Hinkson Creek Watershed Restoration Project Phase II

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Hinkson Creek Watershed Restoration Project Phase
II
FEASIBILITY ANALYSIS FOR RETROFITTING STORMWATER
BMPs
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NOTES- The Hinkson is roughly 26 miles long, its
watershed is 88.5 sq miles. It is wholly within
Boone county. The stream is considered
perennially flowing below Providence, it is class
C from Providence to Mt Zion Church Rd. The
impaired section begins at Walnut St, just
downstream of I-70.
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NOTES- We have a situation in which we are
looking to reduce the quantity of run-off, and
increase the over-all quality of the run-off
What is the contaminant of concern? The Hinkson
is listed on the 303(d) list of impaired waters
for unspecified pollutants, in a 14 mile
segment downstream of I-70. A variety of
urban-associated chemical constituents
(polycyclic aromatic hydrocarbons, pesticides,
petroleum compounds, and metals) in some
stormwater discharges, and high levels of salts
in snowmelt samples, have been found in the
area. DNR has said they will not target a
chemical pollutant in their TMDL document, but
will instead target the urbanized flow regime.
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Why is this an area of interest/hotspot? Sampling
has documented toxicity in approximately 20 of
stormwater discharges in this area Impairment of
Hinkson Creek begins adjacent to this
area Impervious surface in this area is
expansive, approximately 85 acres within the
Megamarket complex alone
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NOTES-The area of interest is characterized by
large areas of impervious surface, with
significant contribution from parking areas,
rooftops, and roads. This area is roughly drawn,
and is meant to include the Home Depot parcel to
the north and the property lines of the
commercial areas to the west. The eastern border
follows a watershed divide.
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I-70
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NOTES-This area is characterized by coverage with
conventional asphalt parking lots and stormdrains
with some landscaped islands there are several
overgrown concrete drainage channels along
roadsides two small reservoirs are within this
area, one is a several decades old claypit and
there is a large disturbed area that is being
cleared for the installation of detention basins
behind WalMart and Hy Vee.
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What we are looking for in the scope of
services Ideas for retrofitting stormwater
treatment structures or implementing practices
that will give us the most bang for our buck A
ranked list of locations within the area of
interest, including 5 pre-selected spots, that
would be optimal for retrofitting, and the BMPs
that would be most suitable in those
locations. Details on the proposed BMPs,
including possible load reduction, detention
provided, costs, and maintenance A
methodology/rationale for selecting these
locations and BMPs
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What we are looking for in the proposals A
general methodology/rationale for selecting
retrofit locations and BMPs Recent references for
work planning/designing stormwater BMPs List of
personnel working on the proposal, and their
relevant experience Cost of services and timeline
for completion
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How we will use this information We will be
implementing a cost-share program for
retrofitting BMPs in the area of interest. The
feasibility analysis will direct our efforts in
approaching landowners. The methodology for
ranking the BMP locations may be used in other
areas within the City, County, or University.
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www.helpthehinkson.org
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