NC0044423_Corrective Action Plan_20200323

Appalachian
1 1 STATE UNIVERSITY
March 23,2020
Facilities Management
ASU Box 32105
Joe R.Corporon,L.G. Boone,NC 28608-2105
828-262-3190
Water Quality Permitting Section-NPDES facilitiesmanagement.appstate.edu
Division of Water Resources,NCDEQ
512 N Salisbury Street
Raleigh,NC 27604
Re: Corrective Action Plan RECEIVED
NPDES Permit No.NCoo44423 APR 0 2 2020
Appalachian State University WTP
NCDEQ/DWR/NPDES
Dear Mr.Corporon,
Per Condition A(3)of NPDES Permit No.NCoo44423,Appalachian State University(ASU)Water
Treatment Plant(WTP)is required to submit a Corrective Action Plan(CAP)annually"summarizing
actions to be taken to achieve compliance with Total Copper,Total Zinc,and Turbidity at Outfall oo1."
Enclosed herein is the Corrective Action Plan due April 1,2020.
Total Copper and Total Zinc
NCoo44423 includes the following numerical effluent limits for total copper and total zinc which become
effective January 1,2021:
Table i.Future Effluent Limits
Monthly Average,ug/1 Daily Maximum, ug/1
Total Copper 4 I 5.2
1
Total Zinc 6,3 63
Monthly effluent monitoring was conducted in accordance with the requirements of this permit.
Historical monitoring indicates at times the effluent concentrations exceed the numerical limits for
copper and zinc for both the monthly average and daily maximum.ASU conducted additional monitoring
from July 2019—January 2020 to characterize the background concentrations from the intake water and
the concentrations in the reservoir upstream and downstream of the intake and discharge,shown in
Figure 1. All of the data collected during the sampling program is provided in the attached Table 2 and
discussed below.
Copper
Figure 2 presents the mass of copper in the WTP intake and the mass of copper in the WTP effluent
discharge.A higher mass of copper was being drawn into the WTP than was discharged.For
the effluent,four of eight data points were below method detection limit.
A MEMBER INSTITUTION OF THE UNIVERSITY OF NORTH CAROLINA AN EQUAL OPPORTUNITY EMPLOYER

Figure 2. Mass of Copper in WTP Intake and Effluent
5
4.5
4
3.5
a 3
d 2.5 '.
o. 2
0
u
1.5
1E
0.5
7/1/2019 8/1/2019 9/1/2019 10/1/2019 11/1/2019 12/1/2019 1/1/201C
—*--WTP Intake WTP Discharge
NOTE:lb/d indicates pounds per day
The mass of copper that is being drawn into the intake but is absent in the discharge is expected to be
present in the sludge removed periodically from the facility for disposal offsite.Sampling performed in
February 2020 indicated average of 574 ug/1 of copper in the sludge at that time.
Sampling was also performed within the reservoir to evaluate the potential impact of the discharge on
instream water quality.Figure 3a presents the concentration of copper in the reservoir upstream and
downstream of the intake and discharge and the WTP effluent concentration.Of 13 downstream data
points,seven were below method detection limit and are plotted as the method detection limit.Of 13
upstream data point,five were below method detection limit and are plotted as the method detection
limit.
The axis scale of Figure 3a is skewed by two specific dates with higher instream concentration(7/1o/2019
and 11/6/2019).On 7/10/2019,the upstream and downstream copper are 195 ug/1 and 194 ug/l,trending
very well together while the WTP effluent was very low 41 ug/l. On 11/6/2019,the downstream copper
was 614 ug/1 while the effluent and upstream were both non-detect.It is not clear if the downstream
result is accurate or an anomaly,since generally upstream and downstream results have trended much
more closely.If the result is accurate,it indicates the WTP effluent,which was non-detect,was not likely
responsible for the high values.
Figure 3b shows the same copper data but with the data on 7/10/2019 and 11/6/2019 removed to better
observe trends for the lower concentration data. The upstream and downstream concentrations trend
very well together,with the downstream concentration often being a lower concentration that upstream.
In addition to the mass data demonstrating the WTP is on net removing metals from the reservoir,the
concentration data presented in Figure 3a and Figure 3b indicate the discharge is not having a negative
impact on instream copper concentration and the concentration downstream of the discharge is often
lower than upstream.
Page 2 of 6

