Laserfiche WebLink
Soil & Groundwater Investigatiorb - 5 - 28 June 2006 <br /> Mountain House Sites #4 and #5 <br /> Mountain House, San Joaquin Co. <br /> Conclusions <br /> Review of the Site #4 reports, indicates the extent of impacted soil and groundwater <br /> associated with the OVP has been adequately delineated and additional investigative work is <br /> not needed at this time. The findings indicates that soil and groundwater impacts are limited <br /> in extent to less than 150-feet in width and 44-feet vertically, and the source of crude oil leaks <br /> —the former OVP, has been removed. Soil and groundwater impacted by TPHc is contained <br /> beneath Byron Road and/or within the current pipeline corridor. <br /> The removal of impacted soil containing concentrations of hydrocarbons may not be feasible <br /> given that the majority lies beneath Byron Road or the pipeline corridor. <br /> Review of the data indicates that the residual petroleum hydrocarbons in soil do not result in a <br /> significant source of TPHc constituents to groundwater. Due to the limited size of the impacts, <br /> the residual hydrocarbons are not anticipated to pose a threat to the beneficial use of <br /> groundwater in the area. <br /> Residual PAHs were less than their respective PRGs and are not considered a risk to human <br /> health. The residual hydrocarbons in the underlying soils will naturally degrade and the <br /> human health risks are at acceptable levels. <br /> A final determination for Site #4 cannot be made until a human health risk screening <br /> evaluation is completed and submitted for review. <br /> Similarly, it appears that impacts from TPH in soil has been defined and limited in extent to <br /> beneath Byron Road and/or within the pipeline right-of-way corridor next to Byron Road. <br /> However, groundwater has not been adequately delineated downgradient, north of boring <br /> MH5-7 and additional analysis is needed. <br /> agree that impacted soil conditions have been adequately defined. However, additional <br /> borings and analyses are needed to complete delineation of impacted groundwater north of <br /> boring MH5-7. SAIC recommended two additional borings north of MH5-7 to assess <br /> downgradient conditions of groundwater. <br /> CDHIRNOVPIMtn.House4&5 memo,Jun 06 <br />