Detachable Boom Does Double Duty in the Land of the Midnight Sun
“The season is short but the hours are long.” That’s how R.J. Stevens describes pumping concrete in Alaska. And the company can work well into the night when summer daylight is a 24 hour proposition. His company, McKinley Concrete Pumping, Wasilla, Alaska is currently pumping the largest parking structure in the state using a separate placing boom – a first for the state’s construction industry. Because of the demand for Stevens’ service, the company is taking advantage of the detachable feature of the firm’s placing boom to perform as a truck-mounted boom when it is not mast-mounted on top of the parking garage.
The 10-story parking structure will serve the new Dena’ina Civic and Convention Center in downtown Anchorage. It will accommodate 836 cars when completed in the Fall of 2008. Two 53-foot masts were incorporated into the pumping plans to support the detachable boom from the Schwing KVM 39X Generation 2 truck-mounted concrete pump. The 39-meter boom reaches 114-feet horizontally allowing it to reach all areas from two locations on the structure with its 550-degree slewing range.
The 400’ x 80’ structure is divided into thirds for forming and pouring. Each 390 yard pour is accomplished in approximately 10 hours. “The finishers control our progress and the concrete is tough to finish because of the low water content,” Stanley explained. Because of the heavy use of salt in the urban areas of Alaska during cold weather, the mix design utilizes anti-corrosion additives.
The Generation 2 design provides a dedicated separate powerpack/reservoir for the placing boom when it is mounted on a mast. This also allows the flying boom to enjoy the lowest weight to reach ratio in the industry. Weight was particularly important to Stevens who relied on a mobile crane on ground level to move the 12,890 pound boom between masts and back to his truck pump when needed.
“It goes up and down like a yo-yo,” explains Stevens, “We pump twice a week on the garage and then the boom goes back on the truck to take care of our residential foundation customers.” The McKinley crew has the boom off the mast and back on the pump in 45-minutes. Four pins and nine quick-attach hydraulic hoses are all that are needed to reconnect the truck pump to the placing boom.
When the pump and boom are off the garage site doing conventional pours, the mobile crane raises the masts. Floor frames secure the mast in deck openings on two levels with a pin and wedges. Crews place a floor frame in an opening on a recently poured deck, raise the boom, repin it and install wedges to stabilize it in the frame. A third floor frame is staged for installation in the next deck as the structure rises.
Once the masts have been repositioned and the truck-mounted pump with placing boom has returned to the site, the boom is detached and lifted by the crane onto one of the masts. The truck mounted pump is then positioned to feed the placing booms through 250-feet of horizontal and 260-feet of vertical line. The pump is placed equidistance between the mast positions outside the structure. A diversion valve directs concrete flow to either the east or west mast location.
Stevens credits, in part, the 2023-5 130/180 MPS pumpkit that comes standard with detachable boom KVM 39s combined with the manufacturer’s successful Rock Valve. “The high pressure capabilities of this pump are paired with an M Rock that has an axial bearing on the shaft,“ explained Stevens, “The longer shaft and bearing on this Rock Valve distribute the loads generated by higher pressure pumping for long term reliability. We don’t see a lot of pump service guys up here,” he states, “And I haven’t needed one.”
McKinley also operates a 1999 Schwing KVM 34X with 21,000 hours on the hour meter and another KVM 39X. Stevens stresses the importance of safety and efficiency to his operators, “When you run this hard, pump reliability is of utmost importance. But the operator is the major component of a successful pumping business.” In this regard, McKinley operators are ACPA certified.
Past projects for McKinley concrete pumping include 10,000 yards for deep foundations at the Anchorage International Airport and a 7,770-yard slab-on-grade pour for a new Target store.
Alaska has about 640,000 residents spread out over 570,374 square miles. This land mass is equivalent to 20 percent of the lower 48 states which makes it the largest state. With plenty of room to grow, the prospecting is good for McKinley Concrete Pumping. “Living in Alaska is not for everyone,” he said, “Having been born and raised here, it is a thrill to be creating some landmark structures using new methods.”
Project: Dena’ina Civic and Convention Center Parking Structure
Owner: City of Anchorage, Alaska
Architects: RIM Architects, Anchorage, AL and LMN Architects, Seattle, WA
General Contractor: Neeser Construction Inc, Anchorage, AL
Concrete Pumping Contractor: McKinley Concrete Pumping, Wasilla, Alaska
Equipment: Schwing KVM 39X with Generation 2 Detachable Boom, Schwing KVM 34X