NC0026646_Fact Sheet_19971014

NPDES DOCUMENT !MCANNIN` COVER SHEET
NPDES Permit:
NC0026646
Pilot Mountain WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
5 6 f 54 e /
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
October 14, 1997
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DEHNR/DWQ
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NPDES No. NC0026646
Fie Ci10;1a
RECEIVED
RP. Dept. of EHNR
S E P 2 5 1997
Applicant/Facility Name:
Town of Pilot Mountain
Applicant Address:
Post Office Drawer AA .
Facility Address:
Lynchburg Road, Pilot Mountain
Permitted Flow
1.5/3.0 MGD
Type of Waste:
Domestic-45%, Industrial-55% (estimate)
Facility/Permit Status:
Existing/Renewal
County:
Surry
Stream
Characteristics
Receiving Stream
Ararat River
Stream Classification
C
Subbasin
03-07-03
Drainage Area (mi2):
287
Summer 7Q10 (cfs)
82.2
Winter 7Q10 (cfs):
163
Average Flow (cfs):
379
IWC at 1.5/3.0 MGD (%):
2.75/5.35
Miscellaneous
Regional Office:
Winston-Salem
USGS Topo Quad:
B16SE
WLA Summary
BOD and TSS are effluent limited and will remain unchanged in the proposed permit.
The ammonia toxicity mass balance calculation using S7Q10 and permitted flows indicated
that the ammonia limits will also remain unchanged from the previous permit period: 28.6
mg/1 (summer at 1.5 MGD) and 15.0 mg/1 (summer at 3.0 MGD) and no limits in the
winter.
The chlorine toxicity mass balance calculation using S7Q10 and permitted flows indicated
very high chlorine limits and thus the cap of 28 ug/1 will remain unchanged in the permit.
Total nitrogen effluent concentrations ranged from about 5-14 mg/1 and total phosphorus
effluent concentrations ranged from 2-5 mg/1, but the treatment system does not discharge
into a nutrient limited stream. Thus, these concentrations are not expected to adversely
impact the receiving stream.
Recommend the temperature footnote be eliminated from the permit because
this is not a thermal discharge.
©3IW2
POINT SOURCE BRANCH
Page 1 of 4

1
The reasonable potential analysis was conducted for 1.5 and 3.0 MGD and results can be
summarized as follows:
Name r
: No: of,: Detects
1.5 MGD
MPC>AEC
3.O MGD
MPC>AEC
Cadmium
4 out of 31
Chromium
23 out of 31
MPC<AEC
MPC<AEC
Copper
24 out of 24
MPC>AEC
MPC>AEC
Cyanide
9 out of 32
MPC>AEC
MPC>AEC
Lead
9 out of 31
MPC<AEC
MPC<AEC
Mercury
0 out of 31
MPC<AEC
MPC<AEC
Nickel
3 out of 31
MPC<AEC
MPC<AEC
Silver
7 out of 23
MPC>AEC
MPC>AEC
Zinc
23 out of 23
MPC<AEC
MPC<AEC
: maximum predicted concentration
AEC: allowable effluent concentration
Those parameters indicated in bold will be limited. The Long Term Monitoring Plan
(LTMP) requires monitoring for all of the parameters listed in the above table. Monitoring
(but no limit) will be required for copper and silver. Although the MPC exceeded the AEC
for these two parameters, they do not have water quality standards, only action levels.
The Pretreatment Allocation table indicates that copper, cyanide, lead, and zinc are expected
to be discharged from the three industries which discharge to Pilot Mountain WWTP.
Pretreatment is investigating the source of cadmium.
1995 and 1996 APAM data were reviewed. Parameters in summary table include those:
(1) above the detection limit, and (2) for which monitoring is not required in either the
NPDES permit or the pretreatment permit (LTMP).
Name
w-:.:. .. .. ... ...._ ........ ..
10/95
... .:.:.T .x,.....
11/96-{1
::.., ..t
WQ Std or:*,
Fed Criteria
- . .v
AEC/1.5MGD :
�5 .......... ::
- +. .... ..
AEC/3.0MGD7
� � �� �tixelf
y.s.... s ... . .......
Aluminum
310
590
acute 750
chronic 87
chronic 3163
chronic 1625
Antimony
46
245
4300 OC
not calculated
not calculated
Arsenic
BDL
194
50 aql
1818
933
Selenium
4.2
175
5 aql
182
93
Barium
35
39
2000 MCL
not calculated •
not calculated
Chloride
62000
52100
acute860000
chronic230000
not calculated
not calculated
Fluoride
950
730
1800 aql
not calculated
not calculated
Bromodichlo
romethane
23.2
BDL
22,46q
not calculated
not calculated
Bromoform
1.2
BDL
360
not calculated
not calculated
Chloroform
23.4
BDL
34
not calculated
not calculated
Dibromochlo
romethane
10.6
BDL
470
not calculated
not calculated
OC: Organism Consumption
aql: aquatic life criteria
ABC:: Allowable Effluent Concentration
BDL: Below Detection Level
MCL: Maximum Contaminant Level
q: Value determined after federal criteria published, or new cancer potency slope factor
All concentrations are in ug/l unless indicated otherwise.
Page 2 of 4

