W912EE - The USACE Vicksburg District is seeking qualified and capable contractors with the capability and capacity to perform the scope-of-work indicated, capable of mobilizing immediately after the receipt of Notice-to-Proceed.

In accordance with Federal Acquisition Regulation (FAR) 36.204(f), the estimated magnitude of construction is between $1,000,000 and $5,000,000. This project has an estimated completion time of 90 Calendar Days after the receipt of Notice to Proceed, including the time for prework submittals and material procurement.

NAICS – 237990 – Other Heavy and Civil Engineering Construction, with a small business size standard of $45M. 

PROJECT SPECIFIC DETAILS:The U.S. Army Corps of Engineers, Vicksburg District requests letters of interest from qualified construction contractors capable of performing construction services for the following project:

Desoto County, Mississippi, Arkabutla Lake Dam, Outlet Works Foundation Grouting, Coldwater River, Arkabutla Lake.

Foundation Grouting

The Arkabutla Dam outlet works’ foundation is planned to be grouted due to ongoing settlement and instability regarding internal erosion. Approximately, 630 grout holes using solution grouts only (combination of resin and polyurethane grouts) will be utilized within the entire area along the transition, conduit, and select areas of the stilling basin under this plan. The goal of the project is to fill voids beneath the conduit and stilling basin at safe injecting pressures meeting the requirements of USACE regulation ER 1110-2-1807.

The intake structure is approximately 123 feet long (including the transition) and 59 feet wide at the base. The reinforced concrete conduit is 325 feet length with an (inverted egg) shaped section that is 16 feet by 18.25 feet dimension and composed of thirteen monoliths. Each monolith is 25 feet in length. Steel reinforcement include 1 1/8-inch bars on 6-inch c.c. within the transition while the conduit has 1 1/8-inch bars on 8-inch c.c. The reinforced stilling basin has a 72.5-foot-long chute which drops by steps and discharges into a 75 feet long stilling basin with two rows of baffle blocks.

Within the conduit, the solution grouting will be injected via a series radial grout lines spaced on
6-foot offsets. The primary holes will be advanced to a depth of 4 – 8 feet and grouted using polyurethane grout with the intent to fill voids near the conduit monolith joints.  The secondary holes will be advanced to a depth of 8 – 12 feet and grouted using resin grout with the intent to permeate loose sandy zones that exist below the conduit monoliths. Two sets of primary and secondary grout lines will be place per monolith. Tertiary grout holes will be drilled and grouted by split spacing between the primary and secondary grout lines as assigned by the government based on observed grout takes and pressures and advanced to a depth of 4 – 12 feet. The government assumes 156 tertiary holes will be advanced to a depth of 4 – 8 feet as assigned by the government.  Allowable drilling methods will only include rotary drilling or non-fluid (push) methods to be drilled through the 3.5 feet of concrete at the bottom section of the conduit.

A demonstration section will be completed in an area downstream of the main embankment and away from the conduit and selected by the government first to determine effectiveness of the grouting and to allow what few grout injections were made to be dug up and replaced with suitable material if required. This demonstration section will be required to be completed prior to starting work within the outlet works and will not count against the 45-day dewatering closure.

Once the conduit foundation grouting is completed, grouting in select areas of the stilling basin will also be completed from upstream to downstream. Coring of the 5-foot-thick concrete slab will be required to complete the grouting. There are also ten (10) 4-inch drains that exists across the lowest chute step leading from the conduit exit to the stilling basin. These drains discharge excess seepage flows from the outlet works foundation in order to relieve pressures. The system is currently compromised but closed off with a steel plate and gasket bolted to the exterior of the drains. The steel plates will need to be removed so that these drain holes can be grouted with a cementitious grout mixture for proper abandonment. The contractor will be required to replace the steel plate and gasket to the exterior of the drains.

The government will pump wells at the outlet works along the top of dam, downstream berm, and backfill locations to lower the phreatic surface during the grouting campaign except in the immediate area where grouting is occurring to prevent undesirable movement grout to the relief wells. The government will also be