The entire design of Villebois is guided by three tenets: to preserve and promote connectivity, sustainability and diversity
And the community’s federally funded Rainwater Management Plan (RMP) achieves all three. It effectively connects residents to the area’s natural features through a diverse range of innovative means. Most importantly, the RMP manages rainwater in environmentally sustainable ways, helping to restore the land to its natural conditions prior to the development of the community. That’s good news for Villebois’ residents — and great news for the environment.
To design and build a community of approximately 2,500 homes, while maintaining local and regional watersheds in the “natural condition” which existed before development of the Villebois community.
Defining the Goal
The Villebois Rainwater Management Program (RMP) was developed to manage average rainfall so that both the volume and quality of water leaving the development is preserved as it was in pre-construction conditions. That is, the amount of water and pollutants carried to rivers and streams from the developed Villebois will remain unaltered from its pre-development state.
What is the Natural Condition?
In a natural setting, rainwater soaks into the soil and is then carried via natural processes to local rivers and streams. While acting as a vessel to transport the rainwater, the soil and plants also rid the water of pollutants.
How does the RMP differ from the conventional storm water system?
Normally, rainwater that lands on roofs, sidewalks, and streets runs immediately into a system of pipes, which quickly carry the water into local rivers and streams. Thus, rainwater reaches these bodies of water at a higher rate and larger volume than before development. Water that would normally take days to reach rivers and streams is now carried through pipes at a vastly quicker rate. This alters the amount of water in the system causing, among other things, erosion and pollution of local bodies of water. Large amounts of water are rushed through a single outfall pipe, which washes away plants and soil causing large-scale degradation of gravel beds and overall habitat reduction.
In addition to quantity, water quality is also adversely affected. Rainwater collects pollutants from streets and sidewalks, and carries this pollution to the watershed. There, pollutants reach wildlife through consumption of plants with harmful residue or from the contaminated water itself. A buildup of these toxins carried in fish and other animals can cause genetic mutations or even death. Overall, this conventional system is detrimental to the environment and Costa Pacific Communities has designed an alternative system that will help to prevent environmental damage.
The Villebois RMP utilizes sustainable techniques such as porous pavement and pavers, bio-swales, and bioretention cells to capture rainwater. Once collected, the rainwater is filtered through enriched soils and cleansed through natural processes. The rainwater has now been cleaned and slowed so it may reach the watershed at its natural rate via its natural soil system. In effect, the quality and quantity of water leaving the new community has left in the same manner as it did before development interference.
Rainwater Methods
Research shows that 90% of the rainfall events in Wilsonville consist of a half-inch of rain in a 24-hour period of time. The Villebois RMP would manage the half-inch of rainfall through several natural, on-site processes. Utilizing a variety of innovative approaches to rainwater management will enhance the aesthetic value of the community while contributing to the national database for Best Management Practices. The variety of approaches includeing mitigation ponds, porous pavers and pavement, bioretention cells, and experimental parcels of green roofing will show the capability and need for other developers to begin using this system.
Because scientific data concerning these new techniques is limited, the program at Villebois has made it a priority to test different methods. The results from the research we are doing will be public information to be added to the Environmental Protection Agency’s (EPA) database for Best Management Practices. The specific techniques that will be tested include six bio-retention cells, two green roof parcels, and porous pavement. The six bio-retention cells will contain different types of soil and plants. This will help determine which combinations are better for managing rainwater in the Pacific Northwest. The two green roof panels will be constructed with different drainage layers to test the benefits/limitations of each. Porous pavement will be tested for durability and feasibility. In addition to testing these different components within the Village Center, the overall Villebois rainwater management system will be monitored. Downstream monitoring systems will be put into place to ensure that the quantity and quality of water entering the watershed is the same as it was before development began.
Mitigation ponds
A large portion of the rainwater from the Village Center will be managed through a series of ponds along the 20-acre Villebois Greenway. These year-round ponds are engineered to hold and release rainwater at a natural rate to improve water quality. The system is able to hold and filter rainwater from the Village Center and neighborhoods within Villebois.
How it works
Rainwater from surfaces such as streets, roofs, and sidewalks is first directed into a bio-swale designed to receive and disperse rainwater. This is where soil and plants cleanse the rainwater. As more rainwater is directed toward the swale, it overflows into the neighboring pond system. It is then directed into an area called an infiltration bed where it seeps into the soil at its natural rate and quality. Overflow from the pond system is collected in a pipe, which is connected to the underground storm water system.
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The next largest portion of rainwater will be managed through sets of porous pavers.Pavers are considered alternatives to conventional pavement. They work just as well as pavement for human and automotive use but are able to filter large portions of water through unique openings where water is allowed to penetrate soil. Porous pavers are environmentally superior to pavement by allowing water to enter the soil naturally. They also reflect sunlight, allowing the surface to stay cooler during the summer months. Aesthetically, pavers add an attractive look that cannot be achieved through conventional pavement.
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Bio-retention cells (example – planter boxes)
This method detains runoff in the soil, allowing plants to remove pollutants from contaminated rainwater. This is similar to other methods that use plants and soil as a way to treat water runoff from pavement and roofs.
Porous pavement
Concrete and asphalt that contain “pores” allow rainwater to pass through small openings in the surface. This allows runoff to soak into a rainwater treatment area below the surface where it is treated for water quality and quantity.
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Experimental parcels of green roof
Green roofs (also known as eco-roofs) help lower the amount of runoff from rooftops. Standard roofing materials such as tar and shingles are replaced with soil and plants. Instead of rainwater rushing off of roofs, green roofs allow water to soak into the soil atop the roof as it would in a natural setting. Plants and soil are key components of this method as they help hold and clean the rainwater. Green roofs also allow buildings to remain cooler in the summer months and warmer in the winter by using soil and plants as insulation.
Funding
Funding for the Villebois RMP is supported by two congressional appropriations, which are administered by the EPA. Collectively, the grant money and private resources make this project valued at more than $1.1 million. Portions of this project include designing and implementing innovative rainwater management techniques, testing and monitoring these techniques, and education. Overall, the federal money that has been granted allows Villebois to go beyond a conventional system to an innovative approach that is both sustainable and aesthetically beneficial to the surrounding community.
Beyond Rainwater
In addition to rainwater, other sustainable endeavors may be incorporated to enhance Villebois’ environmental stewardship. Some of the enhancements under consideration include:
• Rehabilitating wetlands near Coffee Lake Creek and Arrowhead Creek-currently being studied by the Army Corp of Engineers
• Utilizing goats to clear blackberry bushes in a more sustainable, non-wasteful manner
• Placing debris from tree pruning into wetlands and parks
• Providing pedestrian and bicycle friendly roads throughout Villebois to promote alternative forms of transportation
Please visit our website at www.CostaPacific.com for additional information.
the design to capture rainwater. Once captured, the rainwater is filtered through enriched soils and cleansed through natural processes. The rainwater has now not only been cleaned, but is allowed to reach the watershed at its natural rate via its natural soil system. In effect, the quality and quantity of water leaving the new community has left in the same manner as it did before human interference.
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