Art. 501.07 Excavation for Structures Removal of existing pipe culvert concrete headwalls will be paid for at the contract unit price per each for CONCRETE HEADWALL REMOVAL. Removal of existing pipe culverts will be paid for at the contract unit price per foot (meter) for PIPE CULVERT REMOVAL. When a pay item is provided in the contract, removal of existing slope wall will be paid for at the contract unit price per square yard (square meter) for SLOPE WALL REMOVAL. When a pay item is provided in the contract, removal of existing bridge rail will be paid for at the contract unit price per foot (meter) for BRIDGE RAIL REMOVAL. When the Engineer directs that earth and debris be removed from culvert inverts, such removal will be paid for according to Article 109.04. When existing structures or portions of existing structures are encountered which cannot be removed by normal excavation procedures and are not shown on the plans or are not evident in the field and are required to be removed, the cost of such removal will be paid for according to Article 109.04. Rock excavation will be paid for according to Article 502.13. SECTION 502. EXCAVATION FOR STRUCTURES
502.01 Description. This work shall consist of the excavation required for the
construction of structures including bailing, draining, pumping, sheeting; the construction of cofferdams, or temporary cribs if found necessary, and their subsequent removal; and backfilling to the level of the ground surface as it existed before any excavation was made. CONSTRUCTION REQUIREMENTS
502.02 Clearing, Tree Removal, and Protection of Existing Plant Material.
Prior to starting excavation operations in any area, all clearing, tree removal, and protection of existing plant material in that area shall be performed as specified in Section 201.
502.03 General. Excavation for structures shall include all materials
encountered, regardless of their nature. Structure excavation shall include all excavation, except rock excavation or excavation within a cofferdam. Cofferdam excavation shall include all excavation within the limits of a cofferdam, except rock excavation. Rock excavation for structures shall consist of the excavation of boulders 1/2 cu yd (0.4 cu m) in volume or greater and all rock in ledges, bedded deposits, and conglomerate deposits exhibiting the physical characteristics and difficulty of rock Excavation for Structures Art. 502.06 removal as determined by the Engineer. After the Engineer has made the determination that the material qualifies as rock excavation, the Contractor may use any method, approved by the Engineer, to remove the rock. Rock excavation for structures shall also include existing concrete, masonry, timber grillages, foundation piles, and similar materials which are not exposed to view, are not shown on the plans, and for which payment is not otherwise provided.
502.04 Sequence of Operations. The elevations of the bottoms of footings,
as shown on the plans, shall be considered as approximate and the Engineer may order such changes in dimensions or elevations of footings as may be necessary to secure a satisfactory foundation. Where foundation piles are used, the excavation of each footing, as shown on the plans, shall be completed before the piles are driven. After the piles are driven, all loose and displaced material shall be removed to the bottom of the footing elevation.
502.05 Excavation in Rock. Footings shall be excavated to the dimension
shown on the plans and no rock shall project inside of such dimension more than 2 in. (50 mm). Other rock excavation shall be as necessary for the construction of the structure, subject to the limitations for measurement for payment specified in
Article 502 — 12. All cracks, voids, seams, or other irregularities in the excavation shall
be cleaned and filled with concrete.
502.06 Cofferdams. A cofferdam will be defined as a temporary structure,
consisting of engineered components, designed to isolate the work area from water to enable construction under dry conditions based on either the Estimated Water Surface Elevation (EWSE) or Cofferdam Design Water Elevation (CDWE) shown on the plans and as specified herein. When cofferdams are not specified on the plans and conditions are encountered where the excavation for the structure cannot be kept free of water for prosecuting the work by pumping and/or diverting water, the Contractor, with the written permission of the Engineer, will be permitted to construct a cofferdam. The Contractor shall submit a cofferdam plan for each cofferdam to the Engineer for approval prior to the start of construction. Cofferdams shall not be installed or removed without the Engineer's approval. Work shall not be performed in flowing water, except for the installation and removal of the cofferdam. The cofferdam plan shall address the following:
a.Cofferdam (Type 1). The Contractor shall submit a cofferdam plan which addresses the proposed methods of construction and removal, the construction sequence including staging, dewatering methods, erosion and sediment control measures, disposal of excavated material, effluent water control measures, backfilling, and the best management practices to prevent reintroduction of excavated material into the aquatic environment. The design and method of construction shall provide, within the measurement limits specified in Article 502.12, necessary clearance for forms, inspection of exterior of the forms, pumping, and protection of fresh concrete from water. For Type 1 cofferdams, it is anticipated the design will be based on the EWSE shown on the plans.
