- Company: GMC Contracting
- Industry: General Building
- Location: Denali National Park, Alaska
- Expected Completion Date: July 1, 2016
- Project Website
Denali Park and Preserve is often called the “Crown Jewel” of the National Park System. The Park was established in 1913, and a Headquarters Village with modern amenities was first established in the 1950’s: water, sewer, and electrical distribution systems, a road system, and over 100 buildings (residences, apartment buildings, and office and shop buildings) were constructed. The 70-year-old water and sewer systems had outlived their useful lives by 2014: GMC contracted with the National Park Service (NPS) to replace the existing steel pipes with over 14,000 feet of direct-bury insulated “Arctic Pipe” (an HDPE inner pipe, with 2 to 4 inches of insulation and an outer HDPE or corrugated metal pipe jacket. Heated glycol lines (water tempered by antifreeze) were built into the insulated pipe, and circulated hot water next to the conduit pipe to keep the liquids above freezing temperatures).
The pipes were buried 10 feet, and generally followed the existing street and road system: the entire roadway system was rebuilt and re-paved after the pipes were installed. The existing utilities were contained in 3-foot by 4-foot concrete utilidors, which were insulated with asbestos (the popular choice in the 1950’s). GMC abated the asbestos-containing materials as we encountered it.
Other improvements include insulating the community leach field, installing a propane storage and distribution system, installing new propane-fired hydronic heating boilers in many of the buildings, insulated manholes, fire hydrants, and valves, and plumbing, electrical, and structural repairs and improvements throughout the project.
Winter snow and temperatures reaching -40° keep the park closed, and the roads impassible, from October 1 through May 15 each year. Because this is one of the most heavily visited parks in the nation, the Park had to remain open to visitors, and fully staffed, while the work was occurring. All work had to occur with minimal impact to the park staff, and no impact to the visiting public. GMC performed the work during the 5 thawed months of 2014 and 2015.
Substantial Completion was reached in September 2015; the final details, landscaping, and Acceptance will occur by July 1, 2016.
What impact does this project have on America?
Denali Park and Preserve is visited by over 400,000 people every year during the 5-months that it is open. The Park and Preserve covers more than 6,000,000 acres (9,400 square miles): about the same area as the State of New Hampshire. A visit to Denali is considered by many to be the "trip of a lifetime" because of the rugged beauty and remoteness of the country, the unique ecosystem, gorgeous mountains, Northern Lights, and the opportunities to see moose, bear, wolves, eagles, wolverines, beaver, and other creatures in their natural habitat. In order to provide and maintain access, provide visitor information and services, and protect the environment from the wear and tear of the crowds, about 200 NPS employees and their families live in the Headquarters Village and work in the Park.
The aging and increasingly inefficient infrastructure made it difficult to provide safe housing and workplaces for Park Service employees. Without the pipe replacement and associated improvements that were made under this contract, it would have become increasingly difficult, and eventually impossible, to provide the staffing and services upon which the public depends for safety, comfort, information, and education. Performance of the work without disturbing the Park Service staff and the visiting public made it possible for the park to remain open while the work was occurring. Families who had planned their visits (sometimes for years), and who had spent thousands of dollars to come to Alaska, were able to explore and enjoy the Park's wild beauty without limitation.
What interesting obstacles or unusual circumstances did you overcome to complete the project?
Denali Park and Preserve is located high in the Alaska Mountains, 265 road miles from Anchorage and 120 miles from Fairbanks. The remoteness of the location complicated the logistics of provision of materials and equipment: the nearest hardware store or rental yard was a 5-hour drive away (one-way). Our workforce of up to 30 people had to be housed and fed outside the park, without using up the Park's limited space and lodging resources. Servicing equipment was complicated by having to stock every wear part, filter, fuel, and lubricant for a large fleet of earthmoving equipment, and to anticipate possible problems so that they could be solved before they occurred. The mountainous terrain also limited cellular communication: there were only certain places on the project where voice and data communication could be made with the rest of the world.The typical roadway width in the HQ Village was 20 feet, with vegetation and buildings on both sides that could not be disturbed. Since trench depths were generally over 10 feet, the trench construction completely removed the roadway in the work area, even with the use of trench boxes to minimize trench widths. Contract requirements to avoid disturbance of vegetation and buildings required that spoil from trench excavation be loaded directly into articulated "heavy hauler" trucks, which would transport the material to the tail end of the trench for reinstallation as backfill. Performance of the work while leaving the existing infrastructure in service in the same locations required careful excavation and innovative techniques. The "round-robin" delivery of material from the excavator to the tail end of the trench minimized the impassible section of trench, and allowed park residents to continue to have access to their residences, shops, and offices at all times. Equipment noise also had to be kept to a minimum to avoid disturbance of wildlife, shift-workers, the dog-mushing kennel, people at work, and park visitors.The existing pipes had been constructed inside concrete utilidors, which are tunnels 3 feet wide by 4 feet high. The utilidors ran all over the entire project in roughly the same alignment as the new pipe, but offset a few feet: they were a constant impediment to smooth progress in the new work, since our crews had to go over, under, or through them without disturbing the utilities inside.New hydronic heating systems, with new propane-fired boilers, were installed in many of the buildings: in order to accomplish this, GMC installed a new propane storage and distribution system. Our crews also made the plumbing and electrical