 U.S.C.
1251 et seq.; the "Act"), for discharges to surface waters only,the
Town of Erie
is authorized to discharge from the North Water Reclamation Facility wastewater treatment plant located at North 1/4,
Section 31, T2N,R68W; Lat: 40.0979 N, Long: 105.0432 W
to Boulder Creek
in accordance with effluent limitations,monitoring requirements and other conditions set forth in Parts I and II hereof. All
discharges authorized herein shall be consistent with the terms and conditions of this permit.
The applicant may demand an adjudicatory hearing within thirty(30) days of the date of issuance of the final permit
determination,per the Colorado State Discharge Permit System Regulation 61.7(1). Should the applicant choose to contest
any of the effluent limitations,monitoring requirements or other conditions contained herein,the applicant must comply
with Section 24-4-104 CRS 1973 and the Colorado State Discharge Permit System Regulations. Failure to contest any
such effluent limitation, monitoring requirement, or other condition, constitutes consent to the condition by the applicant.
This permit and the authorization to discharge shall expire at midnight,
Issued and Signed this day of
COLORADO DEPARTMENT OF PUBLIC HEALTH AND
ENVIRONMENT
Public Notice
Version of Permit Janet Kieler,Permits Section Manager
Water Quality Control Division
Permit,Part I
Page 2 of 34
Permit No. CO0048445
TABLE OF CONTENTS
PARTI 3
A. EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS 3
I. Permitted Features(s) 3
2. Limitations,Monitoring Frequencies and Sample Types for Effluent Parameters 3
3. Monitoring Frequency and Sample Type Influent Parameters 6
B. TERMS AND CONDITIONS 6
I. Service Area 6
2. Design Capacity 6
3. Expansion Requirements 6
4. Facilities Operation and Maintenance 7
5. Chronic WET Testing—Outfall 001k 7
6. Compliance Schedule(s) 10
7. Industrial Waste Management 11
C. DEFINITION OF TERMS 13
D. General Monitoring,SAmpling and reporting requirements 18
1. Routine Reporting of Data 18
2. Annual Biosolids Report 18
3. Representative Sampling 18
4. Influent and Effluent Sampling Points 19
5. Analytical and Sampling Methods for Monitoring 19
6. Records 20
7. Flow Measuring Devices 20
8. Signatory Requirements 21
PART II 22
A. NOTIFICATION REQUIREMENTS 22
1. Notification to Parties 22
2. Change in Discharge 22
3. Special Notifications-Definitions 22
4. Noncompliance Notification 23
5. Other Notification Requirements 23
6. Bypass Notification 24
7. Upsets 24
8. Discharge Point 25
9. Proper Operation and Maintenance 25
10. Minimization of Adverse Impact 25
I I. Removed Substances 25
12. Submission of Incorrect or Incomplete Information 25
13. Bypass 25
14. Reduction,Loss,or Failure of Treatment Facility 26
B. RESPONSIBILITIES 26
I. Inspections and Right to Entry 26
2. Duty to Provide Information 26
3. Transfer of Ownership or Control 26
4. Availability of Reports 27
5. Modification,Suspension,Revocation,or Termination of Permits By the Division 27
6. Oil and Hazardous Substance Liability 29
7. State Laws 29
8. Permit Violations 29
9. Property Rights 30
10. Severability 30
11. Renewal Application 30
12. Confidentiality 30
13. Fees 30
14. Duration of Permit 30
15. Section 307 Toxics 30
16. Effect of Permit Issuance 30
PART III 32
Permit,Part I
Page 3 of 34
Permit No. CO0048445
PARTI
A. EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
1. Permitted Features(s)
Beginning no later than the effective date of this permit and lasting through the expiration date,the permittee is authorized to
discharge from,and self monitoring samples taken in accordance with the monitoring requirements shall be obtained from
permitted feature(s):
001A following disinfection and prior to mixing with the receiving stream.40.0979 N, 105.0432 W
The location(s)provided above will serve as the point(s)of compliance for this permit and are appropriate as they are located
after all treatment and prior to discharge to the receiving water.
In accordance with the Water Quality Control Commission Regulations for Effluent Limitations, Section 62.4,and the
Colorado Discharge Permit System Regulations, Section 61.8(2),5 C.C.R. 1002-61,the permitted discharge shall not contain
effluent parameter concentrations which exceed the following limitations specified below or exceed the specified flow
limitation.
2. Limitations,Monitoring Frequencies and Sample Types for Effluent Parameters
In order to obtain an indication of the probable compliance or noncompliance with the effluent limitations specified in Part
I.A,the permittee shall monitor all effluent parameters at the frequencies and sample types specified below. Such monitoring
will begin immediately and last for the life of the permit unless otherwise noted. The results of such monitoring shall be
reported on the Discharge Monitoring Report form(See Part I.D.)
Self-monitoring sampling by the permittee for compliance with the monitoring requirements specified above shall be
performed at the location(s)noted in Part I.A.1 above.
If the permittee,using an approved analytical method,monitors any parameter more frequently than required by this permit,
then the results of such monitoring shall be included in the calculation and reporting of the values required in the Discharge
Monitoring Report Form(DMRs)or other forms as required by the Division. Such increased frequency shall also be
indicated.
Percentage Removal Requirements(BOD,and TSS and TSS Limitations) -If noted in the limits table(s),the arithmetic mean
of the BOD5 and TSS concentrations for effluent samples collected during the calendar month shall demonstrate a minimum
of eighty-five percent(85%)removal of both BOD5 and TSS,as measured by dividing the respective difference between the
mean influent and effluent concentrations for the calendar month by the respective mean influent concentration for the
calendar month, and multiplying the quotient by 100.
Oil and Grease Monitoring: For every outfall with oil and grease monitoring, in the event an oil sheen or floating oil is
observed,a grab sample shall be collected and analyzed for oil and grease,and reported on the appropriate DMR under
parameter 03582. In addition,corrective action shall be taken immediately to mitigate the discharge of oil and grease. A
description of the corrective action taken should be included with the DMR.
Total Residual Chlorine: Monitoring for TRC is required only when chlorine is in use.
Metals:Metals concentrations measured in compliance with the effluent monitoring requirements listed in Part I.A of this
permit may be used to satisfy any pretreatment or industrial waste management metals monitoring requirements listed in Part
I.B.8,if the metals are in the same form(i.e. total). The special sampling procedures(e.g. 24-hour composite samples)
specified in Part I.B.8 must be followed.
Permit,Part 1
Page 4 of 34
Permit No.CO0048445
Permitted Feature 001 A
Effluent Limitations Maximum Concentrations MonitorinL Requirements
ICIS Effluent Parameter
Code 330_Day, 7-Day Daily 2-fir
RoHim/ Frequency
Averaae Averaue Maximum
Average
50050 Effluent Flow(MGD) 1.5 Report Continuous
00010 Temp(°C) beginning NA Report ' Report Continuous
9/1/11
00400 pH(su) 16.5-9 Daily
31633 E.coli(#/100 ml) 126 252 2 Days/Week
50060 TRC(mg/1) 0.068 0.072 5 Days/Week
00610 NH3 as N,Tot(mg/I)Jan 4.8 4.8 2 Days/Week
00610 NH3 as N,Tot(mg/1)Feb 2.8 2.8 2 Days/Week
00610 NH3 as N,Tot(mg/1)Mar 3.1 3.3 2 Days/Week
00610 NH3 as N,Tot(mg/1)Apr 2.7 2.9 2 Days/Week
00610 NH3 as N,Tot(mg/1)May 2.3 2.3 2 Days/Week
00610 NH3 as N,Tot(mg/1)Jun 2.4 3.8 2 Days/Week
00610 NH3 as N,Tot(mg/1)Jul 2 2 2 Days/Week
00610 NH3 as N,Tot(mg/1)Aug 1.9 1.9 2 Days/Week
00610 NH3 as N,Tot(mg/1)Sep 2.1 2.1 2 Days/Week
00610 NH3 as N,Tot(mg/I)Oct _3.2 4.4 2 Days/Week
00610 NH3 as N,Tot(mg/1)Nov 4.8 9 2 Days/Week
00610 NH3 as N,Tot(mg/I)Dec 5 7.8 2 Days/Week
00310 BOD5,effluent(mg/1) 30 45 2 Days/Week
81010 BOD5 (%removal) 85(min) 2 Days/Week
00530 TSS,effluent(mg/1) 30 45 2 Days/Week
81011 TSS(%removal) 85(min) 2 Days/Week
03582 Oil and Grease(mg/1) NA 10 Daily
00978 As,TR(µg/1),through Report Report Monthly
12/31/2014
00978 As,TR(ug/l),beginning 0.12 NA Monthly
1/1/2015
01000 As,PD(ug/l) NA 1276 Monthly
01025 Cd,PD(µg/I),through 1.9 18 Report Monthly
12/31/2014
01025 Cd,PD(ug/I),beginning 1.9 18 0.1 l Monthly
1/1/2015 .
01030 Cr+3,PD(µg/I)through NA 1215 Monthly
12/31/2014
01034 Cr,TR(ug/1),through NA Report Report Monthly
12/31/2014
01034 Cr,TR(ug/l),beginning NA 189 28 Monthly
1/1/2015
01032 Cr+6,Dis(ug/1) 68 61 11 Monthly
01040 Cu,PD(µg/1),through 75 82 Report Monthly
Permit, Part I
Page 5 of 34
Permit No.CO0048445
12/31/2014
01040 Cu,PD(µg/1),beginning 75 82 4.9 Monthly
1/1/2015
00718 CN,WAD(µg/I)through NA 19 Report Monthly
12/31/2014
00718 CN,WAD(µg/l)beginning NA 19 2.8 Monthly
1/1/2015
01046 Fe,Dis(µg/1)through Report NA Report Monthly
12/31/2014
01046 Fe,Dis(µg/1)beginning 1302 NA 102 Monthly
1/1/2015
00980 Fe,TR(µg/I) 3713 NA 1 151 Monthly
01049 Pb,PD(µg 1))through 27 526 Report Monthly
12/31/2014
01049 Pb,PD(ug/1)beginning 27 526 0.81 Monthly
1/1/2015
01056 Mn,PD(µg/1) 2302 14207 Monthly
01056 Mn,Dis(µg/1))through Report Report Monthly
12/31/2014
01056 Mn,Dis(µg/1)beginning 55 18 Monthly
1/1/2015 ,
71900 Hg,Tot(µg/1)through 0.062 NA Report Monthly
12/31/2014
71900 Hg,Tot(µg/I)beginning 0.062 NA 0.0093 Monthly
1/1/2015
01065 Ni,PD(µg/I)through 591 3249 Report Monthly
12/31/2014
01065 Ni,PD(µg/I)beginning 591 3249 87 Monthly
1/1/2015
01145 Se,PD(µg/I)through 4.6 56 Report Monthly
12/31/2014
01145 Se,PD(µg/1)beginning 4.6 56 2.4 Monthly
1/1/2015
01075 Ag,PD(µg/1)through 6.1 26 Report Monthly
12/31/2014
01075 Ag,PD(µg/1))beginning 6.1 26 0.51 Monthly
1/1/2015
22708 U,TR(ug/1)through NA Report Report Monthly
12/31/2014
22708 U,TR(ug/l)beginning NA 113 33 Monthly
1/1/2015
01090 Zn, PD(µg/1)through NA 915 Report Monthly
12/31/2014
01090 Zn,PD(ug/l)beginning NA 915 192 Monthly
1/1/2015
WET,chronic
Static Renewal 7 Day
TKP6C Chronic Pimephales NOEC or Quarterly
promelas IC25>IWC
Static Renewal 7 Day NOEC or
TKP3B Chronic Ceriodaphnia IC25>IWC Quarterly
dubia
Permit, Part I
Page 6 of 34
Permit No. CO0048445
3. Monitoring Frequency and Sample Type Influent Parameters
Regardless of whether or not an effluent discharge occurs and in order to obtain an indication of the current influent loading
as compared to the approved capacity specified in Part 1,Section A.2.;the permittee shall monitor influent parameters at the
following required frequencies,the results to be reported on the Discharge Monitoring Report(See Part I.D):
If the permittee monitors any parameter more frequently than required by the permit,using an approved test procedure or as
specified in the permit,the result of this monitoring shall be included in the calculation and reporting of data to the Division.
Self-monitoring samples taken in compliance with the monitoring requirements specified above shall be taken at the following
location(s): Outfall 3001,at a representative point prior to biological treatment..
Permitted Feature 3001
ICIS Influent Parameter Frequency Sample Type
Code
50050 G Flow,MGD Continuous Recorder
00180 G Plant Capacity(%of Capacity- Monthly Calculated
Hydraulic) *
00310 O BOD5,mg/1 2 times per week Composite
00310 G BOD5,lbs/day 2 times per week Calculated
00180 O Plant Capacity(%of Capacity- Monthly Calculated
Organic) *
00530 G Total Suspended Solids,TSS,mg/1 2 times per week Composite
*The%capacity is to be reported against the listed capacities of 1.5 MGD for the hydraulic capacity and 3,223 lbs/day for
the organic capacities as noted in Site Approval 5054. The percentage should be calculated using the 30-day average values
divided by the corresponding capacity,times 100.
B. TERMS AND CONDITIONS
1. Service Area
All wastewater flows contributed in the service area may be accepted by the Town of Erie for treatment at the permittee's
wastewater treatment plant provided that such acceptance does not cause or contribute to an exceedance of the throughput or
design capacity of the treatment works or the effluent limitations in Part I.A,or constitute a substantial impact to the
functioning of the treatment works,degrade the quality of the receiving waters,or harm human health,or the environment.
In addition,the permittee shall enter into and maintain service agreements with any municipalities that discharge into the
wastewater treatment facility. The service agreements shall contain all provisions necessary to protect the financial,physical,
and operational integrity of the wastewater treatment works.
2. Design Capacity
Based on Site Approval 5054,the design capacity of this domestic wastewater treatment works is 1.5 million gallons per day
(MGD)for hydraulic flow(30-day average)and 3223 lbs.BOD5 per day for organic loading(30-day average).
3. Expansion Requirements
Pursuant to Colorado Law,C.R.S. 25-8-501 (5 d&e),the permittee is required to initiate engineering and financial planning
for expansion of the domestic wastewater treatment works whenever throughput reaches eighty(80)percent of the treatment
Permit,Part I
Page 7 of 34
Permit No. CO0048445
capacity. Such planning may be deemed unnecessary upon a showing that the area served by the domestic wastewater
treatment works has a stable or declining population;but this provision shall not be construed as preventing periodic review
by the Division should it be felt that growth is occurring or will occur in the area.
The permittee shall commence construction of such domestic wastewater treatment works expansion whenever throughput
reaches ninety-five(95)percent of the treatment capacity or,in the case of a municipality,either commence construction or
cease issuance of building permits within such municipality until such construction is commenced; except that building
permits may continue to be issued for any construction which would not have the effect of increasing the input of wastewater
to the sewage treatment works of the municipality involved.
Where unusual circumstances result in throughput exceeding 80%of treatment capacity,the permittee may,in lieu of
initiating planning for expansion, submit a report to the Division that demonstrates that it is unlikely that the event will
reoccur,or even if it were to reoccur,that 95%of the treatment capacity would not be exceeded.
Where unusual circumstances result in throughput exceeding 95%of the treatment capacity,the permittee may,in lieu of
initiating construction of the expansion,submit a report to the Division that demonstrates that the domestic wastewater
treatment works was in compliance at all times during the events and that it is extremely unlikely that the event will reoccur.
Where the permittee submits a report pursuant to unusual circumstances,and the Division,upon review of such report,
determines in writing to the permittee that the report does not support the required findings, the permittee shall initiate
planning and/or construction of the domestic wastewater treatment works as appropriate.
4. Facilities Operation and Maintenance
The permittee shall at all times properly operate and maintain all facilities and systems of treatment and control including all
portions of the collection system and lift stations owned by the permittee(and related appurtenances)which are installed or
used by the permittee as necessary to achieve compliance with the conditions of this permit. Proper operation and
maintenance also includes adequate laboratory controls and appropriate quality assurance procedures. This provision requires
the operation of back-up or auxiliary facilities or similar systems when installed by the permittee only when necessary to
achieve compliance with the conditions of the permit. However,the permittee shall operate,at a minimum,one complete set
of each main line unit treatment process whether or not this process is needed to achieve permit effluent compliance. Any
sludge produced at the wastewater treatment facility shall be disposed of in accordance with State and Federal guidelines and
regulations.
5. Chronic WET Testing—Outfall 001A:
a. General Testing and Reporting Requirements
The permittee shall conduct the chronic WET test using Ceriodaphnia dubia and Pimephales promelas,as a static
renewal 7-day test using three separate composite samples. The permittee shall conduct each chronic WET test in
accordance with the 40 CFR Part 136 methods described in Short-term Methods for Estimating the Chronic Toxicity
of Effluents and Receiving Water to Freshwater Organisms,Fourth Edition,October 2002(EPA-821-R-02-013)or
the most current edition.
The following minimum dilution series should be used:0%effluent(control),4%,8%, 16%, 58%,and 100%effluent.
If the permittee uses more dilutions than prescribed,and accelerated testing is to be performed,the same dilution
series shall be used in the accelerated testing(if applicable)as was initially used in the failed test.
Tests shall be done at the frequency listed in Part I.A.I. Test results shall be reported along with the Discharge
Monitoring Report(DMR)submitted for the end of the reporting period when the sample was taken.(i.e.,WET
testing results for the calendar quarter ending March 31 shall be reported with the DMR due April 28,etc.) The
permittee shall submit all laboratory statistical summary sheets,summaries of the determination of a valid,invalid or
inconclusive test,and copies of the chain of custody forms,along with the DMR for the reporting period.
If a test is considered invalid,the permittee is required to perform additional testing during the monitoring period to
obtain a valid test result. Failure to obtain a valid test result during the monitoring period shall result in a violation of
the permit for failure to monitor.
Permit,Part I
Page 8 of 34
Permit No. CO0048445
b. Violations of the Permit Limit,Failure of One Test Statistical Endpoint and Division Notification
A chronic WET test is considered a violation of a permit limitation when both the NOEC and the IC25 are at any
effluent concentration less than the IWC. The IWC for this permit has been determined to be 16%effluent.
A chronic WET test is considered to have failed one of the two statistical endpoints when either the NOEC or the IC25
are at any effluent concentration less than the IWC. The IWC for this permit has been determined to be 16%effluent.
In the event of a permit violation,or when two consecutive reporting periods have resulted in failure of one of the two
statistical endpoints(regardless of which statistical endpoints are failed),the permittee must provide written
notification to the Division. Such notification should explain whether it was a violation or two consecutive failures of
a single endpoint,and must indicate whether accelerated testing or a Toxicity Identification Evaluation or Toxicity
Reduction Evaluation(TIE or TRE)is being performed,unless otherwise exempted, in writing,by the Division.
Notification must be received by the Division within 14 calendar days of the permittee receiving notice of the
WET testing results.
c. Automatic Compliance Response
The permittee is responsible for implementing the automatic compliance response provisions of this permit when one
of the following occurs:
• there is a violation of the permit limit(both the NOEC and the IC25 endpoints are less than the applicable
IWC)
• two consecutive monitoring periods have resulted in failure of one of the two statistical endpoints(either the
IC25 or the NOEC)
• the permittee is otherwise informed by the Division that a compliance response is necessary
When one of the above listed events occurs,the following automatic compliance response shall apply. The permittee
shall either:
• conduct accelerated testing using the single species found to be more sensitive
• conduct a Toxicity Identification Evaluation/Toxicity Reduction Evaluation(TIE/TRE)investigation as
described in Part I.A.3.b.
i. Accelerated Testing
If accelerated testing is being performed,testing will be at least once every two weeks for up to five tests,usine
only the IC25 statistical endpoint to determine if the test passed or failed at the appropriate IWC. Accelerated
testing shall continue until; 1)two consecutive tests fail or three of five tests fail,in which case a pattern of
toxicity has been demonstrated or 2)two consecutive tests pass or three of five tests pass,in which case no
pattern of toxicity has been found. Note that the same dilution series should be used in the accelerated testing as
was used in the initial test(s)that result in the accelerated testing requirement.
If accelerated testing is required due to failure of one statistical endpoint in two consecutive monitoring periods,
and in both of those failures it was the NOEC endpoint that was failed,then the NOEC shall be the only statistical
endpoint used to determined whether the accelerated testing passed or failed at the appropriate IWC. Note that
the same dilution series should be used in the accelerated testing as was used in the initial test(s)that result in the
accelerated testing requirement.
