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Home My WebLink About20120129 r. RECEIVED &1UAëFCI Weld C(oouu�nttyF Planning Department mnmonal RAWK[SI Wa1T a1[[anM1 7430 E. Caley Avenue, Ste 310 Centennial, CO Mfi I' fioQne(Uc 771-9150 - Fax(303) 771-8776 December 30, 2011 113320 Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, Colorado 80246-1530 Mr. Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Colorado 80631 RE: North Weld Landfill, Ault,Colorado Second Half 2011 Groundwater Monitoring Report Dear Mr. Henderson and Mr. Swain: On behalf of Waste Management Disposal Services of Colorado, Inc., AquAeTer, Inc. submits the second half 2011 groundwater detection monitoring results for the North Weld Landfill (NWLF) in Ault, Colorado. Regular semi-annual detection groundwater monitoring was completed in September 2011. Enclosed is one copy of the report for CDPHE, one copy of the report for WCDPHE, and an electronic file containing laboratory analytical data for CDPHE. There were no volatile organic compound detections and no statistical exceedances during the second half 2011 event, and NWLF remains in detection monitoring in accordance with 6 CCR 1007-2, Part 1 — Regulations Pertaining to Solid Waste Sites and Facilities (revised March 30, 2011). In anticipation of including shallow well MW-9 in the groundwater monitoring system prior to landfilling in the vicinity as early as 2015, one event of background monitoring at this well was conducted in the 2H11. The monitoring results for well MW- 9 are included in this report. e,6rvwl,u.no cu utivy 2012-0129 /-II-Zol :- PL or1 r7 '7 Mr. Jerry Henderson and Mr. Troy Swain 113320 December 30,2011 Paget If you have any questions pertaining to the groundwater detection monitoring program at NWLF, please contact Mr. Bill Hedberg at (970) 686-2800 or Mr. Tom Schweitzer at(303) 914-1445. Sincerely, AquAeTer, Inc. l1 (1 ( 2 C Terra Plute, E.I. Cathryn Stewart, P.G. Project Engineer Project Manager cc: Ms. Kim Ogle, WCDPS, w/o enc. Mr. Louis Bull, Waste Management, w/enc. Mr. Bill Hedberg, Waste Management, w/enc. Mr. Brad Pollock, Waste Management, w/o enc. Mr. Tom Schweitzer, Waste Management, w/enc. ins'2- 895 'W RECEIVED 2400 West Union Avenue Englewood, CO 80110 WASTE MANAGEMENT JAN 12 9019 303-914-1445(Phone) 866-442-0285(Fax) GREELEY OFFICE Weld County rianning Department January 9, 2012 Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, CO 80246-1530 Mr. Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, CO 80631 SUBJECT: NORTH WELD LANDFILL FOURTH QUARTER 2011 GAS MONITORING REPORT Dear Mr. Henderson and Mr. Swain: Enclosed for your information is the Fourth Quarter 2011 Gas Monitoring Report for North Weld Landfill (NWLF). The report dated December 22, 2011 was prepared by AquAeTer and documents their field monitoring activities conducted on December 13, 2011. The gas monitoring report contains monitoring results from the Phase 1 and 2 perimeter soil gas probes GP-06, GP-07, GP-10 through GP-20, structure probes GP-01 and GP-02, inside the shop and office, and confined spaces in the vicinity of the western boundary of the site. A map showing the gas probe locations, the scale house and maintenance shop is included as Figure 1. Section 2.3.1 of the Regulations Pertaining to Solid Waste Sites and Facilities, 6 CCR 1007-2, Part 1 (Regulations) requires that the concentration of explosive gases shall not exceed (A) 25% of the lower explosive limit (LEL) (1% by volume in air for methane) within facility structures, and (B) the LEL (5% by volume in air for methane- i.e., percent methane)at the facility boundary. During this monitoring event, methane was detected in perimeter probes GP-06 at a concentration of 5.7%, GP-10 at a concentration of 15.7% and structure probe GP-01 at a concentration of 14.0%. Combustible gas above regulatory limits was not detected in any of the other probes, shop, office or confined spaces. The facility currently operates under an approved gas remediation plan prepared in response to elevated gas concentrations in structure probe GP-01 and perimeter probes GP-10 and GP-11. The plan includes monthly monitoring of these probes and utility corridor access points along WCR 25. Included in Attachment 1 are the October and November 2011 monthly reports. A summary of the test results for these monthly events is provided in the following table. O4mliWull c LRv/a—O/.24/ i a3 �oi� PL O7'7'1 Letter Jerry Henderson and Troy Swain January 9, 2011 Page 2 CH4 Concentration Monitoring Probe October 2011 November 2011 GP-01 14.4 12.1 GP-10 7.5 0.6 GP-11 0.0 0.0 Methane was not observed in the utility corridor access points or facility structures during the monthly monitoring. The approved remediation plan also included the installation of passive gas vents in waste along the westem limit of the disposal area. As stated in the plan, the passive vents, which were installed in December 2009, may require one or more years to show consistent reduction in methane concentrations at perimeter probes GP-10 and GP-11 and structure probe GP-01. Until methane concentrations are below the regulatory threshold for three consecutive monthly events, monthly monitoring will continue to be performed. GP-06 will be added to the monthly monitoring program. This event represents the first observed methane concentration above regulatory limits in GP-06, which, similar to GP-01 and GP-10, is located in the facility's southwest quadrant. The closest adjoining property is the State Highway 14 right-of-way approximately 150 feet south of GP-06. The property to the south of the highway is agricultural land with active oil and gas production activities. Continuous methane monitors are in operation within the facility maintenance building, office and gatehouse and no methane detections have been observed. In November 2011, we informed CDPHE and WCDPHE of our plans to install additional passive gas vents in the southwest corner of the disposal area to establish an inward gradient for landfill gas in order to attenuate gas concentrations in the gas probes. Due to scheduling conflicts with the drill rig and crew, we were unable to install the additional vents last year. We are in the process of determining driller availability for 2012. We are also re-evaluating the layout of the proposed additional vents and considering other options to address gas migration in the southwest corner of the site. We anticipate providing CDPHE and WCDPHE with our recommended approach within the next 30-45 days. Please contact me at(303) 914-1445 should you have questions about this report. Sincerely, On behalf of North Weld Landfill Tom Schweitzer Engineering Manager cc: Kim Ogle, WCDPS, w/o enc. Bill Hedberg, NWLF RECEIVED2400 West Union Avenue Englewood, CO 80110 FEB 1 0 2012 303-914-1445(Phone) WASTE MANAGEMENTg Weld County rIammig Department 303-914-9937(Fax) GREELEY OFFICE February 7, 2012 Ms. Dana Podell Air Pollution Control Division (APCD-SS-B1) Colorado Department of Public Health and Environment 4300 Cherry Creek Drive South Denver, CO 80246-1530 Certified Mail 7003 3110 0005 2391 8649 RE: ANNUAL NMOC EMISSION RATE REPORT NORTH WELD LANDFILL AIRS ID: 123/209/1 Dear Ms. Podell, As required under the State Emissions Guideline Program for municipal solid waste landfills, attached is the 2011 Annual NMOC Emission Rate Report for North Weld Landfill (NWLF) located at 40,000 County Road 25, Ault, Colorado. 40 CFR 60.754(a) provides two equations for determining NMOC emission rates. One equation is for sites with unknown (estimated) solid waste acceptance rates, which is what the site heretofore has used for calculating the emission rate at the facility. The other equation is for sites with known waste acceptance rates (e.g., tonnage-based sites). For sites that include time periods with both known and estimated acceptance rates, the Regulation indicates both equations should be used. The enclosed Emission Rate Report reflects this change resulting from the installation of scales at the site on February 1, 2010. Page 1 of the report provides the emission rate calculation based on the estimated waste volumes (for waste received prior to February 1, 2010), and Page 2 of the Report provides the emission rate calculation for tons received at the site (for waste received after February 1, 2010). As we agreed in 2011, this report reflects the revised submittal schedule, which is to occur based on the calendar year (i.e. from January 1 through December 31 of each year), to be submitted to CDPHE by February 15 of each year. Should you have any questions regarding the information contained in this report, please contact me at 303-914-1445. Sincerely, Toni chweitzer Engineering Manager Enclosure cc: Troy Swain, WCDPHE Kim Ogle, WCDPS Jerry Henderson, CDPHE Bill Hedberg, NWLF Bruce Clabaugh, Waste Management &Wiwil,co i,) 20/a—O/a9 /3LD777 2010 Tier 2 NMOC Emission Rate Report North Weld Landfill Prior to scale installation on February 1,2010,volume of waste accepted was estimated based on container size of incoming waste. Therefore,because the actual year-to-year solid waste acceptance rate is estimated, the equation found in 40 CFR 60.754(a)(ii)was used to determine NMOC emission rates for this time period. MNMoc=2LoR(e ke-e kt)(CNMoc)(3.6 x 10-9) NMOC Emission Rate for Years with Estimated Waste Acceptance Rates MNMoc = Mass emission rate of NMOC, Mg/yr Lo = Refuse methane generation potential,m3/Mg = 170.00 2 R = Average annual acceptance rate,Mg/yr = 122,534.25 t k = Methane generation rate constant, 1/yr = 0.02' c = Years since closure,yrs = 0.00 (c=0 for active and/or new landfills) = Age of landfill,yrs = 19.91 CNMOG = Concentration of NMOC,ppm as hexane = 153.00 2 Conversion factor = 3.6 x 10'4 MNMoc=2(Lo)(R)(ei"°ef-ei"°'))(Cnmoc)(3.6 x 10-9) = 7.54 Mglyr 1 Information used to determine annual average acceptance rate The average annual acceptance rate(R)is determined by taking the total waste received between the approximate opening date of February 3, 1992 and January 31,2010 divided by the number of years for this period. Total tons received as of 01/31/10 4,584,717.63 Total tons converted to Mg5 4,159,228.55 Percent inert(including soil) 0.47 Total Mg less inert waste6 2,204,391.13 Age of site as of 01/31/10 17.99 Annual average acceptance rate(Mg/yr) 122,534.25 2 For regulatory purposes,the EPA default values for Lo and CNMOC must be used to calculate Tier 1 NMOC emission rates unless actual values have been obtained during Tier 2 sampling. NWLF conducted Tier 2 site specific sampling for CNMOC in 2008(using Method 25C)with a resulting concentration of 153 ppmV as hexane. 6 For landfills in areas with a thirty year annual average precipitation of less than 25 inches,a k value of 0.02 is to be used. Annual precipitation in the area of North Weld Landfill is about 13 inches,therefore a k value of 0.02 has been used in the NMOC emission rate calculation. Gas generation from waste accepted after January 31,2010 is calculated with"Known Waste Acceptance Rate" NSPS equation. 5 Conversion Used:Tons to Mg-Divide tons by 1.1023 6 Inert material includes inert wastes that are disposed in the landfill as well as intermediate and final cover soil used as part of routine landfill cell development. NOTE. These calculations are made for N5P5 purposes only. EPA has specifically stated as follows:"It is recommended that these default values not be used for estimating landfill emissions for purposes other than NSPS and EG" (61 FR 9905,9912,march 12,1996). Consequently,these emission calculations grossly overestimate actual and potential emissions and reviewers of this document are specifically cautioned against improper and Irtesonsible uses of these calculations. Page 1 of 2 NWLF NMOC Tier 2 Report 2011.xIs 2011 Tier 2 NMOC Emission Rate Report North Weld Landfill 40 CFR 60.754(a)provides two equations for determining NMOC emission rates;one for sites with known solid waste acceptance rates and another for sites with unknown(i.e.estimated)waste acceptance rates. For sites that include time periods with both known and unknown acceptance rates,the Regulation indicates that both equations should be used. North Weld Landfill is such a facility. Accordingly,this Emission Rate Report applies both equations for calculating the facility's 2010 Tier 2 NMOC emission rate. NMOC Emission Rate Calculations for Years with Known Waste Acceptance Rates The site installed scales on February 1,2010. Therefore,the equation found in 40 CFR 60.754(a)(1)(I)for known waste acceptance was used to determine NMOC emission rates for this time period. The equation is provided below: MNMoc=Summation of[2kLOMl(e°)(CNMoc)(3.6 x 10's)]for each year with a known waste acceptance rate MNMoc = Mass emission rate of NMOC, Mg/yr k = Methane generation rate constant, 1/yr = 0.02 t Le = Refuse methane generation potential,ma/Mg = 170.00 2 MI = Mass of solid waste received for given year,Mg = Varies per year(see table below) t, = Age of the i n section,Years = current year minus year of waste placement CNMoc = Concentration of NMOC, ppm as hexane = 153.00 2 Conversion factor = 3.6 x 10'9 NMOC Emission Rate Calculation Summary(for years with known waste acceptance rates) Tons Tons Less Year Received Inert Waste3 M,* t MNMOC 02/01-10/31/2010 578,688 306,704 278,240 1 1.02 11/01-12/31/2010 71,125 37,696 34,198 1 0.13 2011 477,545 345,463 313,402 0 1.17 2012 2013 Totals 1,127,358 689,864 625,840 2.32 Mglyr *Conversion Used: tons to Mg-divide tons by 1.1023 1 For landfills in areas with a thirty year annual average precipitation of less than 25 inches,a k value of 0.02 is to be used. Annual precipitation in the area of North Weld Landfill is about 13 inches,therefore a k value of 0.02 has been used in the NMOC emission rate calculation. 