NC0047597_Toxicity ATB Split Sample Results_20240730

Docusign Envelope ID: 3E7CE48A-1C413-4918-81FC-A85F940BD3A2
o...N,..« .,.D; Q DWR
Division of Wafter Resources
July 30, 2024
MEMORANDUM
To: Michael Hall
Water Quality Regional Operations, RRO
Through: Cindy A. Moore
Supervisor, Aquatic Toxicology Branch (ATB)
DS
From: Madison E. Myers
Environmental Specialist II, Aquatic Toxicology Branch (ATB)
Subject: Whole effluent toxicity test results
South Durham WRF
NPDES Permit # NC0047597/001
Durham County
The aquatic toxicity test using flow -proportional composite samples of effluent discharged from
the South Durham WRF has been completed. South Durham WRF has a permitted effluent
discharge of 20 million gallons per day (MGD) entering New Hope Creek (7Q10 of 0.15 CFS).
Whole effluent samples were collected on July 16 and July 18 by Jesse Barnes and facility
representative Charles Cocker for use in a chronic Ceriodaphnia dubia pass -fail toxicity test. The
test passed. Toxicity test information follows.
Test Type 3-Brood Ceriodaphnia dubia chronic pass -fail
Test Result
Pass
Test Concentrations
90%
Control Survival
100%
Control Mean Reproduction
18.1 neonates
Test Treatment Survival
100%
Treatment Mean Reproduction
24.6 neonates
First Sample pH
6.78 SU
First Sample Conductivity
526 micromhos/cm
First Sample Total Residual Chlorine
<0.1 mg/L
Second Sample pH
6.84 SU
Second Sample Conductivity
579 micromhos/cm
Second Sample Total Residual Chlorine
<0.1 mg/L
Test results for the above samples indicate that the effluent would not be predicted to have
water quality impacts. These samples were split and tested by ETT. The chronic Ceriodaphnia
dubia pass/fail test run by ETT resulted in a pass. Please contact us if you have any questions or
if further effluent toxicity monitoring is desired. We may be reached at
[e-mail] and [e-mail].
Basin: Cape Fear
cc: Jesse Barnes (RRO)