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2.7 Groundwater Sampling Procedure i 10 Groundwater sampling procedure is as follows: Arriving on site the stainless steel submersible PUMP/stainless steel bailer is assembled and the sampling equipment prepared. The wells are unlocked,opened,and depth to water is measured from the top of casing. ' As a matter of procedure,the following actions are taken to evaluate the presence of floating product,or third phase contaminant material on the groundwater. If field evidence suggests that ' floating product may be present(i.e.,the well has a strong odor of hydrocarbons and gasoline is observed on the water meter probe),then either a bailer or product/water interface meter is used to measure the thickness of floating product on the surface of the groundwater. In the event that floating product is present, that well would not be sampled unless specifically requested. ' into the well lowered to a depth of 6 to 8 inches above the bottom and The pump/bailer�s inserted , activated. Water flow is monitored visually for cloudiness and measured for flow rate,temperature, ' conductivity,and pH. At least three well volumes are purged from the well prior to sampling until pH,conductivity,and temperature had stabilized to ensure sampling from representative formation water. After stabilization of water parameters,the well is allowed to recharge. Prior to sampling the well,a bailer blank is collected by pouring water provided by the laboratory into the bailer and emptying it into a sample vial. Sampling is accomplished by using a stainless steel bailer attached to a coated, stainless steel cable. The bailer is slowly lowered into the well and carefully allowed to fill with water. After filling,the bailer is carefully raised from the well taking precaution not to agitate the contained water. An emptying device was coupled to the bailer and the water was slowly ' transferred into the sample container(40 ml VOA vials). The sample vials provided by the laboratory contain 4 to 5 drops of hydrochloric acid to retard possible biological degradation. The vial is capped,inverted,and tapped to check for air bubbles. After assuring that bubbles are not present,the vial is labeled and inserted into a closed-cell foam holder and placed in an ice chest,cooled to 4°Celsius,for transport to the laboratory. To monitor possible cross contamination from any source,a trip blank prepared from water provided by the lab,is carried throughout the sampling,storage,and shipping process. A chain of custody document is filled out which listed all samples collected,their date of collection, ttransfers of custody,and laboratory analyses requested. This document is used to track the samples and to ensure their integrity. ' Groundwater physical parameters including temperature,conductivity TO,and pH are measured and recorded in the field and are provided in report as field logs. The groundwater samples may be analyzed by Sherwood Laboratories of Hilmar,California and tested for benzene,toluene,ethylbenzene,and total xylenes(BTEX)by EPA method 602 and total petroleum hydrocarbons as gasoline(TPH-Gasoline)by EPA method 5030/LUFr. ' The detection limits for these analyses are as follows:benzene,toluene,ethylbenzene, total xylenes 0.3 pg/l,and TPH-Gasoline 50 pg/l. The laboratory data sheets are attached in Appendix B. ' 2.8 Soil Boring Installation The soil borings will be drilled using a continuous flight hollow stem auger to a total depth to be determined but not to intercept the groundwater. Soil cuttings will either be containerized in DOT