232SECTION 211 – B BORROW AND STRUCTURE BACKFILL

211.01 Description

This work shall consist of backfilling excavated or displaced peat deposits; filling up to designated elevations of spaces excav ated for structures and not occupied by permanent work; constructing bridge approach embankment; and filling over structures and over arches between span drel walls, all with special material. MATERIALS

211.02 Materials

Materials shall be in acco rdance with the following: B Borrow ..................................................................... 904.06 Flowable Backfill ........................................................ 213 Geotextile .................................................................... 918.02 Structure Backfill ........................................................ 904.05 Aggregate for end bent backfill shall be No. 8 or No. 9 crushed stone or ACBF, class D or higher. 20 The Contractor has the option of either providing B borrow or structure backfill from an established CAPP source, or supplying the material from another source. The Contractor has the following options for supplying B borrow or structure backfill from a local site: (a) the establishment of a CAPP Producer Yard at the local site in accordance with 917; or

211.03 General Requirements 50

If B borrow or structure backfill is obtained from borrow areas, the locations, depths, drainage, and final finish shall be in accordance with 203. Unless otherwise specified, if excavated material complies with 211.02 and if B borrow or structure backfill is required for special filling, the excavated material shall be used as such. If there is a surplus of this material, such surplus shall be used in embankment. The provisions of 203.19 shall apply to placing this material at structures. All surplus in ex cess of the directed or sp ecified use on the right-of-way shall be disposed of in accordance with 201.03. 60 If fill or backfill as described in this specification is within embankment limits, and if it is not required that the entire fill or backfill be of B borrow and placed as such, then that portion above the free-water level shall be placed in accordance with applicable provisions of 203 and compacted to the required density. If borrow is required outside the specified limits of B borrow, material in accordance with the specifications for B borrow may be furnished at the contract unit price for borrow; however, the quantity of borrow measured for payment outside the limits of structure backfill will not exceed the theoretical quantity of B borrow furnished. 70 Unless otherwise specified, all spaces ex cavated for and not occupied by bridge abutments and piers, if within embankment limits, shall be backfilled to the original ground line with B borrow, and placed in accordance with 211.04. Where B borrow or structure backfill is required as backfill at culverts, retaining walls, sewers, manholes, catch basins, and other miscellaneous structures, it shall be compacted in accordance with 211.04. B borrow consisting of ACBF or GBF shall not be used within 2 ft of the free water level. Where specified, aggregate for end bent backfill shall be placed behind end bents and compacted in accordance with 211.04. Prio r to placing the aggregate, a geotextile shall be installed in accordance with 616.11.

211.03.1 Structure Backfill Types

The structure backfill type shall be as specified. Within each of th e following structure backfill types, the Contractor shall choose from the listed options for each type:

211.04 Compaction B borrow and structure backfill Type 1, Type 2, and Type 3 shall be compacted with mechanical tamps or vi brators in accordance with the applicable provisions of

203.23 except as otherwise set out herein. 150

Aggregate for end bent backfill and coarse aggregate used for structure backfill shall be deposited in layers not to exceed 12 in. loose measurement. Each layer shall be mechanically compacted w ith a compactor having a plate width of 17 in. or larger that delivers 3,000 to 9,000 lb per blow. Each lift shall be compacted with two passes of the compactor.

211.05 Embankment for Bridges When special filling is required, the embankment for bridges shall be constructed using B borrow within the specified limits shown on the plans. All embankment 160

construction details specifically set out in this specification for embankment for bridges shall be considered in accordance with the applicable requirements of 203. 211.05 236 At the time B borrow is being placed fo r approach embankment, a well compacted watertight dam shall be constructed in level lifts, the details of which are shown on the plans. Except as hereinafter specified for material to be used in constructing the enclosing dam, and for growing vegetation, and unless otherwise provided, the material for constructing bridge approach embankment shall be B borrow compacted by mechanical methods. 170 If approach embankment or shoulders are constructed of material not suitable for growing seed or sod, and if one or both of these is required, then such areas shall, unless otherwise specified, be covered with a layer of clay, loam, or other approved material. This layer shall be approximately 1 ft thick after being compacted into place.

