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•r t •S. Gemini Petro ra hic investl ations B. DRILLING AND SOIL SAMPLING The subsurface conditions at the subject site were investigated on 9 November 1990, utilizing a rotary rig equipped with a six-Inch hollow stem auger. GPI personnel supervised the placement,drilling,sampling,and classification of the test borings. Soil samples were collected with a 2.5"OD modified California split-spoon sampler which was driven through the soil formation by a 140-pound weight dropped from a standard height of 30 Inches.The number of blows required to drive the soil sampler six Inches was recorded on the boring logs as a measure of the resistance to penetration of the boring material. The following soil handling procedures were followed In sequence for the boring advanced and sampled: • Sampling equipment and brass tubeswerecleaned with aTSPsolution and rinsed with delorized water before sampling to reduce potential of cross contaminatlon.Clean disposal gloves were used for the handling of each soil sample. a The bottom brass tube was reserved for further laboratory analysls. The Solis were classified using the Unified Soll Classification System(ASTM 2487),and the tube ends were wrapped with aluminum foil and capped, sealed with duct tape, labeled,and stored In a cooler(4°C),to be delivered to a state certified laboratory for analysis under chaln-of-custody protoco€. The portions of the soil sample recovered In the additional two tubes were also classified and noted for any contamination and/or changes in lithologies. Total sample recovery was denoted on the boring logs. e Portions of the soil sample recovered In the nose cone of the sampler was emptied Into a zlplock baggfe and sealed. Upon completion of each boring,the concentration of volatile hydrocarbons was measured utilizing a HNU Photoionizatlon Detector(PID). The reading for each samples were recorder on the boring logs. „x o Soil cutting from the dr€iling operation were transferred to metal drums(currently stored on site), o All downhole drilling equipment was pre-cleaned with a steam/pressure washer prior to drilling of individual borings.Rinsate water was collected in a steel trough and pumped into a 55 gallon drum upon completion of the soil borings(currently stored on alte). • The augers and other downhole equipment were steam cleaned prior to leaving the site.The steam cleaning rinsate was collected in a steel trough and pumped Into drums for storage. _ B. SITE FIELD EXPLCRATfON Subsurface conditions were Investigated by drilling one borings in the location as shown In Figure 2(Site Plan). Boring placEment.downgradient of the recently excavated gasoline underground storage tank was designed - - - -- --- to Intercept possible contamination which laterally and vertically migrated from the excavated. The boring placement was modified due to interference from overhead power and telephone line located approximately along the property line. Boring 1 was drilled to 50 feet below grade, 10 feet below the maximum historic groundwater level (approximately 40 feet below grade at this site). Soil samples were collected,ata minimum,In 5 foot intervals or at changes In Ilthologies,starting at 5.5%approximately mid-tank level. Ten soil samples were collected 3