2402.01 DESCRIPTION.
Excavation for structures shall consist of the removal of all material necessary for construction of the work included in the contract, in conformity with the contract documents. It shall include furnishing, placing, and removal of all cofferdams, shoring, and bracing and removal of all surplus material.

Sounding and test boring data shown in the contract documents were accumulated for design and estimating purposes. Their appearance in the contract documents does not constitute a guarantee that conditions other than those indicated will not be encountered in the excavation or in material penetrated by piling.

If a single contract involves both channel excavation and excavation for structures, none of the excavation included within the volume limits of channel excavation, as shown in the contract documents, shall be included in measurement of excavation for structures.

Excavation for structures to the limits indicated in Article 2402.12 is for pay quantities only.

It is the Contractor's responsibility to provide a safe slope for construction in the conditions encountered.

2402.02 CLEARING AND GRUBBING.
All trees, stumps, and brush existing on the site of the work, which must be removed for completion of the work, shall be removed. This removal shall be considered part of the contract for the structure. As part of the contract for a structure, the Engineer may order removal of trees and stumps which are near but not on the site of the work, if their presence will interfere with completion of adjacent parts of the improvement of which the structure is a part and if their later removal by usual methods would endanger the structure. Blasting shall not be done within 50 feet (15 m) of any completed part of the structure.

The work and payment for clearing and grubbing shall be in accordance with Section 2101.

2402.03 ELEVATIONS AND DIMENSIONS OF FOOTINGS.
Under normal construction conditions, footings shall be constructed to elevations shown in the contract documents. The Engineer may order, in writing, such changes in dimensions or elevations of footings as may be necessary to secure a satisfactory foundation.

2402.04 TREATMENT OF FOUNDATIONS.
If a footing on rock is specified, the excavation shall be done in a manner to allow the rock to be exposed and prepared in accordance with Article 2405.04. If the footing is to rest on firm earth, special care shall be taken not to disturb the bottom of the excavation. Final finishing of the bottom of the footing excavation, if wet, shall not be done until just before the footing is to be placed.

The Contractor shall control drainage in the foundation area to reduce moisture and mud problems to a practical minimum and shall prepare and maintain the area in an acceptable condition prior to and during placement of concrete. The Engineer may require improved drainage, removal of mud, filling with suitable material, or other procedures to obtain a reasonably suitable condition in the area. This requirement shall not be construed as an order for foundation treatment material or as a basis for extra compensation.

If the foundation material is unsuitable, the Engineer may direct that the foundation be over excavated and backfilled with granular surfacing materials approved by the Engineer. Backfilling shall be performed in accordance with Article 2402.09.

2402.05 CONSTRUCTION OF COFFERDAMS.
Cofferdams shall be constructed in accordance with Article 2405.02.

2402.06 REMOVAL OF COFFERDAMS.
Unless otherwise shown in the contract documents, cofferdams, sheeting and bracing shall be removed by the Contractor.

2402.07 INSPECTION OF EXCAVATION.
After each excavation is completed, the Contractor shall notify the Engineer, who will make an inspection of the depth of excavation and character of foundation material. Concrete shall not be placed until after the Engineer has approved the depth of excavation and character of foundation material. The Contracting Authority will be responsible for delays caused by failure to make inspection within 24 hours after notice has been given the Engineer by the Contractor.

2402.08 REMOVAL OF EXCAVATED MATERIAL.
All material excavated by the Contractor, for bridge and culvert work, that is suitable for backfilling or foreslope construction shall be used for that purpose. Material which is unsuitable because of excessive moisture shall be dried prior to placement.

Unsuitable material shall not be used for either backfilling or in approach fills. Excess material shall be removed from the project in accordance with Article 1104.08.

2402.09 BACKFILLING.
Completed structures shall be backfilled in accordance with the following provisions or in accordance with Section 2506, Flowable Mortar. When flowable mortar or granular backfill is not specified in the contract documents, excavated material shall be used. Backfilling shall continue to natural ground line unless there is inadequate quantities of suitable excavated material. If there is inadequate quantities of suitable excavated material, backfilling shall be continued until the suitable material is depleted.

Material used for backfilling shall be free from organic material, boulders or broken concrete over 8 inches (200 mm) in the greatest dimension, or frozen material.

At the time soil is placed for backfill, its moisture content shall be suitable for compaction. When compaction with moisture control is required by the contract documents, the moisture content in the backfill material shall be increased or reduced, as necessary, to bring the moisture within the designated moisture limits prior to and during placement and compaction.

When granular backfill material is specified, backfill material shall meet requirements of Section 4133. When the volume of material excavated exceeds that of backfill required by the contract documents, the quantity of granular backfill material furnished shall be increased to provide backfill for the excess volume of excavation. Granular backfill shall be constructed in layers of not more than 8 inches (200 mm). Each layer shall be thoroughly tamped or vibrated to insure compaction. The Engineer may require granular material to be moistened with water during backfilling operations.

