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a , Public Works - 2 - 12 July 2017 1810 Hazelton Avenue Stockton, San Joaquin County The Addendum and 2 ' Addendum move some of the proposed locations presented in the Work Plan, in order to avoid vertical migration of petroleum hydrocarbons into deeper water in the CPT borings, and to better locate the proposed monitoring wells to properly monitor transition (MW-9 and MW-10) and compliance (MW-8) zones in relation to ozone injection. The 2'd Addendum supersedes the Addendum, and therefore, the Addendum is voided. Central Valley Water Board staff concurs with the scope of work as proposed in the Work Plan and 2nd Addendum, with the following comments: In the Work Plan, Condor proposes to advance the CPT borings to 80 feet bgs. However, in order to properly define the vertical extent of hydrocarbon impact to groundwater, please advance these borings until hydrocarbon impacts are no longer detected by in-situ tooling, or 80 feet, whichever is deeper. In the Work Plan, Condor does not propose collecting groundwater samples from the CPT borings. Condor proposes assessing impact to groundwater using only in-situ membrane interface probe and hydraulic profile tool (MIP-HPT) technology. For the purposes of confirmation, please collect at least two grab groundwater samples for laboratory analysis from each CPT boring: (1) at the depth of highest hydrocarbon impact to groundwater, and (2) at the maximum depth of hydrocarbon impact, as based on in-situ analysis. Please analyze collected grab groundwater samples for the same constituents analyzed during semi-annual groundwater sampling. By 27 October 2017, please submit a Site Assessment Report. Please include tables that present collected soil analytical data, as well as in-situ and laboratory groundwater analytical data. Please also include an evaluation of shallow soil data as compared to Direct Contact and Outdoor Air Exposure criteria presented in the State Water Resources Control Board's Low Threat Underground Storage Tank Case Closure Policy (LTCP). Central Valley Water Board staff have the following additional comments on the current status of the assessment and cleanup of the petroleum release from the Site: In a letter dated 27 July 2016, Central Valley Water Board staff requested submittal of a Notice of Intent (N01) Addendum. To date, the NOI Addendum has not been received. By 29 September 2017, please submit the requested NOI Addendum, with all additional information as requested in the 27 July 2016 letter. Ozone injection at the Site cannot commence prior to submittal of the NOI Addendum and subsequent issuance of a Notice of Applicability (NOA) by this agency.