b.Cofferdam (Type 2). In addition to the requirements of Article 502.06(a), the Contractor’s submittal shall include detailed drawings and design Art. 502.07 Excavation for Structures calculations, prepared and sealed by an Illinois Licensed Structural Engineer. For Type 2 cofferdams, it is anticipated the design will be based on the CDWE shown on the plans.
c.Seal Coat. The seal coat concrete, when shown on the plans, is based on design assumptions in order to establish an estimated quantity. When seal coat is required, it shall be considered an integral part of the overall cofferdam system and, therefore, its design shall be included in the overall cofferdam design submittal. If a seal coat was not specified but determined to be necessary, it shall be added to the contract by written permission of the Engineer. The seal coat concrete shall be constructed according to
Article 503 — 14. After the excavation within the cofferdam has been
completed and the piles have been driven (if applicable), and prior to placing the seal coat, the elevation of the bottom of the proposed seal coat shall be verified by soundings. The equipment and methods used to conduct the soundings shall meet the approval of the Engineer. Any material within the cofferdam above the approved bottom of the seal coat elevation shall be removed. No component of the cofferdam shall extend into the substructure concrete or remain in place without written permission of the Engineer. Removal shall be according to the previously approved procedure.
502.07 Excavation Other Than Rock. When the structure excavation occurs
in material other than rock, the limits of the excavation shall not exceed the dimensions specified in Article 502.12. These limits may be exceeded only with the permission of the Engineer and subject to the limitations for measurement for payment specified in Article 502.12. The depth of the excavation shall be carried to the plan bottom of the footing elevation. If the material encountered at the plan bottom elevation of spread footings is soft, muddy, or otherwise unsuitable, the material shall be removed to an additional depth as directed by the Engineer and replaced with crushed stone, gravel or other material approved by the Engineer.
502.08 Pumping. Pumping from the interior of a foundation enclosure shall
be done in a manner approved by the Engineer. Pumping will not be allowed during placement of the concrete or for a period of 24 hours after completion of the placement, unless the pumping is accomplished from a watertight sump separated from the concrete being placed. Pumping to dewater a sealed cofferdam shall not begin until the seal coat has attained the design strength.
502.09 Inspection. After each excavation is completed, the Contractor shall
notify the Engineer. No concrete shall be placed until after the Engineer has approved the depth of the excavation and the character and condition of the foundation material. When ordered in writing by the Engineer, the bottom of the excavated space within any cofferdam in which a seal coat is to be constructed shall be inspected by a qualified diver.
502.10 Backfilling. Backfilling shall consist of placing and compacting the
necessary fill within the space excavated for a structure below the ground surface as it existed before any excavation was made. Fill required above the ground surface as it existed prior to excavation for the structure shall be considered as embankment. Bracing, forms, and rubbish shall be removed from the excavation before the backfill Excavation for Structures Art. 502.10 is placed. Unless sheeting is to remain in place, it shall be removed at such time as directed by the Engineer to prevent loosening unexcavated material and facilitate placing and compacting the backfill. Sloping sides of the excavation shall be stepped or serrated to prevent wedging action of the backfill against the structure. Where the original ground surface is higher than the proposed elevation of roadway surface, stream banks or channels, the backfill shall be constructed up to the elevation designated as the proposed ground surface. Backfill which is to serve as a roadbed, or upon which embankment is to be placed, shall be constructed by materials satisfactory to the Engineer. No sod, frozen material, or any material which, by decay or otherwise, might cause settlement, shall be placed or allowed to remain in the backfill at such locations. Whenever the material obtained from the excavation is suitable, it may be used in constructing the backfill. Excavated material that is unsuitable for backfill because it is in excess of 110 percent of the optimum moisture content shall be allowed to dry before being used as backfill. Excavated material unsuitable for backfill shall be disposed of according to Article 502.11. If the amount of suitable excavated material is insufficient, suitable material shall be obtained and used for making or completing the backfill. In placing backfill or embankment, the material shall be placed simultaneously insofar as possible to approximately the same elevation on both sides of a wall, pier, or column. If conditions require placing backfill or embankment appreciably higher on one side of a wall, pier, or column than on the opposite side, the additional material on the higher side shall not be placed until test specimens show that the concrete has attained the required flexural strength and the curing period is completed. In the absence of tests to determine the flexural strength, the