SU0003602 SSNL - Laserfiche WebLink

Home Browse Search

`r' �,/ 1H KLEINFELDER 6. PERCOLATION TESTING The 6-inch diameter percolation holes were drilled with the same equipment as the soil profile boring. A total of fourteen percolation holes (including the profile holes used for percolation tests) were drilled on the subject property. The holes had scored sides and no significant loose material in the bottoms of the holes. The SJCEHD preparation procedure calls for first placing about 2 inches of fine gravel at the bottom of the borehole. The hole is then pre-soaked with a minimum of 12 inches of water at least 24 hours prior to performing the test. All of the holes drilled on October 7, 2003, (P-1, P-2, P-3, and P-4) were prepared before 6 pm. Due to the late afternoon drilling of the percolation tests on October 7, the tests were performed on October 9 to allow for the minimum 24-hour soaking period required by SJCEHD. Percolation tests at locations P-3 and P-4 were started at 10:30 am on October 9, 2003. Due to inspection scheduling conflicts with SJCEHD, some of the percolation tests could not be performed on October 9 and were started at 10:30 am on October 10 (locations P-1 and P-2). Those tests performed on October 10 were again presoaked on October 9. Due to percolation rates not meeting the percolation requirements of SJCEHD, additional soil profile and percolation holes (locations P-1A, P-2A, and P-3A) were drilled before 11 am on October 13, 2003. These tests were started at 11:30 am on October 14, 2003. All of the tests were performed under sunny and warm weather, using clear potable water in accordance with accepted guidelines. Most of the holes were still intact with no significant sloughing or caving noted. An exception was location P-1, where several inches of fine-grained material had sloughed/washed off the sides and settled in the bottom of the percolation test holes after the test hole preparation. The approximate depth of each percolation test below existing site grade is shown on the following table. The holes were dry prior to testing. From a fixed reference point, a marked location on the side of PVC pipe inserted into the hole, the drop in water level is measured in approximately 30-minute intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel (SJCEHD Procedure #2). Under the observation of a representative from the SJCEHD, the last 30-minute reading of the four-hour period is recorded and used to calculate the percolation rate in minutes per inch. The estimated percolation rates are summarized below. A copy of our field percolation test results signed by a representative from SJCEHD is attached. Details of each test can be found on the percolation test sheet. Test Number Depth, feet Percolation Rate minutes/inch P-1 3.5 125 5 42 P-2 3.5 125 7.4 Did Not Percolate P-3 3 125 7.8 50 10.2 62.5 P-4 3.3 25 13.2 42 36600.G01/ST03RIS37 October 16,2003 ©2003 Kleinfelder,Inc. Page 3 of 7