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Soil Suitability&Nitrate Loading Study Page 9 Proposed Oak Farm Vineyards Expansion,Lodi CA Project No. 670 IC June 17.2013 6.0 PERCOLATION TEST Two separate percolation tests were conducted under permit of the San Joaquin County Environmental Health Department and using EHD guidelines. An agency representative was notified in advance of the tests. 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 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 test is considered a "passed" test. The test is to be made within the "footprint"of the proposed new leach field. 6.1 Test Description The first percolation test occurred on March 15, 2013- North American Testing Service (NATS) installed 6-inch diameter soil borings to depths of 42 inches and 66 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 each 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. In the 24 hours prior to completing the test,the borings were pre-soaked. The packed boring was filled with water to a depth of 12 inches. The duration of the test was four and a half 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 reference. Neither of these tests yield acceptable percolatipn rates. On May 28, 2013,a second percolatiop test was conducted by Live Oak Geo Environmental, Inc. of Lodi. A 4-inch--diameterboring was advanced by hand auger to a depth of about 39 inches and was completed for the percolation test Approximately one inch of pea gravel was placed in the bottom of the open soil boring, followed by a 1.5-inch diameter PVC pipe with perforations on the bottom. Pea gravel was then used to backfill a few inches of the annular space. The test boring was pre-saturated for approximately 24 hours prior to the percolation test. The hole was filled with water to a height of 12 inches above the bottom of the boring for the pre-saturation. On the day of testing, the shallow hole was found to be intact and dry. A 4-hour test was conducted in the presence of the County inspector. 6.2 Test Results The County Environmental Health Department defined a percolation test between 36 and 42 inches as a "shallow" test. The percolation test in the shallow (39") boring yielded a percolation rate of less n 4.88 mutes per inch, as compared to the minimum acceptable rate of 60 minutes per inc . ed on the test results and the EHD Sewage Standards, the — percolation test was successful with respect to use of standard septic system design. Copies of both percolation test reports are attached as Appendix C. 2937 Veoeman Ave.,#B240 Ce Mase Environmental Inc. Pbone: (209)569-0293 Modesto,CA 95356 Fax: (209)569-0295