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Ratto, Sarale and Del Carlo Property Page 3 of 9 Our Project Number: LGS080506 May 30, 2008 3.6 Septic Repair Permit History in the Vicinity Based on a recent file review at the EHD, the septic repairs in the vicinity appear to be for the , addition of leach lines. The septic repair permits can be found in the back of this report. 3.7 Expected On-Site Maximum Septic Tank Usage Maximum expected usage on each proposed parcel would be for a primary residence and / second dwelling unit. Septic system design should be based on the On-Site Wastewater Disposal Standards or other engineering recommendations. 4.0 GROUNDWATER INFORMATION 4.1 Groundwater Depth and Gradient As previously mentioned in Section 1.1, the elevation of the Site lies between 0 and 10 feet above mean sea level. The San Joaquin County Flood Control and Water Conservation District (2003 and 2004) groundwater elevation maps were reviewed to determine the groundwater el a:sea s r the Site. The Fall 2003 and Spring 2004 maps are the most current official �pailable om the County. According to these maps (Plates 3 and 4), groundwater lies nearlevel d flows at an Cindeterte direction in the vicinity of the Site. Grouater was encounterellin by the staff of Neil 0. Anderson and Associates, Inc. at a depth of approximateee, below ground surface. 4.2 Potential Groundwater Contamination Issues Identifying potential groundwater contamination sources was not part of the scope of work for the soil suitability study. Potential groundwater contamination can occur from a number of sources which often include leaking underground storage tanks, agricultural activities, dairies, septic systems, and storm water infiltration. Agricultural activities and the use of septic systems in the area should be considered potential groundwater contamination sources. 4.3 Water Sample Location r. 1 One Vvell exists on the Sit permits v ere found during a recent file review at EHD. A well water Sample was taken n ay 8, 2008 by Jessen Welch from the spigot of the domestic well on the Site. 4.4 Water Sample Constituents The ter sample was anal�ed rof rof hAT-ate and DBCP. DBCP as not d tected in the water ampl . Nitrate was found at 2.9 mg/L-N'03, below the maximu conta inant level (MCL) of 45 /L-NO3 set by the1ll�ted__States EPA. The analytical epo prepared by FGL En ' onmental can be found in the appendix of this report. Ratto, Sarale and Del Carlo Property Page 4 of 9 Our Project Number: LGS080506 May 30, 2008 Well construction, seals, age and depth of the well screens may play significant part in assessing the levels of Nitrate and DBCP in various aquifers. Without knowing specific details regarding well construction and condition, it would be difficult to accurately comment on the condition of the aquifer. Essentially, the water sample concentration approximately indicates the contaminant concentration level of the aquifer from which the well is drawing. It is Neil 0. Anderson and Associate's opinion that, in general, near surface aquifers are more likely to have elevated concentrations of Nitrate and DBCP than the deeper aquifers. However the contaminant concentration of one aquifer cannot give any indication as to the concentrations of any other aquifer regardless of proximity. The presence of nitrates is not uncommon in shallow groundwater aquifers in San Joaquin County and other parts of the Central Valley. Nitrate in groundwater 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 groundwater zones. In the early 1900s, natural levels of nitrate in groundwater were measured in forty-three (43) wells throughout the Sacramento Valley by Kirk Bryan (1923). It was thought that groundwater at that time was close to "natural" conditions. Based on the work of Bryan, it is estimated that under "natural" conditions, the groundwater concentration of nitrate is no more then about 13.5 mg/L-NO3 (3 mg/L-N). Areas having 24.75 mg/L-NO3 (5.5 mg/L-N) or more are those in which nitrate concentrations may be increasing (Hull, 1984). DBCP was not detected in the water sample. DBCP is a nematocide and soil fumigant for vegetables and grapes. It is thought to cause health problems consisting of kidney damage, liver damage, and cancer. The use of DBCP was discontinued in 1979. The Environmental Protection Agency (EPA) set the maximum contaminant limit (MCL) at 0.2 parts per billion (ppb) because the EPA believes that given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water. 4.5 Well Water Sample Collection, Handling, and Transportation The sample for nitrate was collected in a sterile plastic container; the sample for DBCP was collected in two sterile glass vials. The samples were then transported on ice and remanded under chain of custody to FGL Environmental, Stockton. 4.6 Chain of Custody The Chain of Custody document has been included in the appendix of this report. ,-44 902 Industrial Wav•Lodi,CA 95240-209.367.3701 •Fax 209.369.4228 02008 Nei!O.Anderson&Associates.Inc