NC0023884_Staff Comments_19940907

DIVISION OF ENVIRONMENTAL MANAGEMENT
Water Quality Section/Instream Assessment Unit
MEMORANDUM
TO:
FROM:
Jay Lucas
Betsy Johnson
September 7, 1994
THROUGH: Steve Bevington --`)0
Ruth Swanek -L)
SUBJECT: Salisbury - Grants Creek WWTP draft permit
Grants Creek WWTP
NPDES No. NC0023884
Rowan County
I have reviewed the comments provided by the City of Salisbury regarding the draft permit for the
Grants Creek WWTP.
Comment #2 regarding the permit limits for cadmium, cyanide, and mercury indicates the City
cannot meet these limits. The limits are required to protect water quality since the facility has
had violations in the past. The limits are based on current SOP and review by pretreatment.
There are two remaining issues:
a. Allowing monitoring only until relocation - if this is permitted, effluent cadmium, cyanide,
and mercury levels should be monitored weekly. Instream monitoring of cadmium, cyanide,
and mercury should be conducted monthly 100 feet above and below the discharge.
b. Change our standards - I cannot address this issue; Planning is currently working on the
triennial review of NC's standards with EPA and the issues Salisbury has listed are being
discussed. Greg Thorpe may wish to comment on Salisbury's questions.
Comment #3 indicates weekly instream monitoring is required during the winter months at site 3.
This may be reduced to summer months (June - Sept.) at site 3.
If you have questions regarding these comments, please let me know.
cc: Carla Sanderson
Greg Thorpe
Mooresville Regional Office

July 14, 1994
Mr. David A. Goodrich
Department of Environment, Health & Natural Resources
Division of Environmental Management
NPDES Permit Group
Post Office Box 29535
Raleigh, North Carolina 27626-0535
Subject: Salisbury - Grants Creek Wastewater Treatment Plant
NPDES Permit No. NC0023884
Dear Mr. Goodrich:
The City of Salisbury (the "City") is in receipt of draft NPDES permit No. NC0023884 (the "draft
permit") prepared by the Division of Environmental Management ("DEM") for the City's
wastewater treatment facility at Grants Creek (the "facility"). The City appreciates the
opportunity to comment on this draft before a final permit is issued. We have set forth our
comments and concerns below.
1. The facility description on the Supplement to Permit Cover Sheet incorrectly states
that preliminary treatment consists of "a bar screen and grit removal;" it should state that
preliminary treatment consists of "4 bar screens and grit chambers." The facility is further
described as consisting of "three secondary clarifiers with polymer addition." Polymer
addition is not a permanent part of the treatment process and, therefore, this clause should
be deleted from the description of the facility.
2. The City's monitoring results over the last several years indicate that the City
cannot consistently meet the draft permit limits for cadmium, cyanide, and mercury. As
the DEM is aware, the City has undertaken substantial measures to upgrade its facility.
Even with these upgrades, however, the facility does not have the capability to
consistently meet these limits. Given the inordinately low flow of Grants Creek, the
theoretical worse case calculation of these limits is impossible to consistently meet.
CITY OF SALISBURY
P.O. BOX 479, SALISBURY, NORTH CAROLINA 28145-0479

Mr. David A. Goodrich
July 14, 1994
Page 2
During numerous discussions between the City and DEM, it has been determined that the a
long-term solution to this problem is for the City to build a discharge directly to the
Yadkin River. The City, therefore, has begun the process of constructing an effluent
pipeline from its Grants Creek and Town Creek wastewater treatment plants to the
Yadkin River. This project has begun and will be completed within three years. Until the::
City reaches the Yadkin, we request that the effluent limits for cadmium, mercury and
cyanide be replaced by a monitoring requirement.
,Further, the City believes these limits are unacceptable because they were wrongly
derived. Our understanding is that the limits for cadmium and mercury were calculated as
follows: (Maximum in -stream concentration) x (dilution factor). Pursuant to 15A NCAC
2B.0211(b)(3)(L) the maximum in -stream concentration for cadmium is 0.4 ug/1 for trout
waters and 2.0 for non -trout waters and for mercury is .012ug/1 Our research indicates
that these in -stream concentrations are unreasonably stringent. The State adopted these
values based upon EPA guidance published in 1985, Ambient Water Quality Criteria for
Cadmium - 1984, USEPA, Office of Water, Jan. 1985, Ambient Water Quality Criteria
for Mercury-1984. USEPA, Office of Water, Jan. 1985. EPA, however, subsequently
determined that these criteria are too stringent and has revised its position on the
derivation of the water quality criteria for cadmium and mercury. See Interim Guidance
on Interpretation and Implementation of Aquatic Life Criteria for Metals, USEPA, Office
of Science & Technology, May, 1992, and Guidance Document on Dynamic Modeling
and Translators, August, 1993, USEPA, Office of Water Policy, and the Memorandum
entitled Technical Guidance on Interpretation and Implementation of Aquatic Life Metals
Criteria, USEPA, Office of Water, October 1, 1993, (hereinafter "memorandum"). The
EPA is currently developing new criteria; until these new criterion are derived, EPA
recommends that State water quality standards be based on the dissolved portion of the
metal or that States accept site specific criteria. See Memorandum p.3 and p.5. Limits
in the draft permit do not reflect either of these EPA recommendations.
The City believes the permit limit for cyanide was wrongly calculated also. The EPA
developed the cadmium criteria using measurements of free cyanide not total cyanide.
See, Ambient Water Quality Criteria for Cyanide - 1984, USEPA, Criteria and Standards
Division, Jan. 1985. The DEM, however, has taken this measurement of free cyanide and
used it to calculate a permit limit expressed in terms of total cyanide without using a
translation formula. The permit limit, therefore, overstates the bioavailable cyanide in the
effluent.

Mr. David A. Goodrich
July 14, 1994
Page 3
3. Historically, the City has not been required to sample at location 3, the mouth of
Grants Creek, from November through March. Location 3 can only be accessed by boat
from the Yadkin River. The draft permit, however, seems to require weekly sampling at
this location, even during the winter months (November through March). This new
requirement is unjustified; it will pose an unacceptable safety risk for the City's personnel
given the high river levels and potential for hypothermia in case of an accident. Because
the City will be sampling at two other locations during this time, it is not reasonable to
require sampling from this hazardous location during the winter months.
4. Part II, Section C7 of the draft permit requires the City to maintain safeguards in
case of electrical power failures. While the City has a stand-by generator at the plant, it is
not powerful enough to comply with this new requirement if there is a power outage
greater than four hours. The City, therefore, plans to acquire a new generator capable of
providing significantly more stand-by power. Monies for this project will come from an
upcoming bond project. The City, therefore, requests a compliance schedule for this
provision until these upgrades are completed.
Thank you for your consideration of these matters. The City would like to meet with the DEM
staff to discuss these concerns before a final permit is issued.
Sincerely,
John C. Vest, P. E.
Utilities Director
JCV:sph
pc: Mayor Margaret Kluttz
City Manager, David W. Treme
City Council
Rex Gleason, Mooresville Regional Office