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<br />North County Recycling Center & Sanitary Landfill Public Works/Solid Waste <br />First Semiannual 2024 Groundwater Monitoring 2 ©2024 COUNTY of San Joaquin. All Rights Reserved. <br /> <br />an elevation of approximately 88 feet NAVD 88, which is approximately 30 feet below original <br />grade. This Area is provided with a 60-mil HDPE liner installed over a 6-inch (minimum) thick <br />layer of compacted native soil. NCRC&SL was not designed to meet Title 27 and RCRA Subtitle <br />D criteria since these regulations were not in effect at the time of construction. <br />Lined Area 3 was constructed in 1995, excavated to an elevation of approximately 60 feet NAVD <br />88, which is approximately 60 feet below original grade. This area is provided with a composite <br />liner comprised of a geocomposite clay layer (GCL) under a 60 mil HDPE membrane. This liner <br />design was approved as an engineered alternative to the prescriptive composite liner of Title 27 <br />and RCRA Subtitle D. <br />The interface between Areas 1 and 3 is composed of an anchor trench/berm at an elevation of <br />approximately 96 feet NAVD 88. <br />Lined Area 4 was constructed in 2003, excavated to a depth of approximately 60 feet NGVD, <br />which is approximately 60 feet below original grade. This Area is also provided with a composite <br />liner comprised of a GCL under a 60-mil HDPE membrane as an approved engineered <br />alternative to the prescriptive composite liner of Title 27 and RCRA Subtitle D. In addition, a one- <br />foot thick layer of soil with not less than 30% passing 200 sieve, compacted to not less than 90% <br />relative density, was constructed under the composite liner. <br />The interface between Areas 3 and 4 is a lined anchor trench/berm, raised approximately three <br />feet above the surrounding surfaces. <br />Area 5A containment cell was designed and constructed according to the requirements of <br />Title 27, RCRA Subtitle D and North County’s WDR. <br />The base and side slope liners of Area 5A were joined to the existing Area 4 base and side slope <br />liners. The base liners of Area 4 and Area 5 were tied at Elevation 70 NAVD. The base of Area 5 <br />transitions from Elevation 70 to 68 NAVD with a 3:1 slope, then slopes towards the west with a <br />2% cross slope. <br />Area 5B construction was completed end of November 2017. The CQA report was submitted on <br />December 15, 2017, to the Central Valley Regional Water Quality Control Board (Regional <br />Board) and was approved on January 16, 2018. The County is currently placing waste in Area <br />5B. Construction of Module 6 was completed in November 2022. Extreme winter precipitation <br />caused heavy erosion to the slopes which had to be repaired in spring/summer. Upon completion <br />of repairs a CQA report was submitted to the Regional Board for review and approval. Approval <br />of the CQA report was received on August 17, 2023. Waste placement began in Module 6 <br />immediately thereafter to establish a base layer to shed precipitation expected from the 2023- <br />2024 rainy season. <br />COMPLIANCE SUMMARY <br />Data from the groundwater wells at the North County Landfill did not indicate impact until five <br />volatile organic compounds (VOCs) were confirmed at low concentrations in well G-4 in July <br />2002. Due to the close proximity of G-4 to the western property boundary, County staff contacted <br />the neighbor immediately to the west, requesting permission to drill temporary groundwater