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.

A Ray of Hope

On Friday morning, February 13, I joined my landscape restoration students for tours of an urban oasis featuring the latest stormwater management and native gardening concepts.  My graduate students gathered for their tour at 8:30 a.m., and then my undergraduates met at 11:00 a.m. for a second tour.  When we got to the site, the temperature was 8 degrees F, and the wind was blowing strongly.  To say it was cold was an understatement, and the temperature had only risen to about 18 when the undergraduates convened for the second tour.

The site was the Salvation Army's Ray and Joan Kroc Community Center in Philadelphia.  Ray Kroc, founder of McDonald's restaurants, and his wife, Joan, gave the Salvation Army over $1 billion to build community centers in severely disadvantaged urban neighborhoods across the country.  I'm not much of a fan of the Salvation Army (because of their discriminatory practices) and everyone has an opinion about McDonald's.  Our tour leader, Chris, shared my opinions about both organizations, but he conceded that the community center was a godsend for the impoverished neighborhood in which it was located and he commended the Salvation Army for its good deeds here.

The site had been a lightly-contaminated brownfield associated with the Budd Manufacturing Company, one of Philadelphia's largest employers when manufacturing was king.  Budd's thousands of workers built zeppelin gondolas, railroad cars, and airplane parts.  Today, the factory buildings are vacant, derelict and marred by graffiti.  The 13-acre Kroc site had been a parking lot for Budd's workers.

When the Salvation Army decided to locate the community center on the site, they hired the local but widely-renowned landscape architecture firm Andropogon (named for a genus of native grasses) to design the landscape.  With Philadelphia's extremely strict  stormwater management regulations, the Salvation Army insisted that the designed landscape capture, retain, and infiltrate as much water as possible.  Andropogon's designers also decided to make the project "zero waste" - no material would be removed from the site.

All of the existing parking lot pavement was either recycled to be reused for porous pavement on the new parking lot or was spread to level the site.  Slightly contaminated soil was buried deep under the site and encased in compacted soil.

Bioswale

The new porous pavement parking lot was divided into sections separated by bioswales.  Any stormwater which does not drain through the porous pavement runs into the bioswales planted exclusively with native species.  Stormwater which fails to infiltrate in the bioswales is gathered into one location and diverted to an extended detention and infiltration basin called Rain Garden B.

Roof stormwater management system

The community center building covers two acres.  The architects determined that installing a green roof would have been prohibitively expensive.  So, instead, they worked with Andropogon on an alternative.  Rain falling on the roof collects in three locations and spills into downspouts integrated into the building's design.  The spouts discharge into decorative runnels, which direct the water into one of two cisterns buried in the center of the site.  The cisterns were designed to supply water to the property's landscape irrigation system but, unfortunately, the irrigation system failed soon after it was completed and now the cisterns simply discharge into Rain Garden A when they are full.

Cleverly disguised downspouts and decorative runnels

Tour leader Chris demonstrating the capacity of the runnels

Small rain events fill just the central sculpted channel in the runnels, while larger events fill the broader channel.

Sculpted runnel designed to look like flowing water

Students standing at he edge of Rain Garden A that receives the discharge from the roof cisterns

All three of the rain gardens on the site were dry when we visited..  If Rain Garden A fails to infiltrate all of the stormwater it receives from the roofs, the excess water can flow into Rain Garden B, which collects water from the parking lots.  And, if Rain Garden B cannot infiltrate all of the water, the excess flows to Rain Garden C, which also includes a structural outlet to the city's stormwater sewers - a "fail safe" in the event of a major flood.  Chris emphasized that Rain Garden C had never spilled any water into the city's sewers since it had been built (though he admitted that we hadn't had a hurricane yet, either).

Rain Garden B on right of path

Last stop.  Rain Garden C, which can handle the overflow from A and B, if necessary.

The plantings in Rain Garden C included some bald cypress trees in the bottom of the basin.  Bald cypresses will survive this far north, but they are not part of the native flora.  I didn't challenge Chris on the issue, so I can't explain the reasoning behind planting cypress (versus a more northern species that could also tolerate wet feet like swamp white oak, pin oak, or sycamore).  With global warming, the cypresses may be very happy in the near future, but there was no evidence of global warming on the morning we visited!

At the Headwaters

At the headwaters of my creek

My preserve is located in the center of the watershed drained by the creek flowing through the preserve.  Downstream of my preserve, the creek's floodplain and some of the adjacent steep slopes are pretty well protected in county and city parks.  But upstream of my preserve, the watershed has largely been built out in typical suburban style.

As a result, the biggest environmental problems with my creek are related to stormwater runoff from the impervious surfaces upstream of my preserve.  Stormwater generates problems like erosion, sedimentation, turbidity, flooding, and low stream baseflow between storms (because precipitation runs off impervious surfaces and does not have a chance to filter into the ground to recharge springs).

One of the largest Philadelphia-area philanthropic foundations recognizes these problems in my and my neighboring suburbanized watersheds, and the foundation has begun a multiyear, $37 million initiative to begin to address these problems.  On Tuesday, I learned that our organization had been awarded a $165,000 grant to create a stormwater detention wetland at the very headwaters of my creek.  The wetland basin will intercept the runoff from a 40-acre housing subdivision, infiltrate part of the water, and trap sediments, thereby improving water quality in the creek (we hope). 

Project manager (center) pointing out details of the project

Though my organization was awarded the grant, we will be building the wetland project on another non-profit's property: a summer camp for economically disadvantaged children.  The camp, which has a strong environmental education component, will use the wetland to teach children about the importance of stormwater management.  At 235 acres, the camp is the largest natural area upstream of my preserve, and it's located right at the headwaters of my creek.

A representative of the foundation (in pink, on right) explaining  the foundation's goals

On Wednesday, July 16, project engineers, university scientists, and a representative of the philanthropic foundation that is paying for the project visited the site - currently a wet swale in a meadow.  We'll be starting work on the project in the next few weeks.

I'm not overly excited by this project because (1) it's not in my preserve (where there's already plenty to do), (2) it's not going to make much of a difference in terms of water quality in a 56-square-mile watershed, and (3) there's almost no money in the tight budget for project administration.  However, it gives our organization good "press," receiving the grant makes me look good to my board of directors, and the project is a step in the right direction for the watershed, so I'll take it.

Departing the site.  There are worse places for a walk on a sunny summer afternoon.