soil exploration/geoptechinical investigation-2004

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GROUND WATER Observations made to detect in-filled water in the borings are noted on the Boring Logs in Appendix.B. Observations were made at the end of drilling. We observed in-filled water in Borings 1 and 2 at respective depths near 5 and 4 feet. The ground water level within an unconfined aquifer is generally a subdued reflection of the ground surface topography. Ground water generally flows downward from upland lands (recharge areas) - to lower-lying lands or water bodies (wetlands, lakes, streams and rivers) that are discharge areas. Levels of ground water and "perched"water at the project site will vary with climatic oscillations (for example drought or excessive precipitation periods, surface water drainage and site topography). CONSTRUCTION CONSIDERATIONS TOPSOIL REMOVAL Before major grading begins, site areas designated for construction must have topsoil and buried topsoil with undecomposed organic matter stripped away. These soils .can potentially shrink by _ decay of undecomposed organic matter over the life of buildings and other structures. Therefore, topsoil and buried topsoil with undecomposed organic matter must be removed from construction areas, especially those designated for structural fill, buildings, other structures, roadways and other pavements (for example driveways and sidewalks). The topsoil and buried topsoil can either be stockpiled for later use as replacement topsoil in designated landscape areas or wasted onsite or exported off-site. Topsoil with undecomposed organic matter can extend 6 to 18 inches deep, typically. It generally contains grass, roots, undecomposed and decaying vegetation and has faint to strong organic odor. Topsoil thickness may vary across the site. This thickness can be deeper, especially in low- lying areas where topsoil has "washed-in." The boring logs provide roughly estimated and generalized topsoil thickness near the exploratory soil borings. To accurately quantify topsoil thickness for topsoil stripping volume evaluation, we recommend using a backhoe or hand-shovel to dig several test pits across the construction area, . The pits will allow topsoil to be easily observed and measured for thickness. SUBSURFACE WATER IMPACT ON CONSTRUCTION As stated in the GROUND WATER section of this report, we observed in-filled water Borings 1 and 2 at respective depths near 5 and 4 feet at the end of drilling. The Federal Housing Administration (FHA) sets construction standards for housing. In accordance with these standards, we recommend the lowest building floor be at least 4 feet above maximum - anticipated ground water level. In accordance with pavement engineering practice, we recommend pavements be at least 4 feet above maximum anticipated ground water level. If ground water flow- lines approach within 4 feet of the lowest building floor or pavement, considerationmust be given Allied Project 04049 5 July 27, 2004