A rendering of the plans to replace and expand the Southside Wastewater Treatment Plant, with the old plant shown at left. Courtesy CFPUA.

A year and half ago, I shared early plans for the largest infrastructure investment in CFPUA’s history: replacing the Southside Wastewater Treatment Plant. Customers will soon see work begin at the River Road facility as this critical community asset takes shape. 

CFPUA’s Board kicked off 2025 with a workshop to finalize plans for the Southside Expansion and Replacement Project. 
The plant, constructed in 1972, is one of two wastewater treatment plants owned and operated by CFPUA. It receives about half of the 6.4 billion gallons of wastewater CFPUA treats each year, mainly from the southern parts of CFPUA’s service area.

At 52 years old, the plant has earned its upcoming retirement. As we get ready to kick off work at the site this year, here’s what customers can expect:

Where will the new plant be built? 

The new plant will sit just south of the existing Southside Plant on River Road, between the Port of Wilmington and Independence Boulevard.

Over the past several years, CFPUA acquired acreage around the existing Southside Plant campus, allowing us to build right next door while still operating the current plant during construction. While a handful of recently renovated buildings at the existing plant will remain, including our Centralized Maintenance office and the biosolids handling facility, almost all the new plant’s infrastructure will be entirely new construction.

We look forward to kicking off site work, including clearing and leveling land, in late 2025 and early 2026. 
 
What features will the plant have? 

The rebuilt Southside will boast new treatment technologies as well as infrastructure to handle larger amounts of wastewater. 

The current plant is permitted to handle up to 12 million gallons per day (MGD) of wastewater. The replacement will be built to treat up to 16 MGD, on par with CFPUA’s Northside Wastewater Treatment Plant, which was upgraded in 2009. 
Expanding Southside’s capacity will allow the plant to stay ahead of high-density growth in parts of CFPUA’s service area such as Carolina Beach Road, River Lights, and Independence Boulevard.

How will the new plant protect the environment? 

Even at age 52, Southside continues to meet – and out-perform – federal and State standards for wastewater. However, while spills and overflows at the existing Southside Plant are rare, we know the older the infrastructure gets, the higher the likelihood becomes for problems. 

In addition to fully replacing aging infrastructure across the plant, the project will add an aeration treatment facility at Southside.

Aeration, already in use at CFPUA’s Northside Plant, is a wastewater treatment method that harnesses the power of microbes, often called “bugs,” to break down waste and remove carbon, nitrogen, and phosphorus. This will allow the new plant to remove even more nutrients and contaminants from wastewater. 

Unlike some portions of the existing plant, the new Southside will also be built entirely above the 500-year floodplain, decreasing the potential for inundation during major storms. 

What happens to the old plant?

For now, the old plant isn’t going anywhere – though it will no longer be operating after the new plant is built. 
The CFPUA Board opted to forgo demolition of the existing plant infrastructure as part of this project. While final project costs are still being determined by our engineers, not demolishing the current plant will trim an estimated $8.8 million from the project total. 

Should the new Southside Plant need to expand decades from now, those old pieces of infrastructure can be demolished and replaced as needed. 

Follow our progress over the coming years at www.CFPUA.org/Southside.