211B BORROW AND STRUCTURE BACKFILL

211.01Description

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

MATERIALS

211.02Materials

Materials shall be in acco rdance with the following:

B Borrow ..................................................................... 904.06 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:

accordance with 917; or

list of Qualified Geotechnical Consultants for Gradation Control Testing.

For material excavated within the project limits, gradation control testing will be performed by the Department if the Contractor is directed to use the material as B borrow or as structure backfill.

The frequency of gradation control testing shall be one test per 2,000 t based on production samples into a stockpile or by over the scales measurement, with a minimum of two tests per contract, one in the beginning and one near the mid-point. 40

The sampling and testing of these materials shall be in accordance with applicable requirements of 904 for fine and coarse aggregates.

The Contractor shall notify the Engineer in writing of the plan to measure the material.

211.01

CONSTRUCTION REQUIREMENTS

211.03General 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.

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. Prior to placing the aggregate, a geotextile shall be installed in accordance with 616.11.

.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:

with 213.

accordance with 904.05, except No. 30, No. 4, and 2 in. nominal size aggregate shall not be used.

with 213.

( c ) T y p e 3 Structure backfill nominal size aggregates 1 in. or 1/2 in., or coarse aggregate No. 5, No. 8, No. 9, No. 11, or No. 12 in accordance with 904.05 shall be used.

AASHTO No. 57 aggregates that comply with 904 and with the coarse aggregate requirements in accordance with 904.05 may also be used.

If ACBF is used, it shall only be used in sizes that meet the size requirements for coarse aggregate No. 5 or No. 8, or AASHTO No. 57.

A Type A certification in accordance with 916 shall be provided for the additional structure backfill. The results of the following shall be shown on the certification.

Property Criteria Test Method pH (Note 1) 5 < pH < 10 AASHTO T 289 Organic Content (Note 2) 1% max. AASHTO T 267 Permeability, min. (Note 3) 30 ft/day AASHTO T 215 Notes:

cooled blast furnace slag, and each source of gravel.

each source. Sizes No. 5, No. 8, No. 9, and AASHTO No. 57 do not require a permeability test.

The gradation shall be performed on the material used in the permeability test. Testing for permeability shall be performed on the sample of the material compacted to 95% in accordance with AASHTO T 99, Method C or D. All of the tests listed above shall be performed a minimum of once every 12 months per source.

In addition to the criteria above, structure backfill for retaining wall systems containing metal components in contact with structure backfill shall also be in accordance with the following criteria:

Property Criteria Test Method Chlorides < 100 ppm AASHTO T 291 Sulfates < 200 ppm AASHTO T 290 Resistivity, min. 3, ȍ-cm AASHTO T 288 Internal friction angle, ij, min. 34° AASHTO T 236* or T 297* * under consolidated drained conditions

If the minimum resistivity exceeds 5, ȍ-cm, the requirement for the testing of chlorides and sulfates will be waived. The resistivity shall be tested at 100% saturation. All of the tests listed above shall be run a minimum of once every 12 months per source. The Department’s Division of Materials and Tests will evaluate the material from each source and determine the appropriate tests to be performed.

T HVWLQJIRUijVKDOOEHSHUIRUPHGXVLQJDVDPSOHRIWKHPDWHULDOFRPSDFWHGWR in accordance with AASHTO T 99, Method C or D. Testing for ijZLOl not be required when using coarse aggregate No. 5, No. 8, No. 9, or AASHTO No. 57.

Removable flowable backfill in accordance with 213.

( e ) T y p e 5 Non-removable flowable backfill in accordance with 213.

211.04Compaction

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

203.23except 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 with 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.

211.05Embankment 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

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.

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.

211.06B Borrow Around Bents

When specified, B borrow shall be placed around all bents falling 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.

211.07Blank

211.08Spandrel 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.

211.09Method 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, measurement will be made by the cubic yard at the loading point in truck beds which have been measured, stenciled, and approved.

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 computed by the average end area method. 211.06

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.

211.10Basis 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.

230

Structure backfill will be paid for at the contract unit price per cubic yard of the

type specified, provided the material comes 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 placed outside the 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 material for its own convenience. Material obtained

from within the excavation limits of the project and which the Contractor is directed260

to use as B borrow or structure backfill for other purposes including replacement of

undercut areas, support for a retaining wall system, 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.