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r Soil Suitability&Nitrate Loading Study Page 8 St.Patrick's Church,Escalon, CA Project No- 607.1 r August 31, 2009 6.0 PERCOLATION TEST North American Technical Service (NATS) conducted a percolation test on August 20, 2009 under the supervision of the San Joaquin County ' Environmental Health Department and using EHD guidelines. The agency defines a shallow percolation test as between 36 and 42 inches, while a deep percolation test is between 42 inches and 25 feet. In this case, a shallow test ` was deemed appropriate by the agency. A test percolation rate of less than 60 minutes per inch for a shallow test, or less than 30 minutes per inch for a deep Ftest is considered a "passed" test, meaning that a standard design septic system is acceptable. The test is to be made within the "footprint" of the proposed new leach field. F 6.1 Test Description On August 18, 2009 a 6-inch diameter soil boring was advanced to a depth of 42 inches using truck-mounted drilling equipment owned and operated by NATS. An approximately 2-inch thick layer of "pea-gravel" was placed at the bottom of the boring, and a 4-inch diameter PVC temporary casing perforated at the bottom was place over the gravel pad. The annulus between the casing and the boring was then partially filled with pea-gravel. The PVC casing was used to measure the decreasing water level in the boring. r In the 24 hours prior to completing the test, the boring was pre-soaked. The packed boring was filled with water to a depth of 12 inches. The percolation test was completed in accordance with EHD requirements and } under the supervision an EHD representative on August 19, 2009. The duration of the test was four hours. An electronic well sounder with an accuracy of 0.01 feet was used to monitor the fall of water during the test from a fixed point of F reference. 62 Test Results The percolation test yielded a percolation rate7f83.3 nutes per inch. This compares with the minimum acceptable rate o -minutes per inch for a standard-design septic system The soil at the site of the test was a sandy loam, which would be expected to yield a more rapid percolation rate than that actually recorded. It was noted that that a cornfield lying only about 6 feet from Fithe test hole had been recently irrigated and the soil appeared to be totally saturated. This is believed to have materially reduced the observed percolation rate. E+ 2937 VenemanAve.,#B240 Geo-Phase Environmental Inc. Phone: (209) 569-0293 Modesto, CA 95356 Fax: (209) 569-0295