502REMOVAL OF EXISTING BRIDGE STRUCTURE

New Hampshire Department of Transportation Standard Specifications – 2016 Description

1.1This work shall consist of the removal and satisfactory disposal of the existing bridge structure as shown on the plans, except

such portions thereof as may be required or permitted to be left in place, or portions designated for salvage. Construction Requirements

3.1The Contractor shall dismantle the existing structure in any manner that will not cause damage to persons or prope rty.

Removal of those portions of the existing bridge over roadways, railroads, and waterways shall be accomplished with the least possible disruption of the normal traffic flow under the bridge. Special care and precautions, including protective structu res as required or ordered, shall be taken to ensure that no debris including slurry from sawcutting is allowed to fall on any roadway, railroad, or waterway. 3.1.1 Detailed plans showing the size, arrangement and quality of materials to be used in the rem oval of existing bridge structures and the construction of protective structures shall be submitted for documentation in accordance with 105.02. Plans shall show the proposed method(s) of removal, all required falsewor k, protective structures and equipment needed to accomplish the structure removal safely. 3.1.2 Lead-Bearing Paint.

contain hazardous concentrations of lead.

members, etc.) involving bridge components with LBP in conformance with the applicable worker protection provisions of OSHA 1926.62, Lead Exposure in Construction Final Rule; and LBP debris shall not be permitted to enter the environment in conformance with the environmental protection requirements of the NH Department of Environmental Services.

and environmental protection measures. The Contractor shall not commence with bridge removal work until receiving Department approval of the compliance plan.

LBP unless directed otherwise.

3.2If it is specified that the existing structure, or any portion thereof, is to be salvaged, it shall be dismantled and removed in

such a manner as to avoid damage to any member thereof. All structural steel me mbers shall be marked with paint indicating member size and grade of steel. 3.2.1 If it is specified that any part or parts of the existing structu re are to be salvaged for re- errection, all members shall be match-marked with paint before they are dismantled. All pins, bolts, nuts, loose plates, and the like shall be appropriately marked for identification and be placed in durable containers. Salvaged materials shall be stored in neat piles within the limits of the right- of-way adjacent to the work or loaded onto trucks as directed.

3.3All parts not designated for salvage on the plans or in the special provisions shall become the property of the Contractor and

shall be satisfactorily disposed of by the Contractor. Method of Measurement

4.1This item will be measured as a unit. When more than one unit is specified in the Contract, separate item numbers will appear

for each separate and complete unit.

4.2Limits of work shall be as established on the plans either by detail or by note. Unless otherwise shown, the horizontal limits

will not exceed the neat lines of the portion of the structure to be removed. 4.2.1 Unless otherwise shown on the plans, when the horizontal limits of bridge excavation, roadway excavation, or channel excavation fall within the spe cified removal limits of existing abutments, wingwalls or piers, the removal of the substructure material will be paid under the governing excavation item. Only portions of the existing bridge substructure which fall outside the horizontal limits of all other excavation items will be included as part of this item. Basis of Payment

5.1The accepted removal of existing bridge structure will be paid for at the Contract unit price.

5.1.1 Protective structures, if required or ordered, will be subsidiary. Pay item and unit: 502. Removal of Existing Bridge Structure Unit

New Hampshire Department of Transportation Standard Specifications – 2016

Description

This work shall consist of the design, construction, maintenance, and re moval of all cofferdams, caissons, cribs, sheeting,

embankments, channel diversion structures, pipes, and other similar work, including dewatering, required to allow the excavation for foundation units and to permit and protect the construction of bridge or other structural units. Materials

2.1All materials to be used in the construction of this work shall be subject to inspection and approval prior to their incorporation

in the structure.

2.2Sheeting specified to be left in place shall meet the requirements of 506.2.

Construction Requirements

General.

3.1.1 Cofferdams and water diversion structures shall be constructed so as to protect fresh concrete against damage from a sudden rising of the stream and to prevent damage to the footings and bridge units by erosion. 3.1.2 The Contractor shall submit drawings showing materials to be used, proposed method of construction, and other details left open to choice or not fully shown on the plans. When cofferdams are required or proposed, such information shall show the arrangement for flooding the cofferdam. Drawings shall be submitted for documentation in accordance with 105.02 .

Water Diversion Structures.

3.2.1 Temporary diversion channels, dikes, embankments and other similar structures shall be constructed in a way to minimize erosion and resulting water pollution. Appropriate measures of protection shall be incorporated into their construction. 3.2.2 Pipes, sluices, elbows, etc. that are used in the diversion of water shall be of sufficient size to carry the flow specified on the plans. 3.2.3 Temporary diversion channels, dikes and embankments shall be completely removed and restored to original or design grades as directed by the Engineer.

Cofferdams.

3.3.1 Cofferdams or cribs for foundation construction shall be carried to adequate depths and heights, shall be safely designed and constructed, and shall be as watertight as necessary for the proper performance of the work which must be done inside them. Interior dimensions shall be such as to give sufficient clearance for the construction and exterior inspection of forms and to permit pumping outside of the forms. In no case shall the sheeting be placed inside the neat lines shown for the concrete footing or seal. No construction material shall be left in cofferdams in such a way as to extend into the substructure masonry, without permission. 3.3.2 No excavation shall be made outside of cofferdams, nor shall the existing streambed adjacent to the structure be disturbed without the approval of the Engineer. When the Contractor is permitted to make excavation at the site of the structure before cofferdams are placed, all openings outside the cofferdams shall be backfilled with approved material to the elevations of the original ground or streambed after the cofferdams have been placed. 3.3.3 Cofferdams which are tilted or moved laterally during the process of sinking shall be righted, reset, or enlarged, so as to provide the necessary clearance, at the Contractor’s expense. 3.3.4 Unless otherwise provided, cofferdams including all bracing shall be removed by the Contractor after the completion of the substructure, with care being taken not to disturb the surrounding soil or injure the finished masonry. 3.3.5 Concrete foundation seals, when required or permitted, shall be constructed as provided in Section 520. 3.3.6 Cofferdams with sheeting left in place. 3.3.6.1 When called for on the plans, cofferdam sheeting shall be cut off at the top of the foundation seal or footing or at the specified elevation. The length of sheeting left in place below the specified cut off elevation will be the minimum embedment length shown on the plans or the length required on the approved cofferdam design drawings. 3.3.6.2 Anchorage between the cofferdam sheeting and concrete foundation, if required, will be detailed on the plans.

3.4Dewatering.

3.4.1 Control of water within cofferda ms shall be in such a manner as to prevent disturbance of the bearing soil, or fresh concrete, or segregation of backfill material. Pumping areas shall be properly filtered to prevent pumping of fines.