NC0055786_Permit Modification_19980713

State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
James B. Hunt, Jr., Governor
Wayne McDevitt, Secretary
A. Preston Howard, Jr., P.E., Director
July 13, 1998
Mr. R. Duke Whisenant
City of Lexington
22 West Center Street
Lexington, North Carolina 27292
rA
NCDENR
Subject: NPDES Permit Modification
City of Lexington WWTP
NPDES Permit No. NC0055786
Davidson County
Dear Mr. Whisenant:
The Division of Water Quality received your request for modification on June 20, 1998 for the above referenced
facility. The permit has been modified per your written request. The following list details changes made to fhb permit:
• The limits have been removed for mercury and lead.
• The monitoring frequencies for cadmium, lead, nickel, and mercury have been changed from weekly to twice per
month.
• The toxicity test language was updated to a more recent version, November 1995.
• The footnote pertaining to weekly monitoring of lead and mercury has been removed.
Please find enclosed an amended effluent sheet and footnote pages which should be inserted into your permit. The
old effluent pages and Part III, Conditions G. and H., should be discarded. All other terms and conditions contained in the
original permit remain unchanged and in full effect. This permit modification is issued pursuant to the requirements of
North Carolina General Statutes 143-215.1 and the Memorandum of Agreement between North Carolina and the U. S.
Environmental Protection Agency.
As a reminder, nutrient limits will be imposed and included in your permit at renewal. This was stated in the cover
letter at your last permit renewal, issued April 26, 1994. The proposed limits will be 0.5 mg/1 for Total Phosphorus and 4/8
mg/1 (summer/winter) for Total Nitrogen.
If any parts, measurement frequencies or sampling requirements contained in this permit modification 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, Post Office Drawer 27447, Raleigh, North
Carolina 27611-7447. Unless such a demand is made, this permit modification shall be final and binding. If you have any
questions, please contact Mary Cabe of my staff at [phone], extension 518.
Attachment
cc: Mooresville Regional Office, Water Quality Section
NPDES Unit
Central Files
Point Source Compliance Enforcement Unit
Pretreatment Unit
Mr. Roger Spach, City of Lexington
Sincerely,
A„,",
. r..1Preston Howard, Jr., P.
P.O. Box 29535, Raleigh, North Carolina 27626-0535 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 50% recycled/ 10% post -consumer paper

A. (1) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS - FINAL
Permit No. NC0055786
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from outfall serial number
001. Such discharges shall be limited and monitored by the Permittee as specified below:
;EFFLUENT CHARACTERISTICS
: 1 , , ;
• LIMITS
= MONITORING REQUIREMENTS
Monthly :
, Average
:,Weekly
Average ''.
Daily Maximum
Measurement
Frequency
Sample
Type "'
Sample
: Location1 R
Flow
5.5 MGD
Continuous
Recording
I or E
BOD, 5-day, 20°c (April 1 — October 31) 3
5.0 mg/L
7.5 mg/L
Daily
Composite
E, I
BOD, 5-day, 20°C (November 1— March 31) 3
10.0 mg/L
15.0 mg/L
Daily
Composite
E, I
Total Suspended Residue 3
30.0 mg/L
45.0 mg/L
Daily
Composite
E, I
NH3-N (April 1 — October 31)
2.0 mg/L
Daily
Composite
E
NH3-N (November 1 — March 31)
4.0 mg/L
Daily
Composite
E
Dissolved Oxygen 4
Daily
Grab
E
pHs
Daily
Grab
E
Total Residual Chlorine
Daily
Grab
E
Temperature, °C
Daily
Grab
E
Fecal Conform (geometric mean)
200 / 100 ml
400 / 100 ml
Daily
Grab
E
Total Nitrogen (NO2+NO3+TKN)
Monthly
Composite
E
Total Phosphorus
Monthly
Composite
E
Chronic Toxicity 6
Quarterly
Composite
E
Mercury
2/Month
Composite
E
Cadmium
2/Month
Composite
E
Chromium
Monthly
Composite
E
Nickel
2/Month
Composite
E
Lead
2/Month
Composite
E
Cyanide
Quarterly
Grab
E
Zinc
•
Monthly
Composite
E
' Silver
Quarterly
Composite
E
Copper
Monthly
Composite
E
Dissolved Oxygen
2
2
2
Temperature, °C
2
2
2
Fecal Conform (geometric mean)2
2
Conductivity
2
2
2
Total Phosphorus
2
2
2
TKN
2
2
2
NO2+NO3
2
2
2
Chlorophyll -a
2
2
2
NH3 as N
2
2
2
Notes:
See the following Supplement to Effluent Limitations pages for footnotes.