modifications to complete the installations. The new water and sewer services entered each building through its foundation: GMC cut holes in the concrete foundation wall, installed the new services, and repaired the wall in kind; GMC also installed new chimney chases for the new propane boilers in many buildings. Since almost every building in the Park is on the National Historic Building Register, we made these repairs and improvements without disturbing the surrounding structure, and in stylistic harmony with the rest of the building. Besides the challenges of matching the existing log and rough-hewn construction styles, we did our work while families were living in the houses, without disturbing their daily routines or personal possessions.Since the existing system had to be kept in service until the new system was operational, the utilidors were a constant impediment to the otherwise-smooth progress of the work. Each new system had to be completely installed and tested at each building before a cutover could be made: all of these cutovers were done smoothly , and we received accolades from the Park staff for our efforts.The original utilidor system had been heated by steam generated in a central boiler building, which heated the utilidors. The new system consisted of insulated pipes containing glycol heat trace lines to keep liquids in the carrier pipes thawed. GMC renovated and remodeled the original boiler house to become the glycol heating and circulation pump house. Old asbestos-containing insulation and gaskets were removed along with the unnecessary equipment, and new equipment was installed to replace the old steam generators.The glycol-tempered hot water supply and return lines were connected as the pipe was installed throughout the project: every bend, tee, and fixture had to have three lines (carrier pipe, glycol supply, and glycol return) connected and pressure-tested before proceeding. This made every joint a complex enough proposition that every fitting became a unique "special" that would only work at its engineered location. We are pleased to say that this work went off almost without a hitch, and the system now works excellently as designed.
What dangers and risks did you encounter, and describe any extraordinary methods used to keep workers safe?
The biggest risks on the project were associated with deep trenches in granular material: we had to install the pipe in these deep trenches while maintaining trench surface widths less than 20 feet. We used 8-foot-tall trench boxes, sometimes pinned together 2-high, to ensure worker safety. We also used temporary pedestrian fences, barricades, and signs to keep keep non-construction personnel out of the work zone, and we held daily or near-daily meetings with the Park staff and residents. We would keep them informed at the meetings about where we were working, what we were doing, and where we were headed, and we would address the specific concerns of each resident and Park official as they voiced them.The logistics of working in a remote location presented risks to our construction schedule: every nut, bolt, gasket, and fitting had to be detailed and ordered months in advance, and spare parts for every piece of equipment had to be held readily available to minimize delays: every "down" day would cost over $15,000 in direct costs even if no work occurred. The time loss of delays was also significant: a day lost in June or July, when it was light 24 hours a day, dry, and temperatures were in the 70's (f) could not be replaced equally in the fall when daylight was shorter, the rain and snow were constant, and the temperatures were in the 20's and 30's (f). Careful planning, anticipation of problems and delays, and careful tracking of materials delivery ensured success for the project.
How did you leverage new technologies to work faster and reduce waste?
GMC used the HCSS "Heavybid" estimating system to build an extremely detailed, complex work plan, which we easily adapted to a Microsoft "Project" schedule, and which we exported into our Sage "Master Builder" accounting software. Since a construction estimate becomes in fact the budget for a project, we also used a successor version of the "Heavybid" estimate (a copy of the original estimate, but with a new name so that the original estimate remained archived "as bid") to maintain and forecast our budget as the work progressed: we estimated change orders, and we adjusted our estimates for work already performed to reflect actual vs. projected costs. We use the updated budget estimate to aid work-in-progress analysis, and to improve our historical foundations for future bids.The Denali Headquarters Utility Rehabilitation Project was unusual for 21st-Century construction in the United States for its communication limitations: its remote location, surrounded by mountains, made cell phone communication impossible throughout most of the project. Several times a day a member of the project management team would drive to particular locations within the park, and park facing a certain direction, to achieve cellular contact. There he would make phone calls and receive any text messages or voice mail that may have arrived. Another aspect of the communication problems we encountered is that the GPS controls that GMC has installed on our equipment could not function, because the mountainous terrain prevented line-of-sight satellite contact: our operators performed using the same techniques that were standard 50 years ago. We are fortunate to have a highly experienced workforce that has decades of pre-GPS experience: while our operators certainly have the knowledge and capability to use GPS controls, they also have the experience to perform excellently without it.In summary, careful project planning using scheduling software and worksheets allowed GMC to execute its work with most of the possible conflicts resolved well in advance of the physical work. The use of late-model, low-hour large hydraulic excavators, dozers, loaders, compactors, and articulated trucks allowed the work to be performed smoothly, so that deadlines were met, and the use of trench boxes allowed construction in the narrow work corridors to continue without endangerment of workers or encroachment on the surrounding areas.This project generated almost no waste: soils removed for pipe installation were placed back into the trenches, and the small amount of packing debris we generated was collected in trash bins for disposal at the Fairbanks North Star Borough Landfill. GMC took pains to collect any trash or debris daily, so that the pristine surroundings of Denali National Park and Preserve remained glorious and unsullied.