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HomeMy WebLinkAbout20043685.tiff • • 6 DEPARTMENT OF PUBLIC HEALTH & ENVIRONMENT 1555 N. 17th Avenue Greeley, CO 80631 WEBSITE: www.co.weld.co.us ADMINISTRATION: (970) 304-6410 immipes FAX: (970) 304-6412 PUBLIC HEALTH EDUCATION & NURSING: (970) 304-6420 FAX: (970) 304-6416 ENVIRONMENTAL HEALTH SERVICES: (970) 304-6415 COLORADO FAX: (970) 304-6411 December 14, 2004 Maureen A. Yaskanin Golder Associates, Inc. 44 Union Boulevard, Suite 300 Lakewood, CO 80228 Subject: Denver Regional Landfill (South) September 9, 2004, Request for Use of Alternative Daily Cover October 19, 2004, Request for approval of Container Storage on Stockpile Area February 25, 2001, Request for Larger Working Face Dear Ms. Yaskanin: The Weld County Department of Public Health and Environment (Weld County) has reviewed your September 9, 2004 request for approval of bottom ash, fly ash, and Argo Tunnel Water Treatment Facility sludge for use as alternative daily cover (ADC) material, and your October 19, 2004 request for approval of container storage on the soil stockpile area. The above requests would be used at the Denver Regional Landfill located at 1441 Weld County Road 6. In our review of your request of the above requested changes we consulted with the Weld County Department of Planning Services. In consultation with the Weld County Department of Planning Services, Planning Services will require an amendment to the existing permit to allow the use of coal ash or Argo Tunnel sludge as an ADC, container storage on the soil stockpile area, and a larger working face. Therefore, Weld County will not approve the above mentioned requests. Additionally, in a letter dated February 25, 2001, you requested a larger working face. The request was Cc to increase the length from 150 to 300 feet and a height from 10 to 20 feet. It is my understand that Planning Services also required an amendment to the existing permit to allow for the working face to increase to a length of 300 feet and a height of 20 feet. To my knowledge, this has not yet been resolved. aooti-31085 ?L0777 • • Ron Pickett December 15, 2004 Page 2 Should you have any questions regarding this letter you may contact Kim Ogle of the Department of Planning Services at (970) 353-6100, or myself at (970) 304-6415, extension 2220. Sincerely, Cindi Etcheverry E. H. Supervisor Environmental Health Services cc: Trevor Jiricek, Director, Environmental Health Services (via email) Doug Ikenberry, Colorado Department of Pubic Health and Environment Glen Mallory, Colorado Department of Public Health and Environment (via email) Lee Morrison, Weld County Attorneys Office (via email) Kim Ogle, Department of Planning Services (via email) Mark Adams, Waste Connections Ron Pickett, Denver Regional Landfill C:\Documents and Settings\kogle\Local Settings\Temporary Internet Files\OLK375\041219ADC request response.doc • • 6 DEPARTMENT OF PUBLIC HEALTH & ENVIRONMENT 1555 N. 1 7th Avenue fAt Greeley, CO 80631 WEBSITE: www.co.weld.co.us ADMINISTRATION: (970) 304-6410 FAX: (970) 304-6412 gpic PUBLIC HEALTH EDUCATION & NURSING: (970) 304-6420 FAX: (970) 304-6416 ENVIRONMENTAL HEALTH SERVICES: (970) 304-6415 COLORADO FAX: (970) 304-6411 December 14, 2004 Alan Scheere Bill Hedberg Waste Management Buffalo Ridge Landfill 7780 E. 96th Avenue 11655 Weld County Road 59 Henderson, CO 80640 Keenesburg, Colorado Subject: Buffalo Ridge Landfill —4th Quarter Inspection, 2004 Dear Mr. Scheere and Mr. Hedberg: On December 2, 2004, a routine inspection of the Buffalo Ridge Landfill was conducted. The landfill is located just north of Keenesburg, having the address of 11655 Weld County Road 59, in Weld County, Colorado. The purpose of the inspection was to inspect and assess the facility's compliance with the "Regulations Pertaining to Solid Waste Disposal Sites and Facilities" (the Regulations) as promulgated by the Solid Waste Disposal Sites and Facilities Act, Title 30, Article 20, part 1, C.R.S., as amended, and the Development Standards set forth in U.S.R.-895. On this date it was observed that the site was in substantial compliance with both the Regulations and U.S.R.-895. If you have any questions regarding this inspection, please contact me at 304-6415, extension 2220. Sincerely, Cindi Etcheverry Environmental Health Supervisor Environmental Health Services cc: Trevor Jiricek, Director, Weld County Environmental Health Services (via email) Doug lkenberry, Colorado Department of Public Health and Environment Lee Morrison, Weld County Attorneys Office (via email) Kim Ogle, Weld County Department of Planning Services (via email) C:\Documents and Settings\kogle\Local Settings\Temporary Internet Files\OLK375\041202insp.doc • • 5575 ETC Parkway, Suite 200, Englewood, Colorado 801 1 1-3016 Weld County Planning Department December 3, 2004 GREELEY (}FF GF DEC 2004 Mr. Douglas Ikenberry, P.E. Colorado Department of Public Health and Environment RECEIVED Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, Colorado 80246-1530 Re: Buffalo Ridge Landfill -First Semi-Annual 2004 Groundwater Monitoring 14-Day Notification of a Statistically Significant Increase and Alternative Source Demonstration Dear Mr. Ikenberry: In accordance with Colorado Regulations Pertaining to Solid Waste Disposal Sites and Telephone Facilities, 6 CCR 1007-2(B4)(C)(1), Earth Tech Inc. (Earth Tech) on behalf of the 303.694 6 6 6 o Buffalo Ridge Landfill (BRLF), is providing this 14-day notification of a confirmed statistically significant increase(SSI)over background of the Cumulative Sum(CUSUM) Facsimile for chloride at downgradient well MW04 and sodium at downgradient well MW06. Previous notification of this SSI was provided in the First Semi-Annual 2004 303•694•4410 Groundwater Sampling Report submitted on November 19,2004. In accordance with 6 CCR 1007-2(B4)(C), documentation has been placed in the facility operating record indicating that chloride in well MW04 and sodium in well MW06 have shown a confirmed statistical exceedance. In accordance with requirements of the 6 CCR 1007-2, (Regulations) Earth Tech is providing this submittal as a demonstration that the source of the statistically significant increases(SSIs)over background for chloride in well MW04 