Conroy Creek, a mountain stream home to a resident population of Rainbow Trout, crossedHighway No. 99 in this section of highway via an existing SPCSP (Structural plate) Pipe Arch, measuringapproximately 2.4m wide × 2.1m high. As part of the design process for a highway upgrade project,Armtec provided pre-design technical support by offering a DCSP (Deep Corrugated Structural Plate)cross-section shape suitable for the span, rise, cover and hydraulic end requirements for the newcrossing. To provide improved fish passage, the creek crossing was designed to be on a flat gradientwith an outlet settling pool. The open bottom arch design was tendered with a span of 10.247m and rise of4.843m with an overall length of 30.08m.After detailed analysis by the Contractor and Armtec following project award, the structure was lengthenedto 33.68m and the upstream end wall was eliminated in favour of a rip-rap / non-woven geotextile slopeand cast-in-place end collar. The downstream end was redesigned with a cast-in-place end collar inconjunction with Segmental Concrete Block wingwalls, reinforced with Polyester Geogrid.Armtec retained the services of McElhanney Consulting Services to offer detailed design and fieldcertification services for the cast-in-place concrete footings, downstream end wall and upstream slopetreatments. McElhanney also conducted an overall geometry check of how the roadway fill slopes tiedinto the end walls and provided design details on the concrete / rock infill inside the structure directlyabove the footings.Following installation of the 2 m wide × 0.5 m high footings, the DCSP Structure was assembled, tightenedand backfilled in under 10 working days, making it possible to finish the project by the fish windowdeadline. After a few weeks of the structure being constructed, the drainage area was subjected to a floodevent of historical proportions and the Conroy Creek Structure ran atear its hydraulic capacity. With theconcrete collars and end treatment design in place, the structure was able to accommodate the flood flows– proving a successful design and construction was provided.
展开▼
