2018 Excellence in Environmental Engineering and Science® Awards Competition Winner

Honor Award - University Research

Southeast Commerce Mine Water Passive Treatment Project

Entrant: Dr. Robert W. Nairn, University of Oklahoma
Engineer in Charge: Russell C. Dutnell, P.E.
Location: Norman, Oklahoma
Media Contact: Robert Knox

Entrant Profile

Robert W. Nairn is a David L. Boren Distinguished Professor and Sam K. Viersen Family Foundation Presidential Professor in the School of Civil Engineering and Environmental Science at the University of Oklahoma (OU), Norman, Oklahoma, USA. He is also the Director of the Center for Restoration of Ecosystems and Watersheds (CREW), Associate Director of the Water Technologies for Emerging Regions (WaTER) Center and Adjunct Professor of Biology. He holds a BS from Juniata College, Huntingdon, Pennsylvania (1989) and a Ph.D. from The Ohio State University (1996), both in Environmental Science. Dr. Nairn teaches both undergraduate and graduate courses in environmental science and engineering. The general areas of research of Dr. Nairn and CREW are watershed biogeochemistry, ecological engineering, ecosystem restoration and wetland science. Specifically, hid research focuses on biogeochemical and ecological processes contributing to ecotoxic metal contaminant retention in mine drainage passive treatment systems, receiving stream ecological recovery, low impact development urban stormwater best management practices, and watershed-scale ecological engineering technologies.

Dr. Nairn's research team has worked extensively in the Arkoma Basin coal fields of Oklahoma and Arkansas, the Tri-State Lead-Zinc Mining District of Oklahoma, Missouri and Kansas (including the Tar Creek Superfund Site) and in the Bolivian Andes near Cerro Rico de Potosi. He has published 115 refereed journal articles, book chapters and conference proceedings papers; directed 61 funded research projects for $23 million; advised six post-doctoral researchers, visiting scholars and research scientists, 48 graduate and 65 undergraduate research students; provided over 300 professional presentations and taught numerous short courses and workshops.

Project Description

The Tri-State Mining District (TSMD) was a major producer of lead and zinc concentrates in the 19th and 20th centuries. Upon cessation of underground mining operations, mine voids filled with groundwater and several dozen artesian discharges of metals-contaminated waters began flowing in late 1979. The U.S. Environmental Protection Agency identified four TSMD-related Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund) sites in Oklahoma, Kansas, and Missouri (Figure 1). The Oklahoma portion of the Superfund site includes 100 hectares of disturbed land, 300 million tons of mine waste (chat), 325 hectares of tailings ponds, 400 open mine shafts, 600 exploratory boreholes and elevated risks of land subsidence. In addition, the underground mine workings are filled with 95 million cubic meters of contaminated mine water which flows at the surface through the boreholes and mine shafts. All of the contaminated mine water eventually flows into and devastates the water quality of Tar Creek (Figures 2, 3, 4).

The complexity of the overall problem is multifaceted. The Oklahoma portion was mined from 1891 to 1972 producing 12 million tons of lead and zinc. The extensive underground mines were at various depths with ceilings as highs as 30 m (Figures 6). Only approximately 5% of the mined ore was separated into usable material which resulted in significant quantities of waste materials in tailings piles and ponds.

Over the spring of 2017, Dr. Robert W. Nairn and his research group (Center for the Restoration of Ecosystems and Watersheds – CREW) at the University of Oklahoma (OU) were charged with developing an ecologically engineered system to address the upwelling mine water at the Southeast Commerce (Oklahoma) Site. Development of the Southeast Commerce passive treatment system (PTS) required an in-depth understanding of the surface water hydrology (recharge) and hydraulics of the underground mine workings. Knowledge of the site geology and the host rocks contributing constituents to the mine water was essential to understanding the chemistry of the upwelling mine waters. Most critical was a detailed understanding of the unique aqueous geochemistry of the mine water (i.e., net alkaline waters with significant mineral acidity) and how that chemistry could be manipulated to precipitate and settle out the metals. Dr. Nairn and CREW developed this vital knowledge base from two decades of field and laboratory research throughout the Tar Creek Superfund site.

There were site specific design challenges that required innovative solutions. The most critical design challenge was developing a system to collect the upwelling mine water captured in an existing subsurface French drain (with no as-built design drawings) and channeling the flow through riser pipes in order to take advantage of the "modest" artesian head from the mine workings. Even with the artesian head, the primary impoundment basin had to be excavated and the process units constructed below grade. This design feature allowed CREW to retain all existing infrastructure. The final downstream final polishing unit was connected using open channels and an oversized (low headloss) final effluent pipe (Figures 7, 8, 9).

Another design challenge was site proximity to the local public schools which could be subjected to nuisance odors from sulfate reducing treatment processes. The solution was to incorporate a solar-powered hydrogen sulfide removal system utilizing custom-made activated charcoal media (Figure 10).

