ARCHIVED REPORTS_XR0004388 - Laserfiche WebLink

Home Browse Search

Mr John Johnson October 18,1995 LOCAL TOPOGRAPHY,GEOLOGY AND HYDROLOGY Page 3 The site is relatively flat and level The surrounding area is flat, gently sloping towards the southwest at an approximate rate of 0.83 foot per 1,000 feet The site elevation with respect to mean sea Ievel (MSL) is about 35 feet. The shallow geology of the site is sands and silty sands, fine to coarse, as logged by Kleinfelder geologists when the wells were installed in March, 1987. Shallow groundwater was logged at 13.75 feet below grade surface at the same time Groundwater gradient measured by Parker Environmental in September, 1991, was toward the southwest METHODS AND PROCEDURES A work plan and site safety plan were prepared and submitted to the San Joaquin County Public Health Services, Environmental Health Division for review and approval to commence. The project scope included the drilling of four borings to collect 2 soil samples per boring The boring locations were chosen to be as close as possible to the location of the former UST excavation walls Monitoring well 4, the well down-gradient from the former UST excavation, was also sampled. Drilling and Soil Sampling The drilling and soil sampling took place on May, 19, 1992 The borings were drilled with a one-inch bit rotohammer through the asphalt and base rock, then by pushing a one-inch hollow by 4-foot long steel tubes though the soil No utilities or underground structures were encountered during the drilling All rotohammer bits and steel tubing was washed prior to drilling and between boreholes in buckets using Alconox cleaner, then rinsed twice in tap water. All used waters were retained in DOT 17H drums and remain on site Continuous samples of the entire soil column were extracted from a clear plastic disposable sleeve inside the steel tubing. The plastic sleeves were inspected for logging of soil characteristics Samples selected for chemical analysis were sliced out of the plastic tubing, the ends were covered in teflon tape and plastic caps The samples were then placed into a cooler with ice and chain of custody procedures and documentation were initiated (Appendix B Sampling Documentation). A photo ionization detector (PID) gauged for petroleum hydrocarbons was used while drilling and sampling to collect field data of soil contamination No hydrocarbons were detected in the field using the PID No gasoline odors were noticed during the drilling and sampling Parker Environmental Services, 190 East 7th Street, Pittsburg, CA 94565-2317 Phone (510) 439-1024 Fax (510) 439-2566