OMAHA, NE – A draft environmental assessment for repairs to Missouri River levee unit L-550 near Langdon in Atchison County, Missouri is currently available for public review. The draft EA evaluates the environmental impacts of repairing damage within a drainage ditch located between L-550 and Rock Creek caused by high precipitation events in 2015 and 2016. Repairs are needed to prevent seepage of levee foundation material from L-550 into the drainage ditch.
The project proposes to reduce the threat of uncontrolled seepage by lowering outfalls from six existing relief wells and tying them in to a new 60-inch diameter reinforced concrete pipe that extends 300 feet within the drainage ditch. Repairs will be completed under the USACE PL 84-99 Emergency Levee Rehabilitation Program.
BACKGROUND: Following an unusually wet fall in 2015, soil moisture content was above average across most of the lower portion of the Missouri River basin. Between November 2015 and January 2016, events of greater than 200 percent of the normal precipitation fell across the area. Active rain storms from late April into mid-May 2016 added to the already saturated soil conditions. Atchison County Levee District #1 (the Project Sponsor) noted flood waters against the L-550 levee were causing active boils on the landside levee toe and within a drainage ditch that runs adjacent to both the levee and the toe of the L-550 seepage berm. In August 2016, USACE conducted a damage survey and noted boils occurring in the drainage ditch. Two of the boils identified were approximately six to eight inches in diameter and were likely moving a small amount of foundation material. Several other smaller boils that were flowing clear, were also identified. USACE also noted in the damage survey report that the L-550 levee was in an active status and eligible for PL 84-99 assistance.
The public is encouraged to provide comments on the draft environmental assessment, which is available for viewing at http://www.nwo.usace.army.mil/Missions/Civil-Works/Planning/Project-Reports/. Comments can be mailed to: U.S. Army Corps of Engineers, Omaha District; CENWO-PM-AC; ATTN: L-550 EA; 1616 Capitol Avenue; Omaha, NE 68102-4901. Comments can also be emailed to: cenwo-planning@usace.army.mil. Comments must be postmarked or received no later than October 27, 2016.
This draft EA is consistent with the National Environmental Policy Act of 1969, as amended, the Council on Environmental Quality’s regulations for implementing NEPA (40 CFR 1500-1508), the Corps’ regulations for implementing NEPA (33 CFR 325 and Engineering Regulation 200-2-2) and other applicable environmental laws and regulations.
Release no. 20160928-001