NC0065684_Staff Comments_20010105

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Division of Water Quality
Point Source Branch/NPDES Unit
January 5,2001
ul u I t : U1 Jul
To: Tommy Stevens
Through: Coleen Sullins
Bill Reid
Dave Goodrich
From: Tom Belnick
Subject: Goose Creek NPDES Permitting Policy
Yadkin Pee Dee River Basin (Subbasin 030712)
Union County
Goose Creek is an environmentally sensitive waterbody with the presence of endangered species and an
impaired use support rating. This NPDES pernutting policy was developed specifically for current and
proposed future wastewater dischargers to Goose Creek, and will remain in effect until water quality
improvements are documented. Long-range plans include elimination of all small dischargers in the
Goose Creek watershed by connecting to a proposed regional facility.
Stream Data. Goose Creek, a Class C waterbody with headwaters in Mecklenburg County, flows through
Union County before joining Rocky River. The creek is inhabited by a small population of the federally
endangered freshwater mussel Carolina heelsplitter (Lasmigona decorata), which was listed as an
endangered species in 1993. A small number of individuals have also been reported in Duck Creek, a
tributary to Goose Creek. The decline in the species has been attributed to a combination of urban growth
pressures, wastewater dischargers, and agricultural activities.
The entire Goose Creek waterbody is listed in the North Carolina Draft 2000 303(d) list as biologically
impaired waters, and was designated by DWQ as one of the top five priorities among all the waters on the
1998 303(d) listing. A "poor" bioclassification was assigned to Goose Creek based on 1996 benthic
macroinvertebrate data, and a 1998 biological assessment conducted by the Division's Environmental
Sciences Branch found few benthic macroinvertebrates despite generally good habitat (see Attachment
A). The current use support rating is NS (Not Supporting).
Goose Creek is approximately 17 miles in length, with a drainage area of 42 square miles and an
estimated s7Q10 flow of 0.52 cfs at its confluence with Rocky River. Currently, there is an irrigation
withdrawal from Goose Creek for a golf course at approximately mid -length during summer months of up
to 188 gpm (0.42 cfs), which can significantly affect the available dilution for downstream dischargers.
Time of travel dye studies revealed that the average stream velocity in Goose Creek is very slow,
particularly in the lower half (0.05 fps).
NPDES Discharger Status. There are currently six permitted dischargers of treated domestic wastewater
to Goose Creek or its tributaries (i.e., Stevens Creek, Paddle Creek, Duck Creek); refer to Table 1.
Pemrittees include 5 subdivisions and 1 school, with permitted flows ranging from 0.004 - 0.67 MGD.
Based on the Union County Sewer System Master Plan (1996), long range plans for the Goose Creek
drainage basin include construction of a new Rocky River Regional W WTP, which would include an
activated sludge plant with nutrient removal, tertiary filtration, and UV disinfection. The proposed
Goose Creek NPDES Policy
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regional outfall would be located at the confluence of Goose Creek and Rocky River. Presently several
Goose Creek dischargers are evaluating alternative discharge options.
OUAL2E Model Results. The Modeling/TMDL Unit developed a QUAL2E model for Goose Creek to
evaluate potential impacts of existing domestic dischargers on instream dissolved oxygen (DO) levels.
Model results indicate that Goose Creek is over -allocated at current permitted limits, with DO
concentrations predicted to drop below the instream water quality standard of 5 mg/l during summer low
flow conditions along a 3.8-mile downstream segment. Actual instream DO data from DMR reports and
a 1997 intensive survey showed no DO violations; however, more recent data collected during Summer
2000 by the Yadkin -Pee Dee River Basin Association show some instream DO values at or below 5.0
mg/l at Stations Q8360000 and Q8359000 in Goose Creek. The modeling report notes that there are
model uncertainties due to the slow time of travel, particularly in the lower half. A summary of model
results is included as Attachment B.
