It’s well known that rain gardens are great for infiltrating stormwater but people may not realize that they also help destroy common stormwater pollutants. Several studies have found that rather than accumulating pollutants in their soils, rain gardens tend to biodegrade them instead. One study (LeFevre et al., 2011) investigated petroleum hydrocarbon levels in 58 rain gardens in Minneapolis, MN representing a wide range of sizes, vegetation types, and contributing area land uses. The researchers found that petroleum hydrocarbon levels were well below regulatory limits in all the rain gardens sampled. And a tip for future rain garden installers, rain gardens planted with more robust vegetation with deeper roots did a better job at breaking down pollutants than those planted with only turf grass.
A rain garden’s ability to biodegrade pollutants is in contrast to what happens in more conventional stormwater management structures like retention ponds. Retention ponds are often installed with larger developments to receive a large volume of stormwater from impervious areas (ex. houses and roads in a subdivision, roof and parking lot of a Home Depot). Other studies (Van Metre et al., 2009; Van Metre et al., 2000; Kamalakkannan et al., 2004), found that pollutants like PAH’s (polycyclic aromatic hydrocarbons), a type of petroleum hydrocarbon, accumulate in the sediments of stormwater retention ponds. This creates a very expensive maintenance issue for retention pond owners when the time comes to remove and dispose of built up contaminated sediments.
Side note – stormwater can pick up PAHs from dust on pavements treated with coal tar sealants which are commonly used on parking lots, driveways, and playgrounds (but they have recently been banned from use on State and local highways in CT).
On my drive home last week I saw two of my neighbors walking their dogs. One of the dogs had just done his business and the owner dutifully scooped it up with a doggy doodie bag dangling from the dog’s leash. Excellent, I thought, he knows that dog poop left on the street can be carried by stormwater into our storm drain and then pollute our waterways with bacteria. As a water quality educator, I was pleased to see the “scoop the poop” message was getting out.
However, my neighbor then proceeded to drop the doodie bag directly into the storm drain! So, there is still work to do. Once you scoop it, you need dispose of it properly – either in the garbage or flushed down the toilet (minus the plastic bag). Not carry it directly to the storm drain.
This has gotten me to think more about how we educate the public about the impacts of common everyday activities on our lakes, streams and rivers. Under our new state stormwater management regulations (a.k.a, the MS4 permit) towns are required to educate their citizens on the impacts things like pet waste and fertilizer have on our waters when transported to our storm drain system. However, if towns are going to invest/spend their limited time and resources on public outreach, it makes sense that they ensure they are as effective as possible at conveying the whole message, while also keeping it simple.
Haddam – As the state gets wetter, Connecticut cities and towns have little choice but to take better control of the water that flows over streets, parking lots and fields from rainfall and snowmelt.
“There are two drivers related to stormwater,” said David Dickson, faculty member of the UConn Center for Land Use Education and Research (CLEAR). “One is climate change. New England is seeing more rain and more intense rainfall events. The other is the MS4 general permit, which became effective in 2017.”
Dickson, speaking at a March 22 symposium sponsored by the UConn Climate Adaptation Academy, explained that MS4 — the shorthand term for the new state regulation for how municipal stormwater is managed — now requires cities and towns to reduce nonporous pavement on streets, sidewalks and parking lots. It also requires they establish “low impact development” practices as the standard for new construction. The state regulation is the result of a federal mandate under provisions of the Clean Water Act requiring gradually stricter rules to curb pollution.
“Towns have to enter into a retrofit program to reduce impervious surface areas by two percent by 2022,” Dickson said. “LID now has to be the standard for development. You can’t just say it’s too costly. This is going to change how we think about site development in this state.”
The third workshop in a series on the impacts of changing weather patterns on local land-use practices, the symposium drew about 50 municipal officials from around the state. It was presented at the Middlesex County Extension Center by the Climate Adaptation Academy, a partnership of CT Sea Grant, CLEAR and the UConn College of Agriculture, Health and Natural Resources. The Rockfall Foundation co-sponsored the event.
Overall, the purpose of the session was to educate local officials about “what works and what to watch out for to ensure success” when it comes to implementing low impact development, said Tony Marino, executive director of the Rockfall Foundation.
Dickson, the first of the four presenters, explained that with increasing amounts and intensity of precipitation, the impacts of unmanaged stormwater carrying road and agricultural pollutants into the environment are increasing.
