A Story about Copper: Water vs. Wastewater, Part 3

Last June (2014), we expanded on an earlier newsletter article (June 2013) regarding the extremely low limits for copper on many wastewater plant effluents. For more than five years, we have been working with IDNR staff to enable the utilization of the Biotic Ligand Model by POTWs with very low copper NPDES limits.

The following article is an update to an ongoing effort to resolve this issue in a manner that both protects the aquatic environment and allows cities to discharge their “used” drinking water to the wastewater treatment plant.

Click on the following links to access Part 1 of this series:

www.foxeng.com/news/story-about-copper-water-vs-wastewater-part-1, and Part 2: https://foxeng.com/news/story-about-copper-water-vs-wastewater-part-2

The BLM utilizes site specific data (alkalinity, dissolved organic carbon, calcium, magnesium, sodium, potassium, chlorides, sulfates, sulfide, and pH), from the receiving stream to model the aquatic toxicity of copper for that stream; EPA endorses this method as a means to determine the aquatic toxicity of copper in the environment. Since most of the copper is tied up in organic matter, it is not bioavailable to aquatic life; thus the additional data usually provides documentation that the copper effluent is less toxic than the default values used for the NPDES.

We cited our earliest BLM project in New Hampton, where they have been the leading proponent of pursuit of this method for utilization. In New Hampton, the copper picked up in the wastewater from copper piping and food will put them in violation of the NPDES limits; you can drink up to 1.3 mg/L of copper, but New Hampton’s effluent must be less than 0.017 mg/L.

Last fall, the IDNR sponsored a stakeholder’s meeting to discuss pursuit of the necessary rule making that would allow POTWs to use the BLM for fine-tuning their NPDES discharge limits. On Wednesday, June 10, the DNR is hosting another “stakeholder meeting to discuss the inclusion of the Biotic Ligand Model in the determination of copper criteria, which allows for site-specific variations in the bioavailability and toxicity of copper. Changes are proposed to allow the flexibility to use the existing copper criteria, or the ability to use the Biotic Ligand Model to generate site-specific criteria based on known data from the site area.” This meeting will be held from 9:30 am to 12:00 noon at the Wallace Building.

Plan to attend!

We encourage anyone who might be interested in this topic to plan on attending; the meeting is being coordinated by Matt Dvorak at IDNR (515-725-8397 or matthew.dvorak@dnr.iowa.gov). Winnie Gleason will be attending this meeting from FOX Engineering; contact her with any questions or comments – before or after the meeting (contact information below).

FOX Engineering stays on the leading edge of regulatory and technical issues related to water and wastewater engineering. We take pride in working closely with our clients and regulatory agencies to help ensure reasonable, thoughtful, and cost-effective solutions to real problems.

Stay tuned – we will provide updates on the challenges of copper and other metals in the coming months.

FOX Engineering is an environmental engineering firm based in Ames, Iowa. We specialize in water and wastewater solutions for our diverse municipal and industrial clients. Our work varies in size and scope and can be found throughout the Midwest and beyond.