100	SCOPE OF WORK: Work at this site consists of extending a quadruple 10' x 8' reinforced concrete box culvert 23'-0" on both ends.

202	REMOVAL OF CONCRETE: Remove portions of existing culvert end where extension is to be attached. Remove 1'-6" of existing concrete to expose the existing reinforcing steel at the parapet, roof, and outside walls at the vertical junction with the wing. Remove existing wing walls in entirety. Cut rebar protruding from the floor under the wing walls flush with the top surface of the floor. Leave existing floor and cutoff walls in place.

602	CLASS AE-3 CONCRETE: The strength requirements of Section 802.01 A.2 “Class AE and AAE Mixes” are revised to develop a design compressive strength of 3,000 psi (AE-3) and 4,000 psi (AAE-3) at 28 days.

Cast the following elements of each section in one continuous run:

Floor slab and wing footings

Each intermediate wall up to the bottom of fillets

Each sidewall up to the bottom of fillets with its

adjacent wings complete to the top

Roof slab and parapets

Allow the concrete in the walls to set at least two hours before the roof slab is poured.

If the existing wall and roof thicknesses are different than the new thicknesses, align the inner surfaces and taper the exterior surfaces in the first 1'-6" of the barrel.

602	CURING CONCRETE: Wet cure all concrete surfaces not covered by forms. Cover the concrete with a double thickness of burlap. Maintain surface moisture between the final finish and placement of burlap by periodic applications of a light fog spray of water. Keep the burlap continuously moist until the end of the curing period.

602	WEATHER LIMITATIONS: All requests in accordance with 602.04 C.4 “Weather Limitations” require approval from the NDDOT Bridge Division.

612	REINFORCING STEEL: Place bolsters and bar supports for the roof steel at a maximum of 4 foot spacing.

Dimensions of bent bars are given out to out.