NC0003760_Toxicity Memorandum_20210505

DocuSign Envelope ID: 6980DCC5-2E3E-47A8-A7A1-D33BC7D88692
Division of Water Resources
May 5, 2021
MEMORANDUM
To: David May
Water Quality Regional Operations, WaRO
ADS
Through: Cindy A. MooreCH
`
Supervisor, Aquatic Toxicology Branch (ATB)
From: Lorimar S. Henning
Environmental Spec iatrst II, Aquatic Toxicology Branch (ATB)
IA
Subject: Whole effluent toxicity test results
Unifi-Kinston LLC (El Dupont)
NPDES Permit # NC0003760/001
Lenoir County
The aquatic toxicity test using flow -proportional composite samples of effluent discharged from
the Unifi-Kinston LLC (El Dupont) has been completed. Unifi-Kinston LLC (El Dupont) has a
permitted effluent discharge of 3.6 million gallons per day (MGD) entering Neuse River (7Q10 of
283.1 CFS). Whole effluent samples were collected on April 13 and April 15 by facility
representative Jeff White for use in a chronic Ceriodaphnia dubia pass -fail toxicity test. The test
failed. Toxicity test information follows.
Test Type 3-Brood Ceriodaphnia dubia chronic pass -fail
Test Result Fail
Test Concentrations 1.9%
Control Survival 91.7%
Control Mean Reproduction 18.92 neonates
Test Treatment Survival 91.7%
Treatment Mean Reproduction 6.25 neonates
First Sample pH 7.68 SU
First Sample Conductivity 499 micromhos/cm
First Sample Total Residual Chlorine 0.05 mg/L
Second Sample pH 7.36 SU
Second Sample Conductivity 1497 micromhos/cm
Second Sample Total Residual Chlorine 0.16 mg/L
Test results for the above samples indicate that the effluent would be predicted to have water
quality impacts. These samples were split and tested by Meritech, Inc. The chronic
Ceriodaphnia dubia pass/fail test run by Meritech, Inc. resulted in a pass. The Aquatic
Toxicology Branch staff has performed an investigation to identify potential reasons for the
disagreeing results for this split test. Please see investigation report attached. Please contact us
if you have any questions or if further effluent toxicity monitoring is desired. We may be
reached at [phone].
cc: Robbie Bullock (WaRO)

DocuSign Envelope ID: 6980DCC5-2E3E-47A8-A7A1-D33BC7D88692
Attachment: Disagreeing Result Investigation Report
Robert Bullock
943 Washington Square Mall
Washington, NC 27889
Subject: April 14, 2021 Toxicity Test
Unifi-Kinston LLC (El Dupont)
NPDES No. NC0003760/001
Lenoir County
Dear Mr. Bullock,
Thank you for submitting the supporting information requested for the April 14th, 2021
effluent toxicity test for Unifi-Kinston LLC (El Dupont). All relevant information has been
reviewed by the Aquatic Toxicology Branch (ATB) staff. Please see the details of our
analysis below.
Composite samples from Unifi-Kinston LLC (El Dupont)'s effluent were collected on April
13th and April 15th, 2021 for a chronic Ceriodaphnia dubia pass/fail toxicity test. The
composite samples were split between two containers, one designated to perform the
self -monitoring NPDES compliance requirement, which was sent to the commercial lab,
Meritech, Inc. (Meritech); and, the second was sent to our State Laboratory at ATB,
which is only used for Quality Control purposes. The tests performed at each lab lead to
disagreeing results, in where Meritech's test resulted in a pass and ATB's test resulted in
a fail.
To investigate the disagreeing split results obtained from the two tests, documentation
concerning sampling, testing, and lab procedures were examined. There were no
irregularities noted between the chain -of -custody forms submitted. All quality
assurance documentation from both labs was in order. However, the conductivity value
for the 2nd effluent sample measured in both labs showed a percent difference of
101.8% (Meritech's value was 487 micromhos/cm, while ATB's value was 1497
micromhos/cm). The second sample chlorine level also showed some differences in
where Meritech detected a chlorine level of <0.1mg/L, while ATB detected a chlorine
level of 0.16mg/L. Typically, these differences deem these two different samples.
Ms. Lorimar Henning, ATB's staff member, had an email conversation with you
regarding this sample. During this conversation, you have described that the split
process of the samples was performed correctly by Mr. Jeff White and that you witness
the split in both occasions. Unfortunately, at this point, our analysis shows that there

DocuSign Envelope ID: 6980DCC5-2E3E-47A8-A7A1-D33BC7D88692
are some discrepancies between samples, but we have not been able to identify the
cause of these differences. ATB recommends a resample for this facility in the future.
Based on the information described above, the sample submitted for the NPDES
permitted monitoring will be recorded as a pass, so no further action is needed. Please
let us know if you have any questions, or need further assistance.
Sincerely,
DocuSigned by:
C;z ooy H, 4e
`—C ncy A'.c5oore, Supervisor
Aquatic Toxicology Branch
Ec: David May, Regional Water Quality Supervisor
Mike Reed, Meritech, Inc.