[UEL] Eliminating Deep Seepage from a Tailings Storage Facility

OVERVIEW

United States Steel Corporation (U. S. Steel), the Seeker for this Innocentive Challenge, is seeking novel, passive approaches that eliminate or significantly reduce deep seepage from the Tailings Storage Facility (TSF) at the U.S. Steel Minntac facility.

Minntac is a legacy facility where iron-bearing rock called taconite is mined, extracted, and processed into iron ore pellets which are then used in steelmaking. Tailings produced from ore processing are deposited in the TSF. Sulfates and other constituents generated through this process are retained within a closed-loop water system at the site, held in a tailings basin and managed at the TSF. However, water from the basin is currently leaving the containment infrastructure and potentially seeping into regional groundwater.

Solutions must address deep seepage that can potentially daylight (restore from underground) to surface waters. Future environmental regulations will likely classify current deep seepage as functionally equivalent to surface water discharge (with new limits on parameters such as sulfate, total dissolved solids (TDS), conductivity, etc.).

This Prize Challenge invites innovators, research teams, and leading organizations to propose new strategies, techniques, or systems that eliminate or significantly reduce deep seepage from the TSF at the U. S. Steel Minntac facility in Mountain Iron, Minnesota. Solvers are invited to propose novel materials, in-situ treatments, geotechnical barriers, or multi-system approaches that avoid high capital costs or long construction timelines.

A winning submission will demonstrate a clear path towards a passive, cost-effective, and permanent solution, and will be evaluated against its practical feasibility.

Your IP Rights are protected in this Prize Challenge; U.S. Steel must pay you an award to obtain them.

There is a guaranteed award pool of $15,000 available for proposed solutions that meet or partially meet the must have Solution Requirements. The best solution(s) have the opportunity to win awards from $5,000 to $15,000 for meeting enough of these requirements criteria, with their supporting feasibility and rationale. The Challenge requires a written proposal to be submitted and Awards will be contingent upon the theoretical evaluation of your proposal by U.S. Steel. To receive an Award, Solvers are required to grant non-exclusive license rights to the Intellectual Property (IP) in their proposed solution. Solvers will retain all rights to any proposal not Awarded and there is no assignment.

Solvers may:

• Submit ideas of their own
• Submit third-party information that they have the right to use and further, the authority to convey to U.S. Steel this right with the right to use and develop derivative works
• Submit information considered in the public domain without any limitations on use

U.S. Steel is willing to consider a collaboration agreement if non-exclusive IP rights cannot be transferred by a Solver that is an organization owning the IP rights in their proposed solution.

Submissions to this Challenge must be received by 11:59 PM (US Eastern Time) on February 23rd, 2026.

Please review the later Participation Guidance section before submitting a proposal.

- Login or register your interest to start solving! -

ABOUT THE SEEKER & ELIGIBILITY

Founded in 1901, United States Steel Corporation is a leading steel producer. With an unwavering focus on safety, the Company’s customer-centric Best for All^® strategy is advancing a more secure, sustainable future for U.S. Steel and its stakeholders.

With a renewed emphasis on innovation, U.S. Steel serves the automotive, construction, appliance, energy, containers, and packaging industries with high value-added steel products such as U.S. Steel’s proprietary XG3^® advanced high-strength steel. The Company also maintains competitively advantaged iron ore production and has an annual raw steelmaking capability of 25.4 million net tons.

U.S. Steel is headquartered in Pittsburgh, Pennsylvania, with world-class operations across the United States and in Central Europe. For more information, please visit www.ussteel.com

THE CHALLENGE

Background

At U.S. Steel Minntac, process waters containing sulfate, TDS, conductivity and other pollutants originates from the oxidation of sulfide-bearing minerals during taconite ore processing. The process waters are retained within a closed-loop water system, held inside the Tailings Storage Facility (TSF) or tailings basin at the north side of the plant. The tailings basin contains approximately 13 billion gallons of process water, and spans roughly 8,000 acres.

Figure: an aerial view of the Tailings Storage Facility (TSF) at U.S. Steel Minntac, located in Northern Minnesota close to the city of Virginia, MN. The yellow border indicates the borders of the TSF. The water at the North and North East sides of the TSF are the tailings basin.

