Industry Day No. 1 - Stilling Basin Modification.pdf

KEYSTONE DAM STILLING

BASIN MODIFICATION

Industry Day No. 1 November 2025

WELCOME

Agenda

1. Meeting Purpose

2. Introductions

3. Contractor Involvement

4. Acquisition Strategy – Industry Days and IDaC

5. Project Overview

6. Proposed Modifications

7. Potential Work Sequencing

8. Construction Considerations

9. Contractor Follow-up Questions

*This presentation is for general information and will not change the terms and conditions of any subsequent solicitation or contract

*This is part of our market research, to be used for preliminary planning purposes. THIS IS NOT A SOLICITATION FOR PROPOSALS AND NO CONTRACT WILL BE AWARDED FROM THIS PRESENTATION. No reimbursement will be made for any costs associated with providing information in response to this presentation or any follow up information requests.

MEETING PURPOSE

• Provide a general introduction to the Keystone Dam Safety Modification Project

• Socialize this project with industry

• Provide a project overview to interested contractors

• Gage contractor interest in Early Contractor Involvement (ECI) using an Integrated Design and Construction (IDaC) contract

• Gain insight on how contractors would approach access to the site

INTRODUCTIONS

CONTRACTOR INVOLVEMENT

USACE, TULSA DISTRICT CONTRACTING

Contractor Involvement

• This event does not constitute a solicitation

• Meeting is intended to provide market research for interested contractors

• All information presented is tentative and subject to change

• Hold all questions until the end of the presentation

• Planned future contractor engagements:

• Onsite Contractor Site Visit (November 18, 2025)

• Contractor 1 on 1 meetings

• Future Industry Days TBD

• In accordance with FAR 36 / DFARS 236, the estimated magnitude of construction for the total project is over $500,000,000

• Industry day attendee lists will be posted to SAM.gov as soon as possible

WHY ARE WE HAVING INDUSTRY DAYS

• USACE is considering engagement of private industry during Preconstruction Engineering and Design

(PED) Phase through an Integrated Design and Construction – Early Contractor Involvement (IDaC-ECI) contracting vehicle.

• The primary reason that IDaC is being considered is:

• Utilizing an IDaC-ECI delivery method will help to plan for and manage flood risk during construction and life safety risk. Contractors can provide valuable input into how construction will be completed within certain constraints. Working to satisfy our principle of Do No Harm (ER 1110-2-1156).

• IDaC also provides opportunity to:

• Reduce uncertainties related to some design and means/method components of the project.

• Create efficiencies within the construction schedule, which is constrained due spring rains and required spillway releases.

ACQUISITION STRATEGY – INDUSTRY DAYS AND IDAC

INTEGRATED DESIGN AND CONSTRUCTION

• Integrated Design and Construction (IDaC) is a construction contracting method to maximize integration, collaboration, and partnering between the designer of record and construction contractor during the design phase and subsequently through construction completion.

• IDaC is a simplification of the more complex version of Early Contractor Involvement (ECI) – FAR 52.216-17 (Fixed Price Incentive Successive Targets). The IDaC methodology is tailored for construction with a pre-construction services base award with a construction option established at award. The IDaC Request for Proposal (RFP) will include a maximum price for the construction option (Ceiling Price).

• The Government awards a contract to a construction contractor (i.e., IDaC contractor) prior to the completion of the design documents.

• IDaC permits award of the construction contract early in a project’s development through a competitive process. The Government retains the IDaC contractor during design to collaborate with the designer of record ( USACE is the designer of record for this project) to provide pre-construction phase services through innovation resulting in risk reduction.

• By sharing risk with the construction contractor, it results in less risk to contractors and stakeholders while financially incentivizing the contractor to collaborate with the team to meet cost objectives.

