Redevelopment of the Climate Pledge Arena.

Just north of downtown Seattle, Malcolm Drilling was contracted to help construct a 74-acre state of the art sports complex known as Climate Pledge Arena. The plans for the redevelopment of the new complex included preserving the iconic roof. Malcolm’s crews quickly got to work installing 82 temporary shafts to support the existing 44-million-pound roof. In addition, 178,000sf of permanent shoring consisting of soldier piles, lagging and tiebacks were utilized to create an excavation that proceeded 70-feet below existing grade.

To build up the new foundation that would take over the 57-year-old roof, Malcolm installed 117 permanent shafts. The new excavation was positioned slightly outside of the existing roof line and encompassed a large new parking garage on the south wall.

Access to the work area was provided by a temporary access ramp. The ramp was constructed using an internal braced shoring system, that was completed in phases as the excavation progressed.


An eductor well system was installed to dewater a tunnel and portal alignment for construction of an underground trucking entrance underneath the new Climate Pledge Arena in Seattle, WA. An eductor well system uses a supply header pipe and a return header pipe to lift groundwater from individual eductor wells using a Venturi suction in each eductor well. The return header pipe comes out of each eductor well with more water than entered into the eductor well via the supply header pipe, thus removing groundwater on a net basis. Eductor systems are suited to dewatering heterogeneous or layered hydrogeologic strata that require closely spaced wells, but are too deep for vacuum wellpoints.

Eductor well layout plan surrounding tunneling portal alignment:
Schematic of eductor well construction, with supply and return header pipes: