ARCHIVED REPORTS XR0010233 - Laserfiche WebLink

Home Browse Search

Former Discovery Chevrolet June 6, 1997 Tracy,California Report of Additional Subsurface Investieation (OVM). No evidence of petroleum hydrocarbons were noted during drilling of the monitoring wells. The soil boring logs containing soil descriptions are included as Appendix D. Upon completion of drilling, a 2-inch inside diameter (ID) polyvinyl chloride (PVC) monitoring well was constructed in borings MW-4 and MW-5. The hand borings SA through SK were conducted by Horizon personnel to a depth of approximately S feet bsg. Borings MW-4 and MW-5 were each advanced to 20 feet bsg. The locations of the borings are shown on Figures 2 and 3. Hand borings SA through SK were backfilled with hydrated bentonite pellet hole seal and a 6-inch thick asphalt surface seal was installed to existing grade. Sediments encountered during drilling consisted primarily of clay to sandy clay from approximately surface grade to the total depth of the borings. The sediments from the borings were classified using the Unified Soil Classification System (USCS). A copy of the USCS is shown on the Boring Log Symbol Key in Appendix D. Soil cuttings generated during drilling operations were stockpiled on and covered with plastic and left on site until subsequent disposal. Four soil samples were collected from the stockpile, composited at the laboratory, and analyzed for gasoline hydrocarbons (Table 1). Monitoring Well Installation The boxings MW-4 and MW-5 were completed as 2-inch ID groundwater monitoring wells. The groundwater monitoring wells were completed to a depth of approximately 20 feet bsg. The lower portion of the groundwater monitoring wells were constructed of 13 feet of 2-inch ID schedule 40 PVC well screen with 0.020-inch slots and 2-inch ID blank PVC casing was extended to the surface in each of the wells. The annular space adjacent to the well screen portion of the wells was backfilled with#3 Monterey sand to approximately 2 feet above the screened intervals. An approximate 1 foot thick bentonite seal was placed at the top of the '? sand pack in all the wells, and a mix of bentonite/cement slurry was used to complete the 3001-1 l.rpt 4 HORIZON ENVIRONMENTAL INC.