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r <br /> r February 6, 2006 <br /> NOA Project Number. E05173A <br /> 6.2 Number of Percolation Tests <br /> r <br /> One shallow ercolation test was conducted o each arcel of the Site for a total six shallow <br /> per�o tests. Two test borings and percola ests were redrilled and repea at the same <br /> locations. <br /> 6.3 Boring Preparation and Presaturation j <br /> NATS Laboratories, Modesto, drilled the soil borings by two man gas powered augur drill with 6- <br /> inch auger. Gravel was placed in the bottom of the hole and a 4-inch diameter perforated PVC pipe <br /> r was placed in the open hole to observe the water drop. <br /> Presaturation of the percolation test holes occurred 24-hours prior to the tests according to NATS <br /> Laboratories,Modesto. <br /> i <br /> 6.4 Condition of Borings After Presaturation <br /> After the 24-hour soak period, the presaturated holes were found to be intact and dry on the day of <br /> testing by NATS Laboratories,Modesto. <br /> r <br /> 6.5 Percolation Test Procedure <br /> The percolation tests were conducted on November 18 and 22,2005 and January 20, 2006 in <br /> accordance with the requirements of the EHD. A percolation test with a duration of four hours was <br /> performed for each hole. The final half-hour of the four-hour percolation tests were observed by a <br /> Registered Environmental Health Specialist of San Joaquin County. The tests were conducted by <br /> NATS Laboratories. <br /> Measurement of the water level during the percolation test was from a fixed reference point on the <br /> PVC casing using an electric well sounder with an depth accuracy of 1/AAQth foot. All tabulated <br /> values on the field data sheet (appendix) are in decimal feet. After water drop was observed, the <br /> holes were checked for refill. The refill level was approximately 0.5 C76-inches of water above the <br /> bottom level of the percolation test hole. The readings were taken approximately every 30 minutes <br /> for a period of four hours. <br /> 6.6 Percolation Test Forms and Results <br /> The completed percolation test forms are included in the appendix of this report. <br /> A shallow percolation test is defined by the EHD as being between 36 and 42 inches in depth;a <br /> satisfactory percolation rate for a shallow test is less-than or equal to 60 minutes per inch drop. <br /> Details of the percolation tests are summarized' Table 6. <br /> 8 <br /> V <br /> rr <br />