NC0023973_Compliance_20200303

James R.Flechtner,PE
Executive Director
NM Cape Fear 235 Government Center Drive
Wilmington,NC 28403
Public Utility Authority 910-332-6625
[e-mail]
Stewardship.Sustainability.Service.
February 27, 2019
NC DEQ Division of Water Resources Attn: Danny Smith, Director of the Division of Water Resources D E © I U W E
1617 Mail Service Center
Raleigh, NC 27699-1617 2
MAR - 3 2020
SUBJECT: NPDES Permit NC0023973
McKean Maffitt (Southside) WWTP DIVISION OF WATER RESOURCES
DIRECTOR'S OFFICE
Section A. (9) Schedule of Compliance �� T
Dear Mr. Smith:
The Schedule of Compliance incorporated into the above referenced NPDES Permit requires an
annual update on the actions taken to achieve compliance with the NPDES effluent copper
limits. Staff has continued to analyze increased numbers of effluent samples over this last year
and the results confirm the discharge from the above referenced permit would be routinely
non-compliant once the current discharge limits are imposed. However, the loading to the
river is well below the permitted pollutant loading.
To identify any specific sources or operational correlations, CFPUA began sampling in March
2019 per the Corrective Action Plan (CAP) submitted in February. CFPUA began increased
copper monitoring to bi-monthly on the effluent, combined influent and the five separate
outfall lines that contribute to the combined influent. A summary of the 24-hour composite
copper data for these samples is below:
• Individual influent outfall lines ranged from 0.0128 mg/L to 0.0532 mg/L;
• Combined influent ranged from 0.0151 mg/L to 0.0335 mg/L;
• Effluent ranged from 0.0034 mg/L to 0.0092 mg/L.
A review of this data does not indicate any specific areas of the collection system that are
substantial contributors of copper. The data is variable within these ranges and shows no
correlation between the influent and effluent high and lows, rainfall, nor the peaks in
individual outfall lines. The data shows the effluent discharge would have been in compliance
with the daily maximum limit 11 of 26 sampling events or 42% of the time. For each of the
twelve months reviewed, the facility would have been in violation of the established monthly
average limit. However, the highest effluent concentration discharged over this time period

would only contribute 55% of the permitted pollutant loading to the river based on current
daily and monthly flows when compared to the permitted flow of 12 MGD and the effluent
discharge limits.
It is worth noting, the highest copper level detected during the lead and copper drinking water
monitoring in summer of 2019 was 0.33 mg/L. CFPUA maintains an effective lead and copper
control program which was verified by the sampling results and a consultant hired in 2017.
This level is well within the acceptable drinking water standards but is substantially higher than
the results of the influent to the wastewater treatment plant. This would demonstrate that
residential customers with copper plumbing may contribute to the influent levels of copper at
the wastewater facility.
CFPUA is continuing to sample and review outfall and basin contributors to identify any
outliers or sources that may be monitored and potentially decreased to assist in achieving
compliance. Additionally, Staff is evaluating operational practices to determine if there are in
plant changes that can be made without disrupting other treatment efficiencies. This facility is
a secondary treatment facility with trickling filters and is not designed for maximizing removal
of compounds such as copper.
While sampling, customer, operational and data review continues, it is important to also note
the parallel options for compliance CFPUA has been pursuing. CFPUA has partnered with Tetra
Tech and worked with NCDEQ and EPA to identify options such as the creation of a site-specific
copper criteria via a water effects ratio (WER) and has completed a dilution study. The dilution
study has not provided a route to compliance for CFPUA due to the near field mixing of a side
stream discharge. The results of the dilution study with the current configuration resulted in a
less than 2:1 dilution and would not result in limits that would enable compliance for the
facility. These results have prompted further multi-agency discussions which are ongoing
regarding the potential for a diffuser in the Cape Fear River. CFPUA has an upgrade for this
wastewater treatment facility in the current 10-year capital improvement plan (CIP). The
design and construction of a diffuser is anticipated to cost several million dollars. It will also
take a substantial amount of time to permit and construct in this environmentally sensitive
area that is also a navigational channel for large ships, coast guard and general recreational
activities. Although, CFPUA and Tetra Tech have completed a preliminary model of the
diffuser itself to determine the best depth, angle of discharge, direction of discharge, and size
and numbers of ports for the best mixing of the discharge into the river, there is still much
work to be done to complete such a project. With the plant upgrade and expansion already
included in the 10-year CIP, an effective and efficient option for CFPUA, our rate payers, and
the Lower Cape Fear River may be to extend the compliance schedule in the existing permit to
incorporate the diffuser into the upgrade and permit limits be re-evaluated at that time.
The other parallel option Tetra Tech, CFPUA, NCDEQ, EPA, and various other partners have
been discussing are the protocols for a copper WER in this estuarine environment. Following
several discussions regarding the critical conditions that would be taken into account for
development of a WER and the appropriate species to be used given the estuarine waters,
CFPUA is evaluating whether to invest in conducting these studies given several areas of

uncertainty. NCDEQ and EPA have determined that the US-EPA 1994 Protocol for the
Determination and Use of the Water-Effect Ratios for Metals should be used for this project
not the streamlined version of the protocol. As part of its deliberation, CFPUA is working on
obtaining benthos and aquatic life data from the Lower Cape Fear Program which may be used
to help develop a species recommendation for a WER study that might reduce some
uncertainty in the approach.
CFPUA will continue to characterize the waste streams and work with Tetra Tech, NCDEQ, EPA,
and other stakeholders in the coming months on the parallel options. Staff anticipates the
initial advancement of each of the options mentioned above will provide us the information
required to develop the best plan for achieving compliance for our organization, our
customers and the river. If you have any further concerns, please feel free to contact me at
910-332-6542 or Beth Eckert at 910-332-6646.
Sincerely,
Carel Vandermeyden, P.E.
Assistant Executive Director of Treatment and Engineering
Cape Fear Public Utility Authority
cc: Brianna Young, NCDEQ
David Hill, NCDEQ
Julie Gryb, NCDEQ
Tom Tharrington, NCDEQ—Wilmington Regional Office
James R. Flechtner, Cape Fear Public Utility Authority
Beth Eckert, Cape Fear Public Utility Authority
Matt Hourihan, Cape Fear Public Utility Authority
Steven Styers, Cape Fear Public Utility Authority