Location: Seattle, WA

Owner: Group Health Cooperative

Structural Engineer: MLA Engineering

The existing basement room was renovated to provide adequate radiation shielding for new linear accelerator medical equipment.  A portion of the existing drop-panel slab was removed and replaced with a high-density concrete slab along with an area of steel plate and lead shielding.  A high density concrete wall replaces one of the original columns that supports the slab.  A portion of the slab-on-grade was removed and replaced to accommodate a recessed pit for the equipment as well as M&E conduit.  The design required creative structural modifications that integrated lead into the structural slab to allow traffic and pedestrians to safely occupy the exterior drive area over the equipment room. MLA also provided shoring design for the contractor, GLY Construction.

High-density, steel aggregate concrete and lead-lining were designed by MLA Engineering to provide an effective shield against gamma rays.  The existing concrete roof over the LINAC room was used as an emergency vehicle driveway and entry to the Group Health facility.  With only limited headroom and an existing grade above the LINAC room that could not be increased, MLA’s creative combination of materials provided the necessary safety without compromising the driveway or use of the LINAC in the room below.