Design, Construction, and Maintenance

Discover Penn State Extension’s resources on stormwater management design and construction. Access practical information on rain gardens, green roofs, rainwater cisterns, and toolkits for water resource managers. Tips on planting green infrastructure as stormwater control systems can be found as well.

Stormwater Runoff: Construction and Design Tips

Stormwater control systems are important for successfully managing surface runoff. In urban areas, stormwater runoff cannot infiltrate the impermeable surfaces, making these systems essential.

Most control systems are designed to store runoff water, recharge groundwater, and use water for household and/or irrigation purposes. Common stormwater control options for property owners include permeable pavers, as well as rain barrels and cisterns.

Rainwater Cisterns

Cisterns and rain barrels are structures used to capture and hold water from rooftops until it can be used or released into planted areas. When designing a cistern, remember to calculate the amount of water that can be collected from the roof. This can be estimated by using a formula such as (inches of rain per rain event) x (Square ft. of the roof) x (0.6 conversion factor) = gallons to rain barrel per rain event.

Pervious Surfaces

Permeable pavers are installed with a thick stone base, allowing space for water to be stored until it’s absorbed into the ground. In order to work properly, porous pavement and permeable pavers must be constructed over a carefully prepared subsurface. This can be graded wash stone, but it may also include storage tanks, basins, and piping. The construction costs for your stormwater project will generally depend on the technology and size of the control system.

In this section, find tips on creating infiltration surfaces and using green infrastructure. Discover creative ways to manage stormwater with the free Artful Rainwater Design webinar, as well as the homeowner’s guide to stormwater.

Rain Garden Construction

Rain gardens are an excellent option for slowing and reducing the amount of stormwater runoff from downspouts, driveways, and other impervious surfaces. Rain gardens have a bowl shape that enables them to capture water and let it soak into the ground.

Factors to consider during rain garden construction include location and size, soil type, water flow, and types of plants. It’s important to place the garden where it will collect the most runoff. It is recommended to construct rain gardens at least 10 feet from a foundation, 50 feet from a septic system, and 100 feet from a well.

Green Roof Design and Construction

Vegetated roofs, or green roofs, are a low impact development practice recognized for reducing stormwater volume and runoff peak rates. Other benefits of green roofs may include extended roof life, improved air quality, and stormwater attenuation.

Green roofs work by capturing and retaining water, which is later evapotranspired back to the atmosphere. In general, there are two main types of green roofs – intensive (large vegetation) and extensive (small vegetation).

The general design of green roofs includes four layers – roof membrane and root barrier, drainage layer, growth media, and adapted vegetation. Discover further construction and design considerations during the Green Roofs Management webinar.

Stream Restoration Practices

Stream restoration involves the use of various methods specially designed to reduce erosion and improve stream health. Practices that can add plant life back to the streams often include live staking and riparian buffers.

Live staking can be an affordable method for restoring eroding stream banks. It is used to reintroduce plant life directly on the stream banks. Live stakes – the stem cuttings taken from trees during the dormant season – are inserted directly into the banks.

Using a riparian buffer is another practice that involves planting trees and seedlings along the stream. Planting riparian buffers can help hold soil in place, soak up nutrients, absorb rainwater, and provide wildlife habitat.

On this page, discover more about stream repair and stormwater runoff management practices. Advice can be obtained on planting stormwater control system, as well as on the ecology of streams and forested buffers.