20091227 Ver 1_Information Letter_20091215

aR,
=
'0
STATE OF NORTH CAROLINA
DEPARTMENT OF TRANSPORTATION
BEVERLY EAVES PERDUE
GOVERNOR
December 11. 2009
NC Division of Water Quality
1650 Mail Service Center
Raleigh. NC 27699-1650
Attention: Ms. Coleen H. Sullins
Director
Dear Madam,
P s
?'x , ?O
Ot . 09 d
SECRI rARr
IR

Subject: B-4492 Response to NC Division of Water Quality (NCDWQ) Letter
As you are aware, the NC Department of Transportation (NCDOT) submitted a permit application on
November 10, 2009 for TIP project No. B-4492 to NCDWQ. This letter addresses each item in
NCDWQ's December L 2009 letter regarding the replacement of Bridge No. 212 over Reese Creek on
SR 183S (Dunn Rd.) in Cumberland County. Each bullet from the original letter is presented below in
italics, with NCDOT's response immediately following. I have also included an email from Brook
Anderson, from NCDOT's Hydraulics Unit, to Ken Averitte of your office that offers clarification on
some of NCDWQ's questions and will be referred to herein.
The application does not provide any mention-of how this work- will be accomplished "in the dry"
Please submit a detailed plan explaining hoer the site will be dewatered dtaring the course of
construction.
NCDOT does not typically furnish detailed de-watering plans because the information we give to the
contractor is only a reconnnendation. Within the permitted areas, the contractor is free to propose
whichever method they see fit during the actual construction. However, as is required, all work will
be conducted in the dry and overseen by NCDOT Division 6 personnel.
The application does not explain the need for replacement of an existing hridge with a culvert.
Although this rnav be discussed in the CE document, this office has not had the opportunity to review
the CE. At a inhantnm, please provide specific information (cons, consnvetabiliry issues, safety. etc)
disewsink whr this i)ndge cannot be replaced with another bridge.
The current structure is a bridge built in the 1950's. At that time, building a bridge was more
practical than placing a culvert in the stream from several standpoints, including cost, design, and
materials and labor. During the design of this bridge replacement, a culvert was determined to be
hydraulically adequate, illustrated by the fact that the structures used for crossings of Reese Creek
both upstream and downstream of B-4492 are reinforced concrete box culverts (see PCN). In
addition, there are no special aquatic resources present. Generally, the cost of a cored slab bridge is
about twice that Of a culvert (on secondary roads), while a bridge has it shorter life expectancy and
more maintenance costs and opportunities for failure (please see the third paragraph of the attached
email for general cost information). In using a culvert, there is also an opportunity at this site to
alleviate constriction of the channel at the B-4492 crossing, thereby reducing velocities upstream and
MAILING ADDRESS: TELEPHONE: [phone] LOCATION:
NC DEPARTMENT OF TRANSPORTATION FAX: [phone] TRANSPORTATION BUILDING
PROJECT DEVELOPMENT AND ENVIRONMENTAL ANALYSIS 1 SOUTH WILMINGTON STREET
1548 MAIL SERVICE CENTER WEBSITEf WWWNCDOT.ORG RALEIGH NC
RALEIGH NC 27699-1548

