Document 85Qq2voKZn4ejqN2drm6JvZye

SUBJECT: FROM: THRU: TO: CLEAN AIR ACT INSPECTION REPORT Tower Landfill, Commerce City, CO Enforcement and Compliance Assurance Division, Air and Toxics Enforcement Branch Branch Manager Enforcement and Compliance Assurance Division, Air and Toxics Enforcement Branch File BASIC INFORMATION Facility Name: Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 EPA Inspector(s): 1. 2. Tower Landfill Attendees: 1. General Manager 2. , Environmental Manager 3. , Site Operations Manager Contact Email Address: Purpose of Inspection: To determine Clean Air Act (CAA) compliance, including comparative Method 21 surface emission monitoring (SEM). Facility Type: Municipal solid waste (MSW) landfill Regulations Central to Inspection: Colorado's 111(d) State Plan for MSW landfills implementing 40 C.F.R. Part 60, Subpart Cf (State Plan); 40 C.F.R. Part 63, Subpart AAAA - National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Municipal Solid Waste Landfills (NESHAP AAAA); Title V Permit Requirements of Operating Permit 99OPAD220 (Permit #99OPAD220) Date: Arrival Time: Departure Time: 10/17/2023 9:00 MDT 16:20 MDT Inspection Type: Unannounced Inspection Announced Inspection OPENING CONFERENCE Presented Credentials Stated authority and purpose of inspection Provided Small Business Resource Information Sheet Small Business Resource Information Sheet not provided. Reason: Not a small business Provided CBI warning to facility The following information was obtained verbally from Tower Landfill representatives or through review of facility records. Process Description: The Tower Landfill (TLF) is a municipal solid waste (MSW) landfill located in Commerce City, Colorado and is owned by Allied Waste Systems of Colorado, LLC (Allied). Allied is a wholly owned subsidiary of Republic Services, Inc. The facility is subject to the requirements of the State Plan, NESHAP AAAA, and Permit #99OPAD220. TLF began operations in 1981 and accepts municipal solid waste, construction and demolition debris, non-hazardous industrial wastes, liquid waste, contaminated soils, and both friable and non-friable asbestos. The landfill's current maximum design capacity is 44,405,343 Megagrams (Mg) by mass and 50,917,918 cubic meters by volume, with an expected closure date in 2044. TLF receives approximately 6,000 tons of waste per day, a majority of which is MSW. Permit #99OPAD220 limits the waste acceptance rate to 2,880,288 tons per year. In recent years, the landfill has accepted approximately 900,000 short tons per year of waste and currently has approximately 20,000,000 Mg of Waste-In-Place. Other wastes, such as construction and demolition waste as well as asbestos waste, are comingled for disposal with MSW. Since there Page 2 of 10 are no dedicated monofils at the landfill, all portions of the landfill with waste-in-place for greater than five years are under active landfill gas (LFG) collection. The northwestern half of the landfill is under final cover. The remainder of the landfill is under intermediate cover. During the inspection, the active landfill face was located centrally within the eastern half of the landfill. See Appendix D, containing a map of the landfill, for the approximate location of the working face. Condensate and leachate collected at TLF was not being recirculated at the time of the inspection. In December 1999, TLF reported non-methane organic compound (NMOC) emissions of 137.8 Mg/yr based on an April 1997 Tier II gas sampling test, which exceeded the 50 Mg/yr threshold for installing a gas collection and control system (GCCS). A GCCS design plan was submitted in November 1999 and the initial GCCS was subsequently installed and began operation in 2001. At the time of the inspection, the GCCS consisted of approximately 100 vertical landfill gas extraction wells. The LFG collection system spans all areas where waste has been in place for at least 5 years. The TLF GCCS control system is currently equipped with one enclosed flare rated to accommodate an inlet LFG flow of up to 4,000 standard cubic feet per minute (scfm). This flare was brought online on February 9, 2023, to replace a 