WORK PLANS - Laserfiche WebLink

Home Browse Search

PES Environmental,Inc. Ms. Emily Cushman October 20, 2015 Page 2 PLANNED SOIL EXCAVATION Based on our current understanding of site conditions, PES plans to conduct soil excavation activities in the vicinity of the PG&E vault and vehicle fueling pad to remove readily accessible hydrocarbon-affected soil for future treatment and/or disposal. As shown on Plate 2, excavation is planned to commence in the vicinity of the PG&E vault and will extend in all directions until: (1) visual and field screening suggests that significant hydrocarbons are no longer present, (2) existing infrastructure is encountered making further removal impractical, or (3) excavation along the eastern face of the levee, in the opinion of the local reclamation district, will raise the risk to the structural integrity of the levee. Excavation depths will vary from 3 to 11 feet below ground surface depending on surface topography and location with respect to the suspected leak. It is anticipated that a representative from the reclamation district will be present on the site during excavation along the eastern face of the levee. Significant excavation below the water table is not anticipated as part of this removal action. Soil removal will be conducted by HAZWOPER-trained personnel using a small track-mounted excavator directed by a PES field engineer. The excavated soil will be placed on the vehicle fueling pad and then separately loaded, using a small loader, into a 5-cubic yard dump truck for transport to a designated on-site soil storage area. During the initial phases of excavation, clean overburden soil from the parking lot berm, that is removed to expose the pipe leak, will be staged immediately adjacent to the excavation and promptly replaced following removal of hydrocarbon-affected soil encountered beneath the berm in the release area. Fuel and sanitary sewer pipes encountered during excavation will be removed with the exposed ends of the pipes capped. It is PES understanding that these pipelines will be replaced once excavation and backfilling operations are completed. The remainder of the excavation will remain open and secured with a portable chain-link fence until the limits of soil removal and volumes of backfill materials needed are known. The excavation will be backfilled with import materials deemed suitable by the reclamation district. Excavation will be monitored and directed by a PES field engineer using visual cues and portable field screening equipment. Excavated soil will be moved to a stockpile storage area located approximately 100 feet south of the planned excavation area. This area, currently used for boat trailer storage, is paved and partially protected from westerly winds. Soil stockpiled in this area will be placed on 10-mil plastic sheeting and covered with the same as directed by Rule 4651 of the San Joaquin Valley Air Pollution Control District. Once covered, the soil stockpile will be inspected on a daily basis to insure integrity of the plastic sheeting and to replace/repair as necessary. Once the volume of hydrocarbon-affected soil is known, PES will work with the reclamation district to obtain suitable fill and procedures for backfilling the excavation. In addition to the planned soil removal activity, PES is also preparing a work plan for implementation of an investigation to assess the limits of the impact to the subsurface. The work plan will be presented to the CRWQCB for review and comment prior to 148400101W002.doe