209Structure Excavation

209.01 Description

Structure excavation is excavating bridge foundations and all other structure foundations. The item includes disposing of excess or unsuitable material from the excavations, backfilling to the original ground level, bailing, pumping, draining, sheeting, shoring, and cribs.

209.01.1 Structure Excavation Type I

Structure excavation Type I is excavating, de-watering, shoring, and cribbing, backfill and compaction for the excavation.

209.01.2 Structure Excavation Type II

Structure excavation Type II is excavating, de-watering, backfill, and compaction for the excavation, excluding shoring and cribbing.

209.01.3 Shoring and Cribs

This is constructing and removing all shoring and cribs, cofferdams, or caissons, and for all material, labor, equipment, tools, and incidentals to complete the work.

209.02 Reserved

209.03 Construction Requirements

209.03.1 General

The plan excavation lines in the contract are estimated. Excavate all foundations to the plan elevations and dimensions. Removing boulders, logs, and other obstructions found in the excavation is incidental to this work. Remove timber, sheeting, and other material used in the excavation before backfilling. Remove and stockpile all excavated material that is suitable for backfill.

209.03.2 Treatment of Foundation Materials

When the excavation reaches the designated depth, de-water, clean, and maintain the excavation until the foundation bed is inspected. Clean and fill rock seams and crevices with concrete mortar. Obtain the Project Manager’s approval of the foundation before placing concrete on the foundation. Place concrete without disturbing the bottom of the excavation. Minimize disturbance of the natural ground outside the excavation pay limits except as required for constructing cofferdams.

209.03.3 Cofferdams

Submit drawings and calculations prepared by a professional engineer showing the proposed method of cofferdam construction and de-watering procedures before starting the work. The cofferdam must meet OSHA requirements. Ensure cofferdams or cribs for foundation construction are watertight to permit de-watering. Provide clearance within the cofferdam for constructing forms, inspection of the form exteriors, and for pumping. Re-align or enlarge the cofferdams or cribs that are tilted or moved laterally during the work to provide work clearance at Contractor expense. 209 – STRUCTURE EXCAVATION 2020 EDITION V5.1 209-2 Timber bracing may be left in cofferdams or cribs extending into the substructure masonry with the Project Manager’s written approval. When weighted cribs are used to resist the hydrostatic pressure acting against the bottom of the foundation seal, use an anchorage to transfer the entire weight of the crib to the foundation seal. When the foundation seal is placed, vent or port the cofferdam at the cofferdam design low- water level. The foundation seal depths in the contract are based on the estimated, normal water-surface elevations or are consistent with those satisfactorily used on past projects. The specified seal thickness is a minimum. The Contractor may request an increased seal depth. Submit the request in writing. Any approved increase in seal depth and associated costs are at Contractor expense. Repair or replace failed cofferdams, foundation seals or both at Contractor expense. Pump out the cofferdam and place the remaining masonry or concrete in the dry after meeting the time limit in Subsection 209.03.4 . Remove all cofferdam or crib material after the substructure is complete without disturbing or marring the finished work.

209.03.4 Pumping Water from Cofferdams

Pump interior foundation enclosures without disturbing the in-place concrete. Do not pump for at least 24 hours after placing concrete unless pumping from a sump separated from the concrete work by a watertight wall.

209.03.5 Inspection

Place the footings as soon as practical after the excavation depth and the foundation material are approved. Drill holes or drive rods in the excavation bottom to determine the materials quality when requested by the Project Manager. Excavate the spread footings and take rod soundings at each individual substructure unit and submit rod soundings simultaneously for the footing elevation approval.

209.03.6 Backfilling

Once approved, backfill and compact all excavated areas without damaging adjacent structures, to match the existing ground line. Place backfill to be covered by roadway embankment in maximum 8-inch (200 mm) loose thickness, continuous horizontal layers. Compact each layer in accordance with Subsection 203.03.3 . Remove and dispose of backfill containing large or frozen lumps, wood, or other deleterious materials. Do not jet or pond the backfill. Serrate or step the slope bounding the excavation for abutments and wingwalls. Place coarse gravel or broken stone around drain holes in wingwalls or abutments as shown in the contract. Backfill around piers and in front of abutments and wingwalls with material large enough to resist erosion. If acceptable material is not available, the Project Manager may order stone or lean concrete backfill, paid for as extra work. Place backfill against masonry abutments, and wingwalls in accordance with Subsection

203.03 2(B)

. Allow culvert related concrete work to cure 14 calendar days before backfilling. 2020 EDITION V5.1 STRUCTURE EXCAVATION – 209 209-3 Dispose of excess material at Contractor expense, in accordance with all applicable laws, rules and regulations.

209.04 Method of Measurement

209.04.1 Structure Excavation Type I and Type II

Measurement in cubic yards (m3) is based on the volume bounded on the sides by vertical planes 18 inches (455 mm) outside of the footing neat lines; on the top by the original undisturbed ground surface at the time excavation begins or by the lines in the contract; and on the bottom to the specified footing elevation or the elevation directed by the Project Manager. Calculations for tie beams, overhangs, or similar volumes extending beyond the footing lines are computed from lines 18 inches (455 mm) outside of and below neat lines. The computed structure excavation includes only those portions not contained in the volume of footing excavation.

209.04.2 Shoring and Cribs

Shoring and cribs used with structure excavation Type I are not measured for payment. Shoring and cribs used with structure excavation Type II are measured by the lump sum.

209.05 Basis of Payment

Payment for the completed and accepted quantities is made under the following: Pay Item Pay Unit Shoring and Cribs Lump Sum Structure Excavation Type I Cubic Yard (m3) Structure Excavation Type II Cubic Yard (m3) Additional approved material for backfill provided from other sources is paid for as extra work. Payment includes the costs of obtaining the material, processing, handling, and transporting to the project. The cost of placing and compacting the additional material and disposing of unsuitable material is included in the contact unit price for structure excavation. No payment is made for additional material placed outside structure excavation pay limits and slope lines to comply with safety regulations. No payment is made for additional material to replace material removed from the excavation, rendered unsuitable by improper excavation, handling, or stockpiling methods. Partial payments for structure excavation Type I or II will be made based on the total quantity as follows:

Structure Excavation in other states

• Connecticut 2.03 · Structure Excavation
• Indiana 206 · STRUCTURE EXCAVATION
• New Hampshire 206 · STRUCTURE EXCAVATION
• Nevada 206 · Structure Excavation
• South Dakota 420 · STRUCTURE EXCAVATION
• Virginia 401 · Structure Excavation
• Washington 2-09 · Structure Excavation