Basin Plan Recommendations. The 1998 Basin Plan reports that "elevated fecal coliform levels are likely
primarily due to nonpoint sources, while the cumulative effect of elevated chlorine and ammonia levels
from the small wastewater dischargers may also be affecting the aquatic community of Goose Creek."
The 1998 Basin Plan recommended that 1) existing facilities discharging into Goose Creek receive TRC
limits at permit renewal; 2) DWQ be supportive of efforts to eliminate the small discharges in the Goose
Creek watershed by connecting to the proposed Rocky River regional VWVTP in 2000 to 2010.
Agency Comments. A meeting was held on July 7, 2000, with staff from the U.S. Fish and Wildlife
Service (USFWS) and the North Carolina Wildlife Resources Commission (WRC). The purpose of the
meeting was to seek agency comments on a proposed NPDES permitting strategy for Goose Creek.
Primary agency concerns focused on potential toxic impacts to the endangered mussel populations from
direct wastewater dischargers. WRC provided maps of Goose Creek mussel distributions and
abundances, which suggest impairment to mollusk populations below point source discharges. Both
USFWS and WRC were opposed to any additional hydraulic expansions. USFWS recommended
instream monitoring for toxic constituents (TRC, ammonia) to be added to the existing permits.
Attachment C includes agency comments and maps.
NPDES PERMITTING POLICY
As a result of the presence of endangered species, an impaired use support rating, and model results
indicating current overallocation, the following NPDES permitting policy for NPDES-permitted
dischargers to the Goose Creek drainage will be effective immediately and remain in effect until water
quality improvements are documented:
New Facilities and Expansions. No new or expanding dischargers will be allowed. This moratorium
on additional hydraulic and pollutant loading can be revisited after sources of water quality
impairment are well characterized, strategies are implemented to reduce that impairment, and water
quality has been demonstrated to improve.
Existing Facilities: Refer to Table 1 for a summary of proposed changes at permit renewal. Existing
facilities will receive TRC limits (minimum of 17 ug/1, with upper cap = 28 ug/1) if they are not
already present, and ammonia limits will be adjusted according to mass balance calculations to
protect for ammonia toxicity. To account for the decreased streamflow during summer irrigation for
the single existing facility located downstream of the golf course withdrawal (i.e., Fairview
Elementary, NCO030538), a s7Q10 flow of 0.10 cfs will be used in limits development for TRC and
NH3. Compliance schedules may be included in permits to allow for securement of an ATC permit
and installation of equipment, if needed, to meet potential new permit limits for TRC and NH3. Also,
summer instream monitoring (U,D) for TRC and NH3 will be added to each permit at the current
Goose Creek NPDES Policy
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instream monitoring frequency, in order to evaluate whether instream criteria are being maintained.
Instream monitoring for TRC and NH3 may be removed at the next permit cycle, if data show no
instream problems. Current effluent BOD limits will remain unchanged with one exception; for the
already permitted phased 0.35 MGD flow at NC0072508, the BOD limit will be changed from 30
mg/l down to 5 mg/1. Nutrient monitoring (TN,TP) appropriate for the permitted flow will be
maintained. Finally, the following language will be added to each permit cover letter: " Please note
that Goose Creek is listed in the Draft 2000 303(d) list as a biologically impaired water based on
benthic macroinvertebrate data. The stream is also listed as impaired due to excessive instream
fecal coliform concentrations. In addition, Goose Creek is considered environmentally sensitive
due to the presence of the federally endangered freshwater mussel Carolina heelsplitter. If
degradation of the stream can be attributed to point source dischargers, then mitigative
measures, including the removal of the discharge, may be necessary. Finally, based on the
Goose Creek NPDES Permitting Policy, no new or expanding wastewater discharges will be
allowed until instream water quality improvements are documented."
