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Mr.Jadi Singh January 24,2003 Job Number: LE02-481 Page 8 r the various soil layers with a representative of San Joaquin County Environmental Health _ Department. The percolation rate of the soils between the depths of 0 to 3 feet was of interest to our office as explained below. ` With the exception of P-2 which was set at a depth of 3 feet, the percolation tests were set at non- typical depths for a standard type of septic system. Many of the tests were set at depths to determine the extent of the slower percolating surface soil layer,not the standard 3 foot depth for ., a standard leach field. Table 3 presents a summary of the six percolation tests. Table 3. Summary of falling head percolation tests. Test No., Duration Percolation Percolation Rate Soil Type,Comments Date Tested of test Test Depth(ft) (minutes/inch) P-1, 4 hours 1.28 62.4 min/inch Lt.bm.silty f-m sand,loose(SW),slow 11/26/02 percolation rate. r P-2, I hour 3.00 0.98 min/inch Bm f-m sand,dense(w/some silt)(SP), 11/26/02 rapid percolation rate. ` P-3, 4 hours 1.09 25 min/inch Lt bra.silty f-m sand,loose(SW), 11/25/02 moderate percolation rate. P-4, 1 hour 2.00 0.34 min/inch Brn f-m sand,dense(w/some silt)(SP), 11/25/02 Rapid percolation rate.Open hole 6-inch diameter test pit P-5, — 2.08 Very rapid Bm f-m sand,dense(w/some silt)(SP),too 11/25/02 rapid to measure,added 10 gallons,hole ran dry immediately. P-6, 1 hour 3.07 1.11 min/inch Bm f-m sand,dense(w/some silt)(SP), 11/26/02 1 rapid percolation rate. A satisfactory percolation rate is generally considered to be less than 60 minutes per inch for standard septic system leach field trenches. The falling head percolation tests were conducted on the site helped to characterize the soil layers between 1 and 3 feet. The double ring infiltrometer tests were performed to measure the surface soil and the soil located less than 2 feet in depth with a higher degree of accuracy than falling head percolation tests. X1,30 i O A •33 p�1'