2 For regulatory purposes,the EPA default values for Lo and CNMoc must be used to calculate Tier 1 NMOC emission rates unless actual values have been obtained during Tier 2 sampling. NWLF conducted Tier 2 site specific sampling for CNMOC in 2008(using Method 25C)with a resulting concentration of 153 ppmV as hexane. 6 Inert material includes inert wastes that are disposed in the landfill. 40 CFR 60.754(a)allows the mass of nondegradable material to be subtracted from the total mass of solid waste when calculating the value of M,. NOTE. These calculations are made for NSPS purposes only. EPA has specifically stated as follows:"It is recommended that these default values not be used for estimating landfill emissions for purposes other than N5PS and EG" (61 FR 9905,9912,March 12,1996). Consequently,these emission calculations grossly overestimate actual and potential emissions and reviewers of this document are specifically cautioned against improper and irresponsible uses of these calculations. TOTAL NMOC EMISSION RATE: NMOC rate for years with known waste acceptance rates: 2.32 NMOC rate for years with estimated waste acceptance rates: 7.54 Combined NMOC Emission Rate: 9.86 Mg/yr Page 2 of 2 ®� 2400 West Union Avenue Englewood,CO 80110 303-914.1445(Phone) WASTE MANAGEMENT 303-914-9937(Fax) RECEIVED April 6, 2012 APR 1 1 ?nt, Mr. Charles Johnson Weld County Planning Department Colorado Department of Public Health and Environment GREELEY OFFICE Hazardous Materials and Waste Management Division 4300 Cherry Creek Drive South Denver, CO 80246-1530 Subject: North Weld Landfill (NWLF) Updated Closure and Post-Closure Plan and Financial Assurance Plan Dear Mr. Johnson: Revised closure/post-closure and financial assurance plans are enclosed. The plans have been updated to reflect changes in certain closure/post-closure activities and quantities and miscellaneous text changes. The financial assurance plan includes new closure and post- closure cost estimates, which replace estimates prepared in 2007. Colorado regulations require that cost estimates be replaced with new estimates every five years or as otherwise required by the Colorado Department of Public Health and Environment. Accordingly, the new closure and post-closure cost estimates are in 2012 dollars. A certificate of insurance in the amount of the new estimates is also provided in the financial assurance plan. Copies of the enclosed plans have been placed in the facility operating record. Please call me at (303) 914-1445 if you have questions concerning the enclosures. Sincerely, Tom Schweitzer, P.E. Engineering Manager Enclosures cc: Troy Swain, WCDPHE Kim Ogle, WCDPS Douglas Ikenberry, CDPHE Bill Hedberg/NWLF Operating Record Julie Overmyer, Waste Management of Colorado, w/o enclosures Donna Meals, Waste Management, w/o enclosures C iCAik M 4- is-1 a (90/67-- oia6) C:\Documents and Settings\tschweit\My Documents\mydata\FinAssurancel2\NWLF FinAssur TransLtr 2012.doc CLOSURE/POST-CLOSURE PLAN NORTH WELD LANDFILL Weld County, Colorado Prepared by: Waste Management Disposal Services of Colorado, Inc. North Weld Landfill 40,000 Weld County Road 25 Ault, Colorado ‘00 REG/ �� ss see,- s°yt�o t Reviewed By: .% `Ago 24176 Thomas S:Schweitzer,PE ` e°oy/_,i�a `��`� Registered Professional Engirir/p7N`A�I�Ek\�s �\\ State of Colorado �rrnnnwu��° License#24176 Revised March 2012 CLOSURE/POST-CLOSURE PLAN NORTH WELD LANDFILL TABLE OF CONTENTS Section Page 1.0 INTRODUCTION 1 1.1 PURPOSE 1 1.2 FACILITY INFORMATION 1 2.0 CLOSURE PLAN 2 2.1 INTRODUCTION 2 2.1.1 Description 2 2.1.2 Regulatory Requirements 2 2.2 CLOSURE ACTIVITIES 3 2.3 MAXIMUM EXTENT OF OPERATIONS 4 2.4 FINAL COVER 4 2.4.1 Final Grades 4 2.4.2 Final Cover Description 4 2.5 CONSTRUCTION 5 2.6 CONSTRUCTION QUALITY ASSURANCE(CQA) 5 2.7 CLOSURE SCHEDULE 6 3.0 POST-CLOSURE PLAN 7 3.1 INTRODUCTION 7 3.1.1 Description 7 3.1.2 End Use 7 3.1.3 Regulatory Requirements 7 3.2 POST-CLOSURE ACTIVITIES 8 3.2.1 Facility Management 8 3.2.2 Post-Closure Activities 8 LIST OF FIGURES Figure 1 Site Location Map 2 Closure Area Map 3 Backfill Area Map 4 Post-Closure Drainage Channel 5 Closure Schedule Closure/Post Closure Plan March 2012 North Weld Landfill CLOSURE/POST-CLOSURE PLAN NORTH WELD LANDFILL REVISION LOG DATE DESCRIPTION OF REVISION BY 4/97 Update Plan originally submitted to CDPHE 10/93, to reflect operational TS/AS changes 3/01 Update Plan to increase estimate of largest area of the landfill ever TS/AS requiring final cover during the active life 4/03 Update Plan to increase estimate of largest area of the landfill ever TS/AS requiring final cover during the active life 3/05 Update Plan to increase estimate of largest area of the landfill ever TS/AS requiring final cover during the active life and modify text in Sections 2.4, 2.5 and 2.6 to reflect approval of an alternative final cover design 3/06 Updated Plan to decrease estimate of largest area of the landfill requiring TS/AS final cover during the active life. Miscellaneous text changes were also made to the Plan. 3/07 Updated Plan to reflect changes to the corresponding Financial Assurance TS/AS Plan dated March 2007 specifically replacing cost estimates prepared in 2002 with new cost estimates; updated Plan to adjust estimate of largest area of the landfill requiring final cover during the active life;update soil backfill quantities. Miscellaneous text changes were also made to the Plan. 3/09 Updated Plan to adjust estimate of largest area of the landfill requiring TS/AS final cover during the active life; update soil backfill quantities; included drawing illustrating surface water control structures that remain to be constructed and areas requiring backfill to achieve 5% slope. 3/10 Updated Plan to adjust estimate of largest area of the landfill requiring TS final cover during the active life; updated soil backfill quantities to achieve 5% slope;updated post-closure acreage. 3/11 Updated Plan to adjust estimate of largest area of the landfill requiring TS final cover during the active life; updated post-closure acreage. 3/12 Updated Plan to reflect changes to the corresponding Financial Assurance TS Plan dated March 2012, specifically replacing cost estimates prepared in 2007 with new cost estimates. Miscellaneous text changes. Closure/Post Closure Plan March 2012 North Weld Landfill 1.0 INTRODUCTION 1.1 PURPOSE This Closure/Post-Closure Plan(Plan) for the North Weld Landfill (NWLF)reflects the facility's present understanding of closure and post-closure care requirements for this solid waste disposal site. It has been prepared to meet the following objectives: 1. Describe the steps necessary to close the site when the cost of closure would be the greatest. 2. Describe the activities to be conducted during the post-closure care period. This Plan has been prepared in accordance with the provisions of the Colorado "Regulations Pertaining to Solid Waste Disposal Sites and Facilities", 6 CCR 1007-2 (Regulations). Sections 2.5 and 3.5 of the Regulations pertain to closure activities and Sections 2.6 and 3.6 pertain to post- closure activities. This Plan is to be used in conjunction with the Financial Assurance Plan for NWLF revised March 2012. Cost estimates are calculated in the Financial Assurance Plan for the closure and post-closure care activities described in this Plan. 1.2 FACILITY INFORMATION NWLF is located approximately six miles west of Highway 85, on Colorado Highway 14, in the southwest quarter of Section 7, Township 7 North, Range 66 West, as shown on Figure 1. The facility is owned and operated by Waste Management Disposal Services of Colorado (WMC). The site consists of 170 acres, 119 of which are permitted for municipal solid waste disposal, and an approximate disposal capacity of 15 million bank cubic yards. Current operations are in Phase 3A, Module 2. The facility accepts non-hazardous municipal, commercial and industrial solid wastes. NWLF is being developed in four phases: 1, 2, 3A and 3B. The site will be closed and monitored as a single unit. Individual phases will not be closed or monitored separately; therefore, this plan addresses the site as a whole. However, operational factors occurring during the life of the site may necessitate closure or monitoring of portions of the site individually. Closure/Post Closure Plan 1 March 2012 North Weld Landfill • 2.0 CLOSURE PLAN 2.1 INTRODUCTION 2.1.1 Description This closure plan describes the steps necessary to close the facility at any point during its active life. This plan will be reviewed and updated as needed for changing conditions. 2.1.2 Regulatory Requirements This closure plan is prepared in accordance with Section 2.5, "Closure of Solid Waste Disposal Sites and Facilities"and Section 3.5, "Closure"of the Regulations. This plan will be maintained in the facility operating record. The closure requirements call for a closure plan, a description of the closure activities and the closure certification. The requirements are summarized below: Closure Plan 1. Prepare a closure plan for approval by the CDPHE after consultation with the local governing body having jurisdiction. The plan, at a minimum, must include the following: a. The steps necessary to close the landfill at any point during its active life. b. A description of the final cover system and the methods and procedures to be used to install the cover. c. An estimate of the largest area of the landfill ever requiring a final cover during the active life. d. A schedule for completing closure activities. 2. Maintain a copy of the closure plan in the operating record. Closure Activities 1. Close the site in accordance with the Solid Waste Disposal Sites and Facilities Act and the Regulations. 2. Sixty(60) days prior to closure notify the CDPHE and the local governing body in writing that the facility will be closing. 3. Sixty(60) days prior to closure notify the general public of the facility closure by posting clearly visible signs of suitable size at the site entrance. 4. Enact precautions to prevent further use of the site for unauthorized disposal. Closure/Post Closure Plan 2 March 2012 North Weld Landfill 5. Prevent water pollution from occurring at or beyond the point of compliance. 6. Prevent nuisance conditions at or beyond the site boundary. 7. Initiate closure activities within thirty(30) days of reaching final design grades unless an extension is obtained from CDPHE. 8. Complete closure within 180 days after closure initiation, or if necessary, obtain an extension from the CDPHE. Closure Certification 1. Following closure, submit a report certified by a Colorado professional engineer (P.E.)to the CDPHE documenting that closure has been completed in accordance with the closure plan. Place a copy of the report in the facility operating record. 2. Following closure, record a notation on the deed or other title instrument stating that the land was used as a landfill and its use is restricted. Notify the CDPHE and the local governing authority that the notation has been recorded and place a copy of the notation in the operating record. 2.2 CLOSURE ACTIVITIES The following closure activities will be performed when site closure is necessary: 1. Construction Documents—Closure construction plans will be prepared as needed. 2. Regulatory Agency Notification- Sixty(60) days prior to closure of any landfill phase, a notification of the intent to close will be submitted to the CDPHE and the local governing authority and a copy of the notice will be placed in the operating record. 3. Public Notification - Sixty (60) days in advance of closure date, signs will be placed at entrance to the site notifying the general public of the closure date. 4. Final Cover- Final cover will be placed in accordance with the Regulations. The final cover design is discussed in detail in Section 2.3 of this Plan. 5. Completion of Closure- Closure activities will be completed within 180 days following closure. A request for an extension maybe submitted to CDPHE if climatic or operational factors dictate that additional time is required for proper closure. 6. Certification/Documentation - Upon completion of construction, a report will be prepared Closure/Post Closure Plan 3 March 2012 North Weld Landfill by a Colorado P.E. certifying that closure was conducted in accordance with the provisions of this plan. The report will be submitted to CDPHE for approval after consultation with the local governing board. The approved report will be placed in the operating record. To complete closure a notation will be made on the title or deed to the land, which notifies prospective buyers that the land was used as a landfill, and that certain land use restrictions apply. Copies of the notation will be submitted to CDPHE and the local governing body and a copy will also be placed in the operating record. 