HomeMy WebLinkAbout20100752_R-2237C Modification_20161017
Carpenter,Kristi
From:Smarshallcpa <smarshallcpa@aol.com>
Sent:Monday, October 17, 2016 11:09 AM
To:Shown, Marc T
Cc:Wanucha, Dave; will@yadkinriverkeeper.org; BLITTLE410@AOL.COM; amar002
@aol.com; baileyscamppartners@gmail.com; Fisher, Paul F; Lauffer, Matthew S; Eller,
Douglas W
Subject:Re: R-2237C Modification
Mr. Shown:
Thank you for response and information.
Is it fair then for me to say that the proposed infrastructure has maximum capacity to flow 25cfs into Bailey Camp Creek
relative to the Bills Lane PDE?
Regards,
Shannon Marshall
Sent from my iPhone
On Oct 17, 2016, at 8:32 AM, Shown, Marc T <mshown@ncdot.gov> wrote:
Mr. Marshall,
For standard NCDOT design purposes a 24” pipe is used to convey discharges between 13 and 25
cfs. The existing cross-pipe at this location is an 18” cmp. A 24” pipe can convey more than 25 cfs but
the issue is the height of the hydraulic head necessary to get that amount of water into the pipe. In
order to get 40 cfs into a 24” concrete pipe the required head at the inlet would be 6.5 ft. It is not
practical to design storm drain systems with extra depth boxes and the added head would cause
pressure in the pipe leading to future maintenance issues. Our typical storm drain design, for a 24”
pipe, would be based on head measuring about 3.5 ft. or less. The increase in pipe size is due to the
additional width of the roadway and the fact that the portion of the roadway draining to the fill slope is
now being picked up with shoulder berm gutter and piped to the bottom of the slope. I will respond to
your additional questions as well.
Marc
Marc Shown, PE
NCDOT Hydraulics Unit
From: Smarshallcpa \[mailto:smarshallcpa@aol.com\]
Sent: Wednesday, October 12, 2016 6:38 PM
To: Shown, Marc T <mshown@ncdot.gov>
Cc: Wanucha, Dave <dave.wanucha@ncdenr.gov>; will@yadkinriverkeeper.org; BLITTLE410@AOL.COM;
amar002@aol.com; baileyscamppartners@gmail.com; Fisher, Paul F <pfisher@ncdot.gov>; Lauffer,
1
Matthew S <mslauffer@ncdot.gov>
Subject: Re: R-2237C Modification
Marc:
It is my understanding that a 24 inch pipe has capacity to handle 18,000 gallons per minute or 40 cfs. If
the added flow for a 10 year event will result in only 2-3 cfs, why would the currently proposed
infrastructure capacity need to be ten to twenty times larger?
Thank you.
Shannon
Sent from my iPad
On Oct 11, 2016, at 12:52 PM, Shown, Marc T <mshown@ncdot.gov> wrote:
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 \[mailto:smarshallcpa@aol.com\]
Sent: Thursday, October 06, 2016 6:07 AM
To: Shown, Marc T <mshown@ncdot.gov>
Cc: Wanucha, Dave <dave.wanucha@ncdenr.gov>; will@yadkinriverkeeper.org; Bill
Little <BLITTLE410@AOL.COM>; amar002@aol.com; baileyscamppartners@gmail.com
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.
2
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 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 <smarshallcpa@aol.com>
Date: October 5, 2016 at 11:58:39 AM EDT
To: "Wanucha, Dave" <dave.wanucha@ncdenr.gov>
Cc: "Shown, Marc T" <mshown@ncdot.gov>, Bailey's Camp Partners
<baileyscamppartners@gmail.com>, Amy Marshall
<amar002@aol.com>, Bill Little <blittle410@aol.com>, Jody Little
<Jody.little@twcable.com>, smarshallcpa@aol.com
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
3
On Oct 5, 2016, at 10:32 AM, Wanucha, Dave
<dave.wanucha@ncdenr.gov> 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
Transportation Permitting Unit
NC Department of Environmental Quality
336-776-9703 office
336-403-5655 mobile
Dave.Wanucha@ncdenr.gov
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 <wabarrett@ncdot.gov>
Cc: Wanucha, Dave <dave.wanucha@ncdenr.gov>
Subject: RE: R-2237C Modification
Dave,
4
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 <mshown@ncdot.gov>
Cc: Wanucha, Dave <dave.wanucha@ncdenr.gov>
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
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.
5
Dave Wanucha
Division of Water Resources
Transportation Permitting Unit
NC Department of Environmental Quality
336-776-9703 office
336-403-5655 mobile
Dave.Wanucha@ncdenr.gov
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>
Email correspondence to and from this sender is subject to the N.C. 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.
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