Hidden dune filters treat coastal stormwater runoff
Researchers from North Carolina State University have developed low-cost stormwater filtration systems that are concealed beneath sand dunes and filter out most of the bacteria that can lead to beach closures. The researchers designed and built two such systems in Kure Beach, N.C., that consist of large, open-bottomed chambers that effectively divert the stormwater into dunes, which serve as giant sand filters. The systems are built under dunes that are covered with vegetation. The researchers then launched a three-year study to see how the filters would perform. The dune infiltration systems reduced the concentration of bacteria in stormwater runoff by 96 percent.
"It was not economically feasible to use a tract of beachfront property to treat stormwater. Instead, we were able to devise a system that could be installed in an area that was not developable – underneath the dunes," said Michael Burchell, Ph.D., an assistant professor of biological and agricultural engineering at NC State and senior author of a paper on the research. The filters "exceeded our expectations" at removing bacterial pollution, Burchell said. And the study found minimal impact on groundwater. There were short-term increases in groundwater levels during storms, but those increases dissipated in anywhere from a few hours to two weeks.
"And we found that after replanting, the coverage of the dune vegetation actually exceeded what had been there previously – which is important to dune stability," Burchell said.
Burchell's team has since installed a third dune infiltration system in a more developed location to see if the system is able to handle higher flow rates, water volume, and concentrations of bacteria. That work is ongoing, but early results are promising. The work was supported by the North Carolina Department of Transportation, and the filtration systems were installed by the Town of Kure Beach.
Information provided by North Carolina State University
Response to Chesapeake Bay TMDL requirements
Local jurisdictions and transportation agencies in the Chesapeake Bay watershed are responding to the requirements of the Chesapeake Bay Total Maximum Daily Load (TMDL) for nitrogen, phosphorus, and sediment across all source sectors including municipal and industrial wastewater treatment plants, septic systems, agriculture, and urban stormwater. Each state in the watershed has been assigned an allocation of nitrogen, phosphorus, and sediment that can be discharged to the Bay, and the states have distributed the allocation among the local jurisdictions requiring Watershed Implementation Plans (WIPs) that demonstrate how the required reductions will be achieved. The WIPs address reductions required to achieve aggressive two-year milestones and include all source sectors with the exception of agriculture (which is being addressed by Soil Conservation District workgroups), including how future development will be managed to maintain the required reductions.
A significant focus has been placed on reducing stormwater-borne non point source pollutants that wash from impervious surfaces, particularly from jurisdictions that have Municipal Separate Storm Sewer (MS4) permits. During the 2012 legislative session, the Maryland General Assembly required local jurisdictions with MS4 permits to develop a means of funding the stormwater retrofits and the ongoing operation and maintenance costs that will be required to comply over the long term. Montgomery County, Md., implemented a water quality protection charge several years ago to provide a long-term funding source for its stormwater program after its MS4 permit conditions required retrofit of impervious surfaces that lacked stormwater controls. Howard County, Md.'s County Council enacted its stormwater funding program in March 2013, and Anne Arundel County, Md.'s County Council is conducting public hearings on its program currently. In all, 11 local jurisdictions are required to implement programs to fund the required stormwater retrofits and maintenance programs.
In addition to enacting ordinances to fund stormwater retrofits and maintenance programs, local jurisdictions are conducting watershed assessments and are evaluating impervious areas that lack any form of stormwater management as well as impervious areas controlled with only quantity-based (flood control) stormwater management structures. Jurisdictions such as Howard County are looking first for the "low-hanging fruit" among existing facilities where dry ponds designed for flood control can be expanded and converted to extended detention facilities with sediment forebays and/or micro pools to improve water quality performance and capture the necessary nutrient reductions.
