SECTION 206 — EMBANKMENT
— This work is the construction of embankments and backfills.
206.2 MATERIAL —
(a) Embankment Material.
Obtain material for embankment construction from the various classes of excavation on the project, including Common Borrow Excavation, Foreign Borrow Excavation, and Selected Borrow Excavation, all meeting the following requirements:
Material of maximum size that can be readily placed in loose 8-inch layers, except as specified, and classified as follows:
Includes earth material with the following physical characteristics
Gradation — More than 35% passing No. 200 Sieve.
Minimum Dry Weight Density — 95 pounds per cubic foot, determined in accordance with PTM No. 106, Method B.
Maximum Liquid Limit — 65, determined in accordance with AASHTO-T89.
Plasticity Index — Not less than Liquid Limit minus 30, determined in accordance with AASHTO-T90 for soils with liquid limits of 41 to 65.
1.b Granular Material.
Includes natural or synthetic mineral aggregates having 35% or less passing the No. 200 sieve.
1.c Shale. Includes
rock-like material formed by natural consolidation of mud, clay, silt, and fine sand; usually thinly laminated, comparatively soft, and easily split.
Includes natural material that cannot be excavated without blasting or using rippers; also boulders and detached stones of a size that cannot be readily placed and compacted in loose 8-inch layers and having insufficient soil to fill the voids in each layer.
1.e Random Material.
Includes any accepted combination of the above classifications and may include concrete, brick, stone, or masonry units from demolition.
2. Suitable Material.
Reasonably free of organic matter, coal or coal blossom, or other objectionable matter. Wet, dry, or frozen material may be suitable when dried, wetted, or thawed, respectively.
Suitable material, including wet or frozen material, may be wasted only with written authorization and is subject to replacement in equivalent volume.
206.3 CONSTRUCTION —
Prepare the embankment foundation area, as specified in Section 201.
Backfill existing depressions in embankment areas, such as gullies, old stream channels, stump holes, and areas of undercutting and topsoil or pavement removal, all to adjacent ground elevation.
Plow or scarify embankment foundation areas, where undercutting is not directed, to a depth of at least 8 inches and compact to the specified density. However, in wet areas or where field conditions warrant, the Engineer may waive this requirement.
Break existing pavements, more than 3 feet below the finished grade, as follows:
break bituminous pavements to a maximum size of 1 sq. ft. and recompact;
break concrete pavements to a maximum size of 1 sq. yd.;
scarify bituminous, surface-treated roadways to a depth of 6 inches and recompact.
When constructing embankment on an existing slope, bench the slope to the width and depth indicated, or as directed.
Where required for installation of transverse drainage, construct embankment as shown on the Standard Drawings.
(b) Placement and Compaction.
Except as specified in Section 206.3(b)2., place embankment material, other than rock, in uniform horizontal layers of not more than a loose 8-inch depth for the full width, unless otherwise directed. Material may be end-dumped in water to the elevation necessary to establish a satisfactory working platform if granular material or rock is used.
Compact each layer for its full width to not less than 97% of the determined dry weight density; except, compact material in the top 3 feet of embankment to not less than 100% of the determined dry weight density. In-place density or compaction will be determined in accordance with PTM No. 112 or PTM No. 402. At the time of compaction, maintain the soil moisture content within plus or minus 2 percentage points of the optimum moisture content for that material. When the material is too coarse (more than 20% retained on the 3/4-inch sieve) to satisfactorily use these methods, compaction will be determined on the basis of nonmovement of the material, under compaction equipment specified in Section 108.05(c)3.a, 3.b, 3.e, 3.h, or 4.
Place rock, shale, and random material with coarser material in the outside and place finer material in the center of the embankment to produce a gradual transition in size. Using equipment, break the large pieces until most voids are filled.
Shape the top layer of the compacted embankment to drain during construction.
2. Wet and/or Unstable Foundation Areas.
Where the embankment foundation is in water or swamp areas or is saturated or unstable, construct embankment with granular material or rock to the indicated elevation, or as directed.
Construct embankment on saturated or unstable material, as indicated. Place 3 feet of select granular material meeting the requirements of Section 703.3, then place rock embankment.
3. Existing Embankment.
When an existing embankment requires additional material to bring it to the required elevation, thoroughly scarify the embankment top before placing the additional material.
Areas. In areas inaccessible to compaction equipment, place embankment material in uniform loose layers not exceeding 4 inches in depth; compact to required density by means of mechanical tampers.
5. Structure Areas.
As specified in Sections 1001.3(q)2.b and (t), and construct embankment behind bridge abutments and adjacent to structures under embankment with Selected Borrow Excavation, as shown on the Standard Drawings. Do not place rock where piles are to be driven.
Do not place rock in embankment without acceptance of the planned excavation and embankment operations.
When used to form the base of embankment, place rock the full cross section width. Place rock on embankment side slopes, where indicated. When permitted, excess rock disposed of on side slopes need not be compacted.
Place rock in uniform loose layers not exceeding in depth the approximate average size of the larger rock, but limited to a maximum depth of 36 inches. Reduce oversize rock in size until it can be readily incorporated in a 36-inch layer. Do not dump rock in final position, unless specified, but distribute by blading or dozing; keep voids, pockets, and bridging to a minimum. Place rock embankment so larger pieces are evenly distributed and voids are filled as completely as possible. Limit the top layer of rock embankment to a maximum depth of 12 inches, and fill voids with smaller pieces, spalls, or granular material.
Before rock is placed on other compacted embankment material, slope the top of the embankment from centerline to the sides, at a rate of approximately 1 inch to the foot, and compact the embankment top. Do not bench embankment for placement of rock embankment or rock slopes, unless directed or permitted.
When rock and other embankment material are placed at the same time, place the other material sufficiently above rock layers to allow for compaction.
7. Frozen Material.
Thaw frozen material before placing in embankment. Do not place embankment material on any material frozen to a depth of 3 inches or more. Remove frozen material, if the embankment top freezes to a depth of 3 inches or more, before placing additional material.
8. Wet Material.
Dry material to at least the optimum moisture content before compacting in embankment. Do not place material on embankment made unstable by excessive moisture.
9. Dry Material.
Moisten material to the optimum moisture content before compacting in embankment.
Assume responsibility for the stability of embankment. Replace embankment which, in the judgment of the Engineer, has been damaged or displaced, due to the following: carelessness or negligence, natural causes such as storms and floods, shrinkage of embankment material, and for all other reasons not attributable to other than movement of the natural ground upon which embankment is placed.
In addition, dry, reshape, and recompact material if the movement of heavy construction equipment on embankments causes movement, rutting, or displacement of the material under compaction or hauling equipment. The material will again be tested for density and moisture requirements.
206.4 MEASUREMENT AND PAYMENT —
When measurement is required, embankment will be measured in its final position, as specified in Section 203.4(a)2., by the cubic yard.
Embankment construction will be considered incidental to excavation or borrow excavation and will not be paid for separately.
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