additional material on the higher side shall not be placed until at least 14 days have elapsed after the placing of the concrete, exclusive of days on which the temperature of the air surrounding the concrete falls below 45 °F (7 °C). Backfill or embankment shall not be placed behind the walls of concrete culverts until the top slab is placed and cured. Backfill and embankment behind the sidewalls of culverts having a clear height of more than 5 ft (1.5 m), shall be carried up simultaneously, and at no time shall the fill be more than 2 ft (600 mm) higher than behind the opposite sidewall. Backfill shall not be placed in water at closed abutments, culverts, or retaining walls. The excavated area around these structures shall be pumped dry, and any mud or loose material within the excavated area shall be removed before placing backfill. At piers, backfill may be placed in water, providing no roadway embankment or slope wall is to be supported by the backfill and provided that both the water level and backfill are kept at approximately the same elevation on opposite sides of the pier. A time interval, approved by the Engineer, shall elapse before placing additional fill on one side of the pier, above the water surface. Mechanical compaction of backfill will not be required around piers upon which no roadway embankment, slope wall, or other highway appurtenance is to be placed; and at those locations that are not adjacent to a highway, railroad, or other improvement beneath the structure. Art. 502.10 Excavation for Structures Except as specified, the procedures for placing and compacting the backfill shall be according to Articles 205.04, 205.05, and 205.06. Except as described above, all backfill shall be placed in continuous horizontal layers not more than 8 in. (200 mm) in thickness, loose measurement, and each layer shall be compacted with a mechanical tamper of a type approved by the Engineer before the next layer is placed, and the backfill shall be compacted to the density specified in Article 205.06. If the moisture content of the backfill material exceeds 110 percent of the optimum moisture content determined for this material, no additional material shall be placed without the permission of the Engineer. When drain holes are present in abutments, wingwalls, retaining walls, or culverts, a 24 in. (600 mm) wide x 48 in. (1.2 m) tall strip of geocomposite wall drain material, according to Article 1040.07, shall be placed on the soil side of each drain hole. The strip shall be horizontally centered over the drain hole with the bottom located 12 in. (300 mm) below the bottom of the drain hole.
502.11 Disposal of Excess Excavation and Unsuitable Material.
Unsuitable material and suitable material in excess of that required for backfilling shall be disposed of according to Article 202.03.
502.12 Method of Measurement. This work will be measured for payment as
follows.
a.Contract Quantities. The requirements for the use of contract quantities shall conform to Article 202.07(a).
b.Measured Quantities. Structure excavation, when specified, will be measured for payment in its original position and the volume computed in cubic yards (cubic meters). Horizontal dimensions will not extend beyond vertical planes 2 ft (600 mm) outside of the edges of footings of bridges and walls. The vertical dimension for structure excavation will be the average depth from the surface of the material to be excavated to the bottom of the footing as shown on the plans or ordered in writing by the Engineer. The volume of any unstable and/or unsuitable material removed within the structure excavation will be measured for payment in cubic yards (cubic meters). Rock excavation for structures will be measured for payment as follows.
1.General. Rock excavation will be measured for payment in its original position and the volume in cubic yards (cubic meters) computed by the method of average end areas.
2.Footings and Seal Coats. Rock excavation for footings and seal coats will be measured for payment in its original position and the volume computed in cubic yards (cubic meters). Measurements will be taken vertically from the top of the rock to the elevation of the bottom of the rock or bottom of the structure, whichever occurs first, and horizontally within the perimeter of the structure to be placed.
3.Pipe Structures. Rock excavation for pipe structures will be measured for payment in its original position and the volume computed in cubic Excavation for Structures Art. 502.13 yards (cubic meters). Measurements will be taken vertically from the elevation of the top of the rock to the specified elevation below the bottom of the pipe and horizontally for the width of the trench specified for placing the pipe. When the depth of rock removal below the bottom of a pipe structure is not otherwise specified, the rock shall be removed to 8 in. (200 mm) below the bottom of the pipe; except for water service lines and pipe underdrains, the depth of removal shall be 3 in. (75 mm) below the bottom of the pipe. Rock excavation for storm sewers which are jacked in place will be measured as the volume actually moved, except that the horizontal dimension will not be greater than the external diameter of the pipe plus 12 in. (300 mm) and the vertical dimension will not be greater than the external diameter of the pipe plus 12 in. (300 mm) above the pipe and 8 in. (200 mm) below the pipe, unless the total vertical dimension is less than 4 ft (1.2 m), in which case 4 ft (1.2 m) may be used.
