Stormwater

pathway of north court residence hall at the university of richmond

Taking the Lead in Green Building

This Friday marks World Environment Day, organized by the United Nations. It has been recognized since 1974 with a different theme each year. In 2020, the focus is on biodiversity. As the U.N. notes, “World Environment Day offers a global platform for inspiring positive change.” That message aligns perfectly with our firm’s commitment to leave a lasting, positive impact in the communities we serve. Ultimately, that collective impact can benefit the world at large....

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Dam Safety in North Carolina

North Carolina is home to more than 5,700 dams, many of which are aging and unable to contain excess stormwater runoff from increased development and more frequent severe storms. As part of North Carolina’s recovery and resiliency efforts following recent hurricanes, which includes the governor’s flood control initiative, Draper Aden Associates evaluated more than 50 high-hazard dams in the Neuse and Lumber River Basins. These evaluations will help emergency management officials prioritize responses both before and after extreme storms by providing a clearer picture of the dam’s hydraulic capacity. Specifically, we were tasked with developing hydrologic and hydraulic computer model applications for each dam....

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edge of green roof on VMI's campus

A River Runs Through It: Stormwater Design at VMI, Part 2

The project site for the Corps Physical Training Facility at VMI presented the design team with a unique stormwater design challenge, which allowed for several creative solutions to minimize the stormwater impact of construction. The development of the site converted an area that had previously been mostly open space into a highly developed site, which without proper stormwater controls would cause a substantial increase in runoff as well as water-borne pollutants. To mitigate this, the project included installation of many stormwater practices including: bioretention, a green roof, permeable pavement, underground detention, a rainwater harvesting system, and several manufactured BMPs....

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flooding of town branch creek

A River Runs Through It: Stormwater Design at VMI, Part 1

The new Corps Physical Training Facility at VMI in Lexington, Virginia was completed in 2016 and houses two indoor tracks as well as other training features such as a high ropes course, climbing wall, and cardio equipment. The project’s location along Main Street in Lexington provided several unique challenges, including the existing Town Branch creek that runs beneath the new building. Because of past floods along this section of the creek, the design team developed a flood model to both guide the elevations of the proposed building and ensure that the proposed construction would not make flooding worse. [caption id="attachment_6495" align="aligncenter" width="770"] Flooding of Town Branch along Diamond Street in 2012[/caption] To account for potential flooding, the entire building is elevated above the creek level so that a 100-year storm can pass below without causing flood damage. The first level of the new facility is dedicated to parking, so that if a...

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What I’ve Learned About Bioretention: Part 2

Read Part 1 of this post here. 2. Bigger is not better Like most everything we design, when big things fail, they fail in a big way. Bioretention works best in applications where the drainage area to an individual cell is less than about a quarter acre. Larger bioretention areas are more likely to fail due to erosion because of larger flows, creation of low spots due to variations in the surface, and clogging of the surface layer. This can be avoided by dividing the area into multiple cells with smaller drainage areas. [caption id="attachment_6401" align="aligncenter" width="770"] Larger basin divided into three cells[/caption]   The largest bioretention area I know of is an example of this. Designed by others, it collects runoff from several acres at a highway rest stop. The measures designed to evenly distribute incoming flow have been overwhelmed by large flow rates, the engineered soils mix layer does not drain quickly enough, and...

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What I’ve Learned About Bioretention: Part 1

Bioretention areas (also sometimes called rain gardens) are a very useful tool in the toolbox of stormwater treatment BMPs. They provide a high level of pollutant removal and runoff volume reduction, and, if properly designed, require little maintenance. Bioretention was developed to mimic the hydrology of a natural forest. It consists of a shallow (typically 4-8 inches) basin with 3 inches of mulch and a variety of selected plants on the surface that can accommodate periodic flooding and drought. Under the mulch is a layer of engineered soil mix (typically 12-36 inches). The basin collects surface runoff and filters out nitrogen and phosphorus (nutrients for plants, but pollutants in stormwater) as water passes through the engineered soil mix. Water is absorbed by surrounding soils or is collected by an underdrain. The plants convert the nitrogen and phosphorus collected in the engineered soil mix into woody plant matter and leaves. If designed and...

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Grasses for the Masses

Glenn Telfer, Technical Leader for Sustainable Design in our Richmond office, is making a lasting, postive impact by taking part in the Chesapeake Bay Foundation’s (CBF) Grasses for the Masses program. He is volunteering to grow aquatic grasses from seed and plant them in the Chesapeake Bay. Aquatic grasses are a vital part of the chain of life in the Bay. Also know as submerged aquatic vegetation (SAV), they provide essential habitat and shelter for the young of many species, including crabs and fish. Without the shelter provided by thick grass beds in shallow waters near the shoreline, the young are exposed to predators. Glenn volunteered to be part of this program because it links with his expertise in stormwater design. “On every project, I design stormwater systems to reduce nutrient pollution into the Chesapeake Bay. Re-establishing the aquatic grass beds also helps to achieve the goal of a cleaner Bay.” Aquatic vegetation...

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2017 VA Stormwater Legislation

Keep up with all of 2017's Legislation Concerning Stormwater Issues from the Virginia General Assembly. The following is a representative list of the major pieces of legislation dealing with environmental concerns that were considered in the Virginia General Assembly during the regular 2017 session. This publication reflects the status of these bills as of the end of the regular session. Read the Stormwater Legislation here.   *This post was updated on March 1, 2017...

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New Certification Program Allows Stormwater Professionals to Shine!

The Chesapeake Bay Landscape Professional (CBLP) certification program is a new voluntary, regional (DC Metro area) advanced credential system and network of sustainable landscape professionals. The program was developed by a consortium of organizations, including the Chesapeake Conservation Landscaping Council, the University of Maryland, Wetlands Watch, the Virginia Department of Game & Inland Fisheries, Sea Grant Maryland, and the Virginia Habitat Partners. The goals of this program are to engage the landscape design and installation community, and provide a core set of professional standards and expectations related to stormwater Best Management Practice (BMP) selection, sizing, planting, installation and maintenance.   On January 26th – 28th, the first ever CBLP Level 2 (advanced) training program was held in Arlington Virginia, with 22 participants broadening their understanding of native plants, tree protection, and soils evaluation. My role in this program was to review the features, sizing and design for multiple BMPs, and hopefully added...

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Big Changes Coming to Virginia Ms4 Compliance

A massive project by the Hampton Roads Sanitation District (HRSD) has the potential to be a game changer for Chesapeake Bay Total Maximum Daily Load (TMDL) compliance for MS4 permitees. When complete in 2030, HRSD’s project SWIFT (www.swiftva.com) will treat all the sewage from HRSD to drinking water standards and inject the treated water into groundwater aquifers. The main benefits to this project are that millions of pounds of nitrigen, phosphorus, and total suspended solids will no longer be discharged to the York and Lower James watersheds and injecting water into groundwater aquifers should result in a decrease or reversal of sinking land elevations. HRSD plans to fund the projected $5 billion cost by raising sewage rates. In exchange, HRSD will give credits to the cities and counties which make up their service area. If allowed by DEQ, these MS4 permittees will be able achieve Cheasepeake Bay TMDL compliance at no additional...

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