24th Latornell Conservation Symposium November 23, 2017

“Thinking Inside the Box”

Christopher Pfohl, C.E.T., EP, Can-CISEC Sr. Aquatic Ecologist

Degraded “Cast in place” Culvert

Background / Design • Issues related to crossing design preference by

RAs regarding replacement of three sided structures (cast in place footings) for Box Culverts

• Conformance with Hydraulic models (culvert

sizing) • Preference to replicate form and function of the

open footing (channel meandering, substrate, groundwater input)

Form and Function

• Replicate channel planform • Maintain Thermal Regime (Cold/Cool water,

groundwater discharge) • Maintain suitable substrate (diversity of particle

size, no erosion) • Provide suitable conditions for aquatic life

Groundwater Discharge to Surface Water

Hyporheic Zone

Burnside Innovation • Create a perforated precast box culvert that

allows for groundwater input

• Maintain structural integrity, for design standards

• Incorporate Natural Channel Design concepts within culvert, inlet and outlet

• Improve/maintain aquatic conditions

Barefoot Box Culvert™ vs Clearspan

Barefoot Box Culvert™ vs Clearspan

Crossing Design Comparison

Culvert Type Barefoot Box Culvert™

Standard Box Culvert

Clearspan with Footings

Design/Engineering Same as Box Culvert Less More Construction Timelines

Same as Box Culvert Less More

Aquatic Conditions (GW Input, Thermal Stability, Morphology)

More preferred than Box Culvert

Less Preferred Preferred

Permitting (Agency Concerns, Time = $$)

More preferred than Box Culvert

More Time Less Time

Cost Same as Box Culvert Less More

Does this really work? • High quality watercourse, Pine River (Brook trout present)

• Existing conditions (cold water stream) with numerous GW inputs • Monitoring ground and surface water conditions (Piezos and AWLR) • Complications with monitoring (plugging the perforations)

• DFO Monitoring as built conditions for performance (channel

conditions, erosion, substrate) • Positive results obtained (upwelling and temperature)

Water Levels/Hydraulic Head

Water Levels/Hydraulic Head

Water Levels/Hydraulic Head

Temperature Monitoring Locations

Temperature Data

Temperature Data

Conclusions/Takeaways • No negative changes to existing conditions based water

temp data • Positive GW upwelling in perforations/piezos to support

critical habitat/potential temperature improvements • Improved conditions within culvert based on culvert

upgrade • Need additional candidate sites/academic study for

future monitoring (thermally stressed conditions)

Reasons why to use • Significant cost savings over clearspan/footing

option • Potential to reduce permitting time (time = $$)

over standard box culvert • Potential improvement to Aquatic conditions

(thermal and critical habitat) • No negative effects based on form and function

Video - Brook trout Spawning