and sodium in well MW06 are not the result of a leachate release. Specifically,as allowed in Appendix B4(C)(3)of the Regulations,it is shown that SSIs at MW04 and MW06 are due to natural variation in groundwater quality, and that variable background conditions have not been adequately incorporated into background data,resulting in false positive detections for chloride and sodium. MW04 AND MW06 BACKGROUND DATA G The background window for statistical data at wells MW04 and MW06 includes groundwater data from the period of the fourth quarter 1994 to the second quarter 2002. However, due to a delay in site operations, no groundwater samples were collected during the years of 1999, 2000 and 2001. As a result of this delay, any variations in groundwater conditions during the three years of 1999-2002 were not captured in the background data set. til EAR T H `sim T ECH A Tyco Infrastructure Services Company • • Mr. D ouglas Ikenberry December 3, 2004 Page 2 Prior to the initiation of site disposal operations, sampling was resumed in the second quarter 2002 to update background and incorporate as much temporal variability as possible before initiation of detection monitoring statistics. Based on the initial statistical runs performed in DUMPStat by Dr.Robert Gibbons,statistically significant increasing groundwater trends were documented in predisposal data for several parameters including bicarbonate alkalinity,calcium,magnesium,nitrate,sodium,sulfate,and TOC. These results show that background conditions at the BRL are variable and that these temporal changes would need to be incorporated into background to help avoid statistical false positive detections. The initial DUMPStat runs were included in the report Statistical Methods for Ground-Water Monitoring at the Buffalo Ridge Landfill,prepared by Dr. Robert Gibbons in March 2003, and provided to the Colorado Department of Public Health and Environment (CDPHE) with the Second Semi-annual 2002 Groundwater Sampling Report dated March 26, 2003. ALTERNATIVE SOURCE DEMONSTRATION The following presents an Alternative Source Demonstration(ASD)for the recent SSIs seen in wells MW0 4 and MW06. This demonstration will include data related CUSUM calculations, a discussion about natural variability of groundwater quality, the lack of volatile organic compound (VOC) detections, and a comparison to leachate data. CUSUM Exceedances The calculation of CUSUM is routinely computed at BRL along with control limits in order to quantify both immediate and gradual trends in the data. As samples are collected,background values are used to calculate a standardized mean and a cumulative sum of deviation above that mean. Should a gradual change occur to background conditions, and that change not be properly incorporated into the background obvious problems in the form of false positives will occur with respectto the CUSUM. The cause of the false positive CUSUM exceedences reported herein is summarized as follows. The calculated CUSUM values for chloride in MW04 and sodium in MW06 immediately increased with the analysis of the first and second detection monitoring samples (in late 2002 and early 2003). However, it is emphasized that the actual detected concentrations were only slightly above the historical background average as shown on Figures 1 and 2. When increasing natural trends are not properly incorporated into the background dataset, CUSUM values can routinely result in false positive detections. These false positive detections occur when the overall variability in the background concentrations of these parameters is small, or natural trends are not properly incorporated into background. EARTH `. TECH AY CO INTERN �I ATIO`JAL LID COMPANY • • Mr. Douglas Ikenberry December 3, 2004 Page 3 When these conditions exist, CUSUM becomes very sensitive to small increases over background. For example, the results shown on Figures 1 and 2 indicate that actual results from 2002 to the present are only slightly above the historical average. Most importantly, although CUSUM slightly exceeds the statistical limit none of the actual results are above their statistical limit. Natural Variability The attached Figures 1 and 2 show the control charts for chloride in upgradient well MW03 and downgradient well MW04, and sodium in upgradient well MW03 and downgradient well MW06. These control charts demonstrate the sensitivity of CUSUM to natural trends and small increases over background both upgradient and downgradient of the landfill.Natural groundwater conditions both upgradient and downgradient of the landfill have changed enough to cause the observed CUSUM exceedances. These statistical exceedances are a clear demonstration of the natural variation in groundwater quality at the site,which should be immediately incorporated into the background dataset prior to the application of any future statistical evaluations. Additionally, as previously stated, initial statistical runs performed in DUMPStat by Dr. Robert Gibbons showed statistically significant increasing groundwater trends in predisposal data for several parameters including bicarbonate alkalinity, calcium, magnesium, nitrate, sodium, sulfate, and TOC. Again, this is a clear demonstration of the natural variation in background groundwater quality in and around BRLF. Also, as seen on Figures 3 and 4, since resuming groundwater monitoring in 2002, chloride and sodium concentrations in MW04 and MW06 have been consistent,as have concentrations of these parameters in upgradient well MW03. VOC Detections Volatile organic compounds (VOC) are excellent indicators of leachate impacts on groundwater as they are typically present in leachate at elevated concentrations, are mobile in groundwater systems,and are not typically found in unimpacted groundwater. The 2002, 2003 and 2004 analysis of BRLF leachate from the temporary sump shows various VOC detections in concentrations ranging from 280-7400 micrograms per liter (µg/1). To date,there have been no verified VOC detections in groundwater in any wells at BRLF. These data support the conclusion that there is no evidence of a leachate impact. EARTH `� TECH A NCO INTERNATIONAL LW COMPANY • • Mr. Douglas Ikenberry December 3, 2004 Page 4 Leachate Comparison The simplest