Rambling Across Virginia

by Laurel Woodworth

It's been four months now since I finished my five-week trek across Virginia, my home state. In that amount of time I still have not found a good way to summarize the events or the feelings that I experienced during my trip. I hope these photos will help to capture at least some of the scenes I discovered along my 400 mile route, from the Alleghany Plateau in the west, over the Blue Ridge, into the vast Piedmont, and finally across the coastal plain and the Chesapeake Bay.

What I can say, however, is that the adventure offered many lessons. My intent was to learn something about waterways I had not yet seen. On this account, I was not disappointed. It certainly raised my Virginia water IQ. But the trip also provided me with lessons in Virginia history, lessons on travelling by foot and canoe, lessons in geography and geology, and lessons in gratitude.

I had a chance to meet and listen to some incredibly knowledgeable scientists, educators, fishermen, conservationists, and river guides who know their waterways like the back of their hand. One thing I discovered is that without these individuals sharing with me the history and treasures and tribulations of their waterways, I would have only seen what was on the surface as I walked by. Thank goodness for these storytellers, of which you are likely one. Every stream, river, lake, and estuary needs a storyteller and caretaker who can tell us what lies below the surface, the good and the bad, so that they are not ignored as we pass by.

I am grateful for the gift of time and good health that made it possible to take this walk and paddle across Virginia. It felt great to dive into the Atlantic, but truthfully, I was not ready to stop. There is so much to see and learn. Right now I am learning locally, finding out more about Buck Mountain Creek. There is something to appreciate in nature everywhere. I'll soon be ready to put on that backpack and head out again!

For stories behind the photos, click on the photos above, or visit www.walkacrossvirginia.blogspot.com  

Have an idea for a Runoff Ramblings topic?  Email us at rambler@cwp.org.

A "Spongier" DC

By Greg Hoffmann

The District of Columbia is looking to get "spongier."

How? By implementing a new rule that will require nearly all development projects to retain, or soak up, the volume of stormwater from 1.2" of rainfall.

Why? Because when runoff is retained, so are the pollutants associated with it, and reducing stormwater volume will also reduce the erosion of District stream channels. According to the District, this rule will:

"Significantly reduce stormwater pollution flowing into the Anacostia and Potomac Rivers and Rock Creek, and other District waterbodies by making the District spongier and better mimicking how the vegetated natural environment captures and uses rainwater and allows it to soak into the soil."

The 1.2" retention rule was influenced by the Runoff Reduction Method, developed by the Center for Watershed Protection (CWP), the Chesapeake Stormwater Network and Virginia Department of Conservation and Recreation. The 1.2" rainfall was mandated by the District's MS4 Permit as the regulatory event which equates to the 90th percentile storm event, i.e., in any given year, approximately 90% of the rain events in the District will total 1.2" or less. Accordingly, if a site has the capacity to retain a 1.2" storm event, it will retain approximately 90% of the rainfall that occurs throughout the year. The assumption is that by retaining such a high percentage of stormwater volume, much of the pollutants associated with the stormwater will be retained as well. This philosophy has allowed the District to venture away from regulating specific pollutants, such as sediment, phosphorus, or nitrogen, and simplify the rules.

CWP has been working with the District to answer the question of how a site can achieve the 1.2" retention standard. Relying on data in the Runoff Reduction Method technical memorandum (Hirschman et al., 2008), specifications developed in other Chesapeake Bay jurisdictions, and the knowledge and experience of staff at the District Department of the Environment (DDOE), CWP led the update of the District's Stormwater Management Guidebook. With the new retention standard came a need for new BMPs to be added to the Guidebook. It is important to note that these BMPs are not solely reliant on infiltration, which can be difficult to accomplish in the highly impervious District (43% of District's land area is impervious). Canopy interception, evaporation, transpiration, harvesting, and extended filtration also contribute to stormwater retention. CWP added urban-focused state-of-the-science specifications for green roofs, permeable pavement, bioretention, rainwater harvesting, downspout disconnection, proprietary practices, and tree planting/preservation to provide a wide range of options for meeting the 1.2" retention standard. CWP also developed spreadsheet design tools such as the Stormwater Compliance Calculator and the Cistern Design spreadsheet to aid developers and reviewers in showing compliance with the retention rules. The Stormwater Compliance Calculator provides a space for all of the BMPs used on a site to be tallied in terms of their retention performance, while the Cistern Design spreadsheet focuses specifically on sizing requirements and the associated retention value for rainwater harvesting.

