Aqua Survey conducts Toxicity Identification Evaluation (TIE) studies for wastewater facilities or consultants to try to characterize or identify toxic constituents in a wastewater, soil or sediment. Our staff has been nationally recognized for its expertise in this field for over 20 years. There are many NPDES permits that have acute and/or chronic toxicity limits. If these limits are exceeded, the municipal or industrial waste treatment plant must remove or reduce the toxicity to an acceptable level.

One mechanism to do so is to use the TIE approach. This TIE approach uses EPA methods to track toxicity in a three-phased program in which toxicity is first characterized (Phase I), then identified (Phase II) and finally confirmed (Phase III). These TIE methods can be used on freshwater or marine discharges. In Phase I of a TIE program, effluent samples are manipulated by relatively simple physical or chemical processes (i.e., aeration, filtration, pH manipulation, use of EDTA, thiosulfate and C-18 solid phase extraction columns). Toxicity is compartmentalized into certain types of compounds (i.e., cationic metals, volatile compounds, nonpolar organic compounds, acids and bases, etc.).

No analytical verification is required in Phase I testing. In Phase II, toxicants are identified by chemical analysis in each compartment defined by Phase I as being toxic. In Phase III of a TIE program, toxicity is confirmed by a “weight of evidence” approach. Once the causative toxicant(s) is (are) determined by the TIE methodology, an engineering solution can be developed to remove or reduce toxicity to an acceptable level.