EPA has issued “The Municipal Separate Storm Sewer System Permit Improvement Guide” to assist National Pollutant Discharge Elimination System (NPDES) permit writers in strengthening municipal separate storm sewer system (MS4) permits.

This guidance includes permit conditions with supporting rationale to be used in fact sheets accompanying NPDES permits, as well as recommendations for permit writers on how to tailor permit language to permit type.  EPA stresses:

Permit provisions should be clear, specific, measurable, and enforceable, including specific deadlines for compliance, clear performance standards, and measurable goals or quantifiable targets for implementation.

Permits should contain a performance standard for post-construction that based on maintaining/restoring hydrology to protect water quality of receiving waters, or another mechanism just as effective.

Contact Rachel Herbert by email or call her at 202·564·2649.

admin NPDES / MS4, National clean water, hydrology, MS4, Nonpoint source pollution, NPDES, water quality

As we noted in this post, Green Infrastructure is coming of age, and Philadelphia is at the forefront of utilizing innovative “greening” techniques. Be on the lookout for much more about these exciting efforts here on StormwaterPA in the coming months, including a series of videos that look at specific projects and sites.

In the meantime, amongst the useful articles in the January/February issue of Stormwater is one of special interest to us: “Philadelphia: Going Green to Manage Stormwater” (Margaret Buranen).  This is a nice acknowledgement of the Philadelphia Water Department’s nationally prominent green infrastructure program to better manage stormwater and the extremely serious combined sewer Overflow (CSO) problem.

Philadelphia’s changes in stormwater strategy began a major shift in 1999, when the City’s Water Department formed an Office of Watersheds to integrate sustainable wet weather solutions.

Dr. Christopher Crockett, PE, Director of Planning and Research at the Office of Watersheds:

In 2006, another major step forward occurred when we updated our stormwater regulations to require the management of the first inch of stormwater runoff for all directly connected impervious areas for any new or redevelopment with 15,000 square feet or greater of earth disturbance in the city.

The new regulations mean that “stormwater management” is part of the zoning and building permit process at the earliest stages.  Developers have many incentives to include LID and other green techniques to manage stormwater in order to meet those (2006) regulations.

Two years ago, the City Water Department proposed making a major change in the way billing was performed at the Water Department, essentially moving in the direction of a stormwater utility where stormwater billings for all non-individual residences would be based on impervious cover (80 percent weighting) and total lot size (20 percent weighting), rather than simply using water metering as in the past (notoriously inaccurate - large water users can generate relatively modest stormwater and large stormwater generators can use sometimes virtually no water!).  The new program has done much to encourage developers to incorporate partial and full green LID elements in new project designs.  Water Department success has been significantly reinforced with partnerships, such as with the Pennsylvania Horticultural Society’s Philadelphia Green.

In 2005, Philadelphia Green and the PWD started work on a project to address stormwater problems at seven Philadelphia schools.  At S. Weir Mitchell Elementary School, children created a raised bed vegetable garden in a paved parking lot, which will not only absorb stormwater, but also reduce the heat island effect.  Vegetation, infiltration trenches, bioswales,and a rain garden replaced some of the school’s 3-acre impervious site.

Another joint stormwater project, in South Philly, will include the city’s first sidewalk infiltration planters, on South 13^th Street.  Modeled after street planters used in Portland, OR, they are designed to reduce overflows that led to basement flooding, a persistent problem in the area.  These planters, which measure 30 feet long by 7 feet wide and are 4 feet deep, will be filled with native plants suggested by members of the PHS.

Ms. Buranen’s Stormwater article includes a wealth of information on Philadelphia projects, and we urge you to take a look!  This is definitely a Pennsylvania stormwater success story! You can find the complete article here.

admin green infrastructure BMPs, buffers, clean water, green infrastructure, hydrology, infiltration, LID, rain garden, rainwater collection, stormwater best management practices, water quality

At the end of November we offered questions and concerns about Riparian and Wetland Buffers for Water-Quality Protection: A Review of Current Literature, an article that was published in the November issue of Stormwater Magazine.  This week we offer other views on Riparian Buffers.

From the Stroud Water Research Center…

Stroud reports that the single most important factor in determining the quality of a stream’s water is the amount of forested land in its watershed. In 2008, the Stroud Water Research Center published Protecting Headwaters: The Scientific Basis for Safeguarding Stream and River Ecosystems. Although the focus is on headwater streams, the piece discusses forest buffers and how they provide many in-stream benefits including pollutant control, maintaining temperature control, providing food resources and habitat for aquatic organisms, and assisting in bank stabilization.  Click here for an executive summary or here for the full narrative.

From the Pennsylvania Campaign for Clean Water…

Pennsylvania Campaign for Clean Water has published its own platform on Proposed Buffer Requirements for Pennsylvania.  Read a summary of select studies reporting percentage of pollutant reductions based on buffer size.  Recommended is a minimum 100-foot buffer on all streams with additional buffer width for Special Protection waters, steep slopes, and more recently, headwaters, and impaired waters.  For the full Riparian Buffer Platform, click here.

admin Stormwater BMPs buffers, Chesapeake Bay, clean water, flood control, forested buffers, green infrastructure, hydrology, stormwater best management practices, stormwater runoff, stream restoration, watershed protection

There is no doubt that the Manual needs to be edited and updated.  For example, new technical information relating to BMPs has emerged which can and should be integrated.  At the same time, the line between “technical” and “policy” is a slippery one.   Sub-groups have been formed assigned to control Guidelines (i.e., stormwater standards) as well as methodologies.  Though issues surrounding both of these vital topics are hugely technical, they ultimately also are very policy oriented.  One could even argue that design specifications relating to how to build infiltration BMPs are policy oriented as well.

