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k" KLEINFELDER File No. 20-3478-01 May 15, 1991 Page 2 of 3 No one was home at four of the residences visited. However, the three residents questioned reported having no problems with the performance of their septic systems. The septic systems were reported to be between approximately 10 to 20 years old. All of the residents questioned indicated that their wells produced "good" quality water. ITEM C-2 • "Suitability of soil for development utilizing septic systems. " On April 25 and May 2 , 1991, representatives of our firm drilled and set-up 3-foot deep percolation test holes on each of the proposed parcels. The test holes were drilled with hand drilling equipment using a 6-inch diameter continuous-flight auger. Perforated PVC pipe was inserted into the test holes to prevent disturbance when adding water. The test holes were filled with relatively clean water the day before testing and were left to soak overnight. On April 26 and May 3 , 1991, our representatives returned to the site to perform the 3-foot deep percolation tests. As per San Joaquin County guidelines, the tests were performed for a period of 4 hours. The last 30 minutes of each test were used to calculate the percolation rates. In order to use standard leach lines, the County requires a percolation rate of 60 minutes per inch, or faster, at the 3-foot depth. The 3-foot deep tests performed passed with percolation rates of 30 and 17-1/2 minutes per inch for the proposed 1-acre and 1-1/2-acre parcels, respectively. The County approved percolation test sheets are included with this report. ITEM C-3• "The depth and gradient of the groundwater table. " During our residence surveys on April 22 , 1991, we were able to measure groundwater in six wells. The groundwater was measured at depths of approximately 106 to 108 feet below existing ground surface. 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 110 feet in Spring 1990. Based on County requirements for a parcel split project such as this, 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 Copyright 1991 Kleinfelder, Inc.