Transportation agencies in the Bay watershed, including the Maryland State Highway Administration (SHA) are also MS4 permit holders, and they too are evaluating impervious surfaces that lack stormwater management and are designing retrofit projects to respond to the Bay TMDL requirements. SHA has many stormwater retrofit and outfall stabilization projects either planned, designed, or in construction. One stormwater retrofit project designed by SHA included bioretention and bioswales for a portion of MD 32, a six-lane divided highway that in some locations has no stormwater management controls. The retrofits have been designed to provide water quality treatment in the roadway median to provide water quality management for roadway runoff prior to discharge into the existing closed storm drain system.
By Eileen Straughan, president and founder of Columbia, Md.-based Straughan Environmental (www.straughanenvironmental.com).
Coordination crucial for massive retaining wall
When plans were being made for a new Sam's Club in Hendersonville, Tenn., developers were presented with several challenges regarding a retaining wall on the property. First, the 32,323-square-foot wall would reinforce a large area, rising 30 feet high and running nearly a half mile long. Areas behind the wall had a steep 3:1 slope, access roads for deliveries had to be accommodated, and because it backed up to a popular walking/bike path and green area, it had to include safety railings. Plus, the upscale area warranted an attractive wall system and design. Additionally, the pressure was on to stick to a tight schedule because the building pad could not be started until the wall was at certain heights. Coordination was critical.
General contractor White Spunner, Mobile, Ala.; wall contractor Retaining Walls of Tennessee, Gallatin, Tenn.; Lee Brick and Block, a Keystone Retaining Wall Systems manufacturer; engineering design firm Terracon Consulting; and Strata System's engineers worked closely to plan the wall. The process involved blasting and removing 250,000 cubic yards of limestone and placing No. 57 crushed stone in its place for fill behind the wall. Strata worked closely with Terracon's engineering team to specify the appropriate geosynthetic reinforcement materials and amounts needed for the varying conditions of the site. A total of 38,000 square yards of Stratagrid SG200 and 10,800 square yards of Stratagrid SG500 were placed behind the wall to reinforce the soil and rock. The wall was faced with attractive Keystone Compac III Hewnstone to complement the upscale look of the development. At the top of the wall, fencing was reinforced with 282 Sleeve-It rail integration system units to stabilize the fence along the walking/bike path.
Sam's Club was provided with a stable, well-built wall that is an attractive feature to the shopping development and complements the upscale area and green area above it. Further, because the perimeter of the road behind the Sam's Club is adjacent to the wall, it allowed maximum use of the 19-acre site. Hikers and bikers along the path near the wall are kept safe with reinforced railings. The project was well-coordinated with the entire development team and kept to the timeline, enabling the pad to be installed on time.
Information provided by Strata Systems
Restoring clarity to Lake Tahoe
Lake Tahoe Basin was geologically formed about 2 million years ago. Over time, snowmelt from the surrounding mountain peaks filled the basin creating Lake Tahoe, one of the deepest freshwater lakes in the United States with a maximum depth of 1,645 feet and 72 miles of shoreline. With more than 3 million visitors each year, this breathtaking destination features the United States' largest alpine lake nestled against the backdrop of the majestic Sierra Nevada Mountains. This pristine environment offers many activities for outdoor enthusiasts ranging from hiking to water sports. It is this draw that has increased development along the north shore of Lake Tahoe.
Development and urbanization of the basin altered natural drainage paths and runoff patterns, and decreased the opportunity for precipitation to infiltrate into the ground. It also resulted in Stream Environment Zones being filled to accommodate development. This further decreased the opportunity to reduce sediment and nutrients through natural functions before runoff reaches the lake. The roads, structures, and related infrastructure such as parking lots associated with urban areas caused increased runoff volumes and rates that concentrate flows and erosive forces. These flows generate and carry with them fine sediment and nutrients, often directly into streams and the lake.
For years, sediment deposition into Lake Tahoe has affected its water quality. For example, there has been a recorded gradual reduction in Secchi depth, which is a measure of deep water transparency. Reduced Secchi depth led Lake Tahoe to be listed on the 303(d) list of impaired water bodies.
