As the sustainability and economic impact of residential and commercial developments become increasingly important in our society, homeowners, developers and government officials look to landscape architects who can offer environmentally-friendly solutions that are both cost-effective and aesthetically pleasing. In an industry that is consistently developing innovative ways to be more efficient and environmentally responsible, landscape architects are looking to a method that has been used since the Roman Empire. Permeable paving methods have been used for thousands of years, but only recently have landscape architects started to use this method to market themselves as eco-savvy.
Each type of permeable paving material has its advantages and disadvantages. In terms of cost, gravel is the least expensive. However, it requires frequent maintenance and renewal, which over time, adds up to a higher cost for materials and labor. Permeable concrete and asphalt are next in terms of expense, and studies have shown that these materials are prone to clogging, negating their effectiveness. A study conducted by the Metropolitan Engineer’s Council in Denver, CO, showed a complete failure of permeable concrete under freeze-thaw conditions. Due to pervious pavement issues with clogging and vulnerability to freezethaw, the material is not ideal for all situations or climates. In fact, some cities have removed pervious asphalt and concrete pavement because of the problems with clogging and continued maintenance.
Another option for permeable paving is brick, concrete or stone pavers with permeable joints. The permeability and water-flow-through rate is dependent on the porosity of the material in the joints, the size of the joints and the entire substrate design. The joint material should adequately allow the passage of water to quickly drain, possess structural capability to withstand traffic loads and provide horizontal stability to the paving surface. Permeable pavers have the ability to infiltrate rapidly compared to most soils and a conservative approach should be taken in designing the system.
Natural stone materials, such as Porphyry, have been used for centuries throughout the world and have proven to be an excellent choice offering beauty, longevity and low maintenance. Natural stone life cycles are measured in decades with studies showing typical minimum of 60 years. Granites such as Porphyry last for centuries. Porphyry is extremely dense with a porosity of less than .6%. Using it in a permeable setting system requires the same pervious materials for the joints and attention to the details of the substrate discussed earlier, but offers an unparalleled surface for durability, low maintenance and overall functionality. The natural surface also meets the American Disability Act (ADA) for slip resistance and smoothness and is inert to chemicals.