Except as provided in Article 2403.19, at least 14 calendar days shall elapse after concrete has been placed before backfill is placed against concrete culverts, abutments, piers, arches, wingwalls, or against timber abutments or wingwalls which depend on cast-in-place concrete anchors.

Backfill shall not be placed against timber abutments or wingwalls until all required anchor rods are in place and ready to function. Backfill shall not be placed against any timber abutment or wingwall which is designed to gain support from a superstructure until the superstructure is in place and permanently fastened to the substructure.

Backfill material may be placed in water only when removal of water from the area to be backfilled is impractical, as around piers or abutments located within the waterway or in other deep excavations where removal of cofferdams is required before backfilling, and such removal prevents dewatering. Backfill material placed in water need not be consolidated. When specified, all backfill material placed under water, over which a subsequent embankment is to be placed, shall be granular backfill material.

Backfill material placed above the water line shall be placed in layers not more than 8 inches (200 mm) in loose thickness. Each layer shall be thoroughly compacted before material for the next layer is placed. Except as noted below, all compaction shall be accomplished by rolling with an approved roller or by tamping with a mechanical tamper. Pneumatic tampers shall be operated according to the manufacturer's recommendations.

When moisture control is required by the contract documents, backfill material shall be placed in layers not more than 8 inches (200 mm) in loose thickness. Each layer shall be reasonably leveled and thoroughly compacted before the next layer is placed. A tamping type roller described in Article 2001.05, A, shall be used, and compaction shall be not less than one roller passage per inch (25 mm) of loose thickness. A mechanical tamper described in Article 2001.04 shall be used for each layer in areas inaccessible to the roller. Excavation shall be to a width to accommodate the roller to be used and to provide a reasonably level area for the roller operation for the first and all subsequent layers.

Where backfill is required on both sides of a concrete wall, abutment, or other monolithic structure, filling operations shall proceed simultaneously on both sides of the structure so that the two fills are kept at approximately the same elevation at all times. For the purposes of this paragraph, concrete box, arch, and circular culverts and rigid frame bridges, except wingwalls, shall be considered to be monolithic structures.

Where backfill is to be placed on one side only of retaining walls, or wingwalls of culverts 8 feet (2.5 m) or more in height, rolling shall not be done within 3 feet (1 m) of the wall face. Compaction of the 3 feet (1 m) closest to these walls or wing faces shall be done by pneumatic or hand tampers only.

Within 7 working days after concrete may have been subjected to flexural stresses as provided in Article 2403.19, B, material excavated by the Contractor for construction of concrete culverts shall be removed as provided in Article 2402.08. The Contractor shall prepare the site for placing the adjacent embankment. The time period for removing excavated material may be extended by the Engineer if the extension will not interfere with work of others or the public. For culvert extensions on roads open to traffic, backfilling to the top of the culvert shall be completed within 14 working days after the curing period has expired.

2402.10 EMBANKMENTS ADJACENT TO BRIDGES, CULVERTS, OR STRUCTURES.
When the contract requires construction of an embankment adjacent to a bridge, culvert, or other structure, Article 2107.15 shall apply unless the contract documents require the placement of flowable mortar in accordance with Section 2506.

2402.11 CLASSIFICATION OF EXCAVATION.
All excavation for structures will be classified as Class 20, Class 21, Class 22, Class 23, or Class 24, as defined in this Article.

Class 20 excavation shall include all excavation for bridges above the excavation classification line shown in the contract documents and not classified as Class 22 excavation. Class 20 excavation shall also include all excavation for culverts not classified as Class 22, 23, or 24 excavation. None of the excavation for culverts shall be classified as Class 21 excavation.

Class 21 excavation shall include all excavation for bridges below the excavation classification line shown in the contract documents and not classified as Class 22 excavation.

Class 22 excavation shall include the measured volume of granite, trap, quartzite, chert, limestone, sandstone, hard shale, or slate in natural ledges. It shall also include the estimated or measured volume of rock fragments or boulders having a volume of 1 cubic foot (0.03 m³) or greater.

Class 23 excavation shall include all excavation included in the definitions of Classes 20, 21, and 22 and any other material encountered regardless of its nature, except for removal of old structures or parts of structures.

Class 24 excavation shall include only the additional excavation necessary to provide material for backfills, approach fills, berms, or a roadway over the structure when material resulting from other classes of excavation for the structure is of insufficient quantity or of unsatisfactory quality for these purposes.

