WATERWAY CONSTRUCTION PRACTICES SECTION 909 604 SECTION 909 — WATERWAY CONSTRUCTION PRACTICES
909.1Description.
This work consists of constructing, maintaining, and removing temporary waterway diversions to allow work in existing waterway channels.
909.2Material.
A.Sandbag Dike and Diversion.
1.Borrow Section 1001
2.Sheeting, 6 -mil Section 1022 .6.B
3.Pipe Culvert Section 1031
4.Pre-fabricated sandbag
a.Jute, woven polyester, or polypropylene mesh resistant to ultra -violet radiation.
b.Minimum sack size approximately 16 -inches by 25 -inches measured inside the seam when the
sack is when empty.
B.Geotextile Lined Channel Diversion
1.Stone, Delaware No. 3 Section 1004
2.Geotextile Section 1060
3.Fasteners
Steel pins, 3/16 -inch diameter, minimum 18 -inches long.
4.Washers
Steel, 1 1/2 -inch diameter.
C.Turbidity Curtain
1.Curtain
a.Synthetic material coated with suitable elastomeric or polymeric compound having a high
resistance to weathering, ultraviolet light, hydrocarbons, fresh and saltwater, and temperature extremes.
b.Tensile strength greater than 200 -pounds when measured lengthwise or crosswise.
c.Seams vulcanized welded or sewn with to the full strength of the material.
2.Flotation Units
a.Flexible, buoyant to support the required width of the turbidity barrier.
b.Maintaining freeboard at least 3 -inches above the water surface level.
c.Contained in a flotation sleeve or collar attached to the turbidity curtain.
3.Load Lines
a.Fabricate into the top and bottom of the turbidity curtain.
WATERWAY CONSTRUCTION PRACTICES SECTION 909 605 b. Top load line consisting of woven webbing or vinyl sheathed steel cable, with a minimum breaking strength of 10,000 -pounds.
c.Bottom consisting of 5/16 -inch minimum galvanized steel chain in bottom hem of the turbidity
curtain.
d.With devices that develop the full breaking strength for connecting to load lines in adjacent
sections.
4.Shoreline Stakes
Anchor the turbidity curtain in place.
5.Fasteners
a.5/8-inch long brass or copper staples; or
b.17-gage galvanized or aluminized steel tie wires
6.Anchors
a.Standard marine type boat anchors.
b.Danforth type anchors for sandy bottoms.
c.Kedge or mushroom type anchors for mud bottoms.
d.Alternate anchoring methods, heavy concrete, weights, or driven pilings.
7.Rope
a.Polypropylene, 5/8 -inch diameter.
b.Breaking strength 800 -pounds.
D.Stream Diversion.
1.Sandbags
2.Geotextile Section 1060
3.Steel sheet piles Section 1032
4.Stone Section 1004
E.Stilling Well.
1.Riprap, R -4 Section 1006
2.Geotextile Section 1060
909.3Construction.
A.Inspect weekly and immediately after every rainfall to maintain and make repairs as needed.
B.General Excavation
1.Excavate in a continuous and uninterrupted operation.
2.Stockpile excavated material outside the 100 -year floodplain and temporarily stabilize in
accordance with Section 908.
C.Sandbag Dike or Diversion
WATERWAY CONSTRUCTION PRACTICES SECTION 909 606 1. Construction
a.Construct sandbag dikes or diversions in accordance the Standard Construction Details. Begin
at the upstream end of the channel and proceed downstream.
b.Overlap sheeting by covering the downstream portion with the upstream portion. Overlap at
least 24 -inches.
c.Construct a weir in the sandbag dike in accordance with the project plans.
2.Maintenance
Repair or replace to maintain an acceptable work environment.
3.Removal
a.Remove the dike or diversion upon completion of all work with the approval of the engineer.
b.Regrade the area to match the contours shown in the contract or match the grades that
existed before construction if the contract does not show contours.
c.Stabilize all areas affected by the sandbag dike or diversion in accordance with Section 908.
D.Geotextile Lined Channel Diversion
1.Construction
a.Replicate in size and shape the cross -section of the natural channel, unless otherwise
specified.
b.Excavate from downstream to upstream.
c.Excavate under dry conditions, including the downstream and upstream connection to the
natural channel.
d.Use sandbags to contain the stream.
e.Install geotextile as shown on the Standard Construction Details.
2.Maintenance
a.Inspect at the beginning and end of each day to ensure proper function.
b.Make repairs immediately.
3.Removal
a.Redirect stream flow to its natural path and remove the geotextile lined channel.
b.Remove all materials related to the geotextile lined channel and backfill the area in
accordance with Section 207.3.D.
c.Regrade the area to match the contours shown in the contract or match the grades that
existed before constructing the channel diversion if the contract does not show contours.
d.Stabilize areas affected by the construction of the geotextile lined channel diversion in
accordance with Section 908.
