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This test method involves driving two open cylinders, one inside the other, into the soil. Very minor soil cracking was observed in the soil surface where the rings were positioned. Annular spaces were presaturated with 12 inches of water the day before testing. The purpose of the outer ring is to promote one-dimensional, vertical flow beneath the inner ring. The volume of water added to the inner ring to maintain the liquid level constant with the starting value, is the measure of water that infiltrates the soil. Water volume infiltrated during 30 minute intervals for four hours is converted to an incremental infiltration velocity expressed in centimeters per hour(cm/hr), cm/sec and min/in, as illustrated in Table 3. The infiltration test was done at the soil surface, which represents the native soil-effluent interface of the wastewater disposal system. As the soil became saturated, infiltration slow by approximately one-half over the duration of the test. This is illustrated on the Infiltration Test Form found in Appendix C. Test results indicate an infiltration rate somewhat comparable to',the observed percolation rates. The double ring infiltration test results are summarized below: TABLE 3 INFIL'TRATIONILTESURESUETS INFILTRATION RATE IN F!GM/HR,CM/sI C,MIN/IN AND APPLICATION RATE IN GALLONS/FTZ/DAY 4.72 cm/lu,0.0090 cmisec,32.3 min/in,0.545 gallons/ft /day Application Rate adapted from California State Water Resources Control Board Guidelines for the Design of Sewage Systems and is based on the Pcre Rate. D. GROUNDWATER INFORMATION NLS§2.1; SSS 1. Groundwater depths and elevations throughout San Joaquin County are illustrated on lapublished by the County Flood Control and Water Conservation District. However, due to the high degree of variability in groundwater elevations in the Tracy area, groundwater lines of equal depth and equal elevation are not drawn for this area. The last map denoting lines of equal elevation for the Tracy area was published in 1992, and show the general groundwater flow to be in a northeasterly direction,toward the San Joaquin River. This is regarded as the generalized groundwater directional flow,primarily based on highly accurate groundwater studies at the Tracy Defense Depot. The referenced on-site domestic well, which is proposed to be taken out of s vce and a new wel drilled for the project, was sounded with the standing water level measur ai three feet below the top of the casing. During the drilling of the 40-inch deep perc test boring, capill ' e ater was encountered. Unfortunately, no well log was found in EHD files for this domestic well, so well construction details and underlying lithology could not be determined. As referenced, the standing groundwater in the backhoe excavation test pit was measured at D feet below ground surface. A sample from the water table was retrieved with the test res is illustrated in Table 5. i 6 1 lting Chesney Consu z