NC0079057_Action Plan for Compliance_20200630

n Green Engineering,PLLC 303 Goldsboro Street East • PO Box 609•Wilson, NC 27894
eej_1 Water,Wastewater, Surveying TEL [phone] • FAX 252.243,7489
Engineering Planning,Project Management WWW.GREENENGINEERING.COM
June 30, 2020
Town of Manteo
P.O. Box 246
Manteo,North Carolina 27954
Attention: Mr. James Ayers II
Town Manager RECEIVED
SUBJECT: Action Plan for Compliance of Total Copper JUL 0 9 2020
And Dibromochloromethane Limitations NCDEQIDWRINPDES
NPDES Permit NC0079057
PN: 19-067
Dear Mr. Ayers:
In accordance with the renewal of the Town's NPDES Permit and per the Permit's
Special Condition Section A. (4) related to increased compliance monitoring for Total Copper
and Dibromochloromethane, we offer the following Action Plan in compliance with the Section
A. (4) of the permit.
If you should have any questions regarding the enclosed, please do not hesitate to contact
me.
Respectfully,
E. Leo Green, III., P.E.
TDD
Enclosures: As Stated
W:\MANTE\19067\Office\Action Plan\james ayers-action plan transmittal lie 6-15-20.doc

ACTION PLAN
COMPLIANCE FOR TOTAL COPPER AND DIBROMOCHLOROMETHANE LIMITATIONS
TOWN OF MANTEO, NORTH CAROLINA
NPDES PERMIT NUMBER: NC0079057
PERMITTEE CONTACT PERSON: JAMES AYERS, TOWN MANAGER
During renewal of the Town of Manteo's NPDES Permit, the State of North Carolina Department of
Environmental Quality, Division of Water Resources, added limits for Total Copper and
Dibromochloromethane to the permit. In addition, the Division has provided a schedule of compliance
for total copper and dibromochloromethane limitations in Section A. (4) of the renewed permit.
The schedule provided in the permit is as follows:
1. By July 1, 2020, the Permittee shall submit to the Division of Water Resources an Action Plan, for
Division approval, summarizing the strategy or actions to be taken to achieve compliance with
the Total Copper and Dibromochloromethane limitations listed in Sections A. (1). The plan will
include specific dates for completion or implementation of each action.
2. By July 1, 2021, the Permittee shall submit a report to the Division summarizing actions taken in
accordance with the Action Plan.
3. The Permittee shall achieve compliance with Total Copper and Dibromochloromethane
limitations specified in Section A. (1.) by July 1, 2022.
This Action Plan is being written to address item 1. of this schedule.
The Town of Manteo has contracted with Green Engineering to assist them in the preparation of the action
plan and has provided them with a copy of the draft and final permit.
According to the draft permit(Fact Sheet Template: Version 09Jan2017), the following water quality based
effluent limits(WQBEL)have been established based on a Reasonable Potential Analysis(RPA)conducted
on effluent toxicant data collected between June 2013 and March 2018 and a review of three (3) Effluent
Pollutant Scans that found the Copper and Dibromochloromethane exceeded the allowable discharge
concentration from the limited data set.
1. Copper (Monthly monitoring with limit)
a. Monthly average 3.7 pg/I
b. Daily maximum 5.8 pg/I
2. Dibromochloromethane (Monthly monitoring with limit)
a. Monthly average 21.0 pg/I
b. Daily maximum 21.0 pg/I
After conferring with various NCDEQ staff members, it is believed that the high sample results may be a
result of:
1. High copper levels in the ground water and infiltration of this ground water into the Town's sewer
collection system; and
2. THM formation from chlorine disinfection

