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LIVE OAK GEO ENVIRONMENTAL Surface &Subsurface Contamination Report— The Arbor Mobile Home Park, Acampo June 90, 2009 • 2008 septic repair inspection report indicating that only four of the 2007 seepage pits had been installed. Copies of the EHD records have been included in Appendix 4 of this report. Determination of the Site's compliance status with San Joaquin County agencies is beyond the scope of this report. 116.2 Groundwater Monitoring LOGE reviewed the most recent quarterly groundwater monitoring report4 prepared for the Site. This report, prepared by Provost &Pritchard Engineering Group, indicates that sample collection for the two on-site monitoring wells was not possible for the first quarter of 2009 because the wells were dry;a sample was collected from the off-site well. Since sampling began in 2004, depth to water has been approximately 50 feet below ground surface. The report states that the typical groundwater gradient is to the north. The on-site monitoring well northeast of the septic system shows consistently elevated Ievels of nitrate compared to the other two wells. Levels of nitrate as N in the three wells have ranged from 0.2 to 52.8 mg/L, with recent test results in the 0.2 to 6 mg/L range. The Maximum Contaminant Level (MCL) for nitrate as N is 10 mg/L. Total dissolved solids (TDS) has ranged from 320 to 520 mg/L, and electrical conductivity (EC) has ranged from 316 to 1138 gmhos/cm. LOGE has reviewed only the information provided by FGL; determining whether the water supply to the Site meets all local, State, and Federal regulations is beyond the scope of this report. Portions of this monitoring report have been included in Appendix 4. te" 6.3 Influent and Effluent Monitoring LOGE reviewed the most recent Operations & Maintenance Monthly Report prepared by PERC for the Site's wastewater treatment plant.5 Based on the information presented in this report, it appears that monthly flow, levels of Total Suspended Solids (TSS), and levels of Biological Oxygen Demand (BOD) were within the allowable levels for May 2009. Portions of this report have been included in Appendix 4. 1,"6.4 Drinking Water Monitoring LOGE requested the most recent drinking water sampling results for the Site from FGL Environmental of Stockton, the laboratory handling the sampling and reporting. According to the report, the routine bacteriological sample collected on June 3, 2009 was found to be "invalid." No DBCP was detected in a sample collected between the GAC filters of the water treatment system on June 3, 2009. A sample collected in the same location on August 6, 2008 was found to have 0.08 pg/L (ppb) of DBCP. The MCL for DBCP is 0.2 pg/L. A sample collected from"Well 4" prior to treatment on the same date was found to have 0.90 jig/l, DBCP and 8.9 mg/L (ppm) nitrate as NO3. The MCL for nitrate as NO3 is 45 mg/L. It is not clear whether Well 4 is the currently operating well t 7