Sewer Constraints May Force Tough Development Choices for Wilton Officials as Town Engineer Makes Case to “Hold the Line”

Wilton’s projected sewer demand now exceeds its contractual limit with Norwalk, even after factoring in anticipated savings from repairs still in progress — leaving the town facing difficult choices about capacity for future development.

Department of Public Works (DPW) Interim Town Engineer Steve Santacroce was the keynote speaker at Wilton’s Water Pollution Control Authority (WPCA) meeting on Wednesday, Oct. 14, where he presented the case for protecting capacity for existing residents and businesses, highlighting an option to “hold the line.”

WPCA members praised the presentation but did not explain how the authority would proceed with future sewer applications. Questions from GOOD Morning Wilton about what protecting capacity would mean in practice remained unanswered as of press time.

In his presentation — titled Sewer Capacity and Development in Wilton: Why development in Wilton is dependent on sewer capacity and our contractual limit with Norwalk — Santacroce traced how Wilton’s approach to estimating and managing sewer demand has evolved in recent years, culminating in last month’s revelation that Wilton’s sewer flows are now projected to exceed the town’s 650,000-gallon-per-day contractual limit with Norwalk.

Actual flows remain below that limit. The projection includes demand from projects under construction, approved and pending applications, reserves for existing properties and anticipated reductions from sewer repairs.

The presentation was designed to make the WPCA’s challenges more easily understood by residents and observers — and more specifically, to demonstrate how limited capacity constrains development.

“My objective for the presentation is to provide a clear overview of the sanitary sewer system in Wilton, where we stand today with our overall sewer capacity, and why it matters in terms of new development in town,” Santacroce began.

“Most residents never think about sewer capacity, but it’s one of the most important factors in local land use,” he said. “Where there is sewer available, higher density development is possible… That makes the remaining sewer capacity a scarce public resource that must be managed carefully.”

Calculations, Assumptions and Policies Explained

Santacroce’s presentation offered a simplified explanation of the worksheet DPW regularly uses to update the WPCA on town-wide sewer flows. The worksheet has been closely scrutinized and refined in recent years to ensure Wilton had adequate sewer capacity to approve new allocations without exceeding the Town’s contractual limit — but the latest calculation leaves no additional capacity theoretically available.

Santacroce explained the Town’s latest projected sewer flow of 650,811 annual average gallons per day (gpd) now exceeds the 650,000 bpd contractual limit. He noted, however, that the calculation uses a baseline of 550,000 gpd — the highest annual average in the past four years and higher than the current average of 484,000 gpd.

However, the 650,811 calculation reflects expected savings from repairs still in progress to reduce inflow and infiltration (I&I), while adding reserves for vacant buildings and other buildings that could come online.

The calculation reflects projected demand under the town’s planning assumptions; actual sewer flows remain below the contractual limit.

Santacroce also explained other factors that come into play, including:

• The WPCA’s rationale behind the assumption of 65-gallons-per-person-per-day it uses to estimate sewer flows from multifamily developments — a less conservative assumption than many other communities (often with their own treatment plants) typically use. It’s also less conservative than health department standards for residential septic systems.

• The WPCA’s adopted policy for prioritizing available sewer allocations: first to existing businesses — like ASML, whose expansion in Wilton has significantly increased its sewer allocation since 2024 — followed by Wilton Center, transit-oriented development, and Danbury Rd.

“Protecting Capacity”: Making The Case

Santacroce noted that the information in the presentation was “not new, but a summary of what has been presented in previous meetings.”

What was new was a more explicit articulation than in prior meetings of “the case for protecting remaining capacity” — highlighted by the option labeled “Hold the line.”

“Protecting the remaining sewer capacity for existing businesses and residents is of utmost importance,” Santacroce said.

To make the case, Santacroce focused on the sewer demand from new multifamily residential developments, citing two key points shown in the chart above:

• 60% of Wilton’s “new” sewer flow comes from multifamily projects. Santacroce said multifamily developments account for roughly 146,000 of 242,000 gpd from new projects, i.e., under construction, approved and pending applications.
• A large multifamily development with more than 200 apartments would typically be allocated about 25,000 gpd, which Santacroce said is “about 4% of Wilton’s entire limit.” [Note: Santacroce cited 131 Danbury Rd. (208 units) as an example. DPW’s spreadsheet calculates the theoretical flow for 131 Danbury Rd. at 21,522 gpd, or 3.3% of Wilton’s contractual limit.]

