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PUBLIC `-HEALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> ENVIRONMENTAL HEALTH DIVISION ` <br /> Ernest M. Fujimoto, M.D., M.P.H., Acting Health Officer c�•.. a <br /> 445 N. San Joaquin Street • P.O. Box 388 • Stockton, CA 95201-0388 <br /> (209) 468-3420 <br /> ERNEST COSTAMAGNA COPY <br /> E G C INVESTMENTS, INC. <br /> P 0 BOX 262 JAN Q 9 i995 <br /> BANTA CA 95304 <br /> RE: Farm Tank Investigation SITE CODE: PR#004367 <br /> 18775 Tom Paine Rd <br /> Tracy, Ca 95736 <br /> Thank you for submitting the required items requested from San Joaquin County Public Health Services, <br /> Environmental Health Division (PHS-EHD). Enclosed please find the copies of the completed forms you <br /> requested. <br /> After review of previously submitted reports by another consultant and discussions with staff, PHS-EHD has <br /> concluded that the lateral limits for soil contamination has been defined for all quadrants. <br /> Groundwater collected approximately 50' north, 40' west, and 90' south of the old tank pit showed low levels of <br /> TPH-G and BTEX. Previous attempts to gather a groundater sample from the eastern quadrant were unsucessful. <br /> Due to the existence of unacceptable residual petroleum still in place and the unknown easterly area, further <br /> groundwater investigation will be required. <br /> PHS-EHD realizes the five trenches proposed in this workplan reflect the original request for full soil and <br /> groundwater lateral definition and hopes you understand that now this proposal does not meet the updated status <br /> of the site. <br /> PHS-EHD feels that sampling at discrete points, rather than trenching, would better aid in screening the lateral <br /> limits of groundwater contamination. <br /> Repeatable and discrete water sampling events are required in order to confirm the absence or presence of <br /> contamination. Sample collection from trenches cannot supply discrete data and as such will not suffice as <br /> evidence to confirm or deny the presence of contamination. In addition, hydraulic gradient cannot be obtained <br /> from trenches unless they were left open. Being open and exposed to cross contamination and the loss of <br /> volatiles, trenching would not provide you with accurate groundwater data. Only proposals that allow for <br /> repeatable water sampling at discrete points will meet minimum requirements for underground storage tank <br /> investigation and be accepted by PHS-EHD. <br /> Item 12 of the workplan identifies EPA Method 8015 modified for the analyses of all of the compounds <br /> Benzene, Toluene, Ethylbenzene, Xylene (BTEX) and Total Petroleum Hydrocarbons as Gasoline (TPH-G). <br /> This one method will not adequately analyze the BTEX constituents. <br /> Please utilize EPA Method 602 (or 502) for BTEX analyses in groundwater with minimum detection limits of <br /> 0.5 ug/l. <br /> PHS-EHD will require EPA Method 8015 modified with purge and trap preparation 5030 (GC/FID) to be <br /> utilized for analysis of TPH-G in water samples. Minimum detections limits shall be 50 ug/l for water samples. <br /> A Division of San•Ioaituin County Health Care Services <br />