Piper plots utilize two triangles—one for anions and one for cations. Each vertex represents 100 percent of a particular ion or group of ions. The composition of cations is indicated by a point plotted in the cation triangle, and the composition of anions by a point plotted in the anion triangle. The coordinates at each point add to 100 percent. Most trilinear diagrams are in the form of two triangles bracketing a diamond shaped plotting field, as first described by Piper (1944). Trilinear plots aid in data evaluations by providing a visual clarification of trends,or a comparison of differences in water quality between wells or wells and potential sources(e.g.,leachate,offsite source). Stiff diagrams are constructed by extending three parallel horizontal axes extending on each side of a vertical zero axis. Concentrations of four cations(Mg,Ca,and Na+K)are plotted,one on each axis to the left of zero,and likewise four anion(SO4,Cl,and HCO3+ HCO3) concentrations are plotted, one on each axis to the right of zero. The ions are always plotted in the same sequence and are presented in concentrations of milliequivalents per liter. The Stiff ff patternsprovide. . a relatively distinctive method of showing water composition differences or similarities. The width of the pattern is an approximate indication of total ionic content. Stiff diagrams aid in data evaluations by providing a visual clarification of trends,or a comparison of differences in water quality between wells or wells and potential sources (e.g., leachate, off-site source). Figure 5 and 6 show Stiff and Piper diagrams for groundwater from wells MW04 and MW06 before the commencement of disposal operations,from recent MW04 and MW06 data, and for recent leachate data. These plots are compared to determine changes in geochemical signature that could be attributable to a leachate impact. It can be seen in the diagrams that the groundwater in well MW04 and MW06 is not becoming more similar to leachate. There is no evidence of mixing. These data support the conclusion that there is no evidence of leachate impact. CONCLUSIONS AND RECOMMENDATIONS The groundwater quality information in this ASD,in accordance with the requirements of 6 CCR 1007-2, provides adequate demonstration that the source of the statistically significant increases (SSIs)over background for chloride in well MW04 and sodium in well MW06 are not from a leachate release. Specifically, as allowed in Appendix ]34(C)(3)of the Regulations,it is shown that the CUSUM SSIs at MW04 and MW06 are due to natural variation in groundwater quality,and that variable background conditions have not been adequately incorporated into background resulting in false positive detections for chloride and sodium. EARTH `• TECH A tljCO INTERNATIONAL IT:, CC\IpANY • • ivlr. Douglas Ikenberry December 3, 2004 Page 5 Once the ASD is approved by the CDPHE, the following recommendations will be administered at BRLF: 1. BRLF will continue with its detection monitoring program. 2. Update the statistical background window for wells MW04 and MW06 to properly incorporate these recent data. 3. Review the appropriateness of the current analyte list and the possibility for the removal of ineffective detection monitoring parameters in the attempt to reduce false positive detections. This review and any proposed reduced monitoring parameter list will not jeopardize the objective of the detection monitoring program (providing early warning of a potential leachate release). Earth Tech and BRLF request your approval of this ASD, and continuation of the detection monitoring program at BRLF. If you have any questions regarding this notice, please feel free to contact me at(303) 694-6660 or Alan Scheere at(720) 977-2107. Very truly yours, Earth Tech, Inc. • Randall Thom , .E. Project Engineer cc: Cindi Etcheverry, WCDPHE Alan Scheere, WM Kim Ogle, WCDPS Jack Epple, BRLF Lou Bull, WM Len Butler, WM 74930\product\BRL14day.doc EARTH `ff TECH A tgco INTERNATIONAL LTD COMPANY • • BRL [detwells] Analysis prepared on: 11/11/2004 FIGURE 1 Detect ■ Chloride for sample point MWO3 ND Normal Control Limit CUSUM • 50. Outlier E. 45. 40. Man. outlier e 35. M 30. '[/, Verify v G 25. /User Limit 20. �_-- •' Backgnd 10.L �I E ■ in ■ �" •■ ■ ■■ - II-- Samples. ® 5. 0. T CUSUM • • 94 95 96 97 98 99 00 01 02 03 04 05 Limit Year Graph 91 Detect ® Chloride for sample point MWO4 ND Normal Control Limit CUSUM 0 500. Outlier 450. 400. Man. outlier : 350. M 300. Verify - v G 250. - • User Limit 200L . { ■- 6 ■ ■ �r■+�■ •■ ■ U ■ n Backgnd 150. I g 100. Samples® ® 50. 0. I CUSUM • • 94 95 96 97 98 99 00 01 02 03 04 05 Limit Year Graph 92 Prepared by: Earth Tech 1 • • BRL [detwells] Analysis prepared on: 11/11/2004 FIGURE 2 Detect ■ Sodium-dissolved for sample point MWO3 ND Normal Control Limit CUSUM • 1000000. Outlier 900000. 800000. _11 Man. outlier 700000. - — ' Verify ,U 600000. /41 I-V G 500000. — .- I' User Limit 400000. o ;�. r • Backgnd 300000. '� 200000. -, Samples ■ ■ 100000. 0. - - CUSUM • • 94 95 96 97 98 99 00 01 02 03 04 05 Limit Year Graph 223 Detect ® Sodium-dissolved for sample point MWO6 ND Normal Control Limit CUSUM • 200000. Outlier 180000. . 160000. Man. outlier 140000. a • U 120000. Verify 4 _ G 100000. in ���� 'rte User Limit 80000. + • Backgnd 60000. 40000. Samples ® ® 20000. 0. CUSUM • • 94 95 96 97 98 99 00 01 02 03 04 05 Limit Year Graph 226 Prepared by: Earth Tech 1 • • BRL idetwells] Analysis prepared on: 12/2/2004 FIGURE 3 Detect ® Chloride for sample point MWO3 ND Man. outlier 20.0 18.0 ■ 16.0 ■ 14.0 ■__ M 12.0 - G 10.0 - / 8.0 -. L 6.0 4.0 2.0 0.0 User Limit jan apr jul oct jan apr jul oct jan apr jul oct jan Samples 11--® 02 03 04 05 Month / Year Graph 1 Detect ® Chloride for sample point MWO4 ND Man. outlier 500. 450. 400. 350. M 300. G 250. ■ ■ L 200. ■ ■ - ■— 150. 100. 50. 0. User Limit jan apr jul oct jan apr jul oct jan apr jul oct jan Samples I ■ 02 03 04 05 Month / Year Graph 2 Prepared by: Earth Tech 1 • • BRL [detwells] Analysis pi epared on 12/2/2004 FIGURE 4 Detect ■ Sodium-dissolved for sample point MWO3 ' ND Man. outlier 1000000. 900000. - 800000. 700000. U 600000. • G ■ • �- 500000. 400000. 300000. 200000. 100000. 