Due to the adverse effects stormwater runoff sediment deposition has on Lake Tahoe, The Placer County Public Works Department (along with other entities such as the California Tahoe Conservancy and Tahoe Regional Planning Agency) commissioned the West Sunnyside Erosion Control Project. The project was part of the Environmental Improvement Program in the Lake Tahoe basin. Its overall goal was to prevent source erosion and treat stormwater before being discharged into Lake Tahoe. Specifically, products were required to treat the entire flow of water and provide inflow and outflow pipes at the same elevation. The West Sunnyside Erosion Project presented a wide array of challenges, even further complicated by the project's unique and precarious location on a steep slope.
Bio Clean Environmental Services, Inc. met and exceeded the design constraints of the West Sunnyside Erosion Control Project by installing its Nutrient Separating Baffle Box (NSBB). The system is a self-contained treatment train that provides screening and multi-chamber hydrodynamic separation. The NSBB was a perfect choice for the project because inflow and outflow pipes could be placed at the same elevation.
To address the placement challenge, the NSBB was designed and installed to sit on the edge of a high hill overlooking Lake Tahoe (see page 48). "Considering the location, steep slope of the outflow pipe, and hydraulic conditions, we felt the NSBB was the perfect solution due to its high adaptability with respect to location placement and proven performance in sediment reduction." said Zach Kent of Bio Clean. After being filtered, the treated runoff enters the outflow pipe and immediately drops 60 degrees downhill and runs approximately two miles to a detention basin. The cost of the entire system was just under $29,000.
The NSBB went online in August 2010 and to date has been instrumental in capturing and holding large quantities of sediments that otherwise would contribute to the reduction in Secchi depth in Lake Tahoe. "We feel that the NSBB is groundbreaking technology that will dramatically improve water quality in Placer County, and the Lake Tahoe basin," said Placer County Engineer Greg Keaveney about six months after project completion.
Information provided by Bio Clean Environmental Services, Inc.
Solar-activated stormwater treatment technology wins funding
Oregon BEST awarded a commercialization grant to an industry-university team developing a floating, solar-activated stormwater treatment device that could be deployed in retaining ponds or ditches along roadways and parking lots to keep contaminants from reaching streams. The technology could also be used to pre-treat stormwater, helping reduce overflow situations at municipal treatment facilities during severe weather events.
Beaverton, Ore., startup Puralytics is building on the success of its SolarBag portable drinking water purification system, which uses a nanotechnology-coated mesh activated by sunlight to purify 3-liter quantities of water in approximately three hours. The company is incorporating the same technology into thin, round pads that would float a few inches below the surface of standing stormwater and treat much larger volumes.
The Oregon BEST funding will enable Puryalytics to work with faculty and students affiliated with Oregon State University's (OSU) Institute for Water and Watersheds (IWW) to evaluate the overall concept of the new system, establish key design parameters, and generate third-party test data. The OSU research team, led by Todd Jarvis, Oregon BEST researcher and the interim director of the IWW, will construct artificial ponds or tanks that can be closely controlled and monitored, where prototypes of the water treatment devices will be tested.
"Although there's a lot of work going into bioswales and semi-permeable surfaces and self-cleaning coatings for buildings, these are large-scale, expensive engineering projects," said Mark Owen, CEO of Puralytics. "Because our solution is simple and small and has particular promise for cleaning up trace chemical contaminants, we're starting to see increased customer interest."
The Oregon Department of Transportation has expressed interest for two reasons, Owen said. First, the technology has the potential to keep highway surface contaminants such as petrochemicals, copper from automobile brakes, other metals, and biological waste from animals from entering nearby streams. And if water in retention ponds along highways could be purified to a high enough level, it could potentially help meet federal clean water availability requirements during emergency situations.
Municipalities are also interested in the technology because it could lead to decentralized treatment of stormwater, potentially diverting millions of gallons from entering water treatment facilities. This could save cities money and reduce the incidence of combined sewer overflows when treatment facilities are overwhelmed during high water events.
