Ahtna Team Delivers Critical Flood Risk Reduction

Published April 2020

By Leslie Jacques, AGSC/ADB Marketing Manager and Brian Gough, ADB Director of Construction

Klutina River Contractors (KRC), the third joint venture entity formed between Ahtna Design-Build, Inc. and CDM Smith, was awarded a $22 million task order contract by the United States Army Corps of Engineers (USACE) Omaha District for the L-594 levee system repairs along the Missouri River in Fremont County, Iowa. This task order was awarded under the USACE’s $95M Rapid Disaster Infrastructure (RDI) 8(a) Set-Aside Multiple Award Task Order Contract (MATOC), which KRC was awarded in 2019.

The scope of the L-594 task order contract is for the closure of three outlet breaches (C, D, and E) which occurred along an 18-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.

As the prime contractor, KRC has a field management staff of 12 personnel which manages a crew of approximately 60 onsite equipment operators. Our field management staff oversees and reports on the civil construction to repair crest and land side slope damage areas of the breaches. These repairs include constructing ring levees within the breaches and repairing erosion within the levee systems’ critical section; reconstruction of the levee crest, regrading, and riprap placement; and sediment and debris removal on the levee slopes, crest and berms. Once the earthwork was completed, the levee system repairs were blanketed and seeded for the final work activity.

KRC held their pre-construction meeting on December 17, 2019 and began the interim levee repair work on January 6, 2020. The team temporarily closed the three outlet breaches along the L-594 levee with random fill sand by February 10, and then commenced the placement of the cohesive material along the faces of the breach repairs. The period of performance for these repairs was approximately 120 days, with the breach repairs being entirely completed by March 1.

Ahtna Design-Build’s Director of Construction serving as Area Manager for this contract, Brian Gough, described the inclement weather conditions during these activities as typical midwest weather at this time of the year, with temperatures at below freezing most every day and frozen ground conditions. The freezing conditions sometimes made it difficult to direct place the random fill as the material was frozen to the side walls of the dump truck, but the crew was able to adapt by having a piece of equipment assist in the dump and make sure all material was placed. The field staff and subcontractors were able to implement winter weather construction techniques to continue with all associated earthwork activities and maintain the compressed schedule.

KRC was able to contract with three local subcontractors, which all had extensive levee construction experience especially in breach closures. These subcontractors came together to facilitate the construction means and methods and to ensure compliance with the contract. With this team, KRC had approximately 60 plus pieces of earthmoving equipment working on the project and the required levee improvements. The field management staff and crews worked 12-hour days, 7 days a week to meet the time critical closure mandate of March 1. Upon mobilization, KRC had to construct haul roads to each levee breach and identify the random fill source for each breach. The daily production in cubic yards for the random sand fill placement operation was typically between 16,000 C.Y. and 18,000 C.Y. and occasionally over 20,000 C.Y. per day requiring over 800 truck trips. The total amount of material placed to temporarily close all three breaches was an impressive 336,000 C.Y. The team then focused on placing upwards of 165,000 C.Y. of cohesive fill material to cap the random fill placed and to protect the river and land side of the levee. The same type of daily production on the cohesive material was achieved to meet the strict schedule mandate. While the cohesive material was placed at each breach, KRC had a crew working on the other levee system crest repairs and all levee surfacing. After the March 1 critical repairs were completed, KRC and the team started the placement of topsoil over all affected areas, placement of erosion control blanketing, and final seeding.

All field operations were to be completed by the end of March weather permitting; however, the USACE Omaha District program personnel are extremely impressed by the collaboration, efforts and production rate of the KRC team. They are discussing potential modifications of the contract to address additional areas of the levee system requiring repairs, including additional scour holes that were only identified after the water receded, and a possible new levee alignment.

“Even with the recent winter weather, the team has remained steadfast in their commitment to restoring the L-594 levee system. This team is comprised of companies that are oftentimes direct competitors but have come together under the common goal of repairing the damaged levee system that is vitally important to the communities and landowners behind it. Closing these two breaches is a direct reflection of the field team’s leadership and problem-solving mentality,” said Corina Zhang, USACE Resident Engineer for L-594 Project.

“This breach closure is a milestone for the flood recovery effort, as this marks the first of the left bank Missouri River Levee Systems that were severely damaged by the March flood event to be fully closed. However, the team knows that we still have a lot of work ahead of us and will continue to try and repair the damaged levees as quickly and efficiently as possible,” said Mary Darling, Project Manager for the Omaha District Systems Restoration Team.