SR0082147 SSNL - Laserfiche WebLink

Home Browse Search

Clayey soils, like those found on the Site, are known to restrict downward movement of water, and may provide nitrate reduction through adhesion to the soil particles. Groundwater Analysis Depth and Gradient Live Oak reviewed ground-water elevation information available from the San Joaquin County Flood Control and Water Conservation District to determine the ground-water levels near the Site. Data from the spring and fall of 2016 were the most recent available from this source (Plates 6 and 7). According to an analysis of these maps, the ground-water elevation is approximately 35 to 43 feet above mean sea level, depending on the season. The ground-water flow is to the north or northeast at a rate of approximately seven to ten feet per mile, depending on the season. Given that the ground elevation of the Site is approximately 75 feet above sea level, based on the County ground water maps the depth to ground water below the Site is estimated to range from 32 to 40 feet. San Joaquin County experienced its highest recent ground-water levels in 1983 and 1999. Maps of spring ground-water levels were reviewed for this study (San Joaquin County Flood Control and Water Conservation District, 1983 and 1999); however, the Tracy area is not mapped for these years. Potential Ground Water Contamination Issues The Nitrate Loading Study is not intended to be an investigation into ground-water contamination sources, and no such investigation was conducted. Many sources can contribute to ground water contamination, including leaking underground storage tanks, agricultural activities, dairies and cattle ranches, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area are known ground-water contamination sources with the potential to impact the Site. Live Oak is aware that the Site is located approximately 360 feet north of the former Trinkle and Boys crop dusting facility, which operated from 1949 to 2001. The Trinkle and Boys property is known to have been the site of improper pesticide storage practices, as well as former underground gasoline storage tanks. Ground-water contamination was detected in a 2008 investigation, though subsequent monitoring did not identify ground-water contamination. In 2012, the Central Valley Regional Water Quality Control Board issued a "no further action" letter for the facility based on a human health risk analysis of the constituents detected. Live Oak is also aware that the Site is located approximately one-third of a mile from George's Service and New Jerusalem School, two additional sites of environmental LOGE 20-21 Page 3