4-4 (c) Equipment type and locations of equipment on the structure(s) or adjacent
roadways during the removal operations.
d.Locations and type of work to be performed directly adjacent to traffic.
e.Temporary bracing or supports to be used.
f.Details and locations of protective covers and other measures to ensure that people, property and improvements will not be endangered or damaged as a result of the removal operations. This shall include methods for protecting any pavement surfaces including shoulders , concrete barriers and other highway features.
g.Proposed methods of removal or containment of loose debris from structures with traffic to be open below.
h.Propos ed methods of access and containment methods of debris and slurry from removal of bridges over w ater. Acceptance of the demolition plan does not relieve the Contractor of the responsibility and liability to safe ly and satisfactorily demolish the structure .
402-3 Measurem Ent and Payment
The price and payment below will be full compensation for demolition plans and all items required to remove existing structures including , but not limited to, those items contained in
Article 402 — 1.
When the contract includes the item of Removal of Existing Structure at Station ____, the work of removing the structure will be paid at the contract lump sum price for this item. When the contract includes the item of Removal of Existing Structures at Station ____, the work of removing the structures will be paid at the contract lump sum price for this item. Payment will be made under: Pay Item Pay Unit Removal of Existing Structure at Sta tion ____ Lump Sum Removal of Existing Structures at Sta tion ____ Lump Sum
410-1 Description
Excavate any material as necessary for the construction of foundations and end bent caps for bridges, retaining walls of reinforced concrete or reinforced masonry, arch culverts and box culverts without floor slabs in accordance with the contract or as directed by the Engineer . Excavate, perform exploratory drilling at footings to a depth not to exceed 5 f eet, blast, drain , divert water, bail and pump. Provide and remove bracing, shoring, sheeting, cribbing and cofferdams; substructure scour protection, subsurface drainage and drawings; and backfill including hauling and dispos al of materials. Do not deposit excavated materials or construct earth dikes or other temporary earth structures in rivers, streams or impoundment or so near to such waters that they are carried into any river, stream or impoundment by stream flow or surface runoff. As an exception to the above, obtain written approval for the use of confined earth materials in coffer dams for structure foundations.
4-5 410-2 Materials
Refer to Division 10. Item Section Subsurface Drainage Materials 1044
410-3 Foundation Excavation
Notify the Engineer a sufficient time before beginning the excavation to allow measureme nts of the undisturbed ground. Where necessary for safety, slope, shore, brace or protect by cofferdams the foundation openings in accordance with State and local safety standards. Perform foundation excavation and related work in such sequence that no portion of the s tructure is endangered by subsequent operations. Adequately protect completed portions of a structure during blasting operations. Consider the dimensions and elevations of footings, as shown in the plan s as approximate only. The Engineer may order, in writing, such changes in dimensions or elevations of footings as necessary to secure a satisfactory foundation. Notify the Engineer after excavating each foundation. Do not place concrete before obtaining approval for the excavation depth, the character of the foundation and permission to proceed. Perform drilling as may be required by the Engineer to obtain information as to the depth to which the rock or other hard foundation material extends below the bottom of the footing. Clean all rock or other hard foundation material of all loose material and cut to a firm surface, either level, stepped or serrated, as directed by the Engineer . Clean out all seams and fill with concrete, mortar or grout. Remove all loose and disintegrated rock and thin strata. L eave the rock surface in a rough condition to form an adequate key against lateral movement of the footing. When the footing rests on an excavated surface other than rock, take special care not to disturb the bottom of the excavation until immediately befo re placing reinforcing steel and concrete. Remove foundation material softened and weakened by exposure and inundation down to sound, solid material before placing steel and concrete. When using piles or drilled piers , complete the excavation of each pit before installing piles or piers . When water or other unsuitable material is encountered, pile driving liquefies the soil, or the bed is otherwise unsuitable as determined by the Engineer, remove the material as required and backfill to the required elevat ion with subdrain fine or coarse aggregate . Such work will be paid as extra work in accordance with Article 104 -7.
410-4 Cofferdams
A.General The term cofferdam designates any temporary or removable structure constructed to hold the surrounding earth, water or both, out of the excavation. It includes timber cribs, any type of sheet piling, removable steel shells or similar structures, all neces sary bracing and the use of pumping wells or well points for the same purpose. Ensure cofferdams located in bodies of water are designed, detailed and sealed by a n engineer licensed by the State of North Carolina when the distance from the water surface t o the bottom of the excavation is 5 f eet or greater.
4-6 (B) Construction
Design and construct cofferdams to adequate depths and heights, safely and as watertight as is necessary for the proper performance of the work. Provide interior dimensions of cofferdams as to give sufficient clearance for the construction and inspection of forms and to permit pumping outside the forms. Provide at least 5 feet of clearance between the proposed edge of footing and inside face of cofferdam when a keyed footing is required and at least 3 feet when a keyed footing is not required. Right, rest or enlarge cofferdams that are tilted or moved laterally during the process of sinking to provide the necessary clearance. Construct cofferdams to protect plastic concrete against damage f rom a sudden rising of the stream and to prevent damage to the foundation by erosion. Do not leave timber or bracing in cofferdams that could extend into the substructure concrete without permission from the Engineer .