To determine if item 1 is the cause of the high level of Total Copper, grab samples were taken in February
2020 at the following locations in the Town's collection system and yielded the following results:
Location Copper
(pg/I)
Sample Station Exeter St. 2
Wingina Lift Station 69
Waterfront Lift Station 36
Burnside Lift Station 49
MH 611D 21
MH 603 26
Except for the sample station on Exeter Street, all samples collected indicated copper levels well over the
permit limit indicating the likelihood that groundwater infiltration into the Town's gravity sewer mains and/or
leaching of copper from potable water service lines is the cause for the elevated copper levels.
To determine if item 2 is the cause of the high level of Dibromochloromethane, samples were taken in
February 2020 at the following WWTP processes; yielding the following results:
Location Dibromochloromethane
(pg/I)
Influent Sampler <4.0
•
Splitter Box <4.0
Clarifier Effluent <1.0
Filter Effluent <1.0
Effluent Sampler 14.2
Beginning July 1, 2019, and per the requirements of the renewed permit, the Town of Manteo began
monthly effluent monitoring for Total Copper and Dibromochloromethane. Below are the results of this
sampling:
Date Copper Dibromochloromethane
(pg/I) (pg/I)
7/1/2019 5 12.2
8/5/2019 10.1
9/3/2019 5 8.7
•
10/7/2019 4 11.5
•
11/4/2019 3.8
12/2/2019 3 8.6
1/6/2020 3 14.6
2/1/20 4 8.2
•
3/1/20 4 10
4/1/20 5 15.5
5/1/20 16.6
Average 4.53 14.7
Results that exceed the new permit limits are shown in

In addition, analysis of the Town's sludge in June 2020 indicated copper levels of 403 mg/kg.
From this preliminary information, it appears that the following is occurring:
1. The WWTP is currently receiving raw wastewater from the collection system with high
concentrations of Total Copper and that the existing treatment processes are doing a very good
job of reducing the Total Copper levels in the treated wastewater. However, these levels are higher
than the newly imposed effluent limits.
2. While Dibromochloromethane levels in the collection system are unknown, the sample results
indicate that WWTP Influent levels of Dibromochloromethane are very low and remain low until
chlorination. Therefore, it appears that all growth of this disinfection byproduct species is caused
by the reaction organic matter in the treated wastewater with chlorine and that except for the
unusually high value of 45.9 pg/I in November 2019, all samples taken this past year were in
compliance with the new effluent limits.
It is also possible that the high concentrations of copper in the sludge; while significantly lower than the
allowable concentration stated in 40 CFR § 503.13, may be returned to the aeration basin in the sludge
decant; thereby, increasing effluent copper limits.
Action Plan:
Item #1: Sample for Total Copper and Dibromochloromethane at the WWTP in the following
locations:
• Influent Sampler
• Splitter Box
• Clarifier Effluent
• Filter Effluent
• Effluent Sampler
Provide split samples for analysis at two (2) separate laboratories.
Target Dates: August 2020 & November 2020
Number of Samples to be taken: 20 (copper) + 20 (dibromochloromethane)
Estimated cost of sampling: (20 x $20) + (20 x $50) = $1,400
Item #2: Sample the six (6) locations in the Town of Manteo's collection system at the same
interval as the WWTP sampling for correlation of the WWTP and collection system
samples.
Provide split samples for analysis at two (2) separate laboratories
Target Dates: August 2020 & November 2020
Number of Samples to be taken: 24 (copper) + 24 (dibromochloromethane)
Estimated cost of sampling: (24 x $20) + (24 x $50) = $1,680
Item #3: Sample digester decant during every decant event during a 6 month period.
Target Dates: August 2020—January 2021

Item #4: Evaluate possible treatment options to lower results within allowable limits.
Prepare cost estimates for collection system rehabilitation if testing results indicate that
ground water is a major contributing factor in high Total Copper levels.
Target Dates: January 2021 — March 2021
Item #5: Pilot test a side-stream ultraviolet disinfection unit to determine THM growth immediately
before and after UV disinfection. Compare against THM growth immediately before and
after chlorine disinfection
Target Date: April 2021 —June 2021
Item #6: Prepare report to DWR summarizing actions taken in accordance with the Action Plan.
Provide recommendations in the report to obtain compliance with the Permit.
Target Dates: March 2021 —June 2021