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Monitoring And Safety: Mile Post 7 Expansion

Last month, the Northshore Journal published an article that covered some of the controversial histo­ry surrounding Reserve Mining’s practice of discharging mining waste directly into Lake Superior at Silver Bay. That practice con­tinued from 1956, when iron ore processing began in Silver Bay, until 1980, when Reserve Mining was forced by court order to devel­op a way to deposit waste material on land. The purpose of the article was to give an accurate account of the impacts that Reserve Mining’s practice had on Lake Superior and the communities surrounding Silver Bay and as far south as Duluth. The legal battles that ensued over those practices resulted in the construc­tion of the Mile Post 7 tailings dam. Recent plans to expand the tailings dam have understandably reignited concern over the possible effects that expansion may pose to the en­vironment and the people who live in proximity to Mile Post 7.

Both Cleveland Cliffs and North­shore Mining were contacted in the hope that company officials would respond to some of the con­cerns and questions that people have about the plan to expand Mile Post 7. That plan apparently relies on an environmental review that is 40 years old and is itself somewhat controversial. As of this writing, no official from Cleveland Cliffs or Northshore Mining has responded to requests for information. In the absence of a response from corpo­rate officials, I have turned to the Department of Natural Resources (DNR) and the Minnesota Pollution Control Agency (MCPA), seeking answers to questions about mon­itoring and the safety of the site. In next week’s issue of the Northshore Journal, the thoughts, opinions and concerns of area residents who are most likely to be impacted by the Mile Post 7 expansion will be presented.

The following questions were posed to the DNR Office of Communica­tions and Outreach. Their answers here are rendered verbatim.

What is the current volume of tail­ings debris stored at Mile Post 7 and what is the projected volume that expansion will allow?

“The volume of existing tailings stored at Mile Post 7 is 119,118,000 long tons of material”. The DNR asserts that the “proposed project at Mile Post 7 is not an expansion of the tailings basin, as the proposed dam extension will not increase the available tailings storage of the facility. Rather, using the remain­ing capacity of the tailings basin requires construction of the dams based on an ongoing assessment of conditions at the facility”. This will allow for the storage of an estimated 753,023,000 long tons of tailings”.

One may find the above wording confusing. Presumably, “not in­creasing the available tailings stor­age at the facility refers to the sur­face area that currently comprises the Mile Post 7 site. That surface area will apparently not be expand­ed. It seems that dam extensions, however, (raising the dam height from 1,240 feet to 1,365 feet) will in­crease the volume of tailings debris stored at Mile Post 7.

How long will the Mile Post 7 site be actively used to collect tailings waste?

“The length of time during which additional tailings may be added to the Mile Post 7 tailings basin is a function of the overall length of a Permit to Mine. The permit term for this facility will be established during the required process to amend the current Permit to Mine. The Permit to Mine currently esti­mates that operations, reclamation, and closure will be complete by 2078. This estimate includes ap­proximately 10 years for reclama­tion beyond active mining, process­ing, and waste disposal”.

Mile Post 7 is a toxic waste site. Is that toxicity permanent or does it diminish over time?

“Mile Post 7 is a tailings dispos­al facility and is not considered a toxic waste site under state or federal law. Tailings are rough­ly composed of sand-to-talc sized particles of left-over ground rock from the processing of mined ore. The Mile Post 7 basin is required to comply with all state and federal laws, as well as permit conditions regulating management of miner­al fibers, water quality, air quality, operations, reclamation, and clo­sure. Any discharges or emissions from the tailings basin must meet all laws and permit requirements during the active life of the facility and in closure”.

Can you explain some of the design, monitoring and safety measures that reduce the risk of possible dam failure?

(The) “Mile Post 7 tailings dams are some of the most closely reg­ulated dams in the state, meeting all applicable factors of safety and state dam safety laws.

Tailings dams are designed with careful consideration of all po­tential failure modes, including slope failure or overtopping. En­gineers investigate the underlying area and dam construction mate­rials through geotechnical investi­gations to determine the material strengths. Those material strengths are entered into computer stability models, along with conservative assumptions for conditions such as a very high pond level, to test the stability of the proposed dam. Fac­tors of Safety for various conditions (i.e., liquefaction, seismic activity, weather events, etc.) under current and future conditions are deter­mined and compared against in­dustry standards. If a dam does not meet or exceed these requirements, the project proposer’s engineer of record would need to identify what measures should be applied to in­crease stability and bring the fa­cility to the appropriate Factors of Safety. If (the) DNR were to deter­mine that the design of a dam was unsafe (i.e., did not meet the Fac­tors of Safety), the design would not be approved, and the dam could not be constructed.