Santacroce went further in his comments about multifamily developments.

“Each large apartment building uses capacity that can’t be reclaimed once it is built,” he said, adding that a strategy to seek more capacity from Norwalk “would likely draw more large apartment applications and be used up quickly.”

The presentation also identified recovering capacity through leak repairs and expired allocations as an option, while noting that doing so takes time and investment.

In his final statement, Santacroce repeated his earlier point about “protecting” capacity. “Wilton must remain committed to its sewer priority policy to protect existing businesses and residents,” he said.

Priority 1: ASML

Along with new apartments, Wilton has prioritized significant new sewer allocations to support ASML expansion in recent years.

Since 2024, the WPCA approved 67,955 gpd in supplemental sewer allocations for ASML, including 48,000 gpd at its 20 Westport Rd. facility, 18,883 gpd at 77 Danbury Rd., and another 1,072 gpd for a clean room at 20 Westport Rd.

Such an increase is substantial. For context, ASML’s increase is equivalent to the combined allocations (67,629 gpd) of four multifamily developments in Wilton:

• 141 Danbury Rd.: 171 units at Riverside Wilton, 22,451 gpd
• 15 Old Danbury Rd.: 206 units adjacent to the Wilton train station, 25,700 gpd
• 64 Danbury Rd.: 116 townhouses, 11,438 gpd
• 19 Cannon Rd: 70 units adjacent to the Cannondale train station, 8,040 gpd

And now, ASML has just announced plans for further expansion in Wilton. The company has not indicated whether its expansion will require additional sewer resources.

Protecting In Practice

WPCA Chair Toni Boucher praised Santacroce’s presentation as “an excellent summary and a great document for the public to be able to access.” WPCA members Ross Tartell, Kim Healy and Rich McCarty echoed the praise, though no one expressed any views about the implications for the WPCA or how the authority would proceed with future applications.

With projected demand theoretically already exceeding the contractual limit, it is unclear what “remaining capacity” the town could protect or how the WPCA would apply that approach.

GOOD Morning Wilton reached out to Boucher and Santacroce immediately after the Oct. 14 meeting for additional insight on what “protecting remaining capacity” would mean for the WPCA in practice, and specifically whether it was meant to signal that the WPCA would not consider new applications at this time. As of press time, neither has responded to this question. GMW will update this story if any response is received.

Boucher did reply to GMW‘s question about whether she was aware of any indication ASML might request additional sewer allocation as part of its new expansion plans — though she did not answer the question directly.

“We are in regular communication with ASML and discussing their needs on an ongoing basis,” she wrote in an email to GMW.

Official Request to Norwalk

In the meantime, town officials submitted an “official notification” to Norwalk that Wilton’s latest projections exceed the contractual limit.

GMW requested and reviewed a copy of the letter, which was sent by mail and email to Norwalk Chief of Operations and Public Works Vanessa Valadares and Mayor Barbara C. Smyth on Sept. 28.

The letter also formally requested another meeting with Norwalk officials “and respectfully asks that the City reconsider its previous denial of our request for additional sewer capacity.”

More WPCA News

• I&I Phase 2: Christine Kurtz, the Town’s engineering consultant from Wright-Pierce, reported that two qualified bids were received for the second phase of sewer rehabilitation work that was planned and budgeted in 2025. Paperwork for the lower bid, from a contractor Wilton hired for previous improvements, is being prepared for WPCA review in November. The work will reduce “inflow and infiltration” (I&I) which creates excess flow in Wilton’s sewer system. The repairs could potentially reduce sewer flows by 172,000 gpd — a number already reflected in Wilton’s capacity calculations.

• Kimco Phase 2: Following discussion in the Sept. 23 WPCA meeting regarding Kimco’s Phase 2 plan for 15-21 River Rd., Santocroce said the town sent its review letter to the applicant but had not received a formal response yet. He said he expects a response by the WPCA’s November meeting.