Yesterday, I wrote about the numerous storm drains that currently dump polluted water directly into Washington Channel. The District of Columbia recently adopted some of the nation’s most stringent and innovative rainwater policies, and the Washington Channel watershed stands to significantly benefit as plans and projects adapt to these new policies and incorporate state-of-the-art practices in green infrastructure (GI). The Natural Resources Defense Council’s “Rooftops to Rivers” report give DC’s new policies a high rank (just behind Philadelphia) among their “Emerald City Criteria” for river-friendly municipal policies.
The new Washington Canal Park, just a few blocks east of the Washington Channel watershed, recycles stormwater not just for its site but also for three neighboring developments.
The impetus for these changes came from the 2011 renewal of DC’s “MS4 permit,” the EPA permit for the storm drains that drain the urbanized part of the Washington Channel watershed (and 2/3 of the District), and is managed by the District Department of Environment (DDOE). As part of this process, DC has adopted a completely new set of stormwater regulations with three key innovations:
- a DDOE impervious surface charge to generate revenue for municipal green infrastructure, encourage existing buildings to reduce impervious cover, and reward “RiverSmart” properties (this is separate from DC Water’s impervious surface charge)
- a retention standard that requires new buildings to retain 1.2″ of rainfall on site (~90% of all rain events), and renovations to retain 0.8″ on site
- a credit trading scheme, the first in the country, giving the retention standard flexibility for dense downtown developments, rewarding efforts that go beyond, and generating funds for inexpensive GI improvements in the neighborhoods
Although DDOE expects only 1% of the city to annually be affected by the retention mandate, that’s still 10X the area currently affected each year by voluntary green infrastructure efforts.
While this change in stormwater regulations is currently only tied to the separated storm drain permit managed by DDOE, DC Water hopes that these efforts will be able to have an appreciable impact on its troublesome combined sewer system. If so, DC Water may be able to renegotiate an existing EPA mandate requiring billions of dollars in new “deep tunnel” pipes (see pg. 7 of this Brookings report).
These just-implemented policy changes are already shaping up to have a positive impact on the Washington Channel watershed, where much of the urban fabric will change in coming years.
- The Southwest EcoDistrict, a plan currently under development (primarily by the federal National Capital Planning Commission, with ZGF Architects) for the redevelopment of several blocks of mostly federal offices centered around 10th & D Streets SW, plans a truly cutting-edge water management scheme. The overarching goal is to reduce water use by 70% even while increasing the number of people on the site. Pages 11-29 of the May 2013 PowerPoint featured on their website goes into great detail about the strategies that the EcoDistrict can employ towards that goal: treating both greywater and air conditioning condensate water for potable use, storing a 1.7″ rain event in a truly vast cistern hidden underneath an existing bridge, and (by going beyond the 1.2″ mandate) receiving stormwater credits from other developments.
- Over half of the Washington Channel’s urban frontage (over six blocks) is included within plans for the Wharf, a proposal to completely transform the Channel’s shoreline. The development embraces the Channel with a new riverwalk and several public piers that will bring the public down to the Channel’s water — very different than today’s gated-marina frontage. Complying with DC’s 1.2″ retention standard earns the Wharf the maximum number of LEED-ND points possible under the stormwater management credit, helping it achieve its LEED-ND Gold rating. Among the innovative strategies planned: using stormwater as process water within an on-site combined heat & power (cogeneration) facility that improves both energy efficiency and reliability.
- Recent construction underneath the National Mall, part of which is within the Tidal Basin watershed, not only rebuilt the severely compacted turf but also included 500,000 gallons of rainwater storage in two cisterns — probably the city’s largest such installation. The Park Service plans another two cisterns as part of further Mall turf renovation, to store water running off the Mall (no, compacted turf doesn’t really do a great job of absorbing rain) and its drives for future irrigation uses. These cisterns could be just the start: in 2011, NCPC studied a two-block-long cistern, the entire width of the Mall, to store 20,000,000 gallons — enough to handle a 100-year rain event, and hopefully prevent the Federal Triangle from flooding again.
- Stormwater fees are also having an impact on a smaller scale. My own apartment building near the Washington Channel, built during the concrete-happy 1960s, has just embarked upon an aggressive program to replace paved surfaces — open roof, impermeable walkways and driveways — with green or permeable surfaces. This long-overdue plan was put into motion due to the new impervious surface charge.
In the future, big storms like tonight’s (but not quite so big) might actually improve the Washington Channel’s water quality, instead of harm it. Later: a look at the Washington Channel’s water chemistry, plus what that means for future evaluation of the channel. But tomorrow, I’ll look at how the physical form of the Channel shapes habitats along, and within it.
This semester, I’m taking a Natural Resources class through Virginia Tech about understanding local watersheds, wherein I’ll be researching and posting knowledge about the Washington Channel. You can explore the other watersheds that my classmates are investigating over at the class blog’s page. Other posts in this series can be found using the tag watershed.