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, t I • <br /> _ Evmuv0 0.Bnown JR. <br /> y _ owennon <br /> vurro44u MAnxEw ROVPIOVFZ <br /> .,,6.M FOP <br /> Water Boards oPmtxtA,.�.t ne. <br /> Central Valley Regional Water Quality Control Board <br /> 10 September 2015 <br /> Dana Perry <br /> Reynolds and Brown <br /> 1200 Concord Ave, Suite 200 <br /> Concord, CA 94520 <br /> SITE ASSESSMENT WORK PLAN ADDENDUM COMMENTS; FORMER <br /> PILKINGTON NORTH AMERICA INC, 500 EAST LOUISE AVENUE, LATHROP, <br /> SAN JOAQUIN COUNTY <br /> Staff of the Central Valley Regional Water Quality Control Board (Regional Water Board) have <br /> reviewed Site Assessment Work Plan Addendum-June 2015(WP Addendum) submitted on <br /> behalf of the Former Pilkington North America (PNA) by Advanced GeoEnvironmental Inc. for <br /> the investigation and cleanup of the 1996 diesel fuel spill at 500 East Louise Avenue in Lathrop <br /> (Site). The WP Addendum was submitted to address Regional Water Board Site Groundwater <br /> Investigation Work Plan Comments letter, dated 16 March 2015, requesting revision of 6 June <br /> 2014 Site Groundwater Investigation Work Plan (Work Plan)to include staff recommendations. <br /> Regional Water Board staff requested the Work Plan to address the following data gaps: <br /> (a) investigate whether total petroleum hydrocarbons (TPH) have migrated to deeper soil strata, <br /> (b) define down-gradient extent of contamination, (c) determine if site pollution is migrating' <br /> offsite, and (d) develop a plan to restore the quality of groundwater. <br /> The Work Plan proposed: <br /> 1) Groundwater investigation using direct push boring procedures in fourteen locations with . <br /> sampling of first encountered groundwater; sampling locations were selected both inside <br /> and outside of the known dissolved plume to determine extent of plume migration. <br /> 2) Soil investigation of deep zone following first groundwater sampling, drilling will continue <br /> for an additional 20 to 40 ft depth below the shallow zone to collect two continuous cores <br /> from the deep zone. <br /> 3) LNAPL recovery well improvements included overdrilling recovery wells RW-1 through <br /> RW-4 and reconstruct them with larger diameter well and install two additional recovery <br /> wells and continue to weekly skimming and bailing product recovery. <br /> 4) To provide the Regional Water Board with sump construction and future operation <br /> details for the four sumps located in the furnace building basement. <br /> While the WP Addendum proposed no changes to the groundwater investigation, there were <br /> modifications proposed for the soil investigation and LNAPL recovery wells. The proposed WP <br /> Addendum includes: <br /> KARL E. LONBLEV SCD, P.EI,CRa1R I PAMEIA C.CREE00N P.E.,BCEE,EXECUTIVE OFFICER <br /> 11020 Sun Canter Orale 4200,RancM COrrd{ova,CA 95570 I "W.Watgrboards.ca.gov/centrawalley <br /> W.Watarboards.ca.gov/Cantrawalley <br /> p4In.... YAVtP <br /> I <br />