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• <br /> 3.3.4 Screen,Well Casing/Riser Pipe Placement <br /> The monitoring well screen length shall be determined by the Government,but not more than <br /> twenty (20) feet, with specified bottom cap securely attached, set to the appropriate depth. The <br /> bottom of the well screen shall be placed no more than 2 feet above the bottom of the drilled <br /> borehole. The screen and well casing sections shall be joined by flush threaded watertight joints. <br /> The well casing shall extend upwards from the screen to an elevation appropriate for the surface <br /> completion described in paragraph 3.3.8, Protective Cover Placement. <br /> The well screen and well casing shall not be dropped or allowed to fall uncontrolled into the <br /> borehole. The screen and casing shall be suspended at the surface during placement of the filter <br /> pack and annular seal. Screen and well casing shall be cleaned with high pressure hot water/steam <br /> just prior to installation; foreign material shall not remain on the screen and well casing before <br /> installation. The use of factory-sealed(plastic wrapped) screen, free from painted markings,does <br /> not waive requirements for pre-installation cleaning. Joints and fastenings shall be watertight and <br /> flush threaded;no solvent glue or set screws shall be used. A threaded cap shall be installed on <br /> the top of the casing. <br /> 3.3.5 Filter Pack Placement <br /> After the screen and well casing have been concentrically placed in the hole, the approved filter <br /> pack shall be constructed around the screen by filling the entire space between the screen and the <br /> wall of the hole over the selected screened interval. The lowermost 2 foot of filter pack shall be <br /> i placed in the boring prior to installation of the well screen. A tremie pipe having an inside <br /> nominal diameter of not less than 1 inch shall be lowered to the bottom of the annulus between <br /> the hole and well. The tremie pipe shall be cleaned with high pressure hot water/steam prior to <br /> each use. The tremie pipe shall be arranged so that water and filter pack material fed at uniform <br /> rates are discharged as the filter pack material fills the hole from the bottom up. The tremie pipe <br /> shall be raised at a rate that will keep the bottom of the pipe between 2 and 5 feet from the surface <br /> of the filter pack level at all times. <br /> Dumping filter pack material from the surface of the ground and agitating the well in an effort to <br /> settle the filter material will not be allowed. The filter pack shall be installed in 3 foot lifts until <br /> the filter pack has been placed 3 feet above the top of the screen in the monitoring well. The <br /> depth to the top of the filter pack shall be directly measured, and recorded. Any water added to <br /> the filter pack material shall be obtained in accordance with paragraph 3.2.3. Filter pack material <br /> shall be protected from contamination prior to placement by either storing it in plastic lined bags, <br /> or in a location protected from the weather and contamination on plastic sheeting. Filter pack <br /> material shall be transported to the well site in a manner which prevents contamination by other <br /> soils, oils, grease, and other chemicals. <br /> Augers shall be removed simultaneously with the above operation. Lifting of the well casing shall <br /> be minimized when withdrawing the augers. Filter pack material shall be placed in no greater than <br /> 02671-007 <br />