NC0036269_Permit Modification_20100702

North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coieen H. Sullins
Governor Director Dee Freeman
Secretary
July 2, 2010
Mr. Evaiider Rowell, P.E.
Engineering Director
WSACC
P.O. Box 428
Concord, NC 28026-0428
Subject: Perinit Modification #2 for Interim Flow
NPDES Permit NC0036269
WSACC Rocky River WWTP
Cabarrus County
Dear Mr. Rowell:
Division staff previously approved your modification request for an interim flow effluent sheet for 26.5 MGD, in
addition to the existing phased effluent sheets for 24 MGD and 34 MGD. That modification, dated March 16, 2010, stated
that in order to activate the 26.5 MGD interim flow, the facility must receive approval from DWQ Construction Grants and
Loans for a facility rerate to this interim flow. If this rerate is not approved, the facility will remain at 24 MGD with
approved future expansion to 34 MGD upon receipt of Authorization to Construct/Engineer's Certification.
Per your request, attached please find modified effluent sheets for 24 MGD and 26.5 MGD, that further detail the transition
from 24 MGD to 26.5 MGD, based on DWQ approval of the rerate, as well as the facility reaching 90% of permitted flow
(or 21.6 MGD on a maximum month basis). The facility is required to notify the Division when this transition occurs.
This permit modification is issued pursuant to the requirements of North Carolina General Statute 143-215.1 and the
Memorandum of Agreement between North Carolina and the U.S. Environmental Protection Agency dated October 15,
2007 (or as subsequently amended). If any parts, measurement frequencies or sampling requirements contained in this
permit are unacceptable to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days
following receipt of this letter. This request must be in the form of a written petition, conforming to Chapter 150B of the
North Carolina General Statutes, and filed with the Office of Administrative Hearings (6714 Mail Service Center,
Raleigh, North Carolina 27699-6714). Unless such demand is made, this decision shall be final and binding.
Please note that this permit is not transferable except after notice to the Division. The Division may require modification
or revocation and reissuance of the pelniit. This permit does not affect the legal requirements to obtain other permits
which may be required by the Division of Water Quality or permits required by the Division of Land Resources, the
Coastal Area Management Act or any other Federal or Local governmental permit that may be required.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617
Location: 512 N. Salisbury St. Raleigh, North Carolina 27604
Phone: [phone] t FAX: [phone]. k Customer Service: J-877-623-6748
Internet: www.ncwaterquafity.org
An Equal Opportunity `. Affirmative Action Employer
One
NorthCarolina
Naturally

4.
If you have any questions on this permit modification, please contact me at 919-807-6390.
Cc: NPDES Permit File
Central Files
MRO, Surface Water Protection
Ecopy: Construction Grants & Loans, Seth Robertson
US EPA, Marshall Hyatt
1617 Mail Service Center, Raleigh, North Carolina 27699-1617
Location: 512 N. Salisbury St. Raleigh, North Carolina 27604
Phone: [phone] FAX; 919-807-6492 \ Customer Service: 1-877-623-6748
Internet: www.ncwaterquality.org
An Equal Opportunity Affirmative Action Employer
Supervisor, NPDES Complex Permitting
NorthCarolina
Naturally