2402.12 METHOD OF MEASUREMENT.
The quantities of Class 20, 22, 23, and 24 excavation shall be measured in cubic yards (cubic meters) by the cross section method or other appropriate method. Boulders may be measured after excavation. Class 21 excavation will be computed in cubic yards (cubic meters) within the boundaries specified and from data shown in the contract documents.

When the location of part or all of an old structure scheduled to be removed falls within the planes describing the excavation volume for either structures or culverts (Article 2402.12, A and B), any volume of excavation performed as part of the removal of the old structure, which is above the elevation of the bottom of footings and within the excavation limits described below, will be included in the volumes of excavation measured for payment on the new structure. All other excavation performed in conjunction with removal of old structures will be considered incidental to removal, and additional payment will not be made. Reduction in excavation quantity will not be made for portions of existing structures removed from the excavation limits of new structures.

A. Excavation for Structures.
The quantity of Class 21 excavation measured, unless modified as provided in Article 2402.13, will be the quantity shown in the contract documents. For other classes of excavation, the quantity measured for payment will be that actually removed except as provided in this Article for culverts. However, unless required by the contract documents or ordered by the Engineer, measurement will not be made of material removed outside areas bounded by vertical planes parallel to the boundaries of the structure or part of structure and located as follows:

For concrete structures and parts of structures without footings, 18 inches (0.5 m) outside the horizontal projection of the structure; for concrete structures with footings, 18 inches (0.5 m) outside the footings; for timber abutments and wingwalls, 24 inches (0.6 m) behind the backing plank; for anchor rods, 12 inches (0.3 m) on each side of the rod; for buried anchors, the face of the buried anchor on one side and 24 inches (0.6 m) outside the buried anchor on the other face.

For roadway pipe culverts, the amount of excavation measured for payment will be computed from an excavation centered on the center line of the pipe, to the required depth, length, and a width of 42 inches (1 m) plus the specified diameter of the pipe in inches (millimeters). The vertical plane as described above will be changed to a 1:1 slope from the bottom of the excavation sloping away from the structure. When the 1:1 slope is used, it shall extend the length of the structure unless indicated otherwise in the contract documents. This shall not apply to culvert extensions unless indicated in the contract documents. Modification will not be made in the quantity shown in the contract documents for variations in wall thickness of the pipe. Modification will be made for changes in location or flow line as provided in this section.

For cast-in-place culverts the amount of excavation measured for payment will be computed from an excavation centered on the center line of the culvert, to the required depth, length, and a width 2 feet (0.6 m) greater than the width of the footing. The vertical plane as described above will be changed to a 1:1 slope from the bottom of the excavation sloping away from the structure. When the 1:1 slope is used, it shall extend the length of the structure unless indicated otherwise in the contract documents. This shall not apply to culvert extensions unless indicated in the contract documents. Modification will be made for changes in location or flow line as provided in this section.

When moisture control is required by the contract documents the amount of excavation measured for payment will be computed for an excavation to the required depth and length and a width extending 6 feet (2 m) beyond the limits of the structure.

The Engineer may require a 48 hour notice prior to beginning excavation so necessary measurements of the existing ground may be made. Payment will not be made for any material removed before these measurements are made.

In the case of two or more footings supporting a pier or similar structure which is continuous between footings at any elevation below the excavation classification line, the planes described above shall be located as if the footings were continuous and of the width of the footings to be built.

When the quantity of Class 20 excavation is based on the assumption that prior Class 10 excavation by a grading contractor will be made, the depth of Class 20 excavation, if removed by the bridge contractor, shall be increased by the depth of Class 10 excavation (grading) not completed prior to commencement of the Class 20 excavation, if the Class 10 excavation is not in actual progress or completed by the starting date of the bridge contract. This increase will not apply if the projects involving Class 10 (grading) and Class 20 (bridge) excavation are part of the same contract.

The estimated quantities of excavation are computed from data available when plans are prepared and, unless contract quantities are agreed to, are not to be used as the measured quantity, except for Class 21 excavation and as specified below for culvert excavation.

B. Excavation for Culverts.
When a culvert is built without a change in location, dimensions, or elevation, the quantities of Class 24 and Class 20 or Class 23 excavation as shown in the contract documents shall be the quantity for which payment is made. When the location, width, length, or flow line elevation of a culvert has been changed from that specified in the contract documents, the quantities of excavation shall be measured by the Engineer as indicated above.

C. Embankments.
Construction of embankments adjacent to bridges, culverts, or structures will not be measured for payment, but will be considered incidental to the type of excavation specified. Materials removed from old fills or embankment for the convenience of the Contractor to facilitate use of rolling or hauling equipment will not be measured for payment.

D. Granular Backfill.
The quantity of granular backfill shown in the contract documents shall be the quantity for which payment is made except granular backfill required and furnished for structural concrete placement at bridge abutments will not be measured separately for payment.

