Ecoraster Adds a New Dimension in Permeable Surfacing
Recycled tire rubber fill enhances use in stormwater management
Water, Mitch Whitson will tell you, is why his company, California Filtration Specialists (CFS), exists.
More specifically, protecting this valuable resource, particularly in California, is what CFS was founded on. The Escondido, CA-based firm designs and builds sustainable solutions and products for managing stormwater, improving green infrastructure and treating water.
With a background and experience in construction management, Whitson saw the issues of water runoff, stormwater management and water quality shaped through regulation from stormwater permits in the late eighties and nineties focused on stormwater capture to today’s industrial and municipal water quality requirements, which focus on systems to treat water.
This experience and expertise was vested in Whitson CM, an engineering construction management and general contracting firm that founded California Filtration Specialists in 2015.
“When we really got into construction water quality that led to industrial and municipal water quality and when you’re in that space its all about treatment systems,” Whitson said.
CFS has a large variety of treatment systems including permeable surfacing, biofiltration, tank systems and rain harvesting systems.
Most recently the company has been focusing on permeable surfacing and working with the state of California on stormwater management systems incorporating low impact development and green infrastructure practices.
According to the U.S. EPA, low impact development principles complement, and sometimes replace, traditional stormwater management systems, which historically emphasized moving stormwater off-site with curbs, pipes, ditches and ponds.
Low impact development practices encourage rainwater to soak into the ground where it falls, minimizing the opportunity for water to collect pollutants and reach nearby waters.
What we’re trying to do and what the state of California and really the world is trying to do is infiltrate, Whitson said.
“ We want stormwater to infiltrate, to recharge our aquifers” he said.
“What the state wants us to do is get that water back into the ground, for two reasons: it recharges the aquifer and treats pollutants, so as it goes through the substrate of the soil, the anaerobic activity really cleanses that water so it ends up in the groundwater as a clean, renewable source.
Permeable surfacing is one way to do that, Whitson said.
It’s an EPA-recognized Best Management Practice (BMP), for stormwater and can remove pollutants that would otherwise wash directly into rivers and lakes, he said.
While permeable surfacing (pavers, porous concrete or porous asphalt) has been around for years, it hasn’t always been effective or worked the best, Whitson. Some common problems that have prevented the best use of these systems are clogging, durability and high cost.
“That’s where we’re different,” Whitson said. Coming from a construction management view we knew what engineers and geo-techs look for.”
The company’s search of permeable surfacing products focused on permeable paving systems that made sense, were durable, affordable and easy to maintain.
It led to Ecoraster, a simple low profile technology that created a permeable surfacing low density polyethylene (LPDE) paver grid system made of 100 percent recycled plastic shopping bags.
Because the Ecoraster grid structure is made with LPDE recycled plastic it has a high tensile strength and unlike the more rigid HDPE plastic, it’s not going to become brittle over time and fail.
Whitson said the way the system locks together is really the key to its success–providing expansion joints and design flexibility that allow users to take the system apart when needed to repair underground utilities, and assures the system performs in both hot and cold climates without the thermal expansion that causes most other pavements to fail.
Typically, the Ecoraster grids have been filled with either concrete paver units, crushed rock, or decomposed granite depending on applications. A few years ago, Whitson looked at replacing the concrete blocks in the paver unit with rubber blocks. In the process, he met Denise Kennedy and began exploring the idea of replacing the blocks with a recycled tire rubber fill.
Working with Kennedy, the contract manager for CalRecycle’s Feedstock Conversion Services Technical Assistance and Material Testing Services (FCS) contract, CFS designed three Ecoraster products that replace these fill materials with 3/8 inch recycled tire rubber, calcium carbonite, and binder, creating the new Ecoraster TDP.
Under the FCS contract, CalRecycle provides technical assistance and material testing services to manufacturers. This includes onsite extraction samples of recycled tire rubber collected from the tire derived material (TDM) suppliers and manufacturers to verify the rubber classification and particle size distribution as per ASTM International Standards D5603 and D5644.
“The benefit of the CalRecycle program is that through all the lab testing that CalRecycle did on this product, we now have verified ASTM data and information for engineers to incorporate into their design guidebooks. Whitson said the comprehensive range of tests included all the ASTM compression tests, all the environmental tests on the tensile strength tests, solar testing and more. With this kind of data we can really start to implement this technology and fully utilize the Ecoraster TDP to recharge acquifers, conserve and improve water quality, he said.
Ecoraster TDP grids come in a variety of shapes sizes and colors with the most popular being the E40 and E50 Bloxx models which can be used to create full structural sections that can be installed similar to asphalt concrete pavement, will support whatever load you put on it and can be used wherever any hard surface is used.
It’s 100 percent permeable, both the frame and the recycled tire fill allow water flow—over 3,000 inches per hour per square foot,. It’s also very cost effective. Installed cost of the Ecoraster TDP is around $9/sq.ft-$11/sq/ft including rock subbase, Whitson said.
“What’s neat about the tire rubber fill is you can change the color. You can make it look like asphalt or if you have handicap parking zones, you can go with blue or if you have EV parking lanes you can go with green—you can’t do that with concrete or asphalt,” he said.
Armed with this versatility and the backing of ASTM data from CalRecycle’s FCS contract work, California Filtration Specialists is ready to implement Ecoraster TDP technology to recharge the state’s aquifers and is moving forward with projects in the City of Bakersfield and at the San Francisco airport, Whitson said.
© Scrap Tire News, September 2021