North Point State Park Permeable Paving in Baltimore, MD



Case study in budget-friendly permeable paving

A gravel parking lot in North Point State Park had become rutted due to stormwater damage. Maintenance and repairs to fix the reoccurring issues had become costly, causing the client to consider other permeable parking options.


The client’s goal was to install a budget-friendly permeable paving system with reduced maintenance requirements.



Solution and installation: PowerBlock

After experiencing many issues with the gravel lot, the client was interested in using permeable pavers to create a more formal parking surface that would allow infiltration and reduce maintenance.


As the lot was 1.7 acres, the engineer decided to use asphalt and pave the driving lanes at a pitch toward the parking spots that would feature PowerBlock open-joint permeable pavers (approximately 25,000 square feet throughout the lot).


While PowerBlock pavers are capable of providing the required load support to be used in drive lanes, the engineer was able to reduce costs while meeting all necessary regulations by only using the pavers in the 141 parking spots.


The installation included a layer of No. 2 stone for storage with a layer of No. 57 stone over it to assist with both filtration and storage. The layer of No. 7 or No. 8 stone that is often used for leveling pavers is not required with the PowerBlock system, which helps reduce the likelihood of clogging toward the top of the system.


A combination of overdrains and underdrains was also installed to assist in removing water from the system during larger storms.




More than two years after installation, the permeable paving system is still operating as expected with little maintenance required. The leading edges are starting to show signs of clogging, but the water is able to flow past these edges to achieve the desired infiltration rates (1,000 inches per hour).


While the system doesn’t usually require vacuuming for five to 10 years, we have recommended that it be vacuumed every three years to clear the leading edges before the compaction becomes extremely difficult for maintenance to remove.


As the system uses open-joint pavers, the maintenance is limited to simple vacuuming, and the joints will not need to be refilled with stone.


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