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A Porous Walk in the Garden
Garrett Churchill, Inc., Installs Permeable
Hardscape with Porous Pave

By David Aquilina, Strategic Storyteller


At the Samuel A. Green House in Elkins Park, Penn., Garrett Churchill, Inc., a top landscape design/build company in the Philadelphia region, designed and installed the five-foot-wide walking paths and a 24-foot diameter patio in the Gil Rosenthal Garden of Peace.


The centerpiece of the patio is a recirculating water feature that utilizes slabs of granite, which are a reclaimed architectural element from demolition on the site. The core-drilled granite sits on a prefabricated fountain basin that houses the pump, valves and tubing required for the water feature.

Garrett Churchill, Inc., a landscape company serving the Philadelphia region since 1999, designed and installed the Gil Rosenthal Garden of Peace at the Samuel A. Green House, Elkins Park, Penn. Managed by Federation Housing, Samuel A. Green is a low-income housing tax credit building with 84 one-bedroom apartments for the elderly. The garden offers residents and neighbors a green space where they enjoy the shade, foliage and flowers provided by seven shade trees, three flowering trees, 120 shrubs, and 150 perennials included in the design. Four paths lead to a central circular patio with wood bench seating. The patio's centerpiece is a recirculating water feature installed in core-drilled slabs of granite, one of the reclaimed architectural elements Garrett Churchill saved and used in the project.

An old mansion had occupied the site. Federation Housing hoped to renovate it and incorporate it into their facility plan, adjacent to the new apartments. The cost proved to be prohibitive for the non-profit organization. The town approved demolition -- if the site would be maintained as a park-like green space.

The demolition created a challenge for Garrett Churchill.

"We had to remove a lot of debris, and the soil was in poor condition," said Andy Sykes, CLP, PCH, owner, Garrett Churchill, Inc. "We supplemented the soil with compost and organic fertilizer to increase nutrient and water uptake."


The site where the garden is located had an old mansion that Federation Housing, the property managers, had hoped to keep and renovate. But it was too costly. To get permission from the town of Elkins Park to demolish it, they had to agree to maintain it in perpetuity as green space for the use of everyone in the town, not just residents of the new senior apartments. Garrett Churchill, Inc., saved and used some materials from the old house in the garden, including this column.



Due to permeable surfacing regulations, and because many elderly residents of the Samuel A. Green House use walkers or wheelchairs, a permeable surface that is also ADA-compliant was required for the garden paths and patio. The Garrett Churchill team used Porous Pave XL batch mixed on site and poured in place at a depth of 1.5 inches atop a four-inch base of compacted crushed aggregate. Once installed, the surface cured within 24 hours.

The new apartment building took up all allowed impervious space, so no additional impervious surface areas were permitted within the garden. Finding the right permeable material for the pathways and patio, and meeting requirements to retain stormwater on site, presented difficult problems.

"The average age of Samuel A. Green residents is 80. To get out and enjoy the garden, they need a solid, stable, non-slip surface that is easy to navigate with walkers and wheelchairs. That ruled out gravel," said Sykes. "The paving material also had to have more porosity than permeable pavers. Otherwise, we would have been forced to install additional stormwater retention features at grade, adding costs and detracting from the landscape."

Sykes considered Porous Pave XL, a highly porous and durable pour-in-place paving material made from 50 percent recycled rubber chips and 50 percent kiln-dried aggregate mixed with a liquid binder, as a possible solution. He had completed training at Aquarius Supply, Norristown, Penn., to become a certified installer but had not yet had the opportunity to use it.

"With 27 percent void space, the material infiltrates more stormwater than permeable pavers," said Sykes. "It forms one continuous, consistent, solid rock-rubber permeable surface, and the rubber content gives it good traction while making it freeze- and frost-heave resistant to eliminate the risks of heaving and cracking."

Sykes and a five-man crew installed a total of 1,650 square feet of permeable walkways and patio. As the first step, they put down and compacted a four-inch base of crushed aggregate. Then they batch mixed the granite rock and rubber chips with the binder in a portable mortar mixer. Every 50-lb bag of rock plus a 50-lb. bag of rubber, mixed with five quarts of binder, yielded 16 square feet of material for installation at a 1-1/2-inch depth. Sykes advises careful measurement of the binder so the exact same amount is used in each batch.

"It was easy to install and finish with bullfloats and trowels," said Sykes. "I already specified it for another job." "The garden is a place of beauty and peace, and the pavement makes it accessible and safe," said Jane Lahage, NAHP-e, director of operations, Federation Housing, Inc. "The color and texture of the material complements the building and blends with the landscape created by Garrett Churchill."

As seen in LC/DBM magazine, September 2017.

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August 25, 2019, 5:48 am PDT

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