GLEC designed and performed a study to provide alternative NPDES numeric limit justifications for a municipal and industrial discharger. Studies were performed to determine the site-specific water effect ratios for cyanide, lead and copper. These studies compared the toxicity threshold of all three metals in the receiving water and in a laboratory water. The resulting Water Effect Ratio (WER) for each metal was compared to the current numeric limitation for each metal and adjusted accordingly. The results of this study were also used jointly with a mixing zone and Wasteload allocation study to further address alternative limitations.
Back to Project Experience