By Leslie Jacques, AGSC/ADB Marketing Manager and Tim Martin, ADB Quality Control Manager
In a video released by the U.S. Army Corps of Engineers (USACE) in early February, Todd Tobias, Construction Representative of USACE Omaha District, expressed that the L594 Levee is now flood fight ready. He also expressed that in the construction world, this project is on time and under budget.
Ahtna Design-Build, Inc. (ADB), in its 3rd joint venture with CDM Smith known as Klutina River Contractors (KRC), has been highly praised and recognized for its successful execution of this project. As work along the Missouri River continues, a total of 22 Design Modifications (DM) have been issued on the project. Currently the contract value has reached $57.2 million as of February 19, 2021, with an expectation of additional DMs potentially reaching $61 million. To date KRC has moved approximately 2.8 million cubic yards of material on this project.
The original scope of the L-594 task order contract was for the closure of three outlet breaches (C, D, and E) which occurred along a 14-mile levee system. This work is part of the USACE’s ongoing efforts to repair more than 500 miles of levees damaged by floods along the Missouri River in Nebraska and Iowa in 2019. These repairs are directed at stopping the flow from the Missouri River into the area behind the levee system and providing an incremental level of flood risk protection to help ensure the safety of surrounding residents. All field operations were to be completed by the end of March 2020; however, based on the project success and the USACE Omaha District’s satisfaction with the collaboration efforts and production rate of the KRC team, the project contract was modified several times to address several other levee issues and elements.
As the prime contractor, KRC has to date completed the construction of the original contract ring levee breach closures, temporary closure completion at Breach A, geotechnical investigation, and construction of an 8,576-foot setback levee and trailing dike, including both land and riverside ballast berms. KRC was also responsible for the testing and abandonment of 39 existing relief wells and 45 toe drains, video, and engineering inspection of seven drainage structures.
KRC has a field management staff of 6 personnel which manages a crew of approximately 45 onsite equipment operators. The KRC field management staff oversees and reports on the civil construction. These repairs include fixing erosion within the levee system’s critical sections, reconstruction of the levee crest, regrading, and riprap placement. Once the earthwork was completed, the levee system repairs were blanketed and seeded for the final work activity.
KRC was able to contract with two local grading subcontractors with extensive levee construction experience. These subcontractors came together to facilitate the construction means and methods and to ensure compliance to the contract. With this team, KRC had approximately 45-plus pieces of earth moving equipment working on the project and the required levee improvements. The KRC field management staff and crews worked 8 to12-hour days, 6 days a week to meet the time critical setback levee closure mandate of March 1, 2021. KRC had to construct haul roads to each levee breach and identify, test, manage and rehabilitate/restore 15+ random fill and cohesive borrow sources, some as far as 10 miles away, for the existing levee repairs as well as the new setback levee.
Remaining items to be completed are trailing dike construction, access gates for the levee, 5,000’ of new toe drain, pile supports for two drainage structures, seepage berm extension drainage, levee surfacing, haul road repair and resurfacing, completion of the removal of 8,000’ of existing levee, rehabilitation of land and riverside affected areas at the new setback levee, and seeding and Erosion Control Blanket (ECB) installation. The target date for existing contracted work and future anticipated modifications is June 1, 2021.