Div31.pdf

Lower Rio Grande Flood Control Project North Banker Floodway Levee Improvements Project Hidalgo County, Texas

DIVISION 31-

USIBWC Contract No.: IBM09B0002 EARTHWORK

US INTERNATIONAL BOUNDARY & WATER COMMISSION

GOVERNING TECHNICAL SPECIFICATIONS AND PROVISIONS

DIVISION 31 – EARTHWORK

DIVISION 31-

USIBWC Contract No.: IBM09B0002 EARTHWORK

This Page Intentionally Blank

PREPARING RIGHT OF WAY

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Section 31 10 00

PREPARING RIGHT-OF-WAY

PART 1 G E N E R A L

1.01 SECTION INCLUDES

A. Preparation of project rights-of-way for construction operations by the removal, stockpiling, and disposal of obstructions. Work in this Section shall also include the removal of trees and shrubs and other landscape features not designated for preservation, stumps, curb and gutter, ramp driveways, roadway, paved parking areas, miscellaneous stone, brick, concrete, sidewalks, drainage and irrigation structures, manholes, inlets, abandoned railroad tracks, roadway guard rails, posts, cabling, and associated hardware, scrap iron, all rubbish and debris whether above or below ground except live utility facilities.

1.02 MEASUREMENT AND PAYMENT

A. Unit Prices.

1. Payment for Preparation of Right-Of-Way is on 100-foot station. This price shall be full compensation for all authorized excavation; for undercutting subgrade and reworking or replacing the undercut material; for all hauling; for all work required for disposal of material not used elsewhere on the project and for furnishing all labor, materials, tools, equipment and incidentals necessary to complete the work. Include cost in base unit prices for Preparation Right-Of-Way for the work described in this Section.

2. Refer to Section 01 27 00 - Measurement and Payment for unit price procedures.

B. Reserved.

PART 2 P R O D U C T S - Not Used

PART 3 E X E C U T I O N

3.01 PREPARATION

A. Identify required lines, levels, and datum – coordinate with SPECIFICATION 01 71 00 - Field

Engineering.

B. Notify utility companies of intended construction.

C. Identify and flag surface and aerial utilities.

D. Identify, stake, and flag known utility locations below grade.

E. Upon discovery of unknown or concealed conditions, discontinue work. Notify COR and obtain instructions before proceeding in such areas.

F. Upon discovery of unknown or concealed conditions, discontinue work. Notify COR.

3.02 PROTECTION

A. Protect the following from damage or displacement:

1. Trees, shrubs, lawns, existing structures, and other features outside of grading limits.

2. Utilities either above or below grade, which are to remain.

PREPARING RIGHT OF WAY

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3.03 CLEARING

A. Conform to the requirements of Section 31 23 30 – Clearing and Grubbing and the following.

B. In areas receiving embankment, remove obstructions not designated for preservation to two-feet (2’) below natural ground.

C. In areas to be excavated, remove obstructions to two-feet (2’) below the excavation level.

D. In all other areas, remove obstructions to one-foot (1’) below natural ground.

3.04 STORM DRAINAGE AND IRRIGATION FACILITIES

A. Remove designated culverts, storm sewers, manholes, inlets, irrigation pipes, and irrigation control structures in proper sequence to maintain traffic, drainage, irrigation.

B. The remaining ends of all storm sewers, culverts, and conduits designated to be abandoned shall be plugged with an adequate quantity of concrete to form a tight closure.

3.05 EXCAVATION

A. Excavation shall include all materials encountered regardless of their nature or of the manner in which they are removed

B. Holes remaining after the removal of obstructions, objectionable material, trees, shrubs, etc., shall be backfilled and tamped in accordance with Section 31 31 60 – Excavation and Backfill for Structures.

3.06 COMPLETION

A. Contractor shall complete the operation of preparing right-of-way by blading, bulldozing, or other compliance-confirmed method(s), such that the prepared rights-of-way shall be free of holes, ditches, and other abrupt changes in elevation or irregularities of contour.

3.06 SURPLUS MATERIALS

A. All materials in excess of that required for completion of the Work as specified in other Sections or designated as debris, shall be considered surplus and become the property of the Contractor and shall be removed from the right-of-way. Disposal operations shall be in accordance with SPECIFICATION 01 57 00 – Temporary Erosion, Sedimentation and Environmental Controls.

END OF SECTION

REMOVING EXISTING PAVEMENTS AND STRUCTURES

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Section 31 22 10

A. Removing concrete pavement, asphaltic concrete pavement, and base courses.

B. Removing concrete curbs, concrete curbs and gutters, sidewalks and driveways.

C. Removing pipe culverts and storm sewers.

D. Removing existing inlets and manholes.

E. Removing miscellaneous structures of concrete or masonry.

1. Include the cost of work performed under this Section in the cost in base unit prices for Preparation Right-Of-Way.

B. Reserved

1.03 REGULATORY REQUIREMENTS

A. Conform to SPECIFICATION 01 57 00 – Temporary Erosion, Sedimentation and Environmental Controls, applicable codes, and local laws for disposal of debris.

B. Coordinate clearing work with utility companies.

1.04 SUBMITTALS

A. Conform to the requirements of Section 01 33 00 – Submittal Procedures.

A. Obtain advance compliance-confirmation from COR for dimensions and limits of removal work; this may require advance coordination and meetings by the USIBWC with the facility owner. Submit preSubmittals in accordance with the applicable portions of SPECIFICATION 01 33 00 – Submittals.

