January-February 2010

The Navy and Stormwater

As the government adopts new LID practices, one branch of the service charges ahead.

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Photo: Naval Base Kitsap

By Margaret Buranen

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In the parking area at the Washington Navy Yard’s Willard Park are several bioretention and detention cells, added when parking structures were replaced or repaired. One long strip bioretention cell and a smaller cell, approximately 10 feet by 20 feet, collect sheet flow from surrounding parking lots. The smaller cell also serves the bus parking area, the site of many oil leaks. A rain barrel collects and stores runoff from the roof of Building 292.

One very large UNI-stone permeable paver cell is in the center of the parking lot. A smaller permeable paver cell, adjacent to historical Building 70, collects runoff that flows through old copper downspouts, which are found on many of the oldest buildings within the Washington Navy Yard.

The historic Navy Museum (Building 76) has a rain garden that captures runoff from the roof’s copper downspout. The planting was completed through a partnership with DC Greenworks, a nonprofit organization. The project was part of the organization’s “Bridges to Friendship” program, which trains disadvantaged local youths in a trade.

The parking lot of Building 166, the Washington Navy Yard’s Dental Clinic, was regraded and repaved to ensure runoff flow to the LID features. It now has two large UNI-Stone permeable paver strips, each underlain with gravel chips and then several feet of gravel. The parking lot has curbs and curb cuts to allow runoff to flow into two bioretention cells.

Howard University students sampled runoff flowing into the western bioretention cell and also flow that was being discharged from the perforated pipes. Their study showed a 98 to 99% removal of sediments, metals, and other contaminants.

As for which of the LID projects at the Washington Navy Yard has proven to be the most impressive, Grigg says, “I have given many tours of the LIDs at the Yard, and I think maybe it’s the Building 166 parking lot. It shows that it can be done successfully, and that these LIDs still are very effective despite not having much maintenance.”

Storm drain inlets now keep trash and debris from entering the nearby Anacostia River. Careful planning means that installation of these LID features has caused minimal interference to visitors and employees. Best of all, no parking spaces had to be forfeited.

Additional stormwater and LID features have been added at various sites. These additions include a permeable paver patio to replace an impermeable one, disconnected downspouts to allow roof runoff to infiltrate, and storm drain inlet structures to trap sediment and debris. A tree box filter at the 9th Street gate lessens runoff around the site and cleans the water before it enters a catch basin. Aggregate gravel now allows infiltration in some open space areas.

Beyond the Washington Navy Yard, but still within the NDW, stands the US Naval Academy in nearby Annapolis, MD. The service academy has two bioretention cells and a permeable paver strip, visible to both midshipmen and visitors in the front of Alumni Hall and across the street in its parking lot. The cells replaced an existing under-designed and damaged trench drain and capture runoff from an area of approximately 1 acre.

In June 2007, six LID BMPs were completed at a naval facility in Solomons Island, MD They include one bioretention cell and five infiltration trenches. Grigg says the bioretention cell has “an underdrain and intercepts 0.52 acre of stormwater runoff from a parking area. The five infiltration trenches were installed to function as water-quality filtration and to alleviate flooding in three acres of campgrounds.”

Of these last two LID projects, Grigg says, “Both the Solomons and the US Naval Academy bioretention cells have been very successful in sparking the interest of Navy employees and the public. Our construction contractors were contacted frequently by passers-by and employees interested in the purpose of the LIDs and excited that the Navy was acting as an environmental steward.”

NSF Carderock has two planned LID projects that will be constructed in 2009. An existing parking lot of 1 acre will receive a bioretention cell with underdrain system. A new parking lot will be built according to the Navy’s LID policy, with a large bioretention cell to capture a portion of the new impervious area’s runoff.

The Navy’s new LID policy on stormwater will have influence beyond the confines of its property. Most of the LID features described above are part of installations that have National Pollutant Discharge Elimination System permits. Training for all Navy employees on LID techniques for managing stormwater begins in 2009.

B.J. Penn, assistant secretary of the navy for installations and environment, says that the Navy’s new LID policy “represents a commitment to preserving and protecting the environment where we work and live. The policy advocates a cost-effective solution that will help minimize the environmental footprint of our installations and facilities.”                                             

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