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A shallow percolation test is defined by the EHD as being between 36 and 42 inches in depth. A deep percolation test is defined as being between 42 inches and 25 feet in depth. A satisfactory percolation rate for a shallow test is less than or equal to 60 minutes per inch drop. A satisfactory percolation rate for a deep test is less than or equal to 30 minutes per inch drop. Either one shallow or deep test must demonstrate a satisfactory percolation rate within the proposed septic system disposal field. A summary of the percolation tests is presented in Table 1. 6.6 Complete Percolation Test Form (including readings) was provided with REHS verification signature. The rate was correctly calculated using the last reading. See Appendix for Test Results Form. Table 1 Summary of Percolation Tests Test No. Date Tested Percolation Test Depth ft Percolation Rate minutes/inch Test Duration Comment See notes PT 3.11' shallow, 4-20-04 3.11 --- 4 hr Not evaluated PT8.70' deep, 4-20-04 8.70 --- 4 hr Not evaluated PT 3.20' shallow, 4-20-04 3.20 No movement 4 hr Failed PT 24.0' deep, 4-20-04 24.00 8.06 4 hr Satisfactory Percolation rate FUI %�U,A«U,, , ULC ivr a suauow- test is less Yuan or equal to 6u minutes per inch. A satisfactory percolation rate for a "deep" test is less than or equal to 30 minutes per inch. 6.7 Discussion of any potential problems predicted and/or the need for an engineered or alternative septic system. In this area, the soils are classified as San Joaquin Loam. Due to this classification and percolation rate, a standard septic system including pits would be sufficient on the proposed parcels. Given the proposed improvements plan to have three (3) additional modular buildings an engineered system may be preferred. The EHD sewage standards should be followed to size septic systems. 6.8 Discussion of percolation rates in relation to the type, size and location of future leach fields needed at the site. Based on the results of the percolation rates and the soils profile, it is Dillon & Murphy's opinion that the subject proposed parcel is suited for a typical on-site sewage disposal system, but an engineered system should be preferred. The systems should be properly designed and installed according to the current San Joaquin County criteria for standard septic systems. Based on the depth to groundwater in the area, and the size of the proposed parcel, it is our opinion on that the installation of any new proposed septic system, if property installed, should not adversely affect the quality of groundwater in the area. 0