NC0069841_denial_20080507

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May 7, 2008
Ms. Christine Putnam
Union County Public Works
400 North Church Street
Monroe, North Carolina 28112-4730
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Coleen H. Sullins, Director
Division -of Water Quality
Subject: Speculative Effluent Limits
Crooked Creek WWTP
NPDES Permit No. NCO069841
Union County
Dear Ms. Putnam:
This letter is offered in response to Hazen & Sawyer's request, on Union County's behalf, for speculative effluent
limits for the potential expansion of the Crooked Creek Wastewater Treatment Plant (WWTP). The plant is
currently permitted for a wastewater discharge of up to 1.9 MGD into North Fork Crooked Creek, located in the
Yadkin Pee Dee River Basin. The letter requested an expansion on North Fork Crooked Creek or an expansion
and relocation to South Fork Crooked Creek.
The South Fork Crooked Creek has zero 7Q10 and 30Q2 flows. Based on 15A NC AC 2B. 0206(d)(2), no new or
expanded discharges of oxygen consuming can be allowed. Therefore, the Division cannot provide speculative
limits for this location.
The North Fork Crooked Creek has zero summer 7Q10 and 0.23 cfs 30Q2 (confirmed by USGS on March 18,
2008). At both upstream and downstream locations of the discharge, Coalition monitoring data indicate dissolved
oxygen (DO) values less than the North Carolina water quality standard of 5 mg/L ( with generally lower DO's
occurring downstream of the discharge). Even under these conditions, the Division performed a water quality
model for the requested expansion. As with the Twelve Mile Creek request, the model was determined to be an
inappropriate tool for the existing stream conditions (and not reflective of actual conditions). Therefore, the
Division cannot provide speculative limits at the North Fork Crooked Creek location, based on both of the reasons
stated previously.
As has been discussed previously with the County, any and all alternatives to discharge should be explored due to
the limited stream flow and low dissolved oxygen levels in that portion of the Union County.
If you would like to meet and discuss these issues, please contact me at [phone] ext. 510.
;Sincer ly,
san A. Wilson, P.E.
Supervisor, Western NPDES Program
cc: DWQ Mooresville Regional Office/Surface Water Protection Section
Central Files .
NPDES Permit File
Hazen & Sawyer, P.C./James N. Struve, P.E.
4944 Parkway Plaza Blvd. Ste # 375 One
tttCarolina
Charlotte, NC 28217 )WA MIdy
North Carolina Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 Phone [phone] Customer Service
Internet: www.ncwaterauality. ora Location: 512 N. Salisbury St. Raleigh, NC 27604 Fax [phone]
An Equal Opportunity/Affirmative Action Employer-50% Recycled/10% Post Consumer Paper

Low -flow characteristics for North Fork Crooked Creek ... Re: Stream Flow Data for North... Page 1 of 2
From: John C Weaver [e-mail]]
Date: Mar 18, 2008 13:10
To: "Agyeman Adu-Poku"<[e-mail]>
Cc. "John C Weaver'<[e-mail]>
Subject: Low -flow characteristics for North Fork Crooked Creek ... Re: Stream Flow Data
for North Fork Crooked Creek
Agyeman,
In response to your inquiry about the low -flow characteristics for a location on North Fork Crooked Creek in
western Union County, the following information is provided:
A check of the low -flow files here at the USGS North Carolina Water Science Center office indicates a
previous determination of low -flow characteristics for a location immediately upstream of your point of
interest (lat/long 350547 / 803553) as well as some other nearby locations on North Fork Crooked Creek.
The previous estimates for the upstream location were determined in January 1994 (station id 0212474492,
drainage area 13.4 sgmi) based on the flow characteristics at a downstream USGS partial -record site on
North Fork Crooked Creek (station id 0212475, drainage area 16 sgmi). In the absence of site -specific data
for low -flow analyses, estimates of the 7Q10 discharge are determined by assessing the range of low -flow
yields (expressed as flow per square mile drainage area, or cfsm) at nearby locations where the 7Q10 has
been previously determined.
The most recent low -flow information published for most streams in Union County is in a basinwide low -flow
report completed in 2003. It is USGS Water -Resources Investigations Report 03-4147, "Low -Flow
Characteristics and Profiles for the Rocky River in the Yadkin -Pee Dee River Basin, North Carolina, through
2002" (Weaver and Fine, 2003). An online version of the report is available through
http://pubs.usgs.gov/wri/wri034147/. The report provides the low -flow characteristics (based on data through
2002) for continuous -record gaging stations and partial -record sites within the Rocky River basin. The report
also provides low -flow discharge profiles (7Q10, 30Q2, winter 7Q10, and 7Q2) for the Rocky River from its
headwaters in Mecklenburg County to its mouth.
Several pieces of information to consider:
(1) In Table 6 of the Rocky River low -flow report, the low -flow characteristics for the downstream partial -
record site on North Fork Crooked Creek were published:
7Q10=0cfs
30Q2 = 0.5 cfs (equivalent to 0.0313 cfsm)
W7Q10 = 0.2 cfs (equivalent to 0.0125 cfsm)
Qavg = 1.0 cfsm
(2) While the 7Q10 estimate has not changed, the above yields for the downstream partial -record site are
about 2 times higher than those used during the 1994 estimate.
(3) Applying the drainage area for upstream site (station id 0212474492, drainage area 13.4 sgmi) to the
above yields will result in following flow estimates that can be used for your point of interest:
7Q10=0cfs
30Q2 = approximately 0.4 cfs
W7Q10 = approximately 0.2 cfs
Qavg = approximately 13 cfs
Hope this information is helpful.
Thank you.
Curtis Weaver
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Low -flow characteristics for North Fork Crooked Creek ... Re: Stream Flow Data for North... Page 2 of 2
m
J. Curtis Weaver, Hydrologist, PE
USGS North Carolina Water Science Center
3916 Sunset Ridge Road
Raleigh, NC 27607
Telephone: [phone] H Fax: [phone]
E-mail address -- [e-mail]
Internet address -- http://nc.water.usgs.gov/
Agyeman Adu-Poku To John C Weaver <[e-mail]>
<[e-mail]>
cc
03/12/2008 02:24 PM Subject Stream Flow Data for North Fork Crooked Creek
Curtis.
Would you happen to have current stream flow data on North Fork Crooked
Creek? The lat/long, is 35 05 47/80 35 53.
I am not sure of the drainage area so I am looking for 7Q10 (summer and
winter), 30Q2 and Qavg.
Thanks for your help.
Agyeman
[attachment "Agyeman.Adupoku.vcf" deleted by Sohn C Weaver/WRD/USGS/DOI]
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Stream FIow Data for North Fork Crooked Creek
Subject: Stream Flow Data for North Fork Crooked Creek
From: Agyeman Adu-Poku <[e-mail]>
Date: Wed, 12 Mar 2008 14:24:04 -0400
To: John C Weaver <[e-mail]>
Curtis,
Would you happen to have current stream flow data on North Fork Crooked Creek? The
lat/long is 35 05 47/80 35 53.
I am not sure of the drainage area so I am looking for 7Q10 (summer and winter), 30Q2
and Qavg.
Thanks for your help.
Agyeman
Agyeman Adu-Poku <agyeman.adupoku cz;ncmail.net>
Environmental Engineer
Department of Environment & Natural Resources
Division of Water Quality-NPDES Unit
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1 of 1 3/12/2008 2:25 PM