7-6 Section 704. Steel Sheet Piling and Cofferdams
704.01. Description This work consists of the following:
A.Providing and driving permanent steel sheet piling;
B.Designing, providing, installing, maintaining, and removing temporary steel sheet piling, bracing, tie backs, walers, and related material or cutting off temporary steel sheet piling left in place; and
C.Designing, providing, installing, maintaining, and removing cofferdams , sheet piling, bracing, tie backs, walers, and related material or cutting off cofferdams left in place. 704.02. Materials Provide material in accordance with the following sections : Geosynthetics ....................................................................................... 910 Steel Sheet Piling .................................................................................. 906 Provide new or used continuous interlock -type steel sheet piling, including connections and corner pieces . Used steel sheet piling must be in good condition, and its use must be approved by the Engineer . Provide temporary steel sheet piling and cofferdams with a nominal section modulus of at least 18.1 cubic inches per foot of wall when installed adjacent to traffic or when supporting traffic loads . Provide the permanent steel sheet piling section modulus shown on the plans. For permanent installations, provide structural steel, high-strength steel bolts, nuts, and washers in accordance with section 906. The Contractor may provide cold-rolled sheeting for applications specified in this section. 704.03. Construction
A.Design . Design steel sheet piling and cofferdams in accordance with the AASHTO Standard Specifications for Highway Bridges , 17th edition, and the contract. Include the following information, as applicable, in the design and on working drawings :
1.Sheet piling section modulus and embedment depth;
2.Design criteria for bracing and bracing sections, connection s, tie-back details, and deadman sections; MDOT Standard Specifications for Construction Section 704
7-7 3. Assumptions and references for the design calculations;
4.Any loads for construction equipment, construction material s, traffic loading, and any unbalanced hydrostatic pressure loading; and
5.Profile views and plan views with cross sections . Submit an electronic file copy of the proposed design, supporting calculations , and working drawings for steel sheet piling and coffe rdams to the Engineer for review not less than 1 4 calendar days before beginning work . Document each stage of construction on the working drawings. At cofferdam and steel sheet piling locations where the combined depth of retained water and/or soil is 6 feet or greater , the working drawings and design calculations must be prepared and sealed by a Professional Engineer licensed in the State of Michigan. The Professional Engineer must be competent in geotechnical and structural engineering. For cofferdams wit h a tremie seal, the minimum top of cofferdam elevation must be the design water surface elevation for the tremie seal . Cofferdam construction must ensure no free- flowing water into the cofferdam. Do not begin installation until after the Engineer approves the design and working drawings . Prepare and submit working drawings and design calculations in accordance with subsection 104.02. Provide a copy of any steel sheet piling or cofferdam design and working drawings at the job site as required by MIOSHA Cons truction Safety Standards .
B.Driving Steel Sheet Piling. Drive, brace, and cut off steel sheet piling in accordance with the Contractor ’s temporary sheet piling and cofferdam design and working drawings and the contract. Drop hammers may be used. Unless otherwise shown on the plans, vibratory hammers may be used. Cut off temporary steel sheet piling, left in place, to the elevation shown on the plans . Do not pull up or redrive temporary steel sheet piling, left in place, to match the cutoff elevati on required, unless otherwise shown on the plans or approved by the Engineer . Coordinate steel sheet piling and cofferdams with the construction staging required by the contract. After casting adjoining concrete, do not drive steel sheet pilings to a great er depth. To lower the top of sheet piling after placing adjoining concrete, remove by cutting. MDOT Standard Specifications for Construction Section 704
7-8 Do not install or remove steel sheet piling within 25 feet of newly placed
concrete until the concrete attains at least 70% of the required minimum 28-day flexural or compressive strength.
C.Cofferdams . Construct partial or total enclosure cofferdams to allow construction of substructures, above the tremie seal or subfooting, in the dry without damaging the work . The Engineer may approve alternat ive methods instead of cofferdams . The Engineer will consider approval after receiving applicable Michigan Department of Environment, Great Lakes, and Energy or other permits for the alternat ive method. Construct cofferdams with interior clearance for constructing forms and inspecting form exteriors and to allow pumping outside the forms . Construct cofferdams to protect the work from damage from high water and prevent damage to the foundation by er osion. Align or enlarge cofferdams that tilt or move laterally to provide requi red clearance. Do not brace cofferdams to substructure forms . Bracing that extends into or remains in the finished concrete is not permitted. If the plans call for a tremie seal, maintain the water level inside the cofferdam equal to the water level outside the cofferdam until the tremie seal is placed and attains the required minimum strength in accordance with subsection 706.03.H.3. If dewatering, pump from a sump located outside the forms . If the plans do not call for a tremie seal, discharge water pumped from a cofferdam into a geotextile filter bag. After placing tremie seal and initially dewatering into a geotextile filter bag, silt -free and sediment -free water may be pumped directly into the watercourse if approved by the Engineer. Remove coffer dams without disturbing or marring finished concrete. Cut off the cofferdams, left in place, to the elevation shown on the plans . Do not pull up or redrive cofferdam sheeting to match the cutoff elevation unless otherwise shown on the plans or approved by the Engineer.