E.Floating Turbidity Curtain
1.Construction
WATERWAY CONSTRUCTION PRACTICES SECTION 909 607 a. Submit the manufacturer’s drawings and technical specifications to the engineer before installing the turbidity curtain and its accessories.
b.Assemble and install a turbidity curtain in accordance with the manufacturer’s directions.
c.Install the turbidity curtain parallel to the flow of water along the riverbank. Do not install the
turbidity curtain perpendicular to the direction of stream flow. Perform construction activities generating any sediment or turbidity within the turbidit y curtain.
d.Begin installing at high tide from a shoreline anchorage and work along with the current in a
downstream direction.
e.Form a continuous vertical and horizontal barrier to suspended sediment. Rest the bottom of
the turbidity curtain in contact with the bottom of the waterway for the entire length of the turbidity curtain.
f.Float the turbidity curtain into position, attached to the anchor lines, and then unfurl. Attach
curtain panel ends together using rope lashings. Tie the top lashing to the anchor line. Place the anchors so the turbidity curtain remains in the plan location and the current does not pull the flotation devices under the water. If directed by the engineer, supply and place additional anchorage.
g.Fasten the curtain to the side of the stakes facing the work area generating the sediment and
turbidity.
2.Maintenance
a.Maintain the turbidity curtain throughout the project construction period so that no sediment
caused by the project enters the waterway.
b.Repair or replace all turbidity curtains damaged before installation, during installation, or
during the life of the contract, to the satisfaction of the engineer.
3.Removal
a.Do not remove the turbidity curtain until completing the work in accordance with the
contract. Minimize impacts to adjacent waters and other areas when removing turbidity curtains and related components. Upon removal, the turbidity curtains and related components become the contractor’s property.
F.Stream Diversion
1.Construction
a.Dewater in accordance with Section 906.
b.Implement the contract design within the limits shown in the contract without additional
impacts to the stream or wetland depicted on the environmental compliance sheet.
c.For additional impacts, submit a preliminary layout of the impacts to the engineer. Obtain
written permission before proceeding with final design.
d.Comply with all applicable hydrologic and hydraulic engineering standards in effect when
preparing a proposed alternative stream diversion plan regarding system capacity and potential surface water impacts, upstream and downstream of the stream diversio n. WATERWAY CONSTRUCTION PRACTICES SECTION 909 608 e. Upon obtaining permission to proceed with the final design of a proposal for an alternate stream diversion, prepare and submit the alternate in accordance with Section 105.4. Submit 3 copies of the final design and provide the following:
i.Detail demonstrating the adequacy of the materials, methods, and equipment in providing
stream diversion and erosion and sediment control; ii. an itemized list of all materials and equipment; iii. scaled drawings of the proposal overlaid on the environmental compliance sheet in the plans; iv. supporting computations;
v.all necessary supporting paperwork required for the submission of the permit modification
request to the appropriate permitting agency; and vi. a table of any increased temporary impacts to wetlands and open waters.
f.Provide a signature and seal on the plans from a professional engineer in the State of
Delaware.
g.The Department’s Environmental Studies Office will make application for permit modifications
through the appropriate permitting authorities.
h.The Department will not guarantee the approval of any proposed alternative plan by any
permitting authority or the Department. Denial of the alternate plan, long review times, or multiple submissions to any or all permitting authorities to gain approval does not relieve the contractor from its obligation to complete the project on time. The time between submission of the final status of the permit modification and response from the engineer may take as long as 2-months. The Department will not grant addi tional contract time for delays resulting from failing to schedule enough time for permit modification review and final decision.
i.Obtain the engineer’s approval for installing and testing the approved stream diversion system
before disturbing the existing structure.
2.Maintenance
Maintain each component in accordance with the contract.
3.Removal
Remove each component in accordance with the contract.
G.Stilling Well
1.Construction
a.Install to the dimensions shown in the contract or a minimum of 5 -feet by 5 -feet. Temporarily
stockpile all channel bed material from the excavated area. When overlapping the sheeting, the upstream portion will cover the downstream portion, and overlap at least 24 -inches.
b.Line all surfaces of the stilling well with the geotextile before placing the riprap. Place the
geotextile and riprap as indicated on the plans, Standard Construction Details, and Section 707.
2.Maintenance
WATERWAY CONSTRUCTION PRACTICES SECTION 909 609 Maintain to the original dimensions and function throughout project construction. Remove and dispose of all trash and debris that enters the stilling well and interferes with the well function.
3.Removal
a.Remove upon completion of all work, with the approval of the engineer.
b.Regrade the area to match the contours shown in the contract or match the grades that
existed before constructing the stilling well if the plans do not show contours.
c.Stabilize all areas affected by the construction of the stilling well in accordance with Section
908.
909.4Method of Measurement.