“Stormwater is the top source of water pollution into Long Island Sound,” he said.
In the 1990s, low-impact development techniques emerged including “green roofs” covered with planted beds to absorb rainfall, grass swales to replace curbs and gutters, rain gardens and bio-retention areas with trees and shrubs situated to absorb runoff, and permeable pavement that allows water to infiltrate into the soil. That allows the soil to capture pollutants and groundwater to be recharged.
Since then, LID designs have been used at several sites on UConn’s main campus and in the Jordan Cove housing development in Waterford, among other locations around the state. While at least one-third of towns in Connecticut have adopted LID techniques at various levels, Dickson said, the new regulation means all towns will have to commit to making them the standard practice because it’s an economical and effective way to comply with the requirement to curtail stormwater runoff.
“Towns will have to start thinking about where impervious cover drains directly into their stormwater system, and enter into retrofit programs to reduce impervious areas,” he said.
Michael Dietz, water resources educator with CLEAR, said that more than 20 years after they were built, the LID features in the Jordan Cove development are still working. Research shows significantly less runoff coming from the portion of the development with LID compared to the control section built with traditional design features, he said. The LID structures continued to function even when the homeowners failed to maintain the areas correctly, he noted.
“The take-home message is that LID mostly still works, in spite of what people do,” he said.
At the main UConn campus, Dietz said, LID has “become part of the fabric of the design” for all new construction since it was first used in the early 2000s. But over those years, there have been mistakes and lessons learned, he added. In one case, curbs were installed where they weren’t supposed to be so runoff ended up being directed away from a bio-retention area. In another case, the bio-retention area was poorly located on the way students took to a dining hall, creating a compacted path that reduced its effectiveness.
“We failed to factor in people,” Dietz said.
The area, he said, was redesigned with a footpath through the middle that still allowed for runoff capture.
In another example, a parking lot next to the field house covered with permeable concrete “totally failed” last year and was allowing for “zero infiltration.” The concrete was not mixed and handled properly, he said, and curing time was insufficient, among other problems. It has been replaced with pre-cast pervious concrete blocks. Other challenges include the need for regular cleaning of pervious pavement to unclog porous spaces.
“You neglect it, it costs you down the road,” Dietz said.
Giovanni Zinn, city engineer for New Haven, said the dozens of bio-retention areas, rain gardens, swales and pervious pavement areas installed around the city do require more planning and attention.
“But if you simplify your designs, the construction will be less costly and they’ll be easier to maintain,” he said. Overall, he added, maintenance costs are less costly than for traditional infrastructure.
He advised choosing low-maintenance plantings and involving local residents and community groups in the projects. Looking ahead, New Haven is planning to build 200 more planted swales to capture runoff in the downtown area and another 75 in other parts of town.
“The bio-swales are the first step in dealing with our flash flooding issues in the downtown,” he said.
David Sousa, the final speaker, is a senior planner and landscape architect with CDM Smith, which has its headquarters in Boston and an office in East Hartford. Instead of talking about development practices to minimize runoff, Sousa focused on “how to avoid it altogether.”
He advocated for compact urban redevelopment over “big box” stores with large parking lots. Not only does this give residents stores and restaurants they can get to on foot, by bicycle or mass transportation, “it also saves acres of green fields.”
“It’s being done in our communities,” he said, citing examples in Mansfield, Stamford and Middletown. “But it’s not being done enough.”
Redevelopment of urban areas, he said, creates communities that use fewer resources, which in turn is better for the environment.
“The carbon footprint of people in cities is so much less than those with suburban lifestyles,” he said. “With less vehicle miles traveled, there is less need for impervious parking surfaces, less stormwater flooding and less emissions. We need to think about ways to avoid using LID in the first place.”
Judy Benson is the communications coordinator at Connecticut Sea Grant. She can be reached at:email@example.com
CLEAR’s venerable, award-winning NEMO (Nonpoint Education for Municipal Officials) Program is embarking on a five-year program to assist Connecticut communities in complying with the state’s revised “General Permit for the Discharge of Stormwater from Small Municipal Separate Storm Sewer Systems,” or the MS4 permit. Stormwater runoff is a major source of flooding, erosion and water pollution in Connecticut’s waterways, and is expected to become even more of a problem as climate change progresses.
After much negotiation between CT DEEP, Connecticut municipalities and the environmental community, the MS4 underwent a significant expansion and enhancement this July. Eight new towns have been brought into the program, making a total of 121 (almost ¾ of all the municipalities in the state), and for the first time most state and federal institutions are also included. And, while the program remains organized according to its six “Minimum Control Measures,” there are important new aspects and requirements involving monitoring, maintenance of town properties, and “disconnecting” impervious areas through Low Impact Development (LID).
In the current economic environment Connecticut communities are struggling with a host of needs, and navigating the various aspects of the MS4 will be a challenge. In recognition of this, CT DEEP is funding NEMO to develop and implement a multifaceted support program that includes outreach, technical assistance, web tools and other resources. To list just a few:
MS4 “Circuit Rider”: a NEMO Extension Educator dedicated to the MS4 support program will conduct workshops, trainings and consultations with towns.
MS4 website: a website far above and beyond the typical regulation website is being developed, as an authoritative and detailed (but not wordy!) guide to MS4 implementation and home for special technical and mapping tools.
Webinar series: CLEAR’s webinar series will spin off a special NEMO/MS4 series highlighting different requirements of the regulation and approaches to meet them.
Mapping training: CLEAR’s Geospatial Training Program will provide training and tools to help communities meet the new mapping requirements of the permit.
Impervious Cover data: NEMO is working with an outside contractor to obtain high resolution impervious cover data, which will be an enormous asset to conducting the drainage area and impervious area analyses required in the permit.
The CLEAR Water Team (aka NEMO Team) is looking forward to this challenge, and in the process developing a whole new generation of stormwater outreach tools and resources. NEMO will be working with DEEP, regional Councils of Government, and both public and private sector organizations to tackle this issue so important to the health and welfare of the citizens of Connecticut.
Although UConn is in the midst of a pastoral setting in the quiet corner of northeast Connecticut, we sometimes have problems like a big city. This is because the buildings, roads, parking lots and sidewalks that make up the core of campus do not allow water to pass through into the ground. Instead, rainfall is directed into storm drains, and ends up heading towards either the Fenton River to the east, or Eagleville Brook to the west. All of the excess stormwater and pollutants that get picked up along the way cause problems with the aquatic life in these rivers. The CT Department of Energy and Environmental Protection has identified Eagleville Brook as impaired. UConn Extension’s Center for Land Use Education and Research (CLEAR) has been involved in efforts to reduce the impacts of all of these impervious surfaces on Eagleville Brook. Green infrastructure practices like bioretention, green roofs, and pervious pavements have been installed around campus to help restore a more “natural” hydrologic balance. A Total Maximum Daily Load (TMDL) has been established for the brook, with impervious cover as the “pollutant” (read more about this project at http://clear.uconn.edu/projects/tmdl). An interactive map tour with photos and videos is available online here.
With all of the changes taking place on campus, keeping track of the actual impacts of the green infrastructure implementation is not an easy task. Traditional water monitoring could be done, but this is very expensive and time consuming. Recently, UConn Extension Educator Michael Dietz at CLEAR created a unique system to estimate the benefits of the green infrastructure on campus. This tracking system uses real precipitation data from UConn, and estimates the amount of stormwater treated by each practice installed, given how big the practice is, when it was installed, and the condition of the practice. This allows for a running total of the volume of stormwater treated. Through June 2014, more than 42 MILLION gallons of stormwater have been treated! To put this in perspective, this is enough to fill more than 63 Olympic sized swimming pools!
This information is being used to track progress on the TMDL, along with other regulatory obligations between UConn and DEEP. Dietz plans to continue this tracking, along with other monitoring he and Jack Clausen perform on Eagleville Brook (real-time data available here).
Anyone who has been to the UConn campus in the last few years has likely noticed a lot of changes. Beautiful new and renovated buildings are remaking the campus. Along with those changes are a lot of more subtle changes that you might not notice – namely the integration of green infrastructure.
As discussed in previous posts, green infrastructure refers to using nature and natural processes to deal with infrastructure issues like stormwater. It includes such practices as bioretention/rain gardens, pervious pavements, and green roofs (among others). UConn has become a statewide and national leader in implementing these practices.
To highlight some of UConn’s efforts and demonstrate how to integrate these practices into an urbanized/urbanizing community, we created a virtual campus tour using Esri’s Story Maps tool in AcrGIS Online. (Story maps, by the way, are an extremely slick and easy way to bring your data or information to life in a geographic context. Definitely worth checking out.)