0.User Limit Limit jan apr jul oct jan apr jul oct jan apr jul oct jan 02 03 04 05 Samples ■ Month / Year Graph 1 - - -- - - - -- - Detect ■ Sodium-dissolved for sample point e ND p MW06 Man. outlier 200000. 180000. 160000. 140000. e U 120000. ■ - I G 100000. 80000. 60000. 40000. 20000. 0. User Limit jan apr jul oct jan apr jul oct jan apr jul oct jan Samples® ■ 02 03 04 05 Month / Year Graph 2 Prepared by: Earth Tech 1 • FIGURE 5 Leachate, MW04 and MW06 Stiff Diagrams Cations meq/l Anions Na+K CI Ca ;2002 Leachate • ->•- HCO3+CO3 n^- Mg $04 Na+K I CI c2003 Leachate Hco3+Co3 Mg 504 Na+K CI (2004 Leachate HCo3+CO3 Mg SO4 Na+K CI MW04 2002(Pre-Disposal)_ Mg: I SO4 Na+K CI \Ca MW04 20041003+CO3 Mg .. .. .SO4 Na+K CI MW06 2002(Pre-Disposal) Mg SO4 Na+K ICI MW06 2004J3+co3 Mg SO4 Na+K CI I y\ (MW03032002(Pre-Disposal) Mg SO4 Na+K CI • Ca' MW03 200403+co3 Mg _.. SO4 ! • FIGURE 6 Leachate, MW04 and MW06 Piper Diagrams _ 2002 Leachate .c O .1 d� `i 2003 Leachate a¢' G c --- --_ 3,O -----\/-2004 Leachale c ??../N MWO4 2002(Pre-Disposal) o o 0 0 c. - - ' -- MWO4 2004 o_ o 0 0 0 O _ 9 ? Y O G O . f c i c i c a ,` -- El MW062002(Pre-Disposal) Total Dissolved Solids 3� MWO6 2004 (Parts Per Million) ti° %. -_ \ : aQ MWO3 2002(Pre-Disposal) t. —— — _— - - MWO3 2004 Mg SO4 o OO�� — G - 3�2 c.rty � to ° ^� _ A Ca ac CO 40 20 Na+K HCO .3 20 40 __ GO eo CI Calcium(Ca) Chloride(CI) CATIONS %meq/I ANIONS d DEPARTMENT OF PUBLIC HEALTH & ENVIRONMENT 1555 N. 17th Avenue pt Greeley, CO 80631 WEBSITE: www.co.weld.co.us ADMINISTRATION: (970) 304-6410 FAX: (970) 304-6412 O PUBLIC HEALTH EDUCATION & NURSING: (970) 304-6420 FAX: (970) 304-6416 ENVIRONMENTAL HEALTH SERVICES: (970) 304-6415 COLORADO FAX: (970) 304-6411 July 15, 2004 Mr. Alan Scheere Mr. Bill Hedberg Waste Management North Weld Sanitary Landfill 7780 E. 96th Avenue 40000 Weld County Road 25 Henderson, CO 80640 Ault, CO 80610-9748 Subject: North Weld Sanitary Landfill — 2nd Quarter Inspection, 2004 Dear Mr. Hedberg and Mr. Scheere: On June 23, 2004, I conducted a routine inspection of the North Weld Sanitary Landfill, located at 40,000 Weld County Road 25, in Weld County, Colorado. The purpose of the inspection was to inspect and assess the facility's compliance with the "Regulations Pertaining to Solid Waste Disposal Sites and Facilities" (the Regulations) as promulgated. by the Solid Waste Disposal Sites and Facilities Act, Title 30, Article 20, part 1, C.R.S., as amended, and the Development Standards set forth in the facility's Use By Special Review Permit number 895 (USR-895). On this date it was observed that the facility was in substantial compliance with both the Regulations and USR-895. If you have any questions regarding this inspection, please contact me at 970-304-6415, extension 2220. Sincerely, Cindi Etcheverry Environmental Health Supervisor Environmental Health Services Enclosure: Inspection cc: Trevor Jiricek, Director, Weld County Environmental Health Services (via email) Doug Ikenberry, Colorado Department of Public Health & Environment (w/encl) Kim Ogle, Department of Planning Services (via email) C:\Documents and Settings\kogle\Local Settings\Temporary Internet Files\0LK375\040623insp.doc 2- 7 .575 DTC Parkway, Su , nlewood, Colorado Soria-3oi6 October 31, 2003 Mr. Douglas Ikenberry, P.E. 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 Ms. Cindi Etcheverry Weld County Department of Public Health and Environment 1J 3D rsi. 17th Avenue Greeley, Colorado 80631 Re: North Weld Sanitary Landfill Telephone Second Semi-Annual 2003 Groundwater Sampling Report Project No. 65230.0601 3°3.694.6660 Facsimile Dear Mr. Ikenberry and Ms. Etcheverry: 3°3.694.441° Enclosed for your review is the Second Semi-Annual 2003 Groundwater Sampling Report for the North Weld Sanitary Landfill (NWSL). This report was prepared on behalf of Waste Management Disposal Services of Colorado, Inc. by Earth Tech, Inc. (Earth Tech). Sampling for the event occurred on September 17 and 18,2003,and Severn Trent Laboratories,Inc.performed laboratory analyses. Also enclosed is a 3.5-inch disk, which contains the analytical results for the second semi-annual 2003 sampling event as requested by the Colorado Department of Public Health and Environment. This was the fifthteenth detection-sampling event for these wells and there were no volatile organic compound detections during this event. Lead and zinc were detected at MW 12 for the fourth consecutive event. Statistical analyses were performed using intra-weii comparisons. antra-well Combined Shewart-CUSUM Control Charts were prepared for wells MW03, MW04, MW05, MW 10, and MW 12. The enclosed results of the statistical analysis are displayed in tabular and graphical format. The background period for the control charts currently includes data through March 2002,and CUSUM is currently calculated starting at the end of the background period. The statistical evaluation from the second 2003 semi-annual event showed an initial CUSUM control limit exceedance for sulfate in MW03. MW03 is an upgradient well, however, and not subject to verification sampling. The statistical evaluation from the second 2003 event also showed initial control limit exceedances for detections of lead and zinc. Lead and zinc were detected at 8.2 micrograms per liter (µg/L) and 50 µg/L, to control limits of 7.2 /L and 46.4 L. These detections will respectively, relative µg µ� EARTH TECH A two INTERNATIONAL LTD.COMPANY Mr. Douglas Ikenberry Ms. Cindi Etcheverry October 31, 2003 Page 2 be subject to verification sampling during the next monitoring event currently scheduled for March 2004. During the first semi-annual 2003 sampling event,MW04,MW05,and MW 12 did show an initial exceedance for the field measurement of pH. Due to the highly variable nature of field-specific measurements and because field pH is not truly considered part of the NWSL statistical evaluation, this is not a concern. The pH levels in these wells, however, fell within the control limit during the second semi-annual 2003 sampling event. Should you have any questions concerning this report,please call me at(303)694-6660. Very truly yours, Earth Tech, Inc. Randy Thompson. Environmental Engineer Enclosures cc Alan Scheere, WMI Bill Hedberg, NWSL Kim Ogle, WCDPS w/o encl. work\65230\product\nwsl\2nd03 semi.doc EARTH x TECH A Tyco Infrastructure Services Company t • DTC suite 200, Lnglevood, Colorado Sol I-3olh Weld County Planning Department GREELEY OFFICE JUL 2 3 2002 July 22, 2002 RECEWED Mr. Doug Ikenberry, P.E. Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, Colorado 80222-1530 Ms. Cindi Etcheverry Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Colorado 80631 Re: North Weld Sanitary Landfill First Semi-Annual 2002 Groundwater Sampling Report Project No. 54160.0701 30).6,4 6664, Dear Mr. Ikenberry and Ms. Etcheverry: Enclosed for your review is the First Semi-Annual 2002 Groundwater Sampling Report 344i 3.69,4.4-I for the North Weld Sanitary Landfill (NWSL). This report was prepared on behalf of Waste Management Disposal Services of Colorado, Inc. by Earth Tech, Inc. (Earth Tech). Sampling for the event occurred on March 20 and 26, 2002, and Severn Trent Laboratories, Inc. performed laboratory analyses. Also enclosed is a 3.5-inch disk, which contains the analytical results for the first semi-annual 2002 sampling event as requested by the Colorado Department of Public Health and Environment. At the request of the Weld County Department of Public Health and Environment, Earth Tech has omitted Chain of Custody and Field Information Forms from the submittal report; however, the complete report including these forms are maintained in the facility's operating record. This was the twelfth detection sampling event for these wells and there were no volatile organic compound detections during this event. Lead and zinc were detected at MW12. Statistical analyses were performed using intra-well comparisons. Intra-well Combined Shewart-CUSUM Control Charts were prepared for wells MW03, MW04, MW05, MW 10, and MW12. The enclosed results of the statistical analysis are displayed in tabular and graphical format. The background period for the control charts currently includes data through March 2000, and CUSUM is currently calculated starting at the end of the background period. During the second 2001 sampling event, the only control limit exceedance was CUSUM for the field measurement of specific conductance at MW04. Due to the highly variable nature of field measurements, the field measurement of specific conductance is not truly considered part of the NWSL statistical evaluation program. A EA R T H TECH A'two INTERNATIONAL LTD.COMPANY t Mr. Doug Ikenberry Ms. Cindi Etcheverry July 22, 2002 Page 2 similar level was reported during this event. There was also a CUSUM exceedance for field-specific conductance in upgradient well MW03 during this event. The statistical analysis for the first 2002 semi-annual sampling event shows a potential control limit exceedance for lead and nitrate in well MW12 and nitrate in MW03. MW12 and MW03 are upgradient wells and not subject to verification sampling. There are also potential exceedances for nitrate and sulfate in MW04. Verification sampling will be conducted for these constituents as part of the next monitoring event. The next sampling event for these wells is scheduled for September 2002. Should you have any questions concerning this report, please call me at (303) 694-6660. Very truly yours, Earth Tech Inc. /Randy Thompsdn-P:E. Environmental Engineer Enclosures cc Alan Scheere, WMI Bill Hedberg, NWSL Kim Ogle, WCDPS w/o encl. work\54160\product\nwsl\1 st02gw.doc !. { F. i h .. ECH A tgCO INTERNATIONAL LTD.COMPANY d DEPARTMENT OF PUBLIC HEALTH & ENVIRONMENT 1555 N. 17th Avenue Greeley, CO 8O631 WEBSITE: www.co.weld.co.us ADMINISTRATION: (970) 304-6410 FAX: (970) 304-6412 Will es PUBLIC HEALTH EDUCATION & NURSING: (970) 304-6420 FAX: (970) 304-6416 ENVIRONMENTAL HEALTH SERVICES: (970) 304-6415 COLORADO FAX: (970) 304-6411 July 19, 2002 Alan Scheere Bill Hedberg Waste Management North Weld Sanitary Landfill 2090 E. 104th Ave. #300 40,000 Weld County Road 25 Denver, CO 80233 Ault, CO 80610-9748 Subject: North Weld Sanitary Landfill—Updated Waste Identification Plan Dear Mr. Scheere and Mr. Hedberg: The Weld County Department of Public Health and Environment (the Department) has reviewed the Waste Identification Plan, updated April 2002 and received in our office April 30,2002. Based on our review of the information provided, and Doug Ikenberrys' July 10, 2002 modifications, the Depai tuient concurs that the Waste Identification Plan is in accordance with the facility's Special Review Permit (USR-895)and the requirements of the CDPHE. If you have any questions,please do not hesitate to call me at(970)304-6415, extension 2220. Sincerely, ' Cindi Etcheverry Environmental Specialist Environmental Health Services cc: Trevor Jiricek,Director, Weld County Environmental Health Services (via email) Doug Ikenberry, Colorado Department of Public Health and Environment Lee Morrison, Weld County Attorneys Office(via email) Kim Ogle, Weld County Department of Planning Services(via email) O:\ETCH\WASTE\Nwsl\020719wip approval.doc 4- 4 STATE OF COLORADO Bill Owens,Governor Jane E.Norton,Executive Director 4 of cot()P Dedicated to protecting and improving the health and environment of the people of Colorado o 4300 Cherry Creek Dr.S. Laboratory and Radiation Services Division Denver,Colorado 80246-1530 8100 Lowry Blvd. *1876* Phone(303)692-2000 Denver,Colorado 80230-6928 TDD Line(303)691-7700 (303)692-3090 Colorado Department Located in Glendale,Colorado Weld County Planning Department of Public Health http://www.cdphe.state.co.us CR E[_EY OFFICE and Environment JUL 1 9 2002 July 10, 2002 RECEVED Mr. Alan Scheere Waste Management 7780 E. 96th Ave. Henderson, CO 80640 RE: North Weld Sanitary Landfill Waste Identification Plan (Updated April 2002) Dear Mr. Scheere, The Hazardous Materials and Waste Management Division of the Colorado Department of Public Health and Environment (Division) has completed our review of the North Weld Sanitary Landfill Waste Identification Plan (updated April 2002). Barring any objections, a copy of this letter shall serve as an errata supplement (to be inserted in the plan) regarding the modifications listed below: 1) Replace "Updated May 2002" shown at the bottom right hand corner of the pages in the plan with "Updated April 2002." 2) Page 1, 2nd par., 1st sentence—Replace "2.2.1 (B)"with "2.1.2 (B)." 3) Page 1, 3rd par., 1st sentence—Replace "1107-2"with"1007-2." 