Monday, August 10, 2015

Suburban Stormwater Tour: The Good, the Bad and the Ugly

Los Angeles River East
My organization is partnered with four other watershed organizations in the Philadelphia suburbs in a consortium that is working to improve water quality and reduce stormwater quantity in the Delaware River.  Our consortium works in the Philadelphia suburbs, but the philanthropic foundation that spearheaded this work is funding seven similar consortia throughout the huge watershed.  Our consortium is tasked specifically with reducing stormwater, while the consortia working in less-developed parts of the basin are working to reduce agricultural impacts and to preserve open space. 

Our work has been going on for 1-1/2 years now, and the staff of the foundation requested a tour of sites where the foundation's support has been used to implement stormwater management projects in the field.  On Thursday, August 6, the watershed organizations' and foundation's staff members gathered for a day-long bus tour of four sites scattered throughout the Philadelphia suburbs.    

First stop was at a private residence where a rain garden had been installed.  This rain garden was one of about 20 rain gardens that are being installed in prominent locations where neighbors and passers-by can become familiar with using a rain gardens to capture and infiltrate stormwater running off impervious surfaces instead of allowing it to pour directly into storm drains.
Publicity in the front yard
The rain garden, planted in May
Homeowner (blue shorts) and project consultants (right)
Second stop was a detention basin created to manage the stormwater for a 40-unit McMansion subdivision in a wealthy neighborhood.  While the basin was larger than needed to manage the stormwater generated by the subdivision, the basin was poorly designed and actually did almost nothing to detain stormwater.  The municipality has committed to modifying the basin by reducing the diameter of the discharge pipe (thus trapping and holding the stormwater for longer periods of time), creating islands, peninsulas, and pools within the basin to create habitat, and planting native vegetation throughout.
On the berm above the basin (about 10 feet deep)
Temple University hydrologist explaining testing equipment to monitor project effectiveness
After lunch, we toured a municipal sports complex where stormwater sheets off playing fields and discharges directly to a small stream.  (Turf sheds water almost as effectively as asphalt.)  At this location, the municipality intends to create deep, rock-filled swales that will allow rainwater running off the fields an opportunity to soak into the ground rather than run off directly to the adjacent creek.
Water from the playing fields (right) and parking lot pours into this swale, then directly into a creek
Grass swale will be replaced with a rock-filled infiltration trench
Later in the afternoon, we stopped at one of the most challenging and intractable sites imaginable; we wanted to show the foundation staff members just what our organizations have to deal with in the developed suburbs.  Here, a small headwaters stream drains a fully-developed residential and retail neighborhood.  Because the watershed has so much impervious surface (e.g., driveways, rooftops, lawns, and roads), very little rain water soaks into the ground, so the stream has almost no baseflow during dry periods.  However, when it rains, the stream turns into a raging torrent because all of the imperious surfaces shed water directly to the creek.  Unfortunately, this neighborhood is densely developed, so the stream channel is located in residents' backyards and there's nothing that can be done to widen the channel or create stormwater detention.  Instead, the municipality confined the creek to a concrete channel reminiscent of the infamous Los Angeles River to sluice the water downstream as quickly and "safely" as possible. 
Concrete confines
During our last hurricane, two people living downstream of this channel drowned in their basement when the water rose up in a flash and flooded the house.  So much for safety.


packrat said...

Brilliant work being done there, Scott. I'd venture to say that not many pro-growth developers in olden days gave much thought to how impervious surfaces--so convenient for citizens in so many ways--would work against cities in their watershed planning.

Planners with acute foresight were often derided for wanting to get things right from the start. As an example--if you have time--read what's happening in my hometown of Youngstown, Ohio, and see how one such planner was treated.

robin andrea said...

Rain water and pavement, such an interesting dilemma. I like how you and the consortium are coming up with plans to deal with the problems. Water is such a crazy issue here in California. We're looking at the possibility of an El Nino, and it will likely produce flooding and landslides and not make up much for the drought. If the storms don't hit here up north, the water supply is not replenished.

Scott said...

Packrat: You're absolutely right. The development mantra was to get the water downstream as quickly as humanly possible. Now, decades later, the receiving streams are paying the price. Most municipalities around here now have stormwater management ordinances that require significant detention or infiltration when an area is newly built or is re-built, but existing development is exempted. So, it will take decades (centuries?) for everything to begin to return to better conditions as our dense urban communities gradually are rebuilt.

Thanks for the Youngstown link, too.

Scott said...

Robin Andrea: Sounds like feast or famine for California--and mostly famine right now. When it does rain, there's flooding and landsliding. The work we're doing is literally a drop in the bucket right now, but at least it's a start.

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Daniel Roberson said...

Admirable work there, the way I see it. Truly, the dangers of rogue stormwater cannot be taken lightly, and you guys are employing ingenious methods. Here's to hoping your work continues to benefit the residents. Cheers!

Daniel Roberson @ Mark Bentley PA

Scott said...

Daniel: The dangers of rogue stormwater cannot be taken lightly. There have been several drownings in the streams around Philadelphia after particularly large storm events. Kids who think they are invincible seem to be the routine victims, but we've had people drown in their homes and even had a gas furnace explode and kill people when the furnace floated away and the gas line was severed and caught fire.