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Phase I Environmental Site Assessment Proposed Mountain House Preschool and Multi-Purpose Buildings 54 West Conejo Court,Mountain House,CA Page 5 hydrocarbons)to soil and groundwater. Shell removed contaminated soil from the pipeline alignment in the southwestern portion of Neighborhood E (northern adjoining property) and investigated the northern portion of Neighborhood C in 2003 and remediation of Neighborhood C was completed in 2007. Condor was retained by Shea Mountain House, LLC to provide environmental review of Shell's investigation and remediation activities in Neighborhoods C and D in 2006 through 2011. Shell continued remediation activities in Neighborhoods D and B under the oversight of the Central Valley Regional Water Quality Control Board(CVRWQCB). Portions of the remediation and subsequent investigations were also overseen by the Department of Toxic Substances Control(DTSC)where the pipeline alignment transected the High School in Neighborhood D. There were seven excavations conducted to remediate impacted soil in Neighborhood D. Excavations were completed until cleanup goals were achieved or to the maximum practical depth which ranged from 10-23 feet below ground surface (bgs). Cleanup goals were 5,000 milligrams per kilogram (mg/kg) crude oil and 5,000 mg/kg diesel. Shell excavated and disposed of approximately 93,000 cubic yards of soil impacted by petroleum hydrocarbons from Neighborhood D, installed 34 groundwater monitoring wells, and installed one soil gas probe in the vicinity of the school. Excavations 10-13 in Areas 6-7(immediately south of the High School)were excavated to 23 feet bgs and residual concentrations of crude oil ranged from 1,000 mg/kg to 3,300 mg/kg and diesel from 580 mg/kg to 2,000 mg/kg. The only excavation where remaining hydrocarbon concentrations exceeded the cleanup goal was in Area 11 (southeastern corner of Neighborhood D) which was excavated to approximately 23 feet deep and had residual crude oil concentrations ranging from 110 mg/kg to 5,100 mg/kg and diesel concentrations ranging from 1.7 mg/kg to 3,100 mg/kg.Area 11 was discordant with the pipeline alignment and appears to have been a disposal trench used in the late 1940s or early 1950s to purge the pipelines. All excavations were backfilled with engineered fill. One year of quarterly groundwater monitoring results showed no detectable constituents in any of the Site monitoring wells.A soil gas survey was conducted and no excess risk to future site occupants was revealed from the soil gas sampling results.Upon completion of investigation and monitoring activities, Shell properly abandoned the groundwater monitoring wells and soil gas probe. The CVRWQCB concurred with Shell that remaining concentrations of petroleum constituents in soil did not pose a threat to human health,the environment,or waters of the State,and issued a No Further Action (NFA) determination in a letter dated November 4, 2011. This case does not pose a risk to the Site. 3.2.2 SUMMARY OF DIELDRIN REMEDIATION(NEIGHBORHOOD C) Based on several environmental investigations conducted in Neighborhood C(western adjoining property), elevated concentrations of the organochlorine pesticide, dieldrin, were discovered in the southern portion of Neighborhood C. Shea Mountain House,LLC (Shea)entered into a Voluntary Cleanup Agreement with DTSC in 2007 to engage DTSC oversight of remediation of the dieldrin. The selected remedy was soil removal and encapsulation beneath the southbound lanes of Great Valley Parkway on the far western margin of Neighborhood C.Remediation activities were conducted in accordance with the DTSC-approved Removal Action Workplan(RAW)prepared for Shea by Condor.Condor conducted environmental services for Shea in accordance with the RAW, including documentation of remediation activities, air monitoring, and soil sampling which will be documented in the Draft Removal Action Completion Report to be completed by Condor. The cleanup goal was 0.035 mg/kg dieldrin at the southern portion of the Site. The laboratory analytical results for a total of 62 final confirmation samples confirmed that the cleanup goal had been achieved, the soil remediation activities were complete, and DTSC concurrence and approval to proceed with mass grading in the remediated area was obtained on November 25, 2013. Approximately 77,000 cubic yards of dieldrin-impacted soil were ultimately removed and entombed beneath the southbound lanes of Great Valley Parkway. Site Certification by DTSC was granted in the fall of 2016. This location does not pose a risk to the Site. �a CONDOR