20100752_R-2237C Modification_20161011

Carpenter,Kristi
From:Shown, Marc T
Sent:Tuesday, October 11, 2016 12:52 PM
To:[e-mail]
Cc:Wanucha, Dave; [e-mail]; [e-mail]; amar002
@aol.com; [e-mail]; Fisher, Paul F; Lauffer, Matthew S
Subject:R-2237C Modification
Mr. Marshall,

I am responding to your request for a more in depth explanation of the drainage to be discharged at Bill’s Lane. There
has been no diversion of drainage to the outlet point of the 24” CSP discharging adjacent to Bailey’s Camp
Branch. There has been an increase of approximately 1.0 acres of impervious area in the 6.7 acres that the outfall pipe
is draining. This increase in impervious area will result in an increase in discharge between 2 and 3 cfs when calculated
using the rational method for the 10 year event with a 10 minute time of concentration. The time to peak of this part of
the basin will be reduced, draining it faster, and the overall peak discharge for the basin will be potentially reduced. By
bringing the pipe down the slope and discharging adjacent to the stream the potential for erosion due to larger rainfall
events than would be designed for will be greatly reduced. The stream at the point of discharge is relatively wide with
stable rocky banks and we do not anticipate any variance to this condition. If you have any further questions, please
contact me.

Marc,

Marc Shown, PE
NCDOT Hydraulics Unit
919-707-6751

From: Smarshallcpa \[mailto:[e-mail]\]
Sent: Thursday, October 06, 2016 6:07 AM
To: Shown, Marc T <[e-mail]>
Cc: Wanucha, Dave <[e-mail]>; [e-mail]; Bill Little <[e-mail]>;
[e-mail]; [e-mail]
Subject: Fwd: R-2237C Modification

Marc:

Thank you for the information provided. I do have a rationale / question that I hope you can help me with.

I don't understand the conclusion drawn by comparing the drainage potential of 200 acres of natural drainage through
hills,valleys, ground cover, vegetation and varying soils and distances, to adding the drainage potential of 6 acres from
321 into a 24 inch pipe and sending it down a 250 ft drop in elevation to release at the edge of the trout stream. Saying
that 6 acres is 3 percent of 200 acres therefore this is not impactful leaves me confused.

I trust that Mr.Steele forwarded my 37 page site assessment wherein the stream condition and adjacent pond dams
were discussed? We walked and talked about these areas when he visited with me on site and he asked that I send this
information to him/DOT. My concern remains that this outflow will introduce 2 or 3 times (or more) of the current
natural flow. The impact from handling this increased flow relative to erosion risk to the stream banks, pond dams and
bridge crossing site has to be 2 or 3 times. I do not understand how to factor in that the impact from the concentrated
flow and energy from this pipe is only 3 percent more than what is naturally occurring in the trout stream right
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now. Any explanation that you might offer to help explain to me would me very helpful and appreciated.

Respectfully,

Shannon Marshall
Sent from my iPad

Begin forwarded message:
From: Smarshallcpa <[e-mail]>
Date: October 5, 2016 at 11:58:39 AM EDT
To: "Wanucha, Dave" <[e-mail]>
Cc: "Shown, Marc T" <[e-mail]>, Bailey's Camp Partners
<[e-mail]>, Amy Marshall <[e-mail]>, Bill Little
<[e-mail]>, Jody Little <[e-mail]>, [e-mail]
Subject: Re: R-2237C Modification
Dave:

Thank you for the work, communication and the information. I will need to get this info to someone
who can independently understand and advise me on the engineering assumptions and interpretation
of flow data.

Is there anything that you can offer relative to water quality of what will be introduced to the trout
waters?

Thank you,

Shannon

Sent from my iPhone

On Oct 5, 2016, at 10:32 AM, Wanucha, Dave <[e-mail]> wrote:
Hi Shannon,
I talked with Marc Shown this morning, the DOT hydrologist that designed the
stormwater drainage system for the permit modification. See the emails below. He
confirmed that stormwater discharged from the proposed pipe would be a small
fraction (~3%) of the overall stormflow that would drain to Bailey’s Creek upstream of
your ponds.

Attached for your review are the data Marc provided during my field meeting on Sept
7. Marc will be happy to talk with you concerning the data. His phone number is 919-
707-6751. Let me know if you need anything further. Thanks.

Dave W.

Dave Wanucha

Division of Water Resources
2

Transportation Permitting Unit

NC Department of Environmental Quality

336-776-9703 office

336-403-5655 mobile

[e-mail]

NC DEQ Winston Salem Regional Office

450 West Hanes Mill Road, Suite 300

Winston Salem, NC 27105

<image005.png>

Email correspondence to and from this address is subject to the

North Carolina Public Records Law and may be disclosed to third parties.

From: Shown, Marc T
Sent: Wednesday, October 05, 2016 9:56 AM
To: Barrett, William A <[e-mail]>
Cc: Wanucha, Dave <[e-mail]>
Subject: RE: R-2237C Modification

Dave,

You are looking at it correctly. The reason that the discharge from the pipe looks large
compared to the overall drainage area is due to the methods used to calculate the
discharges. Rational method was used to calculate the discharge for the pipe and Rural
regression equations were used to calculate the discharge for the overall drainage
area. The rational method was used for the pipe as it is conservative and keeps our
pipes out of pressure flow situations and accounts for the faster runoff due to
impervious area and channelization. The rural equations look at the entire basin and
the time of concentration for the basin will be larger than that for the pipe therefore
reducing the peak discharge. Let me know if you need anything further, My # is 919-
707-6751.

Marc

From: Barrett, William A
Sent: Monday, October 03, 2016 10:51 AM
To: Shown, Marc T <[e-mail]>
Cc: Wanucha, Dave <[e-mail]>
Subject: FW: R-2237C Modification

Marc,

I received the email below from Dave Wanucha with DWR. Can you provide a response
to his question?

Thanks
Bill
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From: Wanucha, Dave
Sent: Monday, October 03, 2016 10:47 AM
To: Barrett, William A

Subject: R-2237C Modification

Hi Bill,
I’m reviewing the data you provided while in the field Sept 7 (see attached) and need to
clarify drainage areas in regards to the Bill’s Lane outfall (Site XIV).

Your data estimate that the entire drainage area to Bailey’s Creek upstream of the
outlet at 204 acres, and the Q10 based on USGS regression would be 125 cfs. The
proposed 24” outlet will drain just 6.7 acres (roughly 3.0%) of that total, and the Q10 for
the proposed 24” outlet is estimated at 21 cfs. Am I interpreting that correctly?

Dave W.

Dave Wanucha

Division of Water Resources

Transportation Permitting Unit

NC Department of Environmental Quality

336-776-9703 office

336-403-5655 mobile

[e-mail]

NC DEQ Winston Salem Regional Office

450 West Hanes Mill Road, Suite 300

Winston Salem, NC 27105

<image006.png>

Email correspondence to and from this address is subject to the

North Carolina Public Records Law and may be disclosed to third parties.

Email correspondence to and from this sender is subject to the N.C. Public Records Law and may be disclosed to third

parties.
<Outfall data.pdf>
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