7. Security- During closure activities and after closure,public disposal will be prohibited. Signs will be posted warning of unauthorized entry or waste disposal. The existing fence will be maintained and the front gate will be kept locked when not in use. 2.3 MAXIMUM EXTENT OF OPERATIONS An estimate of the largest area of the landfill currently requiring final cover is about 76 acres in Phases 1, 2 and 3A as shown in Figure 2. The estimated 76 acre closure area is based on the facility's current disposal activities, less 16 acres of final cover completed in 2006. 2.4 FINAL COVER 2.4.1 Final Grades Final grades have been designed to promote surface water runoff and minimize erosion. Final grade slopes are designed to be a minimum of 5 percent(20 to 1) and a maximum of 25 percent (4 to 1), unless alternative grades have been approved by CDPHE. Prior to placement of final cover, areas of the site that have not been filled to final grades may require placement of backfill to achieve 5% slopes. About 250,000 cubic yards of on- site soils are estimated for achieving minimal slopes prior to placement of final cover. Figure 3 shows the area of backfill needed to achieve 5% slopes. 2.4.2 Final Cover Description NWLF received approval from CDPHE and Weld County Department of Public Health and Environment (WCDPHE) for an alternative final cover (AFC) design on March 30, 2004 and September 3, 2004 respectively. The AFC components are described below. 1. Alternative Final Cover Layer-The AFC layer will consist of a minimum of 18 inches of slightly compacted soil from on-site sources. AFC thickness on the side slope will be increased to 20 inches in accordance with the AFC design. The AFC components should have no less than 15% fines content and be compacted to between 80%to 90% of maximum density as determined by Standard Proctor (ASTM D 698). Approximately 195,000 cubic yards of soil will be necessary for the AFC layer. This assumes an average 19-inch AFC layer will be installed over the 76-acre area. Closure/Post Closure Plan 4 March 2012 North Weld Landfill 2. Alternative Final Cover Topsoil Layer—The 6-inch topsoil layer of the AFC will have no less than 30% fines content and be compacted to between 80% and 90%of maximum density as determined by Standard Proctor(ASTM D698). The 6-inch topsoil layer of the AFC will be material suitable for sustaining vegetation. AFC seedbed preparation, seed mix and fertilizer requirements are specified in the approved"North Weld Landfill Alternative Final Cover Demonstration"prepared by Golder Associates dated December 30, 2003. Approximately 62,000 cubic yards of soil will be required for the topsoil layer over the 76-acre area. 2.5 CONSTRUCTION Construction of the final cover system will be performed by using equipment such as scrapers to excavate, haul and place loose soil lifts for the AFC layer. A motor grader, low ground pressure dozer, or other suitable equipment will be used to spread/shape the cover. The topsoil layer will be placed loosely over the AFC layer with scrapers and then shaped with a motor grader, low ground pressure dozer, or other suitable equipment. The topsoil layer will then be prepared in accordance with specifications provided in the above referenced North Weld Landfill Alternative Final Cover Demonstration. 2.6 CONSTRUCTION QUALITY ASSURANCE (CQA) To ensure proper implementation of the AFC design the following CQA requirements apply: o Performance of grain-size distribution tests every 5,000 cubic yards will be conducted for the AFC layer and the 0.5 foot topsoil layer; o Performance of Standard Proctor tests every 10,000 cubic yards; e In-situ density testing using a nuclear gauge at a frequency of one test per 1,000 cubic yards; o Oven-dry moisture contents at a frequency of one test every 1,000 cubic yards; • Verification of proper thickness of cover at a grid spacing of approximately 100 feet on-center. A design drawing showing the area of AFC to be built and a detail of the cover cross-section will be supplied to the CDPHE and WCDPHE prior to construction. Also, an as-built construction drawing will be provided with the certification report that shows the survey points used to verify thickness on the approximately 100 feet on-center grid pattern. Upon completion of construction activities, a Colorado P.E. will sign a certification Closure/Post Closure Plan 5 March 2012 North Weld Landfill document indicating that the final cover was constructed in substantial conformance with the project specifications and approved closure plan. 2.7 CLOSURE SCHEDULE The schedule for closure is weather dependent. Excessive cold or rainy weather can affect placement of cover materials. The typical available construction window for placing cover materials in this climate is from late April through late September. A typical closure schedule is provided in Figure 5. If necessary, a request for an extension will be submitted to CDPHE to ensure that sufficient time is available to complete closure in accordance with the provisions of this closure plan. Closure/Post Closure Plan 6 March 2012 North Weld Landfill 3.0 POST-CLOSURE PLAN 3.1 INTRODUCTION 3.1.1 Description This post-closure plan describes all actions to be taken following closure of the site. Post- closure care begins after the site is closed in accordance with the closure plan. Post-closure care continues for a period of 30 years, unless during the life of the facility or the post- closure period, a demonstration is made to the CDPHE and the local governing body, which shows that a reduced time period is sufficient to protect human health and the environment. If the post-closure period is reduced, this plan will be updated accordingly. 3.1.2 End Use Upon completion of closure, current plans indicate that the site will be zoned for agricultural use. This end use should have minimal impact on the final cover, and the use will not interfere with post-closure monitoring. 3.1.3 Regulatory Requirements This post-closure plan is prepared in accordance with Section 2.6 "Post-Closure Care and Maintenance Standards"and Section 3.6, "Post-Closure Care and Maintenance"of the Regulations. This plan will be maintained in the facility operating record. The regulatory requirements are summarized below: Post-Closure Plan 1. Prepare a post-closure plan for approval by CDPHE in consultation with the local governing body, which includes the provisions to prevent or minimize nuisance conditions,maintain the final cover, monitor groundwater, maintain and monitor the leachate collection system, and monitor landfill gas. 2. Describe the planned end use for the site and identify the name and address of a contact person who is responsible for the facility. 3. Maintain a copy of the post-closure plan in the site's operating record. Post-Closure Activities 1. The post-closure period shall be at least 30 years unless a demonstration is made to CDPHE and the local governing body that a shorter time period is sufficient to protect human health and the environment. 2. Permanent surface water structures remaining after closure shall be designed to manage run-on and run-off from a 100 year, 24-hour storm event. Figure 4 shows the general location of permanent stormwater channels anticipated to be Closure/Post Closure Plan 7 March 2012 North Weld Landfill constructed as part of closure activities. 3. Enact precautions to prevent water pollution at the point of compliance after closure. 4. Enact precautions to prevent nuisance conditions at or beyond the site boundary after closure. 5. Post-closure monitoring shall be conducted in accordance with the approved post-closure monitoring plan. 6. At the completion of the post-closure care period, a notification will be submitted to CDPHE with a certification signed by an independent Colorado Registered Professional Engineer or approved by the CDPHE and the local governing body having jurisdiction verifying that post-closure care has been completed in accordance with the post-closure plan. The notification will be placed in the operating record. 3.2 POST-CLOSURE ACTIVITIES 3.2.1 Facility Management During the post-closure period, a facility manager will be named and a phone number and address for the manager will be incorporated into this plan. The manager currently responsible for the facility is: Mr. William Hedberg North Weld Sanitary Landfill 40,000 WCR 25 Ault, Colorado (970) 686-2800 3.2.2 Post-Closure Activities The following post-closure activities provide for inspection, maintenance, and monitoring of the design features of the facility during the post-closure period: 1. Inspections - Inspections of the site will be conducted quarterly for the first two years after closure and semi-annually thereafter. The inspector will assess the conditions of the site and recommend corrective actions for any items needing attention. Items to be inspected are further described in the following line items and include nuisance conditions, the final cover system, groundwater monitoring points, leachate monitoring system, gas monitoring system, surface water management system, and security. Closure/Post Closure Plan 8 March 2012 North Weld Landfill 2. Prevent Nuisance Conditions - The placement of final cover provides a barrier between the refuse and the environment. Construction of the final cover in substantial conformance with the project specifications should prevent disease vectors,deter birds, minimize odors, reduce blowing litter, and minimize air and water pollution as direct contact with refuse is prevented. Inspections and continued maintenance of the final cover system will ensure the integrity of the final cover so nuisance conditions are prevented throughout the post-closure period. The potential for on-site litter, traffic congestion, and noise pollution will be eliminated once the closure of the facility is complete since refuse will no longer be accepted for disposal and heavy equipment will no longer be operating. 3. Final Cover System-The maintenance of the final cover may involve repair of the AFC layer, the erosion layer and vegetation. It is estimated that 5%of the site per year will require cover maintenance, reseeding and fertilizer. An additional 5%is estimated, which will allow for 10%of the site for the first 2 years of post-closure for cover maintenance, reseeding and fertilizer. Additionally, NWLF will conduct a qualitative vegetation assessment annually during post-closure to ensure the vegetative cover is established and assist in identifying any areas that may require attention. 4. Groundwater Monitoring- The current groundwater monitoring program consists of 5 wells, which will be monitored in accordance with the Site Specific Groundwater Monitoring Plan (GWMP). Depending on the monitoring analytical data obtained during the site operating period, the number of wells and the monitoring frequency may be reduced during the post-closure care period with concurrence by CDPHE and the local governing authority. For this plan it is estimated that groundwater monitoring will be performed semi-annually. Samples will be analyzed for the constituents listed in the Groundwater Management Plan. The results of all analysis will be placed in the site's operating record. Monitoring results will be reviewed and a statistical evaluation performed comparing each event's results to background levels. Detection monitoring will continue as long as results remain below specified levels for each constituent. If the statistical evaluation shows that background levels are exceeded, confirmation sampling, and if necessary, corrective action will be performed in accordance with the GWMP and this plan will be updated as necessary. In addition to sampling, it is estimated that one well will require repair each year and a new pump will be required every five years. The integrity of the monitoring well system will be inspected during the monitoring events or during the annual site inspections. Any required repairs will be corrected. 5. Leachate Monitoring- The liquid elevation in the leachate collection sumps will Closure/Post Closure Plan 9 March 2012 North Weld Landfill be monitored semi-annually to verify the levels are 1 ft or less above the base liner. The measurements will be taken concurrent with semi-annual groundwater monitoring or site inspection activities. Leachate samples from the sumps will be taken annually for analysis, if leachate is present. Although leachate is not expected during post-closure, in the event that leachate is removed from a sump, it will be managed in accordance with the analytical data and approved leachate management procedures. Information related to the number of gallons removed, date, time, and location of leachate removal, and the disposal method will be maintained in the facility operating record. Due to the and climate leachate generation is not expected at closure. Nevertheless, during the post-closure period, an allowance for leachate management is provided for the first 5 years of post-closure in the event of premature closure. A demonstration may be made to the CDPHE showing that the leachate no longer poses a threat to human health and the environment and that monitoring can cease. 