Runway Extension at Rural Maine Airport Enables Medical Flights
Extension Creates Easier Medical Evacuations: $11.5M Federal Grant Finances Sargent Corporation Project at Stephen A. Bean Airport in Rangeley
Crucial aerial medical evacuations can now take place from a rural section of western Maine due to the recent extension of the runway at Stephen A. Bean Airport in Rangeley.
Sargent Corporation of Stillwater, Maine, reconstructed the existing runway and built extensions at each end, providing an adequate runway to support air medical transport by LifeFlight, a non-profit, life-saving organization. An $11.5 million grant from the Federal Aviation Administration’s Airport Improvement Program (AIP) funded the project.
Bean Municipal Airport is a town owned, public use airport originally constructed in 1934. The airfield serves Franklin County in a mountainous, sparsely populated sector of the state, and is maintained by the Town’s Department of Public Works, with employee Rebekah Carmichael the Designated Airport Manager. Located two nautical miles from the central business district of Rangeley, the airport covers an area of 125 acres at an elevation of 1,825 feet above mean sea level, and has a single runway designated 14/32 with a 75-foot-wide asphalt paved surface. Prior to Sargent’s reconstruction effort, the runway was 3,201 feet long – too short to allow LifeFlight’s new fixed-wing aircraft to land safely.
LifeFlight's Beechcraft King Air B200, which supplements the organization’s three Agusta (Italian) air ambulance helicopters, provides greater speed and efficiency over longer distances. Equipped with all-weather capability, the powerful B200 twin turboprop can climb through freezing rain and fog. But it requires a runway length of 4,300 feet – 1,100 feet longer than Bean Airport’s former runway.
A Growing Need
In recent years the need for air ambulance service for the western part of the state has become more evident as the area gains popularity with tourists and recreationalists.
According to an Environmental Assessment of the airfield in 2017 by consultants Dubois & King, the year-round population of Rangeley is approximately 1,300 people, with a significant summer population increase to approximately 6,000 people. The consultant points out the region is known for its natural resources, mountainous terrain and scenic highways, which offer many year-round recreational opportunities. These include hiking on the Appalachian National Scenic Trail, skiing at two of Maine’s largest and most popular ski resorts – Saddleback Mountain and Sugarloaf Mountain – cross-country skiing, snowshoeing, and snowmobiling on 170 miles of trails.
But as the number of people visiting the area increases, so does the potential for rising numbers of accidents and occurrences of severe illnesses. And without access to an air-medical evacuation system, critically ill and injured patients might have to travel almost an hour on winding mountain roads to reach the nearest hospital. LifeFlight’s aircraft cover the entire state, including offshore islands, remote mountains and wilderness areas. The organization’s three helicopters and airplane are staffed by teams of critical-care transport nurses and paramedics.
Feds Chip In
While the need to extend Bean Airport’s runway was becoming obvious to Rangeley officials and citizens, they were also aware that their small community could not afford the price tag. Early estimates placed the cost at more than $10 million.
The town sought financial help from the government, applying for a grant from the Federal Aviation Administration. The request was backed by Maine’s congressional delegation. U.S. Senator Susan Collins, the Chairman of the Transportation Appropriations Subcommittee, wrote a letter co-signed by Senator Angus King and Representative Bruce Poliquin in support of the request. Consequently, in September 2018, Sen. Collins was able to announce that the Town of Rangeley would receive $11.5 million through the federal AIP to extend the runway at Bean Airport and make several other key enhancements to support air medical transport.
The $11.5 million grant for Bean Airport is part of a $205 million package of AIP supplemental funding. U.S. Department of Transportation Secretary Elaine Chao delivered the rollout of the AIP grants in Washington, D.C., in September 2018 that was attended by numerous grant recipient groups including officials from Rangeley.
“These grants will help revitalize and strengthen critical infrastructure projects at smaller and rural airports in a number of ways,” said Secretary Chao. “The upgraded aviation facilities will help smaller communities attract new businesses, support air travel, and provide new job opportunities. And most importantly, these improvements will not only expand airport capacity, but improve safety as well.”
The supplemental funding is in addition to the $3.31 billion already awarded nationwide in AIP formula funding, and finances grants to 37 airports in 34 states. The improvements include runways, taxiways, aprons, terminals, and other infrastructure projects.
Complex Geometry, Massive Quantities
The Sargent crew, headed by Travis Fernald, Project Manager, and Adam Tenan, Project Superintendent, broke ground in fall 2018 on the two-year project. Work involved not only reconstructing the original 3,201-foot 14/32 runway, but also constructing a 690-foot extension on the Runway 14 end and a 409-foot extension on the Runway 32 end. The Runway 32 end extension involved some cut and fill, but Runway 14 involved constructing an enormous all-fill embankment about 70 feet tall and 75 feet wide at the paved top surface. Fortunately, the original 3,201-foot 14/32 runway actually had a raised mid-section portion, a sort of elongated hump, which yielded useful surplus fill when it was excavated and re-graded.
