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REG 603 UPDATE-8 7/17/92 performed on the monitoring wells (May 25, 199D) indicated hydraulic conductivities (K) , ranging from highs of 45 43 and 33.48 feet/day at MW9 and MW1 respectively, to lows of 0 52 and 1 99 feet/day at monitoring wells MW2 and MW10 respectively. These drastically different K values (in the above mentioned wells) along with the monthly depth to ground water measurements help determine if the ground water beneath the site is in a recharge or discharge cycle If the ground water surface shows flow occuring from MW1 towards MW2, a recharge cycle is occurring If the ground water surface shows flow occuring from MW2 towards MW1, a discharge cycle is occurring. Measurements obtained on March 10, 1992, (Figure 4A) , show a flow direction to flow radially from MW3 with a pronounced valley forming from MW2 towards MWl This figure represents a continuation of the February period of discharge. The dome of ground water that has formed around MW3 and MW10 can be attributed to two factors, the slower recovery of the silty clayey sands and also to vapor extraction vacuum at the wells pulling the ground water up the wells Figure 4B, represents the ground water gradient derived from • measurements obtained on June 18, 1992. During this time no vacuum was being exerted from the vapor recovery system to the monitoring wells. This figure indicates the continuation of the discharge cycle, valleys forming at MW5 and MW9 2.2 GROUND WATER QUARTERLY SAMPLING Ground water samples have been collected since December 9, 1988, see Table 1. These samples were collected by a WEGE geologist and "Chain of Custody" hand delivered on ice to a state certified testing laboratory (McLaren Analytical or Chemtech (MATRIX) Analytical Laboratories) for chemical analyses These samples were analyzed for TPH, and BTEX concentrations using EPA Methods 8015 and 602 respectively Since diesel has never shown up in the sample results, the samples obtained from 11/27/90 and later were analyzed using EPA methods 5030 and 602 for Total Fuel Hydrocarbons and BTEX, see Appendix B. Complete chemical results are presented in Table 1 of this report 2.3 SAMPLING PROCEDURES Prior to opening the air/water tight well cap a vacuum reading is obtained from the well using a monometer calibrated in millimeters (mm) of water. This reading is then converted to feet vacuum at the well, see Table 1 Immediately once the air/water tignt cap is removed, before water "purging" or sampling has commenced, a ground water interface probe (resistivity meter) is lowered into • each well and depth to water measurements are recorded. Next, a PAGE 3