GENERAL33947 - Laserfiche WebLink

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