The Mile Post 7 dams are monitored in a variety of ways. Water levels in the tailings basin are monitored to ensure there is adequate storage for an extreme flood. Instrumentation in the ground, such as piezometers, measures groundwater conditions in, under, and around the dams. In­clinometers and settlement plates measure movement and settlement of the dam embankments. On-site staff conduct routine inspections, the engineer of record conducts multi-day annual inspections, and DNR dam safety engineers conduct annual inspections of the dams. These inspections include a review of these records and a visual inspection to determine if there is any condi­tion that could lead to dam failure. Any findings are documented and required to be addressed.

The Mile Post 7 dams include a number of design and operational components to help ensure the safe­ty of the dam. The pond level is maintained at a low enough level to provide capacity to safely store the water associated with an ex­treme flood event. An emergency action plan includes a dam breach analysis to understand the impacts of a hypothetical breach of the dam. The emergency action plan also identifies specific steps to be tak­en in the unlikely event of a breach of the dam, such as notifications to the public and procedures for evacuation and road closures. The plan identifies the emergency man­agement personnel responsible for executing various elements of the plan”.

The following questions were posed to the Communications Manager for the Minnesota Pollution Control Agency (MPCA). The answers are rendered verbatim.

How often are surrounding streams and rivers monitored for tailings seepage in and around Mile Post 7?

“The water permit (also called the National Pollutant Discharge Elim­ination System (NPDES) permit) identifies locations and frequency of monitoring upstream and down­stream of the facility. The permit does require fluoride to be sampled twice per month”.

What seepage level is considered “acceptable” and has this level ever been detected or exceeded at Mile Post 7?

“Seepage is collected and pumped back to the tailings basin. The NP­DES water permit discusses how seepage is managed as well as how water is collected and treated. Seep­age is not allowed to be directly dis­charged from the seepage collection system. There have been historical exceedances of fluoride in the treat­ment system for the tailings basin. Future permit actions will address this issue”.

Northshore Mining is obviously important to Silver Bay and sur­rounding communities and the mining and processing of iron ore are important on both a national and global level. While the information obtained from the DNR and MPCA indicate some of the design, moni­toring and safety precautions being taken at Mile Post 7, it continues to be appropriate for the public to express concern, ask questions and receive clear answers from compa­ny officials. Whether one supports the Mile Post 7 expansion or not, trans­parency leads to understanding and trust, which is what citizens need and deserve.

Rick Evans
Rick Evans
My wife, Marsha Kinzer (a proud DEHS Greyhound, class of ‘77) introduced me to the North Shore on vacation in 2012. It became our regular escape when the stress of our careers in education became overwhelming, and it didn’t take me long to fall in love with the breathtaking scenery, the nice people, and “salad” containing Jell-o and marshmallows. So you can either blame or thank my loving wife for my being here, because when we needed to choose a retirement hometown, Marsha advocated hard for her beloved Duluth, and here we are, six months later. Yes, this will be my first northern Minnesota winter. Yes, I welcome thoughts and prayers. Government, public policy, and social justice weighed heavily in the curriculums I taught at the high school level over a thirty-eight year career. In addition, we were a laboratory school focused on critical thinking in conjunction with technical and scientific writing. So when I found myself adrift on the great ocean of retirement and spied a raft, I jumped at the chance to take up what I’d left behind…minus the bad teachers’ lounge coffee. My position at the NSJ allows me to combine my passions for government and writing, and it’s helping me to feel less out of touch in new surroundings. When I’m not being “Cubby” (Marsha’s favorite new nickname for this green reporter) I enjoy pointing at eagles and saying, “Look, honey. There’s an eagle.” I’ve had an active side hustle as a professional musician for almost as many years as Charlie Parr. As a guitarist/singer/songwriter, I graced the stages of clubs and festivals around southern Wisconsin, including an appearance on A Prairie Home Companion. Should I even mention A Prairie Home Companion, or am I the only one here old enough to remember what that is? Look! An eagle!
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