Assuring Compliance when your NPDES Permit Limit is Non-Detect

National Pollution Discharge Elimination System (NPDES) permit limits and subsequent pretreatment discharge limits for some parameters are now being set at “Non-Detect” in environmentally sensitive watersheds. Will permit holders be able to demonstrate compliance with a “Non-Detect” limit, especially if challenged by the regulator or a third party? Three internationally recognized definitions for detection and quantification will presented; the Critical Level (LC), the Detection Limit (LD) and the Quantification Limit (LQ). We will explore what “Non-Detect” really means and how you can demonstrate compliance when regulatory limits are set below the limit of quantification. Specific case studies will be used to show how statistically defensible limits of detection and quantification can be established. Accurate detection and quantification limits guarantee the environment is adequately protected while ensuring the permit limit can be measured with confidence.