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Electrical (16000-16999)

606047 DRILLED SHAFT IN ROCK, 66” DIAMETER LF

DE · 2025 Standard SpecificationsBook pages 233–236View official source ↗

EARTH RETAINING WALL SYSTEMS SECTION 607 223 SECTION 607 — EARTH RETAINING WALL SYSTEMS

607.1Description.

This work consists of designing, fabricating, providing, and placing MSE walls and modular block retaining walls.

607.2Materials.

A.Modular Block Walls Section 1040

B.MSE Walls Section 1048

607.3Construction.

607.3.1 Submittals.

A.Design the wall system in accordance with the specified edition of DelDOT’s Bridge Design Manual

and the specified edition of the AASHTO LRFD Bridge Design Specifications. The engineer will take responsibility for external stability. The wall system des igner shall take responsibility for all other limit states in the design for the selected wall system.

B.Provide design calculations and a complete set of working drawings, in accordance with Section

105.4, before beginning fabrication. Have a registered State of Delaware professional engineer seal the calculations and drawings and obtain the engineer’s ap proval before fabrication. Include the following information in the submittal:

1.Earthwork requirements, including specifications for material and compaction of backfill.

2.Details of revisions or additions to drainage systems or other facilities required to accommodate

the system.

3.Details of barriers or railings connected to the wall.

4.Existing ground elevations, stations, and offsets verified by the contractor for each location

involving construction wholly or partially in original ground or at locations specified in the contract.

5.Complete design calculations substantiating that proposed designs satisfy the design parameters

in the contract.

6.Complete details of all elements required for proper construction of the retaining wall system,

including complete material specifications.

7.Complete list of materials.

8.For modular block walls, include the following:

a.Length, location, and type of wall.

b.Step -by-step process for constructing the wall.

9.Provide the engineer with a certificate of compliance certifying that the provided materials

comply with the applicable contract specifications. Provide the engineer with a copy of all test results performed by the contractor or his supplier necessary t o assure contract compliance. EARTH RETAINING WALL SYSTEMS SECTION 607 224 607.3.2 Excavation and Backfill.

A.Excavate to the elevations shown in the contract in accordance with Section 207. Ensure the work

area remains dry in accordance with Section 906.

B.Grade the foundation level for a width equal to or exceeding the length of the reinforcing strips or

as required for the retaining wall system.

C.Compact the foundation as outlined in the contract before wall construction. Remove and replace

any foundation soils found unsuitable, as directed by the engineer.

D.Simultaneously construct the surrounding earth embankment and compact in lifts at the same

elevation as the MSE wall backfill placement, meeting density requirements in accordance with the contract. 607.3.3 Leveling pad.

A.At each panel foundation level, provide an unreinforced concrete leveling pad as shown in the

contract. Cure the leveling pad a minimum of 12 -hours with materials in accordance with Section 1022.6 before placement of wall panels. The concrete finish will contain a smooth and flat surface, and not vary from the design elevation, as shown in the contract.

B.For modular block walls, construct the foundation element with either a leveling pad or footer, in

accordance with the manufacturer’s instructions. 607.3.4 Wall erection.

A.Place precast concrete panels, constructed in accordance with Section 1048. Handle panels with

lifting devices set into the upper edge of the panels and place in successive horizontal lifts in the sequence shown on the working drawings as backfill placement proceeds. When placing backfill material behind the panels, maintain the panels in vertical position by means of temporary wooden wedges placed in the joint at the junction of the 2 adjacent panels on the external side of the wall. Use external bracin g for the initial lift.

B.Meet the following tolerances:

1.Do not exceed vertical plumb tolerances and horizontal alignment tolerances of more than 3/4 -

inch when measured along a 10 -foot straight edge.

2.The maximum allowable offset between precast components is 3/4 -inch.

3.Do not exceed the overall vertical plumb tolerance from top to bottom of 1/2 -inch per 10 -feet

of wall height.

4.Use horizontal and vertical joint widths between precast components of not less than 1/2 -inch

or more than 1 1/4 - inches.

C.Place geotextile fabric and adhesive on the fill face of the panels over each horizontal and vertical

joint. Ensure that the fabric extends a minimum of 9 -inches onto each panel.

D.Install reinforcing mesh or strips after completing backfill compaction for the respective layer of

soil. Place reinforcing mesh or strips perpendicular to the wall, unless otherwise shown in the contract or as directed by the engineer.

E.Grout recesses at lifting devices in tops of topmost panels flush with an approved mortar , except

where the design calls for a poured concrete coping or parapet.

F.For modular block walls, construct the wall in accordance with the manufacturer’s instructions.

EARTH RETAINING WALL SYSTEMS SECTION 607 225 607.3.5 Backfill Placement.

A.Place backfill to closely follow erection of each course of panels. Place No. 57 stone for at least the

first 3 -feet perpendicular to the back face of the panel for the full height of the wall.

B.Compact backfill to 95 percent of the maximum density as determined by AASHTO T99 Method C

or D, with oversize correction, as outlined in note 7, AASHTO T99.

C.Ensure uniform distribution of the moisture content of the backfill material before and during

compaction throughout each layer. Remove backfill material with moisture content outside the acceptable range and rework until the moisture content is uniformly acceptable throughout the entire lift. Determine the optimum moisture content in accordance with AASHTO T99 Method C or D (with oversize correction, as outlined in note 7, AASHTO T99).

D.The maximum compacted lift thickness is 8 inches. Decrease this lift thickness, if necessary, to

obtain the specified density.

E.Achieve compaction within 3 -feet of the back face of the wall facing using a lightweight

mechanical tamper or hand tamp. Do not use a vibratory system within this area.

F.At the end of each day's operation, slope the last level of backfill away from the back of the wall to

rapidly direct runoff of rainwater away from the wall. In addition, do not allow surface runoff from adjacent areas to enter the wall construction sit e.

G.For modular block walls, place and compact the backfill material in accordance with the

manufacturer’s instructions.

607.4Method of Measurement.

A.The Department will measure the quantity of MSE walls as the number of square feet of wall

placed and accepted. The Department will take the vertical measurement from the top of the leveling pad to the bottom of the coping.

B.The Department will not measure MSE walls for projects with multiple walls of varying height and

material.

C.The Department will measure the quantity of architectural segmental retaining walls and concrete

masonry unit modular block retaining walls as the number of square feet of wall placed and accepted. The Department will take the vertical measurement from the top of the leveling pad or footer.

607.5Basis of Payment.

A.Price and payment for mechanically stabilized earth walls constitute full compensation for

providing the design, providing and placing all materials including backfill , and performing all work required in accordance with the contract and approved design.

B.Price and payment for modular block walls constitutes full compensation for providing the design,

providing all materials, and performing all work required to construct the wall system as specified.

C.The Department will pay for rock excavation in accordance with Section 202.

ITEM DESCRIPTION UNIT 607000 MECHANICALLY STABILIZED EARTH WALLS SF EARTH RETAINING WALL SYSTEMS SECTION 607 226 ITEM DESCRIPTION UNIT 607001 MECHANICALLY STABILIZED EARTH WALLS LS 607011 ARCHITECTURAL SEGMENTAL RETAINING WALLS SF 607012 CONCRETE MASONRY UNIT MODULAR BLOCK RETAINING WALLS SF

Source: Delaware Standard Specifications for Road and Bridge Construction, 2025 Edition. Pages 233–236 of 779.

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