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r�e4a/.' <br /> February 20, 2014 <br /> Mr. Jim Barton, Engineering Geologist Our Ref: Siebold Construction <br /> Central Valley Regional Water Quality Control Board GHD Job No: 03009-10017-37060 <br /> 11020 Sun Center Drive, #200 Your Job No.: 129594 <br /> Rancho Cordova, CA 95670-6114 Your Ref: DGS-RESD Contract No. <br /> 3152182, Amendment 12 <br /> Subject: Cost to Closure Scope and Fee for Environmental Services at the Siebold Construction <br /> Property, Project Site "J", 820 S.American Street, Stockton,CA, CVRWQCB Case#390394 <br /> Dear Mr. Barton: <br /> GHD is pleased to submit this Conceptual Site Closure Plan (Plan) and cost to closure estimate to the Central <br /> Valley Regional Water Quality Control Board (CVRWQCB) as requested in your December 10, 2013 letter. This <br /> Plan provides a brief history of the work completed to date and a conceptual plan to obtain site closure through <br /> the State Water Resource Control Board's (SWRCB's) Low-Threat Closure Policy (LTCP)for the Siebold <br /> property located at 820 S.American Street, Stockton, California. The Plan is described in the scopes of work <br /> presented in this document and includes cost estimates associated with the implementation of the Plan.A <br /> portion of the Plan is currently funded under the DGS Contract Number 3152182, Amendment#12 while <br /> additional funding will be required to fully implement the Plan to obtain site closure.An estimated cost to closure <br /> spreadsheet is included that will separate the funded scopes of work and those where additional funding will be <br /> needed. The estimate includes a case closure evaluation, public notification addresses/property owners list <br /> (200-to 300-foot radius of the site), well destruction and waste disposal. Additionally, if unacceptably high <br /> residual concentrations of petroleum hydrocarbons in soil and groundwater continue to be documented at the <br /> site, then two (2) alternate tasks are proposed including a 60-day high vacuum dual-phase extraction (HVDPE) <br /> pilot test to provide soil and groundwater remediation at and near the source and four(4)additional quarters of <br /> groundwater monitoring, sampling, and reporting to document the results of the source remediation. The <br /> HVDPE is proposed to remove mass from the site to enable natural attenuation and the application of the LTCP <br /> to be utilized. The proposed scope of work and cost estimate is presented below. <br /> SCOPE OF WORK <br /> As requested by Mr. James Barton of the CVRWQCB, GHD will implement following scope of work: <br /> TASK 7 -EVALUATION OF SITE FOR Low RISK CLOSURE <br /> This Task will involve the review of available files and site data to evaluate for site closure using the <br /> recently adopted SWRCBS LTCP and Resolution No. 9249 if applicable. While the LTCP is being <br /> evaluated, the CVRWQCB has additional requirements for closure based on soil and groundwater mass <br /> estimates (prior to, removed by treatment and/or after treatment; time to reach Region 5 water quality <br /> goals and if the monitoring network does not provide adequate plume definition)then a fate and transport <br /> model may be required. This Task will be implemented once site conditions warrant. <br /> 1. Review available files and historical site data. <br /> 2. Discuss findings with the CVRWQCB. <br /> 3. If applicable, prepare a Site Closure Request in accordance with the SWRCB'S LTCP or an <br /> appropriate method. <br /> Deliverable: A Case Closure Report and upload data to GeoTracker. This report may be combined <br /> with a quarterly monitoring report. <br /> GHD Inc. <br /> 3831 N. Freeway Blvd Suite 220 Sacramento CA 95834 USA <br /> T 1 916 372 6606 F 1 916 372 6616 E sacramento@ghd.com W www.ghd.00m <br />