BRIEF INTRODUCTION TO IDAC

INTEGRATED DESIGN AND CONSTRUCTION

• This early involvement enables the construction contractor (i.e., IDaC contractor) to provide constructability and cost input as the design progresses to the Designer of Record (i.e., architect-engineer contractor, or in-house staff)

• USACE is the Designer of Record for the Keystone Dam Safety Modification Project

*Government is Designer of Record

PROJECT BENEFITS OF IDAC

• Educates and vests the contractor in the paramount life safety risk objective during the design phase

• Provides collaboration on a preferred construction sequence that achieves the contractor’s objective to construct the project as efficiently as possible but within the context of do no harm before construction starts avoiding conflicts and delays during construction

• Inform on design topics such as concrete overlay and stilling basin modification design, anchors design, dewatering and other civil design considerations

• Validates the construction schedule and cost estimate

• Improves contractor limitations (i.e., access, sequencing, restrictions) through design considerations and achieves “buy-in” up front regarding work restrictions

PROJECT OVERVIEW

• Keystone Dam is multi-purpose project providing flood risk management, water supply, hydroelectric power, navigation, fish and wildlife, and recreation benefits. The project is operated for optimum flood risk management in the Arkansas River Basin. Construction of Keystone Dam began in January 1957 and the project was placed in operation in September 1964.

• The project is located on the Arkansas River approximately 15 miles west of Tulsa, OK

PROJECT LOCATION AND BACKGROUND

PROJECT FEATURES

Right Embankment Left Embankment

Gated (18) Spillway

Right Non-Overflow

Section

Left Non-Overflow

Section

Two Unit Power Plant

Switch Yard Project Office

Stilling Basin

Protection Stone:

60ft x 5.5 ft thickness 400 – 3000 lbs 60% between 800-1500 lbs

Endsill:

6 ft wide x 6 ft tall

Baffle Blocks:

12 ft tall ~30 CY per block

PROJECT FEATURES

SITE OVERVIEW

Brush Creek Park

Project Office

Hydropower Switchyard

Project Office Equipment Storge

Keystone State Park

~8.5 Miles

Sand Springs

Mannford HWY 97 Bridge

HWY48

White Water Recreation Area and ORV Park

HWY412

HWY51

PROPOSED MODIFICATIONS

Significant life safety risk exists at Keystone Dam (Risks that are not tolerable) Primary Focus Embankment overtopping associated with increased PMF above original Spillway Design Flood Potential for failure of the stilling basin during extreme flood events

Secondary Focus Right abutment seepage

DAM SAFETY RISK

Overtopping of the embankment by ~8 ft

Failure of the stilling basin (uplift or headcutting) leads to sliding of the overflow monoliths

Overtopping of Tainter Gates

Scour of embankment through upper limestone/sandstone in right abutment

Mech/Elec Gate Fail

A. Modify existing service spillway

• Raise existing spillway bridge

• Construct hydraulic deflector to protect existing spillway gates

• Raise concrete dam

B. Construct embankment raise

• Earthen/parapet wall combination

• Dam will be raised a total of ~11 feet

C. Construct temporary cofferdam

• Stilling basin divider walls and cofferdam will be used to create a dry working area below the dam

• Dam will be operated using 12 of 18 gates during construction

• Cofferdams are designed to wash out in the event the use of all 18 gates is necessary

D. Modify existing spillway stilling basin

• Anchor the right stilling basin training wall

• Install stilling basin slab overlay and anchor slabs to the underlying rock

• Replace existing baffle blocks and strengthen end sill

Components of Tentatively Selected Plan

Temporary Bridge and Cofferdam Locations

SELECTED PLAN TO ADDRESS RISK

INFRASTRUCTURE IMPACTS

Utilities

• No impacts to the switchyard, overhead powerlines, or telecommunications lines

• The telecommunications and power lines that cross the dam may be adjusted with the dam raise

Land Use

• White Water Recreation and ORV Park and Brush Creek Park would be closed for duration of construction

• Parking and access to the trailhead of the Two Rivers Trail may also be impacted

• Keystone Lake State Park would have altered access routes during construction

Hydropower

• No adverse impacts to hydropower are anticipated; operated in accordance with the water control manual

Water Management

• No change to the existing water level management for routine or flood operation of the dam

• No change to conservation or flood pool elevations

~11 FT Increase in effective height of dam

Rockfill

DAM RAISE OVERVIEW

Keystone Dam is in the design phase for Dam Safety Modifications. While not a focus of this industry, proposed modifications to the dam include:

• Raise effective height of embankment ~11 FT

• Earthfill/parapet wall combination

• Extension of dam into either abutment

• Spillway bridge raise and hydraulic deflector

• Demo existing top of piers

• Raise pier heights

• Construct new spillway bridge

• Hydraulic deflector supports

• Hydraulic deflector to span width of gate bays

• Non-overflow monoliths

• Raise non-overflow monoliths to match driving surface

New Impervious Fill

2.5

1.5

All Information is considered conceptual and is subject to change.

Demo top of existing piers and raise

~13 FT

~21 FT

New bridge at elevation of driving surface

Support for hydraulic deflector

Deflector Panels will span across gate bays

Remove/Replace Baffle Bocks Modify Endsill

Vertical Slab Anchors

STILLING BASIN MODIFICATION OVERVIEW

Keystone Dam is in the design phase for Dam Safety Modifications. The proposed stilling basin modification includes:

• Stilling basin slab concrete

• ~1 FT depth of slab demo with up to 3 FT of overlay

• Extension of existing slab drains

• Incorporation of new foundation drain conduits

• Stilling basin baffle block removal and replacement

• ~94 Baffle Blocks @ 30CY each

• Stilling basin endsill modification

• Stilling basin slab vertical post-tensioned anchors

• Anchors may include 2 – 3” DIA bars (~530 anchors)

• Anchors may include 30 – 40 strand anchors (~240 anchors)

• Anchor depths may range from 90 – 180 feet

All Information is considered conceptual and is subject to change.

Stilling Basin modifications will be optimized during design

SLAB AND POST-TENSIONED ANCHOR LAYOUT

All Information is considered conceptual and is subject to change.

Maintain Ability to Use All Gates If Needed Will Require Repairing Work/Cofferdam

1 2 3 4 5 6 13 14 15 16 17 18

STILLING BASIN ACCESS OVERVIEW

Two new splitter walls to perform work in the stilling basin while maintaining operation of the project

Potential Intermediate Pier

~285 FT

~285 FT

~285 FT

In-the-wet concrete wall (founded on drilled shafts)

~35 ft height ~6 ft top width

~10 ft base

Divider wall doweled into existing weir

(constructed in-the-dry using a dewatering structure) ~ 8 ft thick

~10 ft height (normal to weir)

Cofffercells:

~32.5 ft DIA 29 ft height

The piling will sit flush with the riverbed and will be backfilled with

5ft concrete, sand/gravel fill, concrete cap

STILLING BASIN ACCESS OVERVIEW

Existing Protection StoneDrilled Shafts:

~30 - 60” DIA

~22.5 ft depth below stilling basin floor

Baffle Blocks to be removed

Drilled Shafts:

~4 - 54” DIA

~22.5 ft depth below stilling basin floor

Blocks lowered to accommodate barge draft (2FT depth above blocks at low tailwater)

Baffle Blocks:

7.5 ft wide 18 ft O.C.

164 FT

60 FT

221 FT

STILLING BASIN ACCESS OVERVIEW

9.5 ft

5 ft 3 ft

2 ft

35 ft

22.5 ft

7.5 ft

Varies 8 - 10 ft

Splitter Wall Joint Layout:

Vertical joints every 30 feet and a horizontal lift joint at mid-height PVC waterstops at all joints

STILLING BASIN ACCESS OVERVIEW

• The earthen cofferdam will be constructed in-the-wet to ~EL 643 – 645 (1 or 2-unit hydropower discharge)

• The area between the phase 1 cofferdam and the spillway will be de-watered to construct phase 2

• De-watering wells will be constructed along the downstream side of the stilling basin

• The cofferdam will be sacrificial if spillway releases requiring all 18 gates are necessary

CONSTRUCTION / LAYDOWN AREAS

Approximate Construction Limits (lake, dam, channel, access) FEMA Floodplain mapping

Lake Office Storage Yard Use and Staging Area (Wekiwa Rd) Staging Area near SWPA (no impact to SWPA infrastructure)

All Information is considered conceptual and is subject to change.

South (Right Abutment) Staging Area Below Dam

Access Route – North Side of Channel

• Use Wekiwa Road from S 209th West Avenue to Staging

• Use Wekiwa Road from SH-151 to Lake Road to

Staging

Access Route – South Side of Channel

• Use SH-151 to Old State Hwy 51 Road to Inspection

Road

POTENTIAL WORK SEQUENCING

Baffle blocks removed in preparation for splitter wall construction.

Removed Half Height

POTENTIAL SEQUENCE OF WORK

Construct Right Splitter Wall From Barge

Construct Coffercells from Rockfill Causeway

Erodible Coffer Dam

Remove Causeway and Install Cofferdam

Coffer Dam

Begin Construction of Left Splitter Wall Complete Right Bay

Erodible Coffer Dam

Dewater Complete Anchors Complete Overlay

Replace Baffle Blocks

Move Cofferdam, Install Temporary Bridge and Remove Causeway

Coffer Dam

Complete Center Bay

Erodible Coffer Dam

Dewater Complete Anchors Complete Overlay

Replace Baffle Blocks

Coffer Dam

Dewater Complete Anchors Complete Overlay

Replace Baffle Blocks

Alternate access to the left bay

Dewater Complete Anchors Complete Overlay

Replace Baffle Blocks

CONSTRUCTION CONSIDERATIONS

CONSTRUCTION IMPLEMENTATION RISKS

• No viable operational changes to the project to facilitate construction

• Little benefit associated with a lowered conservation pool and increased social/environmental concerns

• Existing level of flood risk management must be maintained

• Construction of splitter/divider wall

• Limited to AUG – FEB to minimize spillway release probability

• Hydropower will be generated as needed to meet demand

• Spillway operation during this phase is expected to require demobilization from the stilling basin

• 2 Permanent splitter walls required to minimize loss of work due to moderate releases

• Allows for work in 1/3 of the basin while releasing from the other available spillway bays

• Allows for releases near channel capacity without significant damage to work in open bay

• Release approaching 100 kcfs (1/10 AEP) or near the top of flood pool (1/5 AEP) is expected to require evacuation of the work area

• All 18 Tainter gates must be available for spillway releases

• Change in materials cost during construction, especially considering a multiple year project (fly ash, cement, steel, etc.)

• Unknowns with the condition of stilling basin concrete (only Dive/ROV inspections available)

• Slope stabilization behind spillway walls

• Work restrictions to reduce risk (paving lanes, limit number of baffle blocks that can be removed, etc.)

USACE PDT will be the designer of record but will solicit contractor input in PED through the acquisition process

USACE will develop contractor limitations for stilling basin work to reduce risk during construction

Contractor limitations are intended to limit open work areas so the spillway can be made operational within USACE defined warning times. Expected to apply to:

Drilled shafts

Baffle block removal (for both the splitter wall and modifications following de-watering)

Maintaining a robust de-watering system

Concrete overlay and anchor sequencing

Endsill replacement

Spillway gates out of service during construction

USACE to use information obtained during Industry Days to inform 35% documents

IDaC contract (if pursued) is expected to target 65% design to help inform constructability and cost related design decisions. PED support will include development of a detailed construction schedule with a focus on project sequencing.