Dam walls & slopes
ABG’s Pozidrain geocomposite solution can be specified for dam slopes where overspill capacities are to be increased in accordance with the Reservoir Act in order to cope with a 1 in 1,000 year storm event. In such cases Reservoir Panel 1 engineers require a drainage system to increase the stability of the regraded spillway embankments and to provide drainage to the depth of fill to be placed.
The Pozidrain solution can also double as a seepage leak detection layer to detect any water coming through the clay lining of old embankments. This is a consideration on Victorian dams where the phreatic head pressure from a full reservoir can penetrate minor cracks in the clay lining, leading to a loss of fine clay particles. If this goes undetected, it can eventually lead to full breaches of the header wall. The cohesive nature of the clay cores used in the construction of old dam linings means a traditional coarse granular stone filter design would be ineffective at stopping the loss of fine particles and placing stone layers onto the embankment slopes poses application difficulties.
ABG’s innovative double cuspated Pozidrain 7D240D/NW8 layer with integral upper and lower geotextiles can be specified as an alternative. This provides drainage of rainwater filtering into the drain from above, whilst the underside of the double cuspate allows early identification of any seepage flow to a collection / inspection point so that the integrity of the header wall can be monitored.
Spillway upgrade drainage and detection function
In summary the Pozidrain solution for header wall and dam slope drainage provides efficient filtration without clogging and to prevent piping, alongside adequate flow capacity to channel rainfall and the anticipated seepage during the product’s design life.
Slope Erosion Control
ABG’s permanent and degradable erosion control mats are also available for dam slope construction in order to protect fill from slipping / slump before grass is able to establish.
Erosamats Type 1, Type 2 and Type 4 are biodegradable and offer various life spans and levels of erosion protection. By absorbing the impact energy of rain bombardment and reducing surface water run-off velocities they give the newly establishing vegetation the best possible chance of survival.
Erosamat Type 3 works by providing an interlock for vegetation root systems, better enabling the vegetation to resist high shear/stress situations. It is non-biodegradable and has a design life of 120 years.
Typical Client Profile
- Waterproofing Contractors
- Drainage Contractors
- Water, Wastewater, and Utilities Companies
- Covered Reservoir Engineers
- Structural Engineers
