Associated with the first stage contract for the Durango Pumping Plant, the foundation excavation has been completed, the concrete intake structure adjacent to the river placed, and the fish outfall structure completed.
The second stage contract, consisting of construction of the fish screen structure, the building housing the pumping units, the intake and discharge piping, the pumps, and landscaping work was awarded to Weeminuche Construction Authority (WCA) in the fall of 2004. The following work has been accomplished since award of the second stage contract:
Concrete construction work for the pumping plant was completed during the summer of 2007. Installation of structural steel for the roofing system on the pump bay portion of the building and the service bay has been completed, and the roofing system mostly installed. Some final grading around the plant has been performed.
Construction of the air chamber, consisting of a fabricated-in-place, 39-foot diameter steel ball, began in the spring of 2007, and has been completed. The roof will be installed on the concrete vault housing.
Installation of the fish screens and fish screen cleaning system was complete by 2007 summer's end. The retaining wall adjacent to the switchyard was completed during the 2006-2007 winter. Western Area Power Administration's construction of the switchyard and transmission line will be complete in the spring of 2008.
Work on the Ridges Basin 72-inch diameter discharge pipeline was started early in the summer of 2006 and was completed in the late fall of 2006. Construction work for the discharge line consisted of: 1) excavating a trench for the pipe; 2) placing and welding the mortar-lined steel pipe in the trench; 3) backfilling the trench and partially covering the pipe with soil cement slurry backfill; 4) and, finally backfilling the remainder of the trench back to the original ground surface with trench excavation material.
Overhead cranes within the pumping plant were installed during the fall of 2007. Architectural finish work on the exterior of the pumping plant structure was began in the fall of 2007, and will be completed in the spring of 2008. Delivery of pumps, motors, and associated electrical began in early 2008.
Work to be accomplished during the next six months includes completion of the roof structures; installation of pump and motor other miscellaneous mechanical and electrical equipment; and completion of general gradation work on the site.
Northwest Pipeline Inc./Enterprise: The three interstate gas and gas products pipelines owned by these companies were relocated out of the reservoir basin during the summer of 2003. Transfer of right-of-way is pending.
Atmos Energy: No current activity. Atmos gas pipeline, which is located in the upper portions of the reservoir pool, must be relocated prior to filling of the reservoir. A tentative alignment for this gas pipeline adjacent to the relocated/reconstructed County Road 211 has been selected.
County Road 211: Final designs have been completed and are in review. Weeminuche Construction Authority is in the process of preparing a proposal for construction of this road relocation. Award of a contract for this work is planned for the summer of 2008.
Several contracts associated with construction of the dam have been completed by WCA. Excavation for the outlet works tunnel portals was completed in 2003, as was excavation of the right abutment and construction of various haul roads. Under a foundation excavation contract, nearly 2.3 million cubic yards of earth materials were excavated during 2004 revealing the rock foundation for the dam. Also, associated with the foundation excavation contract were construction of more haul roads and some of the drop structures needed for Basin Creek improvements. An outlet works tunnel excavation contract was awarded in 2004 and completed in 2005, as was a contact for supplying and erecting a materials processing plant needed for manufacturing filter and drain materials for the dam.
Dam Completion Contract: A contract for completion of the dam was awarded to WCA in 2005. Work associated with this contract includes: 1) completion of the Basin Creek Improvements; 2) manufacturing of the filter and drain materials needed for these dam embankment sections; 3) foundation grouting for the dam; 4) construction of the dam embankment; and, 5) completion of the outlet works including its intake structure, tunnel lining, control building and associated valves and piping.
Outlet Works Concrete Tunnel Lining: Harrison Western, subcontractor for the concrete tunnel lining construction, has completed placement of concrete for the tunnel’s invert and arch sections. They have also completed placement of the concrete lining in the gate chamber area located near the center of the 1,400-foot long tunnel. The guard gate and piping within the downstream tunnel has been installed. The jet flow, sleeve valve, and associated piping were installed during the fall of 2007 in the control house area.
