| By reducing urban runoff, we can help reduce creek pollution, erosion, and flood severity, and put more water into the soil where it provides a better growing environment for plants and recharges groundwater. Techniques to retrofit existing infrastructure and design new development to keep more runoff onsite are shown below. If implemented on properties throughout the watershed, this approach would help recreate a more natural hydrologic cycle in our urbanized environment. |
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| Creek-friendly techniques to absorb rainwater and reduce runoff |
Increase permeability of driveways,
patios, walkways, and parking areas |
Direct rainfall from rooftops
to landscaped areas |
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Wheel tracks, also known as “Hollywood driveways,” can be used in place of full-width asphalt or concrete driveways.
Local examples: 725 Homer Avenue and 735 Homer Avenue*, Palo Alto. |
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If your yard has clay soils, direct rooftop runoff to a rain garden, a landscaped area built with highly absorbent soil and set in a shallow depression where runoff collects. A rain garden can also be used to absorb runoff from paved surfaces and reduce ponding in yards with poor drainage. |
Local examples: 735 Homer Avenue*, Palo Alto (rain garden absorbs downspout runoff) and Menlo Park Parking Plaza #5* (biofilter absorbs parking lot runoff). |
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Pervious concrete contains air pockets that let rain trickle through to the soil below. Use a layer of crushed rock beneath the concrete to increase the amount of water that can be stored while it slowly percolates.
Local examples: Menlo Park |
| Parking Plaza #5* (southeast of Santa Cruz Avenue between Crane and Evelyn Streets), and 367 Addison Street, Palo Alto (driveway of the historic Hewlett-Packard garage). |
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Roof runoff can also be captured in a rain barrel and used later for irrigation. Because of West Nile virus concerns, ask your county vector control office about standing water regulations and recommendations before installing a rain barrel or cistern. |
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With sufficient spaces between blocks, unit pavers allow rainwater to pass through to the ground below. Open spaces can be planted or filled with gravel. A layer of crushed rock under the pavers is recommended for clay soils.
Local example: 735 Homer Avenue*, Palo Alto |
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If the runoff from your roof is piped directly to the storm drain, consider disconnecting your
downspouts from the storm drain. Instead, direct water to landscaped areas where it can soak into the soil. Use downspout extensions and splash blocks to keep water away from the building foundation. |
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Resources
Low Impact Development Center
www.lid-stormwater.net • Excellent design information for a variety of runoff reduction techniques.
www.lowimpactdevelopment.org • Homepage of the organization.
Center for Watershed Protection
www.cwp.org • Thorough research and resources about many watershed issues.
www.stormwatercenter.net • The “Stormwater Manager’s Resource Center” part of the website, with useful fact sheets.
Environmental Protection Agency
www.epa.gov/owow/nps/lid • This page on low-impact development contains fact sheets, study results, and a good resources list.
Treepeople
www.treepeople.org • The About Us section contains information on several completed demonstration projects that retain, absorb, and reuse runoff. For the residential project, select “T.R.E.E.S. Project”; for the school project, select “Open Charter Project.”
www.sunvalleywatershed.org • Treepeople is currently working on designs for a whole district of
the San Fernando Valley.
Puget Sound Action Team
www.psat.wa.gov/Programs/LID.htm • Description of low-impact development principles, and lists of storm water studies and resources.
Bay Area Stormwater Management Agencies Association
www.basmaa.org • Includes “Start at the Source,” a useful guide for anyone considering a runoff reduction project. Look under “List of all documents” in the Meeting Documents & Technical Reports section. |
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