1978-02-13 Septic System Design Report

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78-08B Mr. David Nitz Test N P-11 P-12 P-13 P-14 P-15 P-16 P-17 P-18 P-19 P-20 P-21 Surface Elevation 9i. 2 94.8 94.1 93.5 94. 7 10S. 8 10S.4 106.7 107.6 105.9 107.2 -3- Soil At Test Depth February 13, 1978 Rate Lmp ij- Silty Clay (CL) Silty Clayey Sand, (SM-SC) Silty Clayey Sand, (SM-SC) Silty Cl.,y (CL) Silty Clayey Sand, (SM-SC) Sandy Clay (CL) Sandy Clay (CL) Sandy Clay (CL) Sandy Clay (CL) Sandy Clay (CL) Sandy Clay (CL) *No drop in water level observed. 60 120 240 120 * 480 * * * 480 As shown above, only three of the 21 percolation tests conducted on the lot met the specified minimum standard required for a drainfield system. As noted, some of the areas indicated passing results while no water movement was observed in other areas. This variability in the test results can probably be attributed to one or two factors. Soils in the test holes, particularly in the lower areas, appear to range from silty clays to silty clayey sand which would influence the percolation rate. The more cohesive sandy clays and silty clays would typically have higher percolation readings. The failing rates may also be affected by frost action. Although frost depth throughout the site appears to be somewhere between 1 and 2 feet below the surface, temperature measurements on another lot in Orono conducted February'll indicated that the soil temperature at the 36-inch depth was 320 F. If the water does not freeze when entering the soil, it would be considerably more viscuous, which would limit its flow through the soil pores. PRELIMINARY RECOMMENDATIONS: In a recent telephone conversation with Mr. Mike Gaffron, Septic System Inspector from the City of Orono, we have indicated that a potential drainfield system can likely be established on the lot in the area immediately to the west of the house, based on percolation tests NP-2, P-8, P-10, and P-12. The City has asked that we make a preliminary BRAUR'" ENGINEERING TESTING