875CONCRETE OUTLET STRUCTURE

875.1DESCRIPTION—This work is construction of a permanent concrete outlet structure for a stormwater

management facility and where applicable, the conversion to and from a temporary sediment trap or sediment basin.

875.2MATERIAL—

• Reinforcement. Section 709.1

• Steel Shapes. Section 1105.02(a)2

• Welding Material. Steel Shapes. Section 1105.02(t). Reinforcement. AWS D1.4 Structural Welding Code, Reinforcing Steel.

• Galvanizing. Section 1105.02(s)

• Anchor Bolts, Nuts and Washers. Section 1105.02(c)2.

• Wire Mesh. Steel Wire, No. 10 gage, with 1.5-inch square opening.

• Plywood. 3/4-inch thick, Alkaline Copper Quat (ACQ) Pressure Treated, Spruce/Pine/Fir. Certify as specified in Section 106.03(b)3.

• Fasteners. Of the type indicated. Certify as specified in Section 106.03(b)3.

• Sealant. Silicone. Section 705.4(a)

875.3CONSTRUCTION—As shown on the Standard Drawings, as indicated, and as follows:

• Cement Concrete Structures. As specified in the applicable parts of Section 1001.3.

Fabricate trash rack(s) and galvanize as indicated. Excavate for concrete outlet structure as required. Place concrete foundations and walls monolithically, except if otherwise indicated. Construct new concrete outlet structure walls and bottoms to accommodate the dimensions of outlet pipes, weirs, and orifices. Form bottom of new concrete outlet structure with Class A Cement Concrete to channel the flow toward the outlet pipe as indicated. Attach trash racks to concrete outlet structure as indicated.

Set frames and top units in full mortar beds. Set pipes flush with the inside structure face. When constructing concrete outlet structure(s) in conjunction with existing pipes, provide for satisfactory connections, as specified for new construction of a similar type. Backfill excavated spaces around the structure with acceptable embankment material, as specified in Section 206.3(b)4, unless otherwise indicated. Satisfactorily dispose of unsuitable and surplus material. Coat all aluminum surfaces to be embedded in concrete with one coat of zinc chromate primer, or a coat of bituminous paint. Allow to dry completely before placing concrete. When concrete outlet structure is to be used for temporary sediment trap or sediment basin riser:

• Attach temporary orifice cover plates as indicated. Seal plate to concrete outlet structure such that it is leak tight.

• Do not install orifice trash racks until temporary orifice cover plates have been removed.

• Core/drill holes, of the diameter and spacing indicated, through concrete outlet structure and/or temporary orifice cover plate.

• When temporary orifice cover plate(s) are no longer required, satisfactorily remove plates and fasteners, and clean exterior face of structure. Satisfactorily dispose of materials. Seal all holes in structure that were installed for temporary purposes with non -shrinking mortar and/or silicone sealant. Attach permanent trash racks as indicated.

875.4MEASUREMENT AND PAYMENT—Each

TRAFFIC ACCOMMODATION AND CONTROL