The Point Source Branch requests your comments and concurrence with our permitting policy. You
should note that the Division has three requests that would be denied as a result of this policy: 1) Goose
Creek Utility Company (NC0034762) has requested an increase in permitted flow from 0.07 to 0.095
MGD to accommodate hydraulic loading from infiltration/inflow; 2) Heater Utility/Country Wood
(NC0065684) has requested an increase in permitted flow from 0.67 to 0.70 MGD to accommodate future
development; and 3) Howie Bottoms (NC0086282) submitted an application for a proposed subdivision
wastewater discharge in January 1998, but the application has been held pending complete submission.
Please feel free to call me at extension 543 if you have any questions or comments.
cc: (without attachments)
Tom Augspurger, USFWS
Frank McBride, NCWRC
Mooresville Region, Water Quality
NPDES Unit staff
Andy McDaniel, ModelingrfMDL Unit
Basin Planning, Yadkin River Basin
Goose Creek NPDES Policy
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Table 1. NPDES- erntitted facilities in Goose Creek and Permit Renewal Strategy
Permit#
Facility
Permitted
Receiving
NH3-N Limit
TRC Limit
HOD Summer
Instream (U,D)
Flow (MGD)
Stream (cfs)
(summer/winter)
(Daily Max)
Limit
Monitoring
(Current and
-
Renewal
1. NC0072508
Union CO PWD-
Phased limits
Goose Creek
Current: 2/4 mg/l
Current: 20 ug/l
Current:30 mg/I
Renewal: Add
Hanley Cr.
0.231/0.35
S7Q10= 0.1
Renewal: 2/4 mg/I
Renewal: 20 ug/I
for both phases.
monthly TRC and
W7Q10=0.3
Renewal:
NH3-N.
Change 0.35
MGD phased
limit to 5 m
2. NC0034762
Goose Creek Util.
0.07
Goose Creek
Current: 5110 mg/I
Current: No Limit
16 mg/l
Renewal: Add
Co.
S7QIO= 0.1
Renewal: 2/7.6 mg/l
Renewal: 28 ug/l
monthly TRC and
(Requested
W7QI0=0.4
NH3-N.
increase to 0.095
(Basis- see IWC)
(Basis- CA= 33 ug/l,
not allowed)
thus set upper TRC
limit
3. NC0065684
Heater Utility.-
0.67
Goose Creek
Current: 2/4 mg/I
Current: 19 ug/l
10 mg/I
Renewal: Add
Country Wood
S7Q10= 0.1
Renewal: 2/4 mg/I
Renewal: 19 ug/I
monthly TRC and
(Requested
W7Q10=0.4
NH3-N.
increase to 0.70
not allowed
4. NC0030538
Union CO School-
0.004
Goose Creek
Current: No Limit
Current: No Limit
30 mg/l
Renewal: Add
Fairview Elem
S7Q10=0.36
Renewal: 13.6/NL
Renewal: 28 ug/l
monthly TRC and
W7QIO= 0.91
mg/I
NH3-N.
(Basis- CA= I004 ug/I
With withdrawal
(Basis- see IWC with
and CAw= 291 ug/I,
S7Q I O= 0.1
withdrawal factored
thus set upper TRC
W7 10= 0.4
in)
limit
5. NC0065749
Heater Utility-Ashe
0.100
Duck Creek
Current: 2/4 mg/l
Current: No Limit
5 mg/l
Renewal: Add
Plantation
S7Q10= 0
Renewal: 2/4 mg/1
Renewal: 17 ug/I
monthly TRC and
W7Q10= 0
NH3-N.
Basis- CA= 17 u
6. NC0063594
Heater Utility-
0.075
Stevens Creek
Current: 2/4 mg/l
Current: No Limit
11 mg/I
Renewal: Add
Oxford Glen
S7Q10= 0.05
Renewal: 2/4 m9/1
Renewal: 24 ug/l
monthly TRC and
W7QI O= 0.13
NH3-N.
(Basis- CA= 24 u 1
CA= Allowable effluent concentration at s7QIO flow
CA, = Allowable effluent concentration, with golf course irrigation withdrawal considered.
Goose Creek NPDES Policy
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