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I I August 1999 • -AGE-NC Project No: 95-0109 Page 4 of 10 To prepare this estimate of hydrocarbon mass in soil prior to remediation and at,the present time, AGE made the-following assumptions; , Areas between adjacent sampling points'-with detectable hydro' ons!-are.impacted'at a.,# I . concentrations intermediate to those-detected"ire the sampled points: Average concentrations were visually,weighted,based'the liinited number of sampling points• ' and plotted on cross sections and subsurface maps.:' Mass calculations, conversion factors and assumptions are included in Appendix E. 2.8. MONITORING_WELL PURGE PROCEDURES On 17 March and 24 June 1999,'a Soli_nst water level meter was used to measure`the depth to ground• water in the monitoring wells relative to the.tops of the well casings (Table 3). For the March 1.999 ' ' monitoring event, each monitoring well and EW-1 were then.purged using a Grundfos pump or PVC bailer. Far the June 1999 monitoring event,.wells MW-6, MW-7, MW-8, MW-9, MW-11, MW-12' and MW-14,were purged using a Grundfos pump. Approximately three well-volumes ofwater,were removed from each well'during.purging. Temperature, pH -and conductivity. of the purge water were measured at regular purge-volume , intervals using,an ICM or-Hydac water analyzer and were recorded on field logs. The percent , dissolved'oxygen was measured in the final purged water of each well. Field data and work sheets ' .,are included in.Appendix-C-The purged water was placed in DOT-approved drums and stored on- , site. Due to the unusual,ground water gradient determined for the June 1999 monitoring event, the depth •to ground-water was remeasured..in wells MW-6.through MW=14 and EW-,1 on 30 July 1999(Table, 3). Y 2.9. COLLECTION'OF:GROUND WATER SAMPLES „ For both sampling events, the depth to water in each purged.well; except MW-2, was remeasured ' after-purging to ensure a minimum of 80-per.cent recharge prior'to sampling.. Water samples were _collected from'each purged well,using-disposable plastic bailers. Immediately upon retrieval, the samples were transferred int6.40=ml'EPA-approved VOA-vials'containing,0.5 Int 18% hydrochloric ' facid as a sample preservative.,.The samples were labeled, stored on-ice, and transported in a chilled container, under chain-of-custody,to MAI. All 'samples.were analyzed for: . Advanced GeoEnviron menial,Inc.