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I5.0 GROUNDWATER GRADIENT AND FLOW DIRECTION Groundwater depths were measured in each well, prior to purging and sampling on June 19, 1999 Depths were measured relative to the north side of the top of each well casing The monitoring well top-of-casing (TOC) elevations were surveyed relative to an arbitrary benchmark (chiseled square set at southeast corner of residence, assumed elevation of 100 00 feet) on February 19, 1999 by Quartaroli & Associates In each well, groundwater depth was subtracted from the respective well casing elevation to establish a groundwater elevation Cumulative groundwater elevation data is summarized in Table 3 On the basis of the June 19, 1999 groundwater measurements, groundwater flows to the east- southeast with a gradient of 0 04 Figure 3 presents a Potentiometnc Surface Map for the June 1999 groundwater monitoring event 6.0 GROUNDWATER MONITORING WELL SAMPLING BSK p sampling performed well sam lin activities on June 19, 1999 Prior to purging of the wells for sampling, water from each well was observed for floating product, product sheen, odor, color and clarity Monitoring wells were then purged of at least four well-casing volumes Measurements of temperature, conductivity, and pH were recorded to evaluate equilibrium pnor to sampling • Subsequent to purging, each monitoring well was allowed to recover, then water samples were collected from each well using a clean disposable bailer The samples were labeled, placed in an ice chest cooled with "blue ice", and submitted to a State-certified analytical laboratory for chemical analysis of TPHg, BTEX, and MTBE by EPA Method 8415/8020 (Modified) and fuel oxygenates by EPA Method 8260 Equipment used during purging and sampling activities was cleaned with non-phosphate detergent wash and rinsed prior to use at each well location The purged groundwater was stored in appropriately labeled 55-gallon drums at the Site Water Sampling Logs are included in Appendix A 7.0 ANALYTICAL RESULTS f analytical results for the second quarter of 1999 are resented in the following A summary o yt q p Table A A cumulative summary of quarterly monitoring analytical results is presented in Table 2 Laboratory Data Reports and Chain-of-Custody documentation are included in Appendix B Qemterly Montmmng Rq)W 07400178-Second Qoaner 1999 3