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

Los Angeles River East

The Pennypack Trust 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 William Penn Foundation who 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.  The entire basin-wide project is called the Delaware River Watershed Initiative.

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 in Haverford, Delaware County 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 subdivision in Whitpain Township, Montgomery County.  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 Lora Toran explaining testing equipment to monitor project effectiveness

After lunch, we toured a municipal sports complex in Horsham, Montgomery County where stormwater sheets off playing fields.  (Turf sheds water almost as effectively as asphalt.)  At this location, the municipality intends to create deep, rock-filled swales planted with native grasses or plastic igloo-like underground voids that will allow rainwater running off the fields an opportunity to soak into the ground rather than run off 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 in Abington, Montgomery County, the headwaters of Sandy Run drain 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, Sandy Run 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, Abington 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 Hurricane Floyd, 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.

 

Stormwater management is a difficult problem to address.  It took us literally centuries to for our urbanized watersheds to become like are in today.  Let's hope it doesn't take as long to correct the mistakes of the past. 

Headwaters Protection

Playground to be replaced with a rain garden

The Pennypack Trust is one of 80 watershed-protection organizations in the Delaware River basin that are participating in an ambitious collaborative effort called the Delaware River Watershed initiative funded by the William Penn Foundation to preserve and restore water quality in the Delaware River.

While the Pennypack Trust has not yet undertaken any projects in the Pennypack watershed, our sister organization, the Tookany-Tacony-Frankford Watershed Partnership (TTF) is going gangbusters on a small, heavily urbanized stream located just over the divide from the Pennypack watershed.

The stream, Jenkintown Creek, rises in a play area on the grounds of Abington Friends School.  The school is very interested in improving water quality in this small headwaters stream - both to be a good citizen, and also to use the restoration work as an educational resource for its students. On July 23, several of the local watershed organizations partnering in this collaborative effort took a tour of the work that has been completed on the school's property.

In the image at the beginning of this post, my friend and colleague Julie Slavet, director of the TTF, explained that the school is going to replace the existing grassy playground - the very beginning of the stream - with a rain garden that will capture runoff and allow it to percolate into the soil.

Newly planted riparian buffer.  The stream is flowing down the center between deer exclosures.

Just below the existing playground, the school has created 50-foot-wide riparian buffer plantings to shade and filter the nascent stream.

De-vine buffer

A bit downstream of the newly planted riparian buffer, the stream flows through existing streamside woodlands.  However, like all woodlands in the urbanized northern Piedmont (including the Pennypack Preserve), these trees were cloaked with invasive non-native vines.  The school's contractor removed the vines and planted individual trees in the areas freed of invasives.

Existing riparian buffer cleared of vines and expanded with new plantings

At the edge of playing fields

The soccer fields to the right of the image above shed precipitation almost as effectively as asphalt.  The school plans to create an infiltration trench at the base of the hill where the visitors are standing to capture the water coming off the fields and allow it to percolate into the ground rather than run directly into the stream to the left.

Parking lot runoff

The last stormwater management structure at the school will be a rain garden built at the end of the parking lot shown in the image above.  Now, when it rains, all of the water from the parking lot pours into the stream through the rocky gully visible in the image.  The school plans to capture the water in another rain garden and allow it to filter into the soil slowly.

Obviously, to make a difference in the overall Delaware River watershed, these types of projects will have to be repeated thousands of times over on countless small tributary streams.  But this is a great first step, and it serves as a model for others to emulate.