1,600 scfm flare that was installed in 2003 and decommissioned February 6, 2023. According to a GCCS design plan prepared by TLF in 2023 (2023 Design Plan), EPA Landfill LandGEM modeling predicts LFG generation of 4,067 scfm in 2024, 4,214 scfm in 2025, and 4,365 scfm in 2026, with declining LFG generation thereafter. TLF assumes 75% of LFG is captured through the GCCS, with the remaining 25% uncollected and venting directly through the landfill surface. Surface Emission Monitoring: According to the 2023 TLF GCCS Design Plan, the GCCS is design to extract LFG at a sufficient rate to minimize subsurface lateral migration and surface emissions of LFG. Among other monitoring and operational practices, TLF is required to conduct quarterly surface emission monitoring (SEM) to verify the GCCS' ability to minimize LFG migration. Methane concentrations above 500 ppm discovered during a SEM event are considered exceedances and require that TLF perform corrective actions and follow-up monitoring to ensure the exceedance has been resolved. Exceedances are addressed by evaluating both the GCCS and intermediate/final cover systems. Historic SEM methane exceedances above 500 ppm are included in Table 1 below. Page 3 of 10 Alternatives Requested in the 2023 Design Plan: Through its 2023 Design Plan, TLF has proposed several alternatives for operating and monitoring practices which deviate from regulation or standard practice. Alternatives for wellhead monitoring exclusions and LFG extraction well decommissioning procedures are described briefly below. Well Monitoring In accordance with 60.38f(d)(2) and 63.1981(d) (2), TLF proposed excluding wells which are in "dangerous areas" of the site, such as raised wells and wells in active and/or construction areas, from monthly wellhead monitoring. Any times that a collection device is not monitored due to unsafe conditions, will be noted in the State Plan/NESHAP AAAA reports. Additionally, TLF has specified that the site intends to exclude any collection devices installed prior to the deadlines required by the State Plan/NESHAP AAAA from the operational, monitoring, and/or recordkeeping requirements of the State Plan/NESHAP AAAA until the age of the initial waste placed in the affected area reaches five years old if active, or two years if closed or at final grade. This alternative is supported by a May 31, 2007 approval from EPA Region 4. Well Decommissioning The 2023 Design Plan describes a decommissioned well as a well that is shut down for a period of time by fully closing the well valve. Examples of when it might be necessary to decommission a well may include if the well temperature becomes elevated and must be turned off as a remedial method for a period of time, or if a well is shut down based on poor gas quality until the gas is able to recharge sufficiently. A decommissioned well is maintained for potential future use, differentiating it from an abandoned well which is not maintained for future use. The following procedure will be used for decommissioned wells. The reason that the well was decommissioned will be noted in the monthly monitoring records; The decommissioned well will still be monitored monthly per State Plan and NESHAP requirements; Although, the pressure may be positive for a decommissioned well, the temperature levels must continue to meet and be monitored per State Plan and NESHAP requirements; The well may be temporarily opened during a monitoring event or left open only very slightly to relieve pressure buildup; Quarterly surface monitoring will continue as if the well was active to document fugitive gas emissions are still in control. If a well remains decommissioned for six consecutive months, the site will determine if the well should be abandoned. If it is determined to keep the well decommissioned, the site will continue to evaluate the well as described. TLF also proposed that extraction wells may be re-drilled, abandoned, and/or decommissioned without prior approval from CDPHE or EPA, provided that a written statement indicating that the landfill will still have sufficient well density in compliance with the State Plan/NESHAP AAAA and a certified