B. Locate and identify buried utilities prior to commencing work; notify COR if there are any utilities encountered that were not identified in the plans to determine method of handling. Identification shall be by flagging and offset staking.

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3.02 PROTECTION

1. Adjacent public and private property.

2. Trees, plants, and other landscape features designated to remain.

3. Utilities designated to remain.

4. Benchmarks, monuments, and existing structures designated to remain.

3.03 REMOVALS

A. Remove pavement and structures by methods that will not damage underground utilities. Do not use a drop hammer near existing underground utilities.

C. Minimize amount of earth loaded during removal operations.

D. Where existing pavement is to remain, make straight saw cuts in existing pavement to provide clean breaks prior to removal. Do not break concrete pavement or base with drop hammer unless concrete or base has been saw cut to a minimum depth of 2-inches.

E. Where street and driveway saw cut locations coincide or fall within 3-feet of existing construction or expansion joints, break out to existing joints.

F. Remove sidewalks and curbs to nearest existing dummy, expansion, or construction joint.

G. Where existing end of pipe culvert or end of sewer is to remain, install and 8-in-thick masonry plug in pipe end prior to backfill.

3.04 BACKFILL

A. Backfill of removal areas shall be in accordance with requirements of Section 02 31 60 – Excavation and Backfill of Structures.

3.05 DISPOSAL

A. Disposal shall in accordance with requirements of SPECIFICATION 01 57 00 – Temporary Erosion, Sedimentation and Environmental Controls.

B. Remove debris, rubbish, and extracted plant material from the site in accordance with requirements of

SPECIFICATION 01 57 00 - Temporary Erosion, Sedimentation and Environmental Controls.

CLEARING AND GRUBBING

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Section 31 23 30

A. Removing surface debris and rubbish.

B. Clearing site of plant life and grass.

C. Removing trees and shrubs.

D. Removing root system of trees and shrubs.

1. No Separate payment will be made for work performed under this Section. Include cost of work performed under this Section in the base unit prices bid for Preparation Right-Of-Way.

1.03 REGULATORY REQUIREMENTS

A. Conform to applicable codes for disposal of debris.

B. Coordinate clearing work with utility companies.

1.04 SUBMITTALS

A. Conform to the requirements of Section 01 33 00 – Submittal Procedures.

A. Verify that existing plant life and features designated to remain are identified and tagged. Submit preSubmittals in accordance with the applicable portions of SPECIFICATION 01 33 00 – Submittals.

1. Living trees located 3 feet or more outside of the intersection of side slopes and original ground line.

2. Plants other than trees and landscape features designated to remain.

3. Utilities designated to remain.

4. Bench marks, monuments, and existing structures designated to remain.

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3.03 CLEARING

A. Remove stumps, main root ball, and root system to:

1. A depth of 24 inches below the finished subgrade elevation in the area bounded by lines two feet behind back of curbs.

2. A depth of 24 inches below the finished surface of the required cross section for other areas.

B. Clear undergrowth and deadwood without disturbing subsoil.

C. Remove vegetation from top soil scheduled for reuse.

3.04 REMOVAL

A. Remove debris, rubbish, and extracted plant material life from the site in accordance with requirements of SPECIFICATION 01 57 00 - Temporary Erosion, Sedimentation and Environmental Controls.

REMOVING OLD STRUCTURES

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Section 31 31 40

A. This Item shall govern for the removal and disposal of old structures or portions of old structures, as noted on the drawings, and shall include all excavation and backfilling necessary to complete the removal. The work shall be done in accordance with this Item.

A. Unit Price. If identified in the Contract Drawings, this will be paid as each individual structure to be removed. Pipe structures will be measured as each structure. Removal shall include all appurtenances as noted in the drawings.

C. Refer to Section 01 27 00 – Measurement and Payment for Unit Price Procedures.

1.03 REFERENCES – Not Used

PART 2 P R O D U C T S – Not Used

3.01 PIPE, CULVERTS OR SEWERS

A. Pipe for reuse shall be removed by careful excavation of all material on the top and sides so that the pipe will not be damaged. Removal of all appurtenances shall be included with pipe removal. Those pipe which are deemed unsatisfactory for reuse by the COR may be removed in any manner the Contractor may select.

3.02 CONCRETE, BRICK OR STONE STRUCTURES

A. Unless otherwise shown on the drawings or compliance-confirmed by the COR, structures or portions of structures shall be removed by breaking the material into sizes capable of being safely removed by available equipment. Blasting may be used only with the compliance-confirmation of the COR.

B. Portions of structures below the permanent ground line, which will not interfere in any manner with the proposed construction, may be left in place, but removal shall be carried at least two (2) feet below the permanent ground line and neatly squared off. Reinforcement shall be cut off flush with the surface.

3.03 STEEL STRUCTURES

A. Steel structures or steel portions of structures shall be dismantled in sections as shown on the drawings or as compliance-confirmed by the COR . Sections shall be of such weight and dimensions which will permit convenient handling, hauling and storing. Dismantling shall be governed by the following:

1. Steel designated for sale to the Contractor may be dismantled by flame-cutting or other methods compliance-confirmed by the COR.

