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3 2 MONITORING WELL INSTALLATION AND GROUNDWATER SAMPLING <br /> A new monitoring well, DMW-5, was installed directly above the former 500-gallon waste <br /> oil tank (Figure 2) After drilling and sampling to 71 feet bgs, the soil boring from DMW-5 <br /> (Figure 2) was converted to a monitormg well The monitoring well was constructed of 4 inch <br /> diameter flush-threaded schedule 40 PVC casing and twenty feet of horizontally machmed-slotted <br /> 0 02 inch slot well screen The screened interval was filter packed with a prewashed #3 lonestar <br /> filter sand A 2-foot thick bentonite seal was placed above the filter pack using bentonite pellets <br /> hydrated with detonized water The remaining annular space was backfilled with a three percent <br /> prehydrated bentonite/cement mixture placed by tren-unie method The casing was cut off dust below <br /> ground surface and fitted with an air-tight cap The well head was encased in a water-tight metal <br /> vault box Well completion data for this well are presented in Appendix C <br /> The well was developed by bailing and surging on prior to sampling The well elevation and <br /> location was surveyed by Earnest F Smith & Associates on June 26, 1995 Groundwater samples <br /> were collected and water levels were measured from the four existwg wells on May 2, 1995 and <br /> submitted to a DHS-certified laboratory (D&M Laboratories) Monitoring well DMW4 was <br /> resampled on May 26, 1995, and monitoring well DMW-5 was sampled after development on <br /> May 26, 1995 <br /> 3 3 LABORATORY ANALYSES <br /> All soil and groundwater samples were sent to a DHS-certified laboratory (D&M <br /> Laboratories, Petaluma, Califorma) for analysis Soil and water samples were submitted for the <br /> following tests <br /> • Total petroleum hydrocarbons as diesel (TPH-d) — Method 8015M, <br /> • Total petroleum hydrocarbons as gasoline (TPH-g) — Method 8015M, <br /> • Benzene, toluene, xylenes, and ethylbenzene (BTXE) — Method 8020A, <br /> • Volatile halogenated hydrocarbons — Method 8010A, <br /> • Waste Extraction Test (deionized water) — method described in California Code of <br /> Regulations (CCR) Title 22, §66700 for extraction only, and <br /> • Senuvolatile organic hydrocarbons — Method 8270M <br /> The amended Work Plan (Appendix B) describes the rationale for the soil analytical program <br /> In order to evaluate the residual mass of TPH-impacted soil at the site, 12 samples were collected <br /> SAC156 14 5 <br /> DAMES & MOORE <br />