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4fA-N--� CONSTRUCTION iql"14� TESTING SERVICES Infiltration rates were calculated from the percolation data according to the Porchet Method. It should be noted that the percolation rate is related to, but not equal to,the infiltration rate. While an infiltration rate is a measure of the speed at which water progresses downward into the soil,the percolation rate measures not only the downward progression but the lateral progression through the soil as well.This reflects the fact that the surface area for infiltration testing would include only the horizontal surface while the percolation test includes both the bottom surface area and the sidewalls of the test hole. The Porchet Method is a relationship used to convert the values obtained by a percolation test to an approximate infiltration rate. The results of the tests are presented in the table below. The rates shown below were calculated from averaging the last 3 percolation and infiltration rates calculated at each test location. DepthPercolation and Inflltration Rates III Bedding • Percolation Rate InfiltrationRate PT-1 52.0 48.0 50.0 0.06 PT-2 51.5 46.5 36.9 0.071 PT-3 50.5 47.0 40.0 0.03 PT-4 51.0 47.0 16.7 0.20 Subsurface soils are inherently variable both laterally and with depth. As such, an additional factor-of- safety should be included in the final design. If you have any questions regarding the contents of this letter, or if we could provide further assistance, please contact the undersigned. Sincerely, CONSTRUCTION TESTING SERVICES Emanuel Va encia for Mike Turner, CEG Staff Engineer Associate Geo t Bradford Quon, GE Vice President of Geotechnical Engineering Attachments: Plate 1 Vicinity Map Plate 2 Test Locations SJCEHD Approved Test Results 400 Yankee Hill Road,Rocklin,CA 95677•Phone(916)419-4747•Fax(916)419-4774 2118 Rheem Drive,Pleasanton,CA 94588•Phone(925)462-5151•Fax(925)462-5183