I’ve been working to get more involved with the Urban Land Institute lately. During the 2016 Fall Meeting in Dallas I was able to connect with Katharine Burgess and Rachel MacCleery, both of ULI’s Center for Sustainability and Economic Performance. They were kind enough to allow me to help review and contribute to a report they were working on about the use of natural drainage systems in real estate that would eventually be called “Harvesting the Value of Water.”
The report, which was formally released in May of 2017, was made possible by a grant from the Kresge Foundation and was prepared with review and input from many ULI members and experts. I was glad to have a small role in its preparation.
The report first explains why stormwater management issues have recently become more visible. In the late 1800’s and early 1900’s cities in North America were just beginning to construct urban sewer systems. There were two competing approaches: a combined sewer system, which handled both sanitary sewage and stormwater runoff, or a two-pipe system that handled each in its own pipe. Several hundred cities constructed combined sewer systems to serve at least some portion of their area. These system can sometimes overflow during larger rains. These overflows are known as Combined Sewer Overflows or “CSOs.” CSOs discharge untreated sanitary sewage into area waterways, which is . . .um.. . not so good.
The Environmental Protection Agency (EPA) started working with cities with CSO issues back in 1994 and now many of them have entered into legal agreements with EPA and the U.S. Department of Justice to address them.
Initial plans to address CSOs called for large diameter tunnels to be constructed to store the mixture of water during rain events to reduce the number and severity of overflows. These projects had price tags of $4, $6, or $8 billion per city. Several cities figured out that using green stormwater infrastructure (GSI) to manage stormwater above ground at each building or site substantially reduced overall CSO mitigation costs. Some cities added the use of GSI to manage private property and public stormwater runoff volumes into their agreements with EPA. These programs require volume control to a larger degree than that typically required for merely floodplain management. So in some parts of the country, outside of Houston, the use of GSI is required.
In other parts of the country GSI is required by states and local governments to reduce stormwater pollution to estuaries or other waterbodies that don’t currently meet surface water quality standards. The Chesapeake Bay restoration effort is one of the largest examples.
The report also provides a good introduction to GSI techniques, such as green roofs, bioswales, rainwater harvesting, and rain gardens. Chapter 4 explains how smart GSI implementation can provide private real estate developments higher operating income, faster lease rates, higher occupancy levels, greater lot yields, green marketing benefits, and reduced drainage infrastructure costs.
Chapter 5 provides eleven case studies from around the country that illustrate how GSI has been deployed in various types of real estate development projects. The publication includes a profile of Stonebrook Estates, a 50-acre Houston-area single-family residential development case study. The development features a GSI system designed by Steve Albert, P.E., who was with Aguirre and Fields at the time. The balance of the site civil infrastructure – the potable water distribution, the sanitary sewer system, roadway paving, and general grading was designed by R. G. Miller Engineers, Inc. before I started working there.
bioswale with overflow structures for handling larger storms at Stonebrook estates. Photo credit: m. bloom
The last chapter summarizes the stormwater policy landscape and explains the range of methods used by the local governments to either allow, encourage, or mandate the use of GSI in land development. These methods can range from merely enacting a permissive regulatory framework that allows private project sponsors to use GSI when it makes good business sense (a bottom-up, market-based approach); to offering some permitting or financial incentives; or to enacting across the board mandates for stormwater volume controls and retention to achieve CSO mitigation or surface water restoration objectives (a top-down, regulatory approach).
I encourage folks to download the publication and check it out.