6. Gas Monitoring - The facility will continue to monitor gas at the site quarterly in accordance with the Landfill Gas Migration Monitoring Plan(LGMMP). The post- closure cost estimate assumes the 15 gas monitoring probes (currently in the program)will be monitored during post-closure. Based on the monitoring data obtained during the site operating period, the number of probes and the frequency of monitoring may be reduced during the post-closure care period with concurrence by CDPHE and the local governing authority. Results from each gas monitoring event will be placed in the site's operating record. If monitoring results indicate that methane gas is present above the permissible regulatory limits, measures will be taken in accordance with Section 2.3.3 of the Regulations. 7. Surface Water Management System - Maintenance of the surface water management system is expected to be required during the post-closure period. This maintenance consists of regrading or desilting channels and ponds. In addition, semi-annual inspections of the stormwater system will be performed. Inspections of permanent stormwater management structures will be performed following storm events exceeding the 100 year, 24 hour storm event. 8. Waste Disposal - Off-site refuse will not be accepted during the post-closure period. However, if during post-closure repairs, previously placed refuse is excavated for construction activities, the refuse will be placed within the permitted fill area and final cover will be applied. 9. Security- During post-closure, the perimeter fence will remain in place and the front gate locked when not in use. Signs will be posted warning of unauthorized entry. Closure/Post Closure Plan 10 March 2012 North Weld Landfill The integrity of the fence will be monitored and maintenance performed as necessary. 10. Certification - At the completion of the post-closure care period, a notification will be submitted to CDPHE with a certification signed by an independent Colorado Registered Professional Engineer or approved by the CDPHE and the local governing body having jurisdiction verifying that post-closure care has been completed in accordance with the post-closure plan. The notification will be placed in the operating record. Closure/Post Closure Plan 11 March 2012 North Weld Landfill FIGURES m�rs3-•91!" 'cxs:",,#. . -wS - ,tT'S� OMot'M,:e ".f,raGM+Nra ' ,^Y-9.NtiV GIE',Y :a:•I:pY+. �.r „ .,'R^r,.^'I-0 ■ t ,, ,_ . . 'e `■ ■■■■■■■■ , '.[�_VkLL: NIIIII lid ,=7 . �'`■■ ■ 1 lima m 1 Ii tam ■ a , a ■■'' =^ 1 'J■ '� IYr�i�iri■�■ ■ i , All allithlriala ; s 41 ■.1".... am. Oar, !1gnLnm.mmaau 4Z w: --31 i. _mss ifr!iS .'Illitialtoricallmai Ma I ' ilinlIM.I,Lti . ' "V"Inal e Iiiintr - lag _s____,.. 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North Weld Landfill 40,000 Weld County Road 25 Ault, Colorado Revised March 2012 FINANCIAL ASSURANCE PLAN NORTH WELD LANDFILL TABLE OF CONTENTS Section Page 1.0 INTRODUCTION 1 2.0 REGULATORY REQUIREMENTS 1 2.1 Cost Estimates 1 2.2 Financial Assurance Activities 1 2.3 Financial Assurance Mechanisms 2 3.0 CLOSURE AND POST-CLOSURE COSTS 2 4.0 FINANCIAL ASSURANCE MECHANISM 2 LIST OF APPENDICES Appendix A Closure Costs B Post-Closure Care Costs C Insurance Certificate for Closure and Post-Closure Care Costs Financial Assurance Plan i March 2012 North Weld Landfill FINANCIAL ASSURANCE PLAN NORTH WELD LANDFILL REVISION LOG DATE DESCRIPTION OF REVISION BY 4/99 Replaced letter of credit with insurance certificate. TS 3/01 Revise financial assurance costs based on the revised closure and post- TS/AS closure plan dated March 2001. 5/02 Replace original engineering cost estimates of closure and post-closure TS/AS based on 2002 CDPHE guidance or determined by NWSL 4/03 Revise financial assurance costs based on the revised closure and post- TS/AS closure plan dated April 2003. 3/05 Revise financial assurance costs based on the revised closure and post- TS/AS closure plan dated March 2005 3/06 Revised financial assurance costs based on the revised closure and post- TS/AS closure plan dated March 2006. 3/07 Replace cost estimates of closure and post-closure prepared in 2002 with TS/AS new cost estimates in accordance with Section 1.8.3 of the Solid Waste Regulations. Miscellaneous text changes were also made to the Plan. 3/09 Revised financial assurance costs based on the revised closure and post- TS/AS closure plan dated March 2009. 3/10 Revised financial assurance costs based on the revised closure and post- TS closure plan dated March 2010. 3/11 Revised fmancial assurance costs based on the revised closure and post- TS closure plan dated March 2011. 3/12 Replaced cost estimates of closure and post-closure prepared in 2007 with TS new cost estimates in accordance with Section 1.8.3 of the Solid Waste Regulations. Miscellaneous text changes were also made to the Plan. Financial Assurance Plan ii March 2012 North Weld Landfill 1.0 INTRODUCTION This Financial Assurance Plan (Plan) has been prepared in accordance with Section 1.8 of the Regulations Pertaining to Solid Waste Disposal Sites and Facilities, 6 CCR 1007-2, (Regulations), and sets forth the closure and post-closure care costs for North Weld Landfill (NWLF) in Ault, Colorado. This Plan includes, in Appendices A and B, new closure and post-closure cost estimates which replace all previous estimates. The Regulations require that cost estimates be replaced every five (5) years or as otherwise required by the Colorado Department of Public Health and Environment (CDPHE) and 2012 marks the fifth year since costs were replaced. The next replacement of cost estimates is scheduled for 2017. This Plan also describes the financial assurance mechanism in place to ensure payment of all associated closure and post-closure costs. This Plan is to be used in conjunction with the NWLF Closure/Post Closure Plan dated March 2012. 2.0 REGULATORY REQUIREMENTS 2.1 Cost Estimates Sections 1.8 of the Regulations list the specific financial assurance requirements for solid waste disposal sites. These requirements are described below: 1. Maintain cost estimates, in current dollars, for hiring a third party to close the largest area of the facility requiring closure during the active life of the site. The cost estimate must also include costs associated with conducting post-closure care. 2. The facility must establish financial assurance sufficient to ensure payment of the closure and post-closure care costs. 2.2 Financial Assurance Activities The following are the requirements for financial assurance activities as described in Section 1.8 of the Regulations: 1. Notify CDPHE when the required cost estimates have been placed in the operating record; 2. Annually adjust cost estimates to account for inflation using the method prescribed by CDPHE; 3. Replace original cost estimates with new cost estimates every five (5) years, unless otherwise required by CDPHE; 4. Costs associated with closure, post-closure and corrective actions may be adjusted, after approval by CDPHE and the local governing authority; Financial Assurance Plan 1 March 2012 North Weld Landfill 5. Financial assurance must be provided continuously unless a release is granted by CDPHE. 2.3 Financial Assurance Mechanisms Several financial assurance mechanisms are available, and more than one mechanism may be used. For corporate entities, these mechanisms include a trust fund, letter of credit, surety bond and insurance. Waste Management Disposal Services of Colorado, Inc. (WMC) has chosen to use insurance to meet the financial assurance requirements. The insurance certificate was prepared in accordance with the requirements set forth in Section 1.8.9 of the Regulations. 3.0 CLOSURE AND POST-CLOSURE COSTS Closure and post-closure costs are those costs associated with closing the facility and conducting post-closure care activities. These costs are determined by calculating the cost to complete all of the actions in the Closure/Post Closure Plan. The unit cost values for closure and post-closure activities were determined by WMC. Costs for items including earthwork, excavation and soil placement, were taken from recent bids for similar work completed at Waste Management construction projects. The new closure costs are provided in Appendix A, and the post-closure costs are provided in Appendix B. 4.0 FINANCIAL ASSURANCE MECHANISM WMC has established insurance coverage to assure adequate funds are available for all closure and post closure care costs determined in the Closure/Post-Closure Plan. The insurance meets all requirements set forth in Section 1.8.9 of the Regulations, "Insurance for Closure and Post- Closure". The insurance certificate is provided in Appendix C. • Financial Assurance Plan 2 March 2012 North Weld Landfill APPENDIX A CLOSURE COSTS TABLE 1 -CLOSURE COST ESTIMATE Date: March-12 Site: NORTH WELD LANDFILL Page: 1 Unit Cost Extended category Item Description Units Quantity Note 1) Cost Cost 1 Foundation Layer a Backfill of intermediate grades to achieve CY 250,000 1.85 462,500 minimum 5% slope (on-site source) b Other Foundation Layer Closure Costs 0 Foundation Layer Total Cost 462,500 2 Final Cover Section Closure Area: 76.0 Acres a Compacted Clay Layer (on-site source) CY 0 b Alternative Final Cover(on-site source) CY 195,000 1.85 360,750 c Topsoil (on-site source) CY 62,000 1.85 114,700 d Fertilizer/Soil Amendements/material hauling Acre 76.0 834.00 63,384 e Seeding Acre 76.0 620.00 47,120 f Other Final Cover Closure-Related Costs Acre 0 Final Cover Total Cost 585,954 3 Surface Water Controls a Drainage Swales/Berms/Channels LF 3,855 20.48 78,950 b Culverts LF 210 104.00 21,840 c Sedimentation/Surface Wtr Control Ponds 0 d Erosion Control 0 e Other Surface Water Closure-Related Costs 0 Surface Water Total Cost 100,790 4 Environmental Monitoring Installations a Grndwtr Mntq Wells w/dedicated pumps EA 0 b Gas Monitoring Probes EA 0 c Other Env. Monitoring Closure Costs 0 Environmental Monitoring Total Cost 0 5 Gas Collection and Control System (GCCS) a Extraction Well Installation 0 b Extraction Well -Well Head Assembly 0 c Extraction Well - Lateral Pipe 0 d GasNapor Collection - Header Pipe 0 e GasNapor Collection - Header Drain 0 f Blower 0 g Blower Enclosure/Building 0 h Flare 0 i Other GCCS Closure-Related Items 0 GCCS Total Cost 0 TABLE 1 -CLOSURE COST ESTIMATE (Continued) Date: March-12 Site: NORTH WELD LANDFILL Page: 2 Item Description Units Quantity Unit Cost Extended category (Note 1) COSt Cost 6 Miscellaneous Closure Activities a Access Road Construction 0 b Fencing 0 c Signs EA 2 150.00 300 d Other Miscellaneous Closure-Related Items 0 Miscellaneous Total Cost 300 7 CLOSURE COST ESTIMATE SUBTOTAL 1,149,544 8 Eng neering & Project Management a Design & Bid Documents (% of Subtotal) 3% 34,486 b CQA, Surveys & Reports (% of Subtotal) 10% 114,954 c Project Mgmt&Admin (% of Subtotal) 2% 22,991 Engineering & Project Mgmt Total Cost 172,432 9 Contingency (% of Subtotal) 10% 114,954 10 CLOSURE COST ESTIMATE TOTAL (in 2012 dollars) $1,436,931 11 Inflation Adjustment Factor for 2013 12 Inflation Adjustment Factor for 2014 13 Inflation Adjustment Factor for 2015 14 Inflation Adjustment Factor for 2016 Total Closure Cost $1,436,931 Notes: 1 All costs include material and installation unless noted otherwise. APPENDIX B POST-CLOSURE CARE COSTS TABLE 2-POST-CLOSURE COST ESTIMATE Date: March-12 Site: NORTH WELD LANDFILL Acres at Closure: 92 Item Description Units Unit Unit Cost Quantity Cost per Quantity per Year Year 1a Facility Inspections& Reporting-2 per year EA 1 1,150 2 2,300 lb Facility Inspections&Reporting-2 addt'I Annual cost far 2 addt'I events=2,300 events to allow for qtrly inspections first Total Item cost for 2-yr period=4,600 2 yrs of post-closure. Total Item cost annualized over 30-yr PC period= 153 2 Qualitative Vegetative Assessement-annual EA 1 3,312 1 3,312 3a Cover Maintenance, Reseeding& Fertilizing- AC 5% 2,181 4.6 10,033 5%of site per year(Note 1) 3b Cover Maintenance, Reseeding&Fertilizing- Annual cost for addt'l 5%= 10,033 addt'I 5%per year to allow for 10%of the Total Item cost for 2-yr period= 20,065 site first 2 yrs of post-closure Total Item cost annualized over 30-yr PC period= 669 4 Surface Water Controls-Maintenance LS 1,000 1 1,000 5 Fence Repair LS 500 1 500 6 Mowing-Assume annual mowing for first 10 AC 1 40 92 years of post-closure Annual mowing cost= 3,680 Cost for 10 mowing events= 36,800 Total Item cost annualized over 30-yr PC period= 1,227 7 Groundwater Monitoring-Semi-annual events EA 5 1,723 2 17,230 8 Groundwater Well Pump Repair/Maintenance LS 300 1 300 9 Gas Probe Monitoring, Maintenance and EA 15 87 4 5,220 Reporting-4 Events per Year 10 Leachate Monitoring-Annual EA 3 461 1 1,383 11 Leachate Depth Measurement-Semi-annual EA 3 554 2 3,324 12 Leachate Management-First 5 years of post- Annual cost for leachate mgmt= 5,000 closure(managed on-site)(Note 2) Total