203Excavation and Embankment

Excavation and Embankment

203.1DESCRIPTION

1 This section describes the requirements for excavation, hauling, disposal, placing, shaping, grading, compaction of material; and installing and maintaining settlement platforms.

2 Excavation classifications are as follows:

material sources.

saturated mixtures of soils and or ganic matter from within the construction limits but not associated with culvert installations . Soils or mixtures of soils will be classified as muck excavation only if they cannot be excavated using the same equipment and procedure as used for unclassified excavation.

Classification and removal of unsuitable materials associated with culvert installations is speci fied in Section 206, Excavation and Backfill for Culverts.

or sedimentary rock, which cannot be excavated without blasting or the use of conventional excavating equipment. The limits of rock excavation are based on seismic velocities as defined in the contract and the structural characteristics of the bedrock. Excavation outside these limits is unclassified excavation as defined below.

materials encountered in the work, including excavation from material sources, not classified under other contract pay items.

203.2MATERIALS

203.2.1 Settlement Platform

1 Provide the following materials:

• ½- in [12.5 mm] OD transparent semi rigid tubing with a minimum wall thickness of 1/16-in [2 mm] and minimum 90 psi [620 kPa] rating at 73o F [23° C] • 50/50 mix of water and antifreeze • 2 in x 4 in x 8 ft [ 50 mm x 100 mm x 2.4 m] Standard Grade Lumber • 4 in x 4 in x 8 ft [100 mm x 100 mm x 2.4 m] Standard Grade Lumber • 1 in x 6 in x 10 ft [25 mm x 150 mm x 3 m] #3 Common Board (pine or equivalent)

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• 8 in [200 mm] diameter x 5 ft [1.5 m] PVC casing • 36 in [900 mm] yard stick in increments of inches • 2- Hinges • Hasp • Lock with 2 keys

2 Provide sand for tubing backfill and platform support consisting of free-draining granular material containing no rocks or clay. Ensure 100% of the sand passes the No. 4 [4.75 mm] sieve.

203.3EQUIPMENT—V acant

203.4CONSTRUCTION

203.4.1 General

1 In this section the term “borrow source” refers to the source for excavation materials. For borrow sources, adhere to the requirements of Subsection 106.3, Sources, Sites and Haul Roads.

2 Construct embankments when air temperatures allow compaction to the specified densities. Suspend work during sustained periods of freezing that induce frost in the embankment or excavation.

3 Before beginning excavation activities, construct required fencing in accordance with

4 Before beginning excavation activities, construct contour diversion ditches in accordance with Subsection 215.4.3.7, Contour Diversion Ditches.

5 Perform grading during daylight. Grading may be allowed after dark, provided adequate lighting equipment is provided for the safety of the traveling public and the work force and for inspection.

6 Conform to the neat lines and elevations staked by the engineer . Do not waste excavated materials without approval from the engineer. Conduct grading and related operations without disturbing the terrain outside of the construction limits. Restore disturbed terrain outside of the construction limits and seed with the specified seed mixture at no additional cost to the department.

7 The engineer may require additional excavation where rock, unstable soil, or other unsuitable material is encountered below subgrade. If the material at grade can be finished and compacted, excavation below grade will not be required. Obtain material for backfilling to subgrade from other grading areas. Dispose of unsuitable material at a specified waste site or incorporate into other portions of the work, as approved by the engineer.

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8 Give five working days advance notice before beginning excavation in any borrow source. Do not remove material before cross-sectioning or digital terrain modeling of the site by the engineer.

9 Sequence roadway construction and excavation from borrow sources to minimize the waste of material. If more borrow material is used than is required, causing an excess of excavation material, the excess quantity will be deducted from the excavation volume measured in the borrow source or sources. The department will deduct from monies due the contractor for the royalties on borrow source materials used in excess of the quantities required. Leave borrow areas in a smoothed condition satisfactory to the engineer and conducive to accurate measurements after the excavation is completed.

10 Do not place rocks, broken concrete, or other solid materials in embankments where piling will be installed.

11 If embankment material can be placed on only one side of abutments, wing walls, piers, or culvert head walls, perform compaction without causing overturning or placing excessive pressure against the structure that would cause movement. Until the superstructure is in place, do not place the fill next to a bridge abutment higher than the bottom of the backwall. When embankment material is placed on both sides of a concrete wall or box -type structure, bring the embankment up equally on both sides of the structure.

12 Dispose of excess or unsuitable excavated material (including rock and boulders) that cannot be used in embankments, as specified or approved by the engineer.

13 Construct roadway embankments with loose layers 8 in [200 mm] thick, thoroughly mixed to provide uniform moisture distribution and compacted as specified before placing the next layer. Before compacting, use spreading equipment to obtain a uniform thickness. While compacting, level and manipulate to ensure uniform densit y. Control water use to obtain the required densit y. Route construction equipment uniformly over the entire surface of each layer.

14 When the excavated material consists mainly of rock lar ger than 8 in [200 mm], place the material in maximum lifts of 3.0 ft [1.0 m]. Work each lift for moisture distribution; compact, level and smooth with suitable equipment. Do not construct lifts within 24 in [600 mm] of the finished subgrade. Construct the balance of the embankment with approved material placed and smoothed in accordance with Subsection 203.4.3, Embankment and Cut Areas with Moisture and Density Control.

203.4.2 Benching Requirements

1 When placing embankment material on or against slopes steeper than 1V:4H, bench the existing slope as the new embankment material is brought up in layers. Cut each bench 5 ft [1.5 m] horizontally into the original ground line from the vertical side of the previous cut. Compact materials from the benching with the embankment material.

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203.4.3 Embankment and Cut Areas with Moisture and Density Control

203.4.3.1 General

1 Construct fill in embankments and cut areas with moisture and density control. Perform compaction when soil moisture content is within plus 2 percent to minus 4 percent of the optimum moisture content . Determine maximum densities by Method A as specified in the Materials Testing Manual.

2 When embankment material cannot be tested using Method A as specified in the Materials Testing Manual, place and compact the material using construction methods in accordance with Subsection 203.4.1, Excavation and Embankment, Construction, General, and locate the material at least 24 in [600 mm] below the finished subgrade.

3 In embankment and cut areas, place and compact material above the 6 in [150 mm] scarified layer of moisture and density control to at least 95.0 percent of maximum density.

4 Reprocess and recompact to the specified density embankments damaged by hauling operations or improper drainage, at no additional cost to the department.

5 Remove and replace newly constructed embankments that are soft, yielding, or otherwise unacceptable, at no additional cost to the department.

203.4.3.2 Cut Areas

1 Treat cut areas for moisture and density control to at least the depth of the plane from ditch-bottom to ditch-bottom, not to exceed a depth of 24 in [600 mm] below the finished subgrade. Scarify the lower 6 in [150 mm] of the moisture and density control layer, adjust the moisture content, and compact the material to at least 90.0 percent of maximum density.

203. 4.3.3 Embankment Areas

1 Remove sod, vegetation, and topsoil from embankment foundations, and scarify the surface to a depth of 6 in [150 mm]. Adjust moisture content, and compact material to at least 90.0 percent of maximum density.

203.4.4 Embankments Without Moisture and Density Control

1 Construct embankments specified as not requiring moisture and density control in accordance with Subsection 203.4.1, Excavation and Embankment, Construction, General. Consolidate the material to a uniform consistency by routing the hauling and leveling equipment over each lift. Add water to each lift if the natural moisture is insufficient to aid in the placement compaction. Compact the soil when moist.

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203.4.5 Finishing

1 Sequence finishing work with other operations. Where practical, round the tops of cut slopes to blend with the adjacent terrain.

