|
California Tank Lines, Inc.
<br /> Page 2 of 2
<br /> By telephone on October 3, 2006, EHD recommended to EI that the proposed Geoprobe or "push
<br />;I drill" soil borings be replaced with cone penetromer test (CPT) borings. This would provide
<br /> continuous logs of computer-interpreted soil types and identify locations for collecting depth-
<br /> discrete grab groundwater samples. EHD also directed that at least three soil borings instead of
<br /> one boring be advanced on the east side of El Dorado Street to better detect hydrocarbon
<br /> contamination in this direction.
<br /> Although EHD's letter dated May 22, 2006, specifically noted the contamination associated with
<br /> MW-4, there is also a need to investigate your site at and beyond the areas of MW-1 and MW-2.
<br /> The vertical and lateral extent of all COCs must be delineated in soil and groundwater.
<br /> Specifically, hydrocarbon contamination in groundwater has not been delineated vertically in the
<br /> source areas, and laterally north and northwest of MW-2, and west of 11AW-1 ; and hydrocarbon
<br /> contamination in soil has not been vertically delineated near MW-2 . Grab groundwater samples
<br /> collected from borings B-3 and B-4 with total depths of 50 feet bgs indicate the presence of high
<br /> concentrations of methyl tertiary butyl ether (MTBE) in addition to other COC and soil samples
<br /> collected at thirty feet bgs at MW-2 and B-3 indicate the presence of high concentrations of total
<br /> petroleum hydrocarbons as gasoline (TPH-g). Please amend the work plan to include
<br /> investigating the vertical extent of petroleum hydrocarbon contamination in groundwater at the
<br /> locations of the former underground storage tanks (USTs), in soil near MW-2, and in
<br /> groundwater laterally to the north, northwest, and west of the former USTs.
<br /> Di-isopropyl ether (DIPE), tertiary-butyl alcohol (TBA), 1 ,2-dichloroethane (1 ,2-DCA), and 1 ,2-
<br />? dibromoethane (EDB) have historically been detected in groundwater samples collected at MW.
<br /> 4. Therefore, EHD directs that DIPE, TBA, 1 ,2-DCA, EDB, ethyl tertiary butyl ether (ETBE),
<br /> and tertiary-amyl methyl ether (TAME) be included in all soil and groundwater analyses in
<br /> addition to the proposed analyses for TPH-g, total extractable petroleum hydrocarbons as diesel
<br /> (TEPH-d), TEPH as motor oil (TEPH-mo), benzene, toluene, ethylbenzene, and total xylenes
<br /> (BTEX), and MTBE. Please report 1 ,2-DCA and EDB at 0.5 micrograms per liter (4g/L) in
<br /> ji groundwater samples, if possible, and report detected results for MTBE by Environmental
<br /> Protection Agency SW-846 Method 8260B.
<br />;I
<br /> Please submit an addendum to this work plan that will address the items noted in this letter to
<br /> EHD by November 30, 2006. Include cross sections, boring logs; tables containing soil and
<br /> groundwater analytical results from previous and current borings, and a rose diagram when
<br /> submitting the report of findings following this investigation.
<br /> Should you have any questions or concerns regarding this letter, please contact Vicki McCartney
<br /> at (209) 468-3456, or by e-mail at vmccartney@sjcehd.com.
<br /> Donna Heran, REHS, Director
<br /> Environmental Health Department
<br /> Victoria L. McCartney, Semor REHS Nuel C. Henderson, Jr., PG
<br /> Unit IV-Site Mitigation Unit IV- Site Mitigation
<br /> c : James L.L. Barton, PG — CVRWQCB
<br /> Guy Roy — EI
<br /> i
<br />
|