2. Steel to be retained by the GOVERNMENT shall be dismantled by removing rivets and bolts by cutting the heads with a "cold cut" and punching or drilling them from the hole. Welded connections shall be arc-air gouged. Welded splices shall be flame-cut along a straight line at the splice. Other methods that will not damage the members for reuse may be compliance-confirmed by the COR.

3. Steel to be re-erected shall be carefully dismantled without damage and matchmarked with paint in accordance with the compliance-confirmed erection drawings. Disassembly shall be done using methods specified above for reusable material.

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3.05 TIMBER STRUCTURES

A. Timber structures or timber portions of structures to be reused shall be removed with as little damage to the timber as possible. The Contractor shall remove all bolts and nails from lumber which is deemed salvageable by the COR.

B. Unless otherwise specified on the plans, timber piles shall be either pulled or cut off at a point not less than two (2) feet below permanent ground line, at the Contractor's option.

3.06 SALVAGE

A. All material such as pipe, timbers, railings, etc., which the COR deems as salvageable for reuse and all structural steel shall be carefully placed in neat piles along the right-of-way at convenient loading points which will not interfere with traffic or construction or delivered to a location shown on the plans. All of these materials shall be the property of the GOVERNMENT.

B. The I-beams, girders, stringers, etc., which are to be put in storage or specified for reuse shall be blocked off the ground in an upright position to protect the members against damage.

C. Materials, other than structural steel, which are not deemed salvageable by the COR shall become the property of the Contractor and shall be removed to disposal sites off the right of way arranged for by the Contractor and compliance-confirmed by the COR or otherwise disposed of in a manner satisfactory to the COR r.

D. The Contractor, with compliance-confirmation of the COR, will be permitted to use materials removed under this Item for the construction of detour structures. The Contractor shall dismantle and stack or dispose of the materials as required above as soon as the new structure is opened for traffic.

3.07 BACKFILL

A. All excavation made in connection with this Item and all openings below the natural ground line caused by the removal of old structures or portions thereof shall be backfilled to the level of the original ground line, unless otherwise provided on the plans.

B. That portion of the backfill which will support any portion of the roadbed or embankment shall be placed in layers of the same thickness as those required for placing embankment. Material in each layer shall be wetted uniformly if required and shall be compacted to the density required in the adjoining embankment. In places inaccessible to blading and rolling equipment, mechanical or hand tamps or rammers shall be used to obtain the required compaction.

C. That portion of the backfill which will not support any portion of the roadbed or embankment shall be placed in layers not more than ten (10) inches in depth (loose measurement) and shall be compacted to a density comparable with the adjacent undisturbed material.

EXCAVATION

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Section 31 31 50

A. Excavation of materials from levee embankments, roadways, roadside ditches, and channels in the areas shown on the drawings.

1. Payment for excavation is on a cubic yard basis in its original position as computed by the method of average end areas. Shrinkage or swellage factors will not be considered in determining the calculated quantities. This price shall be full compensation for all authorized excavation; for undercutting subgrade and reworking or replacing the undercut material; for all hauling; for all work required for disposal of material not used elsewhere on the project and for furnishing all labor, materials, tools, equipment and incidentals necessary to complete the work.

B. Stipulated Price (Lump Sum). If the Contract is a Stipulated Price Contract, payment for work in this

Section is included in the total Stipulated Price.

1.03 REFERENCES

A. ASTM D 698 - Test Methods for Moisture-Density Relationships of Soils and Soil-Aggregate Mixtures

Using 5.5 Pound (2.49 kg) Rammer, 12-inches (304.88 mm) Drop.

B. ASTM D 1556 - Density of Soil in Place by the Sand-Cone Method.

C. ASTM D 2216 - Test Method for Laboratory Determination of Water (Moisture) Content of Soil, Rock, and Soil Aggregate Mixtures.

D. ASTM D 2922 - Test Methods for Density of Soil and Soil-Aggregate in Place by Nuclear Methods

(Shallow Depth).

E. ASTM D 3017 - Test Method for Moisture Content of Soil and Soil Aggregate in Place by Nuclear

Methods (Shallow Depth)

F. ASTM D 4318 - Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils.

PART 2 P R O D U C T S

2.01. MATERIALS

1. Provide topsoil conforming to requirements of Section 31 91 10 - Topsoil.

2. Provide backfill which is excavated material, graded free of roots, lumps greater than 6 inches, rocks larger than 3 inches, organic material, and debris.

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3. Provide structural backfill which is select material meeting the following requirements:

a. Plasticity index: not less than 12 nor more than 20.

b. Maximum liquid limit: 45.

4. Provide levee backfill which is select material meeting the following requirements:

a. Plasticity index: not less than 10 nor more than 30.

b. Maximum liquid limit: 45.

A. Identify required lines, levels, and datum – coordinate with SPECIFICATION 01 71 00 - Field

Engineering.

B. Notify utility companies of intended construction.

C. Identify and flag surface and aerial utilities.

D. Identify, stake, and flag known utility locations below grade.

E. Upon discovery of unknown or concealed conditions, discontinue work. Notify COR and obtain instructions before proceeding in such areas.

F. Obtain compliance-confirmation of COR of top soil quality before excavating and stockpiling.

1. Trees, shrubs, lawns, existing structures, and other features outside of grading limits.

2. Utilities either above or below grade, which are to remain.

3.03 TOPSOIL REMOVAL

A. Strip off topsoil from the area to be excavated to a minimum depth of 6 inches, unless indicated otherwise on the Drawings.

