Laserfiche WebLink
September 3, 2004 <br /> NOA Project Number: E04025A <br /> Page 4 <br /> Table 1. <br /> Summary of Percolation Test. <br /> Test Time Period of Test,Date Percolation Rate <br /> Boring near 10 ft level <br /> P-1 4 hour test,July 1, 2004 7.4 min/in or 16.3 ft/day <br /> P-2 4 hour,July 1,2004 0.4 min/in or 296 May <br /> P-3 3.5 hour,July 13, 2004 2.0 min/in or 60 May <br /> Calculating Flow Rates From Percolation Tests <br /> The percolation rate in feet per day was used to determine the expected flow rate for a 5-foot <br /> diameter seepage pit. Based on the following calculations, the average CWR per percolation test <br /> was found to be 2,924 gal/day. <br /> The following calculations indicate the steps and numbers used for the conversion from <br /> percolation rate to flow rate which accounts for test hole size and gravel porosity. A table of <br /> possible sewage reduction factors is also presented. Even though clear water rates may be <br /> relative high, a sewage reduction factor should be applied to the CAR to account for can reduce <br /> the infiltration rate over time. The calculations are as follows: <br /> Porosity was measured at 40%for gravel, test boring radius is 0.5 feet, 1 ft' = 7.48 gallons <br /> Clear water rate (ftp/day)=percolation rate (ft/day)x (test hole radius x pi)ftp x porosity <br /> For P-1 (I foot diameter hole) <br /> CWR = 16.3 ft/day x (0.5 2 x 3.14)ftp x 0.40 <br /> CWR = 5.15 ft3/day <br /> CWR = 41 gal/day <br /> Adjust flow rate for a 5 foot diameter hole <br /> CWR = (5 ft x 41 gal/day)/0.5 ft <br /> CWR = 410 gpd <br /> For P-2 (I foot diameter hole) <br /> CWR = 296 ft/day x (0.51 x 3.14)ft1 x 0.40 <br /> CWR = 92 ft lday <br /> CWR = 695 gal/day <br /> Adjust flow rate for a 5 foot diameter hole <br /> CWR = (5 ft x 695 gal/day)/0.5 ft <br /> CWR = 6,952 gpd <br />