If no pattern of toxicity is found the toxicity episode is considered to be ended and routine testing is to resume. If
a pattern of toxicity is found,a TIE/TRE investigation is to be performed. If a pattern of toxicity is not
demonstrated but a significant level of erratic toxicity is found,the Division may require an increased frequency
of routine monitoring or some other modified approach. The permittee shall provide written notification of the
results within 14 calendar days of completion of the Pattern of Toxicity/No Toxicity demonstration.
Permit,Part
Page 9 of 34
Permit No. CO0048445
ii. Toxicity Identification Evaluation/Toxicity Reduction Evaluation(TIE/TRE)
If a TIE/TRE is being performed,the results of the investigation are to be received by the Division within 180
days of the demonstration chronic WET in the routine test,as defined above, or if accelerated testing was
performed,the date the pattern of toxicity is demonstrated. A status report is to be provided to the Division at the
60 and 120 day points of the TIE/TRE investigation. The Division may extend the time frame for investigation
where reasonable justification exists. A request for an extension must be made in writing and received prior to
the 180 day deadline. Such request must include a justification and supporting data for such an extension.
Under a TIE,the permittee may use the time for investigation to conduct a preliminary TIE(PTIE)or move
directly into the TIE. A PTIE consists of a brief search for possible sources of WET,where a specific
parameter(s)is reasonably suspected to have caused such toxicity,and could be identified more simply and cost
effectively than a formal TIE. If the PTIE allows resolution of the WET incident,the TIE need not necessarily be
conducted in its entirety. If,however,WET is not identified or resolved during the PTIE,the TIE must be
conducted within the allowed 180 day time frame.
The Division recommends that the EPA guidance documents regarding TIEs be followed. If another method is to
be used,this procedure should be submitted to the Division prior to initiating the TIE.
If the pollutant(s)causing toxicity is/are identified,and is/are controlled by a permit effluent limitation(s),this
permit may be modified upon request to adjust permit requirements regarding the automatic compliance response.
If the pollutant(s)causing toxicity is/are identified,and is/are not controlled by a permit effluent limitation(s),the
Division may develop limitations the parameter(s),and the permit may be reopened to include these limitations.
If the pollutant causing toxicity is not able to be identified,or is unable to be specifically identified,or is not able
to be controlled by an effluent limit,the permittee will be required to perform either item 1 or item 2 below.
I) Conduct an investigation which demonstrates actual instream aquatic life conditions upstream and
downstream of the discharge,or identify,for Division approval,and conduct an alternative investigation
which demonstrates the actual instream impact. This should include WET testing and chemical analyses of
the ambient water. Depending on the results of the study,the permittee may also be required to identify the
control program necessary to eliminate the toxicity and its cost. Data collected maybe presented to the
WQCC for consideration at the next appropriate triennial review of the stream standards;
2) Move to a TRE by identifying the necessary control program or activity and proceed with elimination of
the toxicity so as to meet the WET effluent limit.
If toxicity spontaneously disappears in the midst of a TIE,the permittee shall notify the Division within 10 days
of such disappearance. The Division may require the permittee to conduct accelerated testing to demonstrate that
no pattern of toxicity exists,or may amend the permit to require an increased frequency of WET testing for some
period of time. If no pattern of toxicity is demonstrated through the accelerated testing or the increased
monitoring frequency,the toxicity incident response will be closed and normal WET testing shall resume.
The control program developed during a TRE consists of the measures determined to be the most feasible to
eliminate WET. This may happen through the identification of the toxicant(s)and then a control program aimed
specifically at that toxicant(s)or through the identification of more general toxicant treatability processes. A
control program is to be developed and submitted to the Division within 180 days of beginning a TRE. Status
reports on the TRE are to be provided to the Division at the 60 and 120 day points of the TRE investigation.
If toxicity spontaneously disappears in the midst of a TRE, the permittce shall notify the Division within 10 days
of such disappearance. The Division may require the permittee to conduct accelerated testing to demonstrate that
no pattern of toxicity exists,or may amend the permit to require an increased frequency for some period of time.
If no pattern of toxicity is demonstrated through the accelerated testing or the increased monitoring frequency,the
toxicity incident response will be closed and normal WET testing shall resume.
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Permit No. CO0048445
d. Toxicity Reopener
This permit may be reopened and modified to include additional or modified numerical permit limitations,new or
modified compliance response requirements,changes in the WET testing protocol,the addition of both acute and chronic
WET requirements,or any other conditions related to the control of toxicants.
6. Compliance Schedule(s)
All information and written reports required by the following compliance schedules should be directed to the Permits Unit for
final review unless otherwise stated.
a. Installation of Temperature Monitoring Equipment- The following compliance schedule is included to give the facility
time to install temperature monitoring equipment for the effluent.
Code Event Description Due Date
04301 Install The permittee is to submit a document certifying that continuous
Temperature temperature and flow monitoring equipment has been installed and is 8/31/2011
Meters operational.
b. Mixing Zone Analyses—Conduct remaining threshold tests for exclusion from further analysis under Mixing Zone
Regulations. The second threshold test is the Application of the Mixing Zone Exclusion Tables(p. 20, Colorado Mixing
Zone Implementation Guidance,February 2002). Under this compliance action,the permittee will collect the necessary site-
specific data,perform the required analysis,and provide a report to the Division. The report will indicate the findings of this
threshold test and,if not excluded,provide the workplan for the next threshold test(i.e.,determining of the size of the
physical and regulatory mixing zones).
Code Event Description Due Date
50008 Submit Study Collect site-specific data,perform threshold tests based on Mixing 3/30/2012
Results Zone Exclusion Tables,and submit study results.
50008 Submit Study If a low flow condition is not reached on the receiving water 3/30/2013
Results during the first year,the permittee shall collect the site-specific
data,perform threshold tests based on Mixing Zone Exclusion
Tables,and submit study results.
c. Activities to Meet Final Limits for Metals—In order to meet metals limitations,the following schedule will be
included in the permit.
Code Event Description Due Date
43699 Facility Submit a report that identifies sources of metals to the wastewater 12/31/11
Evaluation Plan treatment facility and identifies strategies to control these sources
or treatment alternatives such that compliance with the final
limitations may be attained.
00899 Implementation Submit a progress report summarizing the progress in 12/31/12
Schedule implementing the strategies to control sources such that
compliance with the final metals limitations may be attained.
00899 Implementation Submit a progress report summarizing the progress in 12/31/13
Schedule implementing the strategies to control sources such that
compliance with the final metals limitations maybe attained.
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Permit No. CO0048445
CS017 Achieve Final Submit study results that show compliance has been attained with 12/31/14
Compliance with the final metal s limitations.
Emissions or
Discharge
Limits
No later than 14 calendar days following each date identified in the above schedules of compliance,the permittee shall submit
either a report of progress or, in the case of specific actions being required by identified dates,a written notice of compliance
or noncompliance,any remedial actions taken,and the probability of meeting the next scheduled requirement.
7. Industrial Waste Management
a. The Permittee has the responsibility to protect the Domestic Wastewater Treatment Works(DWTW),as defined at
section 25.8.103(5)of the Colorado Water Quality Control Act,or the Publicly-Owned Treatment Works(POTW),as
defined at 40 CFR section 403.3(q)of the federal pretreatment regulations,from pollutants which would cause pass
through or interference,as defined at 40 CFR 403.3(p)and(k),or otherwise be incompatible with operation of the
treatment works including interference with the use or disposal of municipal sludge.
b. Pretreatment Standards(40 CFR Section 403.5)developed pursuant to Section 307 of the Federal Clean Water Act(the
Act)require that the Permittee shall not allow,under any circumstances,the introduction of the following pollutants to
the DWTW from any source of non-domestic discharge:
i. Pollutants which create a fire or explosion hazard in the DWTW,including,but not limited to,wastestreams with a
closed cup flashpoint of less than sixty(60)degrees Centigrade(140 degrees Fahrenheit)using the test methods
specified in 40 CFR Section 261.21;
ii. Pollutants which will cause corrosive structural damage to the DWTW,but in no case discharges with a pH of lower
than 5.0 s.u.,unless the treatment facilities are specifically designed to accommodate such discharges;
iii. Solid or viscous pollutants in amounts which will cause obstruction to the flow in the DWTW,or otherwise interfere
with the operation of the DWTW;
iv. Any pollutant, including oxygen demanding pollutants(e.g.,BOD),released in a discharge at a flow rate and/or
pollutant concentration which will cause Interference with any treatment process at the DWTW;
v. Heat in amounts which will inhibit biological activity in the DWTW resulting in Interference,but in no case heat in
such quantities that the temperature at the DWTW treatment plant exceeds forty(40)degrees Centigrade(104
degrees Fahrenheit)unless the Approval Authority,upon request of the DWTW,approves alternate temperature
limits;
vi. Petroleum oil,non-biodegradable cutting oil,or products of mineral oil origin in amounts that will cause Interference
or Pass Through;
vii. Pollutants which result in the presence of toxic gases,vapors,or fumes within the DWTW in a quantity that may
cause acute worker health and safety problems;
viii.Any trucked or hauled pollutants,except at discharge points designated by the DWTW;and
ix. Any specific pollutant that exceeds a local limitation established by the Permittee in accordance with the
requirements of 40 CFR Section 403.5(c)and(d).
x. Any other pollutant which may cause Pass Through or Interference.
c. EPA shall be the Approval Authority and the mailing address for all reporting and notifications to the Approval Authority
shall be:USEPA 1595 Wynkoop St. SENF-W-NP,Denver,CO 80202-1129. Should the State be delegated authority to
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Permit No. CO0048445
implement and enforce the Pretreatment Program in the future,the Permittee shall be notified of the delegation and the
state permitting authority shall become the Approval Authority.
d. In addition to the general limitations expressed above,more specific Pretreatment Standards have been and will be
promulgated for specific industrial categories under Section 307 of the Act(40 CFR Part 405 et. seq.).
e. The Permittee must notify the state permitting authority and the Approval Authority,of any new introductions by new or
existing industrial users or any substantial change in pollutants from any industrial user within sixty(60)days following
the introduction or change. Such notice must identify:
i. Any new introduction of pollutants into the DWTW from an industrial user which would be subject to Sections 301,
306,or 307 of the Act if it were directly discharging those pollutants;or
ii. Any substantial change in the volume or character of pollutants being introduced into the DWTW by any industrial
user;
iii. For the purposes of this section,adequate notice shall include information on:
(A) The identity of the industrial user;
(B) The nature and concentration of pollutants in the discharge and the average and maximum flow of the
discharge to be introduced into the DWTW;and
(C) Any anticipated impact of the change on the quantity or quality of effluent to be discharged from or
biosolids or sludge produced at such DWTW.
iv. For the purposes of this section,an industrial user shall include:
(A) Any discharger subject to Categorical Pretreatment Standards under Section 307 of the Act and 40 CFR
chapter 1 and subchapter N;
(B) Any discharger which has a process wastewater flow of 25,000 gallons or more per day;
(C) Any discharger contributing five percent or more of the average dry weather hydraulic or organic
capacity of the DWTW treatment plant;
(D) Any discharger who is designated by the Approval Authority as having a reasonable potential for
adversely affecting the DWTWs operation or for violating any Pretreatment Standard or requirements;
f At such time as a specific Pretreatment Standard or requirement becomes applicable to an industrial user of the Permittee,
the state permitting authority and/or Approval Authority may,as appropriate:
i. Amend the Pennittee's CDPS discharge permit to specify the additional pollutant(s)and corresponding effluent
limitation(s)consistent with the applicable national Pretreatment Standards;
ii. Require the Permittee to specify,by ordinance,order,or other enforceable means,the type of pollutant(s)and the
maximum amount which may be discharged to the Pennittee's DWTW for treatment. Such requirement shall be
imposed in a manner consistent with the program development requirements of the General Pretreatment Regulations
at 40 CFR Part 403; and/or,
Hi. Require the Permittee to monitor its discharge for any pollutant which may likely be discharged from the Pennittee's
DWTW,should the industrial user fail to properly pretreat its waste.
The state permitting authority and the Approval Authority retains,at all times,the right to take legal action against any source
of nondomestic discharge,whether directly or indirectly controlled by the Permittee,for violations of a permit,order or
similar enforceable mechanism issued by the Permittee,violations of any Pretreatment Standard or requirement,or for failure
to discharge at an acceptable level under national standards issued by EPA under 40 CFR,chapter I,subchapter N. In those
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Permit No. CO0048445
cases where a CDPS permit violation has occurred because of the failure of the Permittee to properly develop and enforce
Pretreatment Standards and requirements as necessary to protect the DWTW,the state permitting authority and/or Approval
Authority shall hold the Pennittee and/or industrial user responsible and may take legal action against the Permittee as well as
the Industrial user(s)contributing to the permit violation.
C. DEFINITION OF TERMS
1. "Acute Toxicity"means there shall be no acute toxicity in the effluent from this discharge point. The acute toxicity limitation
is exceeded if 1)a statistically significant difference in mortality(at the 95%confidence level)is observed for either species
between the control and any dilution less than or equal to the identified IWC or 2)a species mortality in any dilution of
effluent(including 100%effluent)exceeds 50%.
2. Antidegradation limits apply as the average of all data collected for months in that group during a rolling 24-month period.
These limits become effective after data has been collected for all months in the group during the 24 months following permit
issuance. Where antidegradation groups are not indicated,data from all months will be utilized to determine the reported
value and the limit will become effective in the 24th month in which the permit is effective.
3. "Chronic toxicity",which includes lethality and growth or reproduction, occurs when the NOEC and IC25 are at an effluent
concentration less than the IWC.
4. "Composite"sample is a minimum of four(4)grab samples collected at equally spaced two(2)hour intervals and
proportioned according to flow. For a SBR type treatment system,a composite sample is defined as sampling equal aliquots
during the beginning,middle and end of a decant period, for two consecutive periods during a day(if possible).
5. "Continuous"measurement,is a measurement obtained from an automatic recording device which continually measures
provides measurements.
6. "Daily Maximum limitation" for all parameters except temperature, means the limitation for this parameter shall be applied as
an instantaneous maximum(or, for pH or DO,instantaneous minimum)value. The instantaneous value is defined as the
analytical result of any individual sample. DMRs shall include the maximum(and/or minimum)of all instantaneous values
within the calendar month. Any instantaneous value beyond the noted daily maximum limitation for the indicated parameter
shall be considered a violation of this permit.
7. "Daily Maximum Temperature(DM)"is defined in the Basic Standards and Methodologies for Surface Water 1002-31, as
the highest two-hour average water temperature recorded during a given 24-hour period. This will be determined using a
rolling 2-hour maximum temperature. If data is collected every 15 minutes,a 2 hour maximum can be determined on every
data point after the initial 2 hours of collection. Note that the time periods that overlap days(Wednesday night to Thursday
morning)do not matter as the reported value on the DMR is the greatest of all the 2-hour averages.
For example data points collected at:
08:15,08:30,08:45,09:00,09:15,09:30,09:45, 10:00,would be averaged for a single 2 hour average data point
08:30,08:45,09:00,09:15,09:30,09:45, 10:00, 10:15,would be averaged fora single 2 hour average data point
08:45,09:00,09:15,09:30,09:45, 10:00, 10:15, 10:30,would be averaged for a single 2 hour average data point
This would continue throughout the course of a calendar day. The highest of these 2 hour averages over a month would be
reported on the DMR as the daily maximum temperature. At the end/beginning of a month,the collected data should be used
for the month that contains the greatest number of minumtes in the 2-hour maximum.
Data from 11 pm to 12:59 am,would fall in the previous day. Data collected from 11:01 pm to 1:00 am would fall in the new
month.
8. "Dissolved(D)metals fraction" is defined in the Basic Standards and Methodologies for Surface Water 1002-31,as that
portion of a water and suspended sediment sample which passed through a 0.40 or 0.45 UM(micron)membrane filter.
Determinations of"dissolved"constituents are made using the filtrate. This may include some very small(colloidal)
suspended particles which passed through the membrane filter as well as the amount of substance present in true chemical
solution.
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Permit No.CO0048445
9. "Geometric mean"for E. coli bacteria concentrations,the thirty(30)day and seven(7)day averages shall be determined as
the geometric mean of all samples collected in a thirty(30)day period and the geometric mean of all samples taken in a seven
(7)consecutive day period respectively. The geometric mean may be calculated using two different methods. For the
methods shown,a,b,c,d,etc.are individual sample results,and n is the total number of samples.
Method 1:
0/0
Geometric Mean=(a*b*c*d*...) "*" -means multiply
Method 2:
Geometric Mean=antilog([log(a)+log(b)+log(c)+log(d)+...]/n)
Graphical methods,even though they may also employ the use of logarithms,may introduce significant error and may not be
used.
In calculating the geometric mean,for those individual sample results that are reported by the analytical laboratory to be"less
than" a numeric value,a value of 1 should be used in the calculations. If all individual analytical results for the month are
reported to be less than numeric values,then report"less than"the largest of those numeric values on the monthly DMR.
Otherwise,report the calculated value.
For any individual analytical result of"too numerous to count"(TNTC),that analysis shall be considered to be invalid and
another sample shall be promptly collected for analysis. If another sample cannot be collected within the same sampling
period for which the invalid sample was collected(during the same month if monthly sampling is required,during the same
week if weekly sampling is required,etc.), then the following procedures apply:
i. A minimum of two samples shall be collected for coliform analysis within the next sampling period.
ii. If the sampling frequency is monthly or less frequent: For the period with the invalid sample results,leave the spaces
on the corresponding DMR for reporting coliform results empty and attach to the DMR a letter noting that a result of
TNTC was obtained for that period,and explain why another sample for that period had not been collected.
If the sampling frequency is more frequent than monthly: Eliminate the result of TNTC from any further calculations, and use
all the other results obtained within that month for reporting purposes. Attach a letter noting that a result of TNTC was
obtained,and list all individual analytical results and corresponding sampling dates for that month.
10. "Grab" sample, is a single"dip and take"sample so as to be representative of the parameter being monitored.
11. "In-situ"measurement is defined as a single reading,observation or measurement taken in the field at the point of discharge.
12. "Instantaneous"measurement is a single reading,observation,or measurement performed on site using existing monitoring
facilities.
13. "Maximum Weekly Average Temperature(MWAT)"is defined in the Basic Standards and Methodologies for Surface Water
1002-31,as an implementation statistic that is calculated from field monitoring data. The MWAT is calculated as the largest
mathematical mean of multiple,equally spaced,daily temperatures over a seven-day consecutive period,with a minimum of
three data points spaced equally through the day. For lakes and reservoirs,the MWAT is assumed to be equivalent to the
maximum WAT from at least three profiles distributed throughout the growing season(generally July-September).
The MWAT is calculated by averaging all temperature data points collected during a calendar day,and then averaging the
daily average temperatures for 7 consecutive days. This 7 day averaging period is a rolling average, i.e.on the 8th day,the
MWAT will be the averages of the daily averages of days 2-8. The value to be reported on the DMR is the highest of all the
rolling 7-day averages throughout the month. For those days that are at the end/beginning of the month,the data shall be
reported for the month that contains 4 of the 7 days.
Day 1: Average of all temperature data collected during the calendar day.
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Permit No.CO0048445
Day 2: Average of all temperature data collected during the calendar day.
Day 3: Average of all temperature data collected during the calendar day.
Day 4: Average of all temperature data collected during the calendar day.
Day 5: Average of all temperature data collected during the calendar day.
Day 6: Average of all temperature data collected during the calendar day.
Day 7: Average of all temperature data collected during the calendar day.
I"MWAT Calculation as average of previous 7 days
Day 8: Average of all temperature data collected during the calendar day.
2"d MWAT Calculation as average of previous 7 days
Day 9: Average of all temperature data collected during the calendar day.
3rd MWAT Calculation as average of previous 7 days
14. "Potentially dissolved(PD)metals fraction"is defined in the Basic Standards and Methodologies for Surface Water 1002-31,
as that portion of a constituent measured from the filtrate of a water and suspended sediment sample that was first treated with
nitric acid to a pH of 2 or less and let stand for 8 to 96 hours prior to sample filtration using a 0.40 or 0.45-UM(micron)
membrane filter. Note the"potentially dissolved" method cannot be used where nitric acid will interfere with the analytical
procedure used for the constituent measured.
15. "Quarterly measurement frequency"means samples maybe collected at any time during the calendar quarter if a continual
discharge occurs. If the discharge is intermittent,then samples shall be collected during the period that discharge occurs.
16. "Recorder"requires the continuous operation of a chart and/or totalizer(or drinking water rotor meters or pump hour meters
where previously approved.)
