Focus on
Stormwater Management

Watershed Stewardship
While most people think of watershed stewardship as a large scale planning process spanning across political borders, the principles of watershed stewardship have to be applied on every scale to be effective. Following are techniques we use for managing water resources on an individual site.


CLICK PHOTO TO ENLARGE [+]

Traditional Design Problems Sustainable Design Solutions
Water is piped off-site as quickly as possibly contributing to downstream stream bank erosion Water is kept on the site to be recycled (ex. water plants, flush toilets).
Most old sewage and stormwater systems are piped together (ex. Phila.). Sometimes, during large storms, the sewage and stormwater mix and discharged directly to local waterways without treatment. Water is recycled on-sited (ex. water plants, flush toilets).
Treatment plants do not create habitat. Fish, plant and bird habitat is created.
Treatment plants require the addition of chemicals and energy. Constructed wetlands operate using gravity, wind and sun.
Highly trained maintenance staff required. Maintenance is basic.

Back to top

Vegetated Swales
There are two common types of constructed swales used to treat stormwater, cleansing swales and bioretention swales. Cleansing swales slow the flow of water through the site through careful grading and vegetation. Swales meander down hills to provide a shallow slope for the water to move along. Along the way, plant roots take up water and the mass of the plants creates a barrier that physically slows the water. Check dams that create small pools can be incorporated into the design to provide a little extra on-site storage and further slow the water so that settling can occur. Bioretention swales are cleansing swales with additional infrastructure (sand, piping, and concrete) to provide storage and further infiltration opportunities.

Recharge Beds
Recharge beds are carefully built gravel filled basins designed to replace traditional surface detention basins. Great care must be taken during construction to ensure that the gravel is clean and that excess compaction doesn’t occur. Recharge beds are often installed beneath porous pavement, but can be installed beneath impervious pavement as well. Overflow can be piped into municipal systems, but preferably, it should infiltrate to the aquifer thus allowing it to re-enter the hydrological cycle.

Traditional Design Problems Sustainable Design Solutions
Valuable water resources are piped off the site as quickly as possible contributing to downstream flooding. Water flows through the site slowly with opportunities to re-enter the hydrologic cycle by evapo-transpiration or filtering into the aquifers below.
Water running off paved surfaces and through a sloped site can gather momentum and cause erosion problems. Traps sediment to diminish soil erosion.
Pipes don’t filter pollutants. Filters pollutants.

Daylighting
Daylighting restores previously piped or culverted streams to their historical condition. An important aspect when daylighting a stream is restoring/protecting a surrounding riparian buffer.

Traditional Design Problems Sustainable Design Solutions
Doesn’t support living systems. Streambeds provide habitat and microorganisms and plants are natural pollutant filters.
Doesn’t manage floodwaters. Restores flood storage capacity.
Conveys water as quickly as possible from the site. Re-connects water to the hydrological cycle.

Turf Alternatives
Providing landscapes with minimal or no turf.

Traditional Design Problems Sustainable Design Solutions
Except for the flattest of areas, turf creates almost as much runoff as impervious surfaces (such as pavement). Meadows & woodlands create 1.5 to 4 times less runoff than turf (depending on the condition of the turf and soil).