Item cost for 5-yr period= 25,000 Total Item cost annualized over 30-yr PC period= 833 13 Gas Collection and Control Syst Maint LS 0 14 Gas Condensate Disposal GAL 0 15 Subtotal-Items 1 through 14 47,484 16 Administrative Costs(%of Subtotal) 5% 2,374 17 Contingency(%of Subtotal) 10% 4,748 18 Total Cost per Year 54,606 19 Post-Closure Care Period: 30 Years 20 Total Post-Closure Cost(in 2012 dollars) $1,638,190 21 Inflation Adjustment Factor for 2013 22 Inflation Adjustment Factor for 2014 23 Inflation Adjustment Factor for 2015 24 Inflation Adjustment Factor for 2016 Total Post-Closure Cost $1,638,190 Notes 1 Unit cost for Item 3 is based on the Fertilizer,Soil Amendment and Seeding costs of the Closure Cost Estimate(Table 1)increased by a factor of 1 5 to provide an allowance for cover maintenace in addition to seeding,fertilizer and amendments 2 Due to arid climate,leachate generation is not expected at closure. However an annual allowance for leachate management is provided for the first 5 years of post-closure in the event of premature closure. Basis for Costs Line la $1.150 based on 9 hrs for site inspector @$70/hr and 3 hrs for report preparation @$120/hr plus clerical to write report 2 $3.212 vegetation assessement based on actual CSLF 3rd party costs for this service 3a $2.181 based on Table 1,Line 2d and 2e values increased by a factor of 1.5 4&5 Estimated values 6 $40/acre mowing cost based on 3rd party bid submitted to DADS 7 Based on actual 3rd party sampling and lab costs • 8 Estimated value 9 Based on representative 3rd party costs from other Colorado WM landfills 10 Based on actual 3rd party sampling costs 11 Based on actual 3rd party costs APPENDIX C INSURANCE CERTIFICATE FOR CLOSURE AND POST-CLOSURE CARE COSTS 2012 CLOSURE AND POST-CLOSURE COST ESTIMATES The NWSL Financial Assuarance Plan as revised March 2012 includes a closure cost estimate of $1,436,931 (Appendix A) and a post-closure cost estimate of$1,638,190 (Appendix B) for a combined total estimate of$3,075,121. These estimates are based on the site Closure and Post- Closure Plan dated March 2012. The accompanying insurance certificate reflects this adjusted amount. ACORDTM CERTIFICATE OF LIABILITY INSURANCE D0E(MMID013 PRODUCER THIS CERTIFICATE IS ISSUED AS A MATTER OF INFORMATION National Guaranty insurance Company of Vermont ONLY AND CONFERS NO RIGHTS UPON THE CERTIFICATE HOLDER. THIS CERTIFICATE DOES NOT AMEND, EXTEND OR 100 Bank Street, Suite 610 ALTER THE COVERAGE AFFORDED BY THE POLICIES BELOW. Burlington, Vermont 05401 (802) 864-1715 INSURERS AFFORDING COVERAGE NAIC# INSURED INSURER A: National Guaranty Insurance Company Waste Management Disposal Services of Colorado, Inc. INSURER B: of Vermont 5500 South Quebec Street, Suite 250 INSURER C: Greenwood Village, Colorado 80111 INSURER D: INSURER E: COVERAGES THE POLICIES OF INSURANCE LISTED BELOW HAVE BEEN ISSUED TO THE INSURED NAMED ABOVE FOR THE POLICY PERIOD INDICATED.NOTWITHSTANDING ANY REQUIREMENT,TERM OR CONDITION OF ANY CONTRACT OR OTHER DOCUMENT WITH RESPECT TO WHICH THIS CERTIFICATE MAY BE ISSUED OR MAY PERTAIN,THE INSURANCE AFFORDED BY THE POLICIES DESCRIBED HEREIN IS SUBJECT TO ALL THE TERMS,EXCLUSIONS AND CONDITIONS OF SUCH POLICIES.AGGREGATE LIMITS SHOWN MAY HAVE BEEN REDUCED BY PAID CLAIMS. INSR ADD'L POLICYNUMBER POLICY EFFECTIVE POLICY EXPIRATION LIMITS LTR UISRQ TYPE OF INSURANCE DATEIMM/DD/YY1 DATEIMM/DDIYYJ GENERAL LIABILITY EACH OCCURRENCE $ DAMAGE TO RENTED COMMERCIAL GENERAL LIABILITY PREMISES(Eaocaxence) $ CLAIMS MADE r OCCUR MED EXP(Anyone person) $ PERSONAL 8 AM/INJURY $ GENERAL AGGREGATE $ GEN'L AGGREGATE LIMIT APPLIES PER: PRODUCTS-COMP/OP AGG $ —7 POLICY 7 ECT f]LOC AUTOMOBILE UABIUTY COMBINED SINGLE LIMIT $ ANY AUTO (Ea accident) ALL OWNED AUTOS BODILY INJURY SCHEDULED AUTOS (Per person) HIRED AUTOS BOOILYINJURY $ NON-OWNED AUTOS (Per accident) PROPERTY DAMAGE (Per accident) GARAGE LIABILITY AUTO ONLY-EA ACCIDENT $ ANY AUTO OTHER THAN EA ACC $ AUTO ONLY: AGG $ EXCESS/UMBRELLA LIABILITY EACH OCCURRENCE $ OCCUR CLAIMS MADE AGGREGATE S S _ DEDUCTIBLE $ RETENTION $ l $ WORKERS COMPENSATION AND I TORY LAM FS I IOER EMPLOYERS'LIABILITY E.L.EACH ACCIDENT ANY PROPRIETOR/PARTNER/EXECUTVE S OFFICER/MEMBER EXCLUDED? E.L.DISEASE-EA EMPLOYEE $ II yes,describe under SPECIAL PROVISIONS below E.L.DISEASE-POLICY LIMIT $ OTHER A Closure CPCS99-0013 4/09/99 4/09/13 $1,436,931.00 Post-Closure l$1,638,190.00 DESCRIPTION OF OPERATIONS/LOCATIONS/VEHICLES/EXCLUSIONS ADDED BY ENDORSEMENT/SPECIAL PROVISIONS North Weld Sanitary Landfill, 40000 Weld County Road 25, Ault, CO 80610 This certificate certifies that the policy to which this certificate applies provides closure and/or post-closure care in connection with the Insured's obligation to demonstrate financial responsibility under Section 1.8.9 of the regulations pertaining to Solid Waste Disposal Sites and Facilities 6 CCR 1007-2, as amended. CERTIFICATE HOLDER CANCELLATION Director SHOULD ANY OF THE ABOVE DESCRIBED POLICIES BE CANCELLED BEFORE THE EXPIRATION Colorado Department of Public Health and Environment DATE THEREOF,THE ISSUING INSURER WILLXNDeitAXOX TO MAIL 120 DAYS WRITTEN Hazardous Materials/Waste Management Division NOTICE TO THE CERTIFICATE HOLDER NAMED TO THE LEFT,RIR MILIIRQ(16)IcKSN$�IXLK 4300 Cherry Creek Drive South XIIm$e,IQQ(t7eocontD�1\ 8(Llrl% Nt(0PX1K013 II 1311 Gt lMOIC Denver, Colorado 80246-1530 REgBEISINRAAVEs( L \.),4 q AUTHORIZED REPRESENTATIVE Donna L. Meals,Vice President and secretary ACORD 25(2001/08) ©ACORD CORPORATION 1988 2400 West Union Avenue Englewood, CO 80110 303-914-1445(Phone) WASTE MANAGEMENT 866.442-0285(Fax) RECEIVED APR 1 7 7n1, Weld zpartment April 13, 2012 „r 'CF Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, CO 80246-1530 Mr. Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, CO 80631 SUBJECT: NORTH WELD LANDFILL FIRST QUARTER 2012 LANDFILL GAS (Methane) MONITORING REPORT Dear Mr. Henderson and Mr. Swain: Enclosed for your information is the First Quarter 2012 Gas Monitoring Report for North Weld Landfill (NWLF). The report dated March 13, 2012 was prepared by AquAeTer and documents their field monitoring activities conducted between March 5 and 12, 2012 for monitoring the subsurface and facility structures for methane migration in accordance with 6 CCR 1007-2. The gas monitoring report contains monitoring results from the Phase 1 and 2 perimeter soil gas probes GP-06, GP-07, GP-10 through GP-20, structure probes GP-01 and GP-02, inside the shop and office, and confined spaces in the vicinity of the western boundary of the site. A map showing the gas probe locations, the scale house and maintenance shop is included as Figure 1. Section 2.3.1 of the Regulations Pertaining to Solid Waste Sites and Facilities, 6 CCR 1007-2, Part 1 (Regulations) requires that the percent of methane (explosive gas) in air (v/v) shall not exceed (A) 25% of the lower explosive limit (LEL) (i.e., 1.25% methane v/v) within facility structures, and (B)the LEL (i.e., greater than 5% methane v/v) at the facility boundary. During this monitoring event, methane was detected in perimeter probe GP-06 at 5.2% v/v and structure probe GP-01 at 21.0% v/v. Although below regulatory limits, methane was also detected in probes GP-12 at 3.2% v/v and GP-16 at 0.3% v/v. Methane was not detected in any of the other probes, shop, office or confined spaces during the first Quarter 2012 monitoring event. The facility currently operates under an approved gas remediation plan prepared in response to previous elevated methane concentrations in structure probe GP-01 and perimeter probes GP-10 and GP-11. The plan includes monthly monitoring of these probes and utility corridor access points along WCR 25. Beginning in February 2012, the facility also began monthly monitoring of Qc,r,,4,.Uv ,r cti ,;u\a- - • Letter Jerry Henderson and Troy Swain April 13, 2012 Page 2 GP-06. Included in Attachment 1 are the January and February 2012 monthly reports. A summary of the monitoring results for these monthly events is provided in the following table. Percent (%) CH4 v/v Monitoring Probe January 2012 February 2012 GP-01 10.5 10.2 GP-06 NA 4.9 GP-10 0.0 8.5 GP-11 0.0 0.0 Methane was not detected in the utility corridor access points or facility structures during the monthly monitoring. The approved remediation plan also included the installation and operation of passive gas vents constructed within waste along the western limit of the disposal area. As stated in the plan, the passive vents, which were installed in December 2009, may require one or more years to show consistent reduction in methane levels at perimeter probes GP-10 and GP-11 and structure probe GP-01. Until methane levels are below the regulatory threshold for three consecutive monthly events, monthly monitoring will continue to be performed. As previously indicated, GP-06 was added to the monthly monitoring program commencing in February 2012. Continuous methane monitors are in operation within the facility maintenance building, office and gatehouse and no methane detections have been observed. We have been evaluating options to augment the performance of the existing in waste passive gas vents in order to increase their radius of influence in the southwest corner of the disposal area. We have determined that replacing the wind turbines presently affixed to the top of the passive vents with solar flares should achieve this objective. The flares feature solar-powered continuous ignition and do not require an external power source. In addition, the flares will increase negative pressure at the gas vents, which should establish a more consistent inward gradient for landfill gas and better control its movement away from the waste mass. The augmentation of the gas vents with solar-powered flares is anticipated to accelerate attenuation of gas concentrations in the gas monitoring probes to below the regulatory limit. The flares should arrive at the site in May and be scheduled for installation shortly thereafter. Please contact me at (303) 914-1445 should you have questions about this report. Sincerely, On behalf of North Weld Landfill Tom Schweitzer Engineering Manager cc: Kim Ogle, WCDPS, w/o enc. Bill Hedberg, NWLF 2400 West Union Avenue Englewood,CO 80110 303-914-1445(Phone) WASTE MANAGEMENTS 303-914-9937 (Fax) RECEIVED AIM 28 '1nf7 April 23, 2012 Weld County Planning Department GREELEY OFFICE Ms. Cindy Beeler, Environmental Engineer Office of Enforcement, Compliance and Environmental Justice Mail Code 8 ENF-T U.S. Environmental Protection Agency, Region VIII 1595 Wynkoop Street Denver, CO 80202-1129 Certified Mail 7003 3110 0005 2391 8663 SUBJECT: NORTH WELD LANDFILL (NWLF) TITLE V OPERATING PERMIT NUMBER 97OPWE181 2012 ANNUAL COMPLIANCE CERTIFICATION REPORT Dear Ms. Beeler: In accordance with the NWLF Title V Operating Permit#97OPWE181, enclosed is the 2012 Annual Compliance Certification Report, which covers the period April 1, 2011 through March 31, 2012. Should you have any questions regarding this report, please contact me at (303) 914-1445 or Mr. Bill Hedberg at (970) 686-2800 ext. 23. Sincerely, Tom Schweitzer Engineer Manager Attachment cc: Douglas Ikenberry, CDPHE, w/o enc. Troy Swain, WCDPHE, w/o enc. Kim Ogle, WCDPS, w/0 enc. Dana Podell, CDPHE, w/o enc. Bruce Clabaugh, WMC, w/o enc. Bill Hedberg, WMC, w/enc. Co\-,ver\wrueS&V cAn a01 - D I9 r'I 5 1- , -PL ()-Tl 1 2400 West Union Avenue Englewood, CO 80110 ., 303-914.1445(Phone) WASTE MANAGEMENT 303-914-9937 (Fax) RECEIVED APR s gym, April 23, 2012 2 Wei, :.partinont Ms. Dana Podell Colorado Department of Public Health and Environment Air Pollution Control Division APCD-SS-B1 4300 Cherry Creek Drive South Denver, CO 80246-1530 Certified Mail 7003 3110 0005 2391 8656 SUBJECT: NORTH WELD LANDFILL (NWLF) TITLE V OPERATING PERMIT#97OPWE181 ANNUAL COMPLIANCE CERTIFICATION REPORT SEMI-ANNUAL MONITORING REPORTS Dear Ms. Podell: In accordance with the NWSL Title V Operating Permit # 97OPWE181, attached are the following reports. • Annual Compliance Certification Report(Period: 04/01/11 - 03/31/12) • Semi-annual Monitoring and Deviation Report, Parts I, II, and III (Period: 10/01/11 - 03/31/12). Part II of the Monitoring and Deviation Report shows there were no permit deviations, upsets, or emergency conditions that occurred during this reporting period and appears blank. Should you have any questions regarding these reports, please contact me at(303) 914-1445 or Mr. Bill Hedberg at (970) 686-2800 ext. 23. Sincerely, Tom Schweitzer Engineering Manager Attachments cc: Douglas Ikenberry, CDPHE, w/enc. Troy Swain, WCDPHE, w/enc. Kim Ogle, WCDPS, w/o enc. Bill Hedberg, WMC, w/enc. Bruce Clabaugh, WMC, w/enc. RECEIVED JUN 01 'nl? Weld County Planning Department GREELEY OFFICE Aq� opal-pas AquA�r 7430 E.Caley Avenue,Suite 310° Centennial,CO 80111 °Phone(303) 771-9150° Fax(303) 771-8776 May 24,2012 123330 Mr. Jeny Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver,Colorado 80246-1530 Mr.Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Colorado 80631 RE: North Weld Landfill,Ault, Colorado First Half 2012 Groundwater Monitoring Report Dear Mr.Henderson and Mr. Swain: On behalf of Waste Management Disposal Services of Colorado,Inc.,AquAeTer, Inc. submits the first half 2012 groundwater detection monitoring results for the North Weld Landfill (NWLF) in Ault, Colorado. Regular semi-annual detection groundwater monitoring was completed in March 2012. Enclosed is one copy of the report for CDPHE, one copy of the report for WCDPHE, and an electronic file containing laboratory analytical data for CDPHE. There were no volatile organic compound detections and no verified statistical exceedances during the first half 2012 event, and NWLF remains in detection monitoring in accordance with 6 CCR 1007-2, Part 1 —Regulations Pertaining to Solid Waste Sites and Facilities(revised March 30, 2011). In anticipation of including shallow well MW-9 in the groundwater monitoring system prior to landfilling in the vicinity as early as 2015, one event of background monitoring at this well was conducted in the 1H12. The monitoring results for well MW- 9 are included in this report. • 6mm 4.J—te- oela- !)/oZ°1 (A -l1-20/3_ p�U777 Mr.Jerry Henderson and Mr.Troy Swain 123330 May 24,2012 Page 2 If you have any questions pertaining to the groundwater detection monitoring program at NWLF, please contact Mr. Bill Hedberg at (970) 686-2800 or Mr. Tom Schweitzer at(303) 914-1445. Sincerely, AquAeTer, Inc. C Tenn Plute,E.I. Cathryn Stewart,P.G. Project Engineer Project Manager cc: Ms.Kim Ogle, WCDPS,w/o enc. Mr.Louis Bull, Waste Management,w/enc. Mr.Bill Hedberg, Waste Management,w/enc. Mr.Brad Pollock, Waste Management,w/o enc. Mr.Tom Schweitzer,Waste Management, w/enc. 1861 - 2011 DEPARTMENT OF PLANNING SERVICES PLANNING DIVISION 1555 N. 17TH AVENUE GREELEY, CO 80631 W E L DEC O U N T Y 970-353-6100 EXT 3549 FAX 970-304-6498 koglecaweld.co.us June 26, 2012 Mr. Bill Hedberg Waste Management North Weld Landfill 40000 County Road 25 Ault, Colorado 80610 Mr. Tom Schweitzer Waste Management North Weld Landfill 40000 County Road 25 Ault, Colorado 80610 Subject: USR-895 - North Weld Landfill Disposal Footprint Dear Messrs. Hedberg and Schweitzer: The Department of Planning Services has reviewed your letter dated June 21, 2012 concerning the disposal footprint expansion at the North Weld Landfill, land use permit number USR-895. The Department of Planning Services has determined that the expansion of three acres to the disposal area [from 119 acres to 122 acres] at the North Weld Landfill due to technological advancement in engineering mapping does not constitute a requirement to amendment the existing permit. This office accepts the 122 acre disposal footprint within the 170 acre landfill site as the permitted area with the prescribed setbacks from the property boundary to the limit of waste. Further, the maximum allowable height of 5210 feet above mean sea level must be maintained as stipulated in the Development Standards for USR-895. At this juncture, no further action will be required by Waste Management. If this office may be of further assistance, please contact us at 970.353.6100 extension 3540. (Sincerely, reKi gle Planning Services ec: T.Swain,Environmental Health D. Ikenberry,CDPHE E.Gesick,Clerk to the Board File: USR-895 C`UY,ti, ka.ICW a?O7 2 D/a9 7-9- 2oia- to 0777 VIM North Weld Landfill 40,000 Weld County Road 25 Ault,CO 80610 WASTE MANAGEMENT 970-686-2800(Phone) 970-686-1031 (Fax) June 21, 2012 Mr. Troy E. Swain Weld County Department of Public Health & Environment 1555 N. 17th Avenue Greeley, CO 80631 Mr. Kim Ogle Weld County Department of Planning Services 1555 N. 17"'Avenue Greeley, CO 80631 RE: North Weld Landfill Disposal Footprint Dear Mr. Swain and Mr. Ogle: Condition 1 of the 1990 Development Standards for North Weld Landfill (NWLF)indicates that 119 acres of the 170-acre parcel shall be used for waste filling. A recent evaluation of the approved facility development plans shows the disposal area to be about 122 acres, or a difference of approximately three acres from the acreage Indicated in the original Development Standards. The 119-acre disposal area was based on an old base grade map prepared by Industrial Compliance(IC)dated October 17, 1989. Subsequently, as the technology of surveying and computer aided design and drafting (CADD) has improved, NWLF contracted with Rust Environment and Infrastructure(REI)to prepare CADD drawings for the site, including base/final grades(from the IC 1989 plans), phasing and drainage plans, and design details of the liner, leachate collection system and final cover components. REI's work resulted in the development plans currently utilized at the site titled, "Site Development Plan for Waste Management Disposal Services of Colorado, Inc., North Weld Sanitary Landfill, Weld County Colorado,'dated January 1996 and later revised November 13, 1997. This Plan was included in the approved NWLF Updated Design and Operations Plan, as revised November 1997. We are uncertain as to why the acreage of the disposal footprint changed between IC's drawings and REI's enhanced plans, but surmise it may have occurred during the digital conversion of the old IC drawings. For reasons outlined below, the 122 acres represents a more technically accurate measurement of the facility's waste disposal footprint. • The maximum allowable height of the landfill of 5210 feet above mean sea level has not changed from the maximum elevation prescribed in the Development Standards. • The 122-acre footprint complies with prescribed setbacks from the property boundary to the limit of waste, as amended. 2012-1713 Mr. Troy E. Swain and Mr. Kim Ogle June 21, 2012 Page 2 • The total waste disposal capacity is currently calculated at approximately 15,280,000 CY (all volume calculations include daily and intermediate cover). From the approved NWLF Updated Design and Operations Plan, as amended, the disposal capacity for the site is 15,116,422 CY. Given the size of the site,we believe the insignificant 1% difference may largely be the result of increasing accuracy of volumetric calculations. We do not believe that updating the original footprint acreage in the 1990 Development Standard, Condition#1 to be consistent with the approved Site Development Plan represents a significant impact to site operations and design, and continues to comply with maximum fill height and setback requirements of the Development Standards, as amended. Accordingly, we are filing this adjustment as a minor change with the WCDPS and WCDPHE in accordance with Condition #34 of the CD Development Standards. Please do not hesitate to contact either of the undersigned should you have questions or need additional information. Sincerely, t ' Bill Hedberg, Tom Schweitzer, Sr. District Manager Engineering Manager 970-686-2800 x.23 303-914-1445 Cc: Mr. Doug Ikenberry, CDPHE e c.'szPy5 2400 West Union Avenue Englewood, CO 80110 .. , 303-914-1445(Phone) WASTE MANAGEMENT 866.442-0285(Fax) RECEIVED JUL 18 21)1? July 13, 2012 Weld County Planning Department GREELEY OFFICE Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 Xi ti 4300 Cherry Creek Drive South m c m Denver, CO 80246-1530 C> 0 30 X7'9 Mr. Troy Swain ' `—"o Weld County Department of Public Health and Environment D (pc 1555 N. 17th Avenue Greeley, CO 80631 a c� r SUBJECT: NORTH WELD LANDFILL SECOND QUARTER 2012 LANDFILL GAS (Methane) MONITORING REPORT Dear Mr. Henderson and Mr. Swain: Enclosed for your information is the Second Quarter 2012 Gas Monitoring Report for North Weld Landfill (NWLF). AquAeTer performed the monitoring of the subsurface and facility structures for methane migration in accordance with 6 CCR 1007-2 on June 18, 2012. The report contains monitoring results from the Phase 1 and 2 perimeter soil gas probes GP-06, GP-07, GP-10 through GP-20, structure probes GP-01 and GP-02, inside the shop and office, and confined spaces in the vicinity of the western boundary of the site. A map showing the gas probe locations, the scale house and maintenance shop is included as Figure 1. Section 2.3.1 of the Regulations Pertaining to Solid Waste Sites and Facilities, 6 CCR 1007-2, Part 1 (Regulations) requires that the percent of methane (explosive gas) in air (v/v) shall not exceed (A) 25% of the lower explosive limit (LEL) (i.e., 1.25% methane v/v) within facility structures, and (B) the LEL (i.e., greater than 5% methane v/v) at the facility boundary. During this monitoring event, methane was detected in structure probe GP-01 at 27.9% v/v, perimeter probe GP-06 at 7.8% v/v and perimeter probe GP-10 at 17.3% v/v. Although below regulatory limits, methane was also detected in probe GP-16 at 0.5% v/v. Methane was not detected in any of the other probes, shop, office or confined spaces during the first Quarter 2012 monitoring event. The facility currently operates under an approved gas remediation plan prepared in response to previous elevated methane concentrations in structure probe GP-01 and perimeter probes GP-10 and GP-11. The plan includes monthly monitoring of these probes and utility corridor access points along WCR 25. Beginning in February 2012, the facility also began monthly monitoring of eerarvu..41/cn(c -t,� g-2O -c20/ea_ ,270/07- aaq PL0"7 7 7 Letter Jerry Henderson and Troy Swain July 13, 2012 Page 2 GP-06. Included in Attachment 1 are the January and February 2012 monthly reports. A summary of the monitoring results for these monthly events is provided in the following table. Percent (%) CH4 v/v Monitoring Probe April 2012 May 2012 GP-01 13.9 25.2 GP-06 0.0 3.4 GP-10 1.2 12.6 GP-11 0.0 0.0 Methane was not detected in the utility corridor access points or facility structures during the monthly monitoring. The approved remediation plan also included the installation and operation of passive gas vents constructed within waste along the western limit of the disposal area. As stated in the plan, the passive vents, which were installed in December 2009, may require one or more years to show consistent reduction in methane levels at perimeter probes GP-10 and GP-11 and structure probe GP-01. Until methane levels are below the regulatory threshold for three consecutive monthly events, monthly monitoring will continue to be performed. As previously indicated, GP-06 was added to the monthly monitoring program commencing in February 2012. Continuous methane monitors are in operation within the facility maintenance building, office and gatehouse and no methane detections have been observed. We have been evaluating options to augment the performance of the existing in waste passive gas vents in order to increase their radius of influence in the southwest corner of the disposal area. We have determined that replacing the wind turbines presently affixed to the top of the passive vents with solar flares should achieve this objective. The flares feature solar-powered continuous ignition and do not require an external power source. In addition, the flares will increase negative pressure at the gas vents, which should establish a more consistent inward gradient for landfill gas and better control its movement away from the waste mass. The augmentation of the gas vents with solar-powered flares is anticipated to accelerate attenuation of gas concentrations in the gas monitoring probes to below the regulatory limit. We are currently in the process of confirming whether any emissions permitting of the flares is required prior to their installation. Please contact me at (303) 914-1445 should you have questions about this report. Sincerely, On behalf of North Weld Landfill Tom Schweitzer Engineering Manager cc: Kim Ogle, WCDPS, w/o enc. Bill Hedberg, NWLF RECEIVED OCT 1 1 1147 JVeld Ccurat; ... .g Department GREELEY OFFICE •,\ 2400 West Union Avenue ) Englewood,CO 80110 *:< . 303-914-1445(Phone) WASTE MANAGEMENT 866-442-0285(Fax) October 8, 2012 Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, CO 80246-1530 Mr. Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley. CO 80631 SUBJECT: NORTH WELD LANDFILL THIRD QUARTER 2012 LANDFILL GAS (Methane) MONITORING REPORT Dear Mr. Henderson and Mr. Swain: Enclosed for your information is the Third Quarter 2012 Gas Monitoring Report for North Weld Landfill (NWLF). AquAeTer performed the monitoring of the subsurface and facility structures for methane migration in accordance with 6 CCR 1007-2 on September 13, 2012. The report contains monitoring results from the Phase 1 and 2 perimeter soil gas probes GP-06, GP-07, GP- 10 through GP-20, structure probes GP-01 and GP-02, inside the shop and office, and confined spaces in the vicinity of the western boundary of the site. A map showing the gas probe locations, the scale house and maintenance shop is included as Figure 1. Section 2.3.1 of the Regulations Pertaining to Solid Waste Sites and Facilities, 6 CCR 1007-2, Part 1 (Regulations) requires that the percent of methane (explosive gas) in air (v/v) shall not exceed (A) 25% of the lower explosive limit (LEL) (i.e., 1.25% methane v/v) within facility structures, and (B) the LEL (i.e., greater than 5% methane v/v) at the facility boundary. During this monitoring event, methane was detected in structure probe GP-01 at 29.1% vlv. Methane was not detected in any of the other probes. shop, office or confined spaces during this monitoring event. The facility currently operates under an approved gas remediation plan prepared in response to previous elevated methane concentrations in structure probe GP-01 and perimeter probes GP-10 and GP-11. The plan includes monthly monitoring of these probes and utility corridor access points along WCR 25. Beginning in February 2012, the facility also began monthly monitoring of GP-06. Included in Attachment 1 are the July and August 2012 monthly reports. A summary of the monitoring results for these monthly events is provided in the following table. CL��L1114 )�C1 L:/)- �/'�L( lb --17-<;z� j777 Letter Jerry Henderson and Troy Swain October 8, 2012 Page 2 Percent (%)CH4 v/v Monitoring Probe July 2012 August 2012 GP-01 28.8 28.6 GP-06 8.4 0.2 GP-10 10.8 0.0 GP-11 0.0 0.0 Methane was not detected in the utility corridor access points or facility structures during the monthly monitoring. The approved remediation plan also included the installation and operation of passive gas vents constructed within waste along the western limit of the disposal area. As stated in the plan, the passive vents, which were installed in December 2009, may require one or more years to show consistent reduction in methane levels at perimeter probes GP-10 and GP-11 and structure probe GP-01. Until methane levels are below the regulatory threshold for three consecutive monthly events, monthly monitoring will continue to be performed. As previously indicated, GP-06 was added to the monthly monitoring program commencing in February 2012. Continuous methane monitors are in operation within the facility maintenance building, office and gatehouse and no methane detections have been observed. We have been evaluating options to augment the performance of the existing in waste passive gas vents in order to increase their radius of influence in the southwest corner of the disposal area. We have determined that replacing the wind turbines presently affixed to the top of the passive vents with solar flares should achieve this objective. The flares feature solar-powered continuous ignition and do not require an external power source. In addition. the flares will increase negative pressure at the gas vents, which should establish a more consistent inward gradient for landfill gas and better control its movement away from the waste mass. The augmentation of the gas vents with solar-powered flares is anticipated to accelerate attenuation of gas concentrations in the gas monitoring probes to below the regulatory limit. The first two solar flares were installed on the two southernmost passive vents on August 23. Among the seven passive vents installed at the site, these two vents are closest to the gas probes that have registered elevated methane readings. We are arranging to install solar flares on the remaining five passive vents. Please contact me at (303) 914-1445 should you have questions about this report. Sincerely. On behalf of North Weld Landfill Tom Schweitzer Engineer cc: Kim Ogle, WCDPS, w/o enc. Bill Hedberg, NWLF STATE OF COLORADO John W. Hickenlooper, Governor Christopher E. Urbina, MD, MPH .c�oF/\1Rye Executive Director and Chief Medical Officer ti�� So3; Dedicated to protecting and improving the health and environment of the people of Colorado v*- Qa h5, . 4300 Cherry Creek Dr. S. Laboratory Services Division RECEIVED 's r x Denver, Colorado 80246-1530 8100 Lowry Blvd. RECEIVED Phone(303)692-2000 Denver, Colorado 80230-6928 Colorado Department Located in Glendale,Colorado (303)692-3090 of Public Health http://www.cdphe.slate.co.us and Environment October 9, 2012 WELD COUNTY COMMISSIONERS Mr. Torn Schweitzer 2400 West Union Ave Englewood, CO 80610 RE: 2012 Financial Assurance Review Waste Management North Weld Sanitary Landfill Dear Mr. Schweitzer: The Solid Waste Unit of the Colorado Department of Public Health and Environment (the Department) has conducted a review of the Financial Assurance compliance for Waste Management's North Weld Sanitary Landfill. The Financial Assurance Submittal was reviewed for compliance with Section 1.8 of the Regulations Pertaining to Solid Waste Sites and Facilities, 6 CCR 1007-2 (the Regulations). As a result from the Department's review and analysis, the Department herby approves Waste Management's 2012 Financial Assurance mechanism. The Department received Revised Cost Estimates for the above mentioned facility and correspondence for the review will be sent separately from the Solid Waste staff assigned to the facility. The Department is authorized to bill for its financial assurance review pursuant to Section 1.7 of the Regulations, and an invoice will be transmitted under separate cover. If you have any questions regarding this letter please contact Enrique Martinez at (303) 691-4054 or by email at em-ique.martinethlistate.co.us. Sincerely, Enrique A. Martinez Financial Assurance and Data Management Unit Solid and Hazardous Waste Program Hazardous Materials and Waste Management Division cc: SW/WLD/NWC/1.3 Weld County Commissioners ecc: Ikenberry, Doug— CDPHE Smith, Cindy— CDPHE O7 /a `C/ / /u e.arc74-9 /0V/,--1 • PL C 727 RECEIVED .;. OCT 30 ZO1L 2400 West Union Avenue pep�rtment Englewood, CO 80110 Weld County ri 303-914-1445(Phone) WASTE MANAGEMENT opccl _( Q�FIC- 866-442-0285(Fax) October 25, 2012 Ms. Dana Podell Colorado Department of Public Health and Environment Air Pollution Control Division APCD-SS-B1 4300 Cherry Creek Drive South Denver, CO 80246-1530 SENT UPS OVERNIGHT SUBJECT: NORTH WELD SANITARY LANDFILL (NWSL) TITLE V OPERATING PERMIT# 97OPWE181 2012 SEMI-ANNUAL MONITORING REPORTS Dear Ms. Podell: In accordance with the NWSL Title V Operating Permit # 97OPWE181, attached are the following reports covering the monitoring period of April 1, 2012 - September 30, 2012. • Monitoring and Permit Deviation Report, Part I • Monitoring and Permit Deviation Report, Part III Part II of the Monitoring and Permit Deviation Report was not completed because there were no permit deviations, upsets or emergency conditions that occurred during this reporting period. Should you have any questions regarding these reports, please contact me at (303) 914-1445 or Bill Hedberg at (970) 686-2800 ext. 23. Sincerely, Tom Schweitzer Engineer /attachments cc: Douglas Ikenberry, CDPHE, w/enc. Troy Swain, WCDPHE, w/enc. Kim Ogle, WCDPS, w/enc. Bill Hedberg, NWSL Bruce Clabaugh, WMC Lidp rui,ucr,i (Y) / 10 '77 7 1 Air Pollution Control Division Colorado Operating Permit Monitoring and Permit Deviation Report— Part I 1. Following is the required format for the Monitoring and Permit Deviation report to be submitted to the Division on a semi-annual basis unless otherwise noted in the permit. The Table below must be completed for all equipment or processes for which specific Operating Permit terms exist. 2. Part II of the Appendix B shows the format and information the Division will require for describing periods of monitoring and permit deviations, or upset or emergency conditions as indicated in the Table below. One Part II Form must be completed for each Deviation. Previously submitted reports (e.g. EERS or Upsets) may be referenced and the form need not be filled out in its entirety. FACILITY NAME: Waste Management Disposal Services of Colorado, Inc. -North Weld Sanitary Landfill OPERATING PERMIT NO: 97OPWEP181 REPORTING PERIOD: 4/01/12-9/30/12 (see first page of the permit for specific reporting period and dates) Upset/Emergency Operating Permit Unit Unit Description Deviations noted Deviation Code2 Condition Reported ID During Period?' Du .•:Period? YES NO YES NO E001 Landfill Gas Generation X X E002 Fugitive Particulate X X Emissions General Conditions X X Insignificant Activities X X ' See previous discussion regarding what is considered to be a deviation. Determination of whether or not a deviation has occurred shall be based on a reasonable inquiry using readily available information. 2 Use the following entries,as appropriate 1= Standard: When the requirement is an emission limit or standard 2= Process: When the requirement is a production/process limit 3= Monitor: When the requirement is monitoring 4= Test: When the requirement is testing 5= Maintenance: When required maintenance is not performed 6= Record: When the requirement is recordkeeping 7= Report: When the requirement is reporting 8= CAM: A situation in which an excursion or exceedance as defined in 40CFR Part 64 (the Compliance Assurance Monitoring(CAM)Rule)has occurred. 9= Other: When the deviation is not covered by any of the above categories C:\Air\NWLF\NWLF MPDR 2112012.doc Air Pollution Control Division Colorado Operating Permit Monitoring and Permit Deviation Report— Part II FACILITY NAME: Waste Management Disposal Services of Colorado, Inc. -North Weld Sanitary Landfill OPERATING PERMIT NO: 97OPWEP181 REPORTING PERIOD: 04/01/12-09/30/12 (see first page of the permit for specific reporting period and dates) Is the deviation being claimed as an: Emergency Upset N/A (For NSPS/MACT)Did the deviation occur during: Startup Shutdown Malfunction Normal Operation OPERATING PERMIT UNIT IDENTIFICATION: Operating Permit Condition Number Citation Explanation of Period of Deviation Duration(start/stop date&time) Action Taken to Correct the Problem Measures Taken to Prevent a Reoccurrence of the Problem Dates of Upsets/Emergencies Reported(if applicable) Deviation Code Division Code QA: C:\Air\NWLFINWLF MPDR 2t12012.doc Air Pollution Control Division Colorado Operating Permit Monitoring and Permit Deviation Report— Part III SOURCE NAME: Waste Management Disposal Services of Colorado, Inc. -North Weld Sanitary Landfill FACILITY IDENTIFICATION NUMBER 1230209 PERMIT NUMBER: 97OPWEP181 REPORTING PERIOD: 4/01/12-09/30/12 (see first page of permit for specific reporting period and dates) All information for the Title V Semi-Annual Deviation Reports must be certified by a responsible official. The responsible official signing this certification must be pre-approved by the Division in accordance with Colorado Regulation No. 3, Part A, Section I.B.38. This signed certification document must be packaged with the documents being submitted. STATEMENT OF COMPLETENESS I have reviewed the information being submitted in its entirety and, based on information and belief formed after reasonable inquiry; I certify that the statements and information contained in this submittal are true, accurate and complete. Please note that the Colorado Statues state that any person who knowingly, as defined in Sub- Section 18-1-501(6), C.R.S., makes false material statement, representation, or certification in this document is guilty of a misdemeanor and may be punished in accordance with the provisions of Sub-Section 25-7122.1, C.R.S. Bruce Clabaugh Environmental Protection Manager Printed or Typed Name Title /. ,lEu Z. , Signature of Responsible Official Date Signed Note: Deviation reports shall be submitted to the Division at the address given in Appendix D of this permit. No copies need be sent to the U.S.EPA. C:\Air\NWLF\NWLF MPDR 2112012.dos RECEIVED NOV 2 ,'. 9019 Weld County nu,y,,.o Department GREELEY OFFICE Aq o timizin ever pv,.�,,,,,,��.�,... ,.,,..�,,.�,��,g 7430 East Caley Avenue,Suite 310♦ Centennial,CO 80111 • Phone(303)771-9150♦Fax(303)771-8776 November 26, 2012 123330 Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, Colorado 80246-1530 Mr. Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Colorado 80631 Re: North Weld Landfill, Ault, Colorado—Second Half 2012 Groundwater Monitoring 14-Day Notification of Statistically Significant Increase Above Background (SSI) - Alkalinity at MW-4 Dear Mr. Henderson and Mr. Swain: In compliance with Colorado Regulations Pertaining to Solid Waste Disposal Sites and Facilities, 6 CCR 1007-2 (Solid Waste Regulations), Appendix B (4)(C)(1), AquAeTer, Inc., on behalf of Waste Management Disposal Services of Colorado,Inc.(WMDSC),is providing 14-day notification of a confirmed statistically significant increase above background (SSIs) for alkalinity at down- gradient well MW-4 at the North Weld Landfill (NWLF). In accordance with 6 CCR 1007-2 Appendix B(4)(C)(1),appropriate documentation has been placed in the facility operating record by copy of this letter, indicating that alkalinity at well MW-4 is a confirmed SSI. Appropriate data quality control checks were completed, including verification of proper field sampling protocol; proper implementation of laboratory methods;acceptable cation/anion balance;and time-equivalent water level and hydraulic gradient. The alkalinity SSI is for CUSUM; the actual reported result is below the statistical limit. The CUSUM SSI for alkalinity in the second half 2012(2H 12)results is interpreted to be the result of natural groundwater quality variability. A site map showing the locations of down-gradient well MW-4, the closest leachate sump, Sump-1, and up-gradient well MW-12 is included as Figure 1. SSI in the Second Half 2012 —Alkalinity at Well MW-4 In the First Half 2012 Groundwater Monitoring Report (May 2012), the reported concentration at well MW-4 for alkalinity(400 mg/L) was below the control limit(424.74 mg/L),but the CUSUM CcYYu plan/Cb-Ju /;Z-.3 .