Wilmette $ewers: What Do the Numbers Show?

During the current discussion about Wilmette stormwater management, one point of contention is the cost.

The Wilmette Village Board has discussed implementing the Option 1: Storm Sewer Improvement to reduce westside flooding. The project would install a whole new system of storm drains, as well as miles of new storm sewers, and a new storm “trunk” to drain excess stormwater west into the North Branch of the Chicago River.

The estimated price tag is $77 million.

This post is my initial attempt to get some financial perspective on the matter. Although I don’t have enough data or financial expertise to do definitive number crunching, it seems worthwhile to look into general costs and benefits.

I’ve even tried to calculate total sewer spending for the past couple decades–in today’s dollars.

Comparison with Eastside Relief Sewer

First, for comparison, let’s consider the eastside relief sewer project, which has alleviated flooding east of Ridge Road. I found a Pioneer Press news article reporting that “Wilmette’s massive East Side sewer reconstruction” would cost $37.4 million–but the article was written in 1994.

In today’s dollars, that translates into a price tag of $60,782,066 million:

I found it difficult to track all expenditures for the eastside project. But the proposed westside storm sewer improvement doesn’t seem wildly different in cost.

So why is the eastside relief sewer generally considered a success, not a burden?

  • Sound Engineering: It was based on sound stormwater analysis and engineering.
  • Comprehensive Solution: It provided a comprehensive solution (including berms, flow restrictors, storm trunk, and pipes).
  • Attacked Problems: It achieved the EPA goal of reducing combined sewer overflows. It also met the demands of local residents, by reducing basement flooding, and stormwater damage.
  • MWRD Support: It linked into MWRD’s TARP system (paid for by every taxpayer in Chicagoland), thus leveraging local Wilmette investments.
  • InterGov Coordination: On a smaller scale, it relied on state grants for areas like Sheridan Road (a state-owned roadway).
  • Phased Construction: It was constructed in phases, combining sewer work with road construction to reduce costs.

Takeaways for the Separate Storm Sewer

Many of these principles could be applied to the westside project:

  • Sound Engineering: The Option 1 westside storm sewer upgrade is based on sound engineering analysis, including recommendations from at least three engineering studies, from as early as 2009.
  • Comprehensive Solution: Option 1 would add a major new storm “trunk” to carry stormwater to the North Branch of the Chicago River. Recommended “add-ons” could increase impact (e.g., flow restrictors, detention systems, rain gardens, inflow/infiltration reduction).
  • MWRD Support: The village should try to get financial help from the MWRD. (Informally, I’ve heard that an MWRD grant of $8K might be possible.)
  • InterGov Coordination: It would be important to determine if any state/county grants would be available, or if it’s possible to coordinate with state/county road projects.
  • Phased Construction: The Wilmette Director of Public Works and Engineering also confirmed (at a Roads & Water Fund meeting) that Option 1 could be planned in phases, combining sewer and road construction to cut costs.

Perspective on Total Wilmette Sewer Spending

While hunting for information on Wilmette sewer financing, I received a spreadsheet of Wilmette Sewer Expenditures, for 1992-2015 (a 23-year timeframe), provided by the Wilmette Department of Public Works. To get some insight into the financials, I adjusted the numbers for inflation and sorted the expenditures by type.

In today’s dollars, Wilmette spent a total of $105,608,330 on sewers.

It seems that three types of expenditures were posted:

  • Westside Studies = $739,506 *
    I was surprised to discover that Wilmette taxpayers have now spent three quarters of a million dollars on studies–all on westside flooding and sewers. That seems like more than enough to figure out what’s going on.
    * NOTE: Since this post was published, the Wilmette Village board authorized another $120K to complete a “value” study of Option 1, bringing the grand total for westside studies to approximately $859K.
  • Maintenance = $15,487,494
    Wilmette spends up to $1.5 million per year to inspect, televise, reline, repair, and replace damaged or backpitched pipes and manholes. This is expensive and does nothing to increase capacity. But with aging infrastructure, options are limited. The village already uses relining as a cheap alternative to replacing pipe; perhaps new technology and materials can help reduce costs in the future.
  • Upgrades = $89,381,330
    Investments in sewer upgrades actually increase capacity and reduce flooding and/or sewer backups. Projects were distributed across the village. Upgrades include the West Park Storage Tank and eastside relief sewer, as well as many street-by-street upgrades to larger diameter pipes.

A glaring omission in this financial spreadsheet is expenditures for community education and village-wide initiatives to develop a comprehensive response to the threats posed by urban flooding.

Comparison with Neighboring Communities

At the September 19 Long-Term Capital Planning meeting, the information packet included a slide about sewer spending in neighboring communities.

Based on the numbers presented, it appears that the westside Option 1 Storm Sewer Improvement would yield average results per dollar invested:

A caveat is that the chart above is limited to an analysis of the value of structures completely cleared of flooding during “100-year” rain events. But during the meeting, community residents made it clear that there are many additional costs associated with flooding.


For more information on the Option 1 Storm Sewer Improvement, see the Village of Wilmette, Separate Storm Sewer System Stormwater Management Report, by Christopher B. Burke Engineering (Jan 2015), pp 1, 7, 9-10.

For one of the earliest recommendations on adding a westside storm sewer trunk (or even replacing the entire westside storm sewer system!), see the Village of Wilmette Separate Sewer Study, by MWH Americas Inc (Sept 2010), pp 8-9, 16, 48, 68.

For data and recommendations related to the westside sanitary sewer (which suffers from stormwater inflow/infiltration), see the Village of Wilmette, Flow Monitoring Report, by RJN Group (April 2014), pp 15-17.

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