Lyle Clemenson (President
of EFI) first became involved in stormwater back in 1991. He
was then, chair of a task force for the City of Brooklyn Park
planning for stormwater runoff. Contaminant romoval was also
Initially, he assumed
that when the plan was finished, it would be simply a matter
of purchasing and installing filtration systems. Then buy filters
needed and to remove the contaminants from stormwater runoff.
To his great surprise
there was no such system.
Being an inventor/engineer,
Lyle began thinking about how the contaminant removal could be
accomplished. Having had a construction company for ten years
and having constructed many catch basin and storm drain systems,
Lyle believed that the obvious place to begin was in existing
catch basins. He looked at many catch basin designs and determined
that the filtration canister's size should be 20" in diameter
and 36 inches long.
Next a medium must
be found that would work in this size unit. There were a number
of options and among those were: sawdust, cellulose, raw pear,
activated carbon, etc. Activated carbon is widely used and raw
peat also works to a degree. However, activated carbon comes
in a granular form and will only allow a limited amount of water
through. Raw peat does a reasonable job of filtering, but also
passes water at very low rates.
After much research
and study, Lyle learned that Bemidji State University had begun
working with sulfinating peat to enhance the removal characteristics
for heavy metals.
Starting in 1995,
working with a consultant from the US Bureau of Mines, they began
research on sulfonating peat. After months of testing and processing
they developed and formulated a process for sulfonating peat,
extruding it, drying it, and sintering it to make pellets that
work for removing contaminants from stormwater runoff. He recieved
a patent for the process in 2000.
The size of the
pellets determines the flow rate and therefore, determines the
quantity of water to flow through the catch basin.
Since mid 1997,
Environmental Filtration Inc., has had a number of canisters
in catch basins in Brooklyn Park, and other cities in Minnesota.
The research, development, and validation continues.