While surface seepage (approximately 0 to 12 feet deep) from the basin is managed via an east and west return system, the deeper seepage water into the surrounding area remains largely uncontrolled – with water potentially seeping through fractured rocks around and beneath the edges of the basin. Towards the surface, process water is still passing through coarse (like sand and gravel) and fine (e.g. siltier material) tailing barriers or dams into the native soil, eventually potentially reaching the regional groundwater. There is no engineered liner beneath the TSF and, at deeper points, the basin floor is very close to bedrock which is enabling underground seepage.

Deep seepage from the basin discharges eastward to the Sand River and westward to the Dark River. Upcoming regulations may classify these seepage flows as being functionally equivalent to surface discharges – meaning sulfate limits (as well as other limits) will be triggered at compliance points, including groundwater monitoring wells and surrounding surface waters.

A current mitigation focus has included a proposed cutoff wall to line the north eastern perimeter of the basin, 3 miles long and 3 feet thick. This would run from the surface all the way down to the floor and notched into the bedrock layer. The cutoff wall depth could reach ~150 feet, but with an average of about 50 feet deep into the basin. This feat of engineering would likely have large cost and timeline implications, as well as not addressing issues on the west side of the basin.

U. S. Steel is therefore open to alternative approaches that offer lower cost, reduced environmental disturbance, overall facility compliance or shorter construction timelines than the currently proposed cutoff wall. While solutions that can be implemented within 2–3 construction seasons are desirable, U. S. Steel will also consider longer-term approaches if they offer significant advantages in cost, performance, or sustainability.

The Challenge

Solvers are asked to propose a passive solution that eliminates or significantly reduces deep seepage from the Tailings Storage Facility (TSF) at U. S. Steel Minntac.

Solutions should address the geological complexity of the TSF site, preserve the integrity and function of the collection return system for surface water and existing earthen dams and dikes, and ideally provide a lower-cost, shorter timeline alternative to a full cutoff wall.

Concepts must be suitable for permanent compliance at the site, given that tailings containment and water quality compliance limits will be required indefinitely regardless if the mine is open or even still operated by U. S. Steel.

Key environmental considerations for any solution include:

• The subsurface geology of the basin includes fractured bedrock, which contributes to both the scale of seepage, its unpredictable pathways, and the difficulty in initial mitigation
• The TSF’s structure, while unlined, consists of various dams and dikes at the surface, and walls of fine tailings cores and coarse tailing barriers
• The scale of the facility – the TSF covers 8,000 acres and the basin itself contains an estimated 13 billion gallons of water

Solvers are asked to concentrate their solutions on addressing deep seepage at the basin. Surface seepage at the facility is currently managed by a collection return system.

SOLUTION REQUIREMENTS

Innovation and creative thinking to meet the requirements are welcomed, providing solutions display a strong technical feasibility and evidence-based justification.

Solutions from Technology Readiness Level (TRL) 2-5 are preferred, spanning ideation-level ideas for what can be done to proof-of-concept solutions that use evidence-backed examples to demonstrate the feasibility of your approach.

Any successful solution to the Challenge will need to satisfy the following must have requirements:

1. Eliminate or significantly reduce deep seepage of water from the TSF at the U.S. Steel Minntac facility to the surrounding groundwater
   • Solvers should propose functional, effective, and economically viable approaches
   • Any approach or solution must not impact the function of the TSF’s collection return system for surface seepage or the stability of the basin’s dam and dikes infrastructure
   • Additionally, U.S. Steel would be amenable to methods/solutions/approaches that achieve reduction of deep seepage while also addressing sulfate concentrations within the basin water or groundwater at compliance sample locations (such that the level does not exceed permit concentration levels)
2. Prevent future environmental liabilities, secondary contamination/seepage pathways, or future legacy issues
3. Minimized capital and operating costs of solution – U. S. Steel is looking for innovative approaches that can achieve the desired outcome while balancing operational and set-up costs. Please detail all costs in your submission and be communicative of potential timelines.
4. Ability to operate in cold temperatures – with lows of −60 °F or −51.1 °C recorded in Northern Minnesota winters in extreme cases - please state any area of your solution that may be negatively impacted by cold temperatures.