B. Stockpile topsoil in a designated location for reuse. Stockpile topsoil to depth not exceeding 8 feet.

Cover to protect from erosion.

3.04 SOIL EXCAVATION

A. Excavation shall include all materials encountered regardless of their nature or of the manner in which they are removed.

B. All excavation shall be performed as specified herein and the completed excavation shall conform to the alignment, grades and typical sections as shown on the plans or project cross sections or as established by the COR

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C. All slopes shall be accurately shaped, and care shall be taken that no material is loosened below or outside the required slopes. Exceptions shall be those slopes in rock or other material where, in the judgment of the COR, some variation may be permitted.

1. Rock Cuts. The Contractor shall have the following options:

a. Non-homogeneous Rock.

i. Excavate to finish subgrade elevation, manipulate and compact the subgrade in accordance with Section 31 33 00 – Embankment without removal.

ii. Excavate below grade (undercutting) and replace with embankment material compliance-confirmed by the COR. Compaction shall be in accordance with Section 31 33 00 – Embankment.

b. Homogeneous Rock.

i. Excavate to finish subgrade elevation.

ii. Excavate to finish subgrade elevation, manipulate and compact the subgrade in accordance with Section 31 33 00 – Embankment without removal.

iii. Excavate below grade (undercutting) and replace with embankment material compliance-confirmed by the COR. Compaction shall be in accordance with Section 31 33 00 – Embankment.

2. Earth Cuts

a. When base and/or pavement structure is placed under this project, all earth cuts shall be scarified to a uniform depth of at least 6 inches below the required finished subgrade elevation for the entire roadbed width.

b. The material shall be mixed and reshaped by blading and then sprinkled and rolled in accordance with Section 31 33 00 – Embankment or as shown on the drawings.

D. When excavated materials, including topsoil, are utilized in constructing the required embankment sections, payment for placement will be made under the pertinent placement specification.

E. Backfill with excavated materials and compact to requirements of Section 31 33 00 - Embankment.

F. Record location and plug and fill inactive water and oil wells. Conform to Texas State Health

Department, Texas Water Commission, and Texas Railroad Commission requirements. Notify COR prior to plugging wells.

G. At intersections, grade back at minimum slope of one inch per foot. Produce a smooth riding junction with intersecting street. Maintain proper drainage.

H. If an area is inadvertently over excavated, fill the area in accordance with requirements of Section 31

33 00 - Embankment at no additional cost to the Government.

I. Unsuitable excavation and excavation in excess of that needed for construction shall be known as "Waste" and shall become the property of the Contractor to be disposed of by him outside the limits of the right of way. Unsuitable material encountered below subgrade elevation in cut sections, when declared "Waste" by the COR, shall be replaced with material from the excavation or with other suitable

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3.05 COMPACTION

A. Maintain optimum moisture content of subgrade to attain required density.

B. Compact to following minimum densities at a moisture content of optimum to 3 percent above optimum as determined by ASTM D 698, unless otherwise indicated on the Drawings:

1. Areas under future paving and shoulders: Minimum density of 95 percent of maximum dry density.

2. Other areas: Minimum density of 90 percent of maximum dry density.

3.06 TOLERANCES

A. Any deviation in excess of 0.1 foot in cross section and 0.1 foot in 16 feet measured longitudinally shall be corrected by loosening, adding or removing the material, reshaping and re-compacting by sprinkling and rolling.

3.07 FIELD QUALITY CONTROL

A. Tests and analysis of soil materials will be performed in accordance with ASTM D 4318, ASTM D

2216, and ASTM D 698 under provisions of SPECIFICATION 01 46 00 - Quality Control / Quality Assurance.

B. Compaction testing will be performed in accordance with ASTM D 1556 or ASTM D 2922 and ASTM

D 3017 under provisions of SPECIFICATION 01 46 00 - Quality Control / Quality Assurance.

C. A minimum of three tests will be taken for each 1000 linear feet per lane of Embankment.

D. If tests indicate work does not meet specified compaction requirements, recondition, re-compact, and retest at no additional cost to the Government.

3.08 PROTECTION

A. Prevent erosion at all times. Maintain ditches and cut temporary swales to allow natural drainage in order to avoid damage to Embankment. Do not allow water to pond.

B. Distribute construction traffic evenly over compacted areas, where practical, to aid in obtaining uniform compaction. Protect exposed areas having high moisture content from wheel loads that cause rutting.

C. Maintain excavation and embankment areas until start of subsequent work. Repair and re-compact slides, washouts, settlements, or areas with loss of density.

EXCAVATION AND BACKFILL FOR STRUCTURES

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Section 31 31 60

PART 1 GENERAL

1.1 SECTION INCLUDES

Excavate for placement and construction of structures and backfill structures. Cut and restore pavement.

1.2 MEASUREMENT AND PAYMENT

A. Measurement

No Payment will be made for structural excavation and backfill under this section.

Include cost of work performed under this section in unit price or lump sum Construction of Structures.

1. Structural Excavation

Unless shown on the plans as a pay item, structural excavation quantities shown are for information purposes only.

