2107.01 DESCRIPTION.
Embankment construction shall consist of the preparation of the site, and placement and compaction of excavated materials to the required elevation and cross section as shown in the contract documents and in accordance with the following requirement:

If the type of compaction is not specified, Type A compaction will be required.

2107.02 EQUIPMENT.
The equipment shall meet requirements of Section 2001 and the following:

A. Compaction Equipment.
When compaction with moisture and density control is not specified, equipment shall meet requirements of Article 2001.05, A. Other types of compacting equipment may be used as provided in Article 2107.07.

For compaction of sand or other granular material, the Contractor shall use a self propelled, pneumatic roller meeting the requirements of Article 2001.05, C, or a self propelled vibratory roller meeting the requirements of Article 2001.05, F.

When special backfill is required, it shall be compacted with equipment meeting the requirements of Article 2001.05, Paragraphs B, C, D, F, or other types of compacting equipment as provided in Article 2107.07.

When compaction with moisture and density control is specified, any type of equipment may be used for compaction which will produce the desired results.

B. Equipment for Applying Water.
Article 2001.09 shall apply.

2107.03 PREPARATION OF THE SITE.
Where the height of proposed embankment at the center line is 5 feet (1.5 m) or less, all sod, after thorough disking, shall be removed from the area and placed on the area to be occupied by the outer portion of the embankment as provided in Article 2107.04.

Whenever an embankment is placed on or against an existing slope which is generally steeper than 3 horizontal to 1 vertical and is more than 10 feet (3 m) high, the slope shall be cut into steps as the construction of the new embankment progresses. These steps shall assure that all sod or other potential sliding surfaces are removed. Each step or series of steps shall be cut to approximate horizontal planes which have vertical slope cut dimensions of not less than 3 feet (1 m).

2107.04 DEPOSITING EMBANKMENT MATERIAL.
Except for rock fills and granular blankets, embankments shall be deposited in horizontal layers not over 8 inches (200 mm) in loose thickness. The outer portion of an embankment shall be kept lower than its center, and wherever construction is to be suspended for a period during which rain is likely to occur, the surface shall be smoothed to produce a surface sufficiently smooth and compact to shed water. Soils containing quantities of roots, sod, or other vegetable matter shall be deposited outside of the shoulder line and within the outer 3 feet (1 m) of the embankment. Tree stumps and other large woody objects shall not be deposited in embankments. Wherever it is practical to do so without an increase in average haul, layers of drier soil shall be alternated with layers of wetter soil. Embankments shall not be constructed on frozen ground, and frozen material shall not be used in construction of embankments.

Where Type A or Type B compaction operations are to be used, the following shall apply:

1. When the width at the attained height is 30 feet (10 m) or more, the Contractor shall divide the area upon which the layer is to be placed into separate and distinct dump areas having widths not less than 15 feet (5 m). If hauling equipment is operated within a dump area, the area shall be covered with at least one passage of a tandem axle disk or two passages with a single axle disk, prior to compaction.

2. Hauling equipment shall be kept off dump areas of embankments 36 feet (11 m) or more in width during compaction operations. Within 36 feet (11 m) of a bridge or other limiting structure or where the width of the embankment is less than 36 feet (11 m) at the attained height, empty hauling units may travel on the dump area during compaction operations as necessary to pass loaded hauling units. If the design width of embankment is less than 30 feet (10 m) at the attained height, hauling units will be allowed to travel through areas where compaction operations are in progress. When any hauling equipment is allowed to pass through compaction operations, water, disking, and compacting equipment shall not be required to deviate from their intended paths.

3. The material shall be deposited over the dump area as a separate and distinct operation. If the material, as deposited, contains an average of more than 1 lump per square yard (square meter) large enough to have at least one dimension greater than 12 inches (0.3 m), the area shall be covered by at least one passage of a tandem axle disk or two passages of a single axle disk. The disk shall be designed and operated to cut and stir to the full depth of the layer.

