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Home My WebLink About8003_RowanCountyMSWLF_ASDResponse_DIN27041_20161122 PAT MCCRORY Governor DONALD R. VAN DER VAART Secretary MICHAEL SCOTT Director State of North Carolina | Environmental Quality | Waste Management Asheville Regional Office | 2090 US Highway 70 | Swannanoa, NC 28778 828 296 4500 T November 22, 2016 Sent Via Email - Caleb.Sinclair@rowancountync.gov Mr. Caleb Sinclair Rowan County 1102 N. Long Street Extension Salisbury, NC 28144 Re: Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28 Rowan County Landfill Rowan County Solid Waste Permit Number 8003 DIN 27041 Dear Mr. Sinclair: The North Carolina Department of Environmental Quality’s Solid Waste Section has completed a review of the Alternate Source Demonstration To Address Anamalous Volatile Organic Constituents at MW-28 dated June 10, 2016 (DIN 26384), the Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28 dated September 23, 2016 (DIN 27038), the Water Quality Monitoring Report, 2nd Semiannual 2016 Sampling Event dated October 13, 2016 (DIN 27039), and the Methane Monitoring Results-4th Quarterly Event October 2016 dated October 20, 2016 (DIN 27040). All four documents were submitted on behalf of Rowan County by Golder Associates for the Rowan County Landfill, Solid Waste Permit Number 8003. The Alternate Source Demonstration To Address Anamalous Volatile Organic Constituents at MW-28 and the Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28 were submitted in accordance with 15A NCAC 13B .1633(c)(3) and in response to the presence of the volatile organic compounds, Tetrachloroethene (PCE) and Trichlorofluoromethane (TCFM), in samples within groundwater monitoring well MW-28. The Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28 was also submitted in response to the Solid Waste Section letter dated June 30, 2016 (DINs 26385 and 26386). The volatile organic compounds, Tetrachloroethene (PCE) and Trichlorofluoromethane (TCFM), were present in all four baseline groundwater monitoring events for Phase IV, and they continue to be a concern within groundwater monitoring well MW-28. During the most recent August 2016 monitoring event, PCE had a concentration of 2.8 micrograms per liter (ug/L) and that exceeds the NC 2L groundwater standard of 0.7 ug/L, and TCFM had a concentration of 0.66 ug/L and that did not exceed the NC 2L groundwater standard of 2,000 ug/L. Per the Water Quality Monitoring Report, 2nd Semiannual 2016 Sampling Event, groundwater monitoring well MW-28 is 26.2 feet deep with a 15 foot screen, and the proposed replacement well for MW-28 is MW-6 which has a total depth of 53.7 feet with a 5 foot screen. That well is located approximately 400 feet east-northeast of MW-28. Groundwater monitoring well MW-6 only had a detection of Barium during the most recent sampling event. Currently, the landfill does not have a landfill gas extraction system. During the most recent October 2016 quarterly landfill gas monitoring event for the landfill, methane gas exceedances were recorded within MMW-3, MMW-6, and MMW-8. To address landfill gas as a potential source of groundwater contamination within groundwater monitoring well MW-28, two summa canister samples were collected from the headspaces of landfill gas monitoring well MMW-8 and groundwater monitoring well MW-28. The analytical results indicated that acetone was detected in both samples. Acetone is a common liquid leachate constituent at landfills. Based upon the semiannual leachate sampling results (for L1) since 2006, acetone has been detected from concentrations ranging from non-detect to 2000 ug/L at the landfill. Other constituents not detected within the groundwater samples were detected within the headspace gases within both monitoring wells. The headspace analytical results indicate the following constituents detected above the laboratory’s method detection limit within landfill gas monitoring well MMW-8: 2,2,4- Trimethylpentane, Acetone, Cyclohexane, Dichlorodifluoromethane, Freon 114, Heptane, n-Hexane, Total Light Hydrocarbons, and Vinyl Chloride. In addition, the analytical results indicate the following constituents detected above the laboratory’s method detection limit within groundwater monitoring well MW-28: 1,2-Dichloroethane, 2-Butanone,2-Propanol, Acetone, Carbon Disulfide, Ethyl Acetate, Tetrachloroethene, Toluene, and Total Light Petroleum Hydrocarbons. It was further noted within the laboratory analytical report that the headspace samples were diluted (dilution factor up to 58) in the laboratory. To address any concerns regarding the 2007 leachate release in the area near groundwater monitoring well MW-28 as a potential source, a reference was made to the report titled Acetone Assessment Report Addendum dated January 2008. Per the Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28, “the conclusions of this report were that soil and groundwater sampling results performed to date did not indicate a release of leachate in the area investigated and that no further assessment is warranted. Volatile organic compound impacts to soil or groundwater discovered during the 2007 investigation were minimal and none could be linked directly to a leachate release, therefore, this does not appear to be a likely source of volatile organic compounds at MW-28.” The matter concluded in 2009 based upon the March 12, 2009 Solid Waste Section letter to the County that stated that the temporary groundwater piezometers were approved to be abandoned at that time (DIN 7012). To address the location of the leachate collection components relative to groundwater monitoring well MW-28 as a potential source, per the Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28, “force mains from Phases 1, 2, 3, and 4 were designed and constructed with double containment, and therefore, because the leachate system components have dual containment and are generally sidegradient with respect to MW-28, leachate from the containment system is not a likely source of VOCs at MW-28.” Finally, to address former land uses as a potential source, historical aerial photographs were used depicting the area near groundwater monitoring well MW-28. Based upon the aerial photographs, the landfill property was used for agricultural activities from the 1940s to the 1980s. Also based upon historical knowledge, the area of concern was once utilized as a white goods storage area for approximately ten years, and also a contractor laydown and fueling/equipment maintenance area for two landfill construction projects. As a result, based upon the information provided within the Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28, the Response to Comments Alternate Source Demonstration To Address Anomalous Volatile Organic Constituents At MW-28, the Water Quality Monitoring Report, 2nd Semiannual 2016 Sampling Event, and the Methane Monitoring Results-4th Quarterly Event October 2016, the Solid Waste Section does not approve the alternate source demonstration for the landfill at this time. Rowan County has failed to demonstrate that the increase in the constituent concentrations are the result of a source other than the MSWLF unit in accordance with the US EPA’s November 1993 Solid Waste Disposal Facility Criteria Technical Manual. Therefore, in accordance with 15A NCAC 13B .1633(c)(3) and 15A NCAC 13B .1634, Rowan County is required to initiate an Assessment Monitoring Program for this landfill within 90 days of receipt of this letter. Also, groundwater monitoring well MW-6 is not approved as a replacement well for MW-28 at this time. If you have any questions regarding this letter, please feel free to contact me at 828-296-4706 or by email at jaclynne.drummond@ncdenr.gov. Thank you in advance for your anticipated cooperation with this matter. Sincerely, Jaclynne Drummond Compliance Hydrogeologist Solid Waste Section, Division of Waste Management NCDEQ cc sent via email: Greg Greene, Rowan County Jeff Boyd, Rowan County Jason Watkins, Field Operations Branch Head Deb Aja, Western District Supervisor Kim Sue, Senior Environmental Specialist Ed Mussler, Permitting Branch Head Perry Sugg, Permitting Hydrogeologist Ming Chao, Permitting Engineer