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Achieving 100 Percent Stormwater Retention
Contractor Installs Permeable Pavement for a New Courtyard Garden

by David Aquilina, Strategic Storyteller

Achieving 100 Percent Stormwater Retention

Meadowood Senior Living, a retirement community in Worcester, Pennsylvania, now features an expanded and enhanced courtyard garden thanks to the collaboration of Eric's Nursery and Garden Center from Mt. Laurel, New Jersey, and Design for Generations, LLC from Medford, New Jersey. A green building product, Porous Pave, which was installed on this patio and walking paths, consists of recycled rubber, aggregate and a liquid binding agent. It is a pour-in-place material that has 27 percent void space, allows up to 5,800 gallons of rainwater per hour per square foot to flow through and permeate down into the underlying aggregate base, and can be used for a variety of paving projects.

Meadowood Senior Living in Worcester, Pennsylvania, undertook a transformation of the retirement community's central courtyard. The new area features a lap pool that can be opened to the outdoors, a variety of seating areas and patios, walkways with a bridge along a stream with a waterfall, a spray jet fountain, kinetic sculptures, a fire pit, and an outdoor kitchen.

Before construction could begin, the team of Eric's Nursery and Garden Center, and Design for Generations, LLC came up against regulations for 100 percent onsite stormwater retention. To satisfy the government requirements, the new garden courtyard includes 8,100 square feet of permeable pavement installed with Porous Pave XL. It is a highly porous and durable paving material made with 50 percent recycled rubber chips and 50 percent aggregate mixed on site with a liquid binder.

Best Practices
Jim Daulerio, the president of Splash Sales & Marketing Inc., which is a distributor of the product, has these tips:
Most contractors purchase the product from dealers in 50-pound bags. On average, a contractor would mix a 50-pound bag of rock and a 50-pound bag of rubber chips with a 5-quart pail of binder. This will yield 16 square feet at 1-1/2-inch thickness.

The product is typically put down in a 1-1/2-inch application for pedestrian or bike trails, but the company recommends thicker sections up to 2 inches for
applications where there will be light vehicle traffic.

Achieving 100 Percent Stormwater Retention

There are two rain gardens, 500 square feet and 350 square feet in size, which are also part of the site's stormwater management solution.

Achieving 100 Percent Stormwater Retention

Fine cut chips of the raw material.

On site, it's mixed for 60-90 seconds in a mortar mixer. The curing process takes 6 hours before it can be exposed to moisture; with 24 hours for full cure.
Contractors don't need to compact it or run a density test on it. Once it's installed at that recommended thickness, the installation is done.

Maintenance Matters
Unlike a traditional pavement, because of its rubber content, installations with this product do not need yearly maintenance in the form of crack sealing or sealcoat applications. It requires even less maintenance than permeable concrete or asphalt.

Every few months, you have to clean any permeable pavement with a street sweeper and take some measures to maintain the porosity. With this product, periodically washing it off with water applied at low pressure from a garden hose is sufficient.

Achieving 100 Percent Stormwater Retention

Achieving 100 Percent Stormwater Retention

The amount of permeable pavement installed was 2,900 square feet in a red color for the recreation patio and 5,200 square feet in a tan color for walking paths. The depth of the pour was 1.5" on top of a 4" to 6" base of dense graded aggregate ASTM 57.

If there is traffic on the product where wheels turn on it, there may be some flaking after a few years. That is the flaking of the rubber content that's dislodging from the binder because of the friction of rubber wheels on the surface. If that happens, contractors can solve the problem by thinning some of the original binder, and then rolling it on to the pavement with a paint roller, or overspraying it with an airless sprayer.

Winning Over the Customer
To evaluate the recommended permeable paving material, the Meadowood project's building committee visited Chanticleer, a public garden near Philadelphia, which completed its first installation of the product in 2013.

"The rainy day we went to Chanticleer was a terrible day to visit a public garden," remembered Jim Mangol, senior director of fitness and wellness at Meadowood. "But the rain gave us the chance to see the material's permeability. There were no puddles on the permeable pavement paths. We brought along a wheelchair, a walker and a folding chair to test them out. We came away convinced we had the right product for permeable paving."

As seen in LC/DBM magazine, March 2019.

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December 13, 2019, 6:32 am PDT

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