SITE INFORMATION AND CORRESPONDENCE_FILE 3

Home Browse Search

All -0 San Joaquin County Evironmental Health Denartment DIRECTOR Environmental p Pp u.iN c M Donna Horan.RENS 1868 East Hazelton Avenue PROGRAM COORDINATORS N Stockton, California 95205-6232 Robert McClellon,REHS Jeff Carruesco,REHS,RDI Kasey Foley,REHS 0 .. Website: www.slgov.org/ehd Linda Turkatte,REHS q� FoR. Phone: (209)468-3420 Rodney Estrada,REHS Fax: (209) 464-0138 Adrienne Ellsaesser,REHS September 20, 2013 Mr. Paul Zumberge and Ms. Daren Zumberge Frontier Transportation, Incorporated 3577 West Philadelphia Chino Hills, California 91710 Subject: Frontier Transportation, Incorporated 425 Larch Road Tracy, California 95376 Dear Mr. Paul and Ms. Daren Zumberge: The San Joaquin County Environmental Health Department (EHD) has received and reviewed Addendum to Proposed Work Plan for Groundwater Remediation (addendum), dated 27 August 2013, prepared and submitted by your consulting firm, EnviroMonitoring Services, Inc. (EMS), on your behalf for the above-referenced site. The work plan addendum was submitted following the EHD request by letter dated 18 July 2013 for additional information concerning EMS's proposal to conduct a water pumping test. In the addendum, EMS presented data collected during the aquifer pump test completed in October 2006 by Biophysics Environmental Assessment, Inc. EMS noted that concentrations of contaminants of concern were highest in soil samples collected at ten feet below surface grade (bsg) compared to five, fifteen and twenty feet bsg; soil hydraulic conductivity increased with depth between five and twenty feet bsg; and during the pump test, maximum drawdown decreased with distance in wells adjacent to and screened within the same interval, five to twenty feet, as pumping well MW-3R; the pump test had no influence on the one deep well, MW-13, screened between thirty and forty feet bsg. Based on information presented in the aquifer pump test, EMS proposes to perform a depth- discrete pump test to assess groundwater flow rate and petroleum hydrocarbon contaminant concentrations in the shallow 'more impacted' groundwater, above thirteen feet bsg, and in the 'less impacted' groundwater in the deeper zone, below thirteen feet bsg. To accomplish this, EMS proposes: Installation of a temporary inflatable packer into each of two proposed pumping wells at approximately thirteen feet bsg to block the flow of water within the well casing during the pump test; Use of dual-phase extraction well DPE3 and monitoring well MW-3R as pumping wells; Performance of the pump test for twenty hours for each zone (shallow and deep) per pumping well;