Warringah Council (Council) invites tenders for the carrying out and completion of excavation works for the Narrabeen Lagoon Entrance Clearance Operation 2016. The works involve the removal of up to 50,000m3 of material from the entrance of Narrabeen Lagoon from the flood tide shoals located to the east and west of the Ocean Street Bridge, as follows:

* West of Ocean St Bridge: up to 25,000m3
* East of Ocean St Bridge: up to 25,000m3

The excavated marine sand is to be transported to Collaroy/Narrabeen Beach by truck for use as beach sand replenishment material. Access to the beach will be via Mactier, Wetherill, Stuart and (opposite) Jenkins Streets, the last being at the northern end of the Collaroy Beach car park. A small amount of this material (approximately 1,100m3) shall be placed along the northern Lagoon shoreline adjacent to the Lakeside Holiday Caravan Park to ameliorate existing erosion in this location. The material is to be spread smoothly to ensure a uniform terrain.

A Review of Environmental Factors (REF) was completed by Cardno in February 2016, and is attached to these tender documents. The REF included the undertaking of bathymetric survey in October 2015, and the preparation of design drawings (Appendix A of the REF) for use by the excavator.

Tenderers are to note that the October 2015 Survey information attached to this RFT is provided for the information of Tenderers only and is not to be relied upon as representing the actual scope of the Work required under the Contract. An initial survey will be undertaken immediately prior to the award of contract commencement of the Work under the contract. Please refer to the Specification for details.

The design of the finished clearance profile aims to remove as much of the accumulated marine sand as possible while aiming to maintain a single well-defined channel, suitable batter slopes, a 10m seagrass buffer and a smooth bed profile. The depth of excavation is designed to limit excavation to clean marine sand, however there is the potential that the sand may contain some rocks. Any excavated sediment containing pieces of rock will need to be sieved, and any rock exceeding the size specification is to be disposed of off-site.

During the works, the entrance needs to remain closed. In extenuating circumstances, such as potential flooding the contractor may be directed by the Superintendent to open the entrance for a period of time, and then close it again. The entrance will need to be opened at the completion of excavation.

Tenders close at 2pm on Tuesday 24th May 2016 and must be fully received by this time.