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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 °). 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 3l8" steel, and having a circular hole of/:" 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 6e 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 />