4) Page 2, 2nd par., only sentence—Replace"25-15-101(g)"with"25-15-101(6)(a)." 5) Page 2, 2nd par., only sentence—Replace "Colorado Hazardous Waste Act"with"Colorado Revised Statutes." 6) Page 4, 3rd par., 1st sentence—Replace "that that "with "and that." 7) Attachment 1, Generator's Waste Profile Instruction Sheet, 1St bullet under item B.2— Replace "stores"with"stored." 8) Attachment 1, Generator's Waste Profile Instruction Sheet, item B.6—Delete "the"between "describes" and "when." r I Mr. Alan Scheere July 10, 2002 Page 2 if have an I may be contacted at 303-692-3389 y ou y questions and/or concerns.q Sincerely, bnAciL6`74/c. J/62-ivv-1 Douglas M. Ikenberry Solid Waste Unit Compliance Program Cc: Cindi Etcheverry, Weld County Department of Public Health and Environment Julie Chester, Weld County Department of Planning Services FILE: SW WLD NWC 2.2 41. STATE OF COLORADO Bill Owens,Governor Jane E.Norton, Executive Director COtOP Dedicated to protecting and improving the health and environment of the people of Colorado o 4300 Cherry Creek Dr.S. Laboratory and Radiation Services Division Denver,Colorado 80246-1530 8100 Lowry Blvd. 1876 Phone(303)692-2000 Denver,Colorado 80230-6928 TDD Line(303)691-7700 (303)692-3090 Colorado Department Located in Glendale,Colorado of Public Health http://www.cdphe.state.co.us and Environment July 10, 2002 Mr. Alan Scheere Waste Management 7780 E. 96th Ave. Henderson, CO 80640 RE: Buffalo Ridge Landfill Waste Identification Plan (Updated April 2002) Dear Mr. Scheere, The Hazardous Materials and Waste Management Division of the Colorado Department of Public Health and Environment (Division) has completed our review of the Buffalo Ridge Landfill Waste Identification Plan (updated April 2002). Barring any objections, a copy of this letter shall serve as an errata supplement (to be inserted in the plan) regarding the modifications listed below: 1) Cover Sheet—Replace "Waste Management of Colorado, Inc."with"Waste Management Disposal Services of Colorado, Inc." 2) Page ii—Replace "Stormwater Management Plan"with "Waste Identification Plan." 3) Page 1, 3rd par., 15t sentence—Replace "1107-2"with"1007-2." 4) Page 1, 4th par., 1st sentence—Replace "appendix A, subpart F"with"appendix E, subpart E." 5) Page 2, 3rd par., only sentence—Replace "25-15-101(g)"with "25-15-101(6)(a)." 6) Page 2, 3rd par., only sentence—Replace "Colorado Hazardous Waste Act" with"Colorado Revised Statutes." 7) Page 2, 6th par., only sentence—Replace "Waste Management of Colorado, Inc. (WMC)" with"Waste Management Disposal Services of Colorado, Inc. (WMDSC)." 8) Page 2, 8th par., only sentence - Replace "WMC - Waste Management of Colorado, Inc." with"WMDSC - Waste Management Disposal Services of Colorado, Inc." I Mr. Alan Scheere July 10, 2002 Page 2 9) Page 3, 2nd bullet, 1st sentence—Replace "WMC"with "WMDSC." 10) Page 3, last par., 3rd and 4th sentences—Replace "WMC"with"WMDSC." 11) Page 4, 2nd par., only sentence—Replace "WMC/BRL"with "WMDSC/BRL." 12) Attachment 1, Generator's Waste Profile Instruction Sheet, 1st bullet under item B.2— Replace "stores"with"stored." 13) Attachment 1, Generator's Waste Profile Instruction Sheet, item B.6—Delete "the"between "describes" and "when." I may be contacted at 303-692-3389 if you have any questions and/or concerns. Sincerely, (5.‘A credo Llik•° L2j12AA'<e' Douglas M. Ikenberry Solid Waste Unit Compliance Program Cc: Cindi Etcheverry, Weld County Department of Public Health and Environment Kim Ogle, Weld County Department of Planning Services FILE: SW WLD BRL 2.2 NORTH WELD SANITARY LANDFILL W A WASTE MANAGEMENT COMPANY 40,000 Weld County Road 25 Ault,Colorado 80610-9748 (970)686-2800 (970)686-1031 Fax April 26, 2002 Mr. Douglas Ikenberry, P.E. Colorado Department of Public Health and Environment Hazardous Materials Waste Management Division HMWMD-SWIM-B2 4300 Cherry Creek Drive South Denver, CO 80246-1530 Ms. Cindi Etcheverry Weld County Department of Public Health and Environment 1555 17th Avenue Court Greeley, CO 80631 Subject: Buffalo Ridge Landfill and North Weld Sanitary Landfill Updated Waste Identification Plans Dear Mr. Ikenberry and Ms. Etcheverry: As indicated in our letter of March 8, 2002 regarding the opening of the Buffalo Ridge Landfill (BRL), we are currently reviewing existing plans and permits to ensure compliance and to identify any changes or updates that may be necessary. We have completed our review of the existing BRL Waste Identification Plan (WIP) dated April 1998, which was previously approved by the Colorado Department of Public Health and Environment (CDPHE) and Weld County Department of Public Health and Environment (WCDPHE) on May 12, 1998 and May 18, 1998 respectively. Our review indicates only minor changes are necessary to the WIP and include the following: • The addition of an Errata Sheet to track future changes; • Replacement of the Generator Waste Profile Sheet (GWPS) included in Attachment 1 with a revised GWPS which is currently used by all Waste Management landfills in Colorado as part of their waste acceptance programs. Accordingly, enclosed for your information is a copy of the updated plan titled "Waste Identification Plan" (WIP) dated April 2002, prepared by Waste Management of Colorado, Inc. for the BRL. Since our North Weld Sanitary Landfill (NWSL) and BRL plans have been prepared following the same waste screening procedures and protocols we have also made those changes as Weld County Planning Department GREELEY OFFICE Letter Douglas Ikenberry and Cindi Etcheverry APR 3 0 2002 April 26,2002 Page 2 RECEIVED described above to the NWSL WIP in order to maintain consistency in the plans for both facilities. Therefore, we have also enclosed an updated Waste Identification Plan dated April 2002, for NWSL. This WIP updates the previously submitted and approved plan dated April 1998. The focus and procedures of the updated BRL and NWSL WIPs have not changed and continue to serve as a PCB and hazardous waste screening mechanism in accordance with Section 2.1.2 of the Regulations Pertaining to Solid Waste Disposal Sites and Facilities (Regulations) (6 CCR 1007-2) revised September 2000. If you have any questions regarding the updated WIPs for BRL and NWSL, please contact