The regional tunnel system is a critical component of the Clean Water Plan (CWP), which was adopted to meet the requirements of the Federal Modified Consent Decree and improve and protect the water quality of the region’s streams and rivers.

No, the tunnel system is adding new conveyance capacity to deliver combined sewage flows during wet weather events to the ALCOSAN wastewater treatment plant for treatment. The existing municipal and ALCOSAN sewers will continue to be utilized to transport sewage to the ALCOSAN wastewater treatment plant.

The new tunnel system is designed to last for at least 100 years. Operation and maintenance staff from ALCOSAN will be responsible for maintaining it. The tunnels will be accessed for maintenance via the access shafts.

Capturing “all” the overflows would not be affordable for the region. The tunnel system is configured and sized to capture enough of the combined sewer overflows to meet water quality objectives. The size of the tunnels was established in collaboration with the regulatory agencies.

The Clean Water Plan and the tunnel system is not intended to stop existing flooding conditions in the communities. The primary goal of the CWP and the tunnel system is to improve and protect the water quality of our rivers and streams.

Subsidence is not a concern along the ALCOSAN tunnel alignment because the tunnels will be located deep in bedrock.

ALCOSAN is a ratepayer funded authority and most of the CWP costs will need to be borne by the ratepayers. ALCOSAN’s rate strategy manages CWP cost impacts to ratepayers by implementing multi-year rate increases through 2036. ALCOSAN’s Board of Directors implemented a 7.0% annual rate increase for 2022 through 2026. ALCOSAN acknowledges the impacts of rate increases on low-income households and has increased the Clean Water Assistance Fund to $40/quarter. More information on the Clean Water Assistance Fund can be found at dollarenergy.org.

Sites will be restored to the existing condition at a minimum but may also be improved. Limited above ground facilities will be required as ALCOSAN will use the sites mostly to access the shafts and regulators via hatches and covers. As the design and construction of each tunnel progresses, ALCOSAN works with the community to determine potential opportunities for site enhancement following construction, which may include a paved surface or a cleared site for a greenspace.  

The new tunnel system must be constructed near existing sewers pick-up points to capture combined sewer overflows. This is a key factor in deciding on location of the proposed facilities. Other decision factors include environmental studies and geotechnical investigations.

Email ALCOSAN at ORT@alcosan.org with questions or comments about the regional tunnel system, including the Ohio River Tunnel.