A.The Department will consider sediment removal as incidental to maintenance of the work. The
Department will measure the quantity of work acceptably completed for waterway construction as follows:
1.Sandbag dike or diversion by the number of cubic feet of sandbags placed and accepted with 1
sandbag equaling 1 -cubic foot.
2.Geotextile lined channel diversion by the number of cubic yards excavated and accepted.
3.Floating turbidity curtain by the number of linear feet of turbidity curtain placed and accepted
measured from edge to edge along the support cable.
4.Stilling well by the number of cubic yards excavated and accepted.
5.The Department will not measure stream diversion.
909.5Basis of Payment.
A.The Department will pay the quantity of sandbag dikes and sandbag diversions at the contract unit
price per cubic foot. Price and payment constitute full compensation for:
1.Providing and placing all materials;
2.constructing;
3.maintaining;
4.temporary stabilization;
5.removing and disposing;
6.restoring the area; and
7.permanent stabilization.
B.The Department will pay the quantity of geotextile lined channel diversion at the contract unit
price per cubic yard. Price and payment constitute full compensation for:
1.Excavating;
2.providing and placing all material;
3.maintaining;
4.temporary stabilization;
WATERWAY CONSTRUCTION PRACTICES SECTION 909 610 5. removing;
6.restoring the site; and
7.permanent stabilization.
C.The Department will pay the quantity of floating turbidity curtain at the contract unit price per
linear foot. Price and payment constitute full compensation for:
1.Assembling;
2.installing;
3.maintaining; and
4.removing the turbidity curtain.
D.The Department will pay the quantity of stream diversion at the contract lump sum price. Price
and payment constitute full compensation for:
1.Providing and placing all materials:
2.excavation and installation;
3.maintenance;
4.removal;
5.restoration;
6.design and preparation of plan submittals;
7.supporting paperwork and copies; and
8.permit acquisition costs.
9.The Department will consider the cost associated with repairing or replacing the stream
diversion as included in the lump sum bid price and will make no separate payment for this work.
10.The Department will pay the for damage resulting from an overtopping event, including cleaning
and rebuilding of the stream diversion system, under the force account provisions of these specifications. The Department will not pay for any stream diversi on materials placed before the engineer’s approval.
11.The Department will consider materials used for the stream diversion system as the contractor’s
property after removal.
12.The Department will pay for dewatering the work area in accordance with Section 90 6.
E.The Department will pay the quantity of stilling well at the contract unit price per cubic yard. Price
and payment constitute full compensation for:
1.Providing all materials;
2.excavating, backfill, and backfilling;
3.maintaining;
4.temporary stabilization;
5.removal;
WATERWAY CONSTRUCTION PRACTICES SECTION 909 611 6. restoring the site;
7.backfilling; and
8.permanent stabilization.
ITEM DESCRIPTION UNIT 909001 SANDBAG DIKE CF 909002 SANDBAG DIVERSION CF 909003 GEOTEXTILE LINED CHANNEL DIVERSION CY 909004 TURBIDITY CURTAIN, FLOATING LF 909005 STREAM DIVERSION LS 909006 STILLING WELL CY
STORMWATER MANAGEMENT FACILITIES SECTION 910 612 SECTION 910 — STORMWATER MANAGEMENT FACILITIES
910.1Description.
This work consists of constructing stormwater management facilities.
910.2Materials.
A.Infiltration Stone (No. 3, No. 8, or No. 57) Section 1004
1.Washed, free of stone dust, fines, or soil particles
2.Maximum of 2 percent passing #200 sieve when tested in accordance with AASHTO T11.
3.Do not use crushed concrete or recycled asphalt pavement (RAP)
4.Geotextile Section 1060
B.Clay Borrow
1.Borrow Sources Section 209.3.1
2.Borrow Source Testing Section 209.3.2
3.Cut-Off Trench, Clay Borrow, Type 2 Section 1002.1
4.Pond Liner, Clay Borrow Type 1 Section 1002.1
C.Outlet Structure, Concrete
1.Borrow Section 209 and Section 1001
2.Concrete
a.Riser structures - precast or cast in place.
b.Cast -in-place concrete - walls, anti -seep collars, and principle spillway bedding.
c.PCC, Class A Section 1022
i.Foundations, riser structures, retaining and weir walls, principle spillway pipe bedding , and
anti-seep collars .
3.Reinforcing Steel, Grade 60 Section 1037
4.Liquid Membrane -Forming Compounds for Curing Section 1045.7
5.Non-Shrink Grout Section 1047.2
6.Pipe, principal spillway Section 1031
7.Steps AASHTO M199 and ASTM C478
8.Trash Rack – Aluminum
9.Riprap Section 1060
10.Turf Reinforcement Matting Section 908
D.Stormwater Management Pond
1.Liner or cut -off trench material Sections 910.2B, 209, 908, 1001
Source: Delaware Standard Specifications for Road and Bridge Construction, 2025 Edition. Pages 614–622 of 779.