17. SAR and Adjusted SAR-The equation for calculation of SAR-adj is:
Nat
SAR-adj=
'Ca, + Mg'
2
Where:
Nat=Sodium in the effluent reported in meq/I
Mg"{=Magnesium in the effluent reported in meq/I
Ca,=calcium(in meq/l)in the effluent modified due to the ratio of bicarbonate to calcium
The values for sodium(Na'),calcium(Co,bicarbonate(HCO3)and magnesium(Mg")in this equation are expressed in units of
milliequivalents per liter(meq/1). Generally,data for these parameters are reported in terms of mg/I,which must then be converted
to calculate the SAR. The conversions are:
Concentration in mg II
meq/I=
Equivalent weight in mg l meq
Where the equivalent weights are determined based on the atomic weight of the element divided by the ion's charge:
Nat=23.0 mg/meq(atomic weight of 23,charge of 1)
Ca+' =20.0 mg/meq(atomic weight of 40.078,charge of 2)
Mg"= 12.15 mg/meq(atomic weight of 24.3,charge of 2)
HCO3=61 mg/mep(atomic weight of 61,charge of 1)
The EC and the HCO3 7Ca++ratio in the effluent(calculated by dividing the HCO3 in meq/I by the Ca+`in meq/I)are used to
determine the Ca,using the following table.
Table—Modified Calcium Determination for Adjusted Sodium Adsorption Ratio
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Permit No.CO0048445
HCO3/Ca Ratio And EC 1,2,3
Salinity of Effluent(EC)(dS/m)
0.1 1 0.2 1 0.3 1 0.5 1 0.7 1 1.0 1 1.5 2.0 I 3.0 1 4.0 1 6.0 1 8.0
.051 13.20 13.61 13.921 14.40 14.79 15.26 15.91 16.431 17.28 17.97 19.07 19.94
.101 8.31 8.57 8.771 9.07 9.31 9.62 10.02 10.35[ 10.89 11.32 12.01 12.56
.15[ 6.34 6.54 6.69 6.92 7,11 7.34 7.65 7.90 8.31 8.64 9.17 9.58
.201 5.24 5.40 5.52 5.71 5.87 6.06 6.31 6.52 6.86 7.13 7.57 7.91
.251 4.51 4.65 4.76 4.92 5.06 5.22 5.44 5.62 5.91 6.15 6.52 6.82
.301 4.00 4.12 4.21 4.36 4.48 4.62 4.82 4.98 5.24 5.44 5.77 6.04
.351 3.611 3.72 3.80 3.94 4.04 4.171 4.35 4.49 4.72 4.91 5.21 5.45
.401 3.30E 3.40 3.48 3.60 3.70 3.821 3.98 4.11 4.32 4.49 4.77 4.98
.451 3.05 3.14 3.22 3.33 3.42 3.53 3.68 3.80 4.00 4.15 4.41 4.61
.501 2.84 2.93 3.00 3.10 3.19 3.29 3.43 3.54 3.72 3.87 4.11 4.30
.751 2.17 2.24 2.29 2.37 2.43 2.51 2.62 2.70 2.84 2.95 3.14 3.28
1.001 1.79 1.85 1.89 1.96 2.01 2.09 2.16 2.23 2.35 2.44 2.59 2.71
1.25 1.54 1.59 1.63 1.68 1.731 1.78 1.86 1.921 2.02 2.10 2.23 2.33
Ratio of 1.50 1.37 1.41 1.44 1.49 1.531 1.58 1.65 1.70 1.79 1.86 1.97 2.07
HCO3/Ca
1.75 1.23 1.27 1.30 1.35 1.38 1.43 1.49 1.54 1.62 1.68 1.78 1.86
2.00 1.13 1.16 1.19 1.23 1.26 1.31 1.36 1.40 1.48 1.54 1.63 1.70
2.25 1.04 1.08 1.10 1.14 1.17 1.21 1.26 1.30 1.37 1.42 1.51 1.58
2.50 0.97 1.00 1.02 1.06 1.09 1.12 1.17 1.21 1.27 1.32 1.40 1.47
3.00 0.85 0.89 0.91 0.94 0.96 1.00 1.04 1.07 1.13 1.17 1.24 1.30
3.50 0.78 0.80 0.82 0.85 0.87 0.90 0.94 0.97 1.02 1.06 1.12 1.17
4.00 0.71 0.73 0.75 0.78 0.80 0.82 0.86 0.88 0.93 0.97 1.03 1.07
4.50 0.66 0.68 0.69 0.72 0.74 0.76 0.79 0.82 0.86 0.90 0.95 0.99
5.00 0.61 0.63 0.65 0.67 0.69 0.71 0.74 0.76 0.80 0.83 0.88 0.93
7.00 0.49 0.50 0.52 0.53 0.55 0.57 0.59 0.61 0.64 0.67 0.71 0.74
10.00 0.39 0.40 0.41 0.42 0.43 0.45 0.47 0.48 0.51 0.53 0.56 0.58
20.00 0.24 0.25 0.26 0.26 0.27 0.28 0.29 0.30 0.32 0.33 0.35 0.37
30.00 0.18 0.19 0.20 0.20 0.21 0.21 0.22 0.23 0.24 0.25 0.27 0.28
Adapted from Suarez(1981).
2 Assumes a soil source of calcium from lime(CaCO3)or silicates;no precipitation of magnesium,and partial pressure of CO2 near the soil
surface(Pco2)is 0.0007 atmospheres.
Ca,,,HCO3,Ca are reported in meq/I;EC is in dS/m(deciSiemens per meter).
Because values will not always be quantified at the exact EC or HCO3-/Ca++ratio in the table, the resulting Cax must be
determined based on the closest value to the calculated value. For example,for a calculated EC of 2.45 dS/m,the column for the
EC of 2.0 would be used. However, for a calculated EC of 5.1, the corresponding column for the EC of 6.0 would be used.
Similarly, for a HCO3-/Ca'ratio of 25.1,the row for the 30 ratio would be used.
The Division acknowledges that some effluents may have electrical conductivity levels that fall outside of this table,and others
have bicarbonate to calcium ratios that fall outside this table. For example,some data reflect HCO3-/Ca++ratios greater than 30
due to bicarbonate concentrations reported greater than 1000 mg/I versus calcium concentrations generally less than 10 mg/1(i.e.,
corresponding to HCO3-/Ca++ratios greater than 100). Despite these high values exceeding the chart's boundaries,it is noted that
the higher the HCO3-/Ca++ratio,the greater the SAR-adj. Thus,using the Ca„values corresponding to the final row containing
bicarbonate/calcium ratios of 30,the permittee will actually calculate an SAR-adj that is less than the value calculated if additional
rows reflecting HCO3-/Ca++ratios of greater than 100 were added.
18. "Seven(7)day average"means,with the exception of fecal coliform or E. co/i bacteria(see geometric mean),the arithmetic
mean of all samples collected in a seven(7)consecutive day period. When calculating the 7-day average,a value of zero
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Permit No. CO0048445
should be used in place of any value that is less than the reporting limit. If all values are less than the PQL,and the PQL is
greater than the permit limit"BDL"should be reported. If all values are less than the PQL,and the PQL is less than
or equal to the permit limit,"<x"should be reported,where"x"is the reporting limit. Otherwise,the calculated
average shall be reported. Note that it does not matter if a calculated average is greater or less than the PQL,it must
be reported as a value. Such seven(7)day averages shall be calculated for all calendar weeks,which are defined as
beginning on Sunday and ending on Saturday. If the calendar week overlaps two months(i.e.the Sunday is in one month and
the Saturday in the following month),the seven(7)day average calculated for that calendar week shall be associated with the
month that contains the Saturday. Samples may not be used for more than one(1)reporting period.
19. "Thirty(30)day average" means,except for fecal coliform or E. coli bacteria(see geometric mean),the arithmetic mean of all
samples collected during a thirty(30)consecutive-day period. When calculating the 30-day average,a value of zero should
be used in place of any value that is less than the PQL. If all values are less than the PQL,and the PQL is greater than
the permit limit"BDL"should be reported. If all values are less than the PQL,and the PQL is less than or equal to
the permit limit,"<x"should be reported,where"x"is the reporting limit. Otherwise,the calculated average shall be
reported. Note that it does not matter if a calculated average is greater or less than the PQL,it must be reported as a
value. The permittee shall report the appropriate mean of all self-monitoring sample data collected during the calendar month
on the Discharge Monitoring Reports. Samples shall not be used for more than one(1)reporting period.
20. "Total Inorganic Nitrogen(T.I.N.)"is an aggregate parameter determined based on ammonia,nitrate and nitrite
concentrations. Given that there are no approved analytical procedures for determining T.I.N. itself as an aggregate
parameter,daily maximum and 30-day average concentrations for T.I.N.shall be determined using the calculated T.I.N.
concentrations versus T.I.N. analytical results. Specifically,the facility must monitor for total ammonia and total nitrate plus
nitrite on the same days. The calculated T.I.N.concentrations in mg/L shall then be determined as the sum of the analytical
results of same-day sampling for total ammonia(as N)in mg/L,and total nitrate plus nitrite(as N)in mg/L. From these
calculated T.I.N. concentrations in mg/L,the daily maximum and 30-day average concentrations must then be determined in
the same manner as the previously set out definitions.
21. "Total Metals" means the concentration of metals determined on an unfiltered sample following vigorous digestion(Section
4.1.3),or the sum of the concentrations of metals in both the dissolved and suspended fractions,as described in Manual of
Methods for Chemical Analysis of Water and Wastes,U.S. Environmental Protection Agency,March 1979,or its equivalent.
22. "Total Recoverable Metals"means that portion of a water and suspended sediment sample measured by the total recoverable
analytical procedure described in Methods for Chemical Analysis of Water and Wastes U.S. Environmental Protection
Agency,March 1979 or its equivalent.
23. "Twenty four(24)hour composite" sample is a combination of at least eight(8)sample aliquots of at least 100 milliliters,
collected at equally spaced intervals during the operating hours of a facility over a twenty-four(24)hour period. For volatile
pollutants,aliquots must be combined in the laboratory immediately before analysis. The composite must be flow
proportional;either the time interval between each aliquot or the volume of each aliquot must be proportional to either the
wastewater or effluent flow at the time of sampling or the total wastewater or effluent flow since the collection of the previous
aliquot. Aliquots may be collected manually or automatically.
24. "Twice Monthly" monitoring frequency means that two samples shall be collected each calendar month on separate weeks
with at least one full week between the two sample dates. Also,there shall be at least one full week between the second
sample of a month and the first sample of the following month.
25. "Visual" observation is observing the discharge to check for the presence of a visible sheen or floating oil.
26. "Water Quality Control Division" or"Division" means the state Water Quality Control Division as established in 25-8-101 et
al.)
Additional relevant definitions are found in the Colorado Water Quality Control Act,CRS §§ 25-8-101 et seq.,the Colorado
Discharge Permit System Regulations,Regulation 61 (5 CCR 1002-61)and other applicable regulations.
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Permit No. CO0048445
D. GENERAL MONITORING,SAMPLING AND REPORTING REQUIREMENTS
1. Routine Reporting of Data
Reporting of the data gathered in compliance with Part I.B.1 shall be on a monthly basis. Reporting of all data gathered shall
comply with the requirements of Part I.D. (General Requirements). Monitoring results shall be summarized for each calendar
month and reported on Division approved discharge monitoring report(DMR)forms(EPA form 3320-1).
The permittee must submit these forms either by mail,or by using the Division's Net-DMR service(when available). If
mailed,one form shall be mailed to the Division,as indicated below,so that the DMR is received no later than the 28th day of
the following month(for example,the DMR for the first calendar quarter must be received by the Division by April 28th). If
no discharge occurs during the reporting period, "No Discharge" shall be reported.
The original signed copy of each discharge monitoring report(DMR)shall be submitted to the Division at the following
address:
Colorado Department of Public Health and Environment
Water Quality Control Division
WQCD-P-B2
4300 Cherry Creek Drive South
Denver,Colorado 80246-1530
The Discharge Monitoring Report forms shall be filled out accurately and completely in accordance with requirements of this
permit and the instructions on the forms. They shall be signed by an authorized person as identified in Part I.D.B.
2. Annual Biosolids Report
The permittee shall provide the results of all biosolids monitoring and information on management practices,land application
sites,site restrictions and certifications. Such information shall be provided no later than February 19th of each year.
Reports shall be submitted addressing all such activities that occurred in the previous calendar year. If no biosolids were
applied to the land during the reporting period,"no biosolids applied" shall be reported.Until further notice,biosolids
monitoring results shall be reported on forms,or copies of forms,provided by the Division. Annual Biosolids Reports
required herein,shall be signed and certified in accordance with the Signatory Requirements,Part I.D.1,and submitted as
follows:
The original copy of each form shall be submitted to the following address:
COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT,
WATER QUALITY CONTROL DIVISION
WQCD-PERMITS-B2
4300 CHERRY CREEK DRIVE SOUTH
DENVER,COLORADO 80246-1530
A copy of each form shall be submitted to the following address:
WATER PROGRAM REGIONAL BIOSOLIDS PROGRAM
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION VIII,
1595 WYNKOOP STREET
DENVER,CO 80202-2466
ATTENTION: BIOSOLIDS PROGRAM MANAGER
3. Representative Sampling
Samples and measurements taken for the respective identified monitoring points as required herein shall be representative of
the volume and nature of: 1)all influent wastes received at the facility,including septage,biosolids,etc.;2)the monitored
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Permit No. CO0048445
effluent discharged from the facility;and 3)biosolids produced at the facility. All samples shall be taken at the monitoring
points specified in this permit and,unless otherwise specified,before the influent,effluent,or biosolids wastestream joins or
is diluted by any other wastestream,body of water,or substance. Monitoring points shall not be changed without notification
to and prior approval by the Division.
4. Influent and Effluent Sampling Points
Influent and effluent sampling points shall be so designed or modified so that: 1)a sample of the influent can be obtained after
preliminary treatment and prior to primary or biological treatment and 2)a sample of the effluent can be obtained at a point
after the final treatment process and prior to discharge to state waters. The permittee shall provide access to the Division to
sample at these points.
5. Analytical and Sampling Methods for Monitoring
The permittee shall install,calibrate,use and maintain monitoring methods and equipment,including biological and indicated
pollutant monitoring methods. All sampling shall be performed by the permittee according to specified methods in 40 C.F.R.
Part 136;methods approved by EPA pursuant to 40 C.F.R. Part 136; or methods approved by the Division,in the absence of a
method specified in or approved pursuant to 40 C.F.R.Part 136.
If the permit contains a numeric effluent limit,the analytical method and PQL selected for a parameter shall be the
one that can measure compliance with the numeric effluent limit.If all analytical methods and corresponding PQLs
are greater than the numeric effluent limit,then the analytical method with the lowest PQL shall be used.
If the permit contains a monitoring or report only requirement,the analytical method chosen shall be one that can
measure to the potential numeric effluent limit(s)(maximum allowable pollutant concentration as shown in the WQA
or fact sheet).If all analytical methods and corresponding PQLs are greater than the potential numeric effluent limit
(s),then the analytical method with the lowest PQL shall be used.
If the permit contains an interim effluent limitation(a limit is report until such time as a numeric effluent limit
becomes effective),the analytical method chosen shall be one that can measure to the final numeric effluent limit.If all
analytical methods and corresponding PQLs are greater than the final numeric effluent limit(s),then the analytical
method with the lowest PQL shall be used.
For parameters such as TIN,the analytical methods chosen shall be those that can measure to the potential or final
numeric effluent limit,based on the sum of the PQLs for nitrate,nitrite and ammonia.
When the analytical method which complies with the above requirements has a PQL greater than the permit limit,the
permittee shall report "BDL" on the DMR. Such reports will not be considered as violations of the permit limit,as
long as the lowest available PQL is used for the analysis. When the analytical method which complies with the above
requirements has a PQL that is equal to or less than the permit limitation,"<X"(where X=the actual PQL achieved
by the laboratory)shall be reported on the DMR. For parameters that have only a monitoring or report only
limitation,"<X"(where X=the actual PQL achieved by the laboratory)shall be reported on the DMR.
The present lowest PQLs for specific parameters,as determined by the State Laboratory(November 2008)are provided
below. If the analytical method cannot achieve a PQL that is less than or equal to the permit limit,then the method,or a more
precise method,must achieve a PQL that is less than or equal to the PQL in the table below. A listing of the PQLs for organic
parameters that must meet the above requirement can be found in the Division's Practical Quantitation Limitation Guidance
Document,July 2008.
These limits apply to the total recoverable or the potentially dissolved fraction of metals.
For hexavalent chromium,samples must be unacidified so dissolved concentrations will be measured rather than potentially
dissolved concentrations.
In the calculation of average concentrations,those analytical results that are less than the practical quantitation limit shall be
considered to be zero for calculation purposes. If all individual analytical results that would be used in the calculations are
below the practical quantitation limit,then"less than x",where x is the practical quantitation limit,shall be reported on the
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Permit No. CO0048445
monthly DMR. Otherwise,report the calculated value.
Parameter Practical Parameter Practical
Quantitation Quantitation
Limits, Limits,µg/I
Aluminum 50 µg/I Manganese 2 µg/1
Ammonia 1 mg/I Mercury 0.1 µg/l
Arsenic 1 µg/I Mercury(low-level) 0.003 µg/I
Barium 5µg/1 Nickel 50 µg/1
Beryllium 1 µg/1 N-Ammonia 50 µg/1
BOD/CBOD 1 mg/I N Nitrate/Nitrite 0.5 mg/I
Boron 50 µg/I N-Nitrate 50 µg/I
Cadmium 1 µg/I N-Nitrite 10 µg/I
Calcium 20 µg/I Total Nitrogen 0.5 mg/1
Chloride 2 mg/I Phenols 100 µg/I
Chlorine 0.1 mg/I Phosphorus 10 µg/1
Total Residual Chlorine Radium 226 1 pCi/I
DPD colorimetric 0.10 mg/I Radium 228 1 pCi/1
Amperometric titration 0.05 mg/I Selenium 1 µg/I
Chromium 20 µg/I Silver 0.5 µg/I
Chromium,Hexavalent 20 µg/I Sodium 0.2 mg/I
Copper 5 µg/I Sulfate 5 mg/1
Cyanide(Direct/Distilled) 10 µg/I Sulfide 0.2 mg/I
Cyanide,WAD+A47 5 µg/I Total Dissolved Solids 10 mg/I
Fluoride 0.1 mg/I Total Suspended Solids 10 mg/I
Iron 10µg/l Thallium 1 µg/I
Lead 1 µg/l Uranium 1 µg/1
Magnesium 20 µg/I Zinc 10 µg/I
6. Records
a. The permittee shall establish and maintain records. Those records shall include,but not be limited to,the following:
i. The date,type,exact place,and time of sampling or measurements;
ii. The individual(s)who performed the sampling or measurements;
iii. The date(s)the analyses were performed;
iv. The individual(s)who performed the analyses;
v. The analytical techniques or methods used;and
vi. The results of such analyses.
b. The permittee shall retain for a minimum of three(3)years records of all monitoring information,including all original
strip chart recordings for continuous monitoring instrumentation,all calibration and maintenance records,copies of all
reports required by this permit and records of all data used to complete the application for this permit.This period of
retention shall be extended during the course of any unresolved litigation regarding the discharge of pollutants by the
permittee or when requested by the Division or Regional Administrator.
7. Flow Measuring Devices
Unless exempted in Part I.A.2 of this permit,flow metering at the headworks shall be provided to give representative values
of throughput and treatment of the wastewater system. The metering device shall be equipped with a local flow indication
instrument and a flow indication-recording-totalization device suitable for providing permanent flow records,which should be
in the plant control building.
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Permit No. CO0048445
For mechanical facilities,where influent flow metering is not practical and the same results may be obtained from metering at
the effluent end of the treatment facility,this type of flow metering arrangement will be considered,and if approved,noted in
Part I.A.2 of this permit. For lagoons,an instantaneous or continuous effluent flow measuring device shall be required in
addition to the above described influent flow measuring device.
At the request of the Division,the permittee must be able to show proof of the accuracy of any flow-measuring device used in
obtaining data submitted in the monitoring report. The flow-measuring device must indicate values within ten(10)percent of
the actual flow entering the facility.
