Consultants put $16.6M price tag on Norwalk wastewater consent order

NORWALK, Conn. — Updating Norwalk’s wastewater treatment as required by the Connecticut Department of Energy and Environmental Protection (DEEP) will cost an estimated $16.6 million over the next five years, consultants said Monday, adding that those expenses would be part of $53 million in improvements needed over the next two decades.

In May, Mayor Harry Rilling signed a consent order with DEEP, agreeing, in part, that the City would update its Sanitary Sewer Collection System Master Plan, and submit it to DEEP by Sept. 30. The $16.6 million would meet DEEP’s requirements.

“The Long-Term Recommendations target ongoing investment for the City’s sanitary sewer collection system assets to continue to maintain the health of the system, increase resiliency, and improve overall system performance.  These Long-Term Recommendations will be completed over the next 20 years with an estimated cost of $36.4MM,” Interim Chief of Operations and Public Works Vanessa Valadares wrote Thursday in an email to NancyOnNorwalk.

Consent order

Norwalk has dumped raw sewage and under-treated sewage into the Sound on multiple occasions because of specific inadequate mechanisms and can be reasonably expected to pollute state waters further given the system’s existing conditions, DEEP said in the consent order.

The order evolved from the City’s 2020 application to renew its wastewater treatment plant permit under the U.S. Environmental Protection Agency’s (EPA) National Pollutant Discharge Elimination System (NPDES), documents provided by DEEP show.

Norwalk agreed to eliminate the Ann Street siphon, described as “an unpermitted emergency overflow outfall” by the environmental group Save The Sound. The City must also “either provide primary treatment to a permitted sewage overflow outfall or eliminate use of that outfall within 10 years.”

DEEP renewed the five-year NPDES permit “with terms that were substantially similar to the prior permit” but responded to public concerns with the consent order, said Mat Todaro, an environmental attorney and a partner at Verrill Law Firm, at Monday’s WPCA (Water Pollution Control Authority) meeting.

The WPCA had already been planning to update its collection system master plan, Todaro said. Per the consent order, WPCA hired environmental engineering firm Brown and Caldwell, both for the master plan and for a facilities plan update expected by DEEP on or before June 30.

Recommendations

Eric Muir of Brown and Caldwell downplayed the Ann Street siphon issue, saying it doesn’t actually activate except in a 100-year 24-hour storm, “really pretty exceptional in comparison to other Connecticut municipalities.”

The Wall Street outfall activates at a two-year six-hour storm and an outfall at the plant activates during a one-year six-hour storm, he said. That’s when flows exceed the plant’s 30 million gallons a day capacity.

Norwalk needs to keep up its good practices, regular cleanings and sewer line inspections, Muir said. But new infrastructure on Hubbell Lane “would relieve a bottleneck in the collection system.”

The $5.4 million project would “relieve a hydraulic stress” and better send flows to the wastewater treatment plant, while mitigating Wall Street overflows, he said.

An engineering analysis would identify catch basins that “contribute high inflow (of stormwater) and are cost effective to remove,” Muir said.

Catch basin disconnections are estimated to cost $10.3 million.

A physical barrier to eliminate the siphon would cost $850,000.

Brown and Caldwell installed meters and found “the collection system really performed exceptionally well,” Muir said.

Authority funded by user fees

WPCA will “update its financial model to include the report recommendations,” Muir said. The expenditures are “generally in line with the normal asset renewals that are needed for a collection system of this size and of this age.”

“Norwalk is one of six (Connecticut) communities that have a combined system (that mix stormwater with sewage). And when you start comparing to greater New Haven, and MDC (Metropolitan District of Hartford), in Norwalk we’re really doing very well with during these large storm events,” said Norwalk Senior Engineer Ralph Kolb

“You continue to invest into the collection system and to the city’s assets, infrastructure. But as you make those improvements, the system continues to change. You have private laterals that may degrade, you have other pipes that start to get older,” Kolb said. “So the goal is to, you know, target the catch basins and continue to invest in the infrastructure to reduce long term SSOs (Sanitary Sewer Overflows) in the system.”

On Thursday, Valadares explained, “The WPCA is an enterprise fund, meaning that its costs and obligations are met through user fees which have remained consistent over time. In addition to a strong capital reserve, the WPCA recently developed a financial forecasting tool to assist with appropriately planning for infrastructure upgrades.”

Norwalk’s capital budget usually includes WPCA projects. The City borrows money at the best rates available given its Triple A bond rating and WPCA makes payments on the loans.

On Monday, Common Council Majority Leader Barbara Smyth (D-At Large) asked if the $53 million would be spread out evenly over the 20 years.

It will be “front-loaded early in the first five years,” Kolb replied. A $4 million project is in design and will go to bid next year.

There’s “some complexity” to Hubbell Lane and, “We’re looking to put a 60-inch sewer on Smith Street,” he said.

Valadares explained Thursday:

“The WPCA routinely evaluates City infrastructure and plans for any needed future upgrades and investments.  The WPCA’s efforts to enhance sanitary sewer collection system assets are continually ongoing and generally predate the development of the 2022 Collection System Master Plan.

“In addition, the Master Plan was designed to address various measures and projects that can reduce I/I {Inflow and Infiltration} throughout the system. The Master Plan also addresses sanitary sewer rehabilitation projects that would help to improve overall system performance. “The I/I project discussed at the meeting refers to a sanitary sewer rehabilitation project that is currently in design and centered around rehabilitation of Sammis Street and Bell Island pump stations and associated piping and a few other locations within the City.  The project was originally discussed by the WPCA Board at its September 20, 2021 meeting. The project cost is estimated to be $4MM and, because of shared objectives, has been incorporated into the Master Plan’s Long-Term Recommendations.”

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