When structural excavation is specified as a pay item, structural excavation for pipe headwalls, inlets, manholes, culvert or storm drain extensions less than 15

ft. long, bridge abutments, retaining walls, and side road and private entrance pipe culverts will not be measured. No allowance will be made for variance from plans quantity incurred by an alternate bid.

When specified as a pay item, structural excavation will be measured by the cubic yard as computed by the average end areas method. Excavation diagrams on the plans take precedence over the provisions of this Article.

a. Boundaries of Measurement

1) Pipe

a) Pipe up to 42 Inches - For pipe 42 in. or less in nominal or equivalent diameter, no material outside of vertical planes 1 ft. beyond and parallel to the horizontal projection of the outside surfaces of the pipe will be included.

b) Pipe Larger than 42 Inches - For pipes larger than 42-in.

nominal or equivalent diameter, no material outside of vertical planes located 2 ft. beyond and parallel to the horizontal projection of the outside surfaces of the pipe will be included.

Quantities for excavation in fill above natural ground include 1 ft.

above the top of the pipe regardless of the height of completed fill. Excavation for pipe will be measured between the extreme ends of the completed structure including end appurtenances as shown on the plans and from centerline to centerline of inlets, manholes, etc.

2) Structural Plate Structures

No material outside of vertical planes 3 ft. beyond and parallel to the horizontal projection of the outside surfaces of the structure will be included. When the quality of the existing soil or

USIBWC Contract No.: IBM09B0002 Page 3131.60 - 2 embankment is less than that of the proposed backfill material, the limits of measurement will be extended to vertical planes located 1/2 of the span beyond the horizontal projection of the outside surfaces of the structure.

3) Footings, Walls, Boxes, and Other Excavation

No material outside of vertical planes 1 ft. beyond and parallel to the edges of the footings or outside walls will be included whether or not a cofferdam or shoring is used. When plans provide the option of cast-in-place or precast boxes, measurement will be based on the cast-in-place option.

Where excavation in addition to that allowed for the footings is required for other portions of the structure, measurement for the additional excavation will be limited laterally by vertical planes 1

ft. beyond the face of the member and parallel to it, and vertically to a depth of 1 ft. below the bottom of the member.

4) Excavation near Roadways and Channels

At structure sites other than culverts and pipe excavations, the measurement of structural excavation will include only material below or outside the limits of the completed road or channel excavation. Roadway and channel excavation will be paid under section 31 31 50 -“Excavation.” For culverts except side road and private entrance culverts, excavation within the limits of the structure and below or outside the limits of the completed roadway excavation will be measured as structural excavation.

b. Falsework

No measurement will be made for excavation necessary for placing forms or falsework that exceeds the limits given in paragraph a Boundaries of Measurement.

c. Swelling

Measurement will not include materials removed below footing grades to compensate for anticipated swelling due to pile driving, nor will it include material required to be removed due to swelling beyond the specified limits during pile driving operations.

d. Cave-ins

Measurement will not include additional volume caused by slips, slides, cave-ins, silting, or fill material resulting from the action of the elements or the Contractor’s operation.

e. Undercut

Where rock or other incompressible or unstable material is undercut to provide a suitable foundation for pipe or box sections, such material below grade directed to be removed will be measured for payment.

f. Grade Change

Additional measurement will be made of the volume of excavation involved in the lowering or raising of the elevation of a footing, foundation, or structure unit, when such grade change is authorized.

2. Cement-Stabilized Backfill

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Cement-stabilized backfill will be measured by the cubic yard as shown on the plans.

3. Cutting and Restoring Pavement

Cutting and restoring pavement will be measured by the square yard as shown on the plans. Excavation below pavement or base will be measured as structural excavation of the pertinent type.

B. Payment

1. Structural Excavation

Unless specified as a pay item, structural excavation and backfill performed and material furnished in accordance with this Item will not be paid for directly but are subsidiary to pertinent Items.

When structural excavation is specified as a pay item, the excavation and backfill work performed and materials furnished will be paid for at the unit price bid for “Structural Excavation,” “Structural Excavation (Box),” “Structural Excavation (Pipe),” and “Structural Excavation (Bridge).” This price includes concrete to compensate for excavation that has extended below grade for bridge foundations and retaining walls, and backfilling and compacting areas that were removed as part of structural excavation.

Cofferdams or other measures necessary for supporting excavations less than 5

ft. deep will not be measured or paid for directly but will be subsidiary to the Contract.

Foundation seal concrete for cofferdams, when required by the COR, will be paid for as provided in the pertinent Items. Seal placed for the convenience of the Contractor will not be paid for.

When structural excavation is specified as a pay item, a partial payment of 50% of the bid price will be made for structural excavation completed to the satisfaction of the COR but not backfilled. The remaining amount will be paid upon completion of backfilling. When the Contractor elects to excavate beyond plan requirements, no measurement will be made of the additional volume.

2. Removal and Replacement of Unsuitable or Incompressible Material

Removal and replacement of material will be paid for if directed. Removal and replacement of material or placement of special material made necessary by the softening of founding material due to the Contractor’s sequence of work or operation, will be at the Contractor’s expense. Special material used or additional excavation made for the Contractor’s convenience will not be paid for.

a. Structural Excavation as a Pay Item

Where special materials are not required or specified, payment for the removal and replacement of unstable or incompressible material will be made at a price equal to 200% of the unit price bid per cubic yard for Structural Excavation. When the Contractor elects to remove and replace material deeper than directed, no measurement will be made on that portion below the directed elevation. This price is full compensation for removing the unstable or incompressible material; furnishing, hauling, placing, and compacting suitable replacement material; and equipment, labor, tools, and incidentals.

