COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

*i CONDOR EARTH i 188 Frank West Circle,Suite I Stockton,CA 95206 209.234.0518 Fax 209.234.0538 CONDORwww.condorearth.com January 29, 2019 Aimee C. Phiri Water Resources Control Engineer Central Valley Regional Water Quality Control Board 11020 Sun Center Drive,#200 Rancho Cordova,CA 95670 Subject: Addendum to Revised Work Plan for Additional Site Investigation dated February 27,2018 Former Helena Chemical Facility,2245 West Charter Way, Stockton, CA Condor Project No. 6847A Dear Ms. Phiri: Condor Earth (Condor) has prepared this Addendum to the Revised Work Plan for Additional Site Investigation (Work Plan) dated February 27, 2018, to address additions to the scope of work associated with the ongoing subsurface investigation activities at the former Helena Chemical Facility (Site) located at 2245 West Charter Way, Stockton, California (Figures 1, 2, and 3, attached). This Addendum was prepared at the request of Ms. Beverly Garcia of Raymond Investment Corporation, the property owner, and in response to your letter dated November 27,2018,which directed submittal of an addendum for step- out borings to delineate 1,2,3-Trichloropropane(TCP)and nitrate concentrations at the Site. The Work Plan described the drilling and sampling of additional soil borings and groundwater monitoring wells across the Site to evaluate the extent of 1,2,3-TCP and nitrate beneath the Site. The Work Plan was approved by the Central Valley Regional Water Quality Control Board(Central Valley Water Board) in a letter dated March 15, 2018. Condor executed the work described in the Work Plan in June 2018 and submitted the Site Investigation and Well Installation Report on October 3, 2018. The findings of the investigation are summarized as follows: 1. Nitrate as nitrogen (Nitrate-N) in groundwater has essentially been defined to the west (previous grab groundwater samples), to the south (well MW-4), and to the southeast (well MW-5). The greatest concentrations of Nitrate-N in groundwater are in the area near the former liquid fertilizer tanks and along the northern fence line of the property. 2. 1,2,3-TCP in shallow groundwater occurs primarily along the northern property boundary but does not extend a significant distance to the southwest (MW-2) or south-southeast (MW-4). The concentration also appears to attenuate northwest of boring B42(lower concentrations in B43)but is not fully defined to the north and east. 3. 1,2,3-TCP in groundwater does not extend south and/or northeast of well MW-3;the concentrations in well MW-3 have been below the MCL of 0.0050 micrograms per liter (gg/L) in four of six samples collected from the well.