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' Report-Pilot Remedial System Test Page 19 Former Manna Pro Site Project No 1011 July 31, 2000 ' 6.0 SAMPLE ANALYTICAL RESULTS 6.1 Soil Sample Analytical Results The soil analytical results are summarized in Summary Table 1 In general, elevated concentrations of gasoline range petroleum hydrocarbons and BTEX compound are ' present in the vicinity of the pilot test from the approximate levels of first groundwater (about 25 feet bgs) and extending downward to about 50 feet Below 50 feet the concentrations decrease as evidenced the samples collected from 50 feet in VEW-1 and ' the one colleOcted from 55 feet in sample from ASW-1 The most intense gasoline concentrations appeared to be in samples submitted for analysis from 30, 40, and 45 foot intervals Low to non-detectable levels of petroleum hydrocarbons were reported in samples from shallower intervals, such as 25 and 30 feet below ground surface This included the vadose zone sand (20-25 feet below grade) which produced the greatest air flow into the vapor extraction well during the pilot test Based on prior estimate by Groundwater Technologies, about 30,000 pounds (9,000 gallons) of gasoline are present in the adsorbed phase This estimate will be reviewed for ' the forthcoming Feasibility Study Report, which will include calculations incorporating the more recent data collected during the monitoring well and soil boring installation completed in April 6.2 Special Soil Analytical Results P Y Based on the of the special laboratory analytical analyses, it appears that bacteria are rgenerally abundant in the soil, but there is a general paucity of hydrocarbon degraders except near the groundwater surface This is best illustrated at the 30 foot level in VEW- 1, where the count of hydrocarbon degrades was about 113 of the total bacterial plate count This sample contained 1,200,000 CFU/g total bacteria of which 400,000 CFU/g were hydrocarbon degraders ' The PTS laboratory data also measured a number of geo-technical characteristics which will be important in possible future aquifer modeling The bulk and grain density were measured for several samples as were the effective and "air" permeability The effective permeability exhibits a decreasing trend with depth In the interval of the most intense gasoline contamination, effective permeability is between 0000027 and 0 00068 ' cm/second (2 70 and 608 millidarcy) or a hydraulic conductivity of 0 1 ft/day to 23 1 ft/day Shallow samples in the through and in the vicinity of the contaminated zone exhibited a porosity of roughly 40-45% Air permeability within the shallow subsurface was measured in the soil sample from MWD-11 from the 25 foot interval at 1,802 millidarcies or 155 7 feet per day ' 2937 Veneman Ave, 4 B24 0 Geo-Phase Environmental Inc Phone(209) 569-0293 Modesto, CA 95356 Fax(209)569-0295