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TECHNICAL SPECIFICATIONS <br />the GCL is hydrated when no confining stress is present, it may be necessary to remove and replace the <br />hydrated material. The GCL supplier should be consulted for specific guidance if premature hydration <br />occurs. <br />G. When a textured geomembrane is installed over the GCL, a temporary geosynthetic covering known as <br />a slip sheet or rub sheet should be used to minimize friction during placement to allow the textured <br />geomembrane to be more easily moved into its final position. <br />H. Although direct vehicular contact with the GCL is to be avoided, lightweight, low ground pressure <br />vehicles such as four -wheel all- terrain vehicles (ATVs) may be used to facilitate the installation of any <br />geosynthetic material placed over the GCL. The GCL MANUFACTURER or CQA MONITOR <br />should be contacted with specific recommendations on the appropriate procedures in this situation. <br />I. Soil cover, where applicable, shall be placed in a manner that prevents the soil from entering the GCL <br />overlap zones. Cover soil shall be pushed up slopes, not down slopes, to minimize tensile forces on the <br />GCL. <br />3.4 EARTHWORKS <br />A. Any earthen surface upon which GCL is installed shall be prepared and compacted in accordance with <br />the SPECIFICATIONS and DRAWINGS. The surface shall be smooth, firm, and unyielding, and free <br />of vegetation, construction debris, sticks, sharp rocks, void spaces, ice, abrupt elevation changes, <br />standing water, cracks larger than one - quarter inch (0.25 in) in width, and any foreign matter that could <br />contact the GCL. <br />B. Immediately prior to GCL deployment, the subgrade shall be final- graded to fill in all voids or cracks <br />and then smooth - rolled to provide the best practicable surface for the GCL. Prior to smooth - rolling, <br />moisture shall be applied to the surface of the subgrade by a water truck or other means approved by the <br />CERTIFYING ENGINEER to facilitate hydration of the GCL upon placement. At completion of this <br />activity, no wheel ruts, footprints, or other irregularities shall exist in the subgrade. Protrusions <br />extending more than one -half inch (0.5 in) from the surface shall be either removed, crushed, or pushed <br />into the surface with a smooth -drum compactor. <br />C. On a continuing basis, the CQA MONITOR and INSTALLER shall observe acceptance of the <br />subgrade prior to GCL placement. Thereafter, it shall be the INSTALLER'S responsibility to indicate <br />to the CQA MONITOR any change in the condition of the subgrade that could cause the subgrade to <br />be out of compliance with any of the requirements listed in this section. <br />3.5 ANCHORAGE <br />A. The end of the GCL roll shall be placed in an anchor trench at the top of the slope or an equivalent run <br />out design shall be utilized. When utilizing an anchor trench design, the front edge of the trench should <br />be rounded so as to eliminate any sharp corners. Loose soil shall be removed from the floor of the <br />trench. The GCL should cover the entire trench floor but shall not extend up the rear trench wall. <br />3.6 SEAMING <br />A. The GCL seams are constructed by overlapping adjacent panel edges and ends. Care should be taken to <br />ensure that the overlap zone is not contaminated with loose soil or other debris. <br />B. Longitudinal seams should be overlapped a minimum of six (6) inches for Bentomat ST, or per the <br />MANUFACTURER'S recommendations for an approved equivalent GCL. If the GCL is <br />manufactured with a grooved cut in the nonwoven geotextile that allows bentonite to freely extrude into <br />the longitudinal overlap, then no bentonite- enhanced seam is required for this overlap. If the GCL does <br />not have a grooved cut in one of the nonwoven geotextiles in the longitudinal overlap, then longitudinal <br />bentonite - enhanced seams are required as described below. <br />C. End -of -roll overlapped seams shall be constructed with a minimum overlap of twenty -four (24) inches <br />for Bentomat ST, or per the MANUFACTURER'S recommendations for an approved equivalent GCL. <br />Geosynthetic Clay Liner (GCL) August 28, 2013 <br />02776.2-5 Revision 0 <br />S \Projects \1550 - CC &V Field Spit CQA PSES Bldg \8 0 Project Engineering and Design \8 2 Specifications\PSES Pipe Rack Liner Extension Specifications \02776 2 Geocomposite Clay <br />Liner doca <br />