ARCHIVED REPORTS_2007 - Laserfiche WebLink

Home Browse Search

INTRODUCTION General On behalf of San Joaquin County(County), Shaw Environmental Inc. (Shaw)has prepared this second quarter 2007 monitoring report for the Corral Hollow Sanitary Landfill (CHSL) in compliance with Waste Discharge Requirements (WDR) Order No. 5-01-176 issued by the California Regional Water Quality Control Board, Central Valley Region, on June 14, 2001. The Corral Hollow Landfill is located at 31130 South Corral Hollow Road, in southern San Joaquin County, approximately 5 miles south of the City of Tracy, at the intersection of Interstate 580 and Corral Hollow Road. The landfill is located in Township 3 South, Range 5 East of Section 18 on the Mount Diablo Meridian. This landfill is a closed, unlined Class III landfill. The landfill property includes approximately 58 acres, of which 43 acres was permitted to receive refuse(Figure 1). The remaining area is comprised of access roads, storm water retention ponds, setbacks for environmental monitoring, and firebreaks. Land within 1,000 feet of the facility is used for grazing and agriculture. The landfill ceased receiving waste in 1991. A final cover was constructed in the fall of 1995 in compliance with Order No. 94-259. The closure cover consists of a 2 to 6-foot foundation layer under a 1-foot minimum thick, low-permeability soil layer, with a 1-foot thick vegetative surface layer. A landfill gas collection system was installed and began operating in December 2001. Geologyand H dro eolo Y g g3' Surface soils at the site are typically sands and gravels to a depth of about 70 feet, underlain by low permeability silts and clays to 150 feet. Sands and gravels predominate to a depth of approximately 430 feet. Highly impermeable sandy clays are present at 430 feet. The h ro eolo at the site is complex. A dee aquifer is found at an elevation of Yd g gY P p q approximately-45 to -57 feet (MSL), at a depth of between approximately 299 and 357 below the surface. Groundwater flows in the deep aquifer to the northeast. A shallow aquifer is found beneath the northeast and east side of the landfill property due to the presence of the Corcoran Formation, which rises from the northeast, apparently intercepting the landfill base. This aquifer is unconfined, and mounds near monitoring well SB-l. The elevation of this shallow aquifer is approximately 230 feet MSL. Depth to this shallow aquifer varies between 12 and 65 feet below existing grade(depth variations result from variations in the surface elevations). Attempts to locate and monitor the shallow aquifer south and east of the landfill footprint in 2003 indicated that this aquifer is inconsistent in elevation, and discontinuous within the landfill property. The Corcoran Formation, and the associated shallow aquifer, is not found beneath the southwest side of the landfill. Corral Hollow Landfill I Department of Public Works/Solid Waste 2n°Quarter 2007 Groundwater Monitoring County of San Joaquin—July 31,2007