298 SECTION 626
626.01 Description
This work consists of designing, constructing, dewatering, maintaining, removing, and backfilling cofferdams.
626.02 Equipment
Reserved.
626.03 Materials
Reserved.
626.04 Construction Requirements
A.General. Design and construct cofferdams to be watertight as necessary to perform the work. Provide sufficient clearance in the cofferdam for: − Construction; − Inspection of the exterior forms; and − Placement of pumping equipment. If foundation seal concrete is necessary, it must be placed as specified in Section 602.04
C.1.b(2), “Foundation Seal Concrete” .
B.Excavation. Perform cofferdam excavation as specified in Section 210, “Structural and Channel Excavation, Foundation Fill and Preparation” .
C.Removal of Cofferdams. Remove cofferdams when no longer needed. Do not excavate below the natural channel bottom outside the cofferdam to facilitate rem oval. After removing the cofferdam, place backfill material as specified i n Section 210.04 B.2, “Ordinary Backfill” . Fill the excavated area to the natural channel bottom.
626.05 Method of Measurement
The Engineer will measure as specified in Section 109.01, “Measurement of Quantities” and as follows: If multiple cofferdams are constructed to protect a single portion of the work, the Engineer will measure it as a single cofferdam. Excavation for cofferdam s will be measured as specified in Section 210.05, “Method of Measurement” . Excavation inside the cofferdam and outside the limits defined in the plans will not be measured. 299 626.06 BASIS OF PAYMENT Pay Item Pay Unit Cofferdam Each Pier Cofferdam Each The Department will pay 50 percent of the contract unit price when the cofferdam is installed. The Department will pay 50 percent of the contract unit price when the cofferdam is removed. Excavation for cofferdams will be paid for as specified in Section 210.06, “Basis of Payment” . Include excavation inside the cofferdam and outside the excavation limits defined in the plans in the contract unit price for cofferdam items. Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified. Section 650 300 SECTION 650 OVERLAY OF CONCRETE BRIDGE DECKS
650.01 Description
This work consists of removing and replacing unsound concrete and/ or chloride contaminated concrete and resurfacing a bridge deck.
650.02 Equipment
A.General. Equipment Section Bridge Deck Overlays Finishing Equipment 155.07 D Sawing 155.09 Grinding 155.11 Concrete Buggy 155.12 Fogger 156.02 Milling Machine 156.03
B.Sandblasting Equipment. Use sandblasting equipment that removes rust scale, oil, and concrete lattice from the surface of the bridge deck and uncoated reinforcing bars . Do not use equipment that employs the wet sandblasting method. Equip airlines with filters that remove all oil from the air used by the sandblaster.
C.Pneumatic Hammers. Use hammers that ar e no larger than the nominal 30 pound class. Use chipping hammers no larger than the nominal 15 pound class to remove concrete around or beneath reinforcing bars. Pointed bits for pneumatic hammers may only be used when performing Class 4 removals.
D.Hand Tools. Provide hand tools, such as hammers and chisels, for the removal of final particles of unsound concrete or to achieve the required depth.
E.Hydrodemolition Equipment. Use hydrodemolition equipment with a water filter and pumping unit that operates in conjunction with a remotely controlled robotic water jet unit. Use equipment that produces high velocity water streams capable of removing concrete to the specified depth and is capable of removing rust and concrete from reinforcing bars. Use potable water. Calibrate the equipment by adjusting water pressure, robot speed, and jet oscillation speed to achieve the required depth of removal.
F.Placing and Finishing Equipment. Placing and finishing equipment includes hand tools used for placing and brushing mixed mortar and for distributing concrete to a depth sufficient for the concrete to be struck off with a screed.
Source: North Dakota Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 333–334 of 550.