FIELD DOCUMENTS AND WORK PLANS 1991

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diameter continuous slot screen with 0.03 inch slots. The screen shall be located in the bottom 50 feet of the well , except for 5 feet of blank riser located below the screen (see Drawing G-3). The screen shall be provided• in 10 foot lengths. A threaded PVC cap shall be provided for the bottom of the well. A steel cap with access ports for a pump discharge pipe, electrical wiring and floats, and a sounding pipe shall be provided for the top of the well (see Section 2A-10). The steel cap shall push on to the top of the well casing and be secured to the well with a minimum of four screws. The steel cap shall be of sufficient strength to support a submersible pump and discharge pipe. A nominal 3/4 inch diameter, Schedule 40 PVC sounding pipe shall be furnished and installed in the extraction well from the surface to 2 feet above the pump intake. The PVC sounding pipe shall be installed so that it is easy to remove or change the length of the sounding pipe installed in the well . The PVC sounding pipe shall be joined by threaded flush joints. Joints shall not be formed using solvent welding or glue. The upper end of the pipe shall be so positioned that an electric sounder line may be easily inserted through the well cap, lowered, and read. The penetration of the sounding pipe through the well cap shall be water tight, and a screw on cap shall be provided to close the penetration for the sounding pipe. Centralizers shall be installed at 40 foot increments from the base of the well to the top. Monterey No. 3 washed silica sand or an equivalent approved by the Engineer shall be used as backfill around the screen section and shall extend a maximum of 2 feet above the top of the screen. The silica sand shall be placed in a slow steady stream around the screen section. 2A-7.03. Monitorino Tubes. The monitoring tubes shall be placed to a depth of 20 feet below the water table encountered at the time of drilling. Blank riser for the monitoring tubes shall be 2-1/2 inch (nominal ) diameter (2.875 inches O.D. , 2.3 inches I .D. ) , schedule 80 aluminum pipe. Screen shall be 2-1/2 inch (nominal) diameter, schedule 80, NSF tested and approved PVC pipe with 0.01 inch factory slots. The screen length shall be 15 feet. The aluminum pipe shall be provided in 10 to 20 foot lengths. A threaded PVC cap shall be provided for the bottom of the screen, and a push on PVC cap shall be provided for the top of the aluminum riser. The aluminum riser sections and the aluminum risers and PVC screen shalt be joined using threaded flush joints. All the aluminum risers shall be new. Washed silica sand shall be used as backfill around the screen section and shall extend a maximum of 2 feet above the top of the screen section. The washed silica sand shall conform to gradation requirements of not less than 95 percent passing U.S. Standard sieve No. 8 and not (MARLEY SSFS ) 2A-9 (CONTRACT NO. 13) (11654.652 )