The Diamond Peak Culvert Repair
Within the Diamond Peak base area, Incline Creek is contained within a buried 72-inch diameter corrugated metal pipe (CMP) culvert running approximately 1,800-feet from just above the upper parking lot to just below the Schoolhouse Lift loading area. Additionally, there is a smaller 24 to 36-inch CMP branch culvert carrying tributary flows approximately 4,000-feet from mid-way up the Spillway run down the Lodgepole run, and past the Diamond Peak Skier Services Building where it intersects with the 72-inch CMP. These culverts were installed by Boise Cascade in the 1960s to facilitate the construction of the base area of Ski Incline (now called Diamond Peak). Along with Diamond Peak, the culverts are now owned by the District and the District is solely responsible for the maintenance and upkeep. The District has no as-built information or engineering drawings regarding the design, construction, alignment, or planned life expectancy of the culverts.
During the construction of the Diamond Peak Skier Services Building in 2010, the culvert was encountered in multiple locations. A brief field inspection of the interior of the culvert identified areas where spot corrosion had eaten through the entire culvert wall. Subsequent video inspections determined large sections of both the 72-inch CMP and the lower portions of the branch culvert had signs of structural deficiencies and must be rehabilitated. Starting in 2011, the District began planning and design of a multi-year capital improvement project to rehabilitate the 1,800-feet of 72-inch culvert along with the failing lower sections of the branch culvert.
This multi-year effort included condition assessment, hydrology assessment and watershed modeling, engineering analysis, engineering design, and construction cost estimating to develop a project approach to address these aging and failing District assets. In the summer of 2016, the District utilized newly available LiDAR (light detection and ranging) technology and high definition video to conduct a comprehensive assessment of the 72-inch and 36-inch CMPs and develop a 3D model of the pipe interiors to inform the final design approach and selected construction methodologies.
In June 2017, Diamond Peak experienced heavy run-off from the near record snowpack which caused areas of significant surface erosion throughout the lower mountain and damaged portions of the branch culvert beneath the Lodgepole run.
Leveraging the engineering and condition assessment data completed to date, the District was able to rapidly develop a design, procure the necessary permits, and complete replacement of approximately 2,065-feet of the branch culvert. Additionally, District Staff worked with the Federal Emergency Management Agency (FEMA) to qualify the repair work for 75% federal reimbursement. Approximately 1,500-feet of upper branch culvert, running along the Spillway run, was unaffected by the run-off and condition inspections indicate this portion remains in a reliable and serviceable condition. The District will continue to monitor this portion of the branch culvert to inform the planning of future capital budgets.
At the December 13, 2017 meeting of the IVGID Board of Trustees, District Staff presented a comprehensive report on the status of the Diamond Peak culverts that detailed the final condition assessment findings, the designed improvements, and recommended utilizing the Construction Manager at Risk (CMAR) contracting method to deliver the construction phase of the project. CMAR, as allowed under Nevada Revised Statute 338.169, is a hybrid contracting method that includes bidding, design, and construction with Owner, Designer, and Contractor working collaboratively to reach a constructible and cost effective approach. CMAR has been successfully utilized by numerous agencies throughout the
State of Nevada to reduce risk, schedule, and costs on projects with a high degree of complexity.
At the February 7, 2018 meeting, the IVGID Board of Trustees awarded a competitively bid CMAR contract to Q&D Construction to complete preconstruction services. Under this contract, Q&D Construction worked with District Staff, the Engineer of Record, CH2M, and the onsite construction oversight representative, Tri Sage Consulting, to develop, estimate, and provide design input for the replacement and rehabilitation of the entire length of 72-inch CMP and the remaining un-replaced lower portions of 36-inch CMP in the Diamond Peak base area (totaling approximately 400-linear feet). Q&D Construction was also responsible for the public, competitive bidding of any subcontracts associated with completing the work.
The CMAR preconstruction phase culminated in the open book development of a guaranteed maximum price contract with Q&D Construction to complete construction of the project in the summer and fall of 2018. This contract will be presented for award to the IVGID Board of Trustees at the May 23, 2018 meeting. If awarded, the project is anticipated to take approximately 80 working days to complete. The work will begin in early July and be completed by the October 15th Tahoe Regional Planning Agency grading deadline. The project will be completed utilizing a mix of open trench installation and innovative pipe slip-lining techniques.
After 7 years of extensive planning and design, the summer of 2018 will see a flurry of construction activity at Diamond Peak to ensure the culverts running through the base area are safe and functional for generations to come.
Inquiries about this project can be directed to the District’s Director of Asset Management, Bradley A. Johnson, P.E. who can be reached at email@example.com
• Technical Specifications
• Incline Creek Culvert Rehabilitaiton Project Plans
• Upstream Channel Restoration Plan & Profile
• Dewatering Plan
• Draft Contract Documents:
Culvert update 9/12/2018:
The upper 400’ of 60” Steel pipe slip-lining was completed this past Saturday. This is a huge milestone for the project as it was the piece of the project with the most complexity. The 60” steel pipe will now have grouting around the pipe to fill the annular space.
The focus now turns to the 72” open trenching. This is a much more straight forward approach of pipe installation with a high production rate. As of today there is 500’ of 72” HDPE has been installed of a total of approximately 1,400’. Currently we anticipate an October 15th substantial completion date.
Culver update 8/31/2018:
The Contractor has inserted 400 linear feet of the 60” diameter steel pipe. The boring machine that pushes the pipe is getting re-positioned to push the remaining 400 feet. The open trench excavation and 72” pipe replacement began this week. Production rates for installation of the 72” pipe will increase as the depth of excavation is reduced.
Culvert equipment staging is underway, July 25, 2018: