What is it?
Conventional pavement and roofs are called ‘impervious surfaces’ because stormwater runs rapidly off of them - leading to polluted runoff, sewer overflows and flooding. Conversely, permeable pavements let rain sink through the pavement and into the underlying soil. A wide variety of permeable pavement options are available for driveways, patios, sidewalks and parking areas, both for businesses and residential owners.
Benefits of permeable paving: • improve drainage • convert soggy lawn to usable space • create contrast in your garden • reduce erosion of adjacent soil/mulch • reduce icy walkways • create fewer puddles
Permeable Paving Options:
Pavers: Any paver or stone can be laid with ¼-1” joint spaces filled with clean, crushed gravel or with a sand/compost mix in which to plant low-growing species like thyme. This method is best used for walkways or patios.
Flexible grid systems: Flexible grid systems are open-celled and may be filled with gravel or vegetation. Properly installed systems may be used for driveways, low–use parking areas, fire lanes or walkways.
Interlocking permeable pavers: A wide variety of blocks and bricks are available and may be used for driveways, high-use parking, patios, and sidewalks. They interlock at the joints, to provide stability and spaces for infiltration.
Pervious Concrete: Pervious concrete is a special type of concrete with large aggregates and no fine particulates, which allows for water to pass through. It is poured in place, is very strong and can be used in almost any application.
It does need to be installed by a professional contractor trained in pervious concrete installation to ensure proper function.
Porous Asphalt: Porous asphalt is similar to conventional asphalt, but without the fine particulates that impede drainage. Porous asphalt is laid in place like regular asphalt and can be installed by any installer, in many applications. However, due to cost restrictions porous asphalt is best for larger paved areas (>10,000 SF).
• Permeable paving is not recommended (and often not feasible) on or near steep slopes and bluffs.
• Sidewalks and walkways are feasible do-it-yourself projects, following instructions from the manufacturer or an expert.
• Seek professional assistance for larger projects - especially for driveways and parking areas.
By supporting the green industry, these practices will become widespread and help to alleviate stormwater pollution into Puget Sound and its tributaries.
Check out our Permeable Paving Resources List at www.betterground.org for locations where you can buy these products and contact information to find qualified installers. The Snohomish Conservation District’s Community Conservation Team can assist you with locating and designing your permeable paving project. Email firstname.lastname@example.org or call 425-335-5634.
Better Ground is brought to you by the Snohomish Conservation District. 528 91st Ave NE Lake Stevens, WA | 425-335-5634 | www.betterground.org
Sound Home Idea #05