20081304 Ver 3_Emails_20081211

Treyburn walking trail - DWQ comments
Subject: Treyburn walking trail - DWQ comments
From: "Alan Pytcher" <[e-mail]>
Date: Thu, 11 Dec 2008 16:35:39 -0500
To: <[e-mail]>
Amy,
Please find the email sent to us from Joseph Gyamfi regarding his comments
for Treyburn Walking Trail Phase I.
Please send me an official comment letter from the comments below, and we
will make the necessary revisions, and return a copy of the plans to you
ASAP. Again, we are only asking for Buffer Authorization, and wish to gain
approval as quickly as possible.
Thank you for your time.
Alan
SUMMIT CONSULTING
ENGINEERING-ARCHITECTURE-SURVEYING
Alan Pytcher
Planner
1000 Corporate Drive, Suite 101
Hillsborough, NC 27278
Phone: [phone] Ext. 130
Facsimile: 919.732.6676
Please consider the environment before printing.
-----Original Message-----
From: Joseph Gyamfi [mailto:[e-mail]]
Sent: Tuesday, November 18, 2008 3:46 PM
To: [e-mail]
Cc: Alan. Pytcher; Manu. Castel; Edmund Purcell
Subject: Re: Treyburn walking trail
Hello Tracy,
This is to acknowledge receipt of your email. My conversation with you was
based on a quick review of the swale/ditch information. After further
review, please consider the following points in your revision:
* The drainage area of 7B is greater than that of 7A. Please
indicate the outfall of 7B. If 7B has a separate outfall, the
velocity should be reduced to below 2fps or consider using level
spreader. If 7B drains to 7A, then the design calculations of 7A
would not be correct, and need to be revised to include flow from 7B.
* Similarly the design calculations for 4A (downstream) should be
analyzed taking into consideration drainage areas of or flows from
upstream channels 4A and 4B.
* Please indicate the slopes in the buffer following the outfalls in
channels 4A and 7A. (Using a scale of 1" : 401, I am getting
approximately 8% for 7A buffer and 7% for 4A buffer). Which means
that the water flows from a steeper slope in channel 4A (9.10)
into a little bit flatter slope (7%) in the buffer. On the other
hand, water will flow from a much flatter slope 4.7% to 8% in the
buffer). You may have to tie both 7A and 4A to the existing
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Treyburn walking trail - DWQ comments
channels on the other side of the trail, or you may have to
install a level spreader to follow the contours on the same side
of the channels, especially when the upstream drainage areas or
flows have been accounted for in the design calculations of the
downstream channels.
* Include photos of the existing vegetation in the buffer at the
outfall of channels 4A and 7A.
* With respect to channel 5, you could still discharge into the
existing channel as you propose. However, it is still required
that the 10-year storm velocity prior to discharging into the
existing channel shall be less than 2fps. So please consider
revising channel 5 as well.
Let me know if you have any question. Thanks.
Joseph.
Tracy Parrott wrote:
J,
Per our discussion, here is a list of the issues I will clarify and/or
resolve:
* Review and clarify cut/fill slopes. The typical section shows
2:1 and the channel calculation chart shows front & back slopes
of 3.:1.
* Add note to erosion control sequence (note #12) to address the
installation of ditch liner per channel chart.
* Verify the slope of Channel 4B, currently shown as 22%.'
* Channels 4A & 7A outlet into the existing buffers. Diffuse flow
needs to be achieved through the buffer, unless the outlet
velocity can be reduced to less that 2 fps. We will consider
modifying the ditch slopes to reduce the outlet velocity.
otherwise, we will consider level spreaders to achieve diffuse
flow. Hopefully this can be avoided.
Please acknowledge receipt and agreement with this listing. I
understand that review comments will officially come from Mr. McMillan
who is reviewing the stream impact map. Thanks for your call and
input. TNP
* *
*Tracy N. Parrott, PE*
Project Manager
1000 Corporate Drive, Suite 101
Hillsborough, NC 27278
Phone: [phone] Ext. 138
Facsimile: 919.732.6676
www.summit-engineer.com <http://www.summit-engineer.com>
P* Please consider the environment before printing.*
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