One of the main purposes of the Headwall structure is to dissipate the flow ensuring that it doesn't disturb the watercourse its entering thus causing erosion.  In some cases the velocity of the flow will be excessive and will need to be slowed before it enters the watercourse.  One way of doing this is to place Diffuser/Baffle Blocks on the spillway to dissipate the flow before it reaches the watercourse.  A Headwall with angled Wingwalls and flat apron helps expand the flow in a gradual manner therefore slowing the velocity before it enters the watercourse.  Where the velocity of the peak outflow is in excess of 1.0 m/s then some form of energy dissipation will be required.  Wherever possible high velocities should be addressed within the drainage system, but where this isn't possible advice from the relevant environmental protection agency should be sought.

Althon can offer several options to reduce the velocity before it reaches the watercourse:

Baffle/Dissipation Blocks

Baffle/Dissipation blocks can be cast onto the apron to interrupt the flow and therefore dissipate energy.

Dragons Teeth

Dragons Teeth can be cast at the end of the apron; again this interrupts the flow and dissipates energy.

Stilling Basin

A Stilling Basin is a preferred option from a maintenance point of view but because it normally involves a longer structure land take considerations can preclude its use.

Baffle Chamber

Construction of a chamber directly behind the Headwall and installing a flow control device is a further option we can offer.