Draft Statement of Findings for Floodplains Management - Mint Springs Bayou Stabilization

The National Park Service (NPS) announces the availability of the Draft Floodplain Statement of Findings for Mint Spring Bayou Slope Stabilization. The NPS at Vicksburg National Military Park proposes to stabilize an eroding bluff adjacent to the Vicksburg National Cemetery in the Vicksburg National Military Park (the park). A previous project completed in 2011 consisted of the installation of two soil nail walls with shotcrete facing. At the base of the existing lower nail wall, the soil has become unstable and is sliding to the south causing movement of the Mint Spring Bayou bank in response. To stabilize the eroding slope adjacent to the Mint Spring Bayou, the National Park Service proposes to install a Mechanically Stabilized Earth retaining wall and a stabilized earthen berm. The wall will stabilize the slopes with the use of precast blocks or panels for the wall face and reinforced with layers of geogrids placed within the material placed as backfill for the wall. The wall will be approximately 316 feet in length and approximately 20 feet high, though the specific height may vary along its length. Horizontal drains will be constructed along the base of the upper two slopes in order to reduce water infiltration into the slope soils and facilitate drainage of the slope soils.

The proposed slope stabilization activity is necessary to protect portions of the Vicksburg National Cemetery that are being lost through continued erosion. The base of the failing slope is located in the 100-, and 500-year floodplains; and therefore, part of the stabilization must be located in the Regulatory Floodplain. The project was reviewed and based on the location, type of project activities and Draft Statement of Findings for Floodplains the NPS has determined that the proposed action is categorically excluded from further documentation under the National Environmental Policy Act (NEPA) as there are no extraordinary circumstances that may significantly affect the environment.

The interested public and agencies were provided an opportunity to review and comment on the proposed project during a 30-day review period from May, 23, 2016, through June 23, 2016. The NPS notified individuals, businesses, organizations state, county and local governments, federal agencies and culturally affiliated American Indian tribes. A total of 28 correspondences were received during the public comment period. No comments expressed opposition to the project. Comments received during the notice period expressed interest in providing public access, walkways and trail connections from the National Cemetery Arch to the river batteries and the waterfall along Mint Springs Branch. Some commenters provided recommendations for design features and best management practices to protect Mint Springs Branch and Bayou; the NPS will take these into consideration during the final design stages and implementation of the selected alternative. To protect Mint Springs Branch and Waterfall, a protective vegetative buffer will be maintained; all work will be set-back from the protective vegetative buffer. Slope stabilization measures will divert water away from the slope through vertical drains; the erosion protection measures will be installed to prevent erosion along the bottom of the slope.

The NPS finds that the repair and stabilization of the slope at Mint Springs Bayou and management actions to maintain the floodplain functions and values within the bayou are essential for public use and safety, despite the fact that the actions will be located along the edge of flood-prone areas. There are no practicable alternatives to enhance resiliency outside of the floodplain since the project site and the Mint Springs Bayou is within the 100-year floodplain; however, it is necessary to protect portions of the Vicksburg National Cemetery that are being lost through continued erosion at Vicksburg National Military Park.

Document Content:

VICK 209252 SOF Draft_8.12.2016.pdf   (4.0 MB, PDF file) Disclaimer: Links within the above document(s) were valid as of the date published. Note: Some of the files may be in PDF format and can be viewed using the Adobe Acrobat Reader software. You may download a free copy of from Adobe Systems.