When the plans specify or when the COR directs the use of special materials such as flexible base, cement-stabilized base, cement-stabilized backfill, or other special material, payment for excavation below footing grades will be made at the unit price bid for Structural

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Excavation. Payment for furnishing, hauling, placing, and compacting the flexible base, cement-stabilized base, cement-stabilized backfill, or other special materials will be made at the unit price bid for these items in the Contract.

b. Structural Excavation Not a Pay Item

Where special materials for backfill are not required or specified, payment for the authorized removal and replacement of unstable or incompressible material will be measured and paid for at $15 per cubic yard of material removed. This price is full compensation for removing the unstable or incompressible material; furnishing, hauling, placing, and compacting suitable replacement material; and equipment, labor, tools, and incidentals.

When the plans specify or when the COR directs the use of special materials such as flexible base, cement-stabilized base, cement-stabilized backfill, or other special material, excavation below the footing grades will be paid for at $10 per cubic yard. Payment for furnishing, hauling, placing, and compacting the flexible base, cement-stabilized base, cement-stabilized backfill, or other special materials will be made at the unit price bid for these Items.

3. Lowering of a Structure Foundation

If the COR requires a structure foundation to be lowered to an elevation below the grade shown on the plans, overexcavation will be paid in accordance with Table 1.

Table 1 Payment for Required Overexcavation

Payment terms Variance of revised footing grade from plan grade Variance of revised footing grade from plan grade “Structural Excavation” is a bid item

“Structural Excavation” is not a bid item

Up to and including 5 ft.

Unit price equal to 115% of unit price bid for “Structural Excavation”

$10 per cubic yard

Over 5 ft. up to 10 ft.

Unit price equal to 125% of unit price bid for “Structural Excavation”

$12 per cubic yard

Over 10 ft.

In accordance with Article 9.4, “Payment for Extra Work”

4. Cement-Stabilized Backfill

Cement-stabilized backfill will not be paid for directly but will be subsidiary to pertinent items.

5. Cutting and Restoring Pavement

Cutting and restoring pavement will not be paid for directly but will be subsidiary to pertinent items. Work done to repair damage to base or pavement incurred outside the limits shown on the plans, or the limits authorized by the COR, will not be measured for payment.

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The unit prices bid are full compensation for excavation including removing obstructions and plugging drainage systems; bedding and backfilling including placing, sprinkling and compaction of material; soundings; cleaning and filling seams; constructing and removing cofferdams; de-watering, sheeting, or bracing excavations up to and including 5 ft. deep; pumps; drills; explosives; disposition of surplus material; cutting pavement and base to neat lines; and materials, hauling, equipment, labor, tools, and incidentals.

Flowable backfill will be paid for as provided in section 03 04 01 - “Flowable Backfill.” Protection methods for open excavations deeper than 5 ft. will be measured and paid for as required under section 03 04 02 -“Trench Excavation Protection,” or section 03 04 03 -“Temporary Special Shoring.”

1.3 REFERENCES

A. AASHTO Standard Specifications for Highway Bridges

B. AASHTO LRFD Bridge Design Specifications

C. TxDOT Departmental Material Specifications

1. DMS-4600 - Hydraulic Cement

D. TxDOT Tests

1. Tex-120-E - Soil-Cement Testing

E. Texas Manual on Uniform Traffic Control Devices (TMUTCD)

1.4 SUBMITTALS

A. Conform to Section 01 33 00 - Submittal Procedures.

PART 2 PRODUCTS

Use materials that meet the requirements of the following Items:

A. 03 04 01 -“Flowable Backfill”

B. 03 04 21, “Hydraulic Cement Concrete”

C. DMS-4600, “Hydraulic Cement.”

PART 3 EXECUTION

3.1 EXCAVATION.

A. General

Excavate to the lines and grades shown on the plans or as directed. Provide slopes, benching, sheeting, bracing, pumping, and bailing as necessary to maintain the stability and safety of excavations up to 5 ft. deep. Excavation protection for trench excavations deeper than 5 ft. are governed by SPECIFICATION 01 39 00, Safety. If temporary special shoring is required, the Contractor shall prepare and submit a detailed engineered plan and drawing by a Texas-registered professional engineer. Use satisfactory excavated material as backfill or as embankment fill in accordance with 31 33 00 -“Embankment.” Dispose of material not incorporated into the final project off the right of way in accordance with federal, state, and local regulations.

When excavating for installation of structures across private property or beyond the limits of the embankment, keep any topsoil removed separate, and replace it, as nearly as feasible, in its original position. Restore the area to an acceptable condition.

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Excavate drilled shafts in accordance with 03 04 16 -“Drilled Shaft Foundations.”

1. Obstructions

Remove obstructions to the proposed construction, including trees and other vegetation, debris, and structures, over the width of the excavation to a depth of 1 ft. below the bottom of excavation. If abandoned storm drains, sewers, or other drainage systems are encountered, remove as required to clear the new structure, and plug in an complliance-confirmed manner. After removing obstructions, restore the bottom of the excavation to grade by backfilling in accordance with this Item. Dispose of surplus materials in accordance with federal, state, and local regulations.

