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June 16, 2004 NOA Project Number: E04069A 6.2 Boring Preparation and Specifications The shallow boring was advanced by hand auguring to 3.21 feet on June 8, 2004. A 2-inch diameter PVC pipe with perforations on the bottom was used to measure the drop of water in the percolation test boring. Approximately 2 inches of"pea gravel" were placed in the bottom of the boring, then the PVC pipe was installed on top of the gravel. Several feet of"pea gravel" were backfilled in the annular space. 6.3 Presaturation of Borings Presaturation of the percolation test holes occurred on June 8, 2004. The depth of water used to presoak was 12 inches above the bottom of the borings. After the 24-hour soak period, the presaturated holes were found to be intact and dry on June 9, 2004. 6.4 Percolation Test Procedure and Results One 1-hour percolation test was conducted on June 9, 2004 in accordance with the requirements of the San Joaquin County EHD. The pretest and the entire 1-hour percolation test was observed by Ms. Lisa Medina, Registered Environmental Health Inspector, EHD. Measurement of the water level during the percolation test was from a fixed reference point on the PVC casing using an electric well sounder with an depth accuracy of 1/100th foot. All values on the field data sheet (appendix) are in decimal feet unless otherwise noted. After water drop was observed, the holes were checked for refill. The refill level is 6 inches of water above the bottom level of the percolation test hole. The readings were taken approximately every 10-minutes for the 1-hour duration test. A satisfactory percolation rate for a shallow (3-3.5 foot deep) test is 60 min/in or less. The shallow percolation test passed with a percolation rate of less than 1.4 min/in. Details of the percolation test are presented in Table 4. 7 -*44