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r SAN JOAQUIN COUNTY PUBLIC HEAVTH SERVICES <br /> ENVIRONMENTAL HEALTH DIVISION <br /> UGST SITE MITIGATION UNIT- GENERAL RISK APPRAISAL <br /> Explanation of the General Risk Appraisal: <br /> ite Address 8m) <br /> The general risk appraisal was developed using <br /> ite code 11C)49 Facility Name environmental fate and chemistry data for BTX&E <br /> to evaluate the risk of groundwater pollution <br /> from LUFT sites under severe conditions. This <br /> risk appraisal requires a Limited amount of site- <br /> . Is the site in a mountainous area? (Shaded NO YES specific information; conservative assumptions <br /> moist areas and/or areas with rocky subsurface have been substituted for other site-specific <br /> conditions) information. For these reasons, the general risk <br /> appraisal is more sophisticated than the Leaching <br /> 2. Is the site in an area that could cotlect surface Potential Analysis. <br /> runoff or intercept water from a source other than <br /> the natural precipitation? <br /> 3. Does the areal extent of soil contamination exceed <br /> 1000 ft2? <br /> Do the concentrations of fuel constituents in any <br /> soil samples exceed the following amounts? <br /> [benzene: 100 ppm; toluene: 80 ppm; xylene: 40 ppm; <br /> ethylbenzene: 40 ppm] <br /> 5. Are there any records or evidence of man-made or <br /> natural objects which could provide a conduit for <br /> vertical migration of leachate? [septic systems; <br /> leaching fields; wells; soil borings] <br /> . Do any boring or excavation togs show the presence / <br /> of fractures, joints or faults that could act as a ✓ <br /> conduit for vertical migration of leachate? <br /> . Do any boring logs show that contaminated soil could <br /> be within 5 feet of highest ground water? <br /> 5. Do any boring logs show the presence of a layer of / <br /> material, 5 feet thick or more, which is more than <br /> 75% sand and/or gravel (coarse soil)? <br /> Directions: <br /> 1. Boring togs drilling at the site can be used to answer questions <br /> 5 - B. Analytical results of the soil samples collected during the <br /> borings can be used to answer questions 3 and 4. <br /> 2. Lateral migration of constituents to problem areas should also be <br /> considered in questions 5-8. <br /> NOTE: The above checklist contains questions which are designed to identify <br /> sites with environmental conditions which could produce a greater risk <br /> to groundwater than was modeled through the usage of the Leaching Potential <br /> Analysis. The results of the general risk appraisal are most applicable <br /> if all the questions on the checklist can be answered "no" with reasonable <br /> certainty. If any of the questions on the checklist cannot be answered <br /> "no", then the results of the genera[ risk appraisal may be less valid. <br /> If answers to the checklist questions irx[icate that the general risk <br /> appraisal results are not valid enough to be practical, then the LUFT <br /> Environmental Fate Worksheet should be considered. <br /> EH UNIT VI 2/91 RISKASMT <br />