updated GCCS layout drawing by a professional engineer Page 5 of 10 are provided in the semi-annual State Plan/NESHAP AAAA report. These procedures were approved as alternative operating scenarios as detailed in EPA clarification letters dated February 9, 2005 and February 12, 2003. Please note that EPA no longer concurs with well decommissioning procedures as an appropriate alternative operating scenario. In 2023 EPA design plan review communications, EPA asserts that a "decommissioned well" under Clean Air Act (CAA) landfill regulations is clearly a well that is permanently abandoned. EPA's position is that a landfill must obtain approval before either decommissioning or abandoning a well consistent with procedures set forth in CAA landfill regulations. TOUR INFORMATION EPA Tour of the Facility: Yes Data Collected and Observations: EPA conducted a partial SEM and cover integrity survey of the facility. EPA used two ThermoFisher Toxic Vapor Analyzer 2020s (TVA2020) to perform EPA Reference Method 21 for the SEM survey. EPA confirmed each reading with both TVA2020s and also offered TLF representatives the opportunity to visually confirm each exceedance above 500 ppm measured on the TVA2020 during the SEM survey. and of TLF visually confirmed all exceedances. See Appendix C for additional instrument and calibration information. The EPA SEM survey covered portions of the north-east and south-central slopes of the landfill, estimated to constitute roughly 10% of the area routinely monitored during quarterly SEM events. EPA did not monitor any portions of the western half of the landfill, which has been under final cover for several years. Additionally, EPA inspectors were limited to SEM monitoring only along the slopes of the eastern half of the landfill in order to avoid the working face, which extended throughout the top-central portions of the eastern cell and was designated as unsafe to monitor by TLF staff. Areas monitored during the EPA SEM survey were selected in accordance with regulatory requirements, focusing on locations with visual indicators of elevated landfill gas (e.g., distressed vegetation, cracks, seeps, cover penetrations) and areas with sparse vegetation, which are also prone to elevated emissions. EPA inspectors recorded 26 points on the landfill surface where methane concentrations equaled or exceeded 500 ppm, including 11 exceedances recorded at penetrations and 15 exceedances recorded on the landfill surface. Note that exceedance #26 of Appendix B is labeled as a penetration exceedance, although it does not meet TLF's definition of a penetration. See Appendix B for more details. In nearly all areas with recorded SEM exceedances, EPA inspectors observed concurrent cover integrity issues, such as large continuous areas with little to no vegetation, exposed waste, loose soil, and erosion rills. This information is captured in Appendix B; however, a description of three areas where significant cover integrity issues coincided with SEM exceedances is also Page 6 of 10 included below to provide additional details: 1. On the northern slope, EPA inspectors observed large swaths of unburied waste and loose dirt. The area was part of the working face several months prior, although the working face had shifted south, and large amounts of waste remained exposed at the time of the inspection. This area is associated with exceedances #4 - #6 and is captured in images IMG_0001.JPG - IMG_0005.JPG of Appendix A and satellite images 4, 5, and 6 of Appendix D. 2. On the central portion of the eastern slope, EPA inspectors discovered a large, continuous swath of unburied waste with vegetation, including an unknown variety of fruiting melon, growing through the waste. Some of the melons were fully developed (IMG_0018 and IMG_0019), indicating that this patch of waste had been left unburied for at least 80-100 days (average period for melons to mature from seed), which corresponds to at least 3 monthly cover integrity monitoring events. TLF representatives initially guessed the unburied waste had only been left unburied for a week. However, upon sighting the melons in the waste, they concurred with