either Alan Scheere at 303.280.9336 or Jack Epple (BRL Site Manager) at 303.732.0218 or Bill Hedberg (District Manager, BRL and NWSL) at 970.686.2800. Sincerely, Alan Scheere Environmental Specialist Enclosure cc: Julie Chester, WCDPS w/o enc. NORTH WELD SANITARY LANDFILL A WASTE MANAGEMENT COMPANY a 40,000 Weld County Road 25 Ault,Colorado 80610-9748 (970)686- April 23, 2002 (970)686-1031 030 Fax Mr. Doug Ikenberry, P.E. Colorado Department of Public Health and Environment Weld County Planning Department GREELEY OFFICE Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 APR 2 5 2002 4300 Cherry Creek Drive South Denver, CO 80222-1530 RECEIVED Ms. Cindi Etcheverry Weld County Department of Public Health.and Environment 1535 17th Avenue Greeley, CO 80631 SUBJECT: NORTH WELD SANITARY LANDFILL (NWSL) FIRST QUARTER 2002 GAS MONITORING REPORT Dear Mr. Ikenberry and Ms. Etcheverry: Enclosed for your information is the First Quarter 2002, Gas Monitoring Report for North Weld Sanitary Landfill (NWSL). The gas monitoring and corresponding report was completed by Waste Management Disposal Services of Colorado, Inc. The gas report contains monitoring results from the Phase 1 perimeter soil gas probes (GP) GP-14 through GP-20, structure probes GP-1 and GP-2 and inside the shop and office. The gas monitoring report indicates that combustible gas was not detected in any perimeter probes or on-site structures. If you have any questions regarding this report, please call me at (303) 280-9336 or Bill Hedberg at (970) 686-2800. Sincerely, Alan Scheere Environmental Specialist cc: Julie Chester, WCDPS, w/o enc. word\letter\nwgsrl F: nwsl 4.2.5.01 NORTH WELD SANITARY LANDFILL GAS MONITORING REPORT WELD COUNTY,CO. Page 1 of 4 Date: 25-Mar-02 Analyst: Alan Scheere Water Level Indicator: Solinst 150ft. SN 22483 Pressure Gauge: Neotronics PDM205 SN 1173421 Gas Detector: MSA Gasport S/N BO-3632 Date Calibrated: 25-Mar-02 Sampling Device: Electrical/internal Pump Time: 12:30 Temp (F): 35 Soil Condition: Dry Bar. Pressure: NR Wind: calm (1) (2) (3) DEPTH DEPTH PROBE OF TO % PRESSURE LOCATION PROBE WATER CH4 IN. W.C. GP-2 14.1 Dry 0.0 0.02 GP-15 51.2 Dry 0.0 0.00 ................................................................................................................ GP-17 32.2 Dry 0.0 0.03 GP-19 37.4 Dry 0.0 0.00 (1)-GP-1,GP-2.4 GP-14 THRU GP-20 MONITORED QUARTERLY. (2)-WATER LEVELS OBTAINED QUARTERLY. (3)-METHANE READINGS ARE 0 TO 100 PERCENT BY VOLUME IN AIR. COMMENTS: (WEATHER CONDITIONS, OBSERVATIONS, ETC.): Sunny, cool Wind: calm Total depth values were obtained during the March 2002 monitoring with the Solinst Tape N/A-(NOT APPLICABLE) C'WalaLxceMONITORIIGASWWSLVGaatlWaa12002tbIPAGE 1 NORTH WELD SANITARY LANDFILL GAS MONITORING REPORT SUPPLEMENTAL BARHOLE PROBING Page 2 of 4 ANALYST: Alan Scheere INSTRUCTIONS: 1. At the present probe locations in which a gas concentration greater than 1% is detected, monitor the corresponding "A" series barhole location. 2. In a similar manner, monitor B, C, etc. series barhole locations, progressing outward from the probe until no further gas is detected and the extent of migration is determined. BAR HOLE PROBE LOCATIONS PERMANENT PROBE @ 10' @ 20' @ 30' @ 40' @ 50' LOCATION % GAS A B C D E NO BARHOLE PROBES WERE PERFORMED DURING THIS EVENT *NOTE: ALL READINGS ARE 0 TO 100 PERCENT METHANE BY VOLUME IN AIR NORTH WELD SANITARY LANDFILL WELD COUNTY,CO. STRUCTURE SAMPLING SHOP Page 3 of 4 ANALYST: Alan Scheere PHONE: 280-9336 DATE: 3/25/02 INSTRUMENT TYPE: MSA Gasport SERIAL#: 3632 DATE INSTRUMENT CALIBRATED: 3/25/02 1 3 5 2 4 6 7 8 9 10 SAMPLE POINT DESCRIPTION % METHANE 2 SHOP(CEMENT FLOOR) 0 :.......... Q I� 4 SHOP (CEMENT FLOOR) 0 6 STORAGE(CEMENT FLOOR) 0 . ... . ............................ 8 SHOP (CEMENT FLOOR) 0 10 SHOP(CEMENT FLOOR) 0 ALL READINGS 0 TO 100%METHANE BY VOLUME IN AIR In addition to the above listed sample points, all plumbing, electrical, HVAC, foundation cold joints and cracks are monitored. If any concentration of gas is detected, these points are identified on the sketch. NORTH WELD SANITARY LANDFILL Weld County, CO Structure Sampling Office Page 4 of 4 ANALYST: Alan Scheere PHONE: 280-9336 DATE: 3/25/02 INSTRUMENT TYPE: MSA Gasport SERIAL#: 3632 DATE INSTRUMENT CALIBRATED: 3/25/02 1 3 2 4 9 8 5 7 6 SAMPLE POINT DESCRIPTION % METHANE 2 ::::::...........................:.::::RECEPTION AREA 0 4;.::.::.::........................::::::::.LUNCH ROOM;<;,:.::................................. ....................... .......................... ....................... 0 6 STORAGE 0 .................................:......... ...::.::.::::.:::::.................... 8 REST ROOM 0 ALL READINGS 0 TO 100% METHANE BY VOLUME IN AIR In addition to the above listed sample points, all plumbing, electrical, HVAC, foundation cold joints and cracks are monitored. If any concentration of gas is detected, these points are identified on the sketch. NORTH WELD SANITARY LANDFILL £r.. �,x A WASTE MANAGEMENT COMPANY s� 40,000 Weld County Road 25 Ault,Colorado 80610-9748 (970)686-2800 April 18, 2002 (970)686-1031 Fax Weld County Planning Department Mr. Douglas Ikenberry, P.E. GREELEY OFFICE Colorado Department of Public Health and Environment Hazardous Materials and Waste Management Division APR 2 2 2002 HMWMD-SWIM-B2 RECEIVED 4300 Cherry Creek Drive South Denver, CO 80222-1530 Ms. Cindi Etcheverry Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Co 80631 Subject: North Weld Sanitary Landfill (NWSL) Phase 2 Module 1 Leachate Collection System Dear Ms. Etcheverry and Mr. Ikenberry: This letter is in response to the Colorado Department of Public Health and Environment (CDPHE) letter dated March 20, 2002 regarding the leachate collection system (LCS) design modification commencing with the construction of Phase 2 Module 1 at North Weld Sanitary Landfill (NWSL). The CDPHE letter indicates that the CDPHE and Weld County Department of Public Health and Environment (WCDPHE) had no objections to the proposed conceptual LCS design. However you further state that, "it is inappropriate to fully approve this design modification until we see it incorporated into the context of the entire Phase 2 Module 1 design submittal." Accordingly, we are providing the following