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two IL SUBSURFACE SOIL CHARACTERISTICS From percolation testing conducted lastear, it was determined the soil oil m the areas of the leachfields and seepage pits may not be conducive to allow sufficient pert rates to dispose of effluent fast enough. The system is functioning properly,however, based upon the operation of the leachfields, seepage pits and the effluent subsurface irrigation. On June 28, two - five foot diameter seepage pits were drilled in the location of the leachf eld which will be servicing the Bingo Parlor. From the volume of soil excavated during this procedure, soil classification and characteristics were easily identifiable. The predominate soil structure for the 25 foot depth consists of a heavy silty clay-clayey silt. This type of'soil structure was relatively consistent and homogeneous throughout the profile depth to 25 feet, except for the stratum from 14 feet to 16 feet, which consists of a fine silty sand structure. The Log of Boring for the east pit is attached to this report. Hydrometer tests were performed on samples retrieved from the 3, 8, 18 and 25 foot depths. These tests were performed according to the American Society for Testing and Materials (ASTM) D-422 - Standard Test Method for Particle-Size Analysis of Soils. Each denoted depth consists of 29%, 21%, 31%, and 34% clay contents, respectively, for an average clay percentage of 26%. These percentages can be considered a high clay content soil. Permeability tests were performed on samples obtained from the fine sand strata and the remaining clay strata according to CALTRANS Test 220 - Method of Test For Permeability of f Soils. Due to the relative homogeneity of the clay content throughout the soil profile, samples L were used from the above-referenced depths. The fine sand strata exhibited a slower than expected permeability of 10-4 cm/sec. The clay fraction test results indicated a permeability of approximately 10' cm/sec. Both of these measurements represent comparatively slow permeabilities. The subsurface clay fraction is favorable for the prevention of contamination of the groundwater from pathogens such as bacteria and viruses. This is primarily due to bacterial retention in these finer-textured soils in which physical filtration is predominate. Additionally, adsorption of microbes onto clay particles is another important factor. Potential contamination from pathogens 2 Vafley V Ppearch