EPA that the waste had been left unburied for at least several months. This area is associated with exceedance #17 and is captured in images IMG_0016.JPG - IMG_0021.JPG and satellite images 4 and 7 of Appendix D. 3. On the northern portion of the eastern slope, EPA inspectors noted sparse vegetation, exposed waste, loosely packed dirt, and extensive erosion. Although the satellite image resolution is poor, satellite image 9 of Appendix D demonstrates that there has been a "T"-shaped area with sparse vegetation and erosion since at least July 14, 2022. It is widely recognized that establishing landfill surface vegetation helps mitigate erosion, minimizing potential pathways for landfill gas to escape. Consistent with areas with persistent lack of vegetation, the "T"-shaped subject area displayed signs of erosion observed by EPA inspectors. Given the observed erosion and lack of vegetation, SEM was appropriately conducted in the area, revealing methane exceedances (#13-15). Furthermore, SEM exceedances were detected in the same area during TLF SEM events during the first and third quarters of 2023. This data, along with EPA inspector observations, support this area as a persistent source of surface emissions requiring attention. This area is associated with exceedances #13 - #15 and is captured in images IMG_0013.JPG - IMG_0014.JPG and DSCN0002.JPG of Appendix A and satellite images 4 and 9 of Appendix D. 4. On the south-eastern slope, EPA inspectors noted large erosion rills running the extent of the slope from top to bottom with very little vegetation established on the slope. This area is associated with exceedances #22 - #24 and is captured in images IMG_0026.JPG - IMG_0033.JPG of Appendix A and satellite images 1, 3, and 8 of Appendix D. TLF representatives communicated that unprecedented rain events throughout the summer of 2023 had caused difficulties in cover maintenance, including the formation of erosion rills and Page 7 of 10 difficulty keeping waste buried. CLOSING CONFERENCE Provided U.S. EPA point of contact to the facility Compliance Assistance: None. Photos and/or Videos: were taken during the inspection. See Appendix A Field Measurements: were taken during this inspection. See Appendix B. Records: were not taken during this inspection. Publicly available records were reviewed as part of the inspection. Areas of Concern: The findings of the EPA SEM survey revealed facility SEM practices and cover integrity monitoring as potential areas of concern. Both concerns were discussed with TLF representatives during the EPA SEM survey as well as during the closing conference. The cover integrity issues detailed in the "Data Collected and Observations" section of this report were communicated with TLF representatives by EPA inspectors. According to discussions during the closing conference, TLF staff expressed concern that it was unlikely that monthly cover integrity monitoring was performed adequately in the months prior to the EPA inspection because the issues EPA inspectors noted "should have been obvious in August and September as well and should have been noted." TLF representatives indicated that they intended to meet with relevant staff to discuss deficiencies suspected in the cover integrity monitoring. TLF representatives also expressed that unprecedented rainfall in the months preceding the EPA inspection had created difficulties in many areas of the landfill's operations, including cover maintenance. During EPA's SEM survey, inspectors noted 26 exceedances. TLF conducted its Q3 2023 SEM survey in August 2023 and noted 22 exceedances. Although the number of SEM methane readings above 500 ppm found during the EPA SEM survey are similar to the Q3 2023 TLF SEM survey total number of exceedances, overall trends and discrepancies warrant concern. First, while the quantity of exceedances are similar, it is important to note that EPA's SEM survey covered only 10% of the total landfill surface. Additionally, aside from 2023 SEM surveys and two other quarterly SEM events, TLF had historically not recorded any methane exceedances during quarterly SEM. The exceptions since 2017 were in Q4 2022 when two