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Report of Findings—Phase 11 Soil a,tca Groundwater Assessment Page 6 Teixeira-Souza Dairy February f,2007 WKA No. 6504.45 Groundwater • Ammonia (as nitrogen) was detected in 14 of the 20 groundwater samples at concentrations ranging from 0.10 milligrams per liter (mg/L)to 3.1 mg/L • Nitrate (as nitrogen) was detected in all 20 groundwater samples at concentrations ranging from 4.6 mg/L to 82 mg/L • Total dissolved solids were detected in all 20 groundwater samples at concentrations ranging from 1,000 mg/L to 2,200 mg/L The U.S. Environmental Protection Agency (EPA) has established a primary Maximum Contaminant Level (MCL) for nitrates at 10 mg/L and a secondary MCL for TDS at 500 mg/L. Groundwater analytical results collected during this assessment identified 15 out of 20 groundwater samples analyzed exceeded the MCL for nitrate as nitrogen and all 20 of the groundwater samples exceeded the secondary MCL for TDS. Currently, there are no regulatory agency guidelines for ammonia in groundwater. The complete analytical testing results, chain-of-custody, and laboratory quality control data for the analyzed soil and groundwater samples are included as Appendix A. The groundwater flow direction and gradient across the site were calculated using surveyed boring location surface elevations and depth-to-groundwater level measurements collected from five of the 20 boring locations. The groundwater flow direction across the site was calculated to be generally to the north at an average gradient of 0.006 feet per foot. CONCLUSIONS AND RECOMMENDATIONS This assessment evaluated soil and groundwater conditions from 20 locations across an approximately 113-acre property previously comprised of the former Teixeira-Souza Dairy. This assessment was conducted in general conformance with the tentative WDR recently issued by the RWQCB with the purpose of providing a baseline of soil and groundwater conditions after completion of dairy demolition activities. �X` �\\ =