Selenium monitoring will be required (but not limited) because the 1996 detection was
greater than the allowable effluent concentration at 3.0 MGD. Although the arsenic
detection was well below the allowable effluent concentrations at both 1.5 and 3.0 MGD,
its concentration was well above the water quality standard. Thus, it is considered a
pollutant of concern and monitoring (but no limit) will be required. Monitoring will not be
required for any other inorganic parameters detected during the APAM analyses because
allowable effluent concentrations are significantly greater than detected concentrations. In
addition, for these other inorganic parameters, the detections were also below the water
quality standards.
Bromodichloromethane, bromoform, chloroform, and dibromochloromethane were all
detected at concentrations less than 50 ug/l during the 1995 APAM sampling event. At
those concentrations, it is expected that these four compounds originated from formation of
chlorine with organic matter (i.e.are likely disinfection by-products). All four of these
compounds are carcinogens, yet monitoring will not be required for the following two
reasons:
1) Concentrations detected were below federal criteria, and
2) None of the four compounds were detected during most recent APAM sampling event.
The APAM will no longer be required in the NPDES permit.
Instream Monitoring
Review of instream data from January 1995 through May 1997 indicates that the discharge
generally does not appear to be having an adverse impact on the receiving stream. There
are a few instances (5/21,22/96 and 8/19-21/96) where fecal coliform may have had an
adverse impact on the stream. The facility is conducting instream monitoring for dissolved
oxygen although is not required.
Compliance Summary
On October 1, 1996, the SOC expired and the final limits for Pilot Mountain became
effective. Review of compliance data for the period May 1996 - March 1997 indicated the
following violations: NH3N monthly average violations (9/96, 10/96), TSS monthly
average violations (8/96, 11/96), TSS weekly average violation (9/16-20), BOD weekly
average violation (1/6-10), fecal coliform weekly average violations (8/19-23, 11/4-8) and
fecal coliform daily maximum violation (10/1/96).
The facility has passed the majority of its toxicity tests (Chronic), but most recently failed
in July 1996.
Average flows at the treatment facility indicate they are operating under a permitted flow of
1.5 MGD.
Proposed Schedule for Permit Issuance
Draft Permit to Public Notice:
Permit Scheduled to Issue:
124197"--
This permit should not expire until June 30, 1999 according to the basin
plan, but it is currently scheduled to expire January 31, 1998. 9/22/97 - D.
Goodrich gave approval to notice under existing schedule.
Page 3 of 4

