Nyrstar, a global metal-producing company with more than 150 years of manufacturing history, places high expectations on its operations to conduct business in an environmentally responsible way. So when they acquired zinc mines in Middle and East Tennessee, it was no surprise they prioritized the development of environmental strategies to ensure the mines were compliant with state and federal regulations, as well as meeting the needs of the local communities.
Nyrstar planned to expand a tailings impoundment at their Middle Tennessee Mines operation in Smith County. The U.S. Army Corps of Engineers and the Tennessee Department of Environment and Conservation were requiring stream mitigation to offset the impacts to the headwater streams above the tailings impoundment that would be caused by the expansion. Approximately half of the required mitigation would be performed at the Gordonsville Facility, with the other half performed at the Elmwood Facility. Both the initial mitigation plans and associated 401 and 404 Clean Water Act permits were prepared by another consultant Nyrstar had engaged.
Start of CEC’s and Nyrstar’s Collaboration
CEC’s relationship with Nyrstar began in 2014. At that time, Nyrstar was preparing to implement the initial stage of the mitigation plans that would be performed at the Gordonsville mine. In preparation for implementing the initial stream mitigation, Nyrstar representative Steven Turaski reached out to a colleague at the Tennessee Stream Mitigation Program seeking a recommendation for a consultant to oversee construction of the project.
“We had a permit and mitigation plan in place,” says Turaski. “We wanted to start construction, so I asked who the best firms were for the job. Civil & Environmental Consultants and Greg Babbit’s names were on the list, so we asked them to bid on the work.”
When Babbit, CEC Principal in the Ecological Services Practice, went to the site and reviewed the previously approved plan prior to preparation of a proposal, he identified some alternative concepts that he believed would be more feasible to construct and more likely to achieve Nyrstar’s goals. CEC submitted a proposal for construction of the alternative approach. Nyrstar agreed with the alternative approach, CEC won the work, the project was a success, and that was the beginning of a new client partnership.
Continuing the Relationship
In 2017, Nyrstar selected CEC as its consultant to provide the services needed to implement the mitigation construction at the Elmwood Facility because of CEC’s successful completion of the Gordonville project in 2015. The mitigation at the Elmwood Facility would complete the mitigation needed for the impoundment expansion. The stream restoration project involved the reestablishment of 970 linear feet of stream channel within the footprint of the two ponds (upper and lower ponds) that historically had been used to supply water.
There were two significant unknowns associated with the proposed construction. “One issue was not knowing how much sediment was going to need to be excavated from each of the ponds,” explains Babbit. “It was going to be difficult to predict the potential volume and flow rate of water entering the mitigation area once the ponds were drained. Managing the sediment and the potential water issues were the two big unknowns, and turned out to be the most challenging aspects of the project.”
Pulling Back the Curtain
Construction was planned to be performed in phases that spanned two years. As Babbit anticipated, water management was a considerable part of the construction activities. During the construction the team was faced with hillside springs and continuously flowing water as a result of removing the upper pond. One major spring that was designated as the Main Spring was exposed when the upper pond was removed and was a continuous source of water flowing into the mitigation area.
“Once the ponds were drained, it was like pulling back the curtain,” says Babbit. “We found several springs emerging from the hillside we had to manage.”
The team utilized pumps, pipes and created diversion channels that were later used to create wetland pockets as part of the new ecosystem. Sediment from the ponds was disposed of at a site adjacent to the tailings impoundment by implementing a combination of pumps, excavators and off road dump trucks.
Turaski says the field team’s ability to respond to unpredictability in real-time is part of what makes Nyrstar’s partnership with CEC so valued.
“When choosing a consultant, you need trust that they are thinking in your company’s best interest and making sound decisions, sometimes in the field,” explains Turaski. “That comes from experience. Greg and the CEC team were able to develop a functional solution to overcome the challenges.”
Bringing Work and New Life to the Region
The Middle Tennessee Mines have brought much needed employment opportunities in the region. And thanks to the success of the stream restoration projects habitat was restored. As a result, native aquatic and terrestrial plants and animals are making the area their home again.