20070932 Ver 1_Email_20060426

Re NC 43 connector ICI
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Subject: Re NC 43 connector ICI
From: Colin Mellor <cmellor@dot state nc us>
Date: Wed, 26 Apr 2006 13 37 26 -0400
To: Brian Wrenn <bnan.wrenn@ncmail net>
CC: LeiLam Paugh <lpaugh@dot state nc us>, John Hennessy
<John Hennessy@ncmail net>
Brian,
here are some "answers" to the comments you emailed concerning Bosch Blvd
1) the Table in the Exec Summary are aggregated totals for the seven year study
period
2) The purpose and need of the project is to help economic development for Craven
County Specific objectives and an associated TIP project are mentioned in the
Introduction (p 1-1) In addition to the big picture economic goals, I believe Bosch
Blvd is so named for the Bosch (as in power tools) factory that is either or has
expanded or built new facilities (I need to check on this but I read or heard it
somewhere)
3) Section 4 3 1 (p 4-10) provides reason and rationale for rainfall inputs
4) I had a similar question when first reading the report I'm assuming you have the
corrected version but here is my original comment and response from Stantec.
Comment: Section 4.5 5 - It seems accumulation rates should be increasing with
imperviousness. Roads are at the low end of this range?
Response: According to the data from Kuo et al (1988), suspended solids
accumulation rates do increase with imperviousness for residential land uses,
particularly on the impervious surface itself (see page 115 in the GWLF manual)
However, commercial and industrial land uses have lower accumulation rates than
the high-density residential land uses (RHH and RVH) So your comment is
generally correct
The text in Section 4 5 5 will be modified as follows
In the model application, sediment accumulation rates by land use ranged from 1 8
to 3 7 kilograms per hectare per day (kg/ha/day) These rates were based on
suspended solids accumulation rates from Kuo et al. (1988) as cited in Haith et al
(1982) Rates for residential land uses ranged from 1 8 to 3 7 kg/ha/day, with values
increasing with imperviousness Rates for nonresidential land uses including
5/18/2006 9 46 M
Re NC 43 connector ICI
commercial and institutional categories were 2 2 to 2 5 kg/ha/day
Note that the iterative adjustment in the model was to bring the export value in line
with FHWA and USEPA values (p4-16)
5) I'll have to claim ignorance on this one My understanding of stormwater
management (which could be fit into a thimble) usually equates to retention ponds
Therefore I thought the " little impact on long-term runoff rates or
volumes control is considered implicitly " comment made sense I have forwarded
this comment to Stantec and will forward their response
6) Similar sections on stream erodibility seem to be included on all ICE/ICI
reports I'm not sure why While I will not disagree that hydrograph data may
become a little more flashy, lack of topography and wide floodplains in the coastal
plain mean that mstream water velocities remain low and increased stream erosion is
unlikely
I will forward Stantec responses when I get them I am Oak Island swamped for the
next couple of days Hopefully this answers some of your concerns
Colin Mellor
PDEA - Natural Environment Unit
N.C Department of Transportation
919-715-1426
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