allowing the crossing to function better during storm events (see the Fourth paragraph of the attached
email). .
Installation and burial of eulverrs often provides oppornmitvfor development ofa headcut it? the
stream. What measures will be taken to prevent this? Will a sill be used?
Please see the fourth paragraph of the attached email for clarification of this point. And while the
email refers to the originally proposed structure (Z at 13'x 13' RCBQC the sills discussion still applies
to the structure in the PCN (34'x13' ALBC). In fact, the stream should re-establish itself in the
aluminum box slightly quicker than the conventional concrete box double barrel RCBC due to the
additional width and lower velocities which will allow sediment transport material to settle out
slightly faster than what would have occurred in the double barrel concrete box.
The PCV requests approval fa' 45 ft. of tempot-aiy stream impacts. Given that the TS area identified
is upso-eam and clownsn-eam of the requested bank stabilization areas, what will this work involve?
Temporary stream impacts were shown from the ends of the bank stabilization areas to the draina.,e
easements to account for erosion control measures and dewaterinu, activities. "these areas also allow
room for the contractor to take corrective action if any unforeseen erosion control problems occur
during construction. Anything placed in the channel for erosion control or dewatering will be
removed prior to project completion and the channel restored to its natural condition.
If you have any further questions, please contact Amy James at [phone] or [e-mail].
F;1AV1
Greuorv J. Thorpe, Ph.D, Manager
Project Development & Environmental Analysis Branch
cc: Ms. Kim Garvey, USACE
Ms. Sonia Carrillo, NCDWQ
Mr. Jim Rerko, Division 6 Environmental Officer
3am?s, Amy C
From: Twisdale. John W
Sent: Wednesday, December 02, 2009 1:17 PM
To: James, Amy E
Cc: Kluchar. Bryan; Walter, Tracy A, Rivenbark, Chris; Underwood, Chris; Anderson, Brook E
Subject: FW: B-4492
Amy,
Here is what we sent to address Ken's comments in the previous email
Jay
-----Original Message-----
From: Anderson, Brook E
Sent: Friday, March 27, 2009 4:33 PM
To: [e-mail]
Cc: Twisdale, John W
Subject: B-4492
Ken,
I'm working on the hydraulic design for B-4492 (Reese Creek in Cumberland County). Chris
Underwood asked me to contact you regarding the project. I tried to give you a call
today, but was unable to reach you. I will be out of the office on Monday for some field
work so I wanted to try to answer some of your questions concerning the project. I did
speak with Jim Rerko today and he was able to tell me some of your concerns.
Although there is currently a bridge at the project site, there are culverts up and
downstream of the proposed crossing. We have modeled the proposed box culvert and are
able to pass the 100yr discharge without an increase in water surface elevations for that
frequency compared to the existing. According to our model, the proposed design will
decrease the 500yr water surface elevations by approx 0.6 ft. The proposed culvert 2 @
131x13' RCBC is adequate to convey the flow and is larger than the downstream structure at
Pus I-95 which is 2 @ 11'x9' RCBC.
As far as the cost of a culvert versus a cored slab bridge, I don't have any exact numbers
for you. I have checked into some previous projects and it appears that bridges on
secondary roads tend to cost between 1 million and 1.5 million. Culvert costs appear to
be around $500,000 - $700,000. Maintenance costs for culverts are also lower than for
bridges. To get more exact numbers, we would have to determine a required bridge length,
and get the structures unit to provide us with estimates for the bridge and the culvert.
We are not utilizing sills in the box culvert. We sometimes use sills to retain bed
material in buried culverts that have steeper slopes or higher velocities. This culvert
has a minimal slope, and lower velocities, so sills aren't required to retain the bed
material. We also sometimes use sills to direct low flow into a single barrel in order to
keep the flow width through the culvert similar to the flow width of the channel. The
normal flow width at the inlet of the proposed culvert is approximately 14 feet with a
normal flow depth of approximately 2.5 ft. However, based on our field surveys, the
stream is more constricted at the structure location than it is in areas up and downstream
cf the culvert. We also noticed higher water velocities in the area just upstream of the
existing bridge due to this constriction. By allowing the normal flow to pass through
both culvert barrels, the velocities in the vicinity of the culvert and through the
culvert will be reduced, without making the channel width significantly different than it
is naturally in other areas of the creek. Maintaining normal depth of flow is also a
concern for us, so we ran a model with low discharges to verify that the normal water
depth would not be reduced too much by allowing the low flow through both culvert barrels.
Also a sill would have to be at least 3.5ft tall (2.Sft water depth + I.oft burial depth)
across one barrel to direct the flow into the other barrel.
I hope this has answered some of your questions. As I mentioned before i will be out of
the office on Monday but please call me on Tuesday if you have any other questions or
would like to discuss this further. If you need to speak with someone before then, you
can also speak with Jay Twisdalc, and lie should be in the cfLice on Monday.
Thanks,
Brook Anderson, PE
NCDOT Hydraulics Unit
1590 Mail Service Center
Raleigh, NC 27699
phone: [phone]
email: [e-mail]
Email correspondence to and from this sender is subject to the N.C. Public Records Law and
may be disclosed to third parties.
2