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File No. 20-3551-01 W� KLEIVFEL>7ER January 27, 1992 remaining three tests performed at depths treater than 3 feet passed with percolation rates of 2-1/Z--to 30 min/in D The percolation test results are summarized in Table I, below. The County approved percolation test sheets are included with this report. k TABLE I i PERCOLATION TEST RESULTS Depth Percolation Rate Test No. Lot No. feet min in P-1 13 9-1/2 o- 2-1/2 � $ P-2 16 8 3 0 12 t P-4 3 3_1/2 6 0 1"j, ".c' } We note that prior to final approval for construction, the County will require a passing percolation test be obtained on each lot. ITEM C-3 : t "The depth and gradient of the water table;" During our residence surveys on January 15, 1992, we were able to measure groundwater in one well. The groundwater was measured at approximately 145 feet below existing k ground surface in a well southwest of the site (location 4 f on Plate I) . We were informed that groundwater was recently measured at a depth of approximately 196 feet in t the private well located on Lot 11. The difference in y depth to water in the two wells appeared to be mostly due to topography. 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 140 to 145 feet in Spring 1991. Since groundwater is greater than 65 feet deep beneath the site, 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 south-southwest direction. A 4. Copyright 1992 Kleinfelder, Inc. Page 3 of 4