NC0024945_Correspondence_19910212

NPDES DOC /WENT SCANNING COVER SHEET
NPDES Permit:
NC0024945
Irwin Creek WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
Draft Permit
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
February 12, 1991
This document is printed on reuse paper. - ignore any
content on the reYerse side

State of North Carolina
Department of Environment, Health and, Natural Resources
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Governor George T. Everett, Ph.D.
William W. Cobey, Jr., Secretary Director
February 12, 1991
Mr. Joe Stowe
Charlotte - Mecklenburg Utility Department
5100 Brookshire Boulevard
Charlotte, North Carolina 28216
Subject: NPDES Permit Adjudications
NC0024970 - McAlpine Creek
NC0024945 - Irwin Creek
NC0024937 - Sugar Creek
Mecklenburg County
Dear Mr. Stowe:
In accordance with our discussions on February 8, 1991, this correspondence is to sum
up the current position of the Water Quality Section relative to the three NPDES Permits which
became effective July 1, 1990.
In light of the permits' expiration date of August 31, 1991, I believe the best approach is
to proceed with renewal and expansion of the subject permits at the same time. It is our intention to
resolve the adjudications during this process. Although the adjudicatory issues are numerous, I see
the following as productive measures to reduce all differences:
McAlpine Creek
1) DEM agrees to a schedule for metals (cadmium, chromium, nickel, lead, and cyanide)
with monitoring only from the date of issuance until December 31, 1991. Effective
January 1, 1992, and lasting until the expiration of the permit, the effluent limitations
for the heavy metals will be applicable. Such metals will be limited as weekly average
and daily maximum as specified in the NPDES permit issued June 8, 1990.
2) DEM agrees to increased flow to 48.0 MGD upon upgrade to meet 4.0 mg/1 CBOD5,
1.0 mg/1 Ammonia (NH3 as N), 15.0 mg/1 Total Suspended Solids and other limits as
appropriate to become effective May 1, 1994.
3) Toxicity limitations will remain as issued yet DEM agrees to modify at permittee's
request based upon modifications approved by the Director as per the Ad -Hoc
Committee recommendations.
Pollution Prevention Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer
41010

Page 2
Mr. Joe Stowe
Charlotte - Mecklenburg Utility Department
Sugar Creek
1) DEM agrees to a schedule for metals (cadmium, chromium, nickel, lead, and cyanide)
with monitoring only from the date of issuance until December 31, 1991. Effective
January 1, 1992, and lasting until the expiration of the permit, the following effluent
limitations for the heavy metals will be applicable:
Weekly Avg Daily Max
Parameter (ug/1 (ug/1)
Cadmium 2.3 5.7
Nickel 101 404
Lead 29 39
Cyanide 5.7 19
Mercury 0.014 0.056
2) DEM agrees to increased flow to 19.67 MGD upon upgrade to meet 5.0 mg/1 CBOD5,
1.0 mg/1 Ammonia (NH3 as N), 15.0 mg/1 Total Suspended Solids and other limits as
appropriate to become effective April 1, 1995.
3) Toxicity limitations will remain as issued yet DEM agrees to modify at permittee's
request based upon modifications approved by the Director as per the Ad -Hoc
Committee recommendations.
Irwin Creek
1) DEM agrees to a schedule for metals (cadmium, chromium, nickel, lead, and cyanide)
with monitoring only from the date of issuance until December 31, 1991. Effective
January 1, 1992, and lasting until the expiration of the permit, the following effluent
limitations for the heavy metals will be applicable:
Weekly Avg Daily Max
Parameter (ug/1 (ug/1)
Cadmium 2.4 6.1
Nickel 107 428
Lead 30 41
Cyanide 6.1 21
Chromium 61 224
2) DEM agrees to increased flows for McAlpine Creek and Sugar Creek upon upgrade of
the Irwin facility to meet 5.0 mg/1 CBOD5, 1.0 mg/1 Ammonia (NH3 as N), 15.0 mg/1
Total Suspended Solids and other limits as appropriate to become effective April 1,
1995.
3) Toxicity limitations will remain as issued yet DEM agrees to modify at permittee's
request based upon modifications approved by the Director as per the Ad -Hoc
Committee recommendations.
As stated earlier and as you are well aware, the three permits expire on August 31, 1991.
To comply with the requirement to submit each of the renewal requests 180 days prior to expiration

Page 3
Mr. Joe Stowe
Charlotte - Mecklenburg Utility Department
we will need to have the requests for expansion and renewal no later than March 1, 1991. We
anticipate being able to draft the expansion and renewal permits no later than April 1, 1991 and
provide you a copy at this time. Hopefully, any comments you may have on the subject permits
may be resolved and the pending permit adjudication petitions withdrawn on or before April 15,
1991. We anticipate the Public Notice of the permits on or about April 15, 1991, and if no
significant adverse public comment is received, the permits should be issued approximately June 1,
1991.
Please review this information as soon as practical and contact me at [phone] at your
earliest convenience.
cc: Mooresville Regional Office
Permits and Engineering Unit
Technical Support Branch
Sincerely,
Steve W. Tedder, Chief
Water Quality Section
eb

DIVISION OF ENVIRONMENTAL MANAGEMENT
February 11, 1991
MEMORANDUM
TO: Steve Tedder
THROUGH: Trevor Clement
FROM: Ruth Swanek iS
SUBJECT: Charlotte's toxics limits for proposed expansions
The following toxics limits for the City of Charlotte's
proposed WWTP expansions are provided for your use in working with
the City:
McAlpine Creek WWTP (for proposed 48 MGD)
Weekly Avg. Daily Max.
Cadmium (ug/1) : 2.0 5.1
Chromium (ug/l): 51 204
Nickel (ug/1) : 90 360
Lead (ug/1) : 25 35
Cyanide (ug/1) : 5.1 16
T.R. Chlorine (ug/1) : 17
IWC: 98%
In addition, effluent monitoring for copper, zinc, and silver
should be performed weekly, and the spreadsheet (Attachment 1)
indicates that each metal should be monitored instream.
Sugar Creek WWTP (for proposed 19.67 MGD WWTP)
Weekly Avg. Daily Max.
Cadmium (ug/1) : 2.2 5.6
Nickel (ug/1) : 98 392
Lead (ug/1) : 28 38
Cyanide (ug/l) : 5.6 18
Mercury (ug/1) : 0.013 0.052
T.R. Chlorine (ug/ 1) : 19
IWC: 90%
In addition, weekly effluent monitoring should be performed
for chromium, copper, zinc, and silver (Attachment 2). The
observed data indicated that an effluent limit could have been
assigned for chromium, but the data used in this analysis were sub-
mitted by Charlotte although not required in the NPDES permit.
Therefore, no limit was assigned. The spreadsheet also indicated

that the City should monitor for cadmium, copper, lead, and zinc
instream (recommended in last WLA as well).
Irwin Creek WWTP (existing 15 MGD WWTP)
The chlorine limit for the Irwin Creek WWTP was calculated as
20 ug/1 (IWC = 83%) .
If you have any questions or comments, please do not hesitate
to contact me.
Attachments
cc: Rex Gleason
Dale Overcash