INDUSTRY DAY for Leadville Mine Drainage Tunnel Hydraulic Plug

In accordance with Federal Acquisition Regulation 15.201- Exchanges with Industry Before Receipt of Proposals, the Bureau of Reclamation, Great Plains Region will be holding an Industry Day to discuss the planned construction of a remotely installed hydraulic plug in the Leadville Mine Drainage Tunnel (LMDT) near Leadville, Colorado.ScopeThe scope of the project includes the following: drilling approximately 350 feet through glacial soils and granitic bedrock to intercept a 9-foot wide, 10.5-foot tall inaccessible mine drainage tunnel, drill up to 20 feet below the floor of the tunnel, installation of three new pumping wells capable of up to 750 gpm, construction of a 600 foot long buried pipeline to convey tunnel water to an existing pipeline, mechanical and high pressure water cleaning of the tunnel walls, construction of remotely installed cofferdams to temporarily block off the approximately 1,200 gallon per minute (gpm) flow in the tunnel, placement of a concrete plug between

cofferdams, contact grouting and pressure grouting the plug and construction of a small utility building to house controls and valves for the new pumps. All construction will take place at a prepared drill pad at about 10,330 feet above sea level during three construction seasons.BackgroundThe LMDT is an 11,299-foot long mine drainage tunnel constructed between 1945 and 1956 to drain mine workings surrounding the town of Leadville, Colorado. Since March of 1992, Reclamation has operated a water treatment plant to mitigate heavy metals contained in the mine drainage from the tunnel. The first several thousand feet of the tunnel penetrate alluvial soils and unstable fractured rock before entering competent granite and intersecting historic mine shafts. The tunnel has collapsed in multiple locations in unstable rock and soil downstream of the granite and mine workings preventing access to the flooded upstream portions of the tunnel. Reclamation is designing a remotely installed plug upstream of the collapsed areas to separate the upstream contaminated mine water from clean groundwater that enters the downstream portions of the tunnel and mixes with the mine water before it is received at the water treatment plant. By isolating the mine water from the clean groundwater Reclamation will be able to reduce the volume of water treated thus increasing treatment efficiency and lowering treatment cost.Reclamation has selected a plug location approximately 5,100 feet upstream of the tunnel portal and 350 feet below the ground surface for installation of the remotely placed concrete hydraulic plug. The tunnel at this location consists of an unreinforced horseshoe section 10.5 feet tall and 9 feet wide with steel rail supported on timber ties, steel ventilation, water and air pipelines and up to 2-inches of gunite coating on the walls. The walls are also believed to be coated in up to 3 feet of iron hydroxide precipitate. The tunnel contains about 180 feet of water pressure at the plug location which would require access methods that do not meet Reclamations safety standards. Therefore, all tunnel cleaning and plug construction must be constructed remotely through boreholes up to 30-inches in diameter.Plug construction will take place in the dry after installation of two cofferdams placed at opposite ends of the plug. Each of the cofferdams will be formed from a pair of geotextile bags inflated with grout and pinned into place tunnel with I-beams. The geotextile bags will be separated by 25-feet and the interior tunnel space will be filled with concrete. Water pressures will be equalized on upstream and downstream sides of the cofferdams during installation by pumping from newly constructed wells upstream of the plug into an existing well located downstream of the plug location. The iron hydroxide will be removed from the walls using a chain flail mounted on a drill string and rotated using a drill rig at the ground surface through a series of 30-inch diameter boreholes along the plug length. High pressure water cleaning will also take place prior to cofferdam construction. Trash pumps will be used to lift debris and cleaning water out of the tunnel.The 60-foot long concrete plug will be placed between cofferdams after dewatering, cleaning and camera inspections. Concrete will be placed from the ground surface to fill the plug area. Two epoxy coated steel I-beams will be installed in and grouted in place via 12-inch boreholes intersecting the plug for additional shear capacity. Contact grouting of any shrinkage gaps between the plug and tunnel ceiling will then take place followed by pressure grouting of the bedrock within 20 feet of the tunnel walls, ceiling and floor.Who should attendCompanies with the technical expertise to drill boreholes to within 0.5 degrees of accuracy through the glacial soils and bedrock to 380-foot depths and with diameters ranging from 2.5 inches to 30 inches, perform remote tunnel cleaning or camera viewing activities, placement of concrete from 350 feet above the tunnel ceiling and installation of temporary cofferdams. Companies with experience performing cleaning, cutting, demolition and debris removal either through boreholes or limited access pipelines and companies with installation of hydraulic mine bulkheads.PurposeThe intent of Industry Day is for industry and Reclamation to improve the understanding of Government requirements and industry capabilities.As well, Reclamation is seeking feedback from industry on how to best combine the technical aspects of the work to minimize risk to potential contractors and the government, project cycle time, and overall cost.Industry day will allow attendees the opportunity to speak directly with Reclamation contracting officials and project leads about their capabilities and recommendations with the planned procurement activity.Date and LocationIndustry Day will be held on August 27, 2019 from 8:00 AM to 4:30 PM at the Renaissance Denver Stapleton Hotel, located at 3801 Quebec Street, Denver, Colorado.Those that plan to attend will need to register by contacting Contracting Officer,Gerri Voto-Braun via email by COB on August 23, 2019. There is no registration fee to attend. No meals or beverages will be provided at the event by Reclamation. There will be time provided for companies to meet one-on-one with the Government personnel for no more than 20 minutes each. If you are interested in participating in one of these sessions, please request this from the Contracting Officer as well. These sessions will be scheduled on the order in which the request is submitted.Additional InformationIndustry Day does not constitute a formal solicitation for proposals or proposal abstracts. Attendance is voluntary and is not required to propose any potentially related agency announcements or potential solicitations on any discussed topics. Reclamation will not provide reimbursement for any costs incurred to participate in Industry Day.Contracting Office AddressBureau of Reclamation2021 4th. Ave N.Billings, MT 59102Primary Point of ContactGerri Voto-Braun406-247-7809gvotobraun@usbr.gov