Additionally, U. S. Steel would be particularly interested in solutions that display the following nice-to-have criteria:

1. Increased networked effectiveness of the facility - in addressing the elimination or reduction of deep seepage at Minntac, Solvers are encouraged to consider the wider operations of the plant and how to maintain, as far as possible, the ordinary operations involved in storage of tailings and process water. Solutions that also improve the collection return of surficial seepage will be well received.
2. Minimized ecological disturbance during implementation.

Things to Avoid/Out of Scope:

Solutions that require full or partial basin dewatering are likely infeasible, and plans for complete basin lining have likely already been scoped and are covered by the plan for a potential cutoff wall, and should therefore be avoided.
 

Solutions with Technology Readiness Levels (TRLs) 2-5 are invited. 

This Prize Challenge has the following features:

1. Your IP Rights are protected; U.S. Steel must pay you an award to obtain them.
2. There is a guaranteed award pool of $15,000 available for proposed solutions that meet or partially meet the must have Solution Requirements. The best solution(s) have the opportunity to win awards from $5,000 to $15,000 for meeting enough of these requirements criteria, with their supporting feasibility and rationale.
3. The Challenge requires a written proposal to be submitted and Awards will be contingent upon the theoretical evaluation of your proposal by U.S. Steel.
4. To receive an Award, Solvers are required to grant non-exclusive license rights to the Intellectual Property (IP) in their proposed solution. Solvers will retain all rights to any proposal not Awarded and there is no assignment.
5. The award distribution will be determined after the theoretical evaluation of the proposal by U.S. Steel against the Solution Requirements.
6. U.S. Steel is willing to consider a collaboration agreement if non-exclusive IP rights cannot be transferred by a Solver that is an organization owning the IP rights in their proposed solution.
7. U.S. Steel may also issue “Honorable Mention” recognitions for notable submissions that are not selected for monetary awards.

YOUR SUBMISSION

Please login and register your interest, to complete the submission form.

The submitted proposals must be written in English and can include:

1. Participation type – you will first be asked to inform us how you are participating in this challenge, as a Solver (Individual) or Solver (Organization).
2. Solution Level - the Technology Readiness Level (TRL) of your solution.
3. Problem & Opportunity - highlight the innovation in your approach to the Problem, its point of difference, and the specific advantages/benefits this brings (up to 500 words).
4. Solution Overview - detail the features of your solution and how they address the SOLUTION REQUIREMENTS, particularly with regards to eliminating or reducing deep seepage at U.S. Steel Minntac, preventing future environmental liabilities, minimized capital and operating costs of the solution, and ability to handle Northern Minnesota winters (500 words, there is space to add more in the summary field, and attach supporting data, diagrams, etc).
5. Experience - Expertise, use cases and skills you or your organization have in relation to your proposed solution (up to 500 words).
6. Solution Risks - any risks you see with your solution and how you would plan for this (up to 500 words).
7. Timeline, capability and costs - describe what you think is required to deliver the solution, estimated time and cost (up to 500 words).
8. Online References - provide links to any publications, articles or press releases of relevance (up to 500 words).

PARTICIPATION GUIDANCE

1. Submission Close Date: Submissions to this Challenge must be received by 11:59 PM (US Eastern Time) on February 23rd, 2026.
2. Late submissions: Late submissions will not be considered.
3. Multiple submissions, 3 Maximum: In case of multiple submissions by the same Solver, only 3 submissions – the final 3 submitted – will be considered. Any other submissions will be deleted prior to evaluation.
4. Submission form and attachments: Your submission will be evaluated by the evaluation team first reviewing the information and content you have submitted at the submission form, with attachments used as additional context to your form submission. Submissions relying solely on attachments will receive less attention from the evaluation team.
5. Evaluation notification steps: After the Challenge submission close date, U.S. Steel will review and select the winning ideas/solutions according to the timeline in the Challenge header. Everyone who submits a proposal will be notified about the status of their submissions.
6. Use of AI: Please note that any submissions produced solely with generative AI are not of interest.
7. Learn more: Find out more about participation in Innocentive Challenges.