After depositing and disking, if required, the material shall be smoothed to a uniform depth by means of a suitable motor patrol, bulldozer, or self propelled sheepsfoot type roller with a blade attachment. In addition to the initial smoothing operation, this smoothing and leveling of the lift shall continue during compaction, as necessary, to provide a surface area free from ruts and other objectionable irregularities. The self propelled, sheepsfoot type roller with blade attachment may be used under the following conditions:

Leveling must be done according to the prescribed rolling pattern. Compaction shall be the major function of this unit. Spinning of the power drums shall be prevented. When, in the opinion of the Engineer, the unit cannot satisfactorily accomplish both leveling and rolling, a separate dozer or motor patrol shall be used for the leveling operation prior to initiation of compaction.

2107.05 TYPE A COMPACTION.
Type A compaction refers to compaction requiring a minimum of one rolling per inch (25 mm) depth of each lift, and it is further required that the roller continue operation until it is supported on its feet, or the equivalent.

After the surface of the layer has been smoothed and before material for the next layer is deposited upon it, the layer shall be compacted with not less than one passage of the sheepsfoot type roller per inch (25 mm) of loose thickness of the layer and until the roller is supported entirely on its feet. The roller will be considered to be supported entirely on its feet when the tamping feet penetrate not more than 3 inches (75 mm) into an 8 inch (200 mm) lift or layer being compacted.

It will be the Contractor's prerogative to determine if moisture content of the material is excessive or suitable for satisfactory compaction. The Contractor may elect to start rolling operations immediately after the smoothing operation, or may elect to delay rolling operations, and instead, aerate the material in preparation for rolling. Aeration and compaction operations shall proceed in an orderly fashion without unreasonable and unnecessary delay. Rolling operations made prior to any aeration operations for a lift will not be counted as any of the required coverages.

Should the material be dry to the extent that it is likely to fail to be satisfactorily compacted by rolling, the Contractor may moisten the material, or the Engineer may order the material to be moistened uniformly, before it is compacted. Authorization may be given for the use of water in the final finishing of the roadbed.

Compensation will not be allowed for delays occasioned by the ordering of moistening or by drying.

The Contractor may request approval of other methods and equipment according to Article 2107.07.

2107.06 TYPE B COMPACTION.
Type B compaction refers to compaction requiring a specified number of diskings and roller coverages, or the equivalent.

After the surface of the layer has been smoothed and before the next layer is deposited upon it, the layer shall be compacted or disked and compacted.

If the soil in the layer is in a condition that it will be compacted by one passage of the roller per inch (25 mm) of loose thickness of the layer so that the entire weight (mass) of the roller is supported on its feet, the layer shall be so compacted.

A roller will be considered to be supported entirely on its feet when the feet penetrate not more than 3 inches (75 mm) into an 8 inch (200 mm) lift or 33% of the depth of the layer being placed.

If, at the time it is deposited, the soil in the layer is wet to the extent that it will not be compacted to a degree that the entire weight (mass) of the roller is supported on its feet, the Engineer may require not more than one disking per 2 inches (50 mm) of loose thickness of the layer, in addition to the disking required in the smoothing operation. A disking shall consist of a complete coverage of the layer with either a tandem axle disk or a single axle disk. The disk shall be designed and operated to cut and stir to the full depth of the layer. The Engineer may require an interval not longer than 2 hours between successive diskings. After the disking has been completed, the layer shall be compacted by one passage of a sheepsfoot type roller per inch (25 mm) of loose thickness of the layer.

The manipulation and compaction specified above shall be incidental to Class 10 or Class 13 excavation. The Engineer may require additional manipulation and compaction as extra work. If the soil is so dry that it will fail to be satisfactorily compacted by rolling, the Engineer may require the Contractor to moisten the material uniformly before it is compacted.

Compensation will not be allowed for delays caused by the ordering of moistening or by disking.

The Contractor may substitute Type A compaction at no additional cost to the Contracting Authority where Type B compaction is specified, by written notification to the Engineer, or the Contractor may request approval of other methods and equipment according to Article 2107.07.

