Over the course of time, dam walls can suffer from deterioration or even possibly sustain damage from natural disasters such as floods or earthquakes. In order to prevent such catastrophes from threatening nearby communities and the environment, it may be necessary to carry out partial demolitions as part of essential maintenance.

At Hazelmere, the existing spillway crest, piers, lintel beam and bridge decks were demolished. Image credit: Jet Demolition

At Hazelmere, the existing spillway crest, piers, lintel beam and bridge decks were demolished. Image credit: Jet Demolition

In other instances, reducing the height or capacity of a dam wall could be necessary to restore a river or waterway to its natural state or accommodate changing land-use patterns. Older dams may have outlived their original purpose or been rendered obsolete by advancing technology. Here it could be more cost-effective to demolish a dam wall than to maintain it.

Hazelmere Dam saw the compilation of specific demolition-control guidelines. Image credit: Jet Demolition

Hazelmere Dam saw the compilation of specific demolition-control guidelines. Image credit: Jet Demolition

Refined blasting techniques have been developed specifically to retain the structural stability of dams themselves, with no wasted effort. Such projects call for highly controlled, cautious, partial demolition techniques. “Our work on large water-retaining dams consists of some of the most important projects we have undertaken to date,” comments Jet Demolition contracts and project manager Kate Bester.

Jet Demolition has developed new blasting techniques to retain the structural stability of dams. Image credit: Jet Demolition

Jet Demolition has developed new blasting techniques to retain the structural stability of dams. Image credit: Jet Demolition

Rehabilitation of dam walls usually requires demolition of redundant portions of monolithic blocks and associated concrete structures. Dynamic energy imparted by the demolition process has the potential to cause damage to concrete located just across the demolition boundaries and beyond. While it is essential to avoid damage to remaining concrete, it is also important to carry out the demolition works in a productive and cost-effective manner.

Informed and judicious selection of demolition methods and their application techniques can be vital to a controlled and productive project, which is where the company’s extensive experience stands it in good stead. Dam demolition calls for meticulous planning and execution to minimise the environmental impact, especially releasing debris and sediment downstream.

Demolition techniques range from controlled explosives to cutting or breaking the dam wall into sections so the material can be removed. Following demolition, the site can be restored to its natural state or repurposed for recreational use or hydroelectric power generation.

The Full Supply Level (FSL) of Hazelmere Dam was raised by replacing the original Radial Arm Gate design with a Piano Key Weir. Image credit: Jet Demolition

The Full Supply Level (FSL) of Hazelmere Dam was raised by replacing the original Radial Arm Gate design with a Piano Key Weir. Image credit: Jet Demolition