CMS Land Company (CMS) had a problem with their groundwater: it was leaching toxic levels of mercury, total dissolved solids (TDS), and pH to Lake Michigan’s Little Traverse Bay from buried cement kiln dust. Wastewater resulting from an initial leachate collection system did not meet National Pollutant Discharge Elimination System (NPDES) permit limits or the City of Petoskey’s pretreatment limits.
ECT designed a pilot study for ultrafiltration treatment of the wastewater. ECT constructed, operated, and collected data from the pilot treatment system for six months. Our team demonstrated to the Michigan Department of Environmental Quality (MDEQ), the U.S. Environmental Protection Agency (EPA), the City of Petoskey, and the public, that the wastewater could be treated to meet NPDES permit limits and the City’s pretreatment limits.
After the study, ECT assisted with negotiations between MDEQ and EPA to develop limits for an NPDES permit to discharge treated wastewater to Lake Michigan. The discharge of treated wastewater to Little Traverse Bay and permit issuance were highly controversial and subject to scrutinized public opinion and regulatory oversight. In December 2010, MDEQ issued an NPDES permit to CMS to discharge treated wastewater to Little Traverse Bay. ECT assisted with a 2011 NPDES permit revision and a groundwater-surface water interface (GSI) mixing zone determination. In 2012, the total dissolved solids (TDS) levels increased in both the collected leachate and the upgradient dilution wells. The increase prompted CMS to truck a portion of the collected leachate for permitted deep well injection to avoid exceeding the NPDES permit limit for acute toxicity.
ECT conducted an acute mixing zone demonstration that consisted of macroinvertebrate studies and effluent plume delineation to project the impact of full discharge of all treated leachate and negotiated with MDEQ permit staff to allow full discharge. MDEQ rejected the initial request, but after further negotiation and a modification of the outfall structure, MDEQ modified the permit. CMS was again able to discharge all treated effluent to Little Traverse Bay while meeting permit limits. ECT continued to delineate the effluent plume monthly as a permit stipulation and assists with permit reissuance and compliance.
In 2016, ECT conducted a mercury uptake study in Little Traverse Bay. The study utilized artificial substrate to measure mercury uptake by mussels and periphyton near the site.