20011551 Ver 4_Other Agency Comments_20120606

Regulatory Division/1145
DEPARTMENT OF THE ARMY
WILMINGTON DISTRICT, CORPS OF ENGINEERS
69 DARLINGTON AVENUE
WILMINGTON, NORTH CAROLINA 28403 -1343
Action ID: SAW- 2011 -01765
NC Granite Corporation
Mr. Kenny Moles
151 Granite Quarry Trail
Mount Airy, North Carolina 27030
Dear Mr. Moles:
June 4, 2012
o 1- 1 SSl Y4
Reference the letter from your authorized agent, Mr. Michael Wood of The Catena Group,
dated March 30, 2012, responding to comments received by our Public Notice on your proposed
project within the Ararat River at the North Carolina Granite Corporation in Mount Airy, Surry
County, North Carolina. Also reference the follow -up email dated May 15, 2012, containing the
No- Rise/No- Impact Certification from the local FEMA Floodplain Administrator.
After reviewing this information, we have determined that additional details are needed prior
to a permitting decision. Regarding the information provided in response to questions from the
North Carolina Division of Water Resources, the following items need clarification:
1) The lip ( "invert") of the w -weir and the intake are both set at an elevation of
1013.5'. The 7Q10 is estimated to occur at 1013.8'. However, the document also states
"...the invert of the intake is set at 20.7% of the low flow (7Q 10), which provides a
physical impediment to water withdrawal." 20.7% equates to 2.69 cfs. Does this imply
that there will be a lip in front of the intake set at an unspecified elevation between
1013.5 and 1013.8 ft to allow 2.69 cfs to pass?
2) A Stage - Discharge Rating Table is provided and the table header states the
elevation to be above the invert but doesn't say which invert, the intake or the w -weir. It
was initially thought that it is the intake because at the estimated 7Q 10 flow of 13 cfs the
elevation is 0.333, versus 0.3. However, the 20.7% invert that equates to 2.69 cfs is not
evident because the table shows that at a depth of 0.05' the total flow is 0.4 cfs with a
withdrawal of 0.1 cfs. Also, the withdrawals don't cap at 20% but continue to 19.2 cfs at
1', which equates to 147% of the 7Q 10. Please provide further clarification. In addition,
please confirm that the proposed withdrawal system does not have the capacity to
withdraw greater than a volume equivalent to 20% of the estimated
Printed on Recycled Paper

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3) It is unclear if this is a passive or pumping intake. If passive, what is the
maximum instantaneous withdrawal capacity of the conduit at the top elevation of the
conduit? If pumping, please provide the maximum instantaneous withdrawal, as opposed
to the maximum daily of the pumps.
4) Please clarify the Stage - Discharge Rating Table regarding the potential for the
sum of `Qweir' and `Qintake' to equal `Qtotal'? Additional information is needed if you
have accounted for supplementary figures within `Qtotal', and not disclosed them within the
Table.
In addition, a few comments /questions were raised from US Army Corps of Engineer staff
concerning this proposal and the downstream Renfro Levee. Please reference the "Hydraulic
Analysis Report No- Impact Certification, Ararat River Project at NC Granite Facility" and supply
additional information as requested:
1) It appears that the newly proposed project will have very little impact on the level
of protection needed for FEMA's no -rise certification for the 100 -yr base flood condition.
2) It would be very useful to have each of the water surface elevations plotted in the
HEC -RAS cross sections of the report, including pre - project water surfaces.
3) It appears that although these water surfaces are useful for determining if the
newly proposed project will be acceptable for no -rise certification for 100 -yr Base Flood,
there is no indication in this report that the Base Flow, which could be best described as
"every -day normal flow" and it's associated water surface elevation at the Renfro site would
be impacted by this newly proposed structure, thereby affecting the operability of the flap
gates and interior drainage. One of the main reasons the former project (dam) was causing
problems in the beginning was that there was water up against the flap gates at the Renfro
site during Base Flow conditions (again, not to be confused with Base Flood conditions)
because of the backwater caused by the dam. In flood conditions, the new project is
completely submerged and so has little impact on the resultant 100 -year water surface
elevation. Please supply additional information to help with this determination.
On May 31, 2012, Mr. Monte Matthews and Mr. Wood met on site to discuss additional
avoidance and minimization measures for the Ararat River side channel. In particular, these
measures would explore methods for supplying adequate base and storm flow hydrology to the side
channel to support typical stream functions. Adequate flow, as demonstrated during a monitoring
period, would lessen anticipated changes in stream functions, minimize and/or avoid impacts, and
help defer the need for compensatory mitigation. However, the site visit found the side channel

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hydrology not sufficient to preclude the need for an additional analysis on additional avoidance and
minimization, as required prior to a permitting decision. Depending on the information you
provide, compensatory mitigation may still be required unless the hydrology can be augmented.
Your response to these comments must be given full consideration before we can make a final
decision on your application. We need your information to address the concerns /issues raised over
the proposed project. You may submit additional information, revise your plans to help resolve the
issues, rebut the issues made, or request a decision based on the existing record. Once we have
determined that all comments have been adequately addressed, we will re -open our assessment of
your project.
If you have questions or comments, please contact Monte Matthews at the Raleigh Regulatory
Field Office address, telephone [phone] ext. 30.
Sincerely,
Copy Furnished:
Mr. Ian McMillan
NCDWQ
1650 Mail Service Center
Raleigh, NC 27699 -1650
Ms. Amy Euliss
NC DENR Winston -Salem Regional Office
DWQ
585 Waughtown Street
Winston - Salem, NC 27107
Mr. Michael Wood
The Catena Group
410B Millstone Drive
Hillsborough, NC 27278
Jean B. Gibby
Chief, Raleigh Regulatory
Field Office