The Metropolitan Sewerage District’s (MSD) Sanitary Sewer Improvements at Carrier Bridge are being completed to accommodate growth in the western and southern areas of Buncombe County, and northern parts of Henderson County. The improvements will be centered around MSD’s Carrier Bridge Pump Station, located near the confluence of the French Broad and Swannanoa rivers.
The project includes replacement of Carrier Bridge Pump Station and rehabilitation of the French Broad Interceptor, a large gravity sewer paralleling Lyman Street and the Wilma Dykeman Greenway. The project is anticipated to be complete by 2029.
These improvements are essential for accommodating future wastewater flows (including wet weather events) and protecting the quality of the French Broad River. Further details and a breakdown of the project areas are provided below.
This project is located north of the existing Carrier Bridge Pump Station (CBPS) off Riverview Drive, adjacent to the City of Asheville’s French Broad River Park. The project will replace the existing CBPS, MSD’s largest pump station, originally constructed in 1966. Wastewater from the southern and western portions of MSD’s service area is conveyed into the station and is pumped across the French Broad River to the French Broad Interceptor, a 54-inch gravity sewer.
Multiple upgrades have been made throughout the years to maximize the pump station’s capacity which is currently 23 million gallons per day (MGD). The new pump station will be designed with sufficient capacity to meet projected growth for the next 50 years and beyond. The replacement station will have an initial capacity of 40 MGD with the capability of future expansion to 50 MGD with minor upgrades.
This project will include the construction of the new pump station and odor control system, abandonment of the existing station, installation of approximately 800 feet of new 60-inch influent gravity sewer, and installation of approximately 1,500 feet of parallel 36-inch discharge force mains connecting the pump station to the French Broad Interceptor on the east side of the river. The parallel force mains will be installed across the river using rock coffer dams to temporarily divert river flow to one-half of the river channel. These dams allow MSD’s contractor to isolate and dewater the work area prior to pipe installation.
River crossings are complex and require a specialized contractor. With the contractor already “mobilized” in the area for the CBPS project, a second river crossing will be constructed further upstream at Carrier Park for a future sewer project. Utilizing the contractor for this second crossing will result in cost savings to MSD.
This portion of the project is located along Lyman Street next to the Wilma Dykeman Greenway. Approximately 2,000 feet of existing 48-inch and 54-inch reinforced concrete gravity sewer pipe will be rehabilitated using a trenchless technology called Cured-In-Place-Pipe (CIPP) Lining. The technology uses a resin-impregnated liner pipe that is inserted into the existing sewer pipe, inflated, and cured via steam, hot water, or UV light. The final product is a new pipe inside the old pipe, and the process is completed with minimal disruptions and surface disturbances.
The existing concrete pipe, installed in 1966, is in poor condition and has deteriorated due to the release of hydrogen sulfide, a gas present in all domestic sewer systems. The new CIPP liner will restore deteriorated sections of the French Broad Interceptor while also providing corrosion-resistance.
At the northern terminus of the interceptor rehabilitation project, a new junction box will be constructed to connect the parallel 36-inch force mains (mentioned above) from CBPS to the French Broad Interceptor. Installation of the junction box and CIPP liner will require the use of bypass pumps and piping to temporarily divert wastewater around the project site while work is being completed.
Sanitary Sewer Improvements at Carrier Bridge. (Click the picture for larger image).
In January 2024, the US Army Corps of Engineers and NC Department of Environmental Quality issued approval for the two (open-cut) sanitary sewer crossings of the French Broad River.
Final design of CBPS and associated projects (described above) is in progress with 90% design submittal anticipated in Fall 2024. Additional permitting and easement acquisition will follow, and bidding & award in Fall 2025.
Construction is expected to begin late 2025/early 2026 and is anticipated to last approximately 3 years.
The French Broad River Park is expected to remain open; however, construction activities will interfere with use. The portion of the project along Lyman Street and RADTIP Greenway will involve a large, temporary sewer bypass pumping and piping system that will require the greenway to be closed in the area of construction. Occasionally the southbound lane of Lyman Street will be closed for certain construction activities. Closures are also anticipated at the City of Asheville baseball/softball field west of Carrier Park.