Information provided by Oregon BEST
Sustainable site design awarded
R.A. Smith National received a 2013 State Finalist Award from the American Council of Engineering Companies (ACEC) Wisconsin for the Alterra Coffee Roasters in a Bay View neighborhood in Milwaukee. Sustainable site design and landscape architectural design services were provided to The Kubala Washatko Architects for the new 27,600-square-foot cafe and wholesale bakery.
The project started as a two-story Maritime Savings Bank building on a one-acre site and was transformed into an environmentally sustainable Alterra café and bakery. Alterra wanted to create a site that would reflect its commitment to minimizing environmental impacts. An integrated series of living displays at the Alterra site demonstrates an innovative use of stormwater. The combination, type, and number of these uses demonstrate the practical, cost-effective means of collecting, storing, and reusing stormwater in an aesthetically pleasing, user-friendly manner. The sustainable design techniques that were implemented include an aqueduct/waterfall feature, shade garden/rock garden, cistern, dry stream bed, and a vegetated roof.
Alterra co-founder Lincoln Fowler said "Our decision to redevelop an urban site at one of the busiest intersections in the City of Milwaukee presented several design and construction challenges. Our commitment to sustainability, shared by R.A. Smith National, led our team to turn these challenges into an opportunity to promote the benefits of sustainable development to the community."
Information provided by R.A. Smith National
Park proposed on top of freeway
The Friends of Hollywood Central Park (FHCP), a non-profit organization dedicated to building the Hollywood Central Park (HCP; http://hollywoodcentralpark.org), selected FirstCarbon Solutions to prepare the Environmental Impact Report (EIR) and other necessary studies for the HCP project. Supporting one of the most dense and green space-starved neighborhoods in Los Angeles, HCP is a planned 44-acre street-level urban park built over a one-mile stretch of the Hollywood Freeway (US 101) as it travels below grade between Hollywood and Santa Monica Boulevards.
HCP began as an idea more than 28 years ago. In 2006, it progressed from a Hollywood Chamber of Commerce initiative to a Hollywood Community coalition and finally to FHCP. Funding for the EIR was made possible by a $1.2 million donation from the Aileen Getty Foundation. Additionally, the City of Los Angeles contributed $825,000.
In cooperation with Los Angeles Bureau of Engineering, the EIR lead agency, FirstCarbon Solutions will prepare the required California Environmental Quality Act documentation on behalf of FHCP. As part of the EIR and other necessary studies, the FirstCarbon Solutions team will provide community impact assessments, traffic/circulation studies, noise and vibration assessments, air quality studies, as well as conduct geotechnical and hazards/hazardous materials investigations.
Information provided by FirstCarbon Solutions
RBF Consulting to design California master planned community
RBF Consulting, a company of Michael Baker Corporation, was selected for a $1.7 million contract for the La Entrada Master Planned Community in the City of Coachella in Riverside County, Calif. The project site lies along the foothills of the grade to Chiriaco Summit, with views of the Coachella Valley.
The specific plan for the La Entrada Master Planned Community, owned by PSAV, LCC, and managed by New West Development, proposes 7,800 dwelling units, recreational park areas, and commercial development on 2,200 acres. RBF will provide entitlement services, planning, jurisdictional delineation, preliminary engineering, landscape architecture, and master planning of sewer, water, and storm drain systems. In addition, RBF will prepare project reports and environmental documentation for a proposed Interstate 10 interchange at Avenue 50.
The City of Coachella, incorporated in 1946, is currently updating its General Plan with smart growth and green principles, with a health and wellness component resulting from a grant from Building Healthy Communities.
Information provided by RBF Consulting
Submit news and photos of planned, ongoing, or recently completed projects and research to Bob Drake at email@example.com. In August, "Project Notes" will highlight erosion control and retaining walls; in September, transportation and mining/energy projects are the focus.