2107.07 COMPACTION BY OTHER METHODS AND EQUIPMENT.
Other methods of compaction may be used provided it is demonstrated that suitable compaction of a variety of soil types and moistures normally encountered will be obtained. Compaction will be considered suitable if the resulting density, with adequate moisture, is reasonably uniform throughout the compacted lift and is at least 95% of maximum density, determined in accordance with Iowa DOT Materials Laboratory Test Method 103.

Other types of compacting equipment may be used provided it is demonstrated that equivalent compaction results will be obtained using a variety of soil types and moistures normally encountered, and demonstrations shall be such that results can be compared.

For Type A compaction, equivalent compaction must be recognizable by roller penetration or other significant characteristic.

For other methods or other equipment, a definite approval will be necessary, including any limitations deemed advisable by the Engineer.

Any use of other methods and equipment prior to approval, except for demonstration tests, shall provide 6 inch (150 mm) compacted lifts at 95% of maximum density during which moisture is maintained not drier than 3 percentage points below optimum moisture.

2107.08 COMPACTION WITH MOISTURE AND DENSITY CONTROL.
The contract documents will show areas in which embankments are to be constructed with moisture and density control and the distance below the elevation of the completed grading work to which such methods shall be applied.

Where construction with moisture and density control is indicated in cut sections, the Contractor shall excavate the roadbed below proposed subgrade elevation to a plane 6 inches (150 mm) above the elevation shown for the bottom of the moisture and density control section. The remaining 6 inch (150 mm) layer shall be thoroughly scarified, and the moisture content increased or reduced, as necessary, to bring the moisture throughout this 6 inch (150 mm) layer within the moisture limits specified. This 6 inch (150 mm) layer shall then be compacted to not less than 90% of maximum density determined in accordance with Iowa DOT Materials Laboratory Test Method 103. The remainder of the cut section to the completed grade elevation shall be deposited in layers in accordance with Article 2107.04 and uniformly moistened or dried as necessary to bring each layer within the specified moisture limits. Each layer shall be compacted to not less than 95% of maximum density.

Where construction with moisture and density control is indicated in embankment sections outside cuts, all material in fill above the designated elevation for compaction with moisture and density control shall be deposited in layers in accordance with Article 2107.04 and uniformly moistened or dried as necessary to bring each layer within the specified moisture limits. The first layer placed with moisture and density control shall be compacted to not less than 90% of maximum density determined in accordance with Iowa DOT Materials Laboratory Test Method 103. Each succeeding layer shall be compacted to not less than 95% of maximum density.

The moisture content of each layer of earth to be compacted with controlled moisture and density shall be brought within the specified limits of the optimum moisture content prior to compaction. When it has been determined by field tests that a layer is within the specified moisture limits, compaction shall begin and shall continue until the required density is obtained. If compaction is interrupted or delayed on a layer, the layer shall be brought within the specified moisture limits before compaction is resumed.

2107.09 COMPACTION WITH MOISTURE CONTROL.
The contract documents will show areas in which embankments are to be constructed with moisture control, the distance below the elevation of the completed grading work to which such methods shall be applied, and the moisture limits.

Where construction with moisture control is indicated in cut sections, the Contractor shall excavate the roadbed below proposed subgrade elevation to a plane 6 inches (150 mm) above the elevation shown for the bottom of the moisture control section. The remaining 6 inch (150 mm) layer shall be thoroughly scarified, and the moisture content increased or reduced, as necessary, to bring the moisture throughout this 6 inch (150 mm) layer within the moisture limits specified. This 6 inch (150 mm) layer shall then be compacted as specified in Article 2107.05. The remainder of the cut section shall be deposited in layers in accordance with Article 2107.04 and uniformly moistened or dried as necessary to bring each layer within the specified moisture limits. Each layer shall be compacted as specified in Article 2107.05.

Where construction with moisture control is indicated in embankment sections outside cuts, all material in fill above the designated elevation for compaction with moisture control shall be deposited in layers in accordance with Article 2107.04 and uniformly moistened or dried, as necessary, to bring each layer within the specified moisture limits. All layers placed with moisture control shall be compacted as specified in Article 2107.05.