8. Signatory Requirements
a. All reports and other information required by the Division,shall be signed and certified for accuracy by the permittee in
accord with the following criteria:
i) In the case of corporations,by a responsible corporate officer. For purposes of this section, the responsible
corporate officer is responsible for the overall operation of the facility from which the discharge described in the
form originates;
ii) In the case of a partnership,by a general partner;
iii) In the case of a sole proprietorship,by the proprietor;
iv) In the case of a municipal,state,or other public facility,by either a principal executive officer,or ranking elected
official. For purposes of this section,a principal executive officer has responsibility for the overall operation of the
facility from which the discharge originates;
v) By a duly authorized representative of a person described above,only if:
1) The authorization is made in writing by a person described in i,ii,iii,or iv above;
2) The authorization specifies either an individual or a position having responsibility for the overall operation of
the regulated facility or activity such as the position of plant manager,operator of a well or a well field,
superintendent,position of equivalent responsibility,or an individual or position having overall responsibility
for environmental matters for the company. (A duly authorized representative may thus be either a named
individual or any individual occupying a named position);and,
3) The written authorization is submitted to the Division.
b. If an authorization as described in this section is no longer accurate because a different individual or position has
responsibility for the overall operation of the facility,a new authorization satisfying the requirements of this section must
be submitted to the Division prior to or together with any reports,information,or applications to be signed by an
authorized representative.
The permittee,or the duly authorized representative shall make and sign the following certification on all such
documents:
"I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in
accordance with a system designed to assure that qualified personnel properly gather and evaluate the information
submitted. Based on my inquiry of the person or persons who manage the system,or those persons directly responsible
for gathering the information,the information submitted is to the best of my knowledge and belief,true,accurate and
complete. I am aware that there are significant penalties for submitting false information,including the possibility of fine
and imprisonment for knowing violations."
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Permit No. CO0048445
PART II
A. NOTIFICATION REQUIREMENTS
1. Notification to Parties
All notification requirements under this section shall be directed as follows:
a. Oral Notifications,during normal business hours shall be to:
Water Quality Protection Section-Domestic Compliance Program
Water Quality Control Division
Telephone: (303)692-3500
b. Written notification shall be to:
Water Quality Protection Section-Domestic Compliance Program
Water Quality Control Division
Colorado Department of Public Health and Environment
WQCD-WQP-B2
4300 Cherry Creek Drive South
Denver,CO 80246-1530
2. Change in Discharge
The permittee shall notify the Division, in writing,of any planned physical alterations or additions to the permitted facility.
Notice is required only when:
a. The alteration or addition could significantly change the nature or increase the quantity of pollutants discharged,or;
b. The alteration or addition results in a significant change in the permittee's sludge use or disposal practices,and such
alteration,addition,or change may justify the application of permit conditions that are different from or absent in the
existing permit,including notification of additional use or disposal sites not reported pursuant to an approved land
application plan.
The permittee shall give advance notice to the Division of any planned changes in the permitted facility or activity which may
result in noncompliance with permit requirements.
Whenever notification of any planned physical alterations or additions to the permitted facility is required pursuant to this
section,the permittee shall furnish the Division such plans and specifications which the Division deems reasonably necessary
to evaluate the effect on the discharge,the stream,or ground water. If the Division finds that such new or altered discharge
might be inconsistent with the conditions of the permit,the Division shall require a new or revised permit application and
shall follow the procedures specified in Sections 61.5 through 61.6,and 61.15 of the Colorado Discharge Permit System
Regulations.
3. Special Notifications_Definitions
a. Bypass: The intentional diversion of waste streams from any portion of a treatment facility.
b. Severe Property Damage: Substantial physical damage to property at the treatment facilities which causes them to
become inoperable,or substantial and permanent loss of natural resources which can reasonably be expected to occur in
the absence of a bypass. It does not mean economic loss caused by delays in production.
c. Upset: An exceptional incident in which there is unintentional and temporary noncompliance with permit effluent
limitations because of factors beyond the reasonable control of the permittee. An upset does not include noncompliance
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Permit No. CO0048445
to the extent caused by operational error,improperly designed treatment facilities,inadequate treatment facilities,lack of
preventative maintenance,or careless or improper operation.
4. Noncompliance Notification
a. If,for any reason,the permittee does not comply with or will be unable to comply with any discharge limitations or
standards specified in this permit,the permittee shall,at a minimum,provide the Division and EPA with the following
information:
i) A description of the discharge and cause of noncompliance;
ii) The period of noncompliance, including exact dates and times and/or the anticipated time when the discharge will
return to compliance;and
iii) Steps being taken to reduce,eliminate,and prevent recurrence of the noncomplying discharge.
b. The permittee shall report the following circumstances orally within twenty-four(24)hours from the time the pennittee
becomes aware of the circumstances,and shall mail to the Division a written report containing the information requested
in Part II.A.4(a)within five(5)days after becoming aware of the following circumstances:
i) Circumstances leading to any noncompliance which may endanger health or the environment regardless of the cause
of the incident;
ii) Circumstances leading to any unanticipated bypass which exceeds any effluent limitations in the permit;
iii) Circumstances leading to any upset which causes an exceedance of any effluent limitation in the permit;
iv) Daily maximum violations for any of the pollutants limited by Part I.A of this permit and specified as requiring 24-
hour notification. This includes any toxic pollutant or hazardous substance or any pollutant specifically identified as
the method to control any toxic pollutant or hazardous substance.
c. The permittee shall report instances of non-compliance which are not required to be reported within 24-hours at the time
Discharge Monitoring Reports are submitted. The reports shall contain the information listed in sub-paragraph(a)of this
section.
5. Other Notification Requirements
Reports of compliance or noncompliance with,or any progress reports on,interim and final requirements contained in any
compliance schedule in the permit shall be submitted no later than fourteen(14)days following each scheduled date,unless
otherwise provided by the Division.
The permittee shall notify the Division,in writing,thirty(30)days in advance of a proposed transfer of permit as provided in
Part II.B.3.
The pennittee's notification of all anticipated noncompliance does not stay any permit condition.
All existing manufacturing,commercial,mining,and silvicultural dischargers must notify the Division as soon as they know
or have reason to believe:
a. That any activity has occurred or will occur which would result in the discharge,on a routine or frequent basis,of any
toxic pollutant which is not limited in the permit,if that discharge will exceed the highest of the following"notification
levels":
i) One hundred micrograms per liter(100 µg/1);
ii) Two hundred micrograms per liter(200 µg/I)for acrolein and acrylonitrile; five hundred micrograms per liter(500
µg/1)for 2.4-dinitrophenol and 2-methyl-4.6-dinitrophenol; and one milligram per liter(1.0 mg/I)for antimony;
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Permit No. CO0048445
iii) Five(5)times the maximum concentration value reported for that pollutant in the permit application in accordance
with Section 61.4(2)(g).
iv) The level established by the Division in accordance with 40 C.F.R. § 122.44O).
b. That any activity has occurred or will occur which would result in any discharge,on a non-routine or infrequent basis,of
a toxic pollutant which is not limited in the permit, if that discharge will exceed the highest of the following"notification
levels":
i) Five hundred micrograms per liter(500 µg/l);
ii) One milligram per liter(1 mg/I)for antimony;and
iii) Ten(10)times the maximum concentration value reported for that pollutant in the permit application.
iv) The level established by the Division in accordance with 40 C.F.R. § 122.44(O.
6. Bypass Notification
If the permittee knows in advance of the need for a bypass,a notice shall be submitted,at least ten days before the date of the
bypass,to the Division. The bypass shall be subject to Division approval and limitations imposed by the Division. Violations
of requirements imposed by the Division will constitute a violation of this permit.
7. Upsets
a. Effect of an Upset
An upset constitutes an affirmative defense to an action brought for noncompliance with permit effluent limitations if the
requirements of paragraph(b)of this section are met. No determination made during administrative review of claims that
noncompliance was caused by upset,and before an action for noncompliance, is final administrative action subject to
judicial review.
b. Conditions Necessary for a Demonstration of Upset
A permittee who wishes to establish the affirmative defense of upset shall demonstrate through properly signed
contemporaneous operating logs,or other relevant evidence that:
i) An upset occurred and that the permittee can identify the specific cause(s)of the upset; and
ii) The permitted facility was at the time being properly operated and maintained;and
iii) The pennittee submitted proper notice of the upset as required in Part II.A.4.of this permit(24-hour notice);and
iv) The permittee complied with any remedial measure necessary to minimize or prevent any discharge or sludge use or
disposal in violation of this permit which has a reason able likelihood of adversely affecting human health or the
environment.
In addition to the demonstration required above,a permittee who wishes to establish the affirmative defense of upset for a
violation of effluent limitations based upon water quality standards shall also demonstrate through monitoring,modeling
or other methods that the relevant standards were achieved in the receiving water.
c. Burden of Proof
In any enforcement proceeding the permittee seeking to establish the occurrence of an upset has the burden of proof.
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Permit No. CO0048445
8. Discharge Point
Any discharge to the waters of the State from a point source other than specifically authorized by this permit is prohibited.
9. Proper Operation and Maintenance
The pennittee shall at all times properly operate and maintain all facilities and systems of treatment and control including all
portions of the collection system and lift stations owned by the permittee(and related appurtenances)which are installed or
used by the pennittee as necessary to achieve compliance with the conditions of this permit. Proper operation and
maintenance includes effective performance and adequate laboratory and process controls,including appropriate quality
assurance procedures(40 CFR 122.41(e). This provision requires the operation of back-up or auxiliary facilities or similar
systems which are installed by the permittee only when necessary to achieve compliance with the conditions of the permit.
10. Minimization of Adverse Impact
The permittee shall take all reasonable steps to minimize or prevent any discharge of sludge use or disposal in violation of this
permit which has a reasonable likelihood of adversely affecting human health or the environment. As necessary,accelerated
or additional monitoring to determine the nature and impact of the noncomplying discharge is required.
11. Removed Substances
Solids, sludges,or other pollutants removed in the course of treatment or control of wastewaters shall be disposed in
accordance with applicable state and federal regulations.
For all domestic wastewater treatment works,at industrial facilities,the permittee shall dispose of sludge in accordance with
all State and Federal regulations.
12. Submission of Incorrect or Incomplete Information
Where the permittee failed to submit any relevant facts in a permit application,or submitted incorrect information in a permit
application or report to the Division,the pennittee shall promptly submit the relevant information which was not submitted or
any additional information needed to correct any erroneous information previously submitted.
13. Bypass
a. Bypasses are prohibited and the Division may take enforcement action against the permittee for bypass,unless:
i) The bypass is unavoidable to prevent loss of life,personal injury,or severe property damage;
ii) There were no feasible alternatives to bypass such as the use of auxiliary treatment facilities,retention of untreated
wastes,or maintenance during normal periods of equipment downtime. This condition is not satisfied if adequate
back-up equipment should have been installed in the exercise of reasonable engineering judgment to prevent a
bypass which occurred during normal periods of equipment downtime or preventive maintenance;and
iii) Proper notices were submitted in compliance with Part II.A.4.
b. "Severe property damage"as used in this Subsection means substantial physical damage to the treatment facilities which
causes them to become inoperable,or substantial and permanent loss of natural resources which can reasonably be
expected to occur in the absence of a bypass. Severe property damage does not mean economic loss caused by delays in
production.
c. The permittee may allow a bypass to occur which does not cause effluent limitations to be exceeded,but only if it also is
for essential maintenance or to assure optimal operation. These bypasses are not subject to the provisions of paragraph
(a)above.
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Permit No. CO0048445
d. The Division may approve an anticipated bypass,after considering adverse effects, if the Division determines that the
bypass will meet the conditions specified in paragraph(a)above.
14. Reduction,Loss,or Failure of Treatment Facility.
The permittee has the duty to halt or reduce any activity if necessary to maintain compliance with the effluent limitations of
the permit. Upon reduction, loss,or failure of the treatment facility,the permittee shall,to the extent necessary to maintain
compliance with its permit,control production,control sources of wastewater,or all discharges,until the facility is restored or
an alternative method of treatment is provided. This provision also applies to power failures,unless an alternative power
source sufficient to operate the wastewater control facilities is provided.
It shall not be a defense for a permittee in an enforcement action that it would be necessary to halt or reduce the permitted
activity in order to maintain compliance with the conditions of this permit.
B. RESPONSIBILITIES
I. Inspections and Right to Entry
The permittee shall allow the Division and/or the authorized representative,upon the presentation of credentials:
a. To enter upon the permittee's premises where a regulated facility or activity is located or in which any records are
required to be kept under the terms and conditions of this permit;
b. At reasonable times to have access to and copy any records required to be kept under the terms and conditions of this
permit and to inspect any monitoring equipment or monitoring method required in the permit;and
c. To enter upon the permittee's premises in a reasonable manner and at a reasonable time to inspect and/or investigate,any
actual,suspected,or potential source of water pollution,or to ascertain compliance or non compliance with the Colorado
Water Quality Control Act or any other applicable state or federal statute or regulation or any order promulgated by the
Division. The investigation may include,but is not limited to,the following: sampling of any discharge and/or process
waters,the taking of photographs, interviewing of any person having knowledge related to the discharge permit or alleged
violation,access to any and all facilities or areas within the pennittee's premises that may have any affect on the
discharge,permit,or alleged violation. Such entry is also authorized for the purpose of inspecting and copying records
required to be kept concerning any effluent source.
d. The permittee shall provide access to the Division to sample the discharge at a point after the final treatment process but
prior to the discharge mixing with state waters upon presentation of proper credentials.
In the making of such inspections, investigations,and determinations,the Division, insofar as practicable,may designate as its
authorized representatives any qualified personnel of the Department of Agriculture. The Division may also request
assistance from any other state or local agency or institution.
2. Duty to Provide Information
The permittee shall furnish to the Division,within a reasonable time,any information which the Division may request to
determine whether cause exists for modifying,revoking and reissuing,or terminating this permit,or to determine compliance
with this permit. The permittee shall also furnish to the Division,upon request,copies of records required to be kept by this
permit.
3. Transfer of Ownership or Control
a. Except as provided in paragraph b. of this section,a permit may be transferred by a permittee only if the permit has been
modified or revoked and reissued as provided in Section 61.8(8)of the Colorado Discharge Permit System Regulations,
to identify the new permittee and to incorporate such other requirements as may be necessary under the Federal Act.
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Permit No. CO0048445
b. A permit may be automatically transferred to a new permittee if:
i) The current pernittee notifies the Division in writing 30 days in advance of the proposed transfer date;and
ii) The notice includes a written agreement between the existing and new permittee(s)containing a specific date for
transfer of permit responsibility,coverage and liability between them; and
iii) The Division does not notify the existing permittee and the proposed new permittee of its intent to modify,or revoke
and reissue the permit.
iv) Fee requirements of the Colorado Discharge Permit System Regulations, Section 61.15, have been met.
4. Availability of Reports
Except for data determined to be confidential under Section 308 of the Federal Clean Water Act and the Colorado Discharge
Permit System Regulations 5 CCR 1002-61,Section 61.5(4),all reports prepared in accordance with the terms of this permit
shall be available for public inspection at the offices of the Division and the Environmental Protection Agency.
The name and address of the permit applicant(s)and permittee(s),permit applications,permits and effluent data shall not be
considered confidential. Knowingly making false statement on any such report may result in the imposition of criminal
penalties as provided for in Section 309 of the Federal Clean Water Act,and Section 25-8-610 C.R.S.
5. Modification,Suspension.Revocation,or Termination of Permits y the Division
The filing of a request by the permittee for a permit modification,revocation and reissuance,termination or a notification of
planned changes or anticipated noncompliance,does not stay any permit condition.
a. A permit may be modified, suspended,or terminated in whole or in part during its term for reasons determined by the
Division including,but not limited to,the following:
i) Violation of any terms or conditions of the permit;
ii) Obtaining a permit by misrepresentation or failing to disclose any fact which is material to the granting or denial of a
permit or to the establishment of terms or conditions of the permit;or
iii) Materially false or inaccurate statements or information in the permit application or the permit.
iv) A determination that the permitted activity endangers human health or the classified or existing uses of state waters
and can only be regulated to acceptable levels by permit modifications or termination.
b. A permit may be modified in whole or in part for the following causes,provided that such modification complies with the
provisions of Section 61.10 of the Colorado Discharge Permit System Regulations:
i) There are material and substantial alterations or additions to the permitted facility or activity which occurred after
permit issuance which justify the application of permit conditions that are different or absent in the existing permit.
ii) The Division has received new information which was not available at the time of permit issuance(other than revised
regulations,guidance,or test methods)and which would have justified the application of different permit conditions
at the time of issuance. For permits issued to new sources or new dischargers,this cause includes information
derived from effluent testing required under Section 61.4(7)(e)of the Colorado Discharge Permit System
Regulations. This provision allows a modification of the permit to include conditions that are less stringent than the
existing permit only to the extent allowed under Section 61.10 of the Colorado Discharge Permit System
Regulations.
Permit,Part II
Page 28 of 34
Permit No. CO0048445
iii) The standards or regulations on which the permit was based have been changed by promulgation of amended
standards or regulations or by judicial decision after the permit was issued. Permits may be modified during their
terms for this cause only as follows:
(A) The permit condition requested to be modified was based on a promulgated effluent limitation guideline, EPA
approved water quality standard,or an effluent limitation set forth in 5 CCR 1002-62, § 62 et seq.;and
(B) EPA has revised,withdrawn,or modified that portion of the regulation or effluent limitation guideline on which
the permit condition was based,or has approved a Commission action with respect to the water quality standard
or effluent limitation on which the permit condition was based;and
(C) The permittee requests modification after the notice of final action by which the EPA effluent limitation
guideline,water quality standard,or effluent limitation is revised,withdrawn,or modified;or
(D) For judicial decisions,a court of competent jurisdiction has remanded and stayed EPA promulgated regulations
or effluent limitation guidelines,if the remand and stay concern that portion of the regulations or guidelines on
which the permit condition was based and a request is filed by the permittee in accordance with this Regulation,
within ninety(90)days of judicial remand.
iv) The Division determines that good cause exists to modify a permit condition because of events over which the
permittee has no control and for which there is no reasonable available remedy.
v) The permittee has received a variance.
vi) When required to incorporate applicable toxic effluent limitation or standards adopted pursuant to§ 307(a)of the
Federal act.
vii) When required by the reopener conditions in the permit.
viii)As necessary under 40 C.F.R.403.8(e),to include a compliance schedule for the development of a pretreatment
program.
ix) When the level of discharge of any pollutant which is not limited in the permit exceeds the level which can be
achieved by the technology-based treatment requirements appropriate to the permittee under Section 61.8(2)of the
Colorado Discharge Permit System Regulations.
x) To establish a pollutant notification level required in Section 61.8(5)of the Colorado Discharge Permit System
Regulations.
xi) To correct technical mistakes,such as errors in calculation,or mistaken interpretations of law made in determining
permit conditions,to the extent allowed in Section 61.10 of the Colorado State Discharge Permit System
Regulations.
xii) When required by a permit condition to incorporate a land application plan for beneficial reuse of sewage sludge,to
revise an existing land application plan,or to add a land application plan.
xiii) For any other cause provided in Section 61.10 of the Colorado Discharge Permit System Regulations.
c. At the request of a permittee,the Division may modify or terminate a permit and issue a new permit if the following
conditions are met:
i) The Regional Administrator has been notified of the proposed modification or termination and does not object in
writing within thirty(30)days of receipt of notification,
ii) The Division finds that the permittee has shown reasonable grounds consistent with the Federal and State statutes
and regulations for such modifications or termination;
Permit,Part II
Page 29 of 34
Permit No. CO0048445
iii) Requirements of Section 61.15 of the Colorado Discharge Permit System Regulations have been met,and
iv) Requirements of public notice have been met.
d. Permit modification(except for minor modifications),termination or revocation and reissuance actions shall be subject to
the requirements of Sections 61.5(2),61.5(3),61.6,61.7 and 61.15 of the Colorado Discharge Permit System
Regulations. The Division shall act on a permit modification request,other than minor modification requests,within 180
days of receipt thereof Except for minor modifications,the terms of the existing permit govern and are enforceable until
the newly issued permit is formally modified or revoked and reissued following public notice.
e. Upon consent by the permittee,the Division may make minor permit modifications without following the requirements of
Sections 61.5(2),61.5(3),61.7, and 61.15 of the Colorado Discharge Permit System Regulations. Minor modifications to
permits are limited to:
i) Correcting typographical errors;or
ii) Increasing the frequency of monitoring or reporting by the permittee;or
iii) Changing an interim date in a schedule of compliance,provided the new date of compliance is not more than 120
days after the date specific in the existing permit and does not interfere with attainment of the final compliance date
requirement;or
iv) Allowing for a transfer in ownership or operational control of a facility where the Division determines that no other
change in the permit is necessary,provided that a written agreement containing a specific date for transfer of permit
responsibility,coverage and liability between the current and new permittees has been submitted to the Division; or
v) Changing the construction schedule for a discharger which is a new source,but no such change shall affect a
discharger's obligation to have all pollution control equipment installed and in operation prior to discharge;or
vi) Deleting a point source outfall when the discharge from that outfall is terminated and does not result in discharge of
pollutants from other outfalls except in accordance with permit limits.
f When a permit is modified,only the conditions subject to modification are reopened. If a permit is revoked and reissued,
the entire permit is reopened and subject to revision and the permit is reissued for a new tern.
g. The filing of a request by the permittee for a permit modification,revocation and reissuance or termination does not stay
any permit condition.
h. All permit modifications and reissuances are subject to the antibacksliding provisions set forth in 61.10(e) through(g).
6. Oil and Hazardous Substance Liability
Nothing in this permit shall be construed to preclude the institution of any legal action or relieve the permittee from any
responsibilities,liabilities,or penalties to which the permittee is or may be subject to under Section 311 (Oil and Hazardous
Substance Liability)of the Clean Water Act.
7. State Laws
Nothing in this permit shall be construed to preclude the institution of any legal action or relieve the permittee from any
responsibilities, liabilities,or penalties established pursuant to any applicable State law or regulation under authority granted
by Section 510 of the Clean Water Act. Nothing in this permit shall be construed to prevent or limit application of any
emergency power of the division.
8. Permit Violations
Permit,Part II
Page 30 of 34
Permit No. CO0048445
Failure to comply with any terms and/or conditions of this permit shall be a violation of this permit. The discharge of any
pollutant identified in this permit more frequently than or at a level in excess of that authorized shall constitute a violation of
the permit. Except as provided in Part I.D and Part II.A or B,nothing in this permit shall be construed to relieve the permittee
from civil or criminal penalties for noncompliance(40 CFR 122.41(a)(1)).
9. Property Rights
The issuance of this permit does not convey any property or water rights in either real or personal property,or stream flows,
or any exclusive privileges,nor does it authorize any injury to private property or any invasion of personal rights,nor any
infringement of Federal, State or local laws or regulations.
10. Severability,
The provisions of this permit are severable. If any provisions of this permit,or the application of any provision of this permit
to any circumstance, is held invalid,the application of such provision to other circumstances and the application of the
remainder of this permit shall not be affected.
11. Renewal Application
If the permittee desires to continue to discharge,a permit renewal application shall be submitted at least one hundred eighty
(180)days before this permit expires. If the permittee anticipates there will be no discharge after the expiration date of this
permit,the Division should be promptly notified so that it can terminate the permit in accordance with Part II.B.5.
12. Confidentiality
Any information relating to any secret process,method of manufacture or production,or sales or marketing data which has
been declared confidential by the pennittee,and which may be acquired,ascertained,or discovered,whether in any sampling
investigation,emergency investigation,or otherwise,shall not be publicly disclosed by any member,officer,or employee of
the Commission or the Division,but shall be kept confidential. Any person seeking to invoke the protection of this
Subsection(12)shall bear the burden of proving its applicability. This section shall never be interpreted as preventing full
disclosure of effluent data.
13. Fees
The pennittee is required to submit payment of an annual fee as set forth in the 2005 amendments to the Water Quality
Control Act. Section 25-8-502(1)(b),and the Colorado Discharge Permit System Regulations 5 CCR 1002-61, Section 61.15
as amended. Failure to submit the required fee when due and payable is a violation of the permit and will result in
enforcement action pursuant to Section 25-8-601 et. seq.,C.R.S.1973 as amended.
14. Duration of Permit
The duration of a permit shall be for a fixed term and shall not exceed five(5)years. Filing of a timely and complete
application shall cause the expired permit to continue in force to the effective date of the new permit. The permit's duration
may be extended only through administrative extensions and not through interim modifications.
15. Section 307 Toxics
If a toxic effluent standard or prohibition,including any applicable schedule of compliance specified, is established by
regulation pursuant to Section 307 of the Federal Act for a toxic pollutant which is present in the permittee's discharge and
such standard or prohibition is more stringent than any limitation upon such pollutant in the discharge permit,the Division
shall institute proceedings to modify or revoke and reissue the permit to conform to the toxic effluent standard or prohibition.
16. Effect of Permit Issuance
Permit,Part II
Page 31 of 34
Permit No. CO0048445
a. The issuance of a permit does not convey any property rights or any exclusive privilege.
b. The issuance of a permit does not authorize any injury to person or property or any invasion of personal rights,nor does
it authorize the infringement of federal, state,or local laws or regulations.
c. Except for any toxic effluent standard or prohibition imposed under Section 307 of the Federal act or any standard for
sewage sludge use or disposal under Section 405(d)of the Federal act,compliance with a permit during its term
constitutes compliance,for purposes of enforcement,with Sections 301,302,306,318,403,and 405(a)and(b)of the
Federal act. However, a permit may be modified,revoked and reissued,or terminated during its term for cause as set
forth in Section 61.8(8)of the Colorado Discharge Permit System Regulations.
d. Compliance with a permit condition which implements a particular standard for sewage sludge use or disposal shall be an
affirmative defense in any enforcement action brought for a violation of that standard for sewage sludge use or disposal.
Permit,Part III
Page 32 of 34
Permit No. CO0048445
PART III
CATEGORICAL INDUSTRIES
Aluminum Forming Meat Products
Asbestos Manufacturing Metal Finishing
Battery Manufacturing Metal Molding and Casting(Foundries)
Builders'Paper and Board Mills Mineral Mining and Processing
Canned&Preserved Fruits and Vegetables Processing Nonferrous Metals Manufacturing
Canned&Preserved Seafood Processing Nonferrous Metals Forming and Metal Powders
Carbon Black Manufacturing Oil and Gas Extraction
Cement Manufacturing Organic Chemicals,Plastics,and Synthetic Fibers
Coal Mining Ore Mining and Dressing
Coil Coating Paint Formulation
Copper Forming Paving and Roofing Materials(Tars and Asphalt)
Dairy Products Processing Pesticide Chemicals
Electrical and Electronic Components Petroleum Refining
Electroplating Pharmaceutical Manufacturing
Explosives Manufacturing Phosphate Manufacturing
Feedlots Photographic
Ferroalloy Manufacturing Plastics Molding and Forming
Fertilizer Manufacturing Porcelain Enameling
Glass Manufacturing Pulp,Paper,and Paperboard Manufacturing
Grain Mills Rubber Manufacturing
Gum and Wood Chemicals Manufacturing Soap and Detergent Manufacturing
Hospital Steam Electric Power Generating
Ink Formulation Sugar Processing
Inorganic Chemicals Manufacturing Textile Mills
Iron and Steel Manufacturing Timber Products Processing
Leather Tanning and Finishing
PRIORITY POLLUTANTS AND HAZARDOUS SUBSTANCES
ORGANIC TOXIC POLLUTANTS IN EACH OF FOUR FRACTIONS
IN ANALYSIS BY GAS CHROMATOGRAPHY/MASS SPECTROSCOPY(GC/MS)
Volatiles Base/Neutral Acid Compounds Pesticides
acrolein acenaphthene 2-chlorophenol aldrin
acrylonitrile acenaphthylene 2,4-dichlorophenol alpha-BHC
benzene anthracene 2,4,-dimethylphenol beta-BHC
bromoform benzidine 4,6-dinitro-o-cresol gamma-BBC
carbon tetrachloride benzo(a)anthracene 2,4-dinitrophenol delta-BHC
chlorobenzene benzo(a)pyrene 2-nitrophenol chlordane
chlorodibromomethane 3,4-benzofiuoranthene 4-nitrophenol 4,4'-DDT
chloroethane benzo(ghi)perylene p-chloro-m-cresol 4,4'-DDE
2-chloroethylvinyl ether benzo(k)fluoranthene pentachlorophenol 4,4'-DDD
chloroform bis(2-chloroethoxy)methane phenol dieldrin
dichlorobromomethane bis(2-chloroethyl)ether 2,4,6-trichlorophenol alpha-endosulfan
1,1-dichlorethane bis(2-chloroisopropyl)ether beta-endosulfan
1,2-dichlorethane bis(2-ethylhexyl)phthalate endosulfan sulfate
1,1-dichlorethylene 4-bromophenyl phenyl ether endrin
1,2-dichlorpropane butylbenzyl phthalate endrin aldehyde
1,3-dichlorpropylene 2-chloronaphthalene heptachlor
ethylbenzene 4-chlorophenyl phenyl ether heptachlor epoxide
methyl bromide chrysene PCB-1242
methyl chloride dibenzo(a,h)anthracene PCB-1254
methylene chloride 1,2-dichlorobenzene PCB-1221
Permit, Part III
Page 33 of 34
Permit No. CO0048445
PRIORITY POLLUTANTS AND HAZARDOUS SUBSTANCES
ORGANIC TOXIC POLLUTANTS IN EACH OF FOUR FRACTIONS
IN ANALYSIS BY GAS CHROMATOGRAPHY/MASS SPECTROSCOPY(GC/MS)
Volatiles Base/Neutral Acid Compounds Pesticides
1,1,2,2-tetrachloroethane 1,3-dichlorobenzene PCB-1232
tetrachloroethylene 1,4-dichlorobenzene PCB-1248
toluene 3,3-dichlorobenzidine PCB-1260
1,2-trans-dichloroethylene diethyl phthalate PCB-1016
1,1,1-trichloroethane dimethyl phthalate toxaphene
I,1,2-trichloroethane di-n-butyl phthalate
trichloroethylene 2,4-dinitrotoluene
vinyl chloride 2,6-dinitrotoluene
di-n-octyl phthalate
1,2-diphenylhydrazine(as azobenzene)
fluorene
fluoranthene
hexachlorobenzene
hexachlorobutadiene
hexachlorcyclopentadiene
hexachloroethane
indeno(1,2,3-cd)pyrene
isophorone
naphthalene
nitrobenzene
N-nitrosodimethylami ne
N-n i trosodi-n-propyl amine
N-nitrosodiphenylamine
amine
phenanthrene
pyrene
1,2,4-trichlorobenzene
OTHER TOXIC POLLUTANTS
(METALS AND CYANIDE)AND TOTAL PHENOLS
Antimony,Total
Arsenic,Total
Beryllium,Total
Cadmium,Total
Chromium,Total
Copper,Total
Lead,Total
Mercury,Total
Nickel,Total
Selenium,Total
Silver,Total
Thallium,Total
Zinc,Total
Cyanide,Total
Phenols,Total
Permit,Part III
Page 34 of 34
Permit No. CO0048445
TOXIC POLLUTANTS AND HAZARDOUS SUBSTANCES
REQUIRED TO BE IDENTIFIED BY EXISTING DISCHARGERS
IF EXPECTED TO BE PRESENT
Toxic Pollutants
Asbestos
Hazardous Substances
Acetaldehyde Isoprene
Ally!alcohol Isopropanolamine
Ally!chloride Keithane
Amyl acetate Kepone
Aniline Malathion
Benzonitrile Mercaptodimethur
Benzyl chloride Methoxychlor
Butyl acetate Methyl mercaptan
Butylamine Methyl methacrylate
Captan Methyl parathion
Carbary! Mexacarbate
Carbofuran Monoethyl amine
Carbon disulfide Monomethyl amine
Chlorpyrifos Naled
Coumaphos Napthenic acid
Cresol Nitrotoluene
Crotonaldehyde Parathion
Cyclohexane Phenolsulfanate
2,4-D(2,4-Dichlorophenoxy acetic acid) Phosgene
Diazinon Propargite
Dicamba Propylene oxide
Dichlobenil Pyrethrins
Dichlone Quinoline
2,2-Dichloropropionic acid Resorcinol
Dichlorvos Strontium
Diethyl amine Strychnine
Dimethy!amine Styrene
Dinilrobenzene TDE(Tetrachlorodiphenylethane)
Diquat 2,4,5-T(2,4,5-Trichlorophenoxy acetic acid)
Disulfoton 2,4,5-TP [2-(2,4,5-Trichlorophenoxy)propanoic acid]
Diuron Trichlorofan
Epichlorohydrin Triethylamine
Ethanolamine Trimethylamine
Ethion Uranium
Ethylene diamine Vandium
Ethylene dibromide Vinyl Acetate
Formaldehyde Xylene
Furfural Xylenol
Guthion Zirconium
Town of Erie WWTF Water Quality Assessment CO0048445
Water Quality Assessment
Boulder Creek
Town of Erie North Water Reclamation FacilityWWTF
Table of Contents
I. WATER QUALITY ASSESSMENT SUMMARY
II. INTRODUCTION 2
III. WATER QUALITY STANDARDS 4
Narrative Standards 4
Standards,for Organic Parameters and Radionuclides 4
Temperature 5
Segment Specific Numeric Standard 6
Table Value Standards and Hardness Calculations 7
Total Maximum Daily Loads and Regulation 93--Colorado's Section 303(d)List of Impaired Waters and
Monitoring and Evaluation List 9
IV. RECEIVING STREAM INFORMATION 9
Low Flow Analysis 9
Mixing Zones 10
Ambient Water Quality 11
V. FACILITY INFORMATION AND POLLUTANTS EVALUATED 12
Facility Information 12
Pollutants of Concern 12
VI. DETERMINATION OF WATER QUALITY BASED EFFLUENT LIMITATIONS(WQBELS) 13
Technical Information 13
Calculation of WQBELs 14
VII. ANTIDEGRADATION EVALUATION 18
Introduction to the Antidegradation Process 18
Significance Tests for Temporary Impacts and Dilution 19
New or Increased Impact and Non Impact Limitations(NILs) 19
Calculation of Loadings for New or Increased Impact Test 20
Determination of Baseline Water Quality(BWQ) 22
Bioaccumulative Significance Test 24
Significant Concentration Threshold 25
Determination of the Antidegradation Based Average Concentrations 25
Concentration Significance Tests 27
Antidegradation Based Effluent Limitations (ADBELs) 28
Alternatives Analysis 30
VIII. REFERENCES 30
I. Water Quality Assessment Summary
Table A-1 includes summary information related to this WQA. This summary table includes key
regulatory starting points used in development of the WQA such as: receiving stream information;
threatened and endangered species; 303(d) and 305(b) listings; low flow and facility flow
summaries; and a list of parameters evaluated.
Appendix A(WQA V 7.1) Page 1 of 31 Last Revised 10/15/10 -JN
Town of Erie WWTF Water Quality Assessment CO0048445
Table A-1
WQA Summary
Facility Information
Design
Design Flow Flow
Facility Name Permit Number (max 30-day ave, (max 30-
MGD) day ave,
CFS)
Fl. North Water Reclamation CO0048445 1.5 2.3
Facility
Receiving Stream Information
Receiving Stream Segment ID Designation Classification(s)
Name
Aquatic Life Warm 1 Recreation
S 1. Boulder Creek COSPBO 10 Undesignated Class E Agriculture
Water Supply
Low Flows (cfs)
Ratio of 30E3 to the
1E3 (1-day) 7E3 (7-day) 30E3 (30-day)
Design Flow (cfs)
6.4 6.4 12.2 5.3
Regulatory Information
T&E 303(d) Monitor and Existing Temporary Control
Species (Reg 93) Eval(Reg 93) TMDL Modification(s) Regulation
Yes,
ammonia, NH3 = TVS
No E.coli None 5/2003, (old), NH3 (ch)= None
updated in .06 (Type i) Exp
Report 264 12/31/2011
4/2008
Pollutants Evaluated
Fl: Ammonia, E. Coli, TRC, Metals, Temp, SAR, EC
II. Introduction
The water quality assessment (WQA) of Boulder Creek near the North Water Reclamation Facility
(WWTF), located in Weld County, is intended to determine the assimilative capacities available for
pollutants found to be of concern. This WQA describes how the water quality based effluent limits
(WQBELs) are developed. These parameters may or may not appear in the permit with limitations
or monitoring requirements, subject to other determinations such as reasonable potential analysis,
evaluation of federal effluent limitation guidelines, implementation of state-based technology based
Appendix A(wQA V 7.q Page 2 of 31 Last Revised 10/15/10 -JN
Town of Erie WWTF Water Quality Assessment CO0048445
limits, mixing zone analyses, 303(d) listings, threatened and endangered species listing, or other
requirements as discussed in the permit rationale. Figure A-1 contains a map of the study area
evaluated as part of this WQA.
FIGURE A-1
Erie North WRF Site Map
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oi.wula /74 a—.`n
g
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The North Water Reclamation Facility WWTF discharges to Boulder Creek, which is stream segment
COSPBO10. This means the South Platte River Basin, Boulder Creek Sub-basin, Stream Segment 10.
This segment is composed of the"Mainstem of Boulder Creek from the confluence with Coal Creek to
the Confluence with St.Vrain Creek.". Stream segment COSPBO10 is classified for Aquatic Life Warm
1, Recreation Class E, Water Supply and Agriculture.
Appendix A twQA V 7p Page 3 of 31 Last Revised 10/15/10 -JN
Town of Erie WWTF Water Quality Assessment CO0048445
Information used in this assessment includes data gathered from the North Water Reclamation Facility
WWTF, the Division, the Colorado Division of Water Resources (DWR), Riverwatch, the U.S.
Environmental Protection Agency(EPA)and the U.S.Geological Survey(USGS). The data used in the
assessment consist of the best information available at the time of preparation of this WQA analysis.
III. Water Quality Standards
Narrative Standards
Narrative Statewide Basic Standards have been developed in Section 31.11(1) of the regulations, and
apply to any pollutant of concern,even where there is no numeric standard for that pollutant. Waters of
the state shall be free from substances attributable to human-caused point source or nonpoint source
discharges in amounts, concentrations or combinations which:
for all surface waters except wetlands;
(i) can settle to form bottom deposits detrimental to the beneficial uses. Depositions are stream
bottom buildup of materials which include but are not limited to anaerobic sludge, mine slurry or
tailings, silt, or mud; or(ii) form floating debris, scum, or other surface materials sufficient to harm
existing beneficial uses; or(iii)produce color, odor, or other conditions in such a degree as to create
a nuisance or harm existing beneficial uses or impart any undesirable taste to significant edible
aquatic species or to the water; or(iv) are harmful to the beneficial uses or toxic to humans, animals,
plants, or aquatic life; or(v)produce a predominance of undesirable aquatic life; or (vi) cause a film
on the surface or produce a deposit on shorelines; and
for surface waters in wetlands;
(i)produce color, odor, changes in pH, or other conditions in such a degree as to create a nuisance or
harm water quality dependent functions or impart any undesirable taste to significant edible aquatic
species of the wetland; or(ii) are toxic to humans, animals, plants, or aquatic life of the wetland.
In order to protect the Basic Standards in waters of the state, effluent limitations and/or monitoring
requirements for any parameter of concern could be put in CDPS discharge permits.
Standards for Organic Parameters and Radionuclides
Radionuclides: Statewide Basic Standards have been developed in Section 31.11(2) and (3) of The
Basic Standards and Methodologies for Surface Water to protect the waters of the state from
radionuclides and organic chemicals.
In no case shall radioactive materials in surface waters be increased by any cause attributable to
municipal, industrial, or agricultural practices or discharges to as to exceed the following levels,
unless alternative site-specific standards have been adopted. Standards for radionuclides are shown
in Table A-2.
Appendix A(WQA v zp Page 4 of 31 Last Revised 10/15/10 -IN
Town of Erie WWTF Water Quality Assessment CO0048445
Table A-2
Radionuclide Standards
Parameter Picocuries per Liter
Americium 241* 0.15
Cesium 134 80
Plutonium 239, and 240* 0.15
Radium 226 and 228* 5
Strontium 90* 8
Thorium 230 and 232* 60
Tritium 20,000
*Radionuclide samples for these materials should be analyzed using unfiltered(total)samples.
These Human Health based standards are 30-day average values for both plutonium and
americium.
Organics: The organic pollutant standards contained in the Basic Standards for Organic Chemicals
Table are applicable to all surface waters of the state for the corresponding use classifications,unless
alternative site-specific standards have been adopted. These standards have been adopted as "interim
standards" and will remain in effect until alternative permanent standards are adopted by the
Commission. These interim standards shall not be considered final or permanent standards subject
to antibacksliding or downgrading restrictions. Although not reproduced in this WQA, the specific
standards for organic chemicals can be found in Regulation 31.11(3).
