A draft revised environmental assessment for PL 84-99 levee rehabilitation activities at L-575 along the Missouri River is currently available for public review.
Rehabilitation activities consisted of in-line repairs to bring the levee back to pre-flood conditions and construction of two large-scale levee setbacks. An EA was prepared for the known repairs prior to construction in December 2011, however as final design and construction activities proceeded, the need for more extensive repairs including large-scale setbacks was revealed. Based on need for timely completion of the emergency repairs, a revised environmental assessment was not fully completed until after construction had been mostly completed.
The draft revised EA primarily focuses on evaluation of the effects of the large-scale levee setbacks between river miles 566-556.
This draft revised EA is consistent with the National Environmental Policy Act of 1969 (NEPA), as amended, the Council on Environmental Quality’s (CEQ) regulations for implementing NEPA (40 CFR 1500-1508), the Corps’ regulations for implementing NEPA (33 CFR 325 and Engineering Regulation 200-2-2), PL 84-99, and other applicable environmental laws and regulations.
Rehabilitation of L-575 occurred under the PL 84-99 Flood Control and Coastal Emergency Act in response to levee sponsor requests to repair damage to the levee caused by the 2011 flood. Initially, all in-line repairs on L-575 were implemented at damage and breach locations, except those along the large-scale setback areas.
By February 2012, all the breaches had been closed and by October 2012, the other non-breach structural repairs had been completed. The Corps was still determining whether or not large-scale setbacks would occur at both sites. The two large-scale setbacks were determined to be the most cost-effective approach to permanently fixing the levee.
The first large-scale setback near Iowa Highway-2 began in March 2012, concurrently with development of this revised EA. In late October 2012, a large-scale setback across the river from the OPPD coal-fired power plant, south of Nebraska City in Otoe County was initiated. Both setbacks were substantially complete at the time this draft revised EA was finalized.
Combined, the setbacks will open up approximately 1,860 acres of floodplain, reduce stages of the 100-year flood event by up to 1.6 feet, and reduce velocities of the 100-year flood event by up to 2.6 feet/second. Although incidental environmental benefits result from large-scale levee setbacks, habitat creation was not a purpose of this project. All wetland impacts were mitigated for concurrently during construction.
Press Release, June 6, 2013