Inactive Total Small Business Set-Aside (FAR 19.5)

The Leadville Mine Drainage Tunnel 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... The Leadville Mine Drainage Tunnel 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 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 several locations in unstable rock and soil downstream of the granite and mine workings preventing access to the upper portions of the tunnel. Reclamation is considering plugging the tunnel upstream of the collapses to limit clean groundwater migration into the tunnel flows sent to the treatment plant, increasing treatment efficiency and lowering treatment cost. Reclamation has selected a plug location approximately 5,100 feet upstream of the tunnel portal and 325 feet below grade. Depth to groundwater is typically 180 feet and the tunnel at the plug location is believed to be a standard horseshoe shape, 10.5 feet high and 9.0 feet wide. The tunnel was constructed with a 20" vent pipe, 8" pressurized air line and 2" water line. The material and wall thickness of the different lines is unknown but assumed to be steel or aluminum. A narrow gauge railroad track supported on timber beams was installed along the tunnel centerline for construction. The tunnel is likely coated in gunite and mine water precipitate or sludge. Attempts at viewing the condition of the tunnel with remote cameras have been largely unsuccessful due to the cloudy mine water but are available on request. A typical tunnel cross section is shown in Error! Reference source not found. below, taken from construction records of the tunnel. We assume the railroad track, 8" and 2" pipelines are intact and the walls are coated in one to three feet of iron hydroxide. The 20-inch vent pipe has most likely been corroded away. Construction would begin by grading the site create a level drilling pad and new control house pad. A laydown area would be located north of the existing 46+96 control house and an adjacent settling pond would be constructed for drilling fluids. The temporary 60-ft wide, 215-ft long drilling pad would be constructed at El. 10,326 ft along the tunnel alignment from approximate stations 49+75 to 51+90 with 2:1 side slopes. A ramp up to the new control house pad at about station 52+40 and El 10,336 would be constructed at the southern end of the temporary drill pad. The control house pad will be 115-ft long by 55-ft wide. An access road to the new control house would be located to the southwest of the tunnel alignment with maximum grades of 6.5%. The site restoration plan includes regrading the temporary drill pad into an extended slope to enable vehicle access both along the access road and along the former tunnel alignment and provide additional space at the new control house. Three new wells extending to the tunnel, control house and the pipeline must be operational prior to construction of the cofferdams to help drawdown water upstream of the plug in order to reduce hydraulic head, and reduce leakage around the installed cofferdams prior to grout bag inflation and pressure grouting. Therefore, construction of the control house, pipeline extension to the existing 46+96 facilities and SCADA system installation would take place next. Drilling of the 30-inch holes for the subsequent cofferdam and plug construction may take place while the control house and related facilities are under construction. Five 30-inch holes for the concrete plug, four 30-inch holes for the cofferdams and two 8-inch holes for the cofferdam annulus concrete placement would be drilled. Downhole camera inspections of the cofferdam holes would take place following drilling to assess the existing condition of the tunnel interior, identify existing infrastructure or tunnel support elements, and to provide a baseline for cleaning operations. Mechanical cleaning consisting of a rotating chain flail type device followed by high pressure water jet cleaning would be performed in the area where the grout bag cofferdams will be constructed. Water jet cleaning can exceed pressures of 20,000 psi to remove chemical sediment on the tunnel walls, disconnect existing pipelines, railroad ties and loosen and move ballast off the tunnel floor. Existing railroad steel rails and the compressed air steel pipeline may not be removed by either the rotating flail and high pressure water cleaning. Alternative cleaning methods may be employed such as remote cutting technology by a specialty contractor either with diamond saws or plasma cutting. All work would be performed remotely from the drilling pad ground surface and in the wet. Removing or displacing the railroad track and pipelines is desired for ensuring the grout bags are not punctured on inflation and are able to sufficiently seat against the tunnel walls. Additional camera inspections would be performed to determine whether more cleaning was needed and to judge the effectiveness of alternative cleaning techniques for use in the main plug area. Following verification of sufficient cleaning, geotextile grout bags would be deployed at four locations. Neat cement grout or concrete will be tremied into the grout bags from the surface to inflate the grout bags and seat them against the tunnel walls. After grout set, the 30-inch diameter holes would be redrilled with 12-inch bits to a depth 10-ft below the tunnel bottom. Epoxy coated W10x68 beams will be installed in each of the 4 holes, which penetrate each of the cofferdams, extending 10-ft above and below the tunnel crown and floor, respectively. These beams will provide additional shear resistance to preclude movement of the grout bags during construction. The contractor may opt to place the beams in wet concrete instead of redrilling the holes but would be required to provide a method to verify that the beams were placed to correct depth. Next, the 8-inch holes between cofferdams will be used to pour high slump type V concrete mixed with fly ash and fiber reinforcement into the space between each pair of grout bags. Cleaning of this space will not be possible from the grout bag holes, therefore the existing railroad tracks, pipes and debris will have to be left in place. The concrete will serve to reinforce the grout bags and will provide an additional frictional component to resist movement of the