Cullendulla Sewer Rising Main Realignment
Project: Realignment of the existing sewer rising main from Long Beach to Surfside
Cost: $3.178 million (awarded contract price) included in our 2018-19 Capital Program
Timeframe: September 2018 to May 2019
The project involves installing a sewer rising main beneath Cullendulla Creek Nature Reserve from Long Beach to Surfside.
The pipeline will replace the existing sewer pipe that has become exposed on Cullendulla Beach due to encroaching seas.
The new pipe will be located inland, safely away from the shoreline, and pass deep beneath Cullendulla Creek.
The route will extend from the existing depot at the east end of Myamba Parade, Surfide, 1.2 kilometers to near the existing pump station at Nuyen Place, Long Beach.
The HDPE pipe will have an internal diameter of 300mm and an external diameter of 450mm and be installed using horizontal directional drilling technology. This method will prevent any disturbance to Cullendulla Creek Nature Reserve and Cullendulla Creek.
The contract has been awarded to Dunstans Construction Group Pty Ltd and the works will be overseen by Public Works Advisory on our behalf.
The old sewer pipe will be removed once the new main is operating.
Access to Cullendulla Creek Nature Reserve will not be affected and all walking tracks will remain open during works.
- The contractor, Dunstans, is working to flush, decontaminate and decommission the old sewer pipe.
- Once the new sewer pipe is connected to Council’s existing infrastructure at either end of the project, work will begin to remove the exposed sections of the old sewer pipe from Cullendulla Beach.
- Both Surfside and Long Beach worksites will then be fully restored by the contractor.
- The major milestone of installing the 1.2km of pipe went ahead as scheduled on Monday 15 April.
- Once installation began any interruption would increase the risk of the pipe becoming stuck, which would be catastrophic to the project. Therefore the work continued through the day and night until the pipe was fully installed.
- The pipe was pulled through the borehole without a hitch and work was complete by 1.30am; well short of the 6.30am estimate provided by the contractor.
- The drilling machinery is now being removed from site and the contractors will return after Easter to tie in the new pipe to Council's existing infrastructure.
- We know this has been a long and noisy process for nearby residents, and the community has been fantastic considering the circumstances. We genuinely appreciate residents’ patience and understanding for what is a vital project.
- The three huge 400m strings of 450mm diameter pipe are ready to be pulled through the bore hole.
- Once the bore hole is fully prepared the first pipe string will be connected to the drill head and pulled back through the hole from Long Beach toward Surfside.
- When the first length of pipe is in the ground the second string will be welded to it and pulled through. The process will be the same for the third string.
- Once the full 1.2km pipe is installed the contractors will tie it in to the existing sewerage infrastructure at either end of the alignment.
- Dunstans have finished welding together the lengths of pipe at the Long Beach site. The three 400m strings of pipe have been pressure tested and are ready for installation.
- The connection to the pilot hole from Long Beach has finally been achieved after progress was hindered by the presence of rock deep beneath Cullendulla Creek.
- The bored hole is being reamed to increase the diameter and ensure there are no impediments.
- At the contractor’s request we have granted permission to work on weekends to ensure the pipe is installed as quickly and efficiently as possible.
- Drilling works have resumed in Surfside to connect the bore hole to the Long Beach side.
- Once connected, the hole will be reamed out to a diameter of 660mm in preparation for pulling the strings of pipe through.
- After significant delays, the Maxi HDD rig arrived at the Surfside site and started drilling a 311mm diameter hole following the hole previously bored by the smaller drill rig.
- The delivery delay has caused disruption to the contractor’s schedule of works. In order to install the 1.2km pipe as soon as possible, drilling works continued over the weekends in December.
- The contractor has requested to resume work after the Christmas break, on 7 January, working Monday to Friday only.
- Over on the Long Beach side, the short lengths of pipe are being welded together to create three 400m strings.
- Each string of pipe will undergo pressure testing before it is installed.
- Once the drill head reaches Long Beach the pipe will be connected and pulled back through the bore hole to Surfside.
- Due to the proximity of the entry and exit points to the creek and nature reserve a 762mm diameter steel casing is being utilised to minimise the impact on the environment.
- The casing will significantly reduce the risks associated with any drill fluid release into the creek or reserve.
- An air hammer has been used to install approximately 30m of casing at the Surfside end and 50m at the Long Beach end penetrating into the harder formation below the alluvial layer.
- The drill rig has been moved to Long Beach and has drilled and reamed the 250m pilot hole from the eastern end.
- A larger drill rig will take on the massive task of connecting the two pilot holes.
- The head of the drill will be connected to the drill rig by numerous steel rods and carefully steered from aboveground by a trained operator.
- The new HDPE pipes lengths are being butt welded together to form three 400m lengths. The pipe welder is powered by a diesel generator which is causing considerable noise in the Long Beach area. We anticipate the contractors will finish the welding work in early December.
- Compounds have been established at either end of the new sewer rising main in Surfside and Long Beach.
- Drilling works are well underway with a relatively small diameter pilot hole drilled 250m horizontally 30m underground from the Surfside end heading toward Long Beach.
- The hole was then reamed to a larger diameter of 355mm.
- The new HDPE pipe has been delivered to Long Beach.
For more information about the project, please contact our Water & Sewer Senior Technical Officer, Richard Dixon:
- T: 4474 1000
- