HomeMy WebLinkAbout20123413.tiff MEMORANDUM
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T� TO: Chris Gathman, Planning Services DATE: September 10, 2012
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c ou N?zY FROM: Heidi Hansen, P.E., Public Works Department
SUBJECT: USR12-0057, Wells Ranch
A Use by Special Review permit for a crude oil central processing facility.
The Weld County Public Works Department has reviewed this proposal. This project falls under the Use
by Special Review Standard, Weld County Code, Chapter 23, Article II, Division 4, Section 23. Staff
comments made during this phase of the Use by Special Review process may not be all-inclusive, as
other issues may arise during the remaining application process.
COMMENTS:
CR 68 is a local gravel road and requires a 60-foot right-of-way at full build out. There is presently a 60-
foot right-of-way. This road is maintained by Weld County. Pursuant to the definition of SETBACK in the
Weld County Zoning (23-1-90), the required setback is measured from the future right-of-way line.
The application states that two people will visit the site daily after construction. The traffic associated with
this use after construction is minimal.
An improvements agreement is required for this site. Public Works will provide a draft of the agreement
after the Board of County Commissioners hearing for this project. An example Improvements Agreement
is available on the County Planning website under Application Assistance. Road maintenance after
construction will not be a part of this agreement. If the traffic were to increase in the future, road
maintenance may be required.
A new access has been proposed for this project and will be approved or denied by the County Traffic
Engineer. Please show the approved access points on the Plat and label them with the Access Permit
numbers (the permit number for the proposed new access will be provided if it is approved).
Contact the Permitting/Inspection agent for Weld County Public Works, at (970) 304-6496, ext. 3764 for a
Right-of-Way permit for any work that may be required in the right-of-way on County roads. A special
transport permit will be required for any oversized or overweight vehicles that may access the site and
may also be obtained through the same office.
In the event that 1 or more acres are disturbed during the construction and development of this site, the
applicant shall obtain a stormwater discharge permit from the Water Quality Control Division of the
Colorado Department of Public Health and Environment.
If more than 1 acre is to be disturbed, a grading permit will be required prior to the start of construction.
The grading permit application must contain: an erosion and sediment control plan, a grading plan,
installation details of all BMPs to be utilized, typical installation and maintenance notes for all BMPs to be
utilized, and a copy of the approved CDPHE stormwater permit.
The applicant provided a "Preliminary Drainage Report" dated August, 2012 and signed and stamped by
Steve E. Sciscione PE 46051 with Tetra Tech.
Please provide a drainage report that follows the USR-SPR Drainage Report Checklist and a complete
set of construction drawings that have been stamped, signed, and dated by a registered professional
engineer licensed in the State of Colorado.
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Comments from the review of the submitted drainage report must be addressed in the resubmitted
drainage report and on the construction drawings. The comments have been summarized and have been
returned to the applicant's engineer under separate cover.
This area IS NOT in a Special Flood Hazard Area (SFHA) as determined by the Federal Emergency
Management Agency (FEMA).
REQUIREMENTS:
1. Show on the Plat:
a. CR 68 is a local gravel road and requires a 60-foot right-of-way at full build out. The
applicant shall verify the existing 60 feet of right-of-way and the documents creating the
right-of-way and this information shall be noted on the plat. All setbacks shall be
measured from the edge of future right-of-way. If the right-of-way cannot be verified, it
shall be dedicated. This road is maintained by Weld County.
b. Show the approved access(es) on the Plat and label with the approved access permit
number (will be provided).
2. Before recording the Plat:
a. An improvements agreement including collateral for all on-site and off-site improvements
is required for this site.
b. Submit a drainage report that follows the USR-SPR Drainage Report Checklist and a
complete set of construction drawings that have been stamped, signed, and dated by a
registered professional engineer licensed in the State of Colorado.
3. Before Construction:
a. In the event that 1 or more acres are disturbed during the construction and development
of this site, the applicant shall obtain a stormwater discharge permit from the Water
Quality Control Division of the Colorado Department of Public Health and Environment.
b. If more than 1 acre is to be disturbed, a grading permit will be required prior to the start of
construction. The grading permit application must contain: an erosion and sediment
control plan, a grading plan, installation details of all BMPs to be utilized, typical
installation and maintenance notes for all BMPs to be utilized, and a copy of the
approved CDPHE stormwater permit.
4. Add the following notes to the plat:
a. Pursuant to Chapter 15, Articles I and II of the Weld County Code, if noxious weeds exist
on the property or become established as a result of the proposed development, the
applicant/landowner shall be responsible for controlling the noxious weeds.
b. Off-street parking spaces including the access drive shall be surfaced with gravel,
asphalt, recycled asphalt base, concrete or the equivalent and shall be graded to prevent
drainage problems.
c. The historical flow patterns and run-off amounts will be maintained on site in such a
manner that it will reasonably preserve the natural character of the area and prevent
property damage of the type generally attributed to run-off rate and velocity increases,
diversions, concentration and/or unplanned ponding of storm run-off.
d. The applicant must take into consideration storm water capture/quantity and provide
accordingly for best management practices.
e. Weld County is not responsible for the maintenance of onsite drainage related features.
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MEMORANDUM
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r . = TO: Chris Gathman, Planning Services DATE: September 20, 2012
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c o_u N-E z FROM: Heidi Hansen, P.E., Public Works Department
SUBJECT: USR12-0057, Wells Ranch
The comments below are in addition to our referral memo dated September 10, 2012. The
applicant added water recycling to the application and these comments are meant to address
that component. Staff comments made during this phase of the process may not be all-inclusive
as other issues may arise during the remaining application process.
COMMENTS:
The applicant will need to address how the water recycling component will affect the traffic narrative
provided with the original application. The original application has very minimal traffic after construction.
Please provide a narrative detailing the traffic expected for the water recycling component.
Please include the water recycling facilities in the revised Drainage Report for this site.
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_Additi onal_Commaits[1].docx
Case Name:Wells Ranch Gas Plant
Case Number: USR12-0057 Date: 9-5-12
Weld County Public Works
Use by Special Review (USR) and Site Plan Review (SPR)
Drainage Report Outline
The following checklist is to be utilized as guidance, and may not be all inclusive. Other concerns
not included in this checklist may arise during the review process.
NOTE: A HARDCOPY OF THE DRAINAGE REPORT AND CONSTRUCTION DRAWINGS MUST BE
SUBMITTED TO PUBLIC WORKS FOR REVIEW
Not
Comment Headings Included N/A
Included
All reports shall be typed on 8-1/2" x 11" paper and bound. Drawings
(24" x 36") shall be included. The drawings shall be bound within the
report or included within a pocket attached inside the back cover of the
report. The report shall be a stand-alone document and therefore all
important reference material, supporting documents, and calculations
shall be copied and included within the report appendix. The report shall X
include a cover letter presenting the drainage design for review and shall
be prepared or supervised by an engineer licensed in Colorado. Only
original documents sealed in ink will be accepted. The sealed report
shall contain a certification sheet as follows:
"I hereby certify that this report for the drainage design of(Insert Name of
Project)was prepared by me (or under my direct supervision) in
accordance with the provisions of the Weld County storm drainage
criteria for the owners thereof."
The Drainage Report is stamped, signed, and dated by a registered P.E.
licensed to practice in the State of Colorado. X
All submitted construction plan sheets are stamped, signed, and dated by X
a registered P.E. licensed to practice in the State of Colorado.
The following items at a minimum should be discussed in the Drainage Report narrative and should
be supported with maps and calculations in the Appendix. Include a copy of this checklist with the
Drainage Report submittal.
I. General Location and Description
A. Location
1. Township, Range, Section, ' -Section. X
2. Local streets within and adjacent to the development. X
3 Major open channels, lakes, streams, irrigation and other water resource X
facilities within and adjacent to proposed project site.
4 Names of surrounding developments including jurisdiction X
(municipalities).
B. Description of Property
1. Area in acres. X
2. Ground cover and soil types. X
3. Major open channels and property ownership. X
4. General project description. X
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Case Name:Wells Ranch Gas Plant
Case Number: USR12-0057 Date: 9-5-12
5 Irrigation facilities and facility ownership information within 200 ft. of
property.
6. Groundwater characteristics (where applicable). X
II. Drainage Basins and Sub-Basins
A. Major Basin Description
1. Reference to Weld County Master Drainage Plan(s)where applicable. X
2. Major basin drainage characteristics. X
3 Identification of all FEMA-defined 100-year floodplains and floodways )=LX
affecting the property.
On-site & offsite contours at minimum 2-ft vertical intervals are to be
included on the Drainage Report drawings.
B. Sub-Basin Description
1 Historic drainage patterns on the subject property and adjacent X
properties.
Off-site drainage flow patterns and impacts on the subject property X
2. (minimum 200 ft outside property boundary, or until no further off-site
contributing flow area is encountered).
III. Drainage Design Criteria
A. Development Criteria Reference and Constraints
Discussion of previous drainage studies (i.e. project master plans)for the X
1. subject property that influence or are influenced by the proposed
drainage design for the site.
Discussion of site constraints such as slopes, streets, utilities, existing X
2. structures, irrigation ditches, and the site plan impacts on the proposed
drainage plan.
B. Hydrological Criteria
1 Identify design rainfall amounts and source of design storm depth X
information, NOAA Atlas, UD&FCD maps, etc.
2 Identify design storm recurrence intervals. Reference the appropriate X
information in the Appendix.
Identify runoff calculation method(s)and any computer models. Include discuss
3 summaries of the routing and accumulation of flows at all identified
design points for minor and major storm runoff. Reference the results in
the Appendix.
4 Identify detention discharge and storage calculation methods and X
computer models. Reference the results in the Appendix.
5 Discuss of off-site flows will be routed around the proposed site or over X
the spillway for the 100-yr developed condition.
C. Hydraulic Criteria
1 Identify conveyance capacities from County references and any computer X
models.
Identify detention outlet type. Include a summary of the 100-year water X
2 surface elevation, spillway/overflow facility. Reference the appendix for
the calculations. Include summaries of the detention storage sizing and
provide a stage-storage table/curve identifying water quality storage, 100-
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Case Name:Wells Ranch Gas Plant
Case Number: USR12-0057 Date: 9-5-12
yr detention pond storage, and 1 ft of freeboard. Reference the
calculations in the Appendix.
3.
Identify water quality outlet configuration. Reference the calculations in X-
the Appendix. details
4.
Identify culverts including diameter, type, and slope. Reference the X -
calculations in the Appendix. details
5 Identify storm sewer inlets, manholes, etc. Reference the calculations in X
the Appendix.
6. Discussion of permanent erosion control features. X
Discussion and justification of criteria or calculation methods (for water X
7. quality, check dams, drop structures, rundowns, etc.) used that are not
presented in Weld County CODE.
IV. Drainage Facility Design
A. General Concept
1. Discussion of concept and typical on-site drainage patterns. X
2 Discussion of compliance with off-site runoff considerations and X
constraints.
3 Discussion of the content of all tables, charts,figures, or drawings in the X
report.
4 Discussion of anticipated hydraulic structures (channels, pipes, X
rundowns, etc.).
B. Specific Details
1 Discussion of maintenance access and aspects of the design. Include a X
maintenance plan.
With
2 Provide copies of CDPHE, CAFO, DBMS, or State Engineer's permit grading
applications where applicable.
permit
V. Conclusions
A. Compliance with the Weld County CODE
1. Statement of whether or not the design will meet Weld County Code. X
B. Drainage concept
1. Effectiveness of drainage design to control damage from storm runoff. X
Influence of proposed development on any applicable Weld County X
2. Master Drainage Plan recommendations.
Identification of and intent to obtain written approval of affected irrigation X
3 company or other property owner(s). Weld County may require that the
applicant provide evidence that offsite impacted jurisdictions have been
notified of the proposed plans.
4 Reference all criteria and technical resources utilized. X
The Appendices should include at a minimum the following information. The Drainage Report should
be a standalone document and needs to include copies of all pertinent references used in the
generation of the Drainage Report.
VI. Appendices
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Case Name:Wells Ranch Gas Plant
Case Number: USR12-0057 Date: 9-5-12
A. Hydrologic Computations
1 Vicinity Map showing location of the site in relation to surrounding area. X
Show the approximate boundaries of the site.
2 FIRMette showing location of the site in relation to the FEMA mapped X
floodplains/floodways. Show the approximate boundaries of the site.
3 Soil Survey Information/Map showing soil types and soil hydrologic X
groups for the project site.
4 Rainfall Maps with the project location identified. Maps can be from X
UDFCD or NOAA as applicable.
5. Land use assumptions regarding adjacent properties. X
6 Initial and major storm runoff computations at specific design points. (5- X
yr, 10-yr, and 100-yr)
7. Historic and fully developed runoff computations at specific design points. X
8. Computer model input and output. Include model files and/or X
spreadsheets on a CD-ROM to be attached to the Drainage Report.
B. Hydraulic Computations
Culvert sizing. Provide computations showing slope, pipe size, material, X-
1. invert elevations, 100-year energy grade line (EGL100), and hydraulic details
profile.
2. Storm inlet sizing. X
3 Swale or channel sizing. The calculations need to show stability X
calculations for unvegetated and vegetated conditions. details
4 Riprap or other revetment design. The calculations need to include X
design for bedding and geo-fabric.
5 Pond area/volume capacity and outlet sizing. Show calculations for the X
100-year water surface elevations and overflow facilities. details
6. Orifice plate, spillway, and pond outlet sizing. X
details
7. Include computations for permanent erosion control features. X
details
8. Any computer model input and output. Include model files and/or X
spreadsheets on a CD-ROM to be attached to the Drainage Report.
C. 24 x 36 Maps
Historic Drainage Basin Map. Show drainage basin boundaries (on-site X
1. and off-site), 2 ft on-site and off-site drainage boundaries, design points,
historic flow path,flow path length, and flow path slope.
Fully Developed Drainage Basin Map. Show drainage basin boundaries X
(on-site and off-site), 2 ft on-site and off-site drainage boundaries, design
2 points, developed flow path, flow path length, and flow path slope. Show
drainage easement including metes and bounds description around all
drainage related features. Show any other drainage easements that may
exist on the project site.
Construction Drawings showing location, sizing, and details for all storm X
3. sewers, open channels, culverts, cross-pans, and other appurtenances.
Include cross sections of swales and open channels.
Construction Drawings showing location of detention facilities and outlet X
4. works. Include the 100-year water surface elevations, overflow facilities,
and labels for pond volume and discharge.
Grading Plan showing existing and proposed contours. Identify the X
5. lowest opening elevation of buildings showing that they are above the
100-year water surface elevations of channels, swales, streets, ponds, or
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Case Name:Wells Ranch Gas Plant
Case Number: USR12-0057 Date: 9-5-12
other drainage facilities.
Erosion and Sediment Control Plan showing all BMPs to be utilized on- X
6. site. Include typical installation details, installation notes, and
maintenance notes for all BMPs to be utilized on the project site.
7 Detail sheets for pond outlet, orifice plate,trash rack, spillway X
configuration, riprap, culverts, channels, etc.
All culverts are to be identified and profiled in the Construction Drawings X
8. with slope, pipe size, material, invert elevations, 100-year energy grade
line (EGL100), and hydraulic profile.
9 On all Construction Drawings show the location of all existing and X
proposed utilities and identify the utility as existing or proposed.
10. The elevations of manhole and inlet inverts are identified and profiled. X
11. Miscellaneous hydraulic structures/features are shown on the X
Construction Drawings.
1. Appendix C-3 and C-4 —The flow length calculations do not follow the accepted
methodology for determining time of concentration. The overland flow length cannot
exceed more the 500 feet before moving into channel or swale flow. Please review and
revise the calculations as necessary to properly account for the flow length. Changes in
the flow length will affect the time of concentration and the discharge for each basin.
Please show the various flow lengths on the drainage basin maps that are included with
the drainage report.
2. Appendix D-1 —The calculations for the driveway culvert show that the velocity exiting
the culvert will be erosive.
3. Appendix D-2 —The site ditch design appears to account for the only the capacity of the
ditch. The calculations also must show that the ditch is stable. Please utilize Table MD-
2 on page 27 of the Drainage Criteria, Volume 1 to show that the ditch will not erode
when stormwater runoff is flowing in it.
4. Appendix D-3 — It is not clear where the allowable unit release rate is coming from. The
release rates used for detention ponds A-1, A-2 and B do not appear to be related to the
5-year historic release rate. Please review and revise the calculations as necessary.
5. Please provide calculations for the orifice plates, spillway, riprap sizing, riprap rap
bedding, and any erosion protection that is needed.
6. Please ensure that all maps and drawings that are included in the drainage report are
stamped, signed, and dated by a registered professional engineer that is licensed in the
State of Colorado.
7. Please provide a complete set of construction drawings. The construction drawings
must include an erosion and sediment control plan, a grading plan, typical BMP
installation details and notes including a seed mix to be utilized in areas to be reseeded,
detail sheets for the spillways, culverts, riprap, riprap bedding, trash racks, outlets, pipes,
ditches, etc. It is important to ensure that the spillways and any flared end sections are
protected with cutoff walls to protect them against erosion.
8. Please include construction drawings for the future detention pond B that is being
proposed and show the planned grading for the pond.
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