NSW Public Works has a strong history of delivering dams projects.  Our professional teams work with a coordinated, client focused approach across all aspects of projects.  In the on time and within budget delivery of Chaffey Dam Safety Upgrade for Water NSW (formerly State Water), NSW Public Works managed the contract management, including construction surveillance, site inspection and audits.

The outcome was an auxiliary spillway to pass a flood with an AEP of 1:450,000 which now eliminates the risk of high inflows surcharging the storage and subjecting the dam structure to excessive stress.  Chaffey Dam structure consists of clay core rock-fill embankment with a combined morning glory spillway and outlet concrete structure.  The Dam structure is 54m high and 430m long and storage capacity of 62GL at full supply providing town and irrigating water supplies, flood mitigation and drought security to the Tamworth Region.

Excavation of a new auxiliary spillway through the left hand abutment ridge line, including blasting and excavation of 300,000 m³ in hard rock and excavation of 100,000 m³ in soft rock was carried out as part of the upgrade which also included the construction of Fuse Plug within the floor of the spillway channel including foundation preparation, dental concrete, reinforced concrete sill and earth fill zoned embankment.  Engineered terraced hard rock and soft rock stockpiles of excavated material from the spillway cut was also part of the construction.