Permit NC0036269
A. (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [24.0 MGD]
During the period beginning on November 1, 2008 and lasting until flow reaches 90% of permitted flow (Le., 21.6 MGD on
a maximum month basis) or permit expiration, the Permittee is authorized to discharge from Outfall 001. Such discharges
shall be limited and monitored by the Permittee as specified below:
PARAMETER ;'
_ v LIMITS :;
MONITORING RE.QUIREMENTSr- ,
Monthly s
Average';; -
Weekly
;Average ._',
b Daily
Average
Measurement
-, !Frequency
" Sample
" Type
Sample
Location' --
Flow -
24.0 MGD
Continuous
Recording
, Influent or
Effluent
CBOD, 5.day, 20°C Summer
(April 1 - October 31)2
17.0 mg/L
25.5 mg/L
Daily
Composite
Influent &
Effluent
CBOD, 5 day, 20°C Winter
(November 1 - March 31) 2
25.0 mg/L
37.5 mg/L
Daily
Composite
Influent &
Effluent
Total Suspended Solids (TSS) 2
30.0 mg/L
45.0 mg/L
Daily
Composite
Influent &
Effluent
NH3 as N Summer
(April 1— October 31)
4.0 mg/L
12.0 mg/L
Daily
Composite
Effluent
NH3 as N Winter
(November 1 - March 31)
10.0 mg/L
30.0 mg/L
Daily
Composite
Effluent
Dissolved Oxygen
Daily average > 6.0 mg/L
Daily
Grab
Effluent -
Total Residual Chlorine3
28 pg/L
Daily
Grab
Effluent
Fecal Coliform
(geometric mean)
200 / 100 mL
400 / 100 mL
Daily
Grab
, Effluent
Total Nitrogen
(NO2 + NO3 + TKN)
Monthly
Composite
Effluent
Total. Phosphorus
Monthly
Composite
Effluent
Chronic Toxicity4
Quarterly
Composite
Effluent
Temperature, °C
Daily
Grab
Effluent
pH
> 6.0 and < 9.0 standard units
Daily
Grab
Effluent
Temperature, °C5
Variable 6
Grab
U, D
Conductivity5
Variable 6
Grab
U, D
Dissolved Oxygen5
Variable 6
Grab.
U, D
Fecal Coliform
(geometric mean) 5
Variable 6
Grab
,
U, D
Table Footnotes:
1. U: Upstream at NCSR 1132; Di: Downstream at U.S. Highway 601; D2: Downstream at NCSR 1006.
2. Monthly average effluent values for Carbonaceous Biochemical Oxygen Demand (CBOD5) and TSS shall not exceed
15% of the respective influent values (i.e. 85% removal).
3. Total Residual Chlorine (TRC). The facility shall report all effluent TRC values reported by a NC certified laboratory
including field certified. However, effluent values below'50 ug/L will be treated as zero for compliance purposes.
4. Chronic Toxicity (Ceriodaphnia) at 59.6%: sample quarterly during February, May, August, and November [see A.
(4)].
5. Monitoring upstream (U) and downstream (DI and D2) are provisionally waived; based on membership in the Yadkin
— Pee Dee River Basin Association. If at any time during the term of this permit, membership is terminated, the
Permittee shall notify the Division immediately, and immediately conduct instream monitoring as stipulated in this
permit.
6. Variable Frequency — The Permittee shall collect instream samples three times per week (3/week) during the months
of June, July, August, and September; and once per week (1/ week) during April, May, and October only.
Effluent shall contain no floating solids or foam visible in other than trace amounts.

