Parks!: Making the world better one municipal sewage system at a time

By Alec Harris — Aug. 6, 2013 at 11:19am

Municipal sewage cases are hot these days at the U.S. Department of Justice, Environment and Natural Resources, Environmental Enforcement Section. Across the country, DOJ attorneys are filing—and settling—municipal Clean Water Act (CWA) cases against cities. These cases aim to improve performance of municipal sewage systems. A new solution cropping up in settlement agreements may change the landscape of urban life and environmental enforcement.

NYC_scaravelloThe Problem
Many older, East Coast sewage systems combine stormwater runoff with “sanitary” (i.e. human-waste) sewage. During periods of moderate to no rainfall, a multi-step process effectively treats this wastewater mixture. Bacteria do the heavy lifting in this process, breaking down undesirable elements and allowing for clean discharge into local water bodies. However, the bacteria work slowly. When stormwater floods the system, treatment bacteria can’t keep up: Sewage overwhelms the treatment process and untreated sewage overflows in the system. In the business, this problem is known as a “combined sewer overflow” or “CSO.”

A CSO presents a city with three unappealing choices: (1) skip the bacteria and discharge dirty sewage into the water body, violating the city’s CWA permit; (2) dump untreated sewage along the way to the treatment plant to relieve volume, violating the CWA for discharge without a permit; or (3) do nothing and let sewage back up in basements around the city (known colloquially as a “basement backup”). In practice, most cities with CSO troubles end up doing a bit of all three.

The Environmental Justice Problem
Often, these harms are not distributed evenly. Instead, many cities follow the path of least political resistance and disproportionately impose dirty discharges, sewage dumps, and basement backups on low-income and minority communities (sometimes known as “EJ communities”).

The “Grey” Fix and EJ Issues
The old fix for CSOs was “grey infrastructure”—giant storage tanks, typically built underground, to hold overflow until the storm passes and the bacteria catch up. These tanks are very expensive. To pay for them, cities increase their utility rates. In so doing, cities again hurt EJ communities, who struggle to pay higher rates.

The “Green” Fix
A relatively new idea is to install “green” spaces in the city—lawns, parks, rooftop gardens—which absorb stormwater before it flows into the system. This solution is a lot cheaper than giant underwater storage tanks, meaning smaller rate increases for low-income communities. It also has some nice “co-benefits”:

Green Infrastructure, Environmental Justice, and Economic Redevelopment
We’ve already seen how EJ communities can get the short end of the stick when a city struggles with CSOs, and when it fixes the problem using traditional grey solutions. Green infrastructure projects can turn the tables beyond preventing inequitable distribution of environmental harms and reducing rate increases. In particular, by prioritizing development of green infrastructure in EJ areas, cities can bring resources and green spaces to communities that have been neglected in the past—all while working to solve the their CSO problems. Sometimes, this green infrastructure work even aligns with preexisting economic redevelopment plans. For example, in one recent Consent Decree, a city agreed to develop green infrastructure using EJ properties already owned by the local economic redevelopment authority. In so doing, the city accomplished both its economic redevelopment and environmental goals, all while helping EJ communities.

While green sewage infrastructure is unlikely to be the complete solution in CSO cases, it brings a welcome infusion of innovation, cost-cutting, and equality to the too-oft steel-and-cement mindset of modern municipal sewage. In a phrase: Amen to parks!

*Thanks to Kathryn MacDonald, Senior Trial Attorney, Environmental Enforcement Section Environment and Natural Resources Division, U.S. Department of Justice for her insight on this matter.