20011551 Ver 3_Other Agency Comments_20111201

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NCDENR
North Carolina Department of Environment and Natural
Division of Water Resources
Beverly Eaves Perdue
Governor
MEMORANDUM
FROM
�1:
Thomas A Reeder
Director
December 1 2011
�
Jim Mead SEPA Review Coordinator DWR �
Resources
Dee Freeman
Secretary
Monte Matthews Raleigh Regulatory Field Office US Army Corps of Engineers
SUBJECT NC Gramte Corporation Quarry Intake 404/401 Permit Application
Ararat River Surry County NC
SAW 2011 01765
The Division of Water Resources (DWR) has revtewed the U S Army Corps of Engineers application
notice for an after the fact intake and a proposed in stream diversion structure in the Ararat River to
provide process water for quarry activities DWR has the followmg comments
The quarry intake is located 4 nver miles upstream of Mt Airy s wastewater treatment plant
(WWTP) and the confluence with Lovills Creek The WWTP has a permitted discharge to the
Ararat River of 7 mgd Lovills Creek is a 303 d listed tributary of the Ararat River The Ararat
River is 303 d listed for turbidity in its lower 15 river mile reach to the Yadkin River
confluence This information ts presented for consideration of possible cumulative impacts
2 The notice states that the quarry presently requires 1 75 million gallon per day (mgd) or 2 7
cubic feet per second (cfs) to continue operation Is this value a daily average� What is the
maximum instantaneous withdrawal amount�
3 It is unclear from the drawings how the in stream structures will partrtion flow in the Ararat
River between the downstream flow by and the diversion into the quarry s reservoir
Information that would help clarify how the diversion and intake function includes
• The elevation of the lip of the quarry s bank side intake and the stream discharge
associated with that elevation
• The water surface elevation of the river at the 7Q10 flow
• The rating for the amount of water conveyed through the intake at different depths above
rts lip
• Water elevations should be provided for conditions with the instream rock vanes
installed It may be necessary to indicate these elevations at more than one location —
for example at the intake and for the flow by portion of the channel
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4 Based on preliminary DWR calculations the stated 2 7 cfs withdrawal slightly exceeds the
volume of water equivalent to 20%7Q 10 See below
USGS Stat�on #02113850 ARARAT RIVER AT ARARAT NC
Daily D�scharge 1964 04 Ol to 201 1 1 1 11
Dramage Area (DA) = 231 mi2
7Q 10 = 47 2 cfs ( 204 cfs/mi2)
Quarry Site Coordmates N36 50971 / W80 59201
DA — 65 mi2
7Q10 � 13 cfs
20%7Q 10 — 2 6 cfs (1 68 mgd)
DWR uses the 20% of 7Q10 value as a threshold to determine if further evaluation of the
impacts on instream flow and aquatic habitat is needed This evaluation could include a site
specific study to determine instream flow by requirements for operation of the intake It should
be noted that the maximum instantaneous wtthdrawal amount is used to calculate the percentage
of 7Q10 withdrawn If the 2 7 mgd withdrawal is an average daily value and the instantaneous
maximum withdrawal rate is higher then the 20% 7Q10 threshold would be more sigmficantly
exceeded
The applicant should provide information to help determine if a study to establish a flow by
requirement is required First they should contact the U S Geological Survey to obtain a
formal estimate of the 7Q10 at the withdrawal location The application should also include an
on site drought response plan and any water reuse/conservation efforts that would reduce the
withdrawal amount when flows in the Ararat River approach 7Q 10 drought levels
5 DWR s evaluation of instream flow concerns pertains to physical aquatic habitat Water quality
impacts are not part of this evaluation The appropnate DWQ staff should be consulted to
determme if reductions in the 7Q 10 flow at this upstream location at 65 square miles of
dramage area would adversely affect assimilative capacity at the Mt Airy WWTP located
farther downstream on the Ararat River
6 The applicant should provide a mamtenance plan to assure that the proposed installation and
intake will function as proposed over time
We recommend that the 404 permrt for this pro�ect be wrthheld until the addrtional information
described above has been provided by the applicant so that a review of mstream flow concerns can be
completed
Thank you for this opportumty to comment Please contact Fred Tarver at 919/715 5442 or
fred tarver(a�ncdenr � if you have any questions about these comments
cc Steve Reed Fred Tarver DWR
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