SU0004662 SSNL - Laserfiche WebLink

Home Browse Search

August 3, 2004 NOA Project Number: E04081A 4.3 Potential Ground Water Contamination Issues Identifying potential ground-water contamination sources was not part of the scope of work for the soil suitability study. Potential ground-water contamination can occur from a number of sources which often include leaky underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Any past agricultural activities and the present use of septic systems in the area should be considered potential ground-water contamination sources. It should be noted that a water treatment facility is located less that one mile northeast of the Site. 4.4 Well Water Sample Location Three water samples were collected from an outside faucet fed by the on-site domestic water well on July 14, 2004 by Ms. Abigail Racco of our office. The locations of the well and water sample are indicated in Plate 1. _ 4.5 Well Water Sample Collection, Handling, and Transportation The samples were collected in a clean plastic container, then decanted into clean, glass vials. The samples were then transported on ice and remanded under chain of custody to Precision Enviro-Tech, Stockton. The Chain of Custody document has been included in the appendix of this report. •�4.6 Well Water Sample Analytical Results Nitrate was found at 11.3 -Nn3, well below the maximum contaminant level (MCL) set by the United States Environmental Protection Agency (EPA) of 45 mg/L-NO3. DBCP was _ found at 0.08 /L, well below the EPA MCL of 0.2 µg/L. The analytical reports prepared by Precision iro-Tech can be found in the appendix of this report. The presence of nitrates is not uncommon in shallow ground water aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in ground water occurs as a result of the application of fertilizers, livestock waste, and untreated septic tank waste. Nitrate is mobile and often accumulates in the shallow ground water zones. In the early 1900s, natural levels of nitrate in ground water were measured in forty-three (43) wells throughout the Sacramento Valley by Bryan (1923). It was thought that ground water at that time was close to "natural" conditions. Based on the work by Bryan, it is estimated that 7