MidCoast Water has produced a new design that has the potential to reduce the injury risk associated with the handling of traditional manhole covers.
MidCoast Water is a county Council that was formed following reforms to the New South Wales electricity network in 1997. The new council took on the staff, assets and former responsibilities of three authorities, including NorthPower’s water supply systems, Greater Taree City Council’s sewerage network and Great Lakes Council’s water and sewerage facilities.
Covering some 7,000 square kilometres, Council delivers water and sewerage services to 35,000 households across the Manning and Great Lakes communities of New South Wales.
With 14,000 manholes in its jurisdiction, MidCoast began designing its lightweight, lockable and watertight manhole lid cover in 2006 and expects production to begin this month.
Developed by a project team of MidCoast Water staff, in conjunction with a polyethylene manufacturer, the innovative design eliminates a number of risks associated with traditional manhole lids.
Weighing around 38 kilograms, traditional covers are heavy and pose a manual handling risk for staff.
MidCoast Water’s Development Inspector, Lance Fletcher, said traditional manhole covers are lifted by two people using lifting rods, which are placed under steel lugs imbedded in the concrete lids.
“These lugs have a tendency to rust, reducing the availability to only one of the two lugs to perform a lift,” he said. “The new covers weigh only 12 kilograms, will fit into existing manholes and can be manoeuvred into place by one operator.”
Lance Fletcher said the new covers are watertight and will reduce infiltration into sewer systems.
“Traditional manhole covers are a major cause of water infiltration during a wet weather event, increasing flow by three to ten times the average dry weather flow,” he said. “This often overloads the network and causes a surcharge of sewage, resulting in additional call outs for our staff. A reduction of stormwater in the sewerage network will result in a more efficient effluent treatment process, lower energy consumption and improved environmental outcomes.”
The heavy weight and handling difficulties of traditional manhole covers generally prevents public access, but due to its lightweight, the new polypropylene cover requires a locking mechanism.
Lance Fletcher said the key to the locking mechanism is conveniently designed into the lifting device.
“This eliminates any unauthorised entry into a potentially dangerous environment and also eliminates the environmental risks posed by illegal dumping of materials into the wastewater system,” he said.
The new covers include a non slip surface, reducing the potential for public liability slip and fall claims and the polypropylene material is also resistant to corrosion caused by hydrogen sulphide gas (H2S).
Traditional concrete manhole covers are vulnerable to the H2S produced during the biological process of sewerage breakdown, which causes corrosion of the lids.
Lance Fletcher said Council will gradually replace all its existing manholes with the new lightweight ones.
“We aim to install around 250 to 500 per year, initially in wet areas, such as creeks and flood prone areas,” he said.
For further information contact Lance Fletcher on (02) 6569 7519.