Designed by Dubois & King of Caribou, Maine, with Guy Rouelle serving as Project Manager, the runway has an isosceles trapezoid-shaped earthen embankment that required approximately 550,000 cubic yards of fill. “It was a huge hill, and it was steep,” said Tenan. “The embankments were built with a 1.5 to 1 slope. The engineers designed it that way to minimize intrusion of the structure into wetland.”
Fill material included an estimated 380,000 cubic yards of rock that was drilled and blasted at the nearby Chick Hill borrow pit. This resource had been used successfully in prior airport-related projects and was near enough to the runway site that haul trucks did not need to travel local public roads. What’s more, the pit had enough suitable rock to produce the quantities of crushed stone needed to lengthen the runway – especially for the 14 end extension.
Drilling, Blasting, and Sifting
Maine Drilling & Blasting was responsible for shattering the rock, which generally consisted of a deep stratum of solid granite bedrock overlaid with about 8 to 15 feet of a finely stratified, shale-like stone. The blaster used Epiroc T40 drills to bore holes for the explosives. Much of the rock requiring crushing was processed by an assembly of portable Astec JCI-KCI jaw (primary) and cone (secondary) crushers, mobile screening and conveying units.
Sargent decided to accelerate pit production by using a team of excavators equipped with “sifting buckets.”
“Colby Currier, our Operations Manager, came up with the idea of substituting sifting buckets for the regular rock buckets on three of our Caterpillar 336 Excavators. Our own steel fabrication shop run by Red Rancourt built the special buckets.”
The sifting buckets function like inclined vibrating grizzlies – those thick bar screen assemblies mounted over the intake bin of screening/crushing plants. These scalp, or skim off, incoming rock that is too big for the screening plant or the task at hand. In contrast, when using sifting buckets, the Caterpillar operators crowd the raw material (blasted rock) as usual but then raise the bucket and shake it briefly before depositing what’s left in the bucket into a stockpile for hauling to the runway site. The unwanted smaller material spills out through the bucket onto the ground.
Building the massive earthen embankment called for the orchestration of a large fleet of heavy equipment at Chick Hill engaged in creating and processing different soil and stone material of varying sizes and compositions; transporting the products in capacious Caterpillar 745 Off-Highway Trucks to designated project locations; and depositing these diverse materials in assigned areas using varying placement strategies.
For example, the 5-foot-thick base layer of the embankment consists of screened or sifted blasted rock measuring 1-inch to 24 inches, which had to be placed in maximum lifts of 2 feet and compacted by a Caterpillar D8 or similar 40,000-pound machine. This was topped with a 3-inch-thick choking layer of screened and graded one-inch crushed stone. Next came the bulk of the embankment material – the inner core – consisting of common borrow or rock borrow, depending on location. Common borrow was soil containing up to 8-inch stone and no more than 40 percent fines (passing #200 sieve). This was placed in 12-inch lifts and underwent heavy compaction in order to meet the engineer-specified 95 percent modified Proctor density.
Two adjacent layers of rock with slopes of either 1.5 to 1 or 1 to 2 (rise over run) envelop the inclined sides of the embankment. The inner layer, paradoxically referred to as the outer core, consists of rock borrow similar to that of the base layer. But the inner layer grows thicker as it climbs from the base towards the crest of the embankment. Lastly, a 3-foot-thick stone fill “shell” forms a tough protective jacket over the sides of the embankment. This is a sifted or screened blasted product containing hard, sound durable rock that resists disintegration from exposure to water or weather. These stones had to be angular and rough to promote interlocking, weigh at least 10 pounds each, and have an average dimension of at least 5 inches. The largest stones could weigh up to 500 pounds and measure up to 36 inches.
Work Strategy for a Live Airfield
Tenan indicated they broke the project into two parts: During the 2018-2019 winter, they were able to work on the bulk fills for the extensions while the main runway was still active. They blasted rock at Chick Hill, processed, hauled and placed rock for the embankment base layer and stone shell construction, and also hauled unprocessed blasted rock for the inner core. The base layer and stone shell consisted of screened or sifted rock, but the inner core for RW 14 was almost entirely blasted rock borrow from the Chick Hill borrow pit. All slopes at RW 14 were a steep 1.5 to 1, while the very end of Runway 32, being perpendicular to the runway, was also built with a 1.5 to 1 slope. He noted that approximately 25 percent of the overall fill was rock borrow from Chick Hill, and the remaining 75 percent was common borrow from the excavation of the existing runway reconstruction.
Tenan pointed out that Part 2 of their work strategy took place during the summer of 2019. This was the reconstruction of the original main runway, so it had to be shut down to aircraft activity.
“This was our greatest challenge,” he said. “We had only 84 days to finish the embankment.”
During this limited time frame, Sargent completed the following work: excavated and reconstructed the 3,201-foot main runway section; crushed rock at Chick Hill for gravels and stones needed for the runway pavement structure; installed 11,000 lineal feet of underdrain; managed the installation of runway lighting and approach appurtenances by lighting subcontractor Moulison; and provided oversight for the placement of 11,000 tons of hot mix asphalt pavement by subcontractor Pike Industries.
Sargent finished Part 2 in just 75 days. The $11.5 million reconstructed runway was officially re-opened for traffic September 21, 2019, with some minor finishing work scheduled for spring 2020.