With $239 million in financing secured from the Alice L. Walton Foundation, the city of Bentonville is starting work on a massive overhaul of the sewer system.

Development was previously paused in several areas of town due to concerns about sewer capacity. Now, developers can start building again, but with a catch. 

The water utility and developers will be working on their respective projects at the same time, but new buildings can’t be occupied until the relevant sewer upgrades are completed. 

Bentonville Ballroom, a 2,500-capacity concert venue proposed for downtown, is one example of a project that was delayed due to capacity concerns, according to Water Utility Director Preston Newbill. It’s now moving forward and recently received initial approvals from City Council and the planning commission.

An in-depth study completed by consultants last year detailed Bentonville's sewer troubles.

At the simplest level, the pipes that carry sewage to treatment plants are too small to handle recent and future growth.

The sewer system is divided into five "basins," which are essentially neighborhoods of the sewer system. 

As a result of the study’s findings, development was paused in the Shewmaker Basin (shown in purple), South Lift Station Basin (shown in green) and Town Branch (shown in blue).

The consultants identified projects that needed to be completed immediately and suggested additional upgrades over the next 20 years. However, the city plans to complete those projects within 10 years instead. Newbill said accelerating the timeline would reduce overall costs.

“It reduced some of the costs, because there's 10 years that we're not going to see inflation on,” he said.

Anticipating the financing deal, the water utility started hiring engineering firms last year to complete pre-construction design work for anticipated sewage projects.

The city will accept bids for the first project financed by the $239 million deal starting April 14.  

The project includes replacing over one mile of aging 12- and 18-inch sewer mains with new 24-inch pipe in the Shewmaker Basin.

The water utility’s Capital Improvement Plan documents posted online show the status of future projects and what they’re expected to cost. 

The water utility also intends to spend more money studying the sewer system. There have been two core limitations with the work done by consulting firms to date:

1. One basin has not been studied at all.

The major study used to identify necessary projects covered four out of five sewer basins. The Southwest Basin, where much of Bentonville’s growth has been concentrated in recent years, was not included. 

Based on preliminary in-house calculations, Newbill said he thinks “we're going to have some issues there, and we're going to have to create some projects.”

2. Only the biggest pipes have been studied. 

For the most part, the studies done to date have focused on pipes 12 inches and larger. These are the highways of the sewer system, but the vast majority of pipes are much smaller. Further study could reveal a need to replace, repair and upgrade smaller lines, too.