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r 77 J. MM H. KLEINFELDER &ASSOCIATES File: 24--2045-2/29:795 December 31, 1986 Page 4 o A two-foot bentonite plug will be placed above the sand pack to provide a seal against surface water infiltration. o The remaining annular space will be filled with cement/bentonite grout to the surface. a Each well will be secured inside a cement utility box set flush to the ground surface. 3,5 Monitoring Well D v loRment and SamplingPro-cedures All three monitoring wells will be developed after installation. Each well will be first sampled with a clear acrylic bailer to visually inspect the sample for a product layer or sheen. If no product layer or sheen is observed on the water samples, the wells will be developed with a surge block/air lift development tool. Surging with the tool along the screened interval of the well will be performed to draw the sediment from the formation into and out of the well, and to set the sand pack. The sedirr2nt laden water will be air lifted from the well at a rate of - approximately 4.75 gallons per minute (gpm). Each well will be developed until the discharge water runs relatively clear of fines. Approximately 5 to 10 well •iIolumes will be removed from each monitoring well. After the wells have been developed, the formation will be allowed to stabilize for approximately one week. The depth to the static water level will be measured and then the well will be purged and sampled with a submersible pump. During the purging of the wells, field parameters (ph, conductivity, temperature) will be monitored. Samples will be collected after the field parameters have stabilized, normally requiring three to five well purge volumes. The sample bottles will be immediately sealed after collecting a,sample and placed in an iced cooler. At the end of the field day,-- the-waLcr samples will be delivered to a state/EPA certified analytical laboratory under chain-of-custody. To prevent cross-contamination, all developing and sampling equipment will be steam cleaned prior to use in each monitoring well. Additionally, a trisodium phosphate solution and clean water will be pumped through the sampling equipment prior to the collection of subsequent water samples. j&___MQ_niror!ng Well El v i n vev The relative elevations of the top of the two-inch INC casings will be --- "- -. surveyed--for.-, --- - - --the three- monitoring wells--The-casing-elevations-will-.be-- :- ---- ----- -- - --- tied into an assumed .elevation or a nearby county or USGS benchmark. Depth to the static ground water table will be measured from the top of each PVC casing. The depth to water will then be subtracted from the elevation of the top of the well casing to provide a relative water table elevation for each monitoring v:,ell location and to assess the approximate local ground water gradient direction. o