C.Removal After the completion of the s ubstructure, unless otherwise provided in the contract, remove cofferdams with all sheeting and bracing to the streambed or one foot below existing ground. Take care not to disturb or damage the finished concrete.
410-5 Pumping
Perform pumping operations in accordance with Article 414 -5.
410-6 Preservation of Channel
Unless otherwise required by the contract or permitted by the Engineer, do not excavate in stream channels outside of cofferdams. Do not disturb the natural streambed adjacent to the structure without permission. Backfill any excavation or dredging made at the site of the structure outside of the cofferdam limits to the original ground surface or streambed with approved material. Remove materials placed within the stream area and leave the stream in its original condition, unless otherwise permit ted by the Engineer .
410-7 Utilization of Excavated Material
Use suitable excavated material as backfill. Use suitable material that is not required for backfill to form embankments, subgrades or shoulders. Furnish disposal areas for excavated unsuitable materials and suitable materials not required in connection with other work included in the contract. Do not place excavated material in a stream or other body of water or wetland. Do not deposit excavated material at any time so as to endanger the partly finished structure, either by direct pressure , indirectly by overloading banks adjacent to the operations or in any other manner.
410-8 Backfilling and Filling
Use approved material for backfill that is free from large or frozen lumps, wood or other undesirable material. Where there is not an adequate quantity of suitable backfill material available from the excavation, provide suitable backfill material com pensated in accordance with A rticle 410 -10. Refill all excavated spaces , not filled with permanent work, with earth up to the ground surface existing before the excavation. Place backfill to provide adequate drainage as soon as concrete surfaces are finished in accordance with Subarticle 420 -17(B) and the concrete has been inspected and approved by the Engineer . The Engineer has the authority to suspend all operations until such backfilling is acceptably completed. Eliminate any slope adjacent to the excavation for abutments, wingwalls and retaining walls by stepping or serrating to prevent wedge action.
4-7 Place and compact all portions of the backfill that become a part of roadway typical sections or
their foundations in accordance with Subarticle s 235-3(B) and 235- 3(C). Place all other portions of the backfill in layers not more than 10 inches in depth of loose measure and compact to a density comparable to the adjacent undisturbe d material. Place backfill or embankment material simultaneously to approximately the same elevation on both sides of an abutment, pier or wall. If conditions require placing backfill or embankment higher on one side, do not place the additional material on the higher side until the concrete develops the minimum specified strength for the class of concrete required for the structure as specified in Table 100 0-1. Do not place backfill or embankment behind abutments of rigid frame structures such as arch culverts and box culverts without floor slabs, until the top slab is placed and has developed the minimum compressive strength of the class of concrete required for the structure . Place backfill and embankment simultaneously behind opposite abutments of rigi d frames. Place backfill to not cause excess lateral forces against the structure by heavy equipment or from earth masses transmitting pressures caused by earth moving equipment. Place backfill immediately adjacent to the structure by hand operated mechan ical tampers. Do not operate heavy earth moving equipment within 10 feet of the structure in backfilling operations.
410-9 Blasting Adjacent To Highway Structures
Conduct blas ting operations adjacent to highway structures in accordance with the following requirements. Submit a blasting plan for approval by the Engineer before conducting any blasting operation. Do not conduct blasting operations within 60 feet of any structure until the concrete strength reaches 2 ,400 psi. After the concrete achieves a strength of 2 ,400 psi, limit the maximum PPV to 4 in/sec measured at the closest structure extremity. For multi- column bents with column heights up to 40 feet and a combined span length for the 2 adjacent spans of 160 feet or less, adhere to the following criteria:
A.Do not blast within 6 feet without obtaining prior written approval.
B.At distance of 6 feet to 10 feet, do not use a quantity of explosives more than 0.5 lbs. per delay period.
C.From 11 feet to 60 feet, use a maximum charge weight per delay of 0.5 lb. and 0.5 lb. of explosives per foot of distance over 10 feet. No vibration measurements are required if the above criteria are met. If unable to meet the above criteria, monitor the structure for vibrations . If the 4 in/sec limit is exceeded, the Engineer will evaluate each subsequent blast, and if deemed necessary, will apply more restrictive controls than those above to prevent damage.
410-10 Measurement and Payment
The prices and payments below will be full compensation for all items required to complete foundation excavation, including but not limited to those items listed in Article 410-1. Payment of blasting operations is included in the bid price for Foundation Excavation at the affected substructure unit.
