The City of Fernie’s Fairy Creek reservoir is the community’s primary potable water source, on a remote forested site in southeastern British Columbia. A new ultraviolet disinfection system had to be installed inside the existing valve chamber - a live, moisture-exposed concrete structure with incomplete record documentation. I took over structural responsibility mid-project in December 2025 and carried the discipline from concept through the 95% design milestone and toward issued-for-construction.

My Role

Structural Engineer of Record. Sole structural ownership following a mid-project handoff, through to the 95% milestone and tender.

What I Designed

Design basis

  • Authored the structural basis-of-design criteria: governing codes, load cases, load combinations, deflection limits, and material specifications
  • NBCC 2020, BCBC 2024, CSA S16-19, CSA A23.3-19, CSA G40.21, CSA G30.18, ASTM A500, ASTM F1554

Post-disaster seismic design

  • Importance factor IE = 1.5 for a post-disaster water treatment facility
  • Conservative Site Class E assumption in the absence of any geotechnical report
  • Equipment seismic demands of 20.9 kN per direction on 38 kN of flexibly connected UV equipment, derived per NBCC 4.1.8.18

Steel equipment platform

  • Extension of the existing elevated actuator walkway to carry the UV equipment while preserving access to the existing valve actuators
  • HSS columns, steel framing, and galvanized grating analyzed by finite element model
  • Sizing governed by stiffness rather than strength for equipment sensitivity - L/480 beam deflection, H/600 column drift, peak stress utilization 0.71

Foundations

  • Seven new isolated reinforced-concrete pad footings kept fully independent of the existing building of unknown detailing
  • Construction sequence tailored to the moist chamber environment: sawcut the existing 150 mm slab-on-grade, excavate, CLSM backfill, new footing with waterproofing
  • 30 MPa interior and 35 MPa exterior exposure-class concrete

Pipe supports

  • Cantilevered HSS102x102x6.4 supports for 12-inch stainless UV reactor piping
  • Verified for the laterally unsupported flexural case to CSA S16-19 Clause 13 - 7.05 kNm factored against 25.6 kNm capacity

Designing Around Unknowns

There was no geotechnical report, the record drawings were poor, and existing member sizes were unverified. I made the design defensible anyway:

  • Adopted conservative 5-10% dimensional tolerances and up to 10% equipment-weight margin
  • Wrote explicit contractor field-verification requirements into the documents, transferring residual risk to construction where it could actually be resolved

Cost Review

I authored a Class A (AACE Class 1) unit-rate review, building up supply-and-install rates for galvanized steel, grating, demolition, and footings against remote-British-Columbia construction premiums. Grating was underpriced by 3-4x - the single highest estimate risk - and structural steel was overpriced by 2x. Flagging both protected the estimate against a material understatement before finalization.

Outcome

Produced the 95% structural drawing set and book specifications, QA reviewed in February 2026, and advanced the structural scope past 95% toward issued-for-construction and tender - all within a lean fee carrying no contingency for scope growth after the mid-project handoff. Coordinated structural scope across electrical, process, and building-mechanical disciplines throughout, managing scope creep by flagging out-of-scope requests as extras.