COMPLIANCE INFO_JTD 9/3/2025 - Laserfiche WebLink

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Foothill Sanitary Landfill 1 Department of Public Works/Solid Waste First Semiannual 2025 Groundwater Monitoring ©2025 County of San Joaquin. All rights reserved. 1.0 INTRODUCTION 1.1 General This groundwater Monitoring Report for the Foothill Sanitary Landfill (FSL) is submitted in compliance with Central Valley Regional Water Quality Control Board (CVRWQCB) Waste Discharge Requirements (WDR) Order No. R5-2015-0058. The FSL is located in eastern San Joaquin County at 6484 N. Waverly Road, four miles east of Linden, California (Figure 1). Land uses within 1,000 feet of the facility are agricultural, primarily grazing. The vicinity receives an average of approximately 18 inches of precipitation per year. The FSL is a Class III Waste Management Unit (WMU) on an 800-acre parcel, 674 acres of which are planned for waste disposal. This WMU is comprised of: 1) unlined LF-1 (previously designated Module “I” – M-I); 2) lined LF-2; 3) Module 1; 4) Modules 2A and 2B; and future modules to be constructed. Future modules may overlap onto previously completed areas, including LF-1, until final closure of the landfill (Figure 2). The total capacity of the landfill is approximately 116 million cubic yards. The active life of the facility is estimated to allow disposal at least until the year 2103, based on current disposal rates and capacities. The estimated service life will change if actual disposal rates differ significantly than projected rates. Waste discharged to the landfill includes commercial and household waste, construction and demolition waste, and agricultural waste. The rate of disposal during the reporting period was approximately 30,000 tons per month (Table 1). 1.2 Hydrogeology The first water bearing zone encountered is in sandy gravel at a depth of more than 200 feet below the ground surface. Groundwater elevations vary between approximately 30 and 70 feet above mean sea level) and fluctuate less than one foot seasonally. The groundwater is unconfined or partially confined. Above the water-bearing zone, the soil layers are moderately to well-cemented layers of sandstone and siltstone with claystone and conglomerates. This soil is mostly moderately low in permeability with sporadic sandy layers that are well-drained. 1.3 Construction Landfill 1 (LF-1, formerly Module “I”) is an unlined area covering approximately 80 acres. Landfill 2 (LF-2, Modules 1 through 10): Module 1 is provided with composite liner conforming to Resource Conservation and Recovery Act (RCRA) Subtitle D and California Code of Regulations (CCR) Title 27 as follows (from top to bottom):  2-foot-thick soil operations layer