ARCHIVED REPORTS_2010_2 - Laserfiche WebLink

Home Browse Search

4.4.6 Springs During the 1987 geologic/hydrogeologic site investigation, springs were not identified on the site or within one mile of the proposed landfill site 4.4.7 Groundwater Quality 4.4.7.1 Regional Groundwater Quality The NCRC&SL is located within the San Joaquin Hydrologic Region, Eastern San Joaquin Subbasin. The subbasin encompasses 707,000 acres (DWR, 2003). According to California's Bulletin 118 for the San Joaquin River Hydrologic Region, 2003, groundwater quality throughout the region is suitable for most urban and agricultural uses with only local impairments. In addition, groundwater elevations in the Eastern San Joaquin County show a continuous decline over the past 40 years. Because of declining water elevations, poor quality water has been moving eastward along a 16 -mile front on the east side of the Delta. The degradation was particularly evident in Stockton where a saline front was moving eastward. Large areas of groundwater with elevated nitrate are found within the subbasin located southeast of Lodi and south of Stockton. Calcium -magnesium bicarbonate or calcium -sodium bicarbonate types characterize the majority of the basin. Bicarbonate is the predominant anion in the eastern part of the basin. 4.4.7.2 Site Groundwater Quality The groundwater beneath the NCRC&SL does not appear impacted by the presence of the landfill at this time. Groundwater impact has not been detected at the landfill except for one compound detected above trace concentrations at one well (G-4) in one monitoring event (August 2002). The groundwater beneath the NCRC&SL is sampled quarterly in accordance with the WDRs. Quarterly groundwater monitoring reports are submitted to the Central Valley Regional Water Quality Control Board who is responsible for regulating ground water monitoring at landfills. North County RC&SL Page 20 of 69 Public Works/Solid Waste Joint Technical Document County of San Joaquin — February 10, 2010