The moisture content of each layer of earth to be compacted with controlled moisture shall be brought within the specified limits of the optimum moisture content prior to compaction. When it has been determined by field tests that a layer is within the specified moisture limits, compaction shall begin and shall continue until the requirements of Article 2107.05 are obtained. If compaction is interrupted or delayed for more than 1 hour on a layer, the layer shall be brought within the specified moisture limits before compaction is resumed.

2107.10 ROCK FILLS.
When the excavated material consists of rock fragments of such size that the material cannot be placed in layers of the thickness prescribed without crushing, pulverizing, or further breaking down the pieces resulting from the excavation methods, this material may be placed in the embankment in horizontal layers not exceeding 4 feet (1.2 m) in thickness. Each layer shall be placed in a manner that avoids future entrapment of water. In most cases, this will require placement to full embankment width, except for topsoil on the foreslope. Each layer shall be leveled with a suitable dozer and smoothed by choking the surface of the rock with spalls and finer fragments or earth.

The 4 foot (1.2 m) lifts shall not be constructed above an elevation 2 feet (0.6 m) below the finished grade line. The next foot (0.3m) of height of embankment may be placed in one layer using rock spalls and finer fragments which may be satisfactorily consolidated by the dozer and tractor. The last foot (0.3 m) below the finished grade line shall be composed of either suitable earth smoothed and placed in layers not exceeding 8 inches (200 mm) thickness and rolled as hereinbefore specified or special backfill placed as shown in the contract documents. The Contractor shall conduct operations in such a way that the Engineer is given opportunity to take any cross sectional measurement required before the earth cover is placed.

2107.11 GRANULAR BLANKETS.
Where a granular blanket is specified, material meeting the requirements of Section 4133 shall be spread to the width and thickness shown in the contract documents without the use of compaction equipment. The blanket may be constructed in several lifts, but foreign material shall not be incorporated from hauling equipment or other sources. In areas requiring both granular blanket and subdrain backfill, the sequence of operations will be the option of the Contractor. However, contact areas between porous backfill, granular material for subdrains, and granular blankets shall be free from clay or silt.

2107.12 REBUILDING EMBANKMENTS.
A pavement shall not be placed partly on an old and partly on a newly constructed embankment. If the width or position of the existing roadbed is located to cause the condition described above, the part of the old embankment which would otherwise be beneath the pavement shall be removed as below grade excavation to the natural ground line or to a depth of 5 feet (1.5 m) below the proposed finished grade line, whichever is higher, and rebuilt as prescribed for new embankments.

Rebuilding of embankments shall be constructed in accordance with Article 2107.03 unless otherwise specified in the contract documents. This material shall be compacted in accordance with Article 2107.05.

At locations where the width of embankment widening is less than 4 feet (1.2 m), widening material may be placed and shaped to the bottom of pavement or base elevation without compaction other than that obtained with wheels of motor graders and hauling equipment. Placement and compaction may be accomplished in 8 inch (200 mm) lifts parallel to the finished slope, provided the existing slope has been roughened by disking or scarification.

In all cases of embankment widening, surface vegetation shall be removed from slopes against which the widening material is to be placed. This material shall be deposited in accordance with Article 2107.04.

2107.13 COMPACTING TRENCH BOTTOM.
When designated in the contract documents, the Contractor shall excavate the roadbed for the width shown to 1 foot (0.3 m) below subgrade elevation. The next 6 inch (150 mm) depth shall be scarified and compacted as for Type B compaction, unless otherwise specified. When the bottom of the trench has been compacted, the excavation shall be backfilled with suitable material and compacted. If the type of compaction is not specified for this upper 1 foot (0.3 m), Type A compaction will be required on Primary projects and Type B compaction on Secondary projects.

2107.14 USE OF UNSUITABLE SOILS.
Unsuitable soils may be used in embankments in accordance with Standard Road Plan RL-1B, unless otherwise directed by the Engineer. Unless otherwise specified, when used in embankments, all unsuitable material shall be spread in uniform layers not more than 8 inches (200 mm) in loose thickness, and each layer shall be covered with a layer or layers of suitable material.

