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San Joaquin County <br /> Environmental Health Department DIRECTOR <br /> Linda Turkatte, RENS <br /> 1868 East Hazelton Avenue <br /> Stockton, California 95205-6232 PROGRAM COORDINATORS <br /> Robert McClellon,REHS <br /> •' - - Jeff Carruesco, REHS, RDI <br /> cd ti�P Website: www.sjgov.org/ehd Kasey Foley,REHS <br /> `f FOR Phone: - Rodney Estrada, REHS <br /> 209 <br /> ( ) 4683420 Adrienne Ellsaesser,REHS <br /> Fax: (209) 464-0138 <br /> March 12, 2015 <br /> Carl Knowles <br /> PO Box 640 <br /> Woodbridge, CA 95258 <br /> Subject: Request for Closure - Response Site Code: 1124 <br /> 1140 West Hammer Lane (a.k.a. 7835 Thornton Rd.) <br /> Stockton, CA 95209 <br /> The San Joaquin County Environmental Health Department (EHD) has reviewed Fourth Quarter <br /> 2014 Groundwater Monitoring and Remediation Status Report and Request for Environmental <br /> Case Closure Review (GWMR) dated January 28, 2015, prepared and submitted by Stratus <br /> Environmental, Inc. (Stratus). GWMR contains a request for case closure review for <br /> conformance to criteria presented in the Low-Threat Underground Storage Tank Case Closure <br /> Policy. <br /> On September 10, 2012, ozone injection (OI) remediation was initiated at the subject site <br /> utilizing injection wells (IW) to inject an air/ozone mixture into the subsurface to remediate the <br /> fuel contamination in groundwater at the site. According to data presented in GWMR, OI <br /> appears to have significantly reduced fuel contaminant concentrations in groundwater at <br /> monitoring well MW-11, screened 30 to 50 feet below surface grade (bsg). However, fuel <br /> contaminant concentrations in groundwater at MW-12, screened 48 to 58 feet bsg, appear to be <br /> unaffected. Given that IW-4A/B contains gas diffusers in roughly the same interval as MW-12's <br /> screened interval and is the closest IW to MW-12, the EHD recommends focusing additional <br /> ozone injection in IW-4A/B for two quarters and evaluate the response; if favorable, the EHD will <br /> consider rebound monitoring, following cessation of Ol, to evaluate for case closure. <br /> At this time, the EHD does not concur with the request for case closure as dissolved benzene <br /> concentrations in MW-12 still exceed 1,000 micrograms per liter (pg/1) and show no response to <br /> the OI so far. This decision is subject to appeal to the State Water Resources Control Board <br /> (State Water Board), pursuant to H&SC Section 25296.40 (a) (1), (Thompson-Richter <br /> Underground Storage Tank Reform Act - Senate Bill 562). Please contact the State Water <br /> Board Underground Storage Tank Program at (916) 341-5752 or visit the State Water Board <br /> internet website at: http://www.waterboards.ca.gov/ust/cleanup/petitions.html for information <br /> regarding the appeals process. <br /> On March 11, 2015, an EHD representative visited the site during a groundwater sampling <br /> event. The IWs' well boxes were observed without well lids and contained stagnant water and <br /> debris. Wells shall be fitted with a watertight seal to prevent surface water, pollutants, and <br /> contaminants from entering the well. Install seals/lids which will meet this requirement. In <br /> addition, detectable gaseous odor, noise and bubbling of stagnant water in the well box of IW-1 <br /> ;-,4i--+o,4 � pow n+ nnA of thin knrall ca-,inns A Stratus representative onsite managed to reduce <br />