NC0036269_Tox Lab Report_20220222

DocuSign Envelope ID: D5D7B5BB-F107-49B1-876D-72593722ABB2
MEMORANDUM
To:
Through:
From:
Subject:
Division of Water Resources
February 22, 2022
Corey Basinger
Water Quality Pr Regional Supervisor, MRO
Cindy A. Moore CF1
Supervisor, Aquatic '1'oxdgology Branch
Lorimar S. Henning l " tk
Environmental Specialist II, Aquatic Toxicology Branch
Whole effluent toxicity test results
Rocky River WWTP
NPDES Permit # NC0036269/001
Cabarrus County
The aquatic toxicity test using flow -proportional composite samples of effluent discharged from the Rocky River
WWTP has been completed. Rocky River WWTP has a permitted discharge of 26 5 million gallons per day
(MGD) to the Rocky River (7Q10 of 25.2 CFS). Whole effluent samples were collected on February 1 and
February 3 by Roberto Scheller for use in a chronic Ceriodaphnia dubia full multi -concentration toxicity test.
The test using these samples resulted in a pass. Toxicity test information follows.
Test Type
Test Concentrations
Test Result
Control Survival
Control Mean Reproduction
Test Treatment Survival
Treatment Mean Reproduction
First Sample pH
First Sample Conductivity
First Sample Total Residual Chlorine
Second Sample pH
Second Sample Conductivity
Second Sample Total Residual Chlorine
3-Brood Ceriodaphnia dubia chronic multi -concentration
0, 33, 50, 66.5, 83, 100%
ChV >100% (Pass)
100%
34.4 neonates
100% in all test concentrations
37.9 neonates in 33%; 34.2 neonates in 100%
6.52 SU
693 micromhos/cm
<0.20 mg/L
6.64 SU
735 micromhos/cm
<0.20 mg/L
Test results for the above samples indicate that the effluent would not be predicted to have water quality
impacts on receiving water. These samples were split with Environmental Testing Solutions, Inc. (ETS) and
Meritech, Inc. (Meritech). The test conducted by ETS was invalidated due to issues during shipment of the
second sample, which exceeded the required sample holding time. The test conducted by Meritech resulted
in a chronic value (ChV) of 74.3%. Please contact us if you have any questions or if further effluent
toxicity monitoring is desired. We may be reached at [e-mail] or
[e-mail].
Basin: Yadkin -Pee Dee
cc: Roberto Scheller, MRO
Aquatic Toxicology Branch Water Sciences Section