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I File No. 20-3775-01.G02 KLEINFELOER June 30, 1994 r percolation tests at the proposed septic system location were filled with relatively-clean water on June 27, 1994, left to soak overnight, and performed on June 28, 1994. M. STORM DRAINAGE BASIN 1. Subsurface Conditions In general, the materials encountered in the boring drilled at the proposed storm drainage basin k location consisted of approximately 71A feet of sandy clay, with various amounts of gravel, at the surface overlying predominately clayey gravel that extended to a depth of approximately 21'/2 feet. Below that depth, alternating layers of sandy and clayey gravel were encountered and extended to the maximum depth explored of approximately 40 feet. We note.that the sizes and amounts of gravel varied continuously throughout the boring. f No free groundwater was encountered to the maximum depth explored of approximately 40 feet below existing ground surface. We understand that groundwater in the area is somewhere in the vicinity of approximately 150 feet deep. More detailed descriptions of the materials encountered in the boring are presented on the Log of Boring, Plate A-3. All soils have been classified according to the Unified Soil Classification System which is described on Plate A-2. 5 2. Percolation Tests Three percolation tests were performed at the proposed storm drainage basin Iocation on June 27, 1994 by a representative of our firm. Test procedure requires filling the test holes with relatively-clean water to approximately 5 feet above the bottoms. The rate of water level drop in each test hole is then monitored by our personnel for a period of approximately 2 to 4 hours until consistent percolation is achieved. We had difficultymaintaining the desired head of water g in the 10-foot deep test due to highly permeable conditions. We were able to maintain the desired head of water in the 20-foot deep and 30-foot deep tests. The last 10 minutes of each test were used to calculate the following percolation rates in gallons per square foot per day (gfd). BASIN PERCOLATION TESTS Depth Percolation Rate Test No. (feet) (gfd) P-1 8 - 10 Greater than 100 P-2 15 - 20 24 P-3 23 - 30 3 There are many factors that influence storm water disposal. Clean water was used in our tests whereas oil residue, silt, leaves, and/or other deleterious material will likely be included in the Copyright 1994 Deinfelder,Inc. Page 2 of 4