Figure 3a. Copper Concentration in the Reservoir and Effluent(All Data)
700
600
500
400
6J
Q 300
0
200
100
0 "1110.-
7/1/2019 7/31/2019 8/30/2019 9/29/2019 10/29/2019 11/28/2019 12/28/2019 1/27/2020
—dr—Reservoir Upstream --I—Reservoir Downstream Effluent
Figure 3b. Copper Concentration in the Reservoir and Effluent
(Lower Concentration Date Only)
50
45
40
35
oa 30
a`, 25
c.
0 20
15
10 eo
5
7/1/2019 7/31/2019 8/30/2019 9/29/2019 10/29/2019 11/28/2019 12/28/2019 1/27/2020
—A—Reservoir Upstream Reservoir Downstream —I--Effluent
Page 3 of 6

Zinc
Figure 4 presents the mass of zinc in the WTP intake and the mass of zinc in the WTP effluent discharge.
A higher mass of zinc was being drawn into the WTP than was discharged.For the effluent,
three of eight data points were below method detection limit.
Figure 4.Mass of Zinc in the WTP Intake and Effluent
3
2.5
2
1.5
ti
1
0c,
0 L
7/1/2019 8/1/2019 9.'1,2019 10/1/2019 11/1/2019 12/1/2019 1/1/2020
—�WTP Intake —♦—WTP Discharge
NOTE:lb/d indicates pounds per day
The balance of the zinc is expected to be in the sludge removed periodically from the facility for disposal
offsite.Sampling performed in February 2020 indicated average of 556 ug/1 of zinc in the sludge at that
time.
Sampling was also performed within the reservoir to evaluate the potential impact of the discharge on
instream water quality.Figure 5 presents the concentration of zinc in the reservoir upstream and
downstream of the intake and discharge and the WTP effluent concentration.Of 13 downstream data
points,five were below method detection limit and are plotted as the method detection limit.Of 13
upstream data point,four were below method detection limit and are plotted as the method detection
limit.
The upstream and downstream concentrations trend very well together.On one occasion when the
downstream concentration was much higher than the upstream(11/6/2o19),the effluent concentration
was 48 ug/L,below the future limit.
In addition to the data demonstrating the WTP is on net removing metals from the reservoir,the
concentration data presented in Figure 5 indicates the discharge is not impactful on instream zinc
concentration.
Page 4 of 6

Figure 5. Concentration of Zinc in the Reservoir
4000
3500
3000
2500
OD
2000
u
C
N 1500
1000
500
7/1/2019 7/31/2019 8/30/2019 9/29/2019 10/29/2019 11/28/2019 12/28/2019
—A—Reservoir Upstream --♦-Reservoir Downstream —0—Effluent
Turbidity
NCoo44423 includes a numerical effluent limit for turbidity not to exceed io Nephelometric Turbidity
Units(NTU)which became effective July 1,2019.Effluent monitoring data collected in accordance with
the permit indicates the effluent turbidity at times exceeds the numerical limit.We also understand the
NC DEQ Changes to Water Treatment Plant Strategy(October 2009)states that"turbidity will not be
limited except for facilities that discharge to a receiving stream which is impaired for turbidity".Norris
Branch Reservoir is not included in the 3o3d Impaired Water Bodies List.The 10 NTU limit is based on
the instream water quality standard for Trout Waters and is being applied directly to the effluent allowing
no allowance for the dilution which occurs in the reservoir.
Turbidity data collected within the reservoir during the July 2019—January 2020 sampling period
indicate the water quality within the reservoir is below the 10 NTU stream standard,even when the
turbidity in the WTP effluent exceeds the instream standard.The upstream and downstream turbidity
data trend correlate well,indicating the WTP discharge does not have a meaningful impact on the
turbidity even when the effluent exceeds the 10 NTU numerical limit. Based on this recent data,it
appears the ASU WTP discharge is not increasing the instream turbidity above natural background
conditions or the instream water quality standard.Figure 6 presents a summary of the data collected.
Page 5 of 6

