Laserfiche WebLink
... .. . <br /> rc� 3.0 PROCEDURES <br /> 3.1 Drilling and Sampling <br /> On June 20, 1994, one soil boring (B-1) was drilled at the site. The boring was drilled near <br /> the center of the former underground storage tank (UST), and advanced to a depth of 38 <br /> feet. Because hydrocarbon-impacted soil was encountered during the drilling of B-1, three <br /> monitoring wells were installed at the site. <br /> On August 30, 1994, three additional borings were drilled at the site to depths of 49 feet <br /> and completed as groundwater monitoring wells MW-1, MW-2 and MW-3. The locations <br /> of the borings are shown on Figure 2. <br /> ' I <br /> Each boring was drilled using a truck-mounted CME 75-HT drill rig. The drill rig and two- <br /> man crew were supplied by Mitchell Drilling Environmental (MDE) of Rancho Cordova, <br /> California, <br /> Samples were collected at five-foot intervals in each boring using a split tube sampler Ioaded <br /> with three clean, 2 by 6-inch brass sleeves. A 140-pound hammer was used to advance the <br /> - sampler 18 inches; the number of blows required to advance the sampler in 6-inch <br /> increments was recorded on the boring logs. All sampling equipment was washed in an <br /> Alconox solution and rinsed twice with water prior to each sampling run. <br /> For each sample, both ends of the lead tube were covered with aluminum sheets, capped <br /> and sealed with tape. The samples were then stored on ice and transported under chain-of- <br /> custody to McCampbell Analytical, Inc. (MAI) in Pacheco, CA. <br /> During drilling, auger returns were monitored for the presence of organic vapors using a <br /> photo-ionization detector (PID: Thermo Environmental 580A, 10.0 eV, calibrated to <br /> i isobutylene). Auger returns were then placed on plastic sheeting and stored on-site. <br /> 3.2 Logging <br /> Soil was extruded from the second brass tube and screened for the presence of organic <br /> vapors, using a PID, and the readings were recorded on the boring logs. The soil was then <br /> described in accordance with the Unified Soil Classification System (see Boring Logs, <br /> Appendix A). <br /> 3.3 Well Completion <br /> Borings MW-1, MW-2 and MW-3 were completed as a groundwater monitoring wells using <br /> a 2-inch diameter PVC casing with 0.020-inch slotted screen from 29 to 49 feet. The filter <br /> pack (#3 lonestar sand)was installed from 27 to 49 feet. Bentonite chips were used to make <br /> a two foot plug and the well was grouted to the surface with Portland cement. Boring B-1 <br /> Cmbg"l A.Q&--.Loc 4 <br /> PJkb..MEXOMS.pt L9Lb <br /> f <br />