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Ms. Margaret Russell - 2 - _ 22 August 2000 <br /> 3. Based on the results of the recent investigation, the report recommends the following: NFA to <br /> investigate the vertical extent of TPH pollution; two quarters of groundwater monitoring to <br /> determine whether or not an additional investigation is needed to determine the lateral extent of <br /> groundwater pollution; request NFA in accordance with Appendix B if results of groundwater <br /> monitoring for two quarters show the groundwater plume is stable; and all soil be disposed of onsite <br /> as grading material and all purge, development and decontamination water be disposed of onsite. <br /> Two of the information requirements of Appendix B that Karlson Trucking must provide to get an <br /> NFA are: (1) definition of the lateral and vertical extent of pollution in soil and groundwater and <br /> (2) estimates of mass remaining in soil and groundwater. Based on the recent investigation results, <br /> definition of the lateral and vertical extent of pollution in soil and groundwater is still lacking. This <br /> information is needed to estimate the remaining mass. Therefore, Karlson Trucking should submit a <br /> work plan to determine the lateral and vertical extent of pollution in soil and groundwater. <br /> On 22 August, I discussed the above comments with Mr. Stephen Lankford of GPE. Mr. Lankford and I <br /> agreed with the following: (1) The lateral extent of groundwater needs further definition; (2) The vertical <br /> extent of groundwater pollution is sufficiently defined; and (3) The lateral and vertical extent of soil <br /> pollution needs further definition. In response to my request for an additional investigation work plan, <br /> Mr. Lankford recommended that the groundwater sample results from the newly installed monitoring <br /> wells be confirmed with another round of sampling and if the results show an additional investigation is <br /> needed, GPE would submit a work plan. I agreed with Mr. Lankford's recommendation. <br /> Therefore,by 15 September 2000,please submit a response to the above comments and a schedule to <br /> (1) collect another round of groundwater samples (2) submit groundwater sample results, and (3) submit <br /> a work plan for additional investigation, if necessary. <br /> If you have any questions, you may call me at (916) 255-3081 or e-mail at isorenp@rb5s.swrcb.ca.gov. <br /> *Pw ISORENA <br /> Associate Engineer <br /> cc: Ms. Margaret Lagorio, San Joaquin County Public Health Services, Stockton <br /> Mr. Stephen M. Lankford, Geo-Phase Environmental Inc., Modesto <br />