4.Boulders, Concrete, or Timber. Boulders, concrete, or timber, 1/2 cu yd (0.4 cu m) or more in volume, will be measured for payment individually and the volume in cubic yards (cubic meters) computed from average dimensions taken in three directions. The quantity of concrete or timber to be paid for will be the volume of such material actually removed within the limits of the excavation as specified.
5.Sumps in Rock. Where it is necessary to construct sumps in rock, measurements shall include the areas and depths required for such sumps. Cofferdam excavation will be measured for payment in cubic yards (cubic meters) in its original position within the cofferdam. The horizontal dimensions used in computing the volume will not extend beyond vertical planes 2 ft (600 mm) outside of the edges of the substructure footings or 4 ft (1.2 m) outside of the faces of the substructure stem wall, whichever is greater. The vertical dimensions will be the average depth from the surface of the material to be excavated to the elevation shown on the plans for bottom of the footing, stem wall, or seal coat, or as otherwise determined by the Engineer as the bottom of the excavation.
502.13 Basis of Payment. Except as provided, the work specified in this
Section will not be paid for as a separate item. Where excavation for structures is not specified, the cost of the excavation shall be considered as included in the contract unit price for the class of concrete involved, or other unit price item of the work for which it is required. Structure excavation, when specified, will be paid for at the contract unit price per cubic yard (cubic meter) for STRUCTURE EXCAVATION. Cofferdam excavation will be paid for at the contract unit price per cubic yard (cubic meter) for COFFERDAM EXCAVATION. When the contract does not contain a pay item for cofferdam excavation and this item is required, it will be paid for according to Article 109.04. Rock excavation for structures will be paid for at the contract unit price per cubic yard (cubic meter) for ROCK EXCAVATION FOR STRUCTURES. When the contract Art. 503.01 Concrete Structures does not contain a pay item for rock excavation for structures and this item is required, it will be paid for according to Article 109.04. Removal and disposal of unstable and/or unsuitable material will be paid for at the contract unit price per cubic yard (cubic meter) for REMOVAL AND DISPOSAL OF UNSUITABLE MATERIAL FOR STRUCTURES. When the contract does not contain a pay item for removal and disposal of unstable and/or unsuitable material for structures and this item is required, it will be paid for according to Article 109.04. Where it is necessary to excavate below the plan bottom of footing elevation, the excavation will be paid for at the contract unit prices for the class of excavation involved. Furnishing and placing the crushed stone, gravel, or other material will be paid for according to Article 109.04. Cofferdams, when specified, will be paid for at the contract unit price per each for COFFERDAM (TYPE 1) or COFFERDAM (TYPE 2), at the locations specified. When added to the contract, cofferdams will be paid for according to Article 109.04. Tree removal and protection of existing plant material will be paid for according to Section 201. Additional suitable material required for backfilling within the roadbed, will be paid for according to Article 109.04. When ordered by the Engineer in writing, cofferdam inspection by a certified diver will be paid for according to Article 109.04. SECTION 503. CONCRETE STRUCTURES
503.01 Description. This work shall consist of constructing cast-in-place
concrete structures.
503.02 Materials. Materials shall be according to the following.
Item Article/Section
a.Portland Cement Concrete ..................................................................... 1020
b.Protective Coat ....................................................................................... 1023
c.Preformed Expansion Joint Fillers .......................................................... 1051
d.Waterproofing Materials ..................................................... 1060.01 - 1060.08
e.Nonmetallic Water Seals ........................................................................ 1054
f.Reinforcement Bars .................................................................................. 508
g.Grout .................................................................................................. 1024.01
h.Metal Hardware Cast into Concrete .................................................... 1006.13
503.03 Equipment. Equipment shall be according to the following.
Item Article/Section
a.Hand Vibrator ................................................................................ 1103.17(a)
b.Vibrating Screed ....................................................................... 1103.17(g)(1)
c.Finishing Machine ........................................................................... 1103.13(a)
d.Fogging Equipment ......................................................................... 1103.17(k)
e.Underwater Concrete Placement Equipment ..................................... 1103.18
Referenced in this section
EXCAVATION FOR STRUCTURES in other states
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 321–327 of 1,217. View official source ↗