SECTION 501 – SHEETING AND COFFERDAMS
501.01 Description
This Section describes the requirements for constructing and removing cofferdams and sheeting.
501.02 Materials
Provide materials as specified: Concrete ................................ ................................ ................................ ................................ ...................... 903.03 Structural Steel ................................ ................................ ................................ ................................ ............. 906.01 Steel Sheet Piles ................................ ................................ ................................ ................................ ........... 906.02 Bolts ................................ ................................ ................................ ................................ ............................ 908.01
501.03 Construction
501.03.01 Temporary Sheeting
A.Working Drawings. At least 30 days before beginning work, submit working drawings signed and sealed by a Professional Engineer for approval. Include the following:
1.Size, cross section, section modulus, and physical properties of the sheeting that will provide resistance to the maximum longitudinal bending moment for proper functioning.
2.Bracing design to protect workers, adjoining properties, and the public.
3.The combined stress calculations to determine the maximum effect of the principal stresses on the sheeting. Include a check for the principal stresses against the appropriate material yield point.
4.The effects of bending stresses in the longitudinal direction and the transverse direction.
5.The maximum forces that the sheeting is subjected to during construction operations.
6.The Contractor may use the Hencky -von Mises (Yield Distortion Energy) criterion to combine stresses and relate the principal stresses to a failure criterion (Material Yield Point).
7.Method for removing obstructions.
8.Method for addressing underground facilities and utilities that coincide with sheeting.
9.If required, dewatering plan, including method of dewatering and controlling sediment and contaminants from entering adjacent waterbodies, wetlands and environmentally sensitive areas. Do not use earthen berms as a method of dewatering.
B.Construction. Excavate and remove materials that ob struct the installation as specified in 202.03. Do not install within 200 feet of concrete that is being placed or has been placed within the previous 24 hours unless approved by the RE. Ensure that the sheeting has no gaps and is continuous for its entire length.
C.Dewatering. If required, dewater as specified in the approved dewatering plan. Continue dewatering operations until the temporary sheeting is removed or as directed by the RE.
D.Removal. Remove temporary sheeting when it is no longer required. Backfill voids left from temporary sheeting to provide uniform finish grades. Except for timber, the RE may approve leaving the temporary sheeting in place. When temporary sheeting is left in place, remove the upper portion to at least 3 feet below finish ground.
501.03.02 Permanent Sheeting
Construct permanent sheeting as shown on the Plans. Ensure that the sheeting has no gaps and is continuous for its entire length. At least 15 days before constructing sheeting, submit to the RE for approval a dewatering plan including method of dewatering and controlling sediment and contaminants from entering adjacent waterbodies, wetlands, and environmentally sensitive areas. Dewater according to the approved dewatering plan. Continue dewater ing operations until no longer required.
501.03.03 Temporary Cofferdam
A.Working Drawings. At least 30 days before beginning work, submit working drawings signed and sealed by a Professional Engineer for approval. Include the following:
1.Size, cross section, section modulus, and physical properties of the cofferdam that will provide the maximum longitudinal bending moment for proper functioning.
2.Bracing design to protect workers, adjoining properties, and the public.
3.The combined stress calculations to determine the maximum effect of the principal stresses on the cofferdam. Include a check for the principal stresses against the appropriate material yield point.
4.The effects of bending stresses in the longitudinal direction and the transverse direction.
5.The maximum forces that the cofferdam is subjected to during construction operations.
6.The Contractor may use the Hencky -Von Mises (Yield Distortion Energy) criterion to combine stresses and relate the principal stresses to a failure criterion (Material Yield Point).
7.A complete description of the proposed cofferdam.
8.Dewatering plan, including method of dewatering and con trolling sediment and contaminants from entering adjacent waterbodies, wetlands, and environmentally sensitive areas. Do not use earthen berms as a method of dewatering.
B.Construction. Construct cofferdam to ensure the stability of the excavation and to keep the excavation free of water. Construct the cofferdam with interior dimensions that allow clearance for the construction and inspection of forms and for the handling and pumping of water outside of the footi ng area. Extend the cofferdam below the bottom of the footings and brace cofferdams in all directions and ensure that they are maintained free of water until the subsequent work has been completed. The Contractor may only extend timber or bracing of a cofferdam into or through the proposed substructure with RE approval. Ensure that vertical structural members supported on rock are toed-in to ensure stability.
C.Dewatering. Continue dewatering operations until the temporary cofferdam is removed or as directed by the RE.
D.Removal. Remove temporary cofferdam when no longer required. Restore disturbed areas, including watercourse beds, to original conditions. The Contractor may re quest that the temporary cofferdam be left in place. If approved, the RE will designate the limits of the cofferdam to be left in place.
501.03.04 Permanent Cofferdam
A.Construction. Construct cofferdam to protect the foundation and the construction against damage and water. Ensure that vertical structural members supported on rock are toed-in sufficiently to provide stability against movement.
B.Placing Concrete Seal. When concrete seals are shown, submit a plan of operation to the RE for approval at least 30 days before placing concrete. Include the following in the plan:
1.Method of placing concrete.
2.Methods of controlling water and sediment intrusion.
3.Equipment models and quantity. Include backup equipment within the Project Limits at all times.
4.Size and description of crew.
5.Corrective action plan for equipment breakdown or cofferdam failure. Maintain still water at the point of deposit. Do not place concrete in running water. Ensure that plastic concrete does not come in contact with water outside of the confines of the cofferdam. Place con crete in a single continuous operation. To prevent segregation, place the concrete in a compact mass in its final position. Do not disturb the concrete after placement. Place concrete under water using one of the following methods:
1.Tremie Method. When using a tremie, ensure that the tube is at least 10 inches in diameter, and constructed in sections having flanged couplings fitted with gaskets. Support the tremie to allow free movement of the discharge end over the entire placement area and to allow its being lowered rapidly to choke off or retard the
Referenced in this section
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Source: Standard Specifications for Road and Bridge Construction, 2019 (rev. 2022-12-21) Edition. Pages 245–246 of 651. View official source ↗