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towards the pond) from the CMP riser. The depth of the excavation shall be no less than <br /> one-foot (1') below the top of the existing concrete apron. CONTRACTOR shall exercise <br /> appropriate care and caution in order to maintain the integrity of the CMP riser and of the <br /> horizontal CMP spillway. <br /> Six inches (6") of hydrated bentonite shall be placed on the base and on the sides of the <br /> excavation. The bentonite shall be sufficiently hydrated so that it slumps rapidly when <br /> placed on a board elevated to forty five degrees (45 0). Due to the fluid nature of the <br /> bentonite, it will be necessary to construct and place a form within the excavation prior to <br /> placing the bentonite slurry. <br /> Concrete, having a minimum compressive strength of 3,500 psi at twenty eight (28) days <br /> will be poured into the excavation after placement of the bentonite. Concrete may be <br /> mixed at the site, or may be delivered as 'ready mix' at CONTRACTOR'S option. If the <br /> concrete is mixed on-site, equipment and mixing procedures shall conform to ACI 301, <br /> Chapter 7. If'ready mix' is used, it shall be mixed and transported in accordance with <br /> ASTM C 94. Concrete shall be thoroughly compacted by means of a suitable mechanical <br /> vibrator. <br /> Upon completion of concrete curing, the dirt excavated from the embankment shall be <br /> replaced on top of the new concrete. The material shall be replaced in such a manner so <br /> that the slope of the embankment is returned to its original condition, and so that the top of <br /> the CMP riser is six inches (6") above the elevation of the embankment slopes. The fill <br /> shall be mechanically compacted during placement. <br /> - A hinged steel grate shall be placed over the top of the CMP riser. The grate shall be <br /> constructed using 1-1/4" structural rebar welded on eight inch (8") centers in both <br /> directions. Two (2) extra heavy duty hinges, having non-removable pins, shall be welded <br /> to the CMP riser and to the steel grate cover on the uphill side of the riser. A hasp, <br /> constructed of 3/8" steel, and having a circular hole of Y2" diameter,shall be welded to the <br /> CMP riser and the steel grate on the down.hill side of the riser. <br /> Measurement and Payment <br /> There will be no measurement for payment. Payment for this task will be reflected in a lump <br /> sum bid under Item 3 on the Bid Schedule. This lump sum bid will cover all costs for cutting of <br /> the CMP riser, offsite disposal of the excess CMP material, excavation of the embankment, <br /> form construction, purchase and installation of the bentonite, purchase and installation of the <br /> concrete, backfilling and compaction over the concrete, construction and installation of the <br /> hinged steel grate. Payment shall be as this task is completed and approved by the PROJECT <br /> MANAGER. Such payment shall be considered full compensation for all labor, materials, <br /> equipment and all other items necessary and incidental to the completion of Task 3, Sediment <br /> Pond Dewatering Device Repair. <br /> Task 4 Sealing Sediment Pond <br /> In order to minimize the infiltration of water from the sediment pond, bentonite will be placed <br /> within the pond. Bentonite shall be placed on the base of the pond and up the side slopes to <br /> the elevation of the lowest inlet of the CMP riser. The area of the pond to be affected by this <br /> Task is estimated to be fifteen feet (15') in width and three hundred feet (300') in length. <br /> CONTRACTOR shall ensure that the pond is free of water prior to initiating this Task. Upon <br /> 5 <br />