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Laurie Cotulla July 31, 1990 g Page 2 # ; 4 photoionization detector (PID). Three additional trenches ally contained gasoline odor at different depths below the surface, including one trenchiexcadated in a direction believed to be downgradient from the former tank location. Although this trench contained only a mild odor in the soil within the walls of the excavation, a sheen was still easily seen on ;p the surface of the water. SOIL BORINGS Augeas Corporation proposes to drill four soil borings at the locations shown in Figure 1. The borings will be drilled and continuosly cored using a truck-mounted hollow-stem auger drill rig. Detailed lithologic logs will be kept on each boring and soil samples collected at five-foot intervals. Each soil sample will be screened in the field using a portable PID capable of detecting benzene. Only those samples registering detectable levels of total petroleum hydrocarbon products will be saved for subsequent chemical analysis. Soil samples will be collected using a standard California sampler containing three 6-inch brass liners. The middle of the three liners will be sealed with'.plastic end-caps and wrapped in duct tape, labeled on a Chain of Custody form and placed in an ice chest cilled to approximately 4 degrees until transported to California Water Labs, a Certified analytical laboratory located in Modesto. In addition to collecting soil samples at five foot intervals, Augeas personnel will also collect a soil sample at the soil/water interface in each boring. Total depth of the soil borings is anticipated to be 13 feet. GROUNDWATER CONTAMINATION ASSESSMENT . Because of the shallow nature of the water table, it appears t at minor contamination of the upper groundwater aquifer beneath the site has occurred as a result of seepage of gasoline from the product line leading from the former above-ground tank. Augeas Corporation proposes to install three groundwater monitoring wells in the locations shown on Figure 1 to determine the amount of contamination present and to verify the rate and direction of groundwater flow. Detail lithologic logs will'1 be kept on each boring and soil samples will be collected by driven sampler at 5 foot intervals) as described above. i Well Installation '� If Augeas Corporation proposes to install all three groundwater monitoring wells down to a depth of 25 feet using a 10-inch diameter hollow-stem augerp drilling rig. The wells will be constructed with 15-feet of factory slotted well screen?located at the 8 to 23-foot depth interval. This will result in the screened intervals being;placeid so that 10 feet of screen will be below and 5 feet of screen will be above the water table. All three wells will use k �i I� Y