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z -gig :4z SAN.HAQUIN <br />n Cr; <br />-------COUNTY - <br />Ae4l� <br />Wadft for YOU <br />August 28, 2017 <br />Mr. Howard Hold, PG <br />Senior Engineering Geologist <br />Central Valley Regional Water Quality Control Board <br />11020 Sun Center Drive, Suite #200 <br />Rancho Cordova, CA 95680 <br />Department of Public works <br />Kris Balaji, Director of Public Works <br />Fritz Buchman, Deputy Director/Development <br />Michael Selling, Deputy DirectorlEngineering <br />Jim Stone, Deputy DirectorlOperations <br />Najee Zarif, Interim Business Administrator <br />RE: NOTICE OF VIOLATION OF THE SECOND SEMESTER AND ANNUAL 2016 <br />GROUNDWATER AND SURFACE WATER MONITORING REPORT FOR THE FOOTHILL <br />SANITARY LANDFILL, SAN JOAQUIN COUNTY <br />Dear Mr. Hold: <br />San Joaquin County, Public Works Solid Waste Division, is in receipt of the Notice of Violation from <br />the Central Valley Regional Water Quality Control Board (CVRWQCB) dated July 11, 2017 regarding <br />the following items at Foothill Sanitary Landfill: <br />• Volatile organic compounds in soil gas probes <br />• Volatile organic compounds in groundwater monitoring well MW -3 <br />• Requirement to convert probes SG -4, 5, 7, and -9 from single level probes to multi-level <br />probes. <br />As detailed in the Well Installation Report dated November 2, 2016, San Joaquin County (County) <br />installed, adjacent to Landfill -1 (LF -1 aka Module 1), five (5) tri -level monitoring probes, namely SG -2A, <br />SG -3A, SG -6A, SG -10A, and SG -11A, to convert former single level probes to multi-level probes to <br />assist with the assessment of landfill gas (LFG) migration. Additionally, at Module I, the County installed <br />four (4) additional LFG extraction wells namely GX-10, GX-11, GX-12, and GX-13 in July 2016. These <br />probes and wells were put into service in late 2016 and have been monitored in 2017. Early data on <br />the new wells indicates the presence of significant quantities of LFG that can now be recovered from <br />waste areas previously contributing to LFG migration. <br />Whilst VOCs continue to be detected in probes and in well MW -3 in 2017, it is well documented in the <br />semi-annual groundwater monitoring reports compliance history that there is an expected lag of three <br />to five years for the effects of landfill gas system corrective actions on site groundwater remediation as <br />observed at MW -3. The County and its consultant, APTIM (formerly known as CB&I), do not expect the <br />effects of the LFG extraction wells; activated in late 2016; to have an effect on groundwater for at least <br />two (2) or more years. To complicate matters, Foothill Landfill, and California in general, received an <br />unusual amount of rainfall in 2016-2017. The average rainfall for the previous five (5) years in the <br />Foothill Landfill area was only 7.95 inches. Between October 2016 and April 2017, the area received <br />over 18 inches of rainfall. The effects of the rainfall in terms of landfill gas production have not only <br />been witnessed at Foothill, but also throughout the State at other landfills. The LFG well field at Module <br />I went from a historically "over -pulled" condition (LFG wells under 50% methane in most wells) to and <br />"under -pulled" condition (LFG wells with over 50% methane). The well field operator (SCS) and power <br />plant operator (Ameresco) have agreed to make adjustments to the well field gas extraction and flare <br />operations to compensate for the increase in landfill gas generation from the winter rains. <br />1810 East Hazelton Avenue 1 Stockton, California 95205 1 T 209 468 3000 1 F 209 468 2999 <br />