Another daunting challenge for CREW was the limited available land area (2.5 acres) and the existing onsite stormwater detention pond which could not be impacted. CREW fit the entire treatment system into the 2.5acres by utilizing shared berms and baffle curtains and Z-pile reinforced berms for directing process flow. This innovative "sequential flow directing" feature allowed us to maximize the serpentine flow path length (i.e., the hydraulic retention time), while maintaining a single water surface for the three main process units.

The final system design included four sequential process units (Oxidation Pond, Surface Flow Wetland, Vertical Flow Bio Reactor -VFBR, Final Polishing Unit – Figure 11) utilizing targeted contaminant removal processes (oxidation, reduction, sorption, and precipitation). The treatment system is totally passive in that all energy is derived from gravity or solar powered sources. The system requires no added chemicals other than the original load of mushroom compost in the VFBRs.

The Southeast Commerce PTS now treats 380 L/min of low quality mine water. The system produces effluents which are circumneutral pH, net alkaline, and contain concentrations of the ecotoxic metals meeting receiving water body in-stream criteria. The habitat of the receiving stream has recovered (Figure 12) as evidenced by the return of native wildlife (Figure 13) and 14 different fish species (Figure 14). In addition, beavers have attempted to move in and construct dams that would have inundated the treatment system. The beavers were relocated using an innovative" beaver deceiver" system (Figure 15).

As noted in the attached testimonial letter from the Oklahoma Department of Environmental Quality, "the passive treatment system (PTS) is removing heavy metals from the water" and "we are seeing recovery of fish species in the streams directly downstream of our project area" The Project Manage also noted "the technical quality of the work was outstanding" and "OU's dedication and perseverance on this project demonstrates the overall quality of the service provided."

The Southeast Commerce site also presented significant ethno-social-political complexities. First, approximately 25% of the population of northeastern Oklahoma is Native American. Since 1999, Dr. Nairn and his CREW researchers have participated in watershed assessment and management efforts with the Miami, Ottawa, Wyandotte, Shawnee, Eastern Shawnee, Modoc, Quapaw, Peoria and Seneca-Cayuga tribes through the Grand Lake Watershed Council (Figure 16). The Southeast Commerce PTS is actually constructed on land originally ceded to the Quapaw tribe.

The landscape of northeast Oklahoma is predominantly rural and there is an elevated poverty rate for that portion of the state. Regardless of the environmental pollution, the residents of Ottawa County are extremely proud of their mining legacy and there is a pervasive "sense of place" within the community. The local community is justifiably proud of the SE Commerce Mine Water Passive Treatment System.

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Figure 1: Photograph of Historical Map Showing Superfund Sites Superimposed on Mining Areas in the Tri-State Mining District	Figure 2: Aerial Photograph of Portion of Tar Creek Superfund Site with Textboxes Delineating the Various Environmental Problems Encountered

Figure 3: Collage of Six Pictures Showing Discrete Environmental Concerns from Throughout the Tar Creek Superfund Site	Figure 4: Photograph of Mine Water Upwelling through an Abandoned Exploratory Borehole (note that the bubbles are due to degassing of mine water supersaturated with CO₂)

Figure 5: Photograph of Iron Laden Mine Water and Waste Chat in Stream Bed of Unnamed Tributary Flowing Into Tar Creek	Figure 6: Photograph of Tall Underground Mining Cavern with Lode Cars and Rail Lines (note the miner suspended by rope in the yellow circle).

Figure 7: Photograph of Hanging Impermeable Baffles Used to Create Serpentine Flow Path through Oxidation Pond	Figure 8: Photograph of Floatmaster Aerators in Third Leg of Oxidation Pond (note the change in color of water from Figure 8).

Figure 9: Photograph of Z-Piles Used to Provide Stability to Narrow Flow Direction Berms in Vertical Flow Bioreactors (note the rust colored, iron laden water in the oxidation pond in background).	Figure 10: Photograph of Flow Control Structure With Pipe Leading to Shed Housing Granular Activated Carbon Air Stripping Units to Control Air Emissions of Hydrogen Sulfide (solar power panels used to provide power to blowing aerators; rip rap is emergency overflow structure).

Figure 11: Aerial Photograph of Completed Southeast Commerce Passive Treatment System	Figure 12: Photograph of Receiving Stream Downstream of System Effluent

Figure 13: Wildlife Photograph of Bobcat with Dinner Crossing Bridge at Downstream Flow Measuring Weir	Figure 14: Collage of Pictures Showing Ten of Fourteen Fish Species Documented in Receiving Stream Downstream of System Effluent

Figure 15: Photograph of "Beaver Deceiver" System Used to Prevent Beavers from Building Dams That Would Inundate Final Polishing Unit of Treatment System	Figure 16: Map Showing Tribal Jurisdictions in the Tar Creek Superfund Site in Northeast Oklahoma