Learn how a permeable parking lot became the star of a new park. In the spring of 2002, the City of La Center, Washington hired Gibbs & Olson, Inc. to review the feasibility of constructing a parking lot along the north side of 4th Street across from the La Center City Park. The lot would provide additional parking for the City Park for high-use events such as ball games, soccer matches and public meetings. With La Center High School approximately 700 feet to the north, the parking lot would also provide supplementary parking for extracurricular school activities such as sporting events and club functions.
A Permeable Parking Lot Was The Solution to Managing Stormwater Runoff
The project involved developing approximately 100 parking spaces with a middle access lane and parking on each side. The existing site was primarily grass. One of the main issues for this project was stormwater runoff. La Center code for storm drainage requires that post-development runoff rates not exceed pre-development rates. Utilizing rainfall information from the area, it was determined that approximately 5,000 cubic feet of storage was required for the proposed design based on a 10-year storm event. Initially, two main alternatives for providing the necessary storage were evaluated: detention pond and pipe storage. While evaluating the first two options and finding a number of construction challenges for both, a third option, permeable pavers, was found in an issue of Stormwater Magazine that talked about a permeable parking lot. An email address in the article led Gibbs & Olson to Mutual Materials, and to the consideration of Uni Ecoloc® permeable pavers as a viable alternate solution for stormwater management. It offered an option that avoided the potential hazard and aesthetic undesirability of a detention pond as well as the drawbacks of pipe storage, including difficulty in obtaining sufficient groundcover and underground storage drainage issues and utility conflicts associated with pipe storage.
Multiple benefits of using the Uni-Ecoloc® system were realized
• The lot was mechanically installed, which, for the size of the project, is more economical than manual installation.
• Because the depth for the interlocking pavers was held constant for the area of the parking lot at only 15 inches, little conflict with the existing utilities was evident.
• In the event future work on one of these utilities be necessary, they can be accessed by removing the pavers and aggregate, excavating and repairing the utility, and then replacing the aggregate and pavers. This results in a tremendous savings to the city and the utility companies, while also preserving the appearance of the finished surface.
• Water runoff into ditches adjacent to the parking lot was reduced. In addition, the system provided water quality
treatment to the runoff, reducing pollutant and sediment contamination of downstream bodies of water.
• The pavers provided a high-strength, durable pavement surface.
• Alternating space colors—no need for painted stripping.
The permeable parking lot was completed on time and on budget. While the upfront cost of the Uni-Ecoloc® solution was greater than that of an asphalt and storm drainage pipe system, when taking the life cycle cost into consideration, the cost difference is negligible. Over the typical 20-year life cycle of an asphalt surface, costs will be incurred at regular intervals for such things as restriping, repairs, maintenance and resurfacing.
In contrast, the load bearing life of the Uni Ecoloc® system is 30 years. With the only maintenance being vacuuming of the voids every 1–4 years. “People in the Northwest are increasingly putting a higher value on solutions that are environmentally sound,” noted Brian Crooks of B.C. Paver. “Combined with long-term economic value, our solution offered the City a clearly superior choice.”
If you’re looking for a basic understanding of permeable pavers for permeable parking lots, check out our blog, Introduction to Permeable Concrete Paving.
If you want to get even more in-depth here are some more resources to help explain how permeable concrete paver system works.
Mutual Materials have a full line of permeable pavers for both residential and commercial applications.