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Spillways are structures built into dams to provide a controlled release of flows from the dam into the downstream area. Our spillways are designed to accommodate major water surge events and can withstand very high velocities.

Cement and concrete can be used in many different ways in spillway engineering. We use conventional concrete to build specifically shaped and sized tunnels or ramps down dam faces and other directions depending on requirements.

Subcon has strong expertise in the application of poured-in-situ and precast concrete products for new spillways as well as spillway repairs.


We typically recommend our precast coast matt for spillway revetments.

It incorporates a geotextile filterlayer bonded to the base of the mattress. This releases pore pressure but retains the bed material preventing erosion beneath the mattress.

Block matts are approximately 50% more stable than rock revetments. Our stainless steel anchor pin options can be used to provide further stability.

Block heights can be adjusted row by row to increase roughness and help mitigate against hydraulic jump.

We believe fish passages are one of the most important aspects of a spillway.

Our habitat solutions and engineered fish passage solutions have been used to provide fish passage across the full range of flow conditions.

We can incorporate resting pools and channels with shelter against predation and high currents for any height weir or dam.

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