Green First Update: Reducing Overflows at the Source
ALCOSAN has been working with our municipal partners to create an affordable and adaptive Clean Water Plan to meet the requirements of the regulators, improve water quality in our rivers and streams, spur continued economic development, and advance the quality of life and our environment in the region.
Wet weather overflows are caused by excess stormwater and groundwater entering the region’s sewer and stormwater system during and following rain and snow events. As we pursue solutions to the overflow problem, it’s useful to remember a simple model that illustrates the options for handling storm water and sewage flows:
• First, you can stop flows from entering the system in the first place;
• Second, you can move it through the network of pipes;
• Third, you can hold it; or
• Four, you can treat it.
Taking advantage of the right combination of these sewer and stormwater management methods to design an efficient and sustainable solution that’s right for our region is the goal.
Our first step is to stop flows at the source, which is why we are using green infrastructure (and we will continue to expand upon those efforts), as well as inflow and infiltration control projects that sustainably restore natural watershed features and our existing wastewater collection system.
ALCOSAN’s partnerships with our customers, the municipalities, have been a crucial part of our work. Together, we helped develop the original plan, and we continue working together to develop new strategies and procedures to reduce overflows. One major key is: how much stormwater can be diverted via green infrastructure, which will help us determine how to right-size treatment.
Regional System Management
One step in the Clean Water Plan has been to develop a regional approach by having ALCOSAN assume responsibility for the multi-municipal trunk sewers and wet weather facilities. We have met with all of the impacted municipalities to begin discussions of the transfers, and are proceeding with video inspection televising of the pipes. This project, once completed, will significantly reduce maintenance and operations costs for the municipalities, while allowing rehabilitation and other decisions to be made in the interest of the best overall system performance for the entire region.
Project Status and Path Forward
ALCOSAN and its 83 customers – the municipalities we serve – have already implemented numerous flow reduction projects and are identifying many more. In addition, ALCOSAN will soon launch a new source reduction funding program to support municipal partners’ efforts.
To advance our understanding and assist our partners, ALCOSAN has estimated flows from our municipal customers. This will assist our coordination of responsibilities, as well as comply with a June 2015 regulatory agency information requirement.
On January 31, 2016, ALCOSAN provided the agencies with the estimates of the flows sent to ALCOSAN by each municipality, and how much flow reduction would be needed after implementing priority upgrades of the treatment and conveyance system, including the transfer of the large multi-municipal sewers.
Regulatory agencies plan to require reductions in the amount of stormwater that customer municipalities send to ALCOSAN. Setting flow targets is the next step to making that happen, with ALCOSAN assisting its municipal partners in determining those targets.
ALCOSAN and its customers are still discussing the best way to do this. Flow targets are due to be provided to the regulatory agencies in January 2017.
For more information, contact ALCOSAN’s Public Information Officer Jeanne Clark at Jeanne.Clark@alcosan.org.