documents for your information and request your approval for the LCS design modification for the NWSL. These documents reflect the LCS design modification as discussed during our February 5, 2002 meeting at which time the CDPHE and WCDPHE approved the conceptual LCS design modification. • North Weld Sanitary Landfill Phase 2 Module 1 Liner System Construction Quality Assurance Plan April 2002 c: d ata\letter\N W SL\Apri 12002 File: 4.1.6 p Letter Cindi Etcheverry and Douglas Ikenberry April 18,2002 Page 2 • Technical Specification for Phase 2 - Module 1 Cohesive Soil Liner and Leachate Collection System North Weld Sanitary Landfill Weld County, Colorado April 2002. • Construction Drawings for Waste Management Disposal Services of Colorado, Inc. North Weld Sanitary Landfill, Phase 2 Module 1 Weld County, Colorado March 20, 2002, Sheets 1-5 (Separately bound) Also enclosed as requested by CDPHE in its letter dated March 20, 2002, is a report prepared by Golder Asssociates dated April 17, 2002 that includes site specific calculations to document compliance with the requirements of Subsection 3.2.5(D)(1) of the Regulations Pertaining to Solid Waste Disposal Sites and Facilties, CCR 1007-2 (Regulations). This report documents compliance with the Regulations in Phase 2 and Phases 3a and 3B at NWSL. The leachate collection system design in Phase 3b will be modified as shown on the attached drawing in order to comply with the requirements of the Regulations prior to module construction in this phase. Should you have any questions concerning this request or the Phase 2 Module 1 construction project please contact me at 303. 280.9336 or Bill Hedberg at 970.686.2800. Sincerely, di/gLit c 4"-e Alan Scheere Project Manager cc: Julie Chester, WCDPS, w/o enc. }o NORTH WELD SANITARY LANDFILL „ A WASTE MANAGEMENT COMPANY 71 40,000 Weld County Road 25 Ault,Colorado 80610.9748 (970)686-2800 March 28, 2002 (970)686-1031 Fax Mr. Long Nguyen Colorado Department of Public Health and Environment Air Pollution Control Division APCD-SS-B1 4300 Cherry Creek Drive South Denver, CO 80246-1530 SUBJECT: NORTH WELD SANITARY LANDFILL (NWSL) TITLE V OPERATING PERMIT SEMI-ANNUAL MONITORING REPORTS Dear Mr. Nguyen: In accordance with the NWSL Title V Operating Permit # 97OPWE181, enclosed are the following semi-annual Monitoring and Permit Deviation Reports. • Monitoring and Permit Deviation Report - Part I • Monitoring and Permit Deviation Report - Part III - Report Certification Part II of the Monitoring and Permit Deviation Reports was not completed because there were no permit deviations, upset or emergency conditions that occurred during this reporting period. These reports cover the monitoring period of September 1, 2001 - February 28, 2002. The submittal deadline for these reports is April 1, 2002 Should you have any questions regarding these reports, please contact Alan Scheere at (303) 280-9336 or Bill Hedberg at (970) 686-2800. Sincerely, --� diet/4 ..ccileeit)._ Alan Scheere Bill Hedberg Environmental Specialist District manager Enclosures Cc: Doug Ikenberry, CDPHE, w/enc. Cindi Etcheverry, WCDPHE, w/enc. Julie Chester, WCDPS, w/o enc. • NORTH WELD SANITARY LANDFILL - _ A WASTE MANAGEMENT COMPANY t _ 40,000 Weld County Road 25 Ault,Colorado 80610-9748 (970)686-2800 May 30, 2001 (970)686-1031 Fax Weld County Planning Dept. Mr. Douglas lkenberry, P.E. Colorado Department of Public Health and Environment 7 Z., Hazardous Materials and Waste Management Division HMWMD-SWIM-B2 RECEIVED 4300 Cherry Creek Drive South V Denver, Co 80222-1530 Ms. Cindi Etcheverry Weld County Department of Public Health and Environment 1555 N. 17th Avenue Greeley, Co 80631 Subject: North Weld Sanitary Landfill (NWSL) Updated Groundwater Monitoring Plan USR#895 Dear Mr. Ikenberry and Ms. Etcheverry: Enclosed is an updated Groundwater Monitoring Plan (text and corresponding attachments) for the NWSL. This plan was updated pursuant to Development Standard #8 of the Weld County Certificate of Designation. This Development Standard requires the plan to be reviewed at least once every two years. The NWSL plan was previously reviewed, updated and submitted to the Colorado Department of Public Health and Environment (CDPHE) and Weld County Department of Public Health and Environment (WCDPHE) in May 1999. The NWSL Groundwater Monitoring Plan was reviewed and modified by NWSL and includes general plan updates/revisions since the previous plan submittal. These plan revisions are described below: • Updated Revision Summary page. • The contractor providing analytical services to NWSL has changed its name from Quanterra Incorporated (Quanterra) to Severn Trent Laboratories (STL) of Denver. Accordingly references to Quanterra have been changed to STL of Denver throughout the plan. • Revised the.List of Appendices and added the Laboratory Quality Manual for STL Denver to the appendices list. c:\data\letter\nwsl\upgrwp1n2001 File:4.1.6 , Letter Douglas Ikenberry and Cindi Etchevery May 30,2001 Page 2 • Updated information included in Appendix 8 (Replaced Quanterra Quality Assurance Management Plan with Laboratory Quality Manual for STL Denver). • Revised Section 9.0 (Page 26) and added Laboratory Quality Manual for STL Denver to the reference list. • Updated information included in Appendix 4 (Directory). • Changed the title page of Appendix 8 from Quanterra Quality Assurance Management Plan to Laboratory Quality Manual for STL Denver. • Updated the description of the leachate collection system at the top of page 1.6 to reflect the approved design modification. This sentence now reads "The leachate collection system at NWSL consists of three components; 1) Leachate Collection Trenches; 2) A 6" Drainage Blanket overlying the 2-foot compacted clay liner; and 3) Leachate Collection Sumps. Please replace the existing information, which have been revised as described above, with the enclosed text and corresponding pages. If you have any questions concerning these revisions, please contact either of us at (303) 280- 9336 (Alan Scheere) or (970) 686-2800 (Bill Hedberg). Sincerely, 61k- Alan Scheere Bill Hedberg Environmental Specialist - District Manager Enclosure AS/as cc: Julie Chester, WCDPS, w/o enc. Randy Thompson, Earth Tech, w/enc. Hello