Materials Processing Plant: The materials processing plant was purchased, set up, and operated for the production of the processed sand and gravel filter and drain zones within Ridges Basin Dam. Dam embankment construction is now complete, and therefore, the plant is being decommissioned and removed from the site.
Outlet Works Control House : Concrete work was begun on the outlet works control house and engine generator house located just outside of the downstream outlet works tunnel portal. Construction of these two concrete buildings continued through the summer, fall, and winter of 2007, and will be completed during the spring of 2008.
Dam Foundation Grouting: Blanket hole and curtain hole grouting has been completed from abutment to abutment for Ridges Basin Dam. Grouting to be conducted from the outlet works tunnel and gate chamber was completed during the fall of 2007.
Dam Embankment Construction: Upon completion of grouting work on the lowest portions of the dam foundation during mid-summer 2005, dam embankment placing operations were started. During this first embankment placing season, until freezing weather conditions in November of 2005 stopped the work, WCA was able to place about 30 vertical feet of embankment. Operations involved placement of the clay core; the sand filter and gravel drain zones of the embankment; the upstream and downstream shell zones composed of sand, gravel and cobble pit run material; and the miscellaneous materials zone used for refilling the excavation upstream of the dam embankment.
Dam embankment construction was restarted in April of 2006 and continued on a double shift, five days per week basis through mid-November 2006. By this time, the embankment had been constructed to about Elevation 6775. Embankment construction resumed in April 2007 and continued throughout the spring, summer, and fall of 2007. “Topping out” or completion of the dam embankment occurred in November 2007.Borrow Area B Development: The borrow area has been cleared and completely stripped of topsoil and clay overburden. The borrow area was used as a source area for the sand, gravel, and cobble dam embankment zone, and as a raw material source for manufacturing the sand, gravel drain, and downstream facing element embankment zones. This borrow area has also served to supply materials for construction of drop structures in Basin Creek; to supply materials for haul road sub-grades; and as a raw material source for manufacturing haul road gravel surfacing. With completion of the dam embankment, this borrow area will be graded to flatten steep slopes. Topsoil will be replaced and the area vegetated.
Borrow Area A Development: Borrow Area A has been stripped and pre-wetting performed for moisture conditioning. The Borrow Area A is used as a source area for the clay core portion of the dam. The clay material is selectively excavated from naturally occurring deposits of material with optimum moisture content or wetted to condition the material prior to excavation. As the borrow area is entirely within the reservoir area and eventually inundated, no attempt at restoration will be made.
Other Activities: Construction of Drop Structures 6, 7, and 8 were completed during the 2005-2006 winter. Construction of the remainder of the drop structures and most of the Basin Creek Improvement work began and was completed in the winter of 2006-2007. Work has begun on completing the Basin Creek Improvements upstream of Drop Structure 4, and will continue until completion in the spring of 2008. Completion of access roads, gravel surfacing, and dam embankment instrumentation will also take place during the spring of 2008.
Ridges Basin Inlet Conduit
Final specifications for the remaining portion of the inlet conduit were completed in February 2006. WCA prepared technical and cost proposals for Reclamation review with negotiations and award of a contract being completed in December 2006. Excavation work for installation of the pipeline began in January 2007. Manufacturing of the steel line pipe was initiated and the first shipments arrived at the site in April 2007. The contractor final excavated, placed, and backfilled bout 7,100 feet of the inlet conduit pipeline during the summer of 2007. Restoration of the disturbed right-of-way for this portion of the work was completed during the fall of 2007. Construction of concrete discharge structures began in the summer of 2007 and was completed in the late fall of 2007. Through the winter of 2007-2008, excavation and installation of the conduit across Bodo Creek was accomplished.
Trenching, installation of the remaining 1,700 feet of pipe, and restoration of the right-of-way associated with this work will take place during the spring, summer, and fall of 2008.