exceedances were recorded, and Q3 2019 when five exceedances were recorded (See Table 1). Using satellite imagery and past exceedance data, a comparison of TLF's historical SEM findings within only the EPA monitored areas, as compared to EPA's 26 findings, can be completed. This comparison indicates that TLF's historical findings within the monitored area are significantly less than EPA's, with a maximum of 10 exceedances historically recorded by TLF in the monitored area. See Table 2. Page 8 of 10 DIGITAL SIGNATURES Page 10 of 10 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 APPENDICES Appendix A: Digital Image Log Appendix B: Field Measurement Data Appendix C: Calibration Data Appendix D: Maps of SEM Results and Satellite Imagery Appendices Page 1 of 13 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 IMG_0015.JPG IMG_0016.JPG IMG_0017.JPG IMG_0018.JPG IMG_0019.JPG IMG_0020.JPG IMG_0021.JPG IMG_0022.JPG IMG_0023.JPG IMG_0024.JPG IMG_0025.JPG IMG_0026.JPG IMG_0027.JPG IMG_0028.JPG IMG_0029.JPG IMG_0030.JPG IMG_0031.JPG IMG_0032.JPG IMG_0033.JPG 10/17/2023 12:08 10/17/2023 12:14 10/17/2023 12:14 10/17/2023 12:15 10/17/2023 12:15 10/17/2023 12:15 10/17/2023 12:20 10/17/2023 12:27 10/17/2023 12:32 10/17/2023 14:28 10/17/2023 14:37 10/17/2023 14:53 10/17/2023 14:56 10/17/2023 14:59 10/17/2023 15:05 10/17/2023 15:06 10/17/2023 15:06 10/17/2023 15:06 10/17/2023 15:07 Taken at the location of exceedance #16. Captures Well EW-97 with sparse, dead vegetation in the vicinity. Taken at the location of exceedance #17, which was noted to have elevated methane readings throughout the swath un unburied waste seen in this image. Image demonstrates a large swath of unburied waste. Established vegetation is growing up through the waste and had been growing long enough to bear fruit. This area was not the active working phase of the landfill at the time of the inspection. Taken at the location of exceedance #18. The area of exceedance #18 was under intermediate cover of wood chips with no vegetation. Taken at the location of exceedance #19. Captures Well EW-61 with no vegetation and some exposed waste in the vicinity. Taken at the location of exceedance #20. Captures Well EW-82C with no vegetation in the vicinity. Some erosion is also visible. Taken at the location of exceedance #21. Captures Well EW-36A with no vegetation in the vicinity. Taken at the location of exceedance #22. Demonstrates the extent of the erosion rill and sparse vegetation at the exceedance point. Exposed waste is also present in the image. Taken at the location of exceedance #23. Demonstrates the extent of the erosion rill and sparse vegetation at the exceedance point. Taken at the location of exceedance #23. Captures several erosion rills in the vicinity of exceedance #23, including a large exposure rill in the center of the image. Fleeting exceedances were noted throughout the area captured in this image. Image also demonstrates sparse vegetation. Taken at the location of exceedance #24. Images demonstrate the extent of erosion, sparse vegetation, dead vegetation, and exposed waste at the exceedance location. Appendices Page 3 of 13 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 EW-89 penetration exceedance. Exceedance recorded at both well 11:21 penetrations and an adjacent PVC 10 AM pipe penetration. The absence of 2900 vegetation, presence of exposed visible waste, and landfill gas odor were noted. 3500 N W - IMG_0009.JPG 39.85549 104.75681 MOV_3339.mp4 11 11:25 Surface exceedance near AM penetration of well EW-90. 1500 2200 N W - IMG_0010.JPG 39.85535 104.75675 Surface exceedance southwest of 11:35 EW-92. The exceedance was 12 AM recorded within a large area of exposed waste with no established vegetation. EW-95 penetration exceedance 11:43 recorded at both well 13 AM penetrations. Absence of vegetation and loosely packed dirt were noted. 900 1200 1200 N W - IMG_0011.JPG 39.85564 104.75614 1200 N W - IMG_0013.JPG 39.85447 104.75613 14 11:49 Surface exceedance in area with AM no vegetation. 1200 1300 N W - IMG_0014.JPG 39.85437 104.75617 11:53 Surface exceedance in area with 15 AM no vegetation, exposed waste, and extensive erosion. 