Figure 6.Turbidity Data
18
16
14
12
10
'5 6
4
2
0
7/1/2019 7/31/2019 8/30/2019 9/29/2019 10/29/2019 11/28/2019 12/28/2019
—0—Reservoir Upstream —0—Reservoir Downstream
—Water Quality Standard t Effluent
Permit Renewal
The NPDES permit is due for renewal on 3/21/2o2i.The ASU WTP is not a generator of copper and zinc
and the WTP is not discharging metals from another source.The parameters are present in the
source water withdrawn from the same water body they are being discharged back into.
Data collected from July 2o19—January 2020 and presented in Figures 2 and Figure 4
above support that the WTP on net removes metals from the surface water.It is not
appropriate to apply the same NPDES limit calculation methodology to a discharger that is withdrawing
the compounds from the same water body to which they discharge.As such,at the next permit renewal we
will request removal of the copper,zinc,and turbidity numerical limits.We will request the numerical
limits be replaced with monitoring requirements within the effluent and the reservoir.The monitoring
locations within the reservoir can be selected in order to best characterize what impact,if any,the
discharge has on instream water quality.
Should you have any comments or questions or require additional information,please feel free to contact
me at 828.262.8787.
Sincerely,
Patrick Brittain,PE
License No.022085
Asst.Director Facilities Operation and Maintenance
Cc. Lon Snider,PE,Regional Supervisor,NCDEQ
Jenny Graznak,Environmental Specialist,NCDEQ
Gary Carter,PE,Director Physical Plant,ASU
Leigh-Ann Dudley,PE,Engineering Consultant,Dewberry
Page 6 of 6

Figure 1.Sampling Locations and Frequency
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Location on Map Name of Sampling Location Sampling Frequency
A/1 In Lake Upstream of Intake Sample Twice a Month
B/4 Raw Water Intake Sample Twice a Month
C Effluent Sample Once a Month
D/2 Downstream of Discharge at Spillway Sample Twice a Month
E/3 CIP Tank Sample At Every CIP Discharge
2020
1

Table 2.Sampling Program Data
Sampling Location on Map A B C D
In Lake Upstream of Intake Raw Water Intake Effluent Downstream of Discharge at Spillway
Sample Twice Per Month Sample Twice Per Month Sample Once Per Month Per Permit Sample Twice Per Month
Sample Date
Total Copper Total Zinc Turbidity Total Copper Total Zinc Turbidity Total Copper Total Zinc Turbidity Copper Zinc Turbidity
ug/L ug/L NTU ug/L ug/L NTU ug/L ug/L NTU ug/L ug/L NTU
7/10/2019 195 509 1.9 41 118 8.1 194 473 0.86
7/24/2019 <1.0 3560 1.6 3.9 <1.0 3650 1.4
8/14/2019 <1.0 <1.0 7.6 2352 30 8.5 <1.0 <1.0 10.1 <1.0 <1.0 1.5
8/28/2019 <1.0 1280 1.6 60 777 1.5 12.6 <1.0 2320 1.7
9/11/2019 <1.0 <1.0 1.7 75 <1.0 1.2 <1.0 <1.0 9.9 <1.0 <1.0 1.9
9/25/2019 13 194 1.6 132 118 1.9 8.1 <1.0 <1.0 2.3
10/8/2019 6.0 737 2.0 80 <1.0 2.2 10 744 8.00 3.0 492 1.3
10/23/2019 7.0 <1.0 2.3 48 <1.0 1.7 16.4 5.0 <1.0 0.85
11/6/2019 <1.0 11 0.96 177 379 0.99 <1.0 48 8.5 614 1480 0.57
11/20/2019 <1.0 37 1.2 <1.0 35 0.91 5.2 <1.0 36 0.56
12/10/2019 19 <1.0 2.2 38 13 1.4 <1.0 <1.0 5.7 <1.0 <1.0 1.2
12/31/2019 24 2170 1.0 52 1370 0.81 3.1 17 112 0.59
1/13/2020 32 72 3.9 79 56 2.7 15 26 6.3 31 78 3.3
March 2020
Dewberry