Rhode Island Public Transportation Center Goes Permeable

By Leslie McGuire,
managing editor

Every project is different, but typically, a permeable paver installation consists of a layer of Number 2 stone (1/2 to 3 inches) then a layer of Number 57 stone, (3/4 inch), then a layer of Number 8 stone, (1/4 inch chip stone), on top of which the paver sits.
Images courtesy of Alpine Landscape Company, Inc.

The Rhode Island Public Transportation Authority (RIPTA) recently completed an installation in the city of Providence of the largest permeable paver project in New England. The reasons for their choice of pavers that are permeable had a great deal to do with the changing ordinances for stormwater runoff, as well as the availability of better choices in paving products that are sustainable as well as long lasting. Previously an uncleared lot opposite the bus station, a light color blend was chosen to reduce the heat island effect, and match the architecture of the new facility.

 

The site was just under 50,000 square feet. That meant 700 pallets of pavers were needed to complete the job. These L-shaped permeable pavers (see inset) were 8 cm thick. In the end, 64.33 sq. ft. of pavers were stacked per pallet, each of which weighs 2,046 pounds. The grand total was 1,432,200 lbs of concrete.

The L-shape pavers were chosen specifically for heavy duty applications. RIPTA maintains a fleet of 241 fixed route buses, 135 Para Transit vans and 17 Flex vans.

Located across the street from their existing bus facility on Elwood Ave, the new Rhode Island Para-Transit Maintenance Facility will serve the maintenance and operations for the Rhode Island?EUR??,,????'???s Department of Public Transportation. Contributing towards LEED accreditation was the Eco-Optiloc permeable interlocking concrete pavers manufactured by Unilock of New England.

Fleet Construction Company prepared the base by first using a large vibratory roller for compaction. Then screeding equipment was supplied by the installation contractor while one of their supervisors assisted Fleet in the final base preparation.

Regulations regarding stormwater runoff by the Narragansett Bay Commission and a desire to mimic pre-development site hydrology led to the choice of infiltration strategy. The unit pavers were manufactured in a light color blend to reduce the heat island effect, reflect sunlight, and match the buildings architecture. RGB provided the architectural plans for both the building and the engineering of the overall site.

After careful evaluation of several unit shapes, Uniloc?EUR??,,????'???s Eco-Optiloc was chosen for its L-Shape design, which is widely chosen for heavy-duty applications. The tri-axis-designed L-shape provides a superior interlock that resists the rotational, vertical and horizontal loads imposed upon it by the buses and other vehicles. The Eco-Optiloc pavers with a 14mm (1/2?EUR??,,????'??) joint also complied with current ADA requirements.

Once enough of the area had been laid with pavers, Alpine Landscape was actually able to drive the Optimas over them and continue the paving process from the paved surface. As each pallet was laid, they were able to drive over what was already laid to put down the next course of pavers. The Optimas, which is about the size of a Bobcat, is specially made to place a full palette of pavers in one motion. So popular in Europe?EUR??,,????'??+especially Germany?EUR??,,????'??+it is almost like a lawnmower. Every contractor owns one because the look of pavers is very popular
in Germany.

For this particular job, by the time the installation contractor, Alpine Landscape Company, arrived they had to go over the base to make sure it was to spec, confirm that it was ready, and then set up the site so they could set up the Optimas and start.

?EUR??,,????'??The biggest issue we encountered was working out a staging area to get started for the installation,?EUR??,,????'?? says Chris Rosa President of Alpine Landscapes, (see his profile, on page 28) ?EUR??,,????'??At the same time as we were doing the paving work, the brand new repair terminal building was being worked on as well. We tried to position the metal pallets out of the way, but we had to set them up as close as we could to the actual site to avoid staging the pallets on top of the base preparation.

Edge restraints were not required because the paved area was bordered by concrete curbing all around. Permeable paver projects need to be bordered by concrete or granite because spiking into crushed stone usually won?EUR??,,????'???t hold.

Ordinarily, the number of people required to do this size installation by hand, would be a four man crew who would lay 1,000 to 1,400 sq. ft per day. With the Optimas machine, that particular product can be laid at a rate of 6,000 feet per day with just an operator and a laborer to make sure the joint lines stay true and they aren?EUR??,,????'???t shifting. That means we were able to cut the crew in half, while accomplishing four times more than a traditional crew could. The first phase took two men nine 8 hour days to complete.

This Uniloc permeable paver was special ordered for this particular project because the L-shape and thickness of 8 cm can support heavy loads and last much longer than an asphalt installation.