In order to protect the Basic Standards in waters of the state, effluent limitations and/or monitoring
requirements for radionuclides, organics, or any other parameter of concern could be put in CDPS
discharge permits.
The aquatic life standards for organics apply to all stream segments that are classified for aquatic life.
The water supply standards apply only to those segments that are classified for water supply. The water
+fish standards apply to those segments that have a Class 1 aquatic life and a water supply classification.
The fish ingestion standards apply to Class 1 aquatic life segments that do not have a water supply
designation. The water + fish and the fish ingestion standards may also apply to Class 2 aquatic life
segments, where the Water Quality Control Commission has made such determination.
Because the Boulder Crcck is classified for Aquatic Life Warm 1, with a water supply designation,
the water supply, water+ fish and aquatic life standards apply to this discharge.
Temperature
Temperature shall maintain a normal pattern of diurnal and seasonal fluctuations with no abrupt
changes and shall have no increase in temperature of a magnitude, rate, and duration deemed
deleterious to the resident aquatic life. This standard shall not be interpreted or applied in a manner
inconsistent with section 25-8-104, C.R.S.
Appendix A(WQA v zp Page 5 of 31 Last Revised 10/15/10 - JN
Town of Erie WWTF Water Quality Assessment CO0048445
Segment Specific Numeric Standards
Numeric standards are developed on a basin-specific basis and are adopted for particular stream
segments by the Water Quality Control Commission. The standards in Table A-3 have been assigned to
stream segment COSPBO10 in accordance with the Classifications and Numeric Standards for South
Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin.
Appendix A twQA v zq Page 6 of 31 Last Revised 10/15/10 - JN
Town of Erie WWTF Water Quality Assessment CO0048445
Table A-3
In-stream Standards for Stream Segment COSPBO10
Physical and Biological
Dissolved Oxygen(DO)=5 mg/I,minimum
pH=6.5-9 su
E.coli chronic= 126 colonies/100 ml
Temperature March-Nov=27.5°C M W AT and 28.6°C DM
Temperature Dec-Feb= 13.7°C MWAT AT and 14.3°C DM
Inorganic
Total Ammonia acute and chronic=TVS
Chlorine acute=0.019 mg/1
Chlorine chronic=0.011 mg/1
Free Cyanide acute=0.005 mg/I
Sulfide chronic=0.002 mg/1
Boron chronic=0.75 mg/I
Nitrite acute=0.05 mg/1
Nitrate acute= 10 mg/1
Chloride chronic=250 mg/I
Sulfate chronic=For WS,the greater of ambient water quality as ofJanuary 1,2000 or 250 mg/I
Metals
Dissolved Arsenic acute=340 µg/1
Total Recoverable Arsenic chronic=0.02 µg/1
Dissolved Cadmium acute and chronic=TVS
Total Recoverable Trivalent Chromium acute=50 µg/I
Dissolved Hexavalent Chromium acute and chronic=TVS
Dissolved Copper acute and chronic=TVS
Dissolved Iron chronic=For WS,the greater of ambient water quality as of January 1,2000,or 300 µg/1
Total Recoverable Iron chronic= 1000 µg/I
Dissolved Lead acute and chronic=TVS
Dissolved Manganese chronic=For WS,the greater of ambient water quality as of January 1,2000,or 50 µg/I
Dissolved Manganese acute and chronic=TVS
Dissolved Molybdenum chronic=135 µg/I
Total Mercury chronic=0.01 µg/1
Dissolved Nickel acute and chronic=TVS
Dissolved Selenium acute and chronic=TVS
Dissolved Silver acute and chronic=TVS
Dissolved Zinc acute and chronic=TVS
Table Value Standards and Hardness Calculations
Standards for metals are generally shown in the regulations as Table Value Standards(TVS),and these
often must be derived from equations that depend on the receiving stream hardness or species of fish
present; for ammonia, standards are discussed further in Section IV of this WQA. The Classification and
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Town of Erie WWTF TF Water Quality Assessment CO0048445
Numeric Standards documents for each basin include a specification for appropriate hardness values to
be used. Specifically, the regulations state that:
The hardness values used in calculating the appropriate metal standard should be based on
the lower 95%confidence limit of the mean hardness value at the periodic low flow criteria
as determined from a regression analysis of site-specific data. Where insufficient site-
specific data exists to define the mean hardness value at the periodic low flow criteria,
representative regional data shall be used to perform the regression analysis. Where a
regression analysis is not appropriate, a site-specific method should be used.
Daily flow data for Boulder Creek near the point of discharge of the North WRF was not available to
conduct a regression analysis based on the low flow. Therefore, the Division's alternative approach to
calculating hardness was used, which involves computing a mean hardness. The mean hardness was
computed to be 205 mg/1 based on sampling data from CDPH&E station 000033, (Boulder Creek at
Boulder-Weld County Line) located on Boulder Creek less than ''/a mile upstream from proposed Erie
North WRF discharge. There were eighty-four data points from this station available for the period of
record from January 2003 through July 2008.
Table A-4
TVS-Based Metals Water Quality Standards for CO0048445
Based on the Table Value Standards Contained in the Colorado Department of Public Health and
Environment Water Quality Control Commission Regulation 38
In-Stream Water TVS Formula:
Parameter
Quality Standard Hardness(mg/0 as CaCO3= 205
(0.9151(In(hardness))-3.1485)
Cadmium, Acute 5.1 µg/1 [1.136672-0.0418381n(hardness)]e
Dissolved (0.7998(In(hardness))-4.4451)
Chronic 0.73 µg/1 [1.101672-0.041838ln(hardness)]e
Hexavalent Acute 16 µg/1 Numeric standards provided,formula not applicable
Chromium,
Dissolved Chronic 11 µg/1 Numeric standards provided,formula not applicable
e(0.9422(In(hardness))-1.7408)
Copper, Acute 26 µg/1
Dissolved Chronic 17 µg/1 e(0.8545(1n(hardness))-1.7428)
Acute 140 µg/1 [1.46203-0.1457I21n(hardness)][e(1.273(In(hardness))-1.46)]
Lead, Dissolved (1.273(In(hardnoss))-4.705)]
Chronic 5.4 µg/1 [1.46203-0.1457121n(hardness)][e
Manganese, Acute 3792 µg/1 e(0333i(1n(hardness))+6.4676)
Dissolved Chronic 2095 µg/1 e(o.3331(In(hardness))+5.8743)
Nickel Acute 859 µg/I e(o.846pn namncss>)+2.zs3>
Dissolved Chronic 95 µg/1 e(0.8460np'ardness))+o.0554)
Selenium, Acute 18.4 µg/1 Numeric standards provided,formula not applicable
Dissolved Chronic 4.6 µg/1 Numeric standards provided,formula not applicable
Silver, Dissolved Acute 7 µg/1 1 e(1.72(ln(hardness))-6.52)
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Chronic 1.1 µg/1 e(I.72(In(hardness))-9.06)
Acute 264 µg/1 0.978et0.8525(1n(hardness))+1.0617)
Zinc, Dissolved (0.8525(In(hardness))+0.9109)
Chronic 229 µg/1 0.986 e
Total Maximum Daily Loads and Regulation 93 —Colorado's Section 303(d) List of Impaired
Waters and Monitoring and Evaluation List
This stream segment is on the 303(d) list of water quality impacted streams for E. coli.
For a receiving water placed on this list, the Restoration and Protection Unit is tasked with developing
the Total Maximum Daily Loads(TMDLs)and the Waste Load Allocation(WLAs)to be distributed to
the affected facilities. WLAs for E. coli have not yet been established. However, to facilitate the
completion of this WQA, the Town of Erie has agreed to accept chronic E. coli effluent limitations of
126 #/100 ml.
Additionally,the Division's Restoration and Protection Unit has completed a TMDL for ammonia and
the requirements of this TMDL would normally apply for this parameter. However, the TMDL was
completed prior to this facility being constructed and to facilitate completion of the previously written
PEL (PEL200175), the Town of Erie expressed willingness to accept stringent effluent limits for
ammonia. These effluent limits were listed in the PEL that was completed for the NWRF. Since the
writing of the PEL,the TMDL has been updated via Report 264(Lewis and McCutchen,4/2008)and the
wasteload allocations for total ammonia listed therein are those that will be used in the permit.
IV. Receiving Stream Information
Low Flow Analysis
Ideally,the low flow available to the Erie North WRF would be determined by a flow gage immediately
upstream of the facility. There are significant diversions and tributary additions between the facility and
either the closest upstream or downstream gauge with a daily flow record. In this case,the low flows are
synthesized from upstream gauges and diversion records. The low flow analysis was done by Lewis and
Saunders,and described in the document,Modeling and Analysis of Ammonia for Total Maximum Daily
Load in the St. Vrain Creek Drainage, including Boulder Creek and Coal Creek(referred to in the rest of
this analysis as the TMDL). hi their analysis,Lewis and Saunders did not calculate a 7E3 low-flow. For
the sake of consistency in this document,the 7E3 was set equal to the 1E3. Doing so will not affect the
outcome of any of the limits in the permit. As part of this TMDL,monthly acute and chronic flows were
developed for Boulder Creek above the confluence with Coal Creek and for Coal Creek. Since the
proposed discharge is less than a mile downstream from the confluence of Coal Creek with Boulder
Creek,the low flow is equal to the sum of the appropriate monthly flow for Coal Creek and the flow for
Boulder Creek above Coal Creek. There are no diversions in this reach. There is some accretion of
groundwater in this reach, but the amount is insignificant and was not added to the calculated flows
Based on the low flow procedure described above, the dilution low flows available to the North WRF
facility were calculated. The final dilution low flows are summarized in Table A-5.
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Table A-5
Dilution Low Flows for BoulderCreek for the
Town of Erie North WRF in CFS
Low Flow Annual Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec
(cfs)
1 E 6.4 64 65.8 63.4 15.8 6.4 21.7 9.9 17.2 9.3 10.2 36.5 56.4
Acute
7E3 6.4 64 65.8 63.4 15.8 6.4 21.7 9.9 17.2 9.3 10.2 36.5 56.4
30E3 12.2 69.4 69.9 66.9 26.5 14.4 32.3 12.2 37.9 22.4 31.9 49.2 60.4
Chronic
The TMDL represents a major effort by area dischargers and the Colorado Department of Public Health
to determine flows and impacts of multiple dischargers and diversions on water quality of Coal Creek
and Boulder Creek. This WQA analysis will utilize appropriate data from the TMDL process because it
is the best data set available and because it promotes consistency between permits within the basin.
The ratio of the low flow of Boulder Creek to the North Water Reclamation Facility WWTF design flow
is 5.3:1
Mixing Zones
The amount of the available assimilative capacity(dilution) that may be used by the permittee for the
purposes of calculating the WQBELs may be limited in a permitting action based upon a mixing zone
analysis or other factor. These other factors that may reduce the amount of assimilative capacity
available in a permit are: presence of other dischargers in the vicinity;the presence of a water diversion
downstream of the discharge(in the mixing zone);the need to provide a zone of passage for aquatic life;
the likelihood of bioaccumulation of toxins in fish or wildlife; habitat considerations such as fish
spawning or nursery areas; the presence of threatened and endangered species; potential for human
exposure through drinking water or recreation; the possibility that aquatic life will be attracted to the
effluent plume; the potential for adverse effects on groundwater; and the toxicity or persistence of the
substance discharged.
Unless a facility has performed a mixing zone study during the course of the previous permit, and a
decision has been made regarding the amount of the assimilative capacity that can be used by the facility,
the Division assumes that the full assimilative capacity can be allocated. Note that the review of mixing
study considerations, exemptions and perhaps performing a new mixing study(due to changes in low
flow, change in facility design flow, channel geomorphology or other reason) is evaluated in every
permit and permit renewal.
If a mixing zone study has been performed and a decision regarding the amount of available assimilative
capacity has been made, the Division may calculate the water quality based effluent limitations
(WQBELs) based on this available capacity. In addition, the amount of assimilative capacity may be
reduced by T&E implications.
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For this facility, 100% of the available assimilative capacity may be used as the facility has not had to
perform a mixing zone study, and the discharge is not to a T&E stream segment,and is not expected to
have an influence on any of the other factors listed above.
Ambient Water Quality
The Division evaluates ambient water quality based on a variety of statistical methods as prescribed in
Section 31.8(2)(a)(i) and 31.8(2)(b)(i)(B) of the Colorado Department of Public Health and
Environment Water Quality Control Commission Regulation No. 3/,and as outlined in the Division's
Policy for Characterizing Ambient Water Quality for Use in Determining Water Quality Standards Based
Effluent Limits (WQP-19). Ambient water quality is evaluated in this WQA analysis for use in
determining assimilative capacities and in completing antidegradation reviews for pollutants of concern,
where applicable.
Background water quality is based on data from the Colorado Water Quality Control Division Site
000033, Boulder Creek at Boulder-Weld County line. This site is immediately above the proposed
discharge point. This sample point is below Coal Creek, the last major tributary and above the
Goulding-Plumb and the Idaho Creek ditches, the last major diversions. There are more than 75 data
points for most of the regulated parameters. The period of record is January 2003 through July 2008.
Table A-4
Ambient Water Quality for Boulder Creek
Number Chronic
15th 50th 85th Maxima
Parameter of Stream Notes
Percentile Percentile Percentile Mean m
Samples Standard
Temp(°C) 86 6 13 23 14 29 NA
DO(mg/I) 77 8.6 11 13 4.1 126 5
pH(su) 81 8 8.6 8.9 8.5 9.4 6.5-9
E. coif(#/100 ml) 83 44 116 435 364 2419 126 1,3
TRC(mg/1) 0 0 0 0 0 0 0.011 2
Nitrate+Nitrite as N(mg/I) 28 1.3 3.9 5.9 3.6 8 NA
NH3 as N,Tot(mg/1) 84 0.1 0.1 2.3 0.75 5.8 TVS
As,Dis(µg/1) 71 0.95 1 3.6 2.3 9.6 340
Cd,Dis(µg/1) 84 0 0.45 0.5 0 2.3 0.73 2
Cr+3,TR(µg/1) 0 0 0 0 0 0 50 2
Cr+6,Dis(µg/1) 0 0 0 0 0 0 11 2
Cu,Dis(µg/l) 84 0 2.6 5.9 3 12 17 2
Fe,Dis(µg/1) 84 16 37 108 93 1158 300
Fe,TR(µg/1) 84 209 480 1777 1471 30570 1000
Pb,Dis(µg/l) 84 0 0.35 1.3 1.1 16 5.40 2
Mn,Dis(µg/1) 84 9.2 24 49 32 250 50
Se,Dis(µg/7) 84 0.38 1 4.8 2.3 42 4.6 3
Ag,Dis(µg/I) 84 0 0.14 0.14 0.3 2.5 1.1 2
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U,Dis(µg/I) 23 4 7 10 7.2 18 3310
Zn,Dis @g/I) 84 6 19 30 21 99 229
Sulfate(mg/I) 28 81 125 170 132 360 250
Hardness as CaCO3(mg/1) 84 140 212 254 205 450 NA
Note I: The calculated mean is the geometric mean.Note that for summarization purposes,the value of one was used where there was no detectable amount
because the geometric mean cannot be calculated using a value equal to zero.
Note 2: When sample results were below detection levels,the value of zero was used in accordance with the Division's standard approach for summarization and
averaging purposes.
Note 3: The ambient water quality exceeds the water quality standards for these parameters.
Note 4:For Cr and Hg,there were not available data to evaluate,but based on characteristics of similar streams in the watershed,background values arc
assumed to be zero.
V. Facility Information and Pollutants Evaluated
Facility Information
The North Water Reclamation Facility WWTF is located at North 1/4, Section 31, T2N, R68W in
Weld County. The current design capacity of the facility is 1.5 MGD (2.3 cfs). Wastewater
treatment is proposed to be accomplished using a mechanical wastewater treatment process. The
technical analyses that follow include assessments of the assimilative capacity based on this design
capacity.
The nearest major discharger on Boulder Creek was the Boulder 75th Street WWTP,approximately 8.9
miles upstream. (There are three major diversions, Ligget, Lower Boulder, and Boulder Weld County
ditches,and one major tributary,Coal Creek,between the Boulder 75th street discharge and the proposed
outfall location.) There are four major dischargers to Coal Creek: Superior(to Rock Creek a tributary to
Coal Creek), 14.5 miles above the confluence; Louisville, 11.2 miles above;Lafayette,7.3 miles above;
and Erie South, 2.3 miles above the confluence. There are several diversions in the segment of Coal
Creek from Superior to the confluence and some of the communities have implemented reuse programs.
Because of the location of the sample station 00033, the ambient water quality background
concentrations used in the mass-balance equation account for pollutants of concern contributed by
upstream sources, and thus it was not necessary to model upstream dischargers together witht the Erie
North WRF when determining the available assimilative capacities in Boulder Creek. Due to the
distance traveled and the changes in the characteristics of the receiving stream and confluence with the
larger St. Vrain Creek,modeling downstream facilities in conjunction with the Erie North WRF was not
considered necessary in this WQA. However, regional modeling by Lewis et al did include ammonia
modeling for other facilities and future modeling for metals may need to include the impact of other
facilities in the area. Distances between facilities made modeling TRC and E. coli together unnecessary.
Based on available information,there is no indication that non-point sources were a significant source of
pollutants of concern. Non-point sources were not considered in this assessment.
Pollutants of Concern
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Pollutants of concern may be determined by one or more of the following: facility type; effluent
characteristics and chemistry; effluent water quality data; receiving water quality; presence of federal
effluent limitation guidelines;or other information. Parameters evaluated in this WQA may or may not
appear in a permit with limitations or monitoring requirements,subject to other determinations such as a
reasonable potential analysis,mixing zone analyses,303(d)listings,threatened and endangered species
listings or other requirement as discussed in a permit rationale.
There are no site-specific in-stream water quality standards for BOD5 or CBOD5, TSS, percent
removal, and oil and grease for this receiving stream. Thus, assimilative capacities were not
determined for these parameters. The applicable limitations for these pollutants can be found in
Regulation No. 62 and will be applied in the permit for the WWTF.
The following parameters were identified by the Division as pollutants to be evaluated for this facility:
• Total Residual Chlorine
• E. coli
• Ammonia
• Temperature
• Metals and Cyanide
It is the Division's standard procedure to consider metals and cyanide as potential pollutants of concern
for all major domestic WWTFs.
In the Classifications and Numeric Standards for South Platte River Basin, Laramie River Basin,
Republican River Basin, Smokey Hill River Basin, COSPBO 10 is designated for water supply. However,
according to the Rationale for Classifications, Standards and Designations of the South Platte River
Basin, Laramie River Basin, Republican River Basin, Smokey Hill River Basin, there are no existing
public water supply uses for the receiving stream downstream from the North WRF discharge point to
the South Platte River. For this reason, nitrate is not evaluated as part of this analysis.
During assessment of the facility, nearby facilities, and receiving stream water quality, no additional
parameters were identified as pollutants of concern.
VI. Determination of Water Quality Based Effluent Limitations (WQBELs)
Technical Information
Note that the WQBELs developed in the following paragraphs, are calculations of what an effluent
limitation may be in a permit. The WQBELs for any given parameter, will be compared to other
potential limitations (federal Effluent Limitations Guidelines, State Effluent Limitations, or other
applicable limitation)and typically the more stringent limit is incorporated into a permit. If the WQBEL
is the more stringent limitation, incorporation into a permit is dependent upon a reasonable potential
analysis.
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In-stream background data and low flows evaluated in Sections II and III are used to determine the
assimilative capacity of Boulder Creek near the North Water Reclamation Facility WWTF for pollutants
of concern, and to calculate the WQBELs. For all parameters except ammonia, it is the Division's
approach to calculate the WQBELs using the lowest of the monthly low flows(referred to as the annual
low flow) as determined in the low flow analysis. For ammonia, it is the standard procedure of the
Division to determine monthly WQBELs using the monthly low flows,as the regulations allow the use
of seasonal flows.
The Division's standard analysis consists of steady-state,mass-balance calculations for most pollutants
and modeling for pollutants such as ammonia. The mass-balance equation is used by the Division to
calculate the WQBELs,and accounts for the upstream concentration of a pollutant at the existing quality,
critical low flow (minimal dilution), effluent flow and the water quality standard. The mass-balance
equation is expressed as:
M3Q3—MIQI
M2 =
Q2
Where,
=Upstream low flow (IE3 or 30E3)
Q2 = Average daily effluent flow (design capacity)
Q3 = Downstream flow (Qj + Q2)
M = In-stream background pollutant concentrations at the existing quality
Al, =Calculated WQBEL
M3 =Water Quality Standard, or other maximum allowable pollutant concentration
The upstream background pollutant concentrations used in the mass-balance equation will vary based on
the regulatory definition of existing ambient water quality. For most pollutants, existing quality is
determined to be the 85`h percentile. For metals in the total or total recoverable form,existing quality is
determined to be the 50th percentile. For pathogens such as fecal coliform and E. coli,existing quality is
determined to be the geometric mean.