Other
Special Condition I - Engineering Alternatives Analysis Condition has been eliminated
because it is incorporated into another section of the permit.
State Contact
If you have any questions on any of the above information or on the attached permit, please
contact Paul Clark at [phone], extension 580.
Copies of the following are attached to provide further information on
permit development:
1. Compliance data
2. Reasonable potential analysis,
3. Existing permit effluent sheets, and
4. Proposed draft permit.
Special Schedule Requirements and additional comments from Reviewers:
e/diA�
Recommended by: Date:
Reviewed by
'A4 Regional Supervisor: ,LDS ) Date: D 0 i
NPDES Unit Supervisor: Date:
Page 4 of 4

9�23/93- fry .o.Cea- ws2 D
NC0026646 Summary
July 25, 1997
August 27, 1997 (revised)
E(Zfli 7 Su/i/v1 Y •
PCR/1/ 7 <,✓� l i 'S
7VU-77
Town of Pilot Mountain has applied to renew their permit to discharge 1.5/3.0 MGD
treated wastewater.
The treatment system consists of an influent pump station, grit chamber, lint screening unit,
chemical addition, oxidation ditch, two clarifiers, chlorination, step reaeration, an aerated
sludge holding unit and vacuum drying beds.
As of July 1996, the outfall was relocated to Ararat River (Class C) in the Yadkin -Pee Dee
River asin (sub -basin 030703). This permit should not expire until June 1113o)gg
1 according to the basin plan, but in reality it expires January 31, 1998..r�.�1
Industries (all SIUs) discharging to Pilot Mountain WWTP include:
1. Wellington Leisure Products: product - rope products, rm: polypropylene, Aele-6144
polyethylene, PVC homopolymer, wwc - BOD, TSS, NHS-N, COD, Cu, Zn, Ni, Hg. n/ 1 /1 y 7.
2. Intex Corp.: product - fabric finishing, rm: see application, wwc - BOD, TSS, NHS-3,
Cu, Zn, Ni, Hg.
3. Armtex Corp: product - cotton, cotton polyester, acrylic yarn, dye, chemicals,
polyester, wwc - information not provided.
SIU: Significant Industrial User
To be classified as a SIU, an industry must meet one or more of the following conditions:
1) Flow to POTW > 25,000 GPD
2) Flow to POTW > 5% of POTW's Maximum Allowable Headworks Loading (MAHL)
3) Industry is a classified Categorical Industry (CI)
4) Other - an industry may not meet nos. 1-3 listed above, but if there is a concern that the
industry may adversely impact the POTW, it can be classified as a SIU and thus a
pretreatment permit is required.
Only the SIU dischargers have pretreatment permits.
Compliance Summary
On October 1, 1996, the SOC expired and the fmal limits for Pilot Mountain became
effective. Review of compliance data for the period May 1996 - March 1997 indicated the
following violations: NH3N monthly average violations (9/96, 10/96), TSS monthly •
average violations (8/96, 11/96), TSS weekly average violation (9/16-20), BOD weekly
average violation (1/6-10), fecal coliform weekly average violations (8/19-23, 11/4-8) and
fecal coliform daily maximum violation (10/1/96).
The facility has passed the majority of its toxicity tests (Chronic), but most recently failed
in July 1996.
Average flows at the treatment facility indicate they are operating under a permitted flow of
1.5 MGD.
Instream Monitoring
Review of instream data from January 1995 through May 1997 indicates that the discharge
does not appear to be having an adverse impact on the receiving stream. There are a few
instances (5/21,22/96 and 8/19-21/96) where fecal coliform may Have had an adverse
impact on the stream. The facility is conducting instream monitoring for dissolved oxygen
although is not required.
Page 1 of iff,

