851SECTION 733 – STEEL BIN-TYPE RETAINING WALL

733.01 Description

This work shall consist of furnishing materials and placement of steel bin-type retaining walls in accordance with 105.03. MATERIALS

733.02 Materials

Materials shall be in acco rdance with the following: 10 Fasteners ...................................................................... 910.02(g)1 Steel Bin-Type Retaining Wall Units .......................... 910.08 Structure Backfill ........................................................ 211.03.1, 904.05 Backfill material used in the bin-wall sections shall be Type 3 structure backfill in accordance with 211. CONSTRUCTION REQUIREMENTS

733.03 General

All units shall be fabricated such that units of the same nominal size shall be fully interchangeable. Drilling, punching, or drifting to correct defects in manufacture will not be allowed. Each unit with unauthorized holes shall be replaced. The ends of all stringers and spacers shall be bolted to corner columns by means of connecting channels. The proper curvature for the face of a wall constructed on a curve shall be obtained using shorter stringers in the front or rear panels of retaining walls as shown on the plans or as otherwise directed. 30 The wall height and depth may be varied. Two or more retaining wall designs may be incorporated in the same wall using st andard split columns to make the connection on the step back. 733.04 Foundation Preparation The foundation for the structure shall be graded level or as shown on the plans. Prior to wall construction, the foundation, if not in rock, shall be compacted in accordance with 203. The base of the wa ll excavation shall be proofrolled with a vibratory roller weighing not less than 10 t, or with other approved compacting 40 equipment. If unsuitable foundation material is encountered, it shall be removed and replaced with B borrow in accordance with 211.02 and compacted in accordance with 211.04.

733.05 Retaining Wall Excavation Retaining wall excavation shall be in accordance with 731.08. 733.05

733.06 Backfill Placement

The fill material for the interior of the bin and behind the wall shall be structure backfill placed in layers not to exceed 6 in. in thickness. Backfilling behind the wall 50 shall progress with the filling of the bins and shall not be carried ahead of the interior bins. Existing slopes, which are shaped to cause a wedge action in the backfill, shall be benched before backfilling. The moisture content of the backfill material prior to and during compaction shall be uniformly distributed thro ughout each layer. Backfill material shall have placement moisture content between optimum and -3 percentage points of the optimum moisture content. Backfill material with placement moisture content exceeding the optimum moisture content shall be removed and reworked until the moisture content is uniformly acceptable through the entire lift. 60 Compaction within 3 ft of the back face of the bins shall be achieved by means of a minimum of three passes with a lightwe ight mechanical tamp er, roller, or an alternative vibratory system. Backfill placement shall otherwise be in accordance with 731.11.

733.07 Method of Measurement

The measurement of steel bin walls will be based on the square foot of area contained within the neat line limits of the wall envelope shown on the plans and not 70 that of the wall system supplier. Common excavation will be measured in accordance with 203.27. Structure backfill will be measured in accordance with 211.09. Unsuitable foundation materials, if found, will be measured in accordance with

211.09 733.08 Basis of Payment

This work will be paid for at the contract unit price per square foot for binwall, steel. Common excavation will be paid for in accordance with 203.28. Structure backfill will be paid for in accordance with 211.10 . Unsuitable foundation materials will be paid for in accordance with 211.10. 80 Payment will be made under: Pay Item Pay Unit Symbol Binwall, Steel ............................................................................ SFT The cost of furnishing, handling, and installing the steel units, including all materials, bolts, and appurtenances; neces sary excavation and structure backfill testing; and all labor, equipment, all neces sary incidentals, or replacement of steel 90 units with unauthorized holes, or those damaged and replaced during construction shall be included in the cost of the pay item. 733.06