HH/SG EQ Tanks & Pump Stations
SD1 is building new equalization (EQ) tanks and pump stations in Highland Heights and Silver Grove, beginning a new era of smart-sewer management in Northern Kentucky that will significantly reduce the cost of complying with federal Clean Water Act regulations.
The two tanks, which will be used to hold mostly storm water, will eliminate about 20 million gallons of typical-year sanitary sewer overflows (SSOs), and will do so at a price tag well below what traditional overflow mitigation would cost.
“We’re going to make our sewer system smarter,” said SD1 Executive Director Adam Chaney. “We can no longer afford to simply build bigger and bigger pipes and wait for them to become overwhelmed by larger and larger storms.”
The first step toward smart sewers happens long before any work begins in the field. Working with its Updated Watershed Plan partner, Hazen and Sawyer, SD1 ran thousands of scenarios using artificial intelligence software to accurately predict what will happen throughout Northern Kentucky’s sewer system under various storm simulations.
The results of that work provided a blueprint – which SD1 is calling Clean H2O40 – for the most effective and affordable approach to mitigating sewer overflows. The new EQ tanks in Highland Heights and Silver Grove will be the first projects constructed under the new Clean H2O40 plan.
How EQ Tanks Work
The new tanks will ultimately use flow meter technology to signal the sewer system to store excess flow during storm events until downstream capacity is available. Once a storm has passed, the system will gradually release flow back into the pipes for transport to a treatment plant. This will minimize the risk of increased volume overwhelming the system and causing sewer overflows.
Chaney compares the technology to smart traffic lights during rush hour. As more and more cars begin to congest the road, traffic lights can be used strategically to keep things moving. SD1 will apply the same logic to Northern Kentucky’s sewer system, and the Highland Heights/Silver Grove EQ tanks are a step toward system-wide coordination – storing flow in tanks, pipes and other structures across the region.
“This new strategy is anticipated to significantly lower project costs and associated revenue needs by hundreds of millions of dollars over the next 20 years. In addition to maintaining sewer rate affordability, the reduced overflow mitigation costs will allow SD1 to address system expansion required to support the local economy,” Chaney said.
Amended Consent Decree
Under the terms of an amended consent decree with the Commonwealth of Kentucky and the US Environmental Protection Agency, SD1 must completely eliminate all typical-year sanitary sewer overflows by the year 2040. The system experiences about 115 million gallons of SSOs in a typical year. The agreement also requires SD1 to recapture at least 85 percent of combined sewer overflows by 2040.
Chaney said the Highland Heights and Silver Grove tanks – which will be located about a mile apart on Rt. 8 – will combine to hold about 3 million gallons when full and will help reduce about 17 percent of the region’s typical-year SSOs. While the tanks will have flow of mostly storm water in them 3-4 days per month, they should only fill completely once during a typical year.
The tanks are expected to be completed by December 2021 for an estimated cost of about $10 million.
“We’re going to use storm water storage in combination with smart sewer management to improve our system today and into the future,” Chaney said. “This new approach, along with the recent nearly 15-year extension on our consent decree deadline, will make it possible for SD1 to mitigate system overflows, improve water quality and public health, and continue supporting the economic vitality of our region without over-burdening ratepayers.”