Flume  Protection  (WFP)  Technology to  Prevent  Failure

Providing Enhanced  Water  Flow  & Power  Capacity  as  well  as  Killing  of  Algae  Growth

Many open channel flumes were built in the past that still carry potable rainwater and snowmelt downhill from high ground mountains to low ground cities, frequently generating very valuable hydroelectric power as they descend.  Many such flumes are single-degree-of-freedom systems a (i.e., no back-up resilience) that can fail suddenly and disrupt the generation of both power and potable water supply to cities, if any one of the following were to occur:

• Design stresses were exceeded due to hydrodynamic forces, earthquake forces, wind forces, falling rocks, floating logs or floating animals,
• Degradation of concrete on the flume’s outside face, for any of several reasons, were to reduce concrete strength below original design stress levels,
• Degradation of steel reinforcing rods on the flume’s inside face, by low pH induced corrosion, were to reduce steel strength capacity or bonding below the original design stress levels.

Correcting all three flume vulnerabilities listed above and thereby preventing catastrophic hazard to sudden structural failure, can be accomplished with the innovative solution presented.  Simply tying back the flume’s two side walls to one another at the top is inadequate, because it requires a horizontal preload applied along the walls that can cause the outside face to be overstressed when empty.
In order to reduce the outside concrete compressive stresses and inside steel tension stresses within a cantilevered flume, a calibrated inwardly directed force must be applied at a height below the high-water line.  Applying such a force within the flume’s water volume could snag debris and collapse the entire structure due to hydraulic drag forces on the debris.  Hence it is optimum to\apply these equal and opposite inwardly directed forces l from outside.
An optimum configuration is to use structural metal or structural concrete to create a channel shaped “[” section with the two short legs vertical and the long middle leg wide enough to horizontally straddle the existing flume wall’s top.  Prefabricated metal or precast concrete can be manufactured off-site and placed in position by truck crane or helicopter.  On-site fabrication with metal or concrete is also an option.

The straddling channel configuration can be used to apply equal and opposite transverse forces to the existing flume wall be inserting hydraulic or mechanical jacks on opposite sides of the flume’s outer walls.  The straddling channels can serve as reaction blocks, both transmitting the desired force as longitudinal walers along the longitudinal flume walls and transmitting force from one side of the flume to the other.  Hydraulic or mechanical jacks can be placed in series with cushioning springs if so desired.
The channel shaped middle leg can be weight-supported by the top of both flume walls with a low friction sliding material between to prevent significant force transfer to the flume at those top edges.
The channel shaped middle leg can be longitudinally continuous along the energy dissipating barrier or intermittent.  If made continuous, or nearly so, it provides the added advantage of blocking sunlight.  Without sunlight algae is prevented from growing, eliminating both frequent flume outages and jet-cleaning operations that can reduce flume longevity.
The channel shaped section can be made of fracture resistant material such as structural steel, light-weight or prestress reinforced concrete, high strength glass reinforced concrete, high strength polymer materials or high strength composite materials.
Once installed the continuous channel cover provides easy vehicular access for both observation and maintenance during foul weather.  It can also provide a support surface for pressurized steel penstocks readily increasing both hydraulic flow and pressure force on rotating turbines to generate much more baseline hydroelectric power without damage to the environment.