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LEEDS14ILL HERKENHOFF INC <br /> REGULATORY GUIDELINES <br /> 5.1 EVALUATION OF SOIL <br /> In 1985, the Department of Health Services (DOHS) and the State Water Resources <br /> Board ,jointly published the Leaking Underground Fuel Tank (LUFT) Field Manual <br /> as a guidance manual to aid representatives of the state and local agencies and <br /> consultants in conducting underground tank investigations and the evaluation of <br /> hazards created by unauthorized releases of gasoline and diesel products <br /> One section of the LUFT Manual provides guidance in establishing site-specific <br /> soil clean-up levels for BTX&E and TPM. The manual suggests the investigator <br /> use two analyses for determining appropriate clean-up levels, first a leaching <br /> potential analysis and second, a general risk appraisal . The leaching potential <br /> analysis will result in maximum allowable residual soil levels of BTX&E and TPH, <br /> which are to be compared to analytical results obtained for each discrete sample. <br /> The general risk appraisal is then used to determine whether the BTX&E residuals <br /> left in the soil will pose a continuing threat to groundwater resources. <br /> The leaching potential analysis looks at five site specific characteristics which <br /> tend to greatly influence vertical contaminant migration; (1) groundwater depth, <br /> (2) average annual precipitation, (3) subsurface fractures, (4) man-made conduits <br /> and (5) unique site features. Each of the aforementioned characteristics are <br /> evaluated using a numerical scoring system from 0 to 10, with a score of 10 <br /> indicating low potential for leaching The LUFT Manual sets guidelines for <br /> scoring each characteristic. The sum of each of the individual scores is then <br /> used to set maximum allowable residual BTX&E and TPH levels that can be left in <br /> place without posing a threat to groundwater. <br /> Using the recommended LUFT procedure, the following table lists the site feature, <br /> the score and the sum for 102 South Wilson lay: <br /> Site Feature Score 1/ <br /> ' 1. Minimum Distance to groundwater from soil 5 <br /> sample (greater than 25 feet but less than 50) <br /> 2. Fractures in subsurface (none) 10 <br /> (applies to foothills and mountain areas) <br /> 3 Average Annual Precipitation (13.8") 9 <br /> 4. Man-made Conduits (none) 10 <br /> 5. Unique site features (none) 10 <br /> (includes recharge area, nearby wells, coarse <br /> soil , etc.) <br /> 44 <br /> 1/ Score approximated by LH following LUFT recommendations <br /> -23- <br />