„2c7z Mr. Jerry Henderson and Mr. Troy Swain 123330 November 26, 2012 Page 2 (426.76 mg/L) was slightly above the control limit. As a result of this initial CUSUM exceedance, the background time window at well MW-4 was not updated on the regular two-year schedule to include the first half 2012(1H12)12)results. Verification re-sampling for alkalinity at well MW-4 was completed as part of the 2H12 monitoring event in September 2012. The reported 2H12 concentration for alkalinity (410 mg/L) remained below the control limit (424.74 mg/L), but the CUSUM value(436.76 mg/L)remained above the control limit. Therefore,this alkalinity CUSUM exceedance is identified as a SSI. The alkalinity data from the 2012 sampling events are summarized below. Statistical Summary for Alkalinity at Well MW-4 Detection Concentration Control Limit CUSUM Statistical Exceedance Event Detected(mg/L) (mg/L) (mg/L) 1H12 400 424.74 426.76 Initialexceedance 21412 410 424.74 436.76 SSI Alternative Source Demonstration for Alkalinity at Well MW-4 In accordance with requirements of 6 CCR 1007-2,this ASD has been prepared to demonstrate that the alkalinity SSI at well MW-4 is not the result of a landfill leachate release. Specifically, as allowed in Appendix B4(C)(3)of the Solid Waste Regulations,a demonstration can be made to show that the SSI at well MW-4 is caused by an alternative source(e.g., natural variation in groundwater quality)and that no further action should be required other than to continue detection monitoring at the well. If the alkalinity ASD is deemed acceptable by CDPHE,the MW-4 background data set will be updated and a finding of"no verified exceedance" will be reported. The cause of the confirmed statistical exceedance for alkalinity at well MW-4 is natural water- quality variability. The basis for this determination is provided below. Time-Series Plots (Alkalinity at Up-Gradient Well MW-12 and Down-Gradient Well MW-4) Time-series plots are helpful in groundwater data evaluation by providing a visual depiction of concentration changes over time. A time-series plot was prepared using data from down-gradient well MW-4 and up-gradient well MW-12, as shown in Figure 2. The time-series plot shows consistent, stable alkalinity concentrations in up-gradient well MW-12 since 1994,with an average concentration of approximately 524 mg/L. The plot also shows consistent, stable alkalinity concentrations in down-gradient well MW-4 since 1994, with slightly higher alkalinity concentrations observed since approximately 2009. The average alkalinity concentration at well MW-4 is lower than in up-gradient well MW-12 at approximately 377 mg/L. Mr. Jerry Henderson and Mr. Troy Swain 123330 November 26, 2012 Page 3 VOC Detections VOCs are excellent indicators of landfill impacts to groundwater as they typically are present in leachate, are mobile in groundwater systems, and typically are not naturally-occurring in groundwater. Leachate sump Sump-1 is hydraulically up-gradient of well MW-4 and contained sampleable leachate in 2009. VOCs were detected in the 2009 leachate sample where the maximum concentration of detected VOCs was 67 micrograms per liter(µg/L)for acetone. There have been no verified VOC detections in groundwater at well MW-4 (1994 through 2012). If leachate was the source of the alkalinity SSI at well MW-4,the detection of one or more of the VOCs detected in the leachate would be expected. Historical Major Ion Review Figures 3 and 4 are Stiff and Piper diagrams depicting representative groundwater data for well MW- 4 from the first sampling events in 1994 until the present, and November 2009 leachate data. Stiff diagram depictions of major ion chemistry in water are constructed by extending three parallel horizontal axes on each side of a vertical zero axis. Concentrations of four cations(Na+K,Ca,and Mg) are plotted to the left of zero. Concentrations of four anions (Cl, HCO3 + CO3, and SO4) are plotted to the right of zero. The ions are plotted in the same sequence and are presented in units of concentrations of milliequivalents per liter(meq/L). The width of the pattern is an indication of total ionic content. The Stiff patterns provide a relatively distinctive method of visually depicting differences or similarities in water chemistry. Piper trilinear diagrams are in the form of two triangles bracketing a diamond-shaped plotting field, as used by J.D. Hem(USGS, Water-Supply Paper 2254, 1985). Each vertex represents 100 percent of a particular ion or group of ions. The composition of cations is indicated by a point in the cation triangle, and the composition of anions by a point in the anion triangle. The coordinates at each point add to 100 percent. Anions and cations are combined to plot in the diamond-shaped field. Trilinear diagrams aid in data evaluation by providing visual depictions of trends or comparison of water quality between wells or between wells and potential sources(e.g.,leachate or off-site source). The Stiff diagrams(Figure 3)show that the basic chemistry of groundwater at well MW-4 has been remarkably consistent over time. The similarity of diagram shapes, based on major ion concentrations, shows that groundwater quality at well MW-4 has remained stable with no significant change in major ion chemistry. The Stiff diagram shape showing the major ion chemistry of the leachate is distinctly different from those of groundwater samples from well MW-4. The shape differences are dictated by the significantly higher concentrations of sodium, potassium, magnesium, chloride, and bicarbonate in the leachate. Based on the Piper diagram (Figure 4), groundwater at well MW-4 is a calcium-bicarbonate type water. The Piper diagram also shows that groundwater at well MW-4 has been consistent over time (1994 to present) as evidenced by the tight clustering of the ion plots on the fields of the Piper diagram. Figure 4 also shows that the ion compositions of the leachate and groundwater plot in Mr. Jerry Henderson and Mr. Troy Swain 123330 November 26, 2012 Page 4 distinctly different parts of the diagram and leachate is not mixing with groundwater. The difference between groundwater and leachate chemistries depicted on the Piper diagram is consistent with the differences in the Stiff diagram shapes discussed above. These Stiff and Piper diagrams support the conclusion that the alkalinity exceedance is caused by natural variability in groundwater. Waste Not Placed Immediately Up-gradient of Well MW-4 The most compelling evidence that the alkalinity CUSUM exceedance is not landfill related is the fact that waste has not yet been placed in the area immediately up-gradient of well MW-4. As shown on Figure 1, MW-4 monitors the eastern portion of the landfill and the groundwater contour map shows that waste does not yet exist up-gradient of this well. Based on the groundwater chemistry data for well MW-4, WMDSC contends that the alkalinity CUSUM exceedances observed in 1H12 and 2H12 samples represent natural variation in the groundwater chemistry,and thus,are false positive detections. Evidence supporting the conclusion that the alkalinity CUSUM SSI at well MW-4 is not from the landfill includes: • Waste has not yet been placed in the area immediately up-gradient of well MW-4. • Alkalinity concentrations observed at down-gradient well MW-4 have been relatively consistent over the full period of monitoring. Similarly, natural up-gradient groundwater quality, specifically alkalinity concentrations observed at up-gradient well MW-12, has shown consistent concentrations over the period of monitoring. Alkalinity concentrations observed at down-gradient well MW-4 consistently have been less than those observed at up-gradient well MW-12. • Major ion chemistry observed at well MW-4 has remained remarkably stable with no significant change in groundwater chemistry from 1994 to the present. • Major ion chemistry of leachate at Sump-1 is distinctly different from that of groundwater samples from well MW-4, indicating that leachate is not mixing with groundwater. • No VOC detections have been observed at well MW-4. CUSUM typically is sensitive to small increases over background, especially when the variance in the background dataset is small and the natural variability of these groundwater parameters are not routinely incorporated into the background dataset. When some changes in natural background conditions occur and such changes are not incorporated into the background dataset, false positive detections typically occur with respect to the CUSUM (i.e., slight increases of CUSUM above the statistical limit even when actual concentration is below statistical limit). Thus,routine updating of Mr. Jerry Henderson and Mr. Troy Swain 123330 November 26, 2012 Page 5 background is important to maintain appropriate statistical power and CUSUM accuracy (i.e., minimizing false positive results). The background data set for inorganic parameters at well MW-4 last was updated following the 1H10 10 event. The background time window at well MW-4 was not updated on schedule(following the 1H12 event)because of the initial CUSUM exceedance for alkalinity in the 1H12. Because the CUSUM increase has been demonstrated to be natural variation in the groundwater chemistry and not landfill-related, background is proposed to be updated through the 1H12. WMDSC recommends that well MW-4 remain in detection monitoring based on the above data observations. Second Half 2012 Groundwater Monitoring Report An ASD will be included in the Second Half 2012 Groundwater Monitoring Report. The inclusion of the ASD in the semi-annual groundwater submittal is consistent with CDPHE's previous request to reduce the number of individual report submittals to the agency. WMDSC looks forward to approval of this ASD for alkalinity at well MW-4. If you have any questions regarding this notification, please feel free to contact either of the undersigned at (303) 771-9150 or Mr. Bill Hedberg at (970) 686-2800 or Mr. Tom Schweitzer at (303) 914-1445. Sincerely, AquAeTer, Inc. Cathryn Stewart, P.G. Stephen Wam ler P.E. Project Manager Technical Director cc: Mr. Kim Ogle, WCDPS Mr. Louis Bull, Waste Management Mr. Bill Hedberg, Waste Management Mr. Brad Pollock, Waste Management Mr. Tom Schweitzer, Waste Management Enclosures: Figure 1 Location of Groundwater Monitor Wells and Sump used in ASD Figure 2 Time Series Plot for Alkalinity at Wells MW-4 and MW-12 Figure 3 Stiff Diagrams for Well MW-4 and Sump-1 Figure 4 Piper Diagram for Well MW-4 and Sump-1 z2 —o w woQul, rc do i- „ to H o a N 0300 .c..,-_t 0 I c _Z=w« 8--'" q NO¢> g k'§ $ ^ W2o�d' 6.01- W i ".� r . d crozWW az� 'g6 a y: pp =4a¢i ioyo' 1' €' d - H E ol6 cr io90 E 4° as j E $ ¢1 g 5 o3WNzHon- F 3 p 6 123 g fi 3 gg $ g 6 $ Sib 6 6� :'c B i _ e : 3 C u a zu 3 < $ XI i -, y l 2 I 11 I II �I 4 I i 0 11 MI6 N �p T)\:".\\\\\\I h g , 'I I I7. • r \ I1 ,li,41 .‘.II 4.21.1 1 IY t ° I , 1 \' I // 3 f N-N.:\ t s e et 22 1 \\ i {N il/t 4 to t � t ra a ' t �, . 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Fax (303) 771-8776 November 28, 2012 R E-8 JJVF D C ^?i9 Mr. Jerry Henderson Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, Colorado 80246-1530 Mr. Troy Swain Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Colorado 80631 RE: North Weld Landfill, Ault, Colorado Second Half 2012 Groundwater Monitoring Report Dear Mr. Henderson and Mr. Swain: On behalf of Waste Management Disposal Services of Colorado, Inc., AquAeTer, Inc. submits the second half 2012 groundwater detection monitoring results for the North Weld Landfill (NWLF) in Ault, Colorado. Regular semi-annual detection groundwater monitoring was completed in September 2012. Enclosed is one copy of the report for CDPHE, one copy of the report for WCDPHE, and an electronic file containing laboratory analytical data for CDPHE. In anticipation of including shallow well MW-9 in the groundwater monitoring system prior to landfilling in the vicinity as early as 2015, one event of background monitoring at this well was conducted in the second half 2012. The monitoring results for well MW-9 are included in this report. NWLF remains in detection monitoring in accordance with 6 CCR 1007-2, Part 1 — Regulations Pertaining to Solid Waste Sites and Facilities (revised March 30, 2011). There were no volatile organic compound detections and no verified statistical exceedances during the second half 2012 event, with the exception of one statistically significant increase (SSI) above background in the second half 2012. An Alternative Source Demonstration (ASD) for alkalinity at well MW-4 is included in Section 5 of the report. jowl y»w1 k C0., 1 GYLs \2- ()OU,1.- GI ;��j a — tO- Mr.Jerry Henderson and Mr.Troy Swain 123330 November 28,2012 Page 2 If you have any questions pertaining to the groundwater detection monitoring program at NWLF, please contact Mr. Bill Hedberg at (970) 686-2800 or Mr. Tom Schweitzer at(303) 914-1445. Sincerely, AquAeTer, Inc. Terra Plute, E.I. Cathryn Stewart, P.G. Project Engineer Project Manager cc: Mr. Kim Ogle, WCDPS, w/o enc. Mr. Louis Bull, Waste Management, w/enc. Mr. Bill Hedberg, Waste Management, w/enc. Mr. Brad Pollock, Waste Management, w/o enc. Mr. Tom Schweitzer, Waste Management, w/enc. Hello