It was a typical winter day in south central Alaska. Temperatures reached a blustery low of minus 40 degrees F. Wind gusts topped out at 60 mph. And the natives hadn't seen daylight for more than 20 hours.
Architect Rod Booze and his fellow Building Team members (most are from Tennessee and Texas, mind you) were huddled in the substantially completed steel-and-concrete core of the new Mat-Su Regional Medical Center—with only a 10 mm piece of plastic sheeting shielding them from the brutally harsh environment.
The dilemma that day was how to keep the three-story structure “dried in” during the next winter blast. Bone-chilling temperatures and gusting wind conditions make routine construction in rural Alaska the ultimate challenge.
“One-hundred-twenty-mile-per-hour wind gusts were not uncommon,” says Booze, AIA, NCARB, ACHA, principal with Ascension Group Architects, Arlington, Texas, design architect on the $71.8 million, 215,000-sf replacement hospital and medical office building in Palmer, about 50 miles north of Anchorage. “Enclosing the building with temporary heat and lighting was the most critical path on the project.”
Nearly all aspects of the project, from the staged materials to the building itself, had to be protected from the elements during construction. Materials were stored in temporary buildings on site or within heated railroad cars, and the building was literally wrapped in a plastic envelope that was supported by a temporary timber frame structure.
“Even the deep foundations had to be thermally protected,” says Booze. Before the building's drilled piers could be poured, the team had to enclose each excavated opening with a heated tent for up to 24 hours, and for 72 hours after pours. Without the protection of a climate-controlled environment, the concrete would not cure properly.
“This is what the art of engineering is all about,” said Building Team Awards judge Daniel Murphy, PE, LEED AP, with Environmental Systems Design, Chicago, referring to the cold-climate construction techniques employed on the project.
Murphy and the other members of Building Design+Construction's 2007 Building Team Awards judging panel praised the Building Team for Mat-Su Regional Medical Center for overcoming the extreme conditions and myriad other construction and engineering challenges—including the need for seismic mitigation and the lack of established utility infrastructure near the remote site—to build the state-of-the-art medical facility.
“For the team—most of whom are from Tennessee and Texas—to work through all these issues to build this hospital in the middle of nowhere in just 14 months is commendable,” said judge Tracy Nicholas, VP with Alter Consulting Group, Skokie, Ill., and a BD+C 2006 40 Under 40 winner (BD+C March 2006, p. 49).
Completed in December 2005, the medical center is located smack dab in the middle of two growing cities—Palmer (pop: 6,920) and Wasilla (8,470). The new facility, which features 74 private patient rooms (with room for 50 more) atop a full-service hospital complete with a 22-station emergency department, six operating rooms, and a 14-bed intensive-care unit, replaces an outdated, 1950s hospital nearby. The breathtaking site is flanked by mountains on three sides and is within a few miles of two distinct seismic fault zones in the Matanuska Susitna valley.
“Seismic events, albeit not always detectable, are recorded on a daily basis,” says Booze.
To combat the seismic forces, structural engineer Structure Design Group, Nashville, Tenn., designed an ultra-ridged structure supported on a series of massive, 40x40-foot spread footings. Two-foot-thick vertical concrete shear walls extend the full height of the building and are anchored to the mat foundations to create a “monolithic structure that is capable of transferring and dispersing significant forces to the ground,” says Booze.
The building's foundation piers were drilled to extend below the seasonal thaw line. This approach was necessary in order to mitigate the effects of “frostjacking,” a seasonal upward force caused by the freeze/thaw cycle of the soil. During the summer months, when temperatures can reach 80 degrees F with 20+ hours of daylight, the soil thaws and becomes porous, retaining moisture. When temperatures dip in the fall and winter, the moisture-laden soil freezes, placing enough upward pressure to push building substructures right out of the ground.
A greater concern was protecting the building from sinking into ground. In arctic regions, permanently frozen soil, known as “permafrost,” can become unstable when thawed by the heat radiated from climate-controlled buildings and other structures.
“Permanently frozen soil has terrific bearing capacity for structural loading of buildings, but the frozen soil must remain frozen,” says Booze. “The 'heat bulb' effect created by the building can compromise the permafrost, resulting in settlement of the structure.”
To keep the permafrost frozen, the design team insulated the building's foundation from the soil. A layer of polyisocyanurate insulation, a vapor barrier, and five feet of compacted granular fill separate the concrete foundation mats from the frozen soil below.
Given the region's extreme weather, maintaining pedestrian access to the medical center was a top priority for the project team. Exterior screening walls, landscaped buffers, and a deep entrance vestibule shield visitors as they enter the building, while snow-melt systems embedded in key access paving, ramps, and handicapped parking areas ensure they have a clear path to the front door.
As patients enter the medical center, they're greeted with a warm welcome. Comfy lounge seating surrounds a large stone fireplace in the main lobby, which is adorned with soft, earthy-colored materials and finishes. The warm colors and stonework are carried throughout the building's main circulation corridor and into the separate departments.
With daylight being so scarce in Alaska during the winter months (less than four hours of daylight per day), the design team took extra measures to maximize natural light throughout the facility. Oversized windows measuring 6x7 feet were installed in all 74 private patient rooms and 10-foot-high glazing was specified along the main circulation corridor. The dining area and waiting rooms also feature large windows, providing picturesque views of the surrounding mountains.
Understanding that daylight can't do it all in Alaska, the team upgraded the interior lighting scheme in all main patient traffic areas (corridors, treatment areas, elevators, etc.) to exceed standards set by the Illuminating Engineering Society of North America.
Speaking to the success of the project, Mat-Su CEO Norman Stephens said the physicians and medical staff are still “very excited” about the facility, even after a year of operation. The medical center has also helped recruiting efforts, a huge challenge in rural Alaska. In the first six month of operation, medical staff increased by more than 10%, including much-needed surgeons.