cofferdams due to differential water pressure. The final cofferdam configuration is shown in Figure 2. Once the concrete cofferdams have set, three 3-inch diameter grout holes will be drilled through the concrete portion of the cofferdams and be pressure grouted to seal any leaks between the cofferdam and tunnel walls. Leaks may be caused by shrinkage of the placed concrete or places where the grout bags were unable to seal against the cleaned tunnel walls. After construction of the cofferdams, dewatering would begin by using the new upstream wells to drawdown as much head as possible upstream of the cofferdams. The existing well at 46+96 would also be used to control water pressures downstream of the cofferdams. Pressures upstream and downstream of the plug area would be monitored through existing and newly placed piezometers and the 30-inch holes between cofferdams. A pair of trash pumps linked together would be lowered down the downstream most 30-inch hole capable of removing solids up to three inches in diameter and pumping 350-ft of head. The bottom most trash pump will be placed in the downstream most borehole over drilled 10-ft below the tunnel bottom to create a sump. The second trash pump would be suspended approximately mid-way down the borehole to aid in pumping to the ground surface. Cleaning operations and camera inspections would then take place in the dry between cofferdams. Some leakage of the cofferdams is expected. Debris produced by cleaning would be funneled toward the trash pumps by gravity flows. Camera inspections will be more reliable in the dry and additional alternative methods of cutting and displacing the steel rail and pipelines such as the controlled use of thermite, remote plasma or diamond cutting, or other means would be then possible. After verification of sufficient cleaning to ensure a suitable bond between the plug and tunnel walls, the main plug would be poured with type V concrete through each of the 30-inch diameter holes. The concrete mix would include fly ash and fiber reinforcement to limit shrinkage cracking. Pours would take place in each of the 30-inch holes to ensure complete filling of the space between cofferdams. After initial concrete set, 12-inch diameter holes would be drilled to 10-ft below the tunnel floor in each of the concrete filled 30-inch holes used to pour the concrete plug. Epoxy coated W10x68 beams would then be installed in the bottom 30-ft of the 12-inch diameter holes and grouted to the surface. The beams will provide additional shear resistance to the plug in case of poor bonding with the tunnel walls. Finally, thirty-four 3-inch diameter grout holes will be drilled as 18 primary, 5 secondary, and 11 tertiary holes to produce a tight seal between the concrete plug, tunnel walls, and any discontinuities in close proximity to the tunnel. The grouting would include water testing to evaluate grout effectiveness. The grouting would be targeted at the tunnel-plug seal and the 20-ft of bedrock above, to the sides of and below the tunnel walls. The final plug configuration and limits of the grouting program is shown in Figure 3. All drill holes would be backfilled to the surface with non-shrink grout. With this work completed, the site would be restored and revegetated. The Government is looking for potential small business, small disadvantaged, HubZone, woman-owned or service disabled veteran owned contractors with the specialized experience and resources necessary to successfully complete a project of this size, scope and complexity. The NAICS Code for this project will be 237990, with a small business size standard of $36.5 Million. The Government anticipates that we will be issuing a solicitation for the Hydraulic Plug project around January 2020 and will award in July 2020. The estimated range of the project is $15 to $25 Million. The time allowed for completion of work will be 950 calendar days due to the short weather window at this high-altitude site. If a small business believes they are qualified to perform this project, they shall submit a capability proposal demonstrating their ability to successfully accomplish the various components of work for the Leadville Mine Drainage Tunnel Hydraulic Plug project, as described above. Potential contractors shall demonstrate their ability to successfully accomplish the various components of work for the LMDT Hydraulic Plug procurement. Potential offerors shall furnish a list (no more than 5) of Federal, State, local government, or commercial projects completed within the last 10 years that are similar in scope and complexity to the work required under this solicitation. The offeror must clearly demonstrate the ability to successfully complete projects in a timely manner, manage a variety of construction disciplines, and work collaboratively with owners. Projects similar in scope and complexity are defined as work involving the following: 1. Design and installation of dewatering systems, control of water after excavation (i.e., unwatering). 2. Drilling deep (>300 feet) and large diameter (>24-inches) drill holes. 3. Construction of water conveyance pipelines and associated control systems. 4. Installation of Supervisory Control and Data Acquisition (SCADA) systems. 5. Demonstration of collaborative efforts with the owner to maintain the project schedule. The following information shall be provided for each project: • Name and location of project. • Description of work. • Note whether or not offeror was the prime contractor and what portion of the work was performed by the offeror and what portion was performed by subcontractors. • Original completion date and actual dates and duration for each project (including modifications). • Initial contract amount and final contract amount (including modifications). • Name, address, and phone number of CO/owner/COR/point of contact who may verify information for this project. • Any problems encountered in performance of the work and corrective actions taken. Failure to provide the detailed information required above will result in the contractor being determined to be incapable of successfully performing this project and will be eliminated from consideration. Capability statements must be submitted no later than September 3, 2019. They shall be sent to gvotobraun@usbr.gov.