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<br />SLURRY WALL RESERVOIR LINING SYSTEMS <br />TECHNICAL BRIEF <br />Introduction <br />Slurry walls are narrow trenches backfilled with low permeability material forming a barrier to the <br />movement of groundwater. The hydraulic barrier formed by a slurry wall can function as a <br />reservoir liner replacing the traditional slope embankment liner or earth dam. Slurry walls have <br />been successfully installed by Hall-Irwin/RMC on several reservoir projects in the Front Range area. <br />A carefully designed and constructed project will meet the State of Colorado's allowable <br />groundwater inflow requirement for issuance of an absolute storage right. <br />Construction of a slurry wall begins with the excavation of a narrow trench with vertical sides. The <br />trench is excavated using a specially fitted backhoe excavator or clam shell excavator. The narrow <br />vertical trench is held open by the thixotropic properties of the slurry which fills the trench during <br />excavation. The slurry consists of a mixture of powered bentonite and water. The primary barrier <br />to groundwater is formed when the slurry filled trench is backfilled with asoil-bentonite mixture. <br />The soil-bentonite backfill is heavier than the slurry, thus it flows to the bottom of the trench, <br />displacing the lighter slurry. <br />During construction, the rate of trench backfilling matches the rate of excavation. There is <br />generally 100 to 300 feet of slurry filled trench between the excavation face and backfill operation. <br />SLURRY LEVEL <br />,... i <br />PLACED BACKFILL <br />NO SCALE <br />SLURRY TRENCH LONGITUDINAL SECTI <br />