Utility Master Plan yields planning software, recommendations for Siler City

The Siler City Board of Commissioners received an overview Monday of the town’s current and future water and wastewater needs, as well as recommendations for the future.

The presentation during the board’s Monday meeting was a result of the Chatham County Water and Wastewater Utility Master Plan, a collaborative effort between the county and the municipalities, to outline current and future needs as the county grows.

The county entered into a contract with Hazen & Sawyer in April 2018 for the project, which included collection and analysis of data in collaboration with representatives from each governing body and staff. The consultants then used that information to determine the near- and long-term demands for water and wastewater, created water treatment and wastewater alternatives and subsequent recommendations from those alternatives. The company also created an “update-able dashboard data management tool” that all the participants may use while considering how best to move forward with supplying water and wastewater needs for residents and businesses based on 50-year projections.

According to the project summary, Siler City is nearing its capacity for its water and wastewater needs. The town’s 4 million gallon per day (MGD) water plant and wastewater plant are operating at near capacity since the addition of Mountaire on the system. The consultants noted that adding a user at the Chatham-Siler City Advanced Manufacturing (CAM) Site would push the system beyond its current limits.

The group offered several alternatives including transferring 1 MGD of water from Chatham County, a collaboration already in discussion between the two; purchase capacity from Sanford’s water treatment plant; and/or expand the existing water treatment plant. When discussing the expansion of the current plant, the consultants noted that the water available to fill the reservoirs may not be sufficient for long-term needs. One suggestion was to install a wastewater discharge, the processed wastewater that currently discharges into the Rocky River, above the reservoir in order to build supply.

The group provided alternatives for expanding wastewater capacity as well. This included a land application facility near Mountaire or the CAM site, expanding and improving the existing wastewater treatment facility, a project the town is currently preparing to engage, and purchasing capacity from Sanford’s Big Buffalo wastewater treatment plant.

The group’s final recommendations for water capacity includes the town finalizing its contract with Chatham County for the 1 MGD water connection, evaluate expansion of the existing water plant, evaluate the benefit of a wastewater discharge upstream of the reservoir, and work to reduce the per capita demand for water — noting that Siler City residents use an average of approximately 136 gallons of water per day per resident, while a reasonable average for water use would be 100 gallons per day.

The group recommended the town continue working on the expansion of the wastewater treatment plant and work on the current sewer lines to prevent infiltration and inflow.

To assist the town in its deliberations on how to fulfil anticipated water and wastewater demands, the company created software that includes modelling to show, in real time, demand projections, all the alternatives provided, the estimated costs of each alternative, as well as the ability to see how different start dates would impact the ability for the town to meet demand. For example, if the town is able to have residents and businesses conserve water, staff can change that information in the system, instantly updating the modelling for demand.

While Hazen & Sawyer only presented the information to Siler City officials Monday night, it will share similar information with Pittsboro and Chatham County at future dates.