For temperature,the highest 7-day mean(for the chronic standard)of daily average stream temperature,
over a seven consecutive day period will be used in calculations of the chronic temperature assimilative
capacity, where the daily average temperature should be calculated from a minimum of three
measurements spaced equally through the day. The highest 2-hour mean (for the acute standard) of
stream temperature will be used in calculations of the acute temperature assimilative capacity. The
highest 2-hour mean should be calculated from a minimum of 12 measurements spaced equally through
the day.
Calculation of WOBELs
Using the mass-balance equation provided in the beginning of Section VI, the acute and chronic low
flows set out in Section IV,ambient water quality as discussed in Section IV,and the in-stream standards
shown in Section III, the WQBELs for were calculated. The data used and the resulting WQBELs,M2,
are set forth in Table A-7a for the chronic WQBELs and A-7b for the acute WQBELs.
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When the ambient water quality exceeds the in-stream standard, the Division standard procedure is to
allocate the water quality standard to prevent further degradation of the receiving waters.
Chlorine: There are no point sources discharging total residual chlorine within one mile of the North
Water Reclamation Facility WWTF. Because chlorine is rapidly oxidized, in-stream levels of residual
chlorine are detected only for a short distance below a source. Ambient chlorine was therefore assumed
to be zero.
E. coli: There are no point sources discharging E. coli within one mile of the North Water Reclamation
Facility WWTF. Thus, WQBELs were evaluated separately. In the absence of E. coli ambient water
quality data, fecal coliform ambient data are used as a conservative estimate of E. coli existing quality.
Note that per Division practice,the limitations for E. coli must not exceed 2000 colonies per 100 ml(30-
day geometric mean). This 2000 colony limitation also applies to discharges to ditches.
Temperature: New TVS = WS -11°C is effective for this segment. The numeric levels for Warm
Stream Tier II(WS-11)°C are March—November chronic temperature standard of 27.5°C(MWAT)and
an acute standard of 28.6°C(DM). December through February the temperature standards are 13.7 °C
(MWAT)and 14.3 °C(DM). The MWAT is the maximum weekly average temperature,as determined
by a seven day rolling average,using at least 3 equally spaced temperature readings in a 24-hour day(at
least every 8 hours for a total of at least 21 data points). The daily maximum is defined as the maximum
2 hour average,with a minimum of 12 equally spaced measurements throughout the day.
A WQBEL for temperature can only be calculated if there is representative data,in the proper form,to
determine what the background Maximum Weekly Average Temperature and Daily Maximum ambient
temperatures are. As this data is not available at this time, the temperature limitation will be set at the
water quality standard and will be revisited in the future when representative temperature data becomes
available.
Table A-7a
Chronic WQBELs
Parameter I Q3(cis) Q2(cfs) Q3(cfs) M1 1113 M2
E. coli(#1100 ml) 12 2.3 14.3 364 126 126
TRC(mg/1) 12 2.3 14.3 0 0.011 0.068
As,TR(µg/1) 12 2.3 14.3 0 0.02 0.12
Cd,Dis(µg/I) 12 2.3 14.3 0.5 0.73 1.9
Cr+6,Dis(µg/I) 12 2.3 14.3 0 11 68
Cu,Dis(µg/I) 12 2.3 14.3 5.9 17 75
Fe,Dis(µg/1) 12 2.3 14.3 108 300 1302
Fe,TR(µg/1) 12 2.3 14.3 480 1000 3713
Pb,Dis(µg/1) 12 2.3 14.3 1.3 5.4 27
Mn,Dis(µg/I) 12 2.3 14.3 49 50 55
Hg,Tot(µg/1) 12 2.3 14.3 0 0.01 0.062
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Ni,Dis(µg/I) 12 2.3 14.3 0 95 591
Se,Dis(µg/I) 12 2.3 14.3 4.8 4.6 4.6
Ag,Dis(µg/I) 12 2.3 14.3 0.14 1.1 6.1
U,Dis(µg/I) 12 2.3 14.3 10 3310 20527
Zn,Dis(µg/I) 12 2.3 14.3 30 229 1267
Sulfate(mg/I) 12 2.3 14.3 170 250 667
Table A-7b
Acute WQBELs
Parameter Qr(cfs) Q2(cfs) 0(cfs) Ml M3 M2
TRC(mg/I) 6.4 2.3 8.7 0 0.019 0.072
As,Dis(µg/I) 6.4 2.3 8.7 3.6 340 1276
Cd,Dis(µg/I) 6.4 2.3 8.7 0.5 5.1 18
Cr,TR(µg/I) 6.4 2.3 8.7 0 50 189
Cr+6,(ug/I) 6.4 2.3 8.7 0 16 61
Cu,Dis(µg/I) 6.4 2.3 8.7 5.9 26 82
CN,Free(µg/1) 6.4 2.3 8.7 0 5 19
Pb,Dis(µg/1) 6.4 2.3 8.7 1.3 140 526
Mn,Dis(µg/1) 6.4 2.3 8.7 49 3792 14207
Ni,Dis(µg/I) 6.4 2.3 8.7 0 859 3249
Se,Dis(µg/I) 6.4 2.3 8.7 4.8 18.4 56
Ag,Dis(µg/I) 6.4 2.3 8.7 0.14 7 26
U,TR(µg/I) 6.4 2.3 8.7 0 30 113
U,Dis(µg/1) 6.4 2.3 8.7 10 5299 20016
Zn,Dis(µg/1) 6.4 2.3 8.7 30 264 915
Ammonia: The Ammonia Toxicity Model (AMMTOX) is a software program designed to project the
downstream effects of ammonia and the ammonia assimilative capacities available to each discharger
based on upstream water quality and effluent discharges. To develop data for the AMMTOX model,an
in-stream water quality study should be conducted of the upstream receiving water conditions,
particularly the pH and corresponding temperature, over a period of at least one year.
The current ammonia limits for the major discharger on Boulder Creek, Boulder 75th Street WRF, and
the dischargers on Coal Creek(which enters Boulder Creek just upstream of the proposed discharge of
the Erie North WRF), were set by the Boulder TMDL done by Dr. Lewis in 2003. Report 264 (2008),
which updated Report 164(2002)contains revised ammonia limitations for dischargers in the basin and
are the numbers that will be placed in the permit document and will be used until such a time as the
TMDL document is amended again. These limitations were based on ammonia modeling using the
existing Colorado ammonia standard and the AMMTOX software program.
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Effluent limits consistent with AMMTOX standards for ammonia are presented in Table A-8. Ammonia
limits presented in Table 31 of the TMDL document are low, particularly for dischargers on Coal Creek
and Boulder Creek, and in many cases, the difference between acute and chronic limits is small. There are
some opportunities for trading of assimilative capacity between dischargers, but allocations could be
altered only slightly for ammonia because the ammonia limits are so low as to offer little room for trades.
Ammonia limits for dischargers in the St. Vrain Creek basin are governed largely by pH, which can be
high throughout much of the basin during low flow conditions. During extended periods of low flow,
floods do not remove algal biomass from the stream substrate. High rates of photosynthesis can
dramatically increase the pH of a stream, and the effect of photosynthesis on pH is magnified in shallow
streams and during periods of low discharge. Although the drought of 2002-2003 does not appear to have
substantially affected DFLOW values for the St. Vrain basin, the drought may have indirectly affected
ammonia limits though its contribution to relatively high pH set points for some reaches in the St. Vrain
basin.
Compared with ammonia limits derived from earlier modeling, the limits proposed here are lower, and
acute limits are sometimes only a little higher than chronic limits. A primary cause for the overall
reduction in ammonia limits compared to previous analyses is the switch from CAM to AMMTOX
modeling. Chronic limits are related to the relationship between pH and the AMMTOX standard, and at
high pH, the difference between acute and chronic standards for AMMTOX modeling is small Thus, the
small differences between acute and chronic limits are an outcome of AMMTOX modeling in
combination with high pH values.
Proposed limits for nitrate-N exceed 20 mg/L in all months throughout the basin. Moderately high rates of
denitrification for some reaches, as determined through calibration of the model, provide assimilative
capacity for nitrate. At the present time, nitrate concentrations are of concern only at the mouth of St.
Vrain Creek and at points upstream of the dischargers considered here, so high nitrate concentrations in
the upper parts of the modeling area are consistent with concentrations below 10 mg/L at the mouth. If, in
the future, the drinking water standard for nitrate is imposed within the modeling area, effluent limits for
nitrate could be much lower than those proposed here.
Ammonia Limits
The modeling and an analysis of the historical performance of the Erie South WRF were the basis for
setting the preliminary effluent limitations for total ammonia at 2.5 mg/1 as a 30 day average and 8.0
mg/l as a daily maximum as they appeared in the Town's PEL,but because the TMDL and WLA process
have since been updated, the change was made to include more accurate, monthly limit values.
The AMMTOX model may be calibrated for a number of variables in addition to the data discussed
above. The values used for the other variables in the model are listed below:
• Stream velocity=0.3Qa.ad
• Default ammonia loss rate=6/day
• pH amplitude was assumed to be medium
• Default times for pH maximum, temperature maximum, and time of day of occurrence
• pH rebound was set at the default value of 0.2 su per mile
• Temperature rebound was set at the default value of 0.7 degrees C per mile.
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The results of the ammonia analyses for the North Water Reclamation Facility WWTF are presented in
Table A-8.
Table A-8
AMMTOX Results for Boulder Creek
at the North Water Reclamation Facility WWTF
Design of 1.5 MGD (2.3 cfs)
Month Total Ammonia Chronic(mg/1) Total Ammonia Acute(mg/1)
January 4.8 4.8
February 2.8* 2.8
March 3.1 3.3
April 2.7 2.9
May 2.3* 2.3
June 2.4 3.8
July 2.0* 2.0
August 1.9* 1.9
September 2.1* 2.1
October 3.2 4.4
November 4.8 9.0
December 5.0 7.8
*Acute is less than chronic;set acute to chronic
VII. Antidegradation Evaluation
As set out in The Basic Standards and Methodologies for Surface Water, Section 31.8(2)(b), an
antidcgradation analysis is required except in cases where the receiving water is designated as "Use
Protected." Note that"Use Protected" waters are waters "that the Commission has determined do not
warrant the special protection provided by the outstanding waters designation or the antidegradation
review process"as set out in Section 31.8(2)(b). The antidegradation section of the regulation became
effective in December 2000, and therefore antidegradation considerations are applicable to this WQA
analysis.
According to the Classifications and Numeric Standards for South Platte River Basin, Laramie River
Basin, Republican River Basin, Smoky Hill River Basin, stream segment COSPBO 10 is Undesignated.
Thus, an antidegradation review is required for this segment if new or increased impacts are found to
occur. Note that this is a change from the PEL,as the segment was classified as Use Protected when the
PEL was developed.
Introduction to the Antide2radation Process
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The antidegradation process conducted as part of this water quality assessment is designed to determine
if an antidegradation review is necessary and if necessary, to complete the required calculations to
determine the limits that can be selected as the antidegradation-based effluent limit (ADBEL), absent
further analyses that must be conducted by the facility.
As outlined in the Antidegradation Significance Determination for New or Increased Water Quality
Impacts, Procedural Guidance(AD Guidance),the first consideration of an antidegradation evaluation is
to determine if new or increased impacts are expected to occur. This is determined by a comparison of
the newly calculated WQBELs verses the existing permit limitations in place as of September 30,2000,
and is described in more detail in the analysis. Note that the AD Guidance refers to the permit
limitations as of September 30, 2000 as the existing limits.
If a new or increased impact is found to occur,then the next step of the antidegradation process is to go
through the significance determination tests. These tests include: 1)bioaccumulative toxic pollutant test;
2) temporary impacts test; 3) dilution test(100:1 dilution at low flow) and; 4) a concentration test.
As the determination of new or increased impacts, and the bioaccumulative and concentration
significance determination tests require more extensive calculations, the Division will begin the
antidegradation evaluation with the dilution and temporary impact significance determination tests.
These two significance tests may exempt a facility from further AD review without the additional
calculations.
Note that the antidegradation requirements outlined in The Basic Standards and Methodologies for
Surface Water specify that chronic numeric standards should be used in the antidegradation review;
however, where there is only an acute standard, the acute standard should be used. The appropriate
standards are used in the following antidegradation analysis.
Significance Tests for Temporary Impacts and Dilution
This is not a temporary discharge and therefore exclusion based on a temporary discharge cannot be
granted and the AD evaluation must continue.
The ratio of the chronic(30E3)low flow to the design flow is 5:1,and is less than the 100:1 significance
criteria. Therefore this facility is not exempt from an AD evaluation based on the dilution significance
determination test, and the AD evaluation must continue.
For the determination of a new or increased impact and for the remaining significance determination
tests,additional calculations are necessary. Therefore,at this point in the antidegradation evaluation,the
Division will go back to the new or increased impacts test. If there is a new or increased impact,the last
two significance tests will be evaluated.
New or Increased Impact and Non Impact Limitations (NILs)
To determine if there is a new or increased impact to the receiving water, a comparison of the new
WQBEL concentrations and loadings verses the concentrations and loadings as of September 30,2000,
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needs to occur. If either the new concentration or loading is greater than the September 2000
concentration or loading, then a new or increased impact is determined. If this is a new facility
(commencement of discharge after September 30, 2000) it is automatically considered a new or
increased impact.
Note that the AD Guidance document includes a step in the New or Increased Impact Test that calculates
the Non-Impact Limit(NIL). The permittee may choose to retain a NIL if certain conditions are met,and
therefore the AD evaluation for that parameter would be complete. As the NIL is typically greater than
the ADBAC, and is therefore the chosen limit, the Division will typically conclude the AD evaluation
after determining the NIL. Where the NILs are very stringent, or upon request of a permittee, the
Division will calculate both the NIL and the AD limitation so that the limitations can be compared and
the permittee can determine which of the two limits they would prefer, one which does not allow any
increased impact (NIL), or the other which allows an insignificant impact(AD limit).
The non impact limit(NIL)is defined as the limit which results in no increased water quality impact(no
increase in load or limit over the September 2000 load or limit). The NIL is calculated as the September
2000 loading,divided by the new design flow,and divided by a conversion factor of 8.34. If there is no
change in design flow, then the NIL is equal to the September 2000 permit limitation.
If the facility was in place,but did not have a limitation for a particular parameter in the September 2000
permit, the Division may substitute an implicit limitation. Consistent with the First Update to the AD
Guidance of April 2002, an implicit limit is determined based on the approach that specifies that the
implicit limit is the maximum concentration of the effluent from October 1998 to September 2000, if
such data is available. If this data is unavailable,the Division may substitute more recent representative
data, if appropriate, on a case by case basis. Note that if there is a change in design flow, the implicit
limit/loading is subject to recalculation based on the new design flow. For parameters that are
undisclosed by the permittee, and unknown to the Division to be present,an implicit limitation may not
be recognized.
This facility was not in place as a discharger as of September 30, 2000, and therefore this is
automatically considered a new or increased impact. The antidegradation review must continue to the
next two significance tests(bioaccumulative and concentration). To evaluate these significance tests the
antidegradation limitations need to be calculated.
Calculation of Loadings for New or Increased Impact Test
The equations for the loading calculations are given below. Note that the AD requirements outlined in
The Basic Standards and Methodologies for Surface Water specify that chronic numeric standards
should be used in the AD review; however, where there is only an acute standard, the acute standard
should be used. Thus,the chronic low flows will be used later in this AD evaluation for all parameters
with a chronic standard, and the acute low flows will be used for those parameters with only an acute
standard.
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Previous permit load= Mpermitted(mg/1) x Qpermitted(mgd) x 8.34
New WQBELs load= M2 (mg/1) x Q2(mgd) x 8.34
Where,
Mpermllted = September 2000 permit limit(or implicit limit) (mg/I)
Qpermttted =design flow as of September 2000 (mgd)
Q2 =current design flow(same as used in the WQBEL calculations)
M2 =new WQBEL concentration(mg/1)
8.34 =unit conversion factor
Table A-10 shows the results of these calculations and the determination of a new or increased
impact.
Table A-10
Determination of New or Increased Impacts
Sept 2000 New
Sept 2000 New or
Permit New WQBEL
Pollutant Permit NIL Increased
Load WQBEL Load Impact
Limit (lbs/day) (lbs/day)
E.coli(#/100 ml) NA NA NA 126 1576 Yes
TRC(mg/1) NA NA NA 0.068 0.85 Yes
NH3,Tot(mg/1) NA NA NA Various Various Yes
As,TR(µg/1) NA NA NA 0.12 0.0015 Yes
As,Dis(µg/1) NA NA NA 1276 16 Yes
Cd,Dis(µg/1) NA NA NA 1.9 0.024 Yes
Cr+3,TR(µg/1) NA NA NA 189 2.4 Yes
Cr+6,Dis(µg/I) NA NA NA 68 0.85 Yes
Cu,Dis(µg/1) NA NA NA 75 0.94 Yes
CN,Free(µg/1) NA NA NA 19 0.24 Yes
Fe,Dis(µg/I) NA NA NA 1302 16 Yes
Fe,TR(µg/1) NA NA NA 3713 46 Yes
Pb,Dis(µg/I) NA NA NA 27 0.34 Yes
Mn,Dis(µg/1) NA NA NA 55 0.69 Yes
Hg,Tot(µg/1) NA NA NA 0.062 0.00078 Yes
Ni,Dis(µg/1) NA NA NA 591 7.4 Yes
Se,Dis(µg/1) NA NA NA 4.6 0.058 Yes
Ag,Dis(µg/1) NA NA NA 6.1 0.076 Yes
U,Dis(µg/I) NA NA NA 20527 257 Yes
Zn,Dis(µg/1) NA NA NA 1267 1 16 Yes
Note that loading for E.coli cannot be calculated;but,for comparison purposes,the approach is sufficient.
Appendix A(WQA V 7.1) Page 21 of 31 Last Revised 10/15/10 - JN
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For all parameters there are new or increased impacts and in accordance with regulation,the permittee
has the option of choosing either the NIL's or ADBAC's. As this is a new facility,there are no NILs and
implicit limitations do not apply, therefore the ADBAC limitations must be calculated.
The final two significance determination tests(bioaccumulative and concentration)need to be applied,to
determine if AD limits are applicable. For the bioaccumulative test, the determination of the baseline
water quality (BWQ), the baseline water quality loading (BWQload), the threshold load(TL) and the
threshold load concentration(TL conc)needs to occur. For the concentration test,the BWQ,significant
concentration thresholds(SCT)and antidegradation based average concentrations(ADBACs)need to be
calculated. These calculations are explained in the following sections, and each significance
determination test will be performed as the necessary calculations are complete. The AD low flow may
also need to be calculated when determining the BWQ for an existing discharger(as of Sept 2000)when
upstream water quality data are used.
Determination of Baseline Water Quality (BWOI
The BWQ is the ambient condition of the water quality as of September 30,2000. The BWQ defines the
baseline low flow pollutant concentration, and for bioaccumulative toxic pollutants,the baseline load.
The BWQ is to take into account the influence of the discharger if the discharge was in place prior to
September 30, 2000. In such a case, data from a downstream location should be used to determine the
BWQ. If only upstream data is available, then a mass balance equation may be applied, using the
facilities effluent data to determine the BWQ. If the discharge was not present prior to September 30,
2000, then the influence of that discharge would not be taken into account in determining the BWQ. If
the BWQ has already been determined in a previous WQA AD evaluation, it may not need to be
recalculated as the BWQ is the water quality as of September 30,2000,and therefore should not change
unless additional data is obtained or the calculations were in error.
Consistent with current Division procedures, the BWQ concentrations for all pollutants of concern
should be established so that it can be used as part of an antidegradation review.
Because the North Water Reclamation Facility WWTF was not in existence as a discharger to Boulder
Creek as of September 30,2000,the influence of this discharger is not considered when determining the
BWQ. Data collected approximately 1 mile downstream from the North Water Reclamation Facility
WWTF,were available for a period of record of January 1995 through December 2000 for the following
pollutants: temperature,dissolved oxygen,pH,ammonia,TSS,hardness,Al(dis),Cu(dis),Cd(dis),As
(dis), Fe(dis),Fe(Tree),Pb(dis),Mn(dis),Hg(Tot). For some parameters there were no available data
points. Hexavalent chrome, trivalent chrome, nickel and cyanide were all assumed to be zero. Total
recoverable arsenic and uranium were set to the same value as that used for the dissolved fraction of
those parameters as there was data available for the dissolved forms.
