The Sydney Water Catchment Authority (SCA) has deployed a new wireless communications system through its six kilometeres of tunnels and shafts at Warragamba Dam. The new network will provide communications to staff in the absence of cellular coverage.

The agency manages and protects Sydney's catchments and supplies bulk water to Sydney Water and local councils which in turn distribute it to households and businesses.

SCA operations manager Brian Simmons said the system, dubbed Kirk 3000, has increased safety by maintaining contact with staff as they work across the site's dam network of tunnels.

"Mobile phones, pagers and other portable devices don't work inside the dam access galleries," Simmons said.

"We needed to be able to communicate from anywhere in the dam.

"It is one of the most significant enhancements to safety to the site. It is a means to keep in touch with staff so we can better manage any evacuation of staff should it ever be required."

The project started early last year and went live after about six months which included a tender process and limited testing and tuning.

About 20 handsets -- purchased for staff and contractors -- can be used across the entire site precinct, which is the largest urban supply dam in the country.

Simmons said it considered a few other options including leaky wire, but was limited because of the unique architecture of the site.

Previously, the authority used a fixed PBX system to communicate with staff.

Frank Kelleher, project manager for integrator O'Donnell Griffin, said the deployment is the largest of its kind in the country.

"No additional engineering was required, [however] access to existing conduit systems was problematic," Kelleher said.

Existing cables in the dam conduits had to be replaced without disruption operations.