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File No. 20-2949-19 kT1 KLEINFELDER November 21, 1991 was measured at approximately 7 to 8-1/2 feet below existing ground surface at locations 2 , 3 and 4 on Plate I, and at a depth of approximately 16 feet at location 5. The difference in water depth appeared to be due to an elevation change between wells. The regional groundwater depth map published by the San Joaquin County Flood Control and Water Conservation District, Plate II, indicates the depth to groundwater in this area was approximately 8 to 10 feet in Spring 1991. Based on County requirements for a small parcel split project, we are not required to establish an on-site groundwater gradient by drilling test borings. We are providing a general estimate of the groundwater gradient based on the published map. Based on the groundwater map showing lines of equal elevation of groundwater, Plate III, we conclude that the main groundwater gradient is in roughly the west direction. ITEM C-5• "Other information as required by the San Joaquin Local Health District to determine the cumulative effect of the existing and the proposed development on groundwater contamination; " This completes our scope of work at this time. Based on the above information, it is our opinion that the two proposed parcels are suitable for septic system use. However, with groundwater at a depth of approximately 7 to 8-1/2 feet, it is possible that if groundwater rises it could reduce the percolation rates of the leach fields. We note that our scope of services did not include a detailed evaluation of the potential for the septic systems to affect the quality of groundwater. However, the project involves only a 10-acre split from the 307-acre property. Therefore, in our opinion, the likelihood of a significant change in the nitrate level of the groundwater beneath the site, due to one additional system, is remote. If additional more concentrated development is planned in the area, we suggest that consideration be given to completing a nitrate loading study. As requested by San Joaquin County Environmental Health personnel , we collected water samples from the on-site well. The samples were delivered to FGL Environmental laboratory in Stockton for nitrate content and DBCP testing. The test results will be submitted under separate cover as soon as the results are received from the laboratory. Copyright 1991 Kleinfelder, Inc. Page 3 of 4