E. Foundation Treatment Material.
The quantity of foundation treatment material measured for payment will be computed in cubic yards (cubic meters) by the Engineer from measurements of the space to be excavated and backfilled, or it may be measured in the transporting vehicle or weighed. Foundation treatment material not ordered placed by the Engineer or quantities in excess of the quantity ordered placed by the Engineer will not be measured for payment. When weighing is accepted as the method of measurement and the material is weighed prior to delivery, the cubic yards (cubic meters) will be determined by the method outlined in Article 2312.08, A.

F. Compaction with Moisture Control (Structures).
Compaction with moisture control (structures) will be the number of cubic yards (cubic meters) of backfill or embankment, or both, placed with moisture control, as required, regardless of the class of excavation.

G. Flowable Mortar.
When flowable mortar is specified in the contract documents, it shall be measured as specified in Section 2506.

2402.13 BASIS OF PAYMENT.
The quantities of Class 20, Class 21, Class 22, Class 23, and Class 24 excavation, measured as provided above, will be paid for at the contract unit prices per cubic yard (cubic meter) except as provided in the following Paragraphs A, B, C, and D:

A. Extra Depth Excavation for Structures Other than Culverts.
Upon written order of the Engineer, the Contractor shall excavate for footings to depths below those shown in the contract documents. When the extra depth of excavation does not exceed 6 feet (1.8 m), payment will be made for extra depth at the following percentages of the contract unit price for the excavation to the footing elevation shown in the contract documents.

Depth	Excavation Above Classification Line	Excavation Below Classification Line
First foot (0 to 0.30 m) Second foot (0.31m to 0.60 m) Third foot (0.61 m to 0.90 m) Fourth foot (0.91 m to 1.20 m) Fifth foot (1.21 m to 1.50 m) Sixth foot (1.51 m to 1.80 m)	100% 120% 130% 140% 150% 160%	100% 140% 160% 180% 200% 220%
NOTE: If the bridge plans fail to show an excavation line, low water elevation as shown in the contract documents shall be considered as the excavation classification line for the above purpose.

When the extra depth excavation exceeds 6 feet (1.8 m), all excavation below the elevation of the bottom of the footing, as shown in the contract documents, will be paid for as extra work as provided in Article 1109.03, B.

When the extra depth excavation necessitates removal and reconstruction of a cofferdam which complied fully with requirements of Article 2405.02, the cost of removal of the old cofferdam and construction of the new one will be paid for as extra work as provided in Article 1109.03, B.

B. Excavation for Changes in Horizontal Dimensions of Footings.
On written order of the Engineer, the Contractor shall construct footings having horizontal dimensions other than those shown in the contract documents. When such a change necessitates removal and reconstruction of a cofferdam which complied fully with the requirements of Article 2405.02, the cost of removal of the old cofferdam and construction of the new ones shall be paid for as extra work as provided in Article 1109.03, B. Payment for excavation will be made at the same unit prices as if there had been no change in dimensions of the footings.

C. Overhaul.
Material from classes of excavation other than Class 24 will ordinarily be deposited within 200 feet (60 m) from the point of excavation as directed by the Engineer. Overhaul beyond the free haul limit of 200 feet (60 m) will be paid for as extra work as provided in Article 1109.03, B.

Overhaul will be paid on Class 24 excavation as provided in Section 2108, except the free haul limit will be 500 feet (150 m).

D. Unexpected Rock Excavation.
When the contract documents provide unit prices for Class 20 and Class 21 excavation but does not provide a price for Class 22 excavation, any material required to be excavated which conforms to the definitions for Class 22 excavation shall be paid for at 3.5 times the contract unit price for the class of excavation in which it is encountered, subject to the provisions for extra depth as provided in Paragraph A.

When the contract provides a unit price for Class 23 excavation only, payment will not be made for unexpected rock.

E. Foundation Treatment Material.
Foundation treatment material furnished according to Article 2402.04 shall be paid for at the Contractor's unit delivered cost per cubic yard (cubic meter) plus the applicable contract unit price for the class of excavation treated but not to exceed $25 per cubic yard ($33 per cubic meter) for the combined cost of excavation and treatment.

F. Granular Backfill.
Payment for granular backfill will be at the contract unit price per cubic yard or ton (cubic meter or megagram). The cost of granular backfill required and furnished for structural concrete placement at bridge abutments shall be included in the contract unit price for the structural concrete.

G. Compaction with Moisture Control (Structures).
For the quantity of backfill or embankment, or both, placed with moisture control, the Contractor will be paid the contract unit price per cubic yard (cubic meter).

H. Flowable Mortar.
When flowable mortar is specified in the contract documents, payment will be as provided in Section 2506.