In 2014 Todd Wacome delivered this presentation at the Portland Oregon StormCon. The talk focused around stormwater treatment issues and the unveiling of novel approach to stormwater filtration at the catch basin level.

1. Todd Wacome
Wynwood Associates
Andover, MA.
Using Standard and Retrofit Catch Basins for
Rainwater Harvesting & Non-Blinding Groundwater
Recharge

2. Why I’m Here
‣ Developed a MASTEP reviewed technology.
‣ First technology in a new category.
‣ MaDEP approves of for meeting treatment
and recharge standards.
‣ Commission members are asking for
more, looking for more.
‣ The SiltPrison can solve problems - yours,
theirs, and DPW’s

3. ‣ Custom homebuilder, designer, and
developer of small projects.
‣ Involved in a broad range of activities
related to land development
‣ Concerned with orders of conditions, site
monitoring through the life cycle of
developing a subdivision.
‣ Curious about the lack of focus catch
basins
Background

4. An appreciation for clean & safe water

5. ‣ Inlet protection now required
but in the way after
construction.
‣ Inserts can’t handle large flows
‣ Deep sumps help, but don’t do
enough.
‣ Most of the problem is with fine
particles in the built
environment.
Inlet grates and catch
basins are ignored

6. A Typical catch
basin in section
view

7. A Typical catch
basin in section
view

8. A Typical catch
basin in section
view

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17. A Typical catch
basin in section
view

18. A Typical catch
basin in section
view

19. Catch basins need to handle high flows

21. Started experiments with cone
shaped filters
‣ Open top and open
bottom
‣ Cone shaped so inner
side of fabric is “upside
down”
‣ Graduated flow rates
using different fabrics
‣ Utilize full volume of
catch basin

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What’s Actually Happening?

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31. Looking down
through an
inverted cone
filter from
street level
between
scoops during
a cleanout
process

33. Inverted cone filtration has
shown remarkable performance

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41. What Are They Testing For?
‣ Testing requirements
have become
extremely strict. Now
Lab testing is very
expensive.
‣ To determine three
main characteristics:
• Hydraulic Capacity,
• Removal Efficiency
• Re-entrainment

42. What Was Determined?
‣ Sediment testing utilized the New
Jersey Corporation for Advanced
Technology (NJCAT) specified
protocol sediment, with a PSD of
1 to 1000 microns and a specific
gravity of 2.65.
‣ Hydraulic testing was performed
on the unit for flows ranging from
25 to 857 gpm. The maximum
flow capacity of the 25-micron
skirt was approximately 400 gpm
(11.25 gpm/ft2).
‣ The maximum treatment flow
prior to bypass was
approximately 675 gpm (15
gpm/ft2). The unit did not
surcharge at maximum flow.

43. What Was Determined?
performed at flows
ranging from 0 to
475 gpm, with an
initial sediment
loading of 100% of
the stated unit’s
capacity using the
NJCAT sediment
PSD of 50-1000
microns.
‣ The sediment bed
was prepared with
a flat profile.
‣ The maximum
average sediment
concentration,
adjusted for
background, was

44. What Was Determined?
48.2% to 78.6% for
the sampling
methodology, with
combined averages
ranging from 44.9%
to 75.9%.
‣ The average
treatment removals
were 83.1% through
the 25-micron skirt
and 73.4% through
the 212-micron skirt.
An average removal of
60.9% was measured
in bypass.
‣ Testing of a partially-
blinded skirt at 10
gpm flow resulted in

64. Recharging Filtered Water:
‣ Water through blue region has
been filtered <20 microns.
‣ Add a “Separator skirt” to
isolate it from water escaping
through the upper 2 regions
which will discharge through
the “grey pipe”.
‣ Add a port to the
casting(lower) to reroute this
filtered water as recharge.
‣ Infiltration trench will not blind

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85. Todd Wacome
Wynwood Associates
Andover, MA.
Thank you!
Info@siltprison.com
(978) 801-1729