2. Excavation in Streets

When structures are installed in streets, highways, or other paved areas, cut pavement and base to neat lines. Restore pavement structure after completion of excavation and backfilling.

Maintain and control traffic in accordance with the complliance-confirmed traffic control plan and the 2006 Texas Manual on Uniform Traffic Control Devices.

3. Utilities

Conduct work with minimum disturbance of existing utilities, and coordinate work in or near utilities with the utility Owners. Inform utility Owners sufficiently before work begins to allow them time to identify, locate, reroute, or make other adjustments to utility lines.

Avoid cutting or damaging underground utility lines that are to remain in place. If damage occurs, promptly notify the utility company. If an active sanitary sewer line is damaged during excavation, provide temporary flumes across the excavation while open, and restore the lines when backfilling has progressed to the original bedding lines of the cut sewer.

4. De-Watering

Do not construct or place structures in the presence of water unless complliance-confirmed. Place precast members, pipe, and concrete only on a dry, firm surface. Remove water by bailing, pumping, well-point installation, deep wells, underdrains, or other complliance-confirmed method.

If structures are complliance-confirmed for placement in the presence of water, remove standing water in a manner that does not allow water movement through or alongside concrete being placed. Do not pump or bail while placing structural concrete or for a period of at least 36 hr. thereafter unless from a suitable sump separated from the concrete work. Pump or bail during placement of seal concrete only to the extent necessary to maintain a static head of water within the cofferdam. Do not pump or bail to de-water inside a sealed cofferdam until the seal has aged at least 36 hr.

If the bottom of an excavation cannot be de-watered to the point that the subgrade is free of mud or it is difficult to keep reinforcing steel clean, place a stabilizing material in the bottom of the excavation. Stabilizing material may be flexible base, cement-stabilized base or backfill, lean concrete, or other complliance-confirmed material. If lean concrete is used, provide concrete with at least 275 lb. of cement per cubic yard, and place to a minimum depth of 3 in.

Stabilizing material placed for the convenience of the Contractor will be at the Contractor’s expense.

B. Bridge Foundations and Retaining Walls

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Do not disturb material below the bottom of footing grade. Do not backfill to compensate for excavation that has extended below grade. If excavation occurs below the proposed footing grade, fill the area with concrete at the time the footing is placed. The additional concrete placed will be at the Contractor’s expense.

If requested, take cores to determine the character of the supporting materials. Provide an intact sample adequate to judge the character of the founding material. Take these cores when the excavation is close to completion. Cores should be approximately 5 ft.

deeper than the proposed founding grade.

If the founding stratum is rock or other hard material, remove loose material, clean, and cut to a firm surface that is level, stepped, or serrated, as directed. Clean out soft seams, and fill with concrete at the time the footing is placed.

If the material at the footing grade of a retaining wall, bridge bent, or pier is a mixture of compressible and incompressible material, do not place the foundation until the COR has inspected the excavation and authorized changes have been made to provide a uniform bearing condition.

C. Cofferdams

The term “cofferdam” designates any temporary or removable structure constructed to hold surrounding earth, water, or both out of the excavation whether the structure is formed of soil, timber, steel, concrete, or a combination of these. Cofferdams may require the use of pumping wells or well points for dewatering.

For sheet-pile or other types of cofferdams requiring structural members, submit details and design calculations bearing the seal of a licensed professional COR for review before constructing the cofferdam. The COR reserves the right to reject designs. Design structural systems to comply with the AASHTO Standard Specifications for Highway Bridges or AASHTO LRFD Bridge Design Specifications. Interior dimensions of cofferdams must provide sufficient clearance for the construction, inspection, and removal of required forms and, if necessary, sufficient room to allow pumping outside the forms. In general, extend sheet-pile cofferdams well below the bottom of the footings, and make concrete seals as well braced and watertight as practicable.

For foundation seals, use Class E concrete unless otherwise specified. Place concrete foundation seals in accordance with 03 04 20 - “Concrete Structures.” Seals placed for the convenience of the Contractor will be at the Contractor’s expense.

When the COR judges it to be impractical to de-water inside a cofferdam and a concrete seal is to be placed around piling driven within the cofferdam, make the excavation deep enough to allow for swelling of the material at the base of the excavation during pile-driving operations. After driving the piling, remove swelling material to the bottom of the seal grade. Where it is possible to dewater inside the cofferdam without placing a seal, remove the foundation material to exact footing grades after driving piling. Do not backfill a foundation to compensate for excavation that has been extended below grade; fill such areas below grade with concrete at the time the seals or footings are placed.

Unless otherwise provided, remove cofferdams after completing the substructure without disturbing or damaging the structure.

D. Culverts and Storm Drains

When the design requires special bedding conditions for culverts or storm drains, an excavation diagram will be shown on the plans. Do not exceed these limits of excavation.

Unless otherwise shown on the plans, construct pipe structures in an open cut with vertical sides extending to a point 1 ft. above the pipe. When site conditions or the plans do not prohibit sloping the cut, the excavation may be stepped or laid back to a stable

USIBWC Contract No.: IBM09B0002 Page 3131.60 - 8 slope beginning 1 ft. above the pipe. Maintain the stability of the excavation throughout the construction period.

