State Water Corporation / Detailed Design Services for Fishway at Tyreel Regulator - SWCDoc11/30896

State Water Corporation manages a sub-program titled “Better Delivery of Environmental Water” that contributes to the NSW Rivers and Environmental Restoration Program (RERP), supported by both Commonwealth and State funding. This encompasses a suite of activities including investigations and construction work on fish barriers, leading to recognition that the lower Gwydir area presents substantial ecological and fish-passage issues that require attention.

Copeton Dam Upgrade triggered provisions under Section 218 of the NSW Fisheries Management Act (1994), which empower the Minister for DPI to require provision of fish passage when impoundments are modified. Inter-departmental discussions under the Fishway Offset Process resulted in a decision that, rather than pursuing the option of a fishway at the dam, fish passage should be reinstated at four Gwydir Wetlands sites as an offset, including Tyreel Weir, Tyreel Regulator, Boolooroo Weir and Tareelaroi Weir.

State Water engaged URS to undertake detailed concept designs of fishways at the above structures, as part of Copeton Dam Upgrade fishway offsets. URS completed the works, and their report has been provided with this RFT as background information.

URS recommended:

·  a Full Width Rock Ramp (FWRR) to be constructed along the old Gwydir River bed

·  a bridge to provide access to Tyreel Regulator and Tyreel Weir

·  a migration barrier in the form of low level weir beyond the downstream end of the rock ramp to ensure that the fish migration takes place towards the fishway, not to the regulator

The above report has been reviewed by DPI, and their comments have been highlighted in their letter (attached) dated 1^st Sept 2011. DPI reinforced the following aspects, which were recommended by URS to consider during the detailed design:

·  change the present undershot regulator to an overshot regulator to avoid mass mortalities of juvenile fish due to pressure changes that burst the swim bladder of the fish as they pass under the gates

·  install a trash boom to collect floating debris upstream of the fishway

·  set out an acoustic array monitoring program to determine at what flows large bodied fish are able to migrate upstream using the fishway

Under this engagement, the works will include, but not limited to, all the above aspects recommended by URS and further highlighted by DPI.

The scope of this work is to undertake Detailed Design and Documentations of the proposed full-width rock ramp fishway at Tyreel Regulator as outlined in this brief.

eTendering

16 weeks from the day of approval to proceed,