SU0008578 - Laserfiche WebLink

Home Browse Search

5.ENVIRONMENTAL CHECKLIST MOUNTAIN HOUSE NEIGHBORHOODS K AND L INITIAL STUDY 7.HAZARDS releases associated with this AST. However, under the ASTM standard,ASTs represent a"recognized environmental condition"because leaks from an AST could introduce petroleum hydrocarbons to soil and groundwater.A release from a 20-gallon AST, however,would be relatively minor and no staining or other evidence of a release were noted in the Phase l ESA(Condor,2004a). It is believed that the AST was removed in accordance with state and local requirements at the time the small garage was demolished. Soil and Groundwater Contamination Adjacent to Neighborhood L. Residual soil and groundwater contamination related to historical crude oil leaks from the abandoned OVP remains beneath portions of Byron Road and the adjacent railroad tracks.Three separate locations with petroleum hydrocarbon contamination (Chevron Mountain House Sites Nos. 1, 2, and 3)have been identified adjacent to Neighborhood L.The contamination has been detected along the Byron Road/Union Pacific Railroad corridor, and at an adjacent agricultural field(see Figure 5.7-1).The petroleum hydrocarbons in site soils and groundwater are considered to be highly immobile, limited in extent, and concentrated in close proximity to the abandoned pipeline. Following delineation of the areas of soil and groundwater contamination and a human health risk screening evaluation for these contaminated sites, the RWQCB determined that the residual levels of petroleum hydrocarbons in soil and groundwater do not pose a threat to public health or the environment under the existing and proposed site uses,and that no further action is required unless these areas are disturbed by subsurface excavation.Therefore,the potential health risks to future site occupants from residual soil and groundwater contamination associated with historical crude oil releases in the site vicinity are considered to be low. Based on the delineation of soil and groundwater contamination associated with Chevron Mountain House Sites 1,2,and 3, it appears that excavation and grading for Neighborhoods K and L would be unlikely to encounter soil and groundwater contamination originating from these sites. However,considering the long history of crude oil pipeline operations and leaks,there is a potential for contaminants to be encountered in the Neighborhood L areas bordering Byron Road. Exposure to these contaminants could potentially result in harmful health effects for construction workers, and an accidental release of contaminated soil or groundwater could result if precautions are not taken.This impact is potentially significant, but could be reduced to a less-khan-significant level with implementation of Mitigation Measure HAZARDS-1.This measure requires that if any indications of petroleum hydrocarbon contamination, such as stained soil or odors, are encountered during excavation or grading,the construction contractor must immediately notify the RWQCB and Chevron Environmental Management Company to investigate and ensure the proper handling and disposal of e contaminated material. Fuel-Related Pipelines. With implementation of the proposed project,the two existing fuel-related pipelines along Byron Road that border Neighborhood L would remain in their existing alignments. All development would conform to (gall 1) 5-9$