HomeMy WebLinkAboutNC0026042_Toxicity result_20220304DocuSign Envelope ID: 50F12C32-1457-423C-AE94-DF51080BA8D6
Division of Water Resources
March 3, 2022
MEMORANDUM
To: David May
Water Quality Regional Operations, WaRO
Through: Cindy A. Moor
Supervisor, Aquatic 'cology Branch (ATB)
From: Lorimar S. Hennin IA
Environmental Specialist II, Aquatic Toxicology Branch (ATB)
Subject: Whole effluent toxicity test results
Robersonville WWTP
NPDES Permit # NC0026042/001
Martin County
The aquatic toxicity test using constant time/constant volume composite samples of effluent
discharged from the Robersonville WWTP has been completed. Robersonville WWTP has a
permitted effluent discharge of 1.8 million gallons per day (MGD) entering Flat Swamp Creek
(7010 of 0.27 CFS). Whole effluent samples were collected on February 8 and February 10 by
representative Charles Hyman 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 27.58 neonates
Test Treatment Survival 100%
Treatment Mean Reproduction 33.0 neonates
First Sample pH 7.94 SU
First Sample Conductivity 595 micromhos/cm
First Sample Total Residual Chlorine <0.2 mg/L
Second Sample pH 7.81 SU
Second Sample Conductivity 390 micromhos/cm
Second Sample Total Residual Chlorine <0.2 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 Meritech, Inc. The chronic
Ceriodaphnia dubia pass/fail test run by Meritech, Inc. 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 cindy.a.moore@ncdenr.gov and lorimar.henning@ncdenr.gov.
Basin: Tar -Pamlico
cc: Robbie Bullock (WaRO)