SOUTH PORTLAND — As the city continues to move ahead with environmentally sustainable initiatives above ground, Community Planner Steve Puleo is charting the progress made underground.
After establishing new regulations and encouraging best management practices and low-impact development to improve how stormwater is managed, progress is now trackable.
“We’re trying to green the city through development,” Puleo said last week.
The idea, he admits, seems counterintuitive to sustainability.
The reason is, for the most part, South Portland is built out, in terms of development, said Fred Dillon, who is the city’s stormwater program coordinator.
In 2009, the city upgraded its ordinance to better manage stormwater with new development and redevelopment. The move was made to remedy five impaired urban streams and filter pollutants out of stormwater before it runs through watersheds and eventually empties into Casco Bay.
“There aren’t many new green spaces and undeveloped land left in the city,” Dillon said Thursday morning. “Most of what happens is redevelopment.”
In most cases of redevelopment, for example, “most of the original development happened 15, 20, 30 years ago when we didn’t have the types of stormwater management systems that provide the kind of treatment required today,” he said.
“We look at every redevelopment as an opportunity to (install) these state-of-the-art systems,” Dillon added.
Puleo said it’s about initially holding back a certain amount of runoff, in order to siphon out pollutants. By slowing the speed at which stormwater filters through the system, built-in infrastructure – wetlands filtered by gravel, stormwater treatment drains, and subsurface sand filters – are able to extract and trap pollutants.
The old saying rings true, Puleo said: “The solution to pollution is dilution.”
Because, for example, an impervious surface like asphalt doesn’t allow stormwater to soak into the ground, the intention is to reroute the stormwater into areas where it can be filtered in a more natural process.
In a significant rainfall event like what occurred Wednesday, Sept. 30, where parts of greater Portland were flooded and pollutants were carried into the sewer systems, South Portland’s updated stormwater systems were able to slow down the flow of water in order to remove a higher percentage of wastewater –something that outdated sewer systems can’t do.
Depending on the development, filtration systems can vary considerably.
At the southern branch of the Department of Labor and Health and Human Resources building near the Portland International Jetport, stormwater is retained and filtered in a large subsurface detention area under the parking lot, Puleo said.
Conversely, behind Dick’s Sporting Goods off Gorham Road near the Maine Mall, a retention area in the parking lot is partially above ground and divided into filtration compartments.
With these stringent stormwater standards that require strict management of stormwater, redevelopment possibilities, like NGL Supply Terminal Co.’s proposal to construct a liquid petroleum gas distribution facility at Rigby Rail Yard, can actually help the city accomplish that goal, Puleo said.
Rigby yard is “an area that has had a pretty dirty history over the years,” Dillon said.
The new stormwater treatment system that will be constructed if NGL’s site plan is approved by the Planning Board, Dillon said, is “definitely advantageous” in terms of improving runoff into nearby Calvary Pond.
On a smaller scale, the city’s standards have outlined ways in which residents can voluntarily treat stormwater on their property by installing rain barrels to hold rain water and building rain gardens to slow and retain runoff.
“Every Band-Aid we can put over one of those cuts that bleeds polluted stormwater into one of our streams is a good thing,” Dillon said.
In the near future, Dillon and Puleo said they hope to make a geographic information system map available to the public that charts all stormwater infrastructure installed since 2009.
It’s a constantly evolving process, Dillon said. The objective is not only to keep Casco Bay clean, but to eventually reverse the adverse impact on the city’s impaired streams, which he said “is a tall order.”
Of the city’s five impaired streams – Barberry Creek, Kimball Brook, Trout Brook, Long Creek and Red Brook – remediating the damage done to Long Creek is most feasible, Dillon said.
Dillon referenced South Portland’s logo, which includes a symbol of flowing water.
“Our job is to keep that blue water symbol from turning brown,” he said. “If you believe that global warming and sea level rise is real, becoming resilient and becoming prepared for (weather changes) in the coming decades, we have to have our infrastructre ready.”
A partially above-ground filtration system in the Long Creek watershed sits behind Dick’s Sporting Goods off Gorham Road. Systems like this one slow down the filtration of stormwater in order to filter out more pollutants before the runoff enters city streams and is eventually dumped into Casco Bay.