Permit NC0036269
A. (2) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS [26.5 MGD]
During the period beginning with flow > 21.6 MGD on a maximum month basis (and with DWQ Rerate Approval to 26.5
MGD) and,tasting until permit expiration or expansion to 34 MGD, the Permittee is authorized to discharge from Outfall
001. Suck' discharges shall be limited and monitored by the Permittee as specified below:
PARAMETER x„ , _ •
_• ... ; LIMITS. . .. :
MONITORING; REQUIREMENTS
.
Morithly
Ave_rage
eeklY
=Average
aiY
Average ,
Measurement
Frequency
`Sam le
Type,:.
;Simple e
ocation
Flow
26.5 MGD '
Continuous
Recording,
Influent or
Effluent
CBOD, 5 day, 20°C Summer
(April 1 - October 31)2
15.4 mg/L
23.1 mg/L
Daily
Composite
Influent &
Effluent
CBOD, 5 day, 20°C Winter
(November 1 - March 31) 2`
22.6 mg/L
33.9 mg/L
Daily
Composite
Influent &
Effluent
Total, Suspended Solids (TSS) 2
30.0 mg/L
45.0 mg/L
Daily
Composite •
Influent &
Effluent
NH3 as N Summer
(April 1 — October 31)
3.6 mg/L
10.8 mg/L
Daily
Composite
Effluent
NH3 as N Winter
(November .1 - March 31)
9.0 mg/L
27.0 mg/L
Daily
Composite
Effluent
Dissolved Oxygen
Daily average > 6.0 mg/L
Daily ..
Grab
Effluent
Total Residual Chlorine3
27 pg/L
Daily
Grab
Effluent
Fecal Coliform
(geometric mean)
200 / 100 mL
400 / 100 mL
Daily
Grab
Effluent
Total Nitrogen
(NO2 + NO3 + TKN)
Monthly
Composite
Effluent
Total Phosphorus
Monthly
Composite
Effluent
Chronic Toxicity4
Quarterly
Composite '
Effluent
Temperature, °C
Daily
Grab
Effluent
pH
> 6.0 and < 9.0 standard units
' Daily
Grab
Effluent
Temperature, °C5
Variable 6
Grab
U, D
Conductivity5
Variable 6
Grab
U, D
Dissolved Oxygen5
Variable 6
Grab
U, D
Fecal Coliform
(geometric mean) 5
Variable 6
Grab
U, D
Table Footnotes:
1. U: Upstream at NCSR 1132; D,: Downstream at U.S. Highway 601; D2: Downstream at NCSR 1006.
2. Monthly average effluent values for Carbonaceous Biochemical Oxygen Demand (CBOD5) and TSS shall not exceed
15% of the respective influent values (i.e. 85% removal).
3. Total Residual Chlorine (TRC). The facility shall report all effluent TRC values reported by a NC certified laboratory
including field certified. However, effluent values below 50 ug/L will be treated as zero for compliance purposes
4. Chronic Toxicity (Ceriodaphnia) at 62.0%: sample quarterly during February, May, August, and November [see A.
(4)].
5. Monitoring upstream (U) and downstream (DI and D2) are provisionally waived, based on membership in the Yadkin
— Pee Dee River Basin Association. If at any time during the term of this permit, membership is terminated, the
Permittee shall notify the. Division immediately, and immediately conduct instream monitoring as stipulated in this
permit.
6. Variable Frequency — The Permittee shall collect instream samples three times per week (3/week) during the summer
months of June, July, August, and September; and once per week (1/ week) during the months of April, May, and
October only.
Effluent shall contain no floating solids or foam visible in other than trace amounts.

t
• WSACC
WATER & SEWER AUTHORITY
OF CABARRUS COUNTY
June 4, 2010
Mr. Tom Belnick
Supervisor, NPDES Point Source Branch
Division of Water Quality
1617 Mail Service Center
Raleigh, North Carolina 28001
gg[ig-Mg:
JUN-92010
DENR - wi rER QLl,,LJ , Y
Wetlands & %a m titer gran
Office: 232 Davidson Hwy.
Concord, NC 28027
Mail to: P.O. Box 428
Concord, NC 28026-0428
Phone: [phone]
Fax: [phone]
SUBJECT: "Effluent Limitations" for 26.5 mgd Plant Re -rating - Water & Sewer Authority
of Cabarrus County (WSACC) - NPDES Permit No. NC 0036269
Dear Mr. Belnick:
I am writing this letter in reference to recent discussions with you concerning the implementation
of the "effluent limitations" that were established for a re -rating of our Rocky River Regional
WWTP from 24.0 mgd to 26.5 mgd as outlined in your letter of 3/16/10.
Our review of the 26.5 mgd effluent limitations information that was provided indicated that
these limitations would become effective upon formal approval by DWQ Construction Grants
and Loans of the re -rating report/technical documentation. Although not provided for, it was our
understanding that the 26.5 mgd effluent limitations would be phased in, and the current 24.0
mgd effluent limitations would remain effective for a given period of time based on the current
permitted flow of 24.0 mgd. You stated that this would need to be requested, but felt that this
could be drafted into the modified permit.
Therefore, it is requested that the 26.5 mgd effluent limitations become effective when the plant
effluent flow equals 21.6 mgd on a maximum month basis, which represents 90% of the current
24.0 mgd permitted flow.
If you need any additional information relative to this request, please let me know. Your help
and assistance in regard this re -rating effort is greatly appreciated.
Sincerely,
Evander H. Rowell, P.E.
Engineering Director
EHR:jss
cc: Ray Furr
Jim Struve — Hazen & Sawyer
Mike Parker — DWQ/Mooresville