For pipe to be installed in fill above natural ground, construct the embankment to an elevation at least 1 ft. above the top of the pipe, and then excavate for the pipe.

1. Unstable Material

When unstable soil is encountered at established footing grade, remove the material to a depth of no more than 2 ft. below the grade of the structure unless the COR authorizes additional depth. Replace soil removed with stable material in uniform layers at most 8 in. deep (loose measurement). Each layer must have enough moisture to be compacted by rolling or tamping as required to provide a stable foundation for the structure.

When it is not feasible to construct a stable foundation as outlined above, use special materials such as flexible base, cement-stabilized base, cement-stabilized backfill, or other complliance-confirmed material.

2. Incompressible Material

If rock, part rock, or other incompressible material is encountered at established footing grade while placing prefabricated elements, remove the incompressible material to 6 in. below the footing grade, backfill with an complliance-confirmed compressible material, and compact in accordance with paragraph 3.3 Backfill.

3.2 SHAPING AND BEDDING

For precast box sections, place at least 2 in. of fine granular material on the base of the excavation before placing the box sections. For pipe installations, use bedding as shown in Figure 1. Use Class C bedding unless otherwise shown on the plans. The COR may require the use of a template to secure reasonably accurate shaping of the foundation material. Where cement-stabilized backfill is indicated on the plans, undercut the excavation at least 4 in. and backfill with stabilized material to support the pipe or box at the required grade.

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Figure 1 Bedding diagrams

3.3 BACKFILL

A. General

As soon as practical, backfill the excavation after placement of the permanent structure.

Use backfill free from stones large enough to interfere with compaction; large or frozen lumps that will not break down readily under compaction; and wood or other extraneous material. Obtain backfill material from excavation or from other sources.

In areas not supporting a completed roadbed, retaining wall, or embankment, place backfill in layers at most 10 in. deep (loose measurement). In areas supporting a portion of a roadbed, retaining wall, or embankment, place backfill in uniform layers at most 8 in.

deep (loose measurement). Compact each layer to meet the density requirements of the roadbed, retaining wall, embankment material, or as shown on the plans.

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Bring each layer of backfill material to the moisture content needed to obtain the required density. Use mechanical tamps or rammers to compact the backfill. Rollers may be used to compact backfill if feasible.

Cohesionless materials such as sand may be used for backfilling. Compact cohesionless materials using vibratory equipment, waterponding, or a combination of both.

B. Bridge Foundations, Retaining Walls, and Box Culverts

Do not place backfill against the structure until the concrete has reached the design strength required in Section 03 04 21, “Hydraulic Cement Concrete.”

Backfill retaining walls with material meeting the requirements of 03 04 23 - “Retaining Walls.” Backfill around bridge foundations and culverts using material with no particles more than 4 in. in greatest dimension and with a gradation that permits thorough compaction. Rock or gravel mixed with soil may be used if the percentage of fines is sufficient to fill all voids and ensure a uniform and thoroughly compacted mass of proper density.

Where backfill material is being placed too close to the structure to permit compaction with blading and rolling equipment, use mechanical tamps and rammers to avoid damage to the structure.

Avoid wedging action of backfill against structures. To prevent such action, step or serrate slopes bounding the excavation. Place backfill uniformly around bridge foundations. Place backfill along both sides of culverts equally and in uniform layers.

The COR may require backfilling of structures excavated into hard, erosion-resistant material, and subject to erosive forces, with stone or lean concrete.

Box culverts may be opened to traffic as soon as sufficient backfill and embankment has been placed over the top to protect culverts against damage from heavy construction equipment. Repair damage to culvert caused by construction traffic at no additional expense to the Government.

C. Pipe

After installing bedding and pipe as required, bring backfill material to the proper moisture condition and place it equally along both sides of the pipe in uniform layers at most 8 in. deep (loose measurement). Compact each lift mechanically. Thoroughly compact materials placed under the haunches of the pipe to prevent damage or displacement of the pipe. Continue to place backfill in this manner to the top-of-pipe elevation. Place and compact backfill above the top of the pipe in accordance with Section 3.3A General.

The COR may reject backfill material containing more than 20% by weight of material retained on a 3-in. sieve; with large lumps not easily broken down; or that cannot be spread in loose layers. Material excavated by a trenching machine will generally meet the requirements of this Section as long as large stones are not present.

Where pipe extends beyond the toe of slope of the embankment and the depth of cover provided by backfill to the original ground level is less than the minimum required by the specifications for the type of pipe involved, place and compact additional material until the minimum cover has been provided.

D. Cement-Stabilized Backfill

When shown on the plans, backfill the excavation to the elevations shown with cement-stabilized backfill. Use cement-stabilized backfill that contains aggregate, water, and a minimum of 7% hydraulic cement based on the dry weight of the aggregate, in accordance with Tex-120-E. Use clean sand as aggregate for cement-stabilized backfill unless otherwise shown on the plans. Use only complliance-confirmed aggregate.

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Place cement-stabilized backfill equally along the sides of structures to prevent strain on or displacement of the structure. Fill voids when placing cement-stabilized backfill. Use hand operated tampers if necessary to fill voids.

E. Flowable Backfill

When shown on the plans, backfill the excavation with flowable backfill to the elevations shown. Prevent the structure from being displaced during the placement of the flowable fill, and prevent flowable fill from entering culverts and drainage…