4-8 (A) Foundation Excavation on a Cubic Yard Basis
When the contract calls for payment of Foundation Excavation on a cubic yard basis, it will be measured and paid as the actual number of cubic yards of materials, measured in their original position within the limits described below and computed by the ave rage end area method, that are acceptably excavated. The upper limits for measurement are the actual ground surface at the time of starting work, except where the excavation is performed in cut areas excavated under Section 225, the upper limits are the ro adway plan typical section. For keyed footings the upper limits of the keyed section are as shown in the plan s. Define a “ keyed footing” as a footing placed without forms for the keyed depth in an excavation whose sides, as near as practical, are located at the neat line dimensions of the footing and are vertical. When the foundation material is other than rock, the lower limits for measurement are the elevation of the bottom of footing as established by the plans or as directed by the Engineer . When the foundation material is rock, the lower limits for measurement are the actual rock elevations after the foundation is approved. As an exception to the lower limits established above, when in the opinion of the Engineer excess excavation is performed due to carelessness or negligence on the part of the Contractor, the Engineer notifies the Contractor of that portion of the excavation whic h is not measured for payment. Horizontal limits for measurement are established by vertical planes located 18 inches outside of the neat line dimensions of the footing as established by the plans or directed in writing by the Engineer. For keyed footings the horizontal limits for measurement of the keyed section are established by vertical planes located at the neat line di mensions of the footing as established by the plans or directed in writing by the Engineer . Measurement includes mud, muck or similar semi -solid material within the limits described above provided such material is present at the time excavation begins and cannot be drained away or pumped without the use of a jet or nozzle.
1.No measurement is made of the following excavation, as such excavation is incidental to the work being performed:
a.Excavation necessary to construct end bent caps and the berm adjacent to the cap.
b.Excavation necessary to construct pile encasement.
c.Excavation outside of the limits described in this subarticle.
d.Excavation necessary from heaving of a foundation due to the driving of piles.
e.Excavation necessary from overbreaks or slides.
f.Mud, m uck or similar semi- solid material which can be drained away or pumped without the use of a jet or nozzle.
g.Excavation made before the Engineer makes measurements of the undisturbed ground.
h.Excavation necessary due to exposure or inundation allowed by the C ontractor or negligence on the part of the Contractor.
4-9 (2) Foundation Excavation will be paid at the contract unit price per cubic yard for
Foundation Excavation except where the Engineer directs the Contractor in writing to excavate below the original plan el evation of the bottom of the footing. P ayment for such excavation will be made as follows:
a.For excavation made below the original plan elevation of the bottom of the footing to an elevation 3 feet below such plan elevation, payment will be made at the contract unit price per cubic yard for Foundation Excavation.
b.For excavation made below an elevation 3 feet below the original plan elevation of the bottom of the footing but not more than 6 feet below such plan elevation, payment will be made at 150 % of the contract unit price per cubic yard for Foundation Excavation .
c.For excavation made below an elevation 6 feet below the original plan elevation of the bottom of the footing, payment will be made as extra work in accordance with Article 104 -7.
d.In areas where piles have been driven, removal of material and backfilling with subdrain fine or coarse aggregate in accordance with Article 410 -3 will be paid as extra work in accordance with Article 104 -7.
B.Foundation Excavation on a Lump Sum Basis When the contract calls for payment of Foundation Excavation on a lump sum basis, no measurement will be made of any foundation excavation made at such locations.
1.When the contract calls for payment on a lump sum basis, payment will be made at the contract lump sum price for Foundation Excavation for Bent No. ____ at Station ____ or Foundation Excavation for End Bent No. _ ___ at Station ____ except as otherwise provided below.
2.Where the Engineer directs the Contractor to excavate below the original plan elevation of the bottom of the footing by a distance which is less than 3 feet the character of the work will not be considered to be materially changed and no additional compensation will be allowed for the foundation excavation at such location.
3.Where the Engineer directs the Contractor in writing to excavate more than 3 feet below the original plan elevation of the bottom of the footing, payment for such excavation will be made as extra work in accordance with Article 104 -7.
C.Furnishing and Hauling Backfill Material Where it is necessary to provide backfill material from sources other than excavated areas or borrow sources used in connection with other work in the contract, payment for furnishing and hauling such backfill material will be paid as extra work in accordance with
Article 104 — 7. Placing and compacting such backfill material is not extra work but is
incidental to the work being performed. When the Contractor has been directed by the Engineer to drill in the vicinity of a footing to obtain subsurface information, such drilling in excess of a 5 foot depth will be paid as extra work in accordance with Article 104 -7. When so used, no additional payment will be made for use of the material under other pay items or for stockpiling the material for use under other pay items. Payment will be made under: Pay Item Pay Unit Foundation Excavation Cubic Yard Foundation Excavation for Bent No . ____ at Station ____ Lump Sum Foundation Excavation for End Bent No. ____ at Station ____ Lump Sum
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 140–145 of 857.