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No Further Action Required Request Report
<br /> Mountain House Development Site#5 September 15,2011
<br /> not a component of any previous investigation; therefore, groundwater elevations have not been
<br /> ' calculated.
<br /> 10. Provide tabulated results of all sample analyses, including the sampling method and
<br /> detection limits. Analytical results must include TPH and BTEX constituents, lead,
<br /> MTBE, EtBE, TBA, ETRE,DIPE, TAME, ethanol, methanol, ethylene dibromide, 1,2-
<br /> dichloroethane, and other constituents as indicated in Table#2 above. Provide any WET
<br /> or TCLP results.
<br /> Soil and groundwater analytical results for the COPCs (TPHc, BTEX, and PAHs) are included as
<br /> Appendix C. Lead, MTBE, EtBE, TBA, ETBE, DIPE, TAME, ethanol, methanol, ethylene
<br /> dibromide, and 1,2-dichloroethane are not COPCs, and were therefore not analyzed. WET and
<br /> TCLP tests have not been performed on soil samples.
<br /> 11. Discuss concentration and mass changes over time, and current concentrations of
<br /> contaminants remaining in groundwater at the site.
<br /> The hydrocarbons in the subsurface are not very mobile. At least 40 years have passed since the
<br /> pipelines were decommissioned; thus, the extent of residual hydrocarbons in the subsurface is
<br /> unlikely to increase. The concentrations of COPCs do not pose a threat to human health or the
<br /> environment, and it is expected that they will decrease to background levels over time.
<br /> 12. Provide isoconcentration contour maps of contaminants of concern to define the lateral
<br /> and vertical extent of contaminants remaining in soil and groundwater. The contour maps
<br /> should present an estimated "zero zone"of contaminant concentrations both on site and
<br /> off site.
<br /> SAIC compared the soil and groundwater sample analytical results for the COPCs to the lowest,
<br /> most conservative ESLs, RSLs, and WQOs, and concluded that the lateral extent of crude-oil
<br /> affected soil and groundwater was delineated, as indicated on Figure 2.
<br /> 13. Provide a summary of the remedial method(s) used to clean the site. Include the
<br /> calculated zone of influence, assumptions used to design the remedial systems(s), and the
<br /> duration of remedial activities.
<br /> Remediation has not been implemented at the Site.
<br /> 14. Provide a discussion of whether background is unattainable using best available
<br /> remediation method(s).
<br /> Consistent with Section III.A through C of SWRCB Resolution No. 92-49, SAIC evaluated
<br /> available remediation technologies for potential applicability to sites associated with the former
<br /> OVP and TAOC pipelines. SAIC, in collaboration with Geomatrix Consultants, Inc.
<br /> (Geomatrix), prepared a report of findings (SAIC, 2005b). Available removal technologies were
<br /> compared to in-place management of separate-phase oil (SPO), using the evaluation criteria of
<br /> effectiveness, implementability, and cost. The removal technologies evaluated were bailing;
<br /> passive and active in-well skimming; belt skimmers; excavation; in situ flushing with surfactants
<br /> and co-solvents; vacuum-enhanced recovery (bio-slurping); groundwater drawdown pumping; in
<br /> situ heating at low and high temperatures; short-term, multi-phase extraction; and pressure-pulse
<br /> technology.
<br /> ' SAIC and Geomatrix found that very little of the SPO encountered at former TAOC sites is
<br /> available for recovery due to its high viscosity and the low hydraulic conductivity of fine-gained
<br /> t 9
<br /> SAIC
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