|
San Joaquin County DIRECTOR
<br /> Donna Heran,REHS
<br /> Environmental Health Department
<br /> ,o.. �..co p AsslsrANT DIRECTOR
<br /> 600 East Main Street Laurie Cotulla,REHS
<br /> Stockton, California 95202-3029
<br /> 5 . PROGRAM COORDINATORS
<br /> Carl Borgman,REHS
<br /> Mike Huggins, REHS,RDI
<br /> cQ�rFo: `�:p Website: www.sjgay.orglehd Margaret Lagorio,REHS
<br /> Phone: (209) 468-3420 Robert McClelton, REHS
<br /> Fax: (209)464-0138 .teff Carruesco,REHS, RDI
<br /> Kasey Foley,REHS
<br /> March 26, 2008
<br /> Stephanie Furgal
<br /> Chevron Environmental Management Company
<br /> 6001 Bollinger Canyon Road Room K2240
<br /> San Ramon, CA 94583
<br /> Subject: Former Unocal #2859
<br /> 1665 Pacific Avenue
<br /> Stockton, CA
<br /> The San Joaquin County Environmental Health Department (EHD) has reviewed the "Fourth
<br /> Quarter 2007 Monitoring and Sampling Report" (Report) dated February 11, 2008, prepared by
<br /> ARCADIS for the above subject site as well as the EHD file for the site and provides the
<br /> following comments.
<br /> The only recommendation in the Report is to modify the groundwater monitoring and sampling
<br /> program. The recommendation is to monitor groundwater levels in all the wells semi-annually,
<br /> collect groundwater samples from MW2, MW3, MW4, MW9, MW10, MW11, MW12, MW15,
<br /> MW16, MW17, MW18, MW20 and NP1 semi-annually and analyze them for TPH-GRO and
<br /> BTEX and add the analysis for 1,2- DCA on the samples from MW4, MW 17, MW18 and MW 19
<br /> annually. The EHD does not approve of this proposal and provides the following directives.
<br /> All the groundwater monitoring wells shall have groundwater levels monitored and samples
<br /> collected and analyzed for TPH-GRO and BTEX at least once per year. Quarterly groundwater
<br /> levels shall be monitored and samples collected from monitoring wells MW2, MW4, MW5,
<br /> MW10, MW11 and MW17 and shall be analyzed for TPH-GRO and BTEX. Semi-annual
<br /> monitoring of groundwater levels and sampling of monitoring wells MW3, MW9, MW12, MW15,
<br /> MW16, MW18, MW19 and NPI with analysis for TPH-GRO and BTEX is acceptable. Analysis
<br /> for 1,2-DCA shall be performed on all groundwater samples collected from monitoring wells
<br /> MW3, MW4, MW5, MW10, MW11, MW17 and MW 19.
<br /> Monitoring well NP1 was originally constructed with a screen interval from 85 to 90 feet below
<br /> surface grade (bsg). Field data sheets in the quarterly monitoring reports after October 2006
<br /> show the total depth of NP1 is about 52 feet bsg. The total depth of NPI must be verified. If
<br /> this monitoring well has been damaged it must be destroyed and replaced. Provide the EHD
<br /> with the status of this monitoring well by May 1, 2008. `
<br /> In a letter (copy enclosed) dated March 21, 2007, to Chevron the EHD commented that the
<br /> recommendations in the fourth quarter 2006 groundwater monitoring report were the same as r
<br /> previous recommendations. Specifically, that the ozone sparge system previously operated at
<br />
|