July 22, 2024
FOR IMMEDIATE RELEASE
For more information contact:
Mattheuw Prenger, P.E.
County Engineer
Cole County Public Works
573.636.3614
mprenger@colecounty.org
Notice & Public Explanation
Final Notice and Public Explanation of a Proposed
Activity in a Floodplain and Wetland
To: All interested Agencies including the Missouri Department of Economic Development, the Missouri Department of Natural Resources, Federal and State Emergency Management Agencies, the Missouri Department of Conservation, Missouri Department of Fish & Wildlife, the U.S. Army Corp of Engineers, and the Environmental Protection Agency, etc., Groups and Individuals.
This is to give notice that the Cole County Commission as the Responsible Entity under Part 58 has conducted an evaluation as required by Executive Order 11988 and 11990, in accordance with HUD regulations at 24 CFR 55.20 Subpart C Procedures for Making Determinations on Floodplain Management and Wetlands Protection. The activity is funded under Title I of the Housing and Community Development Act of 1974 (PL 93-383) Community Development Block Grant project number 2021-WS-02.
The purpose of this project is to control stormwater flooding in a residential neighborhood. The project is located in Section 13, Township 44 North, Range 13 West, Cole County, Missouri (Latitude: 38.5607, Longitude: -92.2996). The project area is in a residential neighborhood in Jefferson City, Cole County, Missouri, bounded by Amanda Drive, on the west, Jasper Lane on the east, South Brooks Drive to the south except for two drainage areas running under South Brooks to the south, and Bagnell Drive to the north that is prone to flooding during storm events. The County proposes to build a 2.4-acre detention basin located north of Bagnell Drive, near the end of Jasper Lane, behind the houses on the north side of Bagnell Drive, north of Jasper Lane and Bradley Drive intersections with Bagnell Drive. This basin will be able to manage an additional 28.5 acre-feet of detention volume, which will help reduce the impact of a moderate to heavy rain event. The existing drainage areas between Bradley and Jasper, Bradley and South Brooks Drive and Bradley and Amanda Drive will have low-flow enclosed storm sewers installed and the ditches re-graded and recontoured. The two areas along South Brooks will have new inlets and enclosed pipes installed to facilitate water flow through the secondary channels into the larger channels south of South Brooks. Approximately 1,750 feet of ditch will be reconstructed, 2721 linear feet of enclosed storm sewer added, and 29 inlets and drop boxes will be installed to accommodate flow into the new systems. The total project area is approximately 46 acres. These improvements will increase stormwater capacity thereby reducing the likelihood that rain events will create flash flooding downstream, and the redesigning of drainage ditches will eliminate areas of pooling and ponding thereby reducing mosquito infestation.
The National Wetlands Inventory lists a pond which historically existed north of South Brooks Drive between Truman Drive and Amanda Drive. This is classified as a nontidal wetland, code PUBK (Palustrine, Unconsolidated Bottom, Artificially Flooded) dominated by trees, shrubs, and persistent emergences, where flooding is controlled by dikes, berms and or dams, however the area has been developed into a residential subdivision and homes now occupy this land. The National Wetlands Inventory also lists a riverine wetland which is part of the existing drainage area between Bradley Drive and Jasper Lane. This is a nontidal wetland, classification code R4SBC (Riverine Intermittent Streambed, Seasonally Flooded). There is another riverine wetland listed which is part of the existing drainage area running south of South Brooks Drive. This is a nontidal wetland, classification code R4SBCx (Riverine Intermittent Streambed, Seasonally Flooded, Excavated). R4SBC features only carry surface water in their channels at certain times of the year or after precipitation or melting events. These riverine wetlands are dry unless there is a major rain event and are no longer true wetlands due to construction alterations that have occurred in the area beginning in 1980. According to FEMA, the lower section of the project area near the wetland south of South Brooks Drive is flood zone A, also referred to as 100-year floodplain. The natural and beneficial functions of the floodplain and wetland include floodwater storage and conveyance, groundwater discharge or recharge, erosion control, water quality maintenance, and habitat for flora and fauna. This project area’s wetlands and floodplain are not known to have any significant recreational, educational, historic, scientific, or cultural values. Approximately 5 acres of existing and/or historical wetland and 3 acres of floodplain are within the project area and may be affected by the proposed activities.
