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MCCORMICK & BAXTER M11 /UTA <br /> TIM BRAY SFO <br /> • 02602 <br /> MONITORING WELL DRILLING AND DEVELOPMENT <br /> 1 . SCOPE <br /> 1.1 WORK INCLUDED: This section covers the work necessary to drill <br /> and develop the monitoring wells, construction of protective casing <br /> with grout seal, drilling and logging boreholes, installing casing, <br /> screen, gravel pack , and grouting inner seal , developing wells , and <br /> all other related work . <br /> 2 . MATERIALS <br /> 2 . 1 DRILLING MUD: Drilling mud, shall be only high-grade approved <br /> commercial clays, commercial clay products commonly used in the area <br /> r for water well drilling, or approved drilling additives . The <br /> drilling mud shall possess such characteristics as are required to <br /> adequately maintain the walls of the borehole, to prevent caving of <br /> the walls as drilling progresses, and to permit recovery of <br /> representative samples of drill cuttings . The Subcontractor shall <br /> remove any residual mud cake on the borehole wall during development <br /> of the well . <br /> 2 . 2 GROUT SEAL: Grout seal shall consist of a cement-bentonite <br /> slurry composed of 5 percent bentonite and 95 percent Type II <br /> Portland Cement with a water ratio of 14 . 5 to 15 . 0 pounds of solids <br /> per gallon of water . <br /> 2 . 3 -STEEL CASING: Steel casing shall be nominal 6-inch diameter <br /> Schedule 40 carbon steel pipe with flush coupled threads . Casing <br /> centralizers of solid construction shall be installed every 40 feet <br /> or as directed by the Engineer . Centralizers shall be of solid <br /> construction and be attached with steel screws or spot welded . <br /> Glues and solvents shall not be used to attach the centralizers . <br /> Casing that fails, collapses , or separates during construction shall <br /> be removed from the hole and repaired or replaced at Subcontractor ' s <br /> sole expense . <br /> 2.4 SCREEN: Screen shall be Schedule 40 S stainless steel <br /> "continuous wire-wrap" type with flush coupled threads , factory <br /> wound with ends sealed with standard stainless steel well bottom <br /> cap. For bidding purposes, screen shall be assumed to have 0 . 020- <br /> inch slots with an area of 52 . 9 square inches per foot of 6-inch <br /> screen. Slot opening may be modified by the Contractor as required <br /> to suit individual wells . <br /> 2 . 5 GRAVEL PACK: Gravel pack shall be a clean washed monterey <br /> sand. For bidding purposes, sand size shall be assumed as 8X16 <br /> monterey sand. Material may be modified by the Engineer to suit <br /> individual wells. <br /> M11701 .D0 MAY 29, 1987 <br /> 02602 1 MONITORING WELL DRILLING <br /> AND DEVELOPMENT <br /> 4 <br />