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CalifornVegional Water Quality Cor of Board
<br /> Central Valley Region
<br /> Karl E. Longley,Sc D, P.E..Chair
<br /> Linda S.Adams Arnold
<br /> �., „r rl� Sacramento Hain Office
<br /> 11020 Sun Center I)me 0200.Rancho Cordova.California 9�6(1 61 14 SchN%a rzenegger
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<br /> Prr,lechun Phone(9 16 464-3291 •FAX(9 16)464-464> D1�r�—
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<br /> 12 October 2007 OCT
<br /> Mr. Matt Gabris 1�lipU�J/t�
<br /> Sara Lee Bakery Group, Inc P `Y.f.
<br /> 3500 Lacey Rd.
<br /> Downers Grove, IL 60515
<br /> DOCUMENT REVIEW, FORMER COLUMBO/TOSCANA BAKERIES, 1444 S. LINCOLN STREET,
<br /> STOCKTON, SAN JOAQUIN COUNTY (WATER BOARD CASE # 390825)
<br /> I reviewed the 9 October 2007 Soil and Groundwater Investigation Report (SGIR) and the
<br /> 10 October 2007 Quarterly Groundwater Monitoring Report (Third Quarter— July 2007) or
<br /> (3Q2007MR), submitted by your representative Phillip Environmental Services Corporation (PSC) and
<br /> your consultant ETIC Engineering (ETIC).
<br /> The SGIR provides the results of soil and grab groundwater sampling from 11 direct push borings
<br /> (Cl through C11) advanced in May 2007, and the subsequent installation of 4 groundwater monitoring
<br /> wells (MW-1A through MW-4A) in July 2007 (enclosed Figure 7). Depth to groundwater varied from
<br /> 18 to 20.5 feet below ground surface. Maximum soil boring concentrations were Total Petroleum
<br /> Hydrocarbons as gasoline (TPHg), 3,400 milligrams per kilogram (mg/kg); benzene, 38 mg/kg; toluene,
<br /> 200 mg/kg; ethylbenzene. 120 mg/kg; xylenes. 700 mg/kg; methyl tert-butyl ether (MtBE), 1.2 mg/kg;
<br /> tertiary butyl alcohol (TBA), 0.15 mg/kg; and 1,2-dichloroethane (1,2-DCA), 0.048 mg/kg. Maximum
<br /> grab groundwater concentrations were TPHg, 400,000 micrograms per Liter (ug/L); benzene,
<br /> 26,000 ug/L; toluene, 51,000 ug/L; ethylbenzene, 7,800 ug/L; xylenes, 38.000 ug/L; MtBE, 1,700 ug/L;
<br /> TBA, 400 ug/L; di-isopropyl ether (DIPE), 1.4 ug/L; ethyl tertiary butyl ether (ETBE), 1.0 ug/L; and
<br /> 1,2-DCA, 230 ug/L. The SGIR states the majority of the soil contamination and groundwater pollution
<br /> reside within a source area centered beneath and adjacent to the former USTs; that the extent of the
<br /> release has not been fully characterized by the current investigation; and recommends submitting a
<br /> Site Conceptual Model (SCM) to show data gaps in the current investigation and potential interaction
<br /> from neighboring sites' (enclosed Figure 2) groundwater pollution, prior to proposing future
<br /> investigations.
<br /> The 3Q2007MR states that liquid-phase hydrocarbons (free product) have been effectively remediated
<br /> onsite by bailer or absorbent sock, and free product is no longer detected in monitoring well VE-1. The
<br /> maximum petroleum hydrocarbons concentrations in groundwater monitoring well samples were TPHg,
<br /> 120,000 ug/L; 19,000 ug/L; toluene, 24,000 ug/L; ethylbenzene, 3,400 ug/L; xylenes, 20,000 ug/L;
<br /> MtBE, 3,000 ug/L; TBA, 130 ug/L, and 1,2-DCA, 3.1 ug/L. The QMR recommends changing the
<br /> monthly sampling schedule for VE-1 to quarterly monitoring.
<br /> Comments:
<br /> 1. 1 concur with the 3Q2007MR recommendation to resume quarterly groundwater monitoring for
<br /> VE-1, and to immediately resume free product removal upon its detection in future monitoring
<br /> events.
<br /> 2. 1 concur that an SCM may be helpful to determine the distribution of potential additional sources
<br /> of the pollution; however, two SCMs (508 W. Charter Way submitted in April 2004. and
<br /> California Environmental Protection Aaenc),
<br /> Z�e� Herr(led 1'rpri
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