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SOP-010 Standard Operating Procedure <br />Well Construction Page 9 of 11 Revision No. 0 March 2020 <br /> <br />Sharpe Army Depot <br />3. Traditional Filter Pack. The screen and casing are inserted into the borehole, and the sand is poured <br />into the annular space surrounding the screen and casing. Occasionally, it may be difficult to <br />effectively place a filter pack around shallow open boreholes due to collapse. This method requires <br />more sand than the "inner filter pack". As the filter pack is placed, it mixes with the muddy water <br />in the borehole, which may increase the amount of time needed to purge the well to an acceptable <br />level of turbidity. <br />4. Double Filter Pack. The borehole is advanced to the desired depth. As with the "inner filter pack," <br />the well screen is filled with filter pack material and the well screen and casing inserted until the <br />top of the filter pack is at least 6 inches below the water table. Filter pack material is poured into <br />the annular space around the well screen. This type of temporary well construction can be effective <br />in aquifers where fine silts or clays predominate. <br />5. Well-in-a-Well. The borehole is advanced to the desired depth. At this point, a 1-inch well screen <br />and sufficient riser is inserted into a 2-inch well screen with sufficient riser and centered. Filter pack <br />material is then placed into the annular space surrounding the 1-inch well screen, to approximately <br />6 inches above the screen. The well is then inserted into the borehole. <br />4.6.4 Temporary Well Decommissioning <br />Temporary well boreholes must be decommissioned after sampling and removal of the screen and riser. Backfilling the holes with cuttings for shallow holes in uniform materials with expected low contamination levels. If waste materials were encountered or a confining layer was breached, then the use of cuttings would not be permitted. If the borehole cannot be backfilled with the soil cuttings, then reference the Site Waste Management Plan regarding the disposal of the cuttings as IDW. <br />5.0 Records <br />Records generated as a result of the implementation of this SOP will be controlled and maintained in the project record files.