NC0020354_Staff Report_20010803

Division of Water Quality
August 3, 2001
MEMORANDUM
To: Ken Schuster
Water Quality Supervisor, RRO
Through: Matt Matthews:'��
Supervisor, Aquatic Toxicology Unit
From: Sandy Mort AVA
Quality Assurance Officer, Aquatic Toxicology Unit
Subject: Whole effluent toxicity test results
Pittsboro WWTP
NPDES Permit # NCO020354/001
Chatham County
The aquatic toxicity test using 24-hour composite samples of effluent discharged from Pittsboro
WWTP has been completed. Pittsboro WWTP has an effluent discharge permitted at 0.250
million gallons per day (MGD) entering Robertson Creek (7Q10 of 0.00 CFS). Whole effluent
samples were collected on July 24 and 27 by Kirk Stafford for use in a chronic Ceriodaphnia
dubia pass/fail toxicity test. The test using these samples resulted in a pass. Toxicity test
information follows.
Test Type 3 -Brood Ceriodaphnia dubia pass/fail
Test Concentrations 90% sample
Test Result
Pass
Control Survival
100%
Control Mean Reproduction
27.0 neonates
Test Treatment Survival
100%
Treatment Mean Reproduction
22.8 neonates
First Sample pH
7.37 SU
First Sample Conductivity
608 micromhos/cm
First Sample Total Residual Chlorine
<0.1 mg/4
Second Sample pH
6.94 SU
Second Sample Conductivity
533 micromhos/cm
Second Sample Total Residual Chlorine
<0.1 mg/1
Test results for these samples indicate that the effluent would not be predicted to have water
quality impacts on receiving water. Please contact us if further effluent toxicity monitoring is
desired. We may be reached at [phone].
Basin: CPF04
cc: Central Files
Environmental Sciences Branch Water Quality Section

AUG -9 01,