Cole County Commission has considered the following alternatives and mitigation measures to be taken to maximize adverse impacts and to restore and preserve natural and beneficial values. The project must take place in a floodplain and wetland because stormwater improvements are necessary to reduce flooding in this residential neighborhood where floodplains and wetlands exist. Alternatives considered include: 1) Do Nothing: The drainage ditches have deteriorated to a state where they are not able to adequately manage the storms which frequent the system. It is vital that action be taken to remedy the current condition of these drainageways, therefore this alternative was not selected; 2) Ditch Lining and Culvert Reconstruction: The second alternative would consist of reconstructing the ditch to alleviate the areas of siltation, erosion, or vegetative growth. This will require relocating all existing private improvements near the ditch. If the existing drainage easement is utilized, the channel will need to be re-routed as it has meandered from the easement in multiple locations. For long-term maintenance, the system would be concrete-lined for its entire length to increase capacity and reduce the likelihood that similar issues which restrict capacity would happen in the future. Side street enclosed storm sewer systems would be outlet with end sections into the concrete-lined channel. This alternative was not selected because of higher project costs, the need for concrete lining which would increase impermeable surfaces, and the need to regrade and expand the drainage ditches; 3) Detention and Ditch Improvements: The third alternative consists of regrading the ditch to alleviate current constructions. The use of an upstream detention basin will be required to reduce flows, allowing for the new ditch to be a smaller overall size – this will allow for gentle side slopes which will be easier for the county and private individuals to maintain in the future. To further ease future maintenance, a system of enclosed pipes and inlets will be placed along the length of the drainage channels to accept low flow water and prevent future ponding along the drainageway. The detention basin will serve to alleviate flooding in this immediate area and further downstream as well. This is the selected alternative because it addresses the flooding issues in the neighborhood at a lower cost and minimizes modifications to the wetland; 4) Alternative Located Outside the Wetland and Floodplain: Under this alternative, a larger, regional detention basin would need to be constructed to reduce water flow in the drainage ditches. Drainage ditches would not be regraded and improvements such as enclosed pipes, culverts, and inlets would not be installed. Private infrastructure which impedes water flow would be left in place. This alternative was not selected due to the cost and additional land required to expand the detention basin to serve the region without conducting any work in the wetland or floodplain. The Commission has determined that detention and ditch improvements will provide the most beneficial, long-term, safest, and most cost-effective results for the residents living in the project area. Mitigation measures to be taken to minimize adverse impacts and preserve natural and beneficial functions of the floodplain and wetland include relocation and/or reconstruction of private infrastructure which impede effective flow and minimizing excavation and additional impermeable surfaces in the wetland.
This project complies with Cole County’s Floodplain Protection Management plans. It will minimize the need for relief efforts at the expense of the general public and protect human life and health. The project will comply with the Cole County Floodplain Management Ordinance and any required floodplain development permits.
Environmental files that document compliance with steps three through six of Executive Order 11988 and 11990, are available for public inspection, review and copying upon request at the times and location delineated in the last paragraph of this notice for receipt of comments.
There are three primary purposes for this notice. First, people who may be affected by activities in floodplains and wetlands and those who have an interest in the protection of the natural environment should be given an opportunity to express their concerns and provide information about these areas. Second, an adequate public notice program can be an important public educational tool. The dissemination of information about floodplains and wetlands can facilitate and enhance Federal efforts to reduce the risks associated with the occupancy and modification of these specific areas. Third, as a matter of fairness, when the Federal government determines it will participate in actions taking place in floodplains and wetlands, it must inform those who may be put in greater or continued risk.
Written comments must be received by the Cole County Commission at the following address on or before July 29, 2024: Cole County Commission, Cole County Courthouse, 311 East High Street, Jefferson City, MO 65101, or at (573) 634-8031, between the hours of 8:00 a.m. and 5:00 p.m. Attention: Sam Bushman, Cole County Commissioner. A full description of the project may also be reviewed from 8:00 a.m. to 5:00 p.m. at the above address. Comments may also be submitted via email at sbushman@colecounty.org.
Date: July 29