Pervious Pavement Alternative
On May 20, 2009 the Grants Pass City Council adopted Ordinance 5489 (PDF) amending Section 25.031 of the Development Code to allow pervious surfacing materials to be used in parking and vehicle maneuvering areas. The amendment provides options to homeowners and commercial developers to choose a more environmentally-friendly alternative to non-porous asphalt or concrete for driveways and parking lots.
Since impervious pavement is the primary source of stormwater runoff, Low Impact Development (PDF) strategies recommend permeable paving for parking areas and other hard surfaces. Permeable paving allows rainwater to percolate through the paving and into the ground before it runs off. This approach reduces stormwater runoff volumes and minimizes the pollutants introduced into stormwater runoff from parking areas.
Benefits of Pervious Surfacing
- Lower surface temperature and ground level ozone
- Minimize flash flooding and standing water
- Mitigate surface pollutants and prevent polluted water from entering our river and streams
- Provide protection for trees
- Reduce stormwater run-off and eliminate the need for detention ponds and other costly stormwater management practices
- Replenish water tables
Permeable Paving System
All permeable paving systems consist of a durable, load bearing, pervious surface overlying a crushed stone base that stores rainwater before it infiltrates into the underlying soil.
Permeable paving techniques include:
- porous asphalt,
- pervious concrete (PDF),
- paving stones (PDF), and
- manufactured “grass pavers” made of concrete or plastic (PDF).
Permeable paving may be used for driveways, walkways, patios, plazas, parking stalls, and overflow parking areas. See the list of resources (PDF) for technical details.
Pervious Pavement Approval
Pervious surfacing materials such as concrete, grasscrete, or paved tire strips can be approved for use in the City of Grants Pass following review and approval by the City Engineer. T
he type of surfacing material and the location where it will be used should be indicated on your site plan. In some cases the City Engineer may request a copy of the product manufacturer's specifications for use and installation, or engineered drawings showing how the system will work.
The pervious surfacing material must have similar structural characteristics to asphalt or concrete, and be capable of withstanding the normal wear and tear associated with the parking and maneuvering of vehicles. In addition, drainage should not adversely affect the public right-of-way or adjacent properties and the pervious material must be maintained throughout its use so that it continues to function as originally approved by the City Engineer.
View the case study of Horizon Village Retirement Community (PDF), which uses grassy pavers for access drive.