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Stormwater Management Techniques
In This Section
Low Impact Development Strategies
Low Impact Development (LID) Strategies
The following are examples of current stormwater management techniques that involve LID strategies:
Bioretention Cells: Bioretention cells, also referred to as rain gardens, are small landscaped, graded areas that are constructed with a special soil mix that can absorb and filter runoff. Low maintenance, water-tolerant plants are often used in these bioretention cells. These landscaping elements aid in reducing stormwater runoff, replenishing the aquifer, and filtering non-point source pollution. At Federal Triangle, the Ariel Rios South courtyard bioretention cells are lined, while the Constitution Avenue cells are not. Bioretention cells can be designed using waterproof liners with underdrains that discharge to a drainage system. The liners help avoid potential soil contamination or foundations. For more on this topic, see the Office of Water's bioretention applications fact sheet (PDF) (3 pp, 135K, About PDF).
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| Cross-section | Constitution Avenue construction | Constitution Avenue completed |
Cisterns: Cisterns are storage tanks that can be designed to capture stormwater runoff. Stormwater diverted and collected in cisterns can be used to supplement or displace existing potable water uses, such as irrigation, toilets, or cooling towers.
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| Cross-section | Cistern tank installation | Recycled glass art panel installation in cistern |
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| Close up of cistern beneath recyclable dome | Completed cistern | Completed cistern at night |
High Density Plastic Grid: This is a flat grid made of high density plastic that is a means to reduce soil compaction and maintain infiltration in lawns subject to vehicle traffic. This allows traffic to cross the area and still allow water to infiltrate into the grass.
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| Sketch of high density plastic grid. | Grid installed beneath grass on Constitution Avenue |
High Efficiency Irrigation: Irrigation techniques, timers, and moisture sensors can be utilized to reduce excess watering and promote water conservation. Furthermore, stormwater runoff can be collected in cisterns, which in turn can be used in place of potable water in these more efficient irrigation systems.
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| Irrigation head | Irrigation cap denoting non-potable water source | Water management equipment |
Permeable Concrete: This is a specially mixed concrete product with most of the fine aggregates, or stones, removed from the concrete mixture. The removal of the fine aggregates creates pores that allow water to travel through the concrete to a stone reservoir underneath the pavement. This allows stormwater to be filtered, detained, or infiltrated into the ground.
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| Under-drain with liner | Course stone/base layer | Fine stone/finish layer |
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| Path Completed | ||
Permeable Pavers: Permeable pavers are used to intercept and transmit runoff to permeable soils or gravel layers where pollutants are filtered, runoff is slowed, and aquifers are replenished. A gravel storage reservoir used in conjunction with pavers can hold large amounts of water to help control the timing and volume of runoff. The pavers, made of concrete, brick, or recyclable plastic materials, can be incorporated into grass and open areas or installed as roadways or parking surfaces. For more information see the Field Evaluation of Permeable Pavements for Stormwater Management (PDF) (2 pp, 66K, About PDF).
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| Cross-section | Stone filled between openings | Paver patio completed |
Runnels: Runnels are small surface depressions in sidewalk areas that safely channel small amounts of stormwater runoff. At Ariel Rios South Courtyard, stormwater is channeled from the runnels to the cistern for reuse in the irrigation system.
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| Sketch of a runnel. | |
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| Sloped runnel to drain | Cobbles sloped to form runnel |
Soil Amendments: Compacted soil does not absorb water well and therefore increases runoff. To correct this problem, soils may be improved through tilling, and/or the addition of organic material, fungi, worms, and topsoil. These processes restore the soil's water absorption and filtering capacity. Other benefits include reduced lawn maintenance, lowered irrigation, and healthier plants.
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| Trenching soil | Trenches with amendments being added |
Sustainable Landscaping: Sustainable plant species thrive with minimal maintenance. Most are native plants, which are well adapted to local conditions and best suited to respond to and/or reduce stormwater runoff. View the sustainable landscaping planting plan or the Ariel Rios South Courtyard plant list. For more on this topic, visit EPA's WaterSense Program, Greenacres, or Mid-Atlantic Region Green Landscaping Web sites.
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| Planting plan | Plant installation | Completed landscape |
Other Sustainable Techniques
The following are examples of current stormwater management techniques that do not involve LID strategies:
High Efficiency Lighting: Energy-efficient light fixtures are installed to light the walkway and cistern. Lighting contains low voltage and fiber optic lamps with daylight sensors and timers.
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| Fiber optic lighting inside cistern | Low voltage path lighting |
Recycled Content Materials: The site furniture is made from recycled metals and plastics. Recycled concrete and aggregates are also used in the construction of pavement bases.
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Plant sign made from farm tools
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Recycled content patio furniture | Recycled plastic used for walls of control bunker |
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| Recycled glass cistern cover | Historic granite curb removal | New location and use for historic granite curb as bench |
Water-Efficient Historic Fountain: Additional features added to historic fountain at the Ariel Rios South Courtyard include a recirculating pump that reuses water and eliminates the need for continuous potable water use.
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| Renovated fountain |