D.Field Welding. Perform field welding in accordance with the AWS D1.1 , Structural Welding Code –Steel and as modified herein. Welding personnel such as welders, welding operators, and tack welders must be qualified in accordance with AWS D1.1. Testing must be in accordance with MDOT ’s Welder Certification Program . The period of effectiveness for field welding personnel endorsed through MDOT ’s Welder Certification Program is 2 years unless welding personnel are not engaged in a welding process for at least 6 months or a specific reason exists to question the welder personnel ’s ability . The Engineer may require a confirming performance test during the progress of the work. MDOT Standard Specifications for Construction Section 704
7-9 704.04. Measurement and Payment
Pay Item Pay Unit Steel Sheet Piling, Permanent ....................................................... Square Foot Steel Sheet Piling, Temp ............................................................... Square Foot Steel Sheet Piling, Temp, Left in Place .......................................... Square Foot Cofferdams (Structure Identification) ............................................... Lump Sum Cofferdams, Left in Place (Structure Identification) .......................... Lump Sum All cost s associated with shop or field welder endorsement to MDOT ’s Welder Qualification Program testing including, but not limited to, providing the specimen test plates, completing performance testing, and submittal of qualification specimen will be at the Contractor ’s expense.
A.Steel Sheet Piling
1.Steel Sheet Piling Permanent . The Engineer will calculate quantities of Steel Sheet Piling , Permanent based on the lines and lengths below cutoff, shown on the plans or authorized by the Engineer.
2.Steel Sheet Piling, Temp and Steel Sheet Piling, Temp, Left in Place The Engineer will calculate quantities of Steel Sheet Piling, Temp and Steel She et Piling, Temp, Left in Place based on the area of earth retention. The Engineer will calculate the vertical dimension of the area based on the difference in ground elevations at the sheeting line or the planned foundation excavation limits at the sheeting line, whichever is less. Unless otherwise shown on the plans, the Engineer will calculate the lateral limits based on the design specified in subsection 704.03.A. If retaining earth on both sides of the same steel sheet piling during different constructi on stages, the Engineer will calculate the quantity based on the stage requiring the largest area of earth retention, not the sum of the areas of earth retention for each stage. The Engineer will take horizontal measurements along the sheet piling alignment without allowance for the structural shapes of the separate sections.
a.Steel Sheet Piling, Temp . The unit price for Steel Sheet Piling, Temp includes designing, providing, installing, maintaining, and removing the sheet piling, bracing, tie backs, walers, deadm en, related material, and equipment required to maintain support of the sheeting and adjacent embankment.
b.Steel Sheet Piling, Temp, Left in Place . The unit price for Steel Sheet Piling, Temp, Left in Place includes designing, providing, MDOT Standard Specifications for Construction Section 704
7-10 installing, m aintaining, and cutting off the sheet piling, bracing, tie
backs, deadm en, walers, related material, and equipment required to maintain support of the sheeting and adjacent embankment.
B.Cofferdams . The Engineer will measure, and the Department will pay for , filter bags as specified in subsection 208.04.
1.Cofferdams . If the contract includes a separate pay item for Cofferdams , the Engineer will group and measure cofferdams for the structure as a unit . The unit price for Cofferdams, of the type required, includes designing, providing, installing, maintaining, dewatering, and removing sheet piling, bracing, tie backs, walers, deadm en, and related material.
2.Cofferdams, Left in Place. If the contract includes a separate pay item for Co fferdams, Left in Place, the Engineer will group and measure cofferdams specified as left in place for the structure as a unit. The unit price for Cofferdams, Left in Place includes designing, providing, installing, maintaining, dewatering , and cutting off of sheet piling, bracing, tie backs, walers, deadm en, and related material. If the contract does not include a pay item for Cofferdams or Cofferdams, Left in Place, the cost of constructing a cofferdam for structures not crossing streams is included in th e unit prices for other items of work; for structures crossing streams or encroaching on water courses, the cost of constructing a cofferdam will be paid for as extra work. If the Engineer authorizes an alternat ive method to a sheet pile cofferdam, the Dep artment will pay for the alternat ive method at the unit price for Cofferdams or Cofferdams, Left in Place.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 370–374 of 1,146.