NC0026646 Summary
July 25, 1997
August 27, 1997 (revised)
WLA Summary
BOD and TSS are effluent limited and will remain unchanged in the proposed permit.
The ammonia toxicity mass balance calculation using S7Q 10 and permitted flows indicated
that the ammonia limits will also remain unchanged from the previous permit period: 28.6
mg/1 (summer at 1.5 MGD) and 15.0 mg/1 (summer at 3.0 MGD) and no limits in the
winter.
The chlorine toxicity mass balance calculation using S7Q 10 and permitted flows indicated
very high chlorine limits and thus the cap of 28 ug/1 will remain unchanged in the permit.
Total nitrogen effluent concentrations ranged from about 5-14 mg/1 and total phosphorus
effluent concentrations ranged from 2-5 mg/1, but the treatment system does not discharge
into a nutrient limited stream. Thus, these concentrations are not expected to adversely
impact the receiving stream.
Recommend the temperature footnote be eliminated from the permit because
this is not a thermal discharge.
The reasonable potential analysis was conducted for 1.5 and 3.0 MGD and results can be
summarized as follows:
Name..:: -'
No _ of - Detects
1.5 _; MGD.
-3.0: MGD:_;:
Cadmium
4 out of 31
MPC>AEC
MPC>AEC
Chromium
23 out of 31
MPC<AEC
MPC<AEC
Copper
24 out of 24
MPC>AEC
MPC>AEC
Cyanide
9 out of 32
MPC>AEC
MPC>AEC
Lead
9 out of 31
MPC<AEC
MPC<AEC
Mercury
0 out of 31
MPC<AEC
MPC<AEC
Nickel
3 out of 31
MPC<AEC
MPC<AEC
Silver
7 out of 23
MPC>AEC
MPC>AEC
Zinc
23 out of 23
MPC<AEC
MPC<AEC
MPC: maximum predicted concentration
AEC: allowable effluent concentration
Those parameters indicated in bold will be limited. The Long Term Monitoring Plan
(LTMP) requires monitoring for all of the parameters listed in the above table. Monitoring
(but no limit) will be required for copper and silver. Although the MPC exceeded the AEC
for these two parameters, they do not have water quality standards, only action levels.
The Pretreatment Allocation table indicates that copper, cyanide, lead, and zinc are expected
to be discharged from the three industries which discharge to Pilot Mountain WWTP.
Pretreatment is investigating the source of cadmium.
Page 2 of

NC0026646 Summary
July 25, 1997 •
August 27, 1997 (revised)
1995 and 1996 APAM data were reviewed. Parameters in summary table include those:
(1) above the detection limit, and (2) for which monitoring is not required in either the
NPDES permit or the pretreatment permit (LTMP).
Namea
10/95 •r
:..
11/96
:. .
Std or ,:
Fed Criteria
AEC/1.5MGD
r 7
AEC/3.0MGD
Aluminum
310
590
acute 750
chronic 87
chronic 3163
chronic 1625
Antimony
46
245
4300 OC
not calculated
not calculated
Arsenic
BDL
194
50 aql
1818
933
Selenium
4.2
175
5 aql
182
93
Barium
35
39
2000 MCL
not calculated
not calculated
Chloride
62000
52100
acute860000
chronic230000
not calculated
not calculated
Fluoride
950
730
1800 aql
not calculated
not calculated
Bromodichlo
romethane
23.2
BDL
22,46q
not calculated
not calculated
Bromoform
1.2
BDL
360
not calculated
not calculated
Chloroform
23.4
BDL
34
not calculated
not calculated
Dibromochlo
romethane
10.6
BDL
470
not calculated
not calculated
OC: Organism Consumption
aql: aquatic life criteria
AIL: Allowable Et'tluent Concentration
BDL: Below Detection Level
MCL: Maximum Contaminant Level
q: Value determined after federal criteria published, or new cancer potency slope factor
All concentrations are in ug/1 unless indicated otherwise.
Selenium monitoring will be required (but not limited) because the 1996 detection was
greater than the allowable effluent concentration at 3.0 MGD. Although the arsenic
detection was well below the allowable effluent concentrations at both 1.5 and 3.0 MGD,
its concentration was well above the water quality standard. Thus, it is consideered a
pollutant of concern and monitoring (but no limit) will be required. Monitoring will not be
required for any other inorganic parameters detected during the APAM analyses because
allowable effluent concentrations are significantly greater than detected concentrations. In
addition, for these other inorganic parameters, the detections were also below the water
quality standards.
Bromodichloromethane, bromoform, chloroform, and dibromochloromethane were all
detected at concentrations less than 50 ug/1 during the 1995 APAM sampling event. At
those concentrations, it is expected that these four compounds originated from formation of
chlorine with organic matter (i.e.are likely disinfection by-products). All four of these
compounds are carcinogens, yet monitoring will not be required for the following two
reasons:
1) Concentrations detected were below federal criteria, and
2) None of the four compounds were detected during most recent APAM sampling event.
The APAM will no longer be required in the NPDES permit.
Page 3 of /37