211.06 B Borrow Around Bents When specified, B borrow shall be placed around all bents fall ing within the limits

of the approach grade as shown on the plans. Before placing, the surface of the ground on which it is to be placed shall be scarified or plowed as directed. The embankment slope shall be 2:1 on the sides and beneath the structure, and shall be 6:1 from the end 180 of the bridge down to the average ground line, or it may be required to complete the approaches back to the existing grade. An enclosing dam and provisions for growing vegetation shall be constructed in accordance with 211.05.

211.07 Blank

211.08 Spandrel Filling Unless otherwise specified, spandrel fills for arch structures shall be composed of

B borrow. The fill shall be carried up symmetrically in lifts from haunch to crown and simultaneously over all piers, abutments, and arch rings. Compaction shall be in 190 accordance with 211.04. 211.09 Method of Measurement B borrow, structure backfill Type 1, Type 2, or Type 3, and aggregate for end bent backfill will be measured by the cubic yard as computed from the neat line limits shown on the plans. If cubic yards are set out as the pay item for B borrow or structure backfill in the Schedule of Pay Items and if neat line limits are not specified for measurement of volume for the material, m easurement will be made by the cubic yard at the loading point in truck beds which have been measured, stenciled, and approved. 200 The B borrow may be weighed and converted to cubic yards by assuming the weight per cubic foot to be 90% of the maximum wet density in accordance with AASHTO T 99. The material may be cross-sectioned in its original position and again after excavation is complete, and the vo lume computed by the average end area method. If B borrow is used for backfill in areas where unsuitable material is present or peat excavation has been performed, unless otherwise directed, the B borrow will be cross-sectioned, and the volume will be co mputed by the average end area method. 211.06 237 210 Structure backfill Type 4 or Type 5 will be measured by the cubic yard as computed from the neat line limits shown on the plans. If neat line limits are not shown on the plans, the volume in cubic yards of flowable backfill furnished and placed as structure backfill Type 4 or Type 5 will be computed from the nominal volume of each batch and a count of the batches. Unused and wasted flowable backfill will be estimated and deducted. If the material is to be paid for by the ton, it shall be weighed in accordance with 109.01(b). 220 If the material comes from a wet source such as below water or a washing plant, and weighing is involved in the method of measurement, there shall be a 12 h drainage period prior to the weighing. Geotextile will be measured in accordance with 616.12.

211.10 Basis of Payment The accepted quantities of B borrow will be paid for at the contract unit price per cubic yard or per ton as specified, complete in place.

Structure backfill will be paid for at the contract unit price per cubic yard of the type specified, provided the material come s from outside the permanent right-of-way. B borrow material placed outside the neat lines will be paid for as borrow when such B borrow eliminates required borrow material. Otherwise, no payment will be made for backfill material pl aced outside th e neat lines. Aggregate for end bent backfill will be paid for at the contract unit price per cubic yard, based on the neat line limits shown on the plans. 240 Geotextile will be paid for in accordance with 616.13. If topsoil, loam, or other suitable material in accordance with 211.05 is used for expediting the growth of seed or sod, it will be paid for at the contract unit price per cubic yard for borrow, unless otherwise provided. Payment will be made under the following: Pay Item Pay Unit Symbol 250 Aggregate for End Bent Backfill ............................................... CYS B Borrow ................................................................................... CYS TON Structure Backfill, Type _____ ................................................. CYS 211.10 238 No payment will be made under this section for material obtained within the excavation limits of the project if the Contractor is directed to use the material as B borrow or structure backfill in a pipe trench, culvert, construction of an embankment or fill, or if the Contractor uses the materi al for its own convenience. Material obtained from within the excavation limits of the project and which the Contractor is directed 260 to use as B borrow or structure backfill for other purposes including replacement of undercut areas, support for a retaining wall sy stem, and end bent fill will be paid for at the contract unit price of $5.00 per cubic yard for B borrow/structure backfill handling. The cost of disposal of excavated material shall be included in the cost of the pay items in this section.