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SIGNET STL Project No. 0010771 —� TL-sdng Labs Page 5 GROUNDWATER Test boring locations were checked for the presence of groundwater during and immediately following the drilling operations. Free groundwater was not encountered. It should be recognized that water table elevations might fluctuate with time, being dependent upon seasonal precipitation, irrigation, land use, and climatic conditions as well as other factors. Therefore, water level observations at the time of the field investigation may vary from those encountered during the construction phase of the project. The evaluation of such factors is beyond the scope of this report. PERCOLATION TESTING Two percolation tests were performed in the location of the proposed retention basin at the . _ est Qortion of the site. The percolation borings were drilled to a maximum depth of six feet below existing _ site grade, the elevation of the proposed basin bottom. After drilling, 3%cinch diameter plastic perforated pipes were placed in the test holes and the annularsnaces were filled with #30 sand. The test holes were presoaked for a minimum of 24 hours and then re-hydrated. The results of our test ` determinations are presented for your consideration: �— SUMMARY OF PERCOLATION TEST RESULTS Location Soil Description Depth percolation Rate South End Fine Sandy Silt (ML) 5 feet 37 min./inch North End Fine Sandy Silt (ML) 6 feet17 min./inch CONCLUSIONS AND RECOMMENDATIONS Based on the findings of our field and laboratory investigations, along with previous geotechnical experience in the project area, the following is a summary of our evaluations, conclusions and recommendations. Administrative Summary. In brief, the subject site and soil conditions appear to be conducive to the development of the project. The upper twelve to eighteen inches of soil had fair to moderate strength characteristics but were _ moderately compressible when saturated. The soils encountered below this depth exhibit moderate strength characteristics and were only slightly compressible. Therefore, it is recommended that the upper 18 inches of soil within the proposed building pads and paved areas be scarified, properly moisture conditioned, and compacted to a minimum of 90 percent of the maximum laboratory dry density as determined by ASTM Test Method D1557. "' 1417 No. Market Blvd.,Suite 1 • Sacramento,CA 95834 • (916)568-5858 • Fax: (916)568-5813