STRUCTURAL EXCAVATION AND BACKFILLING SECTION 207 118 SECTION 207 — STRUCTURAL EXCAVATION AND BACKFILLING
207.1Description.
This work consists of excavation and backfilling for placement of structures and pipes.
207.2Material.
Borrow Section 209 and Section 1001
207.3Construction.
A.Structural and Pipe Excavation.
1.Handle excavated material in accordance with Section 202.3. Dispose of unsuitable material and
other obstructions in accordance with Section 106.8.
2.Remove unsuitable material below the foundation elevation as directed by the engineer, as
extra depth excavation.
a.The type of backfill material below the foundation elevation will be as directed by the
engineer.
3.The engineer will inspect the footing area after excavation is complete. Place concrete or
precast units after the engineer approves the stability of the foundation material.
B.Shoring.
1.Provide shoring in accordance with Section 604.3. 6, Section 604.3. 7, and when required by
OSHA standards.
2.Remove temporary shoring and bracing upon completion of the work, unless otherwise noted in
the contract.
C.Rock Excavation for Structures and Pipe Trenches.
1.The Department will consider all material the contractor cannot excavate without blasting or
using rippers, and all boulders and detached stones with a volume of 1/3 cubic yard or greater, as rock excavation. The classification "Rock Excavation" shall n ot apply to soft disintegrated rock, bituminous pavements, gravel, broken stone, or concrete pavements. These and other materials are classified as normal excavation and are included under Section 202.3.3. Drain pockets left in the surface of the rocks bef ore backfilling.
2.Excavate material classified as rock as follows:
a.For structures, a width of 24 -inches outside of the neat line and a depth of 12 -inches below
the subgrade.
b.For pipe trenches, a width of 18 -inches from each side of the outside wall of the pipe and a
depth of 12 -inches below the pipe invert.
3.Complete required blasting in accordance with Section 202.3.10.C .
D.Backfilling
1.Backfilling is placing materials as defined in the contract above the bedding material and below
the subgrade of the pavement structure or the ground elevation. STRUCTURAL EXCAVATION AND BACKFILLING SECTION 207 119 2. Place and compact borrow in accordance with Section 202.3.8 and the following:
a.Place and spread backfill material in uniform horizontal lifts no greater than 8 inches loose
measurement. Compact to 95 percent or more of the maximum density before placing the next lift. Submit requests to increase lift thickness to the engineer for approval. Maintain proper moisture content to achieve the required density.
b.Compact backfill material without causing damage or applying excessive pressure against
structures. Place fill adjacent to the end bent of a bridge only to the bottom of the backwall until the superstructure is in place. Place backfill on each side of t he structural unit simultaneously to proposed grades so that compaction does not create unbalanced stresses on the structure.
c.When backfilling over structures, use heavy mechanical compacting equipment only after
placing a minimum of 24 -inches of cover over the structural unit or in accordance with the structure manufacturer’s recommendations.
207.4Method of Measurement.
A.Structural and Pipe Excavation
1.The Department will measure excavation in cubic yards of material excavated within the
payment limits as follows:
a.Excavation volume is limited by vertical planes located 24 -inches outside of the neat line
perimeter of the vertical faces of the structural element and 18 -inches outside of the pipe.
b.The upper limit as the lowest combination of the following :
i.The existing ground surface ;
ii. the bottom of roadway excavation ; iii. the bottom of channel excavation ; and iv. excavation incidental to removal of structures and obstructions.
c.The lower limit as the bottom of the pipe bedding or as the bottom of the structural
foundation as shown on the plans.
d.Place pipes in fill in accordance with Section 601.3.2.
2.The Department will not measure excavation of material outside the payment limits as defined
above, unless the engineer directed excavation beyond the specified limits.
3.The Department will measure extra depth excavation in linear feet below the bottom of the pipe
bedding or structural foundation as shown on the plans.
B.Temporary Shoring and Bracing
1.The Department will not measure temporary shoring or bracing.
C.Rock Excavation for Structures and Pipe Trenches
1.The Department will measure the quantity of rock excavation for structures and pipe trenches in
cubic yards. STRUCTURAL EXCAVATION AND BACKFILLING SECTION 207 120 a. The Department will measure the volume of rock excavation to the limits of excavation required by the contract or as adjusted by the engineer based on exposing the rock to perform cross -sections before and after excavation.
b.The Department will not measure rock excavated from depths in excess of 12 -inches below
the pipe invert or bottom of footing .
D.Providing Structural Backfill
1.Providing of structural backfill will be measured in cubic yards. Backfill will not exceed 1.3 times
the volume determined by the backfilling template.
E.Structural and Pipe Backfilling
1.The Department will measure backfilling in cubic yards of material backfilled within the payment
limits as follows :
a.defined in 207.4.A.1.a, less the volume of any structures or pipes.
b.The upper limit will be finished grades minus depth of riprap or pavement.
c.The lower limit will be a combination of the top surface of the foundation stabilization or
bedding and the top surface of structures or pipes.
207.5Basis of Payment.
A.The Department will pay the quantity of:
1.Structural and pipe excavation at the contract unit price per cubic yard. Price and payment
constitute full compensation for:
a.Excavating, hauling, storage, stockpiling and reuse, and disposing of excavated materials;
b.placing and removing shoring or bracing;
c.material excavated or backfilled outside of the payment limits;
d.temporary shoring and bracing left in place
e.removing existing pipe within the excavation template ; and
f.dewatering .
2.Rock excavation for structure and pipe trench rock excavation at the contract unit price per
cubic yard. Price and payment will constitute full compensation for:
a.Drilling, blasting, and presplitting;
b.excavating, removing rock, and placing and compacting backfill materials within the template
area;
c.hauling and disposing of surplus material;
d.draining pockets in the surface of the rock; and
e.removing shattered or loosened material and replacing it with approved backfill material.
3.Providing structural backfill in accordance with section 209 at the contract unit price per cubic
yard. No payment will be made for backfill material generated under Section 207 . STRUCTURAL EXCAVATION AND BACKFILLING SECTION 207 121 4. Structural and pipe backfilling at the contract unit price per cubic yard. The Department will consider that price and payment as constituting full compensation for placing and compacting all approved backfill.
B.The Department will not pay for rock excavation that is more than 12 -inches below the pipe
invert. The Department will not pay for backfill or backfilling areas between the over excavated subgrade and 12 -inches below the proposed pipe invert.
C.When the engineer requires extra depth excavation beyond the prescribed limits, the Department
will pay the unit price plus the additional percentage according to the pay limits provided in Table 207.5 -1 below. Table 207 .5 -1. Payment for Additional Excavation Depth Depth Lowered Additional Percent More Than (feet) Not Over (feet) 0 5 25 5 8 60 8 10 100
ITEM DESCRIPTION UNIT 207001 PIPE, CULVERT AND STRUCTURE BACKFILLING CY 207002 PIPE, CULVERT AND STRUCTURE EXCAVATION CY 207010 ROCK EXCAVATION FOR STRUCTURES AND TRENCHES CY 207011 ROCK EXCAVATION FOR STRUCTURES AND TRENCHES (FIXED PRICE) CY 20702 0 STRUCTURAL BACKFILL, BORROW TYPE B, PROVIDING ONLY CY 20702 1 STRUCTURAL BACKFILL, BORROW TYPE C, PROVIDING ONLY CY
Source: Delaware Standard Specifications for Road and Bridge Construction, 2025 Edition. Pages 128–131 of 779.