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Zr <br /> ' ,P - s � 2� <br /> 'J- .yam.-;�...�'-..- " e, a .s '£„" �' F•., y <br /> w <br /> 7 <br /> GASCO Oil Company December 11, 1990 <br /> Quote No.8115G(Revised) Page 2-3 <br /> with approximately 35 feet of screen, the actual screened interval will be determined in <br /> the field. <br /> -� The wells will be constructed of 4-inch-diameter, Schedule 40, blank and slotted, flush- <br /> threaded polyvinyl chloride (PVC) pipe; no glues or solvents will be used in well <br /> construction. A 35-foot-long PVC well screen with three rows of 0.020-inch slots will <br /> —� be used. After the borings are drilled to the desired depth, the PVC casing will be <br /> installed through the hollow-stem anger. The sand pack will be slowly poured around <br /> the screen to approximately 2 feet ab.;ve the slotted screen section, where a bentonite <br /> seal will be placed and hydrated. The remaining portion of the annular space will be <br /> filled with neat cement and bentonite grout. The top of the well will be set in a traffic- <br /> rated box at grade with a locking cover to provide security. <br /> Well Development <br /> After construction, the four new monitoring wells will be developed by manually <br /> surging and mechanically pumping the groundwater to (a) remove residual silts and <br /> clays Ieft from the drilling and (b)improve the hydraulic conductivity between the well <br /> and the natural formation. After development, the wells will be allowed to recharge <br /> for approximately 72 hours, enabling Exceltech to collect a representative water <br /> sample. If the wells are low producing,samples will be.collected 4 hours after purging. <br /> Water collected during well development will iie'placed in properly labeled drums and <br /> left on-site until laboratory results are completed. The client is responsible for the <br /> disposal of ail drummed water. Exceltech can assist for an additional fee based on time <br /> and materials. <br /> SUrveyin� ' <br /> I Well casings will be surveyed to mean sea level to obtain accurate data and determine <br /> groundwater flow direction. The survey will be conducted with modern surveying <br /> equipment and methods to ensure accuracy so that the plot pians will portray the data in <br /> a useful manner. <br /> Groundwater Sampling <br /> Exceltech will collect groundwater samples from the four newly installed monitoring <br /> wells for laboratory analysis. Before groundwater sampling, an Exceltech geologist <br /> will field-check each monitoring well for free-floating product by collecting a sample' <br /> in a clear acryli,. bailer or by using an electric interface probe. Where no floating <br /> product is observed, the well will be purged of at least 4 well casing volumes of <br /> groundwater before sampling. Samples will be (a) collected with a clean bailer, (b) <br /> transferred to appropriate laboratory-supplied bottles, (c) labeled, (d) Iogged on chain- <br /> _l <br /> of-custody forms, and (e)placed in a cooler for transport to a state-certified laboratory. <br /> 1 ,- <br />