MA1009-CS130426
Rhonda Adloo
From:Kyle Dykes <KDykes@TNPINC.com>
Sent:Friday, April 26, 2013 3:49 PM
To:Keith Marvin; John Elias
Cc:Alberto Samaniego; Tim May
Subject:Geoweb Infill - Clarification
Gentlemen,
As a follow-up to our site meeting this morning I wanted to document what I saw and clarify my recommendation. The
backfill that has been placed above the proposed water level appears to be approximately 1-1/2” rock (ungraded), with
a small amount of soil mixed in. After revisiting the specification, I see that 3/8” to 1” rock, blended with pulverized
topsoil and 30% voids is called for in cells to be vegetated.
Clarification:
I did not recall having aggregate in the vegetated area of the Geoweb, which is why I was so surprised to see the large
rock. The aggregate mixture is probably more necessary on channel banks and larger lakes that would see direct flow or
heavier wave action. In this case the aggregate would probably be beneficial but doesn’t need to be quite so large. I
apologize for any confusion I may have caused this morning by not understanding the issue better. Also, I need to clarify
that I do not want to dictate what happens on the construction site. I definitely want to be there for you guys in
resolving issues and assisting you with making decisions, but my involvement needs to end at design, clarification,
and/or recommendations. By no means do I want to make the call to stop construction or order materials to be
removed and replaced.
Recommendation:
Even though I feel what’s in the ground may not meet the specification, I’m not sure it needs to be removed. One
alternative would be to level off the aggregate mixture to the top of Geoweb, and place 2” to 3” of topsoil above it. As
for the vegetated cells that have not been filled yet, I recommend smaller rock aggregate (1/2” approx..) and a minimum
of 50% topsoil. That said, I don’t see the aggregate infill above the water level being critical along the lake edge where it
will only see light wave action. I think topsoil backfill alone is sufficient.
Please let me know if we need to discuss further. Thanks
Kyle Dykes, P.E., CFM
StormWaterGroup
1100 Macon Street
Fort Worth, Texas 76102
817.336.5773 Main
817.665.7171 Direct
kdykes@tnpinc.com
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