The ambient water quality data are summarized in Table A-1 la. The BWQ concentrations based on
these data,represented by the 50`h percentile for total recoverable metals and total metals,the geometric
mean for coliforms,and the 85`h percentile for dissolved metals,and other pollutants,are summarized in
Table A-1 lb. There was no E.coli data available for the AD period. Therefore the Division used more
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recent data (Table A-4) to evaluate the baseline water quality. There was also no TRC data and no
dischargers within a mile of this facility, so instrcam TRC concentrations were assumed to be zero.
Table A-Ha
Ambient Water Quality Data Summary for AD Period
Number 15th 50th 85th
Parameter of Percentile Percentile Percentile Mean Location
Samples
Fecal Coliform(#/100 ml) 50 29 230 930 171 Downstream
E.colt(#/100 ml) 83 44 116 435 364 Downstream
TRC(mg/I) 0 0 0 0 0 Downstream
NH3 as N,Tot(mg/1) 34 0.0043 0.016 0.096 0.039 Downstream
-
As,Dis(µg/I) 35 0 0 1.9 0.52 Downstream
Cu,Dis(µg/1) 44 0 0 2.8 0.76 Downstream
Fe,Dis(µg/1) 18 19 55 73 51 Downstream
Fe,TR(µg/1) 44 155 515 898 574 Downstream
Pb,Dis(µg/1) 56 0 0 0 0.039 Downstream
Mn,Dis(µg/I) 56 12 27 43 29 Downstream
Hg,Tot(µg/1) 24 0 0 0 0 Downstream
Hg,Dis(µg/I) 11 0 0 0 0 Downstream
Se,Dis(µg/1) 37 1 2 2 1.7 Downstream
Ag,Dis(µg/1) 37 0 0 0.042 0.04 Downstream
U,Dis(µg/1) 18 2.4 4 5 3.6 Downstream
Zn,Dis(µg/I) 56 0 11 25 13 Downstream
Sulfate(mg/1) 56 58 86 100 80 Downstream
Hardness as CaCO3(mg/I) 56 123 170 195 161 Downstream
Table A-11b
BWQ Concentrations for Potential Pollutants of Concern
Based on Downstream Ambient Water Quality Concentrations
Pollutant Mef Qen-(efs) M„/, ails(efs) BWQ WQS
E.colt(#/100 ml) -- -- -- -- 364 126
TRC(mg/1) -- -- -- -- 0 0.011
As,TR(µg/1) -- -- -- -- 1.9 0.02
As,Dis(µg/1) -- -- -- -- 1.9 340
Cd,Dis(µg/1) -- -- -- -- 0 0.73
Cr+3,TR(µg/I) -- -- -- -- 0 50
Cr+6,Dis(µg/1) -- -- -- -- 0 11
Cu,Dis(µg/1) -- -- -- -- 2.8 17
CN,Free(µg/1) -- -- -- -- 0 5
Fe,Dis(µg/1) -- -- -- -- 73 300
Fe,TR(µg/1) -- -- -- -- 515 1000
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Pb, Dis(µg/I) -- -- -- -- 0 5.4
Mn,Dis(µg/I) -- -- -- -- 43 50
Hg,Tot(µg/1) -- -- -- -- 0 0.01
Ni,Dis(µg/1) -- -- -- -- 0 95
Se,Dis(µg/1) -- -- -- -- 2 4.6
Ag,Dis(µg/I) -- -- -- -- 0.042 1.1
U,TR(µg/1) -- -- -- -- 5 30
U,Dis(µg/I) -- -- -- -- 5 3310
Zn,Dis(µg/I) -- -- -- -- 25 229
Sulfate(mg/1) -- -- -- -- 100 250
Bioaccumulative Significance Test
For mercury, the bioaccumulative significance test can now be completed with some minor additional
calculations for the baseline water quality load(BWQload),the threshold load(TL),the new load based
on the WQBELs, and the threshold load concentration (TL cone). These terms are defined by the
following equations:
BWQ1oad=BWQ (from Table A-15) * AD low flow (chronic) * 8.34
Threshold Load (TL) = 0.1 * BWQload
Threshold Load Concentration (TL Conc) =TL-new design flow ± 8.34
WQBEL Load= new WQBEL(concentration) * new design flow * 8.34
The discharge is considered to be insignificant if the new load(WQBEL load) is less than the threshold
load (TL), or if the new WQBEL (concentration) is less than the TL Conc
Table A-12
Bioaccumulative Significance Test
Threshold Load Threshold
Parameter Concentration Load (TL) WQBEL Conc WQBEL Load
(TL Cone)
Mercury, Total 0 0 0.062 0.00078
For mercury, the WQBEL load is greater than the TL, and the WQBEL Cone is greater than the TL
Conc,and therefore additional consideration of the TL must occur. If the permittee accepts the TL,the
AD evaluation continues with the calculation of the SCT and ADBACs in the same manner as the other
non-bioaccumulative parameters, using the TL Conc in place of the WQBEL.
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If the TL is not acceptable, an AD Alternatives Analysis must be completed. For more information
regarding an Alternatives Analysis, refer to the Antidegradation Guidance and to Regulation 31.8
Significant Concentration Threshold
The SCT is defined as the BWQ plus 15%of the baseline available increment(BAI),and is calculated by
the following equation:
SCT= (0.15 x BA1) +BWQ
The BA1 is the concentration increment between the baseline water quality and the water quality
standard, expressed by the term (WQS —BWQ). Substituting this into the SCT equation results in:
SCT= 0.15 x (WQS-BWQ) + BWQ
Where,
WQS = Chronic standard or, in the absence of a chronic standard, the acute standard
BWQ =Value from Table A-11
The AMMTOX model is used to determine the SCTs for ammonia. Because the new ammonia standard
is based on a function of the pH and temperature of the receiving stream, the WQS changes moving
downstream from a discharge point. The BWQ and the SCT also change moving downstream. The
AMMTOX model calculates these values for every tenth of a mile, for up to 20 miles. Therefore, it is
impractical to show the SCTs for every part of the stream for all 12 months. These values are available
in the AMMTOX model, if requested.
Determination of the Antidegradation Based Average Concentrations
Antidegradation based average concentrations (ADBACs) are determined for all parameters except
ammonia, by using the mass-balance equation, and substituting the SCT in place of the water quality
standard, as shown in the following equation:
ADBAC = SCT x Q, —M, x Q,
Q2
Where,
=Upstream low flow (1E3 or 30E3 based on either the chronic or acute standard)
Q2 = Current design capacity of the facility
Q3 = Downstream flow (Qr + Q2)
MI = Current ambient water quality concentration (From Section III)
SCT = Significant concentration threshold
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The ADBACs were calculated using the SCTs, and are set forth in Table A-13a.
ADBACs for total ammonia are normally calculated by substituting the SCT in place of the chronic
standard in the AMMTOX model,which generates monthly ADBACs.In this case however,AMMTOX
returned values that were well above those values outlined in Report 264. As such,the ADBACs are the
less stringent between the two options and therefore the TMDL values shown in Table A-8 will be used
in the permit and the antidegradation evaluation for this parameter is complete.
Table A-13a
SCTs and ADBACs
Pollutant Qlefs) Q2(cfs) Q3(cfs) Mt SCT ADBAC
E. coli(#1100 ml) 12 2.3 14.3 364 126 126
TRC(mg/1) 12 2.3 14.3 0 0.0017 0.011
As,TR(µg/I) 12 2.3 14.3 0 0.02 0.12
As,Dis(µg/I) 6.4 2.3 8.7 3.6 53 190
Cd,Dis(µg/1) 12 2.3 14.3 0.5 0.11 0.11
Cr+3,TR(µg/1) 6.4 2.3 8.7 0 7.5 28
Cr+6,Dis(µg/I) 12 2.3 14.3 0 1.7 11
Cu,Dis(µg/1) 12 2.3 14.3 5.9 4.9 4.9
CN,Free(µg/I) 6.4 2.3 8.7 0 0.75 2.8
Fe,Dis(µg/I) 12 2.3 14.3 108 107 102
Fe,TR(µg/1) 12 2.3 14.3 480 588 1151
Pb,Dis(µg/1) 12 2.3 14.3 1.3 0.81 0.81
Mn,Dis(µg/I) 12 2.3 14.3 49 44 18
Hg,Tot(µg/1) 12 2.3 14.3 0 0.0015 0.0093
Ni,Dis(µg/1) 12 2.3 14.3 0 14 87
Se,Dis(µg/1) 12 2.3 14.3 4.8 2.4 2.4
Ag,Dis(µg/1) 12 2.3 14.3 0.14 0.2 0.51
U,TR(µg/I) 6.4 2.3 8.7 0 8.8 33
U,Dis(µg/1) 12 2.3 14.3 10 501 3063
Zn,Dis(µg/I) 12 2.3 14.3 30 56 192
Fluoride(mg/I) 6.4 2.3 8.7 0 2 7.6
Sulfate(mg/I) 12 2.3 14.3 170 123 123
Monthly
Pollutant
ADBAC
NH3,Total (mg/I)Jan 20.5
NH3,Total(mg/I)Feb 20.3
NH3,Total(mg/1)Mar 20.4
NH3,Total(mg/I)Apr 10.2
NH3,Total(mg/I)May 7.3
NH3,Total (mg/I)Jun 11.6
NH3,Total(mg/1)Jul 4.3
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NH3,Total(mg/1)Aug 11.6
NH3,Total(mg/I)Sep 9.1
NH3,Total(mg/I)Oct 11.4
NH3,Total(mg/I)Nov 17.2
NH3,Total(mg/1)Dec 18
Concentration Significance Tests
The concentration significance determination test considers the cumulative impact of the discharges over
the baseline condition. In order to be insignificant,the new or increased discharge may not increase the
actual instream concentration by more than 15%of the available increment over the baseline condition.
The insignificant level is the ADBAC calculated in Tables A-13a and A-13b above. If the new WQBEL
concentration(or potentially the TL Conc for bioaccumulatives)is greater than the ADBAC,an AD limit
would be applied. This comparison is shown in Tables A-14a and A-14b (for ammonia).
Table A-14a
Concentration Significance Test
Pollutant New WQBEL ADBAC Concentration Test Result
E.coli(#/100 ml) 126 126 Insignificant
TRC(mg/I) 0.068 0.011 Significant
As,TR(µg/I) 0.12 0.12 Insignificant
As,Dis(µg/1) 1276 190 Significant
Cd,Dis(µg/1) 1.9 0.11 Significant
Cr+3,TR(µg/I) 189 28 Significant
Cr+6,Dis(µg/I) 68 11 Significant
Cu,Dis(µg/I) 75 4.9 Significant
CN,Free(µg/I) 19 2.8 Significant
Fe,Dis(µg/1) 1302 102 Significant
Fe,TR(µg/I) 3713 1151 Significant
Pb,Dis(µg/1) 27 0.81 Significant
Mn,Dis(µg/1) 55 18 Significant
Hg,Tot(µg/I) 0.062 0.0093 Significant
Ni,Dis(µg/I) 591 87 Significant
Se,Dis(µg/1) 4.6 2.4 Significant
Ag,Dis(µg/1) 6.1 0.51 Significant
Ti,TR(µg/I) 113 33 Significant
U,Dis(µg/I) 20527 3063 Significant
Zn,Dis(µg/I) 1267 192 Significant
Fluoride(mg/I) 7.6 7.6 Insignificant
Sulfate(mg/I) 667 123 Significant
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Table A-14b
Concentration Significance Test for Ammonia
Pollutant TMDL value ADBAC Concentration Test Result
NH3,Total (mg/I)Jan 4.8 20.5 Insignificant
NH3,Total(mg/1)Feb 2.8 20.3 Insignificant
NH3,Total(mg/I)Mar 3.1 20.4. Insignificant
NH3,Total(mg/I)Apr 2.7 10.2 Insignificant
NH3,Total(mg/1)May 2.3 7.3 Insignificant
NH3,Total(mg/1)Jun 2.4 11.6 Insignificant
NH3,Total(mg/1)Jul 2 7.3 Insignificant
NH3,Total(mg/I)Aug 1.9 11.6 Insignificant
NI43,Total(mg/I)Sep 2.1 9.1 Insignificant
NH3,Total(mg/1)Oct 3.2 11.4 Insignificant
NH3,Total(mg/I)Nov 4.8 17.2 Insignificant
NH3,Total(mg/I)Dec 5 18 Insignificant
For E. coli, total recoverable arsenic,dissolved hexavalent chromium,free cyanide and dissolved nickle
the WQBELs are less than the ADBAC and therefore, the concentration test results in an insignificant
determination. The WQBELs are the final result of this WQA for these parameters and AD limitations
are not necessary.
For TRC, dissolved cadmium, dissolved copper,dissolved iron, total recoverable iron, dissolved lead,
dissolved manganese,total mercury,dissolved selenium,dissolved silver,dissolved uranium,dissolved
zinc and sulfate the WQBELs are greater than the ADBACs and therefore,the concentration test results
in a significance determination, and the antidegradation based effluent limitations (ADBELs) must be
determined.
Antidegradation Based Effluent Limitations (ADBELs)
The ADBEL is defined as the potential limitation resulting from the AD evaluation, and may be either
the ADBAC, the NIL, or may be based on the concentration associated with the threshold load
concentration (for the bioaccumulative toxic pollutants). ADBACs, NILs and TLs have already been
determined in the AD evaluation, and therefore to complete the evaluation, a final comparison of
limitations needs to be completed.
Note that ADBACs and N1Ls are not applicable when the new WQBEL concentration(and loading as
evaluated in the New and Increased Impacts Test) is less than the NIL concentration (and loading), or
when the new WQBEL is less than the ADBAC.
Where an ADBAC or NIL applies,the permittee has the final choice between the two limitations. A NIL
is applied as a 30-day average (and the acute WQBEL would also apply where applicable) while the
ADBAC would be applied as a 2 year rolling average concentration. For the purposes of this WQA,the
Division has made an attempt to determine whether the NIL or ADBAC will apply. The end results of
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this AD evaluation are in Table A-15, including any parameter that was previously exempted from
further AD evaluation, with the final potential limitation identified (NIL, WQBEL or ADBAC).
Table A-15
Final Selection of WQBELs, NILs, and ADBACs
Pollutant NIL New WQBEL ADBAC Chosen Limit
E. coli(#/100 ml) NA 126 NA WQBEL
TRC(mg/1) NA 0.068 0.011 ADBAC
NH3 as N,Tot(mg/1)Jan NA 4.8 NA WQBEL
NH3 as N,Tot as N(mg/1)Feb NA 2.8 NA WQBEL
NH3 as N,Tot(mg/1)Mar NA 3.1 NA WQBEL
NH3 as N,Tot(mg/I)Apr NA 2.7 NA WQBEL
NH3 as N,Tot(mg/1)May NA 2.3 NA WQBEL
NH3 as N,Tot(mg/I)Jun NA 2.4 NA WQBEL
NH3 as N,Tot(mg/1)Jul NA 2 NA WQBEL
NH3 as N,Tot(mg/1)Aug NA 1.9 NA WQBEL
NH3 as N,Tot(mg/1) Sep NA 2.1 NA WQBEL
NH3 as N,Tot(mg/1)Oct NA 3.2 NA WQBEL
NH3 as N,Tot(mg/1)Nov NA 4.8 NA WQBEL
NH3 as N,Tot(mg/1)Dec NA 5 NA WQBEL
As,TR(µg/1) NA 0.12 NA WQBEL
As,Dis(µg/1) NA 1276 190 ADBAC
Cd,Dis(µg/1) NA 1.9 0.11 ADBAC
Cr+3,TR(µg/I) NA 189 28 ADBAC
Cr+6,Dis(µg/I) NA 68 11 ADBAC
Cu,Dis(µg/I) NA 75 4.9 ADBAC
CN,Frce(µg/1) NA 19 2.8 ADBAC
Fe,Dis(µg/1) NA 1302 102 ADBAC
Fe,TR(µg/I) NA 3713 1151 ADBAC
Pb, Dis(µg/1) NA 27 0.81 ADBAC
Mn,Dis(µg/1) NA 55 18 ADBAC
Hg,Tot(µg/I) NA 0.062 0.0093 ADBAC
Ni,Dis(µg/I) NA 591 87 ADBAC
Se,Dis(µg/1) NA 4.6 2.4 ADBAC
Ag,Dis(µg/1) NA 6.1 0.51 I ADBAC
Appendix A twQA v 7.1) Page 29 of 31 Last Revised 10/15/10 - JN
Town of Erie WWTF Water Quality Assessment CO0048445
U,TR(µg/l) NA 113 33 ADBAC
U,Dis(µg/1) NA 20527 3063 ADBAC
Zn,Dis(µg/I) NA 1267 192 ADBAC
Sulfate(mg/1) NA 667 123 ADBAC
For the following parameters,TRC,dissolved arsenic,dissolved cadmium,dissolved copper,dissolved
iron, total recoverable iron, dissolved lead, dissolved manganese, total mercury, dissolved selenium,
dissolved silver,dissolved uranium,dissolved zinc and sulfate,the ADBACs have been established for
this facility. The ADBACs were selected as they are more stringent than the WQBELs and the NILs,or
perhaps due to the application as a two-year rolling average. However, the facility has the final choice
between the NILs and ADBACs,and if the ADBAC is preferred, the permit writer should be contacted.
Alternatives Analysis
If the permitter does not want to accept an effluent limitation that results in no increased impact(NIL)or
in insignificant degradation (ADBAC), the applicant may conduct an alternatives analysis (AA). The
AA examines alternatives that may result in no degradation or less degradation, and are economically,
environmentally,and technologically reasonable. If the proposed activity is determined to be important
economic or social development, a determination shall be made whether the degradation that would
result from such regulated activity is necessary to accommodate that development. The result of an AA
may be an alternate limitation between the ADBEL and the WQBEL, and therefore the ADBEL would
not being applied. This option can be further explored with the Division. See Regulation 31.8 (3)(d),
and the Antidegradation Guidance for more information regarding an alternatives analysis.
VIII. References
Regulations:
The Basic Standards and Methodologies for Surface Water, Regulation 31,Colorado Department Public
Health and Environment, Water Quality Control Commission, effective November 30, 2009.
Classifications and Numeric Standards for South Platte River Basin,Laramie River Basin, Republican
River Basin, Smoky Hill River Basin, Regulation No. 38, Colorado Department Public Health and
Environment, Water Quality Control Commission, effective 6/30/2010
Colorado's Section 303(d)List of Impaired Waters and Monitoring and Evaluation List,Regulation 93,
Colorado Department Public Health and Environment, Water Quality Control Commission, effective
April 30, 2010.
Policy and Guidance Documents:
Antidegradation Significance Determination for New or Increased Water Quality Impacts, Procedural
Guidance, Colorado Department Public Health and Environment, Water Quality Control Division,
December 2001.
Memorandum Re: First Update to (Antidegradation) Guidance Version 1.0, Colorado Department
Public Health and Environment, Water Quality Control Division, April 23, 2002.
Appendix A twQA v 7.0 Page 30 of 31 Last Revised 10/15/10 - IN
Town of Erie WWTF Water Quality Assessment CO0048445
Rationale for Classifications, Standards and Designations of Segments of the South Platte River,
Colorado Department Public Health and Environment, Water Quality Control Division, effective
October 29, 2002.
Policy Concerning Escherichia colt versus Fecal Conform, CDPHE, WQCD, July 20, 2005.
Colorado Mixing Zone Implementation Guidance, Colorado Department Public Health and
Environment, Water Quality Control Division, effective April 2002.
Policy for Conducting Assessments for Implementation of Temperature Standards in Discharge Permits,
Colorado Department Public Health and Environment, Water Quality Control Division Policy Number
WQP-23, effective July 3, 2008.
Implementing Narrative Standards in Discharge Permits for the Protection of Irrigated Crops, Colorado
Department Public Health and Environment, Water Quality Control Division Policy Number WQP-24,
effective March 10, 2008.
Policy for Characterizing Ambient Water Quality for Use in Determining Water Quality Standards
Based Effluent Limits, Colorado Department Public Health and Environment, Water Quality Control
Division Policy Number WQP-19, effective May 2002.
Appendix A twQA v 7.1) Page 31 of 31 Last Revised 10/15/10 - JN
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