One of the unique features of the stormwater retention rules and guidebook is the Stormwater Retention Credit (SRC) program. This program, developed by DDOE, acknowledges the fact that retention can be especially difficult and expensive for certain urban developments, and it also recognizes the many opportunities for retention retrofits in the heavily paved District. Therefore, rather than meeting all of its retention requirements on site, a development would be allowed to meet up to half of its retention requirements through the purchase of SRCs. One SRC equates to one gallon of stormwater retained for one year. SRCs can be accumulated by virtually any property in the District by providing more retention volume than is required for a development project or by retrofitting an existing development with retention BMPs. The SRCs generated each year can then be banked for future use or sold to sites that have not achieved their full retention requirements.

Though water quality trading programs exist across the nation, it is believed the District will be the first jurisdiction to operate a market-based trading program in the context of its stormwater management regulations.  While the desirability or fairness of a trading program is certainly a debatable topic (see Runoff Ramblings: The Old Question of Farms versus Towns: Who Should Be Responsible For Reducing Pollutant Loads in our Watersheds?), and implementation of the SRC program will considerably increase the workload for DDOE, the hope is that by creating an SRC trading market, the cost of compliance with the retention requirements will be reduced, and there will be a strong economic incentive to retrofit existing developments in the District. Further, the trading program may actually lead to a greater overall volume of runoff being retained in the District. For example, if a development chooses to meet the minimum retention requirement on site with a BMP that retains 0.6", and purchase SRCs for the remaining retention requirement, that means another site in the District will also be constructing a BMP that provides the equivalent of 0.6" of retention. This means that a greater area will be "treated" by retention BMPs. Since smaller rain events happen more frequently than large ones, the 0.6" retention BMPs will fill up more frequently, and on an annual basis, more runoff will be retained. For more information on the SRC program, see Brian Van Wye's article Making Stormwater Retrofits Pay in WE&T magazine.

The updates to the stormwater rules and the associated Stormwater Management Guidebook represent big changes for the way development will happen in the District. In an effort to alleviate uncertainty about these changes and get everyone ready to take them on, CWP and DDOE are providing training sessions for the groups that will be most affected. Introductory training sessions have been held for many of the District agencies, such as the Department of Transportation and the Water and Sewer Authority, to show how they will be affected by the stormwater changes. More detailed training sessions have also been held for engineers, developers, site plan reviewers, and inspectors, who will be implementing BMPs in the Stormwater Management Guidebook, and need to be very familiar with the practice specifications. Sessions focused on SRC certification and trading have also been held.

The stormwater rule and guidebook were published in August 2012, and are available for public comment until November 8, 2012. The proposed rule, draft guidebook, training presentations, and related information can be found on the DDOE webpage. The rules and guidebook are scheduled to take effect in July 2013.

Works Cited

Hirschman, D., Collins, K., and T. Schueler. 2008. Technical Memorandum: The Runoff Reduction Method. Center for Watershed Protection and Chesapeake Stormwater Network. Ellicott City, MD. 
  

The Online Watershed Library is Open!

The Online Watershed Library (OWL) is a service provided by the Association of Watershed and Stormwater Professionals (AWSPs) that allows practitioners to readily access Center for Watershed Protection and other watershed and stormwater resources to support the development and improvement of local programs. OWL is a searchable, online database of research, stormwater and watershed manuals and plans, assessment tools, and regulatory information. A monthly special feature of "hot topics" highlights innovative and up-and coming information to keep practitioners apprised of the latest stormwater and watershed issues. Users may also submit materials for inclusion in the OWL. OWL was developed to be a time-saver for watershed and stormwater practitioners as it provide users access to a well-organized database of relevant and up-to-date information.