Columbia Boulevard Wastewater Treatment Plant Digester Mixing Project

Project Data
Year Completed 2014

Brown & Caldwell, City of Portland

Services Roofing, Waterproofing
Category Government, Municipal
Reference Catherine Dummer
Brown & Caldwell
6500 SW Macadam Avenue
Suite 200
Portland, OR 97239

Services Provided

Project Details

Project Details

Project Details

PRC was retained by Brown & Caldwell and the City of Portland to provide expertise for system selection and design for a variety of roofing and waterproofing scenarios for a complex, multi-year facility upgrade.  Rennovations and upgrades to the mechanical systems at the Control Building and Digesters of the Columbia Boulevard Water Treatment Plant, located in Portland Oregon, included the complete removal and replacement of the building’s 31-year old built-up roof systems.  The existing roof systems were installed in 1981 and are being replaced with a 2-ply SBS Roof System over the Digesters and a PMMA Extensive Vegetative Roof System over the Control Building.  The five distinct areas cover 41,200 SF.  The project includes:

  • Removal of the existing roof systems, lightweight insulating concrete and related sheet metal flashings.
  • Polymer modified topping mortar over the exiting concrete slab to provide positive slope to roof drains. (Control Building)
  • Polyisocyanurate rigid insulation and cover board over the concrete floating lids at the four digesters.
  • Reinforced liquid applied Polymethyl Methacrylate (PMMA) roofing and flashing system (Control Building)  
  • Extensive Vegetative Roof System including elevated concrete pavers, river rock, drainage boards, filter fabric and extruded polystyrene insulation (Control Building)
  • 2-ply Styrene Butadiene Styrene (SBS) Roof System applied with cold adhesive over primed gypsum substrate board (Digesters)
  • 18, 20 and 24 gauge stainless steel flashings with soldered seams at parapet walls, roof edges, counter-flashings, door thresholds and penetrations.
  • Full-time and part-time on-site Quality Control inspections provided by Professional Roof Consultants, Inc. during the 2-year construction schedule.