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Operations and Maintenance Plan <br /> Neighborhood C,Great Valley Parkway <br /> Mountain House,San Joaquin County,California <br /> Page 1-1 <br /> OPERATIONS AND MAINTENANCE PLAN <br /> NEIGHBORHOOD C <br /> GREAT VALLEY PARKWAY <br /> MOUNTAIN HOUSE, SAN JOAQUIN COUNTY, CALIFORNIA <br /> January 2017 <br /> 1.0 INTRODUCTION <br /> As part of the development of Mountain House, the land developers evaluated historic land use practices <br /> during the entitlement process. The southern portion of Neighborhood C was found to contain residual <br /> concentrations of a legacy pesticide, dieldrin, at concentrations above sensitive land use screening <br /> concentrations in shallow soil. Dieldrin is a chlorinated pesticide considered to be a probable human <br /> carcinogen. A Removal Action Workplan (RAW) was developed in 2007 to remove dieldrin-containing <br /> soil and place it beneath an arterial roadway in Neighborhood C. <br /> 1.1 PURPOSE <br /> This Operations and Maintenance Plan has been prepared at the request of California Department of <br /> Toxic Substance Control (DTSC). In 2013, dieldrin-containing soil was removed from the southern <br /> portion of Neighborhood C and placed in a pre-excavated encapsulation trench located beneath the <br /> southbound lanes of Great Valley Parkway(Site,Encapsulation Area). The purpose of this document is to <br /> present the procedure for the long term monitoring and maintenance of the Site. <br /> Completion of soil removal and capping activities were described in the Removal Action Completion <br /> Report dated October 4, 2016. The removal and capping activities were performed as described in the <br /> RAW dated July 9, 2007 by Condor Earth Technologies, Inc. (Condor). Site investigation and cleanup <br /> activities were performed under a voluntary cleanup agreement (VCA) (HAS-VCA 06/07-147-2A) <br /> between DTSC and Shea Mountain House,LLC (Shea). <br /> 1.2 SITE BACKGROUND <br /> Dieldrin was found to be present at elevated concentrations in the southern portion of Neighborhood C <br /> within the former Silva property. Shea entered into a VCA with DTSC in 2007 to engage DTSC oversight <br /> of remediation of the dieldrin-containing soil. The selected remedy was soil removal and encapsulation <br /> beneath the southbound lanes of Great Valley Parkway, between Mustang Way and Grant Line Road <br /> (Figure 2). <br /> The project proponent entity subsequently changed from Shea to Mountain House Developers, LLC <br /> (MHD). In 2013, Condor conducted environmental services for MHD in accordance with the RAW, <br /> including documentation of remediation activities, air monitoring, and soil sampling which has been <br /> documented in the Removal Action Completion Report, Neighborhood C (Hansen Village), Mountain <br /> House, San Joaquin County, California, dated October 4, 2016 prepared by Condor. The cleanup goal <br /> was 0.035 mg/kg dieldrin for the removal area. The laboratory analytical results for a total of 62 final <br /> confirmation samples confirmed that the cleanup goal had been achieved. The soil remediation activities <br /> were complete and DTSC concurrence and approval to proceed with mass grading in the remediated area <br /> was obtained on November 25, 2013. Approximately 70,000 cubic yards of dieldrin-impacted soil were <br /> ultimately removed and placed beneath the southbound lanes of Great Valley Parkway. <br />