2107.15 EMBANKMENTS ADJACENT TO CULVERTS AND STRUCTURES.
When the contract documents require construction of an embankment adjacent to a bridge, culvert, or other structure, the Contractor shall construct the compacted embankment to the height shown and to the full width of the roadway. Material for constructing these embankments shall be secured from within the right-of-way or authorized borrow area as directed by the Engineer. Material from within the waterway of bridges or culverts which is too wet to be suitable for compaction shall be wasted and shall not be placed in the embankment.

Embankments adjacent to bridges, culverts, and structures shall be placed with the same precautions and methods as described in Article 2402.09. Moisture control may be required by the contract documents.

If the areas to be occupied by embankments are too small or narrow for the operation of rollers, compaction shall be done with mechanical or pneumatic tampers. At the Contractor's option, the area in which embankment is to be constructed may be enlarged by cutting down the elevation of the old fill for the purpose of increasing the work area a sufficient amount to permit rolling equipment to operate efficiently. When old fill is removed for this purpose, it shall be stepped up to its original height such that each step shall have a horizontal dimension not less than 3 feet (1 m) with a vertical rise.

Flowable mortar may be used for backfilling adjacent to bridges, culverts, and structures at no additional cost. This backfill shall be constructed in accordance with Section 2506.

2107.16 METHOD OF MEASUREMENT.
All excavation in preparation for constructing embankment by compaction with moisture and density control or with moisture control and in preparation for compacting trench bottom and for rebuilding embankment will be included in Class 10 excavation and measured as provided in Article 2102.13. The construction of embankments will not be measured separately for payment except as follows:

A. Compaction with Moisture and Density Control.
The quantity of Compaction with Moisture and Density Control, in cubic yards (cubic meters), will be the quantity shown on the contract documents.

B. Compaction with Moisture Control. 
The quantity of Compaction with Moisture Control, in cubic yards (cubic meters), will be the quantity shown on the contract documents.

When moisture control is required adjacent to culverts and stockpasses, Article 2107.15, the volume will be computed using the formula in Article 2107.16, D. When moisture control is required adjacent to pipe culverts, the volume will be computed as provided in Article 2402.12.

C. Compacting Trench Bottom.
The quantity of Compacting Trench Bottom, in stations (meters), will be the quantity shown on the contract documents. The quantity of Compacting Trench Bottom will be determined along the center line of the roadbed.

D. Compacting Backfill Adjacent to Bridges, Culverts, or Structures.
The quantity of backfill placed and compacted by the grading contractor adjacent to bridges, box culverts, or structures or their extensions will be the quantity obtained by the following formula:

	Q = (4 ft. x L x H) divided by 27 (1.2 m x LxH)
Where:	Q = quantity of compacted backfill in cubic yards (cubic meters);
	L = (1) length in feet (meters) of the culvert or stock pass from back to back of parapet, or (2) length in feet (meters) from back of existing parapet to back of parapet of the extension;
	H = nominal height of structure opening, feet (meters).

E. Granular Material for Blanket and Subdrain.
Granular material for blanket and subdrain will be measured in cubic yards (cubic meters) according to Article 2312.08, A.

F. Water.
Except when compaction with control of moisture and density or moisture is specified, any water required for moistening materials to be placed in embankment will be measured in thousands of gallons (kiloliters) by gauging the contents of the transporting vehicle or by metering the supply. Authorized water for finishing the roadbed will not be measured for payment if a period in excess of 2 calendar days has elapsed between final compaction of a dump area and final finishing of the same area.

Payment for Compaction with Moisture and Density Control, Compaction with Moisture Control, Compacting Trench Bottom, and Compacting Backfill Adjacent to Culverts and Stockpasses will be for plan quantities in conjunction with quantities shown in the contract documents described in Article 2102.13 and under the conditions described therein.

2107.17 BASIS OF PAYMENT.
The construction of the embankment will be paid for as Embankment-In-Place in accordance with Article 2102.14, with the following additions: