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Monitoring Well Installation Report Page 3 „h Appendix A f Project No.336.2 November 13, 1995 j 2.5 Sample Analysis Samples will be analyzed for benzene, toluene,ethyl benzene and total xylenes(BTEX),EPA methods 8020 and 602,and for total petroleum hydrocarbons as diesel,EPA method 3540/8015 modified. The analyses will be performed by Sherwood Laboratories of Hilmar.,California State Certification#1400. 2.6 Data Reduction Analytical data will be integrated with the geological data gathered during field investigation. Cross sections will be prepared to illustrate the stratigraphy and the distribution of soil contamination. The cross sections may be used for interpreting the extent of contamination. -:i 2.7 Groundwater Sampling Procedure 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. Ii 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. t;s The pump/bailer is inserted into the well,lowered, to a depth of 6 to 8 inches above the bottom and 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 i==1 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 I:- appropriate ro riate samP le containers (40 ml VOA vials/amber liters). 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.