Navajo Nation Municipal Pipeline
Since the last update, the permanent right-of-way (ROW) and Temporary Construction Easement for the pipeline has been approved by the Navajo Nation and will now be forwarded to the Bureau of Indian Affairs for their review and approval. This process is expected to take from three to six months. Also, an agreement between the City of Farmington (COF) and Reclamation for the COF to perform the design and construction of the Farmington Reach portion of the NNMP has been executed. The Farmington Reach consists of approximately three miles of pipeline extending from the City’s1C water zone near the airport to a point on northeast bank of the San Juan River near Fire Station No. 6.
During the next six months, Reclamation will be working on the Designers Operating Criteria and Design Summary. The COF’s design for the Farmington Reach will be nearing completion. A horizontal directional drilling contract will be awarded for a section of the line at Nenahnezad Hill and the San Juan River crossings near Farmington and Hogback. We also anticipate beginning negotiations with the Navajo Engineering and Construction Authority on a master contract under P.L. 93-638 and beginning construction activities on the Fruitland Reach of the NNMP.
Monitoring is done to ensure adequate conditions are maintained within the MA. This includes conditions sufficient to maintain the existing and enhanced hydrologic conditions.
Monitoring results for 2007 are being incorporated into the annual report for Mitigation Area activities. Data indicates that there is no threat to the long-term viability for wetland/riparian mitigation credit. This broad mitigation category is considered successful.
Stabilization monitoring is complete for 2007. Data indicate that stability is being attained on all segments, to include the two segments where active stabilization construction has occurred. Data will be included in annual report for mitigation activities. This broad mitigation category is considered successful.
Reclamation has completed all degraded channel and floodplain restoration construction and revegetation. Further, Reclamation will continue to observe the affected area for functional stability. This mitigation category is considered successful.
Reclamation identified the need to eliminate undesirable livestock grazing and its negative affects. A contract was awarded to build field fence and construction was completed in January 2007. External boundaries of the riparian tracts have been fully fenced to exclude trespass grazing. This mitigation category is considered successful.
Integrated Vegetation Management work was completed in November 2007. Monitoring data analysis indicates that Reclamation has reached the goals for full mitigation success in this mitigation category (two years ahead of the expected schedule). Data is to be incorporated into Reclamation’s annual mitigation report.
The improvement of riparian buffers was included in the treatment activities for general integrated vegetation management described above. This included seeding, herbaceous weed control, and woody weed control. This mitigation category is considered successful.
In the FY 2007 effort, Reclamation surpassed the 95% completion of physical features milestone as set forth in the 2000 Final Supplemental Environmental Impact Statement (FSEIS) and the 2003 Wetland/Riparian Mitigation and Monitoring Plan (WMMP). The attainment of this milestone meets the FSEIS and Record of Decision commitment to reach this stage prior to the operation of the Durango Pumping Plant. Reclamation’s definition of the 95% stage was provided in the 2003 WMMP.
Also in the FY 2007 effort, full mitigation success was met, as defined in the 2003 WMMP. Current monitoring data analysis indicates that all mitigation goals were met or surpassed.
The Mitigation Area has been transferred to Operations and Maintenance status with some punch-list items to be addressed. On-going strategy development for long-term management continues.
Full Completion Statement : During FY 2007, full mitigation success for wildlife and vegetation in the Mitigation Area was met, as defined in the 2003 WMMP. All mitigation goals were met or surpassed.
Other Wildlife Mitigation: As dam construction is complete, monitoring of golden eagles in Ridges Basin is no longer necessary. There will be four years of during and post-filling monitoring to determine the effects of reservoir filling on territory occupancy.
The 2008 Scopes of Work for migratory bird studies in Ridges Basin, and Endangered Species Act requirements in the Mitigation Area, will be generated in March 2008.
Call Reclamation's toll free number for the latest construction information by phone: 866-720-0918