2 Cut subgrade shoulders and ditch bottoms to eliminate scalloped or ragged lines and grade to drain.

3 Trim inslopes and backslopes to eliminate unsightly humps or hollows, and blend at pipe ends, drilled shaft foundation, and erosion control devices.

4 Remove and dispose of piled boulders, unsuitable material, and other debris as approved by the engineer.

5 Perform finishing operations at a right angle to the slope. Hand raking may be required where finishing work cannot be performed by machine.

203.4.6 Settlement Platform

203.4.6.1 General

1 Notify the engineer at least 14 calendar days prior to the installation of the settlement platforms and indication units.

203.4.6.2 Installation

1 Install the fluid type settlement indicating devices in accordance with the contract at the established elevations and locations. The settlement platforms monitor the amount and rate of settlement that occurs as the embankment is built. Assemble and place settlement platforms prior to any construction activities to ensure settlement is accurately monitored. By doing so, delays in the construction schedule may potentially be avoided. Fill the tubes with a 50% solution of antifreeze and water. Flush all bubbles from the fluid filled tubes. Maintain the integrity of the settlement platforms and read out stations through the use of protective devices.

2 Replace settlement platforms that are damaged due to construction activities, at no additional cost to the department.

Dig trenches for the plastic tube and backfill with the sand blanket material at the direction of the engineer and as shown in the contract. During backfilling operations of the settlement platform, take extreme care to prevent displacement of or damage to the equipment and tubing. Place plastic tubing in a bed of sand and cover with no less than 4 in [100 mm] of sand before backfilling the ditch.

4 Coordination with the engineer will be necessary to ensure settlement has dimin ished based on settlement platform readings, prior to paving operations and/or structure

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construction. Depending on the total measured settlement and the rate of the settlement, construction (i.e. rates and scheduling) may be modified at the direction of the engineer. Do not perform paving operation and/or structure construction unless approved by the engineer.

203.5MEASUREMENT and PAYMENT

203.5.1 General

1 All classifications of excavation will be measured by the engineer in its original position using volumetric measurements in accordance with Subsection 101.5, Definitions. The volumes will be computed when the work is completed. Volumes for authorized excavation below subgrade elevation will be computed by this same method. The volume calculation will be adjusted to remove topsoil quantities.

2 The engineer will measure materials actually excavated, except for excavation resulting from benching operations. Additional excavation required by the engineer, in accordance with Subsection 203.4.1, Excavation and Embankment, Construction, General, will be measured for payment.

3 Where it is impractical to measure material by the volumetric measurement methods because of the erratic location of isolated deposits, the engineer will use acceptable methods involving three-dimensional measurements.

4 For excavation that requires repeated handling before final placement, the engineer will measure each approved handling, including that of materials to be stockpiled and preserved for later use in the work. When repeat handling is for the contractor’s convenience, no additional measurement will be made.

5 The engineer will measure:

[metric ton]. When payment is by weight [mass], the weight [mass] of water added before measuring will not be deducted.

The engineer will not measure overbreak.

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6 In embankment and cut areas, the 6 in [150 mm] of material scarification, adjustment of moisture content, and recompaction to 90.0 percent will not be measured for payment directly and is considered incidental to the various classifications of excavation.

7 The department will pay as follows:

Pay Item

Pay Unit Measure to the Nearest Pay to the Nearest Borrow Special Excavation CY, TON [m3, t] 0.1 ft, 0.05 ton [0.05 m, 0.05 t] CY, 0.05 TON [m3, 0.05 t] Muck Excavation CY [m3] 0.1 ft [0.05 m] CY [m3] Rock Excavation CY [m3] 0.1 ft [0.05 m] CY [m3] Unclassified Excavation CY [m3] 0.1 ft [0.05 m] CY [m3] Settlement Platform EA [Ea] EA [Ea] EA [Ea]

203.5.2 Referenced Sections for Direct Payment

1 When specified, the engineer will measure and pay for:

Subsection 109.4, Extra and Force Account Work.