Understanding this somewhat “murky” separation between technical and policy, state environmental groups such as the Pennsylvania Campaign for Clean Water have contacted PADEP and are requesting that  the Revision Committee be expanded (see their letter below) in order to guarantee that important issues of water quality, hydrology, habitat, landscape ecology, and other aspects of environmental planning be fully represented and balanced in this Manual revision process (similar to the Oversight Committee which oversaw development of the existing Manual).  We will try to keep you informed as this process unfolds…

September 14, 2009

John Hines
Deputy Secretary
PA DEP
Rachel Carson Office Building
Harrisburg PA 17105

Dear John:

We recently learned about a series of meetings being convened by Domenic Rocco of the Southeast Regional Office to consider possible changes to the Stormwater BMP Manual.  We are very concerned that the group invited to these meetings includes few if any environmental stakeholders, and is overly representative of the interests of the regulated community–developers and the engineers that work and advocate for them.

As you know, the development of the BMP Manual was a rigorous process that included an Oversight Committee with broad stakeholder involvement and several public hearings to solicit public input.  The product of that effort was a technically sound guidance manual for reducing the generation of and properly managing post-construction stormwater runoff in Pennsylvania.  While we agree that the Manual should not be a static document and should be revised over time to reflect advances in the state of the art, any changes should be made in a very transparent way, with full involvement by a broad range of stakeholders, including the environmental and conservation communities. We believe the current process falls far short of this standard.

We encourage the Department to clarify the purpose of the meetings convened by Mr. Rocco.  If this is indeed the start of a process to revise the Manual, particularly the control guidances, we strongly encourage the Department to broaden the participants in the group, in particular adding representatives of the environmental and conservation communities, along with other interested groups including Conservation Districts and municipal officials.  In addition, the Department should clarify its plans regarding public participation in the Manual review process and the goals for such a process.

We look forward to hearing from you regarding our concerns at your earliest convenience.

Sincerely,

Bob Wendelgass
PA Campaign for Clean Water
1315 Walnut Street, Suite 1650
Philadelphia PA 19107

admin BMP Manual Revision, From the Editors BMPs, hydrology, PA BMP Manual, PA DEP, planning, stormwater best management practices, stormwater legislation, stormwater policy, stormwater standards, water quality

From the Chesapeake Stormwater Network… As a follow up to our blog last week on infiltration in and around limestone, read the blog on The Chesapeake Stormwater Network website that discusses Stormwater Solutions for Karst Terrain. Some of the important considerations include:

• Increased risk of new sinkhole formation by stormwater runoff
• Failure of stormwater practices and infrastructure due to sinkholes
• Greatly increased post-development runoff rates when land is paved
• Underground karst features are hard to detect and vary greatly over just a few feet
• Strong and often mysterious runoff/groundwater interaction make it hard to understand flow paths and drainage patterns
• Watersheds have lower stream density, losing streams and karst swales
• Polluted runoff greatly increases risk of groundwater contamination
• Need for special groundwater injection permits
• Changes in recharge or runoff quality can harm endangered species

Click here for the entire article including links to a 30-page technical bulletin and a powerpoint primer on karst terrain and stormwater.

This Week’s Food for Thought

Forests/Woodlands - the Tree as the only Best Management Practice!

“Penn’s Woods” ought to take its forests seriously.  We’ve become increasingly aware that woodlands provide valuable eco-services - critical watershed functions in terms of stormwater quality and quantity, as well as a host of other valuable functions.  Undisturbed forested cover, even in areas of “heavy” clayey soils, is capable of infiltrating remarkably large volumes of precipitation, after interception by forest canopy.   Evapotranspiration is maximized as well.  With such reduction in runoff volumes, water quality benefits as well.  Even in the largest storm events, runoff  from woodlands is surprisingly well filtered.  Not only does saving trees at a development site not increase stormwater runoff volumes, but undisturbed wooded areas can receive runoff and function as perhaps the only truly “best management practice.”  Trees are money in the bank from a stormwater perspective.

The positive role of trees in stormwater needs to be elevated.  Highly regarded research institutions like Pennsylvania’s Stroud Water Research Center are demonstrating that extent of forest remaining intact is perhaps the single most important variable relating to water quality and hydrology (i.e., overall watershed health) and overall watershed health.  And the value of trees is not limited to “mature specimen hardwoods” as has sometimes been thought to be the case.  Woodland areas with relatively immature trees can rank high on the eco-services scale.

In sum, the stormwater principle in terms of woodlands looks something like this:  fit the development into the trees - and if the trees are gone, try to replant and re-forest as much as possible.

Some comments and questions for your reaction:

-Does cutting down trees to make room for detention basins make any sense?

Perhaps the ultimate site planning insult (and absurdity) is clearing trees in order to build detention basins.  Many folks don’t realize that stormwater ordinances need to relate closely to municipal woodlands protection ordinances which should require rigorous tree replacement when trees are cleared from development sites.

-As critical as trees are to riparian buffers, upland forests are critical to watershed water resources, quality and quantity, as well.

In PADCNR’s Growing Greener program, woodlands are assigned a “secondary” resource status, in contrast to the primary status of floodplains and wetlands - should woodlands be taken more seriously in terms of stormwater management?

-PADEPs BMP Manual recommends a crediting methodology for trees and other environmental features.

Is anyone using these credits?  If you’ve used credits, what changes would you make? Are the credits meaningful?

Looking Ahead

Volume-Based Hydrology (VBH) is the very latest innovative thinking for stormwater management and is vastly different from the peak flow approach.  Andrew J. Reese explains this sea change in thinking - read the full article in the September issue of stormh2o.com. And look for more on this From the Editors next week…

admin From the Editors buffers, detention basin, forests, hydrology, infiltration, karst, ordinances, stormwater best management practices, volume control