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• CONCLUSIONS <br /> Based on the method and assumptions described, the result of the nitrate loading <br /> estimate indicates that proposed development on the Site has the potential to cause a <br /> buildup of nitrates in the aquifer of 14.6 mg/L-N, above the MCL of 10 mg/L-N. <br /> The depth of ground water based on recent aquifer levels is estimated to range from <br /> 105 to 115 feet below ground surface, depending on the season. The ground-water <br /> flow appears to vary significantly depending on season; in the spring, the flow direction <br /> and rate are unclear, while in the fall the flow is to the north-northwest at a rate of <br /> approximately 10 feet per mile. <br /> A water sample was collected from the domestic well on the Site. Nitrate was detected <br /> in the sample at a concentration of 7.6 mg/L-N, below the MCL of 10 mg/L-N. <br /> Because of the result of the nitrate loading calculation, the San Joaquin County <br /> Environmental Health Department will likely require annual monitoring of the new <br /> domestic well for nitrate. The purpose of this monitoring is to determine whether nitrate <br /> levels in the ground water are increasing. <br /> No other nitrate mitigation measures are being required by the San Joaquin County <br /> Environmental Health Department at this time. However, since the construction of new <br /> • septic systems is planned, the owner has the opportunity to modify the septic systems <br /> to reduce nitrate levels in the effluent. Simple septic system modifications that have <br /> been employed for other projects in San Joaquin County include installing oversized <br /> septic tanks and adding additional carbon, such as wood chips, to the leach lines. The <br /> San Joaquin County Environmental Health Department has indicated that these <br /> modifications promote additional nitrogen reduction which may result in a lessened <br /> impact to the aquifer. Additionally, the costs of these modifications are minimal <br /> compared to the potential long-term benefit. If modifications to the system are desired, <br /> the septic contractor should contact the San Joaquin County Environmental Health <br /> Department for direction. <br /> • LOGE 1833 Page 9 <br />