NC0089532_Fact Sheet_20150706

MIS
DENR/DWR
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES No. NCO089532
Facility Information
Name:
Tuckaseigee Water and Sewer Authority (TWSA)
Mcility
ddress:
1246 West Main St.SylvaNC 28779
ress:
Hi hway 64, east of Cashiers
ow
0.495 MGD
T e of Waste:
Domestic/commercial
Facility/Permit Status:
Grade 2/Minor/New
County:
Jackson
Miscellaneous
Receiving Stream:
Horsepasture River
Regional Office:
Asheville
Stream Classification:
C-Tr +
USGS Quad:
Big Ridge
303(d) Listed?
No
Permit Writer:
Teresa Rodrizuez
HUC:
03060101
Date:
Sub -basin
03-13-02
. vdlqp�
Lat. 35° 07' 46" N Long. 83° 04' 00" W
Drainage Area (mi`):
3.9
Summer 7Q 10 (cfs)
2
Winter 7Q10 (cfs)
3
30Q2 (cfs) 14.3
Average Flow cfs):
16
IWC (%):
27
SUMMARY
The Tuckaseigee Water and Sewer Authority (TWSA) operates a 0.200 MGD WWTP permitted under
permit NCO063321 discharging to the Chattooga River. The WWTP serves the unincorporated Cashiers
area. TWSA is proposing to expand the capacity of the treatment system in order to accommodate
existing and future allocations in the Cashiers area. TWSA proposes to build a new 0.495 MGD WWTP
discharging to Horesepasture River. The Chattooga River is classified as ORW therefore an expansion of
the existing WWTP is not allowed.
EAA
The Division issued speculative limits for 0.495 MGD in April 2014. TWSA developed an Engineering
Alternative Analysis (EAA) for the proposed discharge. The Cashiers WWTP currently serves
approximately 250 customers. Current flows average 0.102 MGD during high season. TWSA holds
requested allocations for connecting to the sewer system of 0.104 MGD. Future flow needs for the next
20 years were estimated based on requested allocations, planned development in the Cashiers Commercial
District service area and surveyed potential customers expressing desire to connect to the sewer system.
Currently most residential lots are serviced by individual septic systems, some of which are failing. The
flow projection for the 20 year period is 0.695 MGD. The existing WWTP has a capacity of 0.20 MGD,
the new plant will treat the remaining 0.495 MGD.
The following alternatives were considered by TWSA:
1. No action — this alternative will not meet the growth and service needs of the area. Present Worth not
applicable.
2. Optimization of WWTP — the existing facility does not have the capabilities to treat flows in excess
of 0.2 MGD. This alternative is not feasible.
3. Land application — Based on local soils, hydrology and slopes a land application system in this
region of the mountains will require 60 days storage capacity and 140 acres for operation of a spray
$ 3- 762,10_y system. The present worth of this alternative is $23,762,105.
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NPDES NCO089532
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4. Reuse system — There are not any industrial uses or golf courses in the service area that could use
reclaimed water from the treatment system. This alternative was not considered feasible.
5. New regional WWTP — The Town of Highlands is the close treatment system in the area. The
WWTP is 11 miles away. The Town of Highlands is not supportive of regionalizing their WWTP.
The present worth of this alternative is $23,830,610.
6. Upgrade existing plant to 0.695 MGD, discharge 0.0495 MGD to Horsepasture River — The existing
treatment system would be expanded to 0.695 MGD using a Membrane Bioreactor. Due to the
limitation of space it is the only technology that could be used for expansion. Under this alternative
0.2 MGD will be discharged to Chattooga River and 0.495 MGD to Horsepasture River. The present
worth of this alternative is $11,363,624.
7. New 0.495 MGD WWTP discharging to Horsepasture River — The existing WWTP discharges to the
Chattooga River which is classified as ORW. Under existing rules no expansions are allowed in
ORW waters. The proposed discharge is to Horsepasture River is downstream at the end of the
service area. The present worth of this alternative is $10,271,391.
The construction of a new 0.495 MGD WWTP discharging to Horsepasture River is the most
economically and environmentally feasible of the options evaluated. The preliminary treatment system
description includes equalization, tertiary treatment and UV disinfection.
RECEIVING STREAM
Horsepasture River is located within the Savannah River Basin, subbasin 03-13-02, stream index 4-13-
(0.5), HUC 03060101. Horsepasture River has a classification of C, TR +, which is subject to special
management strategy specified in 15A NCAC 2B .0225 (13), the Outstanding Resource Wastewater Rule.
PROPOSED PERMIT LIMITS AND CONDITIONS
As specified in 15A NCAC 2B .0225 (13) all new or expanding discharges to this section of Horsepasture
River shall comply with the following requirements:
(A) Oxygen Consuming Wastes: Effluent limitations shall be as follows: BOD = 5 mg/l, and NH3-N = 2
mg/l;
(B) Total Suspended Solids: Discharges of total suspended solids (TSS) shall be limited to effluent
concentrations of 10 mg/1 for trout waters and to 20 mg/l for all other waters except for mining
operations, which will be held to their respective NPDES TSS permit limits;
(C) Nutrients: Where nutrient overenrichment is projected to be a concern, effluent limitations shall be
set for phosphorus or nitrogen, or both; and
(D) Volume: The total volume of treated wastewater for all discharges combined shall not exceed 25
percent of the total instream flow in the designated ORW under 7Q10 conditions.
The limits for BOD, TSS and ammonia follow the requirements in the rule. At the designated ORW the
total volume of wastewater is 24%.
Other permit limits and conditions:
• WET: The draft permit will not include Whole Effluent Toxicity test since it is not required for
minor facilities.
• TRC: Since disinfection will be accomplished using UV no limit for total residual chlorine was
included.
• Instream monitoring: The permit includes instream monitoring for temperature and dissolved
oxygen as per 15A NCAC 2B .0200.
• Mercury: Since this is a new facility and is less than 1 MGD the implementation guidance for the
statewide Mercury TMDL requires one sample every 5 years.
• The permit includes a special condition with requirements for submitting electronic DMRs.
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NPDES NCO089532
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Table 1. Summary of mMosed permit limits and monitoring
Parameters Affected
Permit Limit/Condition
Basis for Condition
Flow
0.495 MGD
Design flow; T15A 2B .0505
BOD5
5 mg/l MA
7.5 mg/l WA
Management Strategy from 15A NCAC 2B
.0225 (13)
NH3-N
2 mg/l MA
6 mg/1 WA
Management Strategy from 15A NCAC 2B
.0225 (13)
TSS
10 mg/l MA
15 mg/l WA
Management Strategy from 15A NCAC 2B
.0225 (13)
Fecal coliform
200/100 ml MA
400/100 ml WA
State WQ standards, 15A 2B .0200
Dissolved Oxygen
6 mg/l DM
State WQ standards, 15A NCAC 2B .0200
Temperature
Daily Monitoring
15A NCAC 02B .0508
Total Nitrogen/Total
Phosphorus
Monthly monitoring
15A NCAC 02B .0508
MA — Monthly Average WA — weekly average DM — Daily Maximum
PROPOSED SCHEDULE FOR PERMIT ISSUANCE
Draft Permit to Public Notice: April 7, 2015
Permit Scheduled to Issue: June 1, 2015
NPDES DIVISION CONTACT
If you have questions regarding any of the above information or on the attached permit, please contact
Teresa Rodriguez at 919-807-638T
NAME: DATE: T1115-
f
Regional Office Comments
NAME:
SUPERVISOR:
Y
TE:
DATE:
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NPDES NCO089532
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