1500 900 N W - DSCN0002.JPG 39.85419 104.75647 EW-97 penetration exceedance 16 12:03 recorded at both well PM penetrations. Absence of vegetation was noted. Multiple surface exceedances recorded in a large area. The area contained a large amount of 12:15 exposed, unburied waste. 17 PM Vegetation was coming up and growing through the exposed waste, indicating the unburied waste had been present for greater than 1-2 months. Surface exceedance recorded in 18 12:23 an area under intermediate cover PM of wood chips. No vegetation was noted. 12:27 EW-61 penetration exceedance. 19 PM No vegetation observed. Exposed waste was also noted in the area. 20 2:25 PM EW-82C penetration exceedance. No vegetation was noted. 650 3500 900 3000 900 800 N W - IMG_0015.JPG 39.85341 104.75663 1500 N W - IMG_0016.JPG -- 39.85371 104.75687 IMG_0021.JPG 1700 N W - IMG_0022.JPG 39.85434 104.75695 1700 2200 N 39.85453 N 39.85138 W 104.75729 W 104.76064 IMG_0023.JPG IMG_0024.JPG Appendices Page 6 of 13 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 EW-36A penetration exceedance 21 2:31 PM recorded at both well penetrations. No vegetation noted. Surface exceedance recorded in an erosion rill with exposed 22 2:50 PM waste visible. Fleeting exceedances were observed throughout the large area in and surrounding the rill. Surface exceedance recorded in an erosion rill with exposed 23 2:52 PM waste visible. Fleeting exceedances were observed throughout the large area in and surrounding the rill. Surface exceedance recorded in a 3'X3' erosion rill. Exceedances greater than 1000 ppm were recorded throughout the rill. 24 3:01 PM Dead vegetation was noted nearby, and a methane concentration of >500 ppm was recorded at the dead vegetation. A strong pervasive landfill gas odor was also noted. Surface exceedance recorded in an area where some erosion and 25 3:06 PM surface disturbance were noted. Some exposed waste was visible, and no vegetation was noted. Exceedance recorded at an unnamed valve penetration. 26 3:08 PM Inspectors noted that there were relatively few gas extraction wells in the vicinity. Surface exceedance recorded at a 27 3:17 PM small rill. The general area had elevated methane levels. No vegetation was noted. 28 3:30 PM EW-72A penetration exceedance. No vegetation noted. 6800 1300 1200 6400 900 1500 1100 12000 7900 N W - IMG_0025.JPG 39.85107 104.76191 900 N W - IMG_0026.JPG 39.8503 104.76164 1400 N W - IMG_0027.JPG 39.85009 104.76181 IMG_0028.JPG 900 N W - IMG_0029.JPG -- 39.84966 104.76201 IMG_0033.JPG 12000 N W - IMG_0034.JPG 39.84926 104.76209 1400 N W - IMG_0035.JPG 39.84961 104.76276 1100 2500 N W - DSCN0003.JPG 39.84892 104.76202 N W - 39.85027 104.76088 IMG_0037.JPG Appendices Page 7 of 13 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 APPENDIX D: MAPS OF SEM RESULTS AND SATELLITE IMAGERY 1. SEM hit locations plotted over satellite imagery from September 4, 2023, as depicted on Google Earth. Approximate monitoring path and monitored areas included (green line and green highlight), derived from GPS data. 2. Detailed view of exceedances on the Northeast portion of landfill Appendices Page 9 of 13 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 3. Detailed view of exceedances on the South-Central portion of landfill 4. Satellite imagery demonstrating exposed waste, separate from the active working face of the landfill, as seen on Google Earth satellite imagery from September 4, 2023. The two smaller green circled areas indicate swaths of unburied waste, as observed by inspectors during the EPA inspection. Appendices Page 10 of 13 Facility Name: Allied Waste Systems of Colorado - Tower Landfill Facility Location: 8480 Tower Road, Commerce City, Colorado 80022 Date of Inspection: October 17, 2023 5. Satellite imagery demonstrating exposed waste near exceedances #5 and #6, as seen on Google Earth satellite imagery from September 4, 2023. This area is also captured in IMG_0002.JPG - IMG_0005.JPG. 6. Satellite imagery demonstrating exposed waste near exceedance #4, as seen on Google Earth satellite imagery from September 4, 2023. This area is also captured in IMG_0001.JPG. Appendices Page 11 of 13