Laserfiche WebLink
1 <br /> 8 January 1993 <br /> (GeoAudit CV 45-49C5-1. 10) <br /> Page 2 of 7 <br /> diesel and BTE&X. Gasoline and diesel were detected in the water <br /> ' sample, indicating that groundwater has been impacted by an <br /> unauthorized release of hydrocarbons. The procedures and results of <br /> this phase of assessment were described in more detail in the <br /> "Monitoring Well Installation Report" submitted to the PHS/EHD on <br /> by GeoAudit on 26 June 1992 . <br /> In October, 1992 , the PHS/EHD requested that additional monitoring <br /> wells be installed to define the contaminant plume and assess the <br /> extent of groundwater contamination. Two additional wells were <br /> installed and sampled in November, 1992, and this report presents <br /> ' the procedures used and results that were obtained. <br /> ' PROCEDURES <br /> DRILLING AND SOIL SAMPLING <br /> On 12 November 1992 , two additional monitoring wells were installed <br /> on the subject property. MW-2 was installed east of the former tank <br /> excavation; MW-3 was installed at the southwest corner of the <br /> ' property (see Figure 2 - Site Plan) . <br /> The borings were advanced to a depth of 54 feet using a truck- <br /> mounted 8-inch hollow-stem auger rig. The CME-75 drill rig and two- <br /> man crew were supplied by West Hazmat Drilling Corporation. <br /> Discrete soil samples were collected ahead of the drill bit at <br /> 1 five-foot intervals using a split-tube sampler loaded with three <br /> pre-cleaned 2 . 5 by 6-inch brass tubes. To avoid cross <br /> contamination, the sampling equipment was washed in a tri-sodium <br /> phosphate (TSP) solution and rinsed twice with water prior to each <br /> sampling run. <br /> For each sample, both ends of the lead tube were then covered with <br /> ' aluminum sheets, capped and sealed with tape. The samples were <br /> stored on ice pending transmission to a state-certified laboratory <br /> (Alpha Analytical Laboratories in Ukiah) . The samples were analyzed <br /> ' for total petroleum hydrocarbons (TPH as gasoline and diesel) and <br /> volatile aromatics (BTE&X) . <br /> Soil from the second brass tube was extruded and screened for the <br /> presence of organic vapors using a photo-ionization detector (PID: <br /> Thermo Environmental 580A, 10.0 eV, calibrated to isobutylene) . The <br /> soil was then described in accordance with the Unified Soil <br /> Classification System (see Boring Logs) . <br />