Town of Pilot Mountain
NC0026646
Qeff=1.5 MGD
Qeff=3.0 MGD
Residual Chlorine
7Q10 (CFS)
DESIGN FLOW (MGD)
DESIGN FLOW (MGD)
DESIGN FLOW (CFS)
DESIGN FLOW (CFS)
STREAM STD (UG/L)
UPS BACKGROUND LEVEL (UG/L)
IWC (%)
Allowable Concentration (ug/l)
Allowable Concentration (ug/l)
Fecal Limit
Dilution=7Q10S/DESIGN FLOW
Dilution=
Dilution < 67, thus fecal limit
Ammonia as NH3
(summer)
82.2 7Q10 (CFS)
1.5 DESIGN FLOW (MGD)
3 DESIGN FLOW (MGD)
2.325 DESIGN FLOW (CFS)
4.65 DESIGN FLOW (CFS)
17.0 STREAM STD (MG/L)
0 UPS BACKGROUND LEVEL (MG/L)
2.75 IWC (%)
618.03 Allowable Concentration (mg/1)
317.52 Allowable Concentration (mg/1)
200 mg/1
35.4
Ammonia as NH3
(winter)
7Q10 (CFS)
DESIGN FLOW (MGD)
DESIGN FLOW (MGD)
DESIGN FLOW (CFS)
DESIGN FLOW (CFS)
STREAM STD (MG/L)
UPS BACKGROUND LEVEL (MG/L)
IWC (%)
Allowable Concentration (mgll)
Allowable Concentration (mgll)
82.2
1.5
3
2.325
4.65
1.0
0.22
2.75
28.58
14.79
163
1.5
3
2.325
4.65
1.8
0.22
1.41
112.57
57.18
7/25/97

Pilot Mountain, Town of
NC0026646
Qeff=1.5 MGD
Qeff=3.0 MGD
Aluminum
7Q10 (CFS)
DESIGN FLOW (MGD)
DESIGN FLOW (MGD)
DESIGN FLOW (CFS)
DESIGN FLOW (CFS)
STREAM STD (UG/L)
UPS BACKGROUND LEVEL (UG/L)
IWC (%)
Allowable Concentration (ug/I)
Allowable Concentration (ug/l)
82.2
1.5
3
2.325
4.65
87.0
0
2.75
3162.87
1624.94
Selenium
7Q10 (CFS)
DESIGN FLOW (MGD)
DESIGN FLOW (MGD)
DESIGN FLOW (CFS)
DESIGN FLOW (CFS)
STREAM STD (MG/L)
UPS BACKGROUND LEVEL (MG/L)
IWC (%)
Allowable Concentration (mg/I)
Allowable Concentration (mg/l)
Arsenic
7Q10 (CFS)
DESIGN FLOW (MGD)
DESIGN FLOW (MGD)
DESIGN FLOW (CFS)
DESIGN FLOW (CFS)
STREAM STD (MG/L)
UPS BACKGROUND LEVEL (MG/L)
IWC (%)
Allowable Concentration (mg/l)
Allowable Concentration (mg/I)
82.2
1.5
3
2.325
4.65
5.0
0
2.75
181.77
93.39
82.2
1.5
3
2.325
4.65
50.0
0
2.75
1817.74
933.87
7/25/97