B.08.Amendment W912EE25BA009-0003_TSLSC Pre-Bid Meeting Revised Slides.pdf
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- Solicitation number
- W912EE25BA009
About this file
This document is a pre-bid meeting presentation for the Thatcher Stoplog Slots Construction project by the U.S. Army Corps of Engineers Vicksburg District. The project involves constructing new stoplog slots at the Thatcher Lock and Dam on the Ouachita River, which is the last of the river locks to receive these upgrades. The work will be completed in 3 locations (6 slots total), with the goal of enabling dewatering of the miter gates and lock chamber.
The project scope includes removing existing concrete and handrails, installing new concrete, rebar, and steel bulkhead recess inserts, fabricating and installing new sill beams and support struts, and placing government-furnished bulkheads into the newly constructed slots. The contract duration is 210 days, with a planned Notice to Proceed (NTP) date of December 2025, though this may be adjusted. The government will provide steel cable slings for stoplog handling and has specified three different stoplog sizes (Types A, B, and C). Contractors are subject to subcontracting limitations, requiring the apparent low bidder to submit a Small and Disadvantaged Business Subcontracting Plan within 7 days of bid opening.
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Text version
8/26/2025
VICKSBURG DISTRICT
THATCHER STOPLOG SLOTS CONSTRUCTION
PRE-BID MEETING
AUGUST 12, 2025
U.S. ARMY CORPS
OF ENGINEERS
GENERAL PROJECT INFORMATION AND PROJECT
HISTORY
• The existing dewatering system for Thatcher Lock (Poiree Dam) has been retired due to safety concerns.
Stackable stoplogs have become the standard equipment for lock dewaters nationwide.
• Thatcher Lock and Dam is the last of the Ouachita River locks to have stoplog slots installed (Jonesville, Columbia, Felsenthal previously installed).
• The work will be completed in 3 locations (6 slots total). Once completed, either of the miter gates or the entire lock chamber will be able to be dewatered.
SITE LAYOUT
• Removal of existing concrete and handrails in locations where new stoplog slots will be constructed.
• Installation of new concrete, rebar, and steel bulkhead recess inserts (6 locations total)
- Work includes the fabrication of bulkhead recess inserts as shown on the drawings.
• Fabrication/installation of the new sill beams and sill beam support struts.
• Placement of Government furnished bulkheads into newly constructed slots and valve culverts.
• Placement of concrete around new sill beams and sill beam support struts.
• Replacement of handrails around work areas.
For the purpose of acceptance, the Stoplog Slots must be in place as shown in the drawings and must allow for dewatering of the miter gates and lock chamber.
SCOPE OF WORK
Work is anticipated to start at the upstream slots and work downstream. Once the upstream slots are constructed, the sill beam can be lowered into place attached to the bottom stoplog. The lower pool will be drawn down to 59.0 EL and the water behind the miter gate sill will be pumped out creating a dry area to work. If the upper sill beam assembly is to be constructed in the dry, the lock chamber pool will need to be lowered to 59.0 EL. Sill beam struts and concrete will be placed as shown in the plans. The contractor can then move to the downstream slot locations and begin work.
The contractor may submit alternative construction methods and sequences for government approval.
SEQUENCE OF WORK
8/26/2025
Monolith 5 section view.
SILL BEAM
SUPPORT
STRUT
SILL BEAM
UPSTREAMDOWNSTREAM
b4ecdsck Polygon b4ecdsck Polygon b4ecdsck Text Box
GOVERNMENT FURNISHED STOPLOGS
8/26/2025
• Government furnished stoplogs stack to adjust height of dewatering.
• Three different sizes/types of stoplogs: Types A, B, and C (C’s are largest and go on bottom).
• Stacking orders will be provided prior to construction.
• Lifting devices for the stoplogs shown in the As- Built drawings (Pick-up truss) are no longer used.
• Steel cable slings (Government provided) are now used.
Stoplogs in newly constructed slots at Felsenthal Lock and Dam.
Placement of a bottom stoplog using steel cable slings.
COFFERDAMS
• Cofferdams previously used on the Ouachita River locks for stoplog construction have been cell type cofferdams.
• The use of cofferdams that dewater an entire monolith of the lock are not prohibited but are not recommended due to strict water elevation requirements.
• .Cell type cofferdams can be built to the top of the lock wall.
UPPER POOL HYDROGRAPH (LAST 10 YEARS)
LOWER POOL HYDROGRAPH (LAST 10 YEARS)
10CONTRACT ADMINISTRATION – DURATION AND
TIME EXTENSIONS
Duration is 210 Days (see Amendment 1).
Amendment 1 revised the NTP to be issued on or about 1 December 2025 to allow for unwatering and maintenance at Jonesville Lock and Dam. However, Jonesville Lock unwatering has been rescheduled. The NTP date will be amended to immediately after verification of bonds.
– Jonesville Lock unwatering is anticipated for the summer of 2026. The Government will coordinate with the Contractor to minimize any impacts to the Thatcher stop log slot construction due to this closure including allowing passage of vessels through Jonesville Lock.
A noncompensible excusable delay will be granted for high water events preventing work including unwatering at the structure.
11CONTRACT ADMINISTRATION –
SUBCONTRACTING LIMITATIONS
Per FAR 52.219-14 Limitations on Subcontracting , subcontractors may not perform more than 85% of the amount paid by the Government for contract performance excluding the cost of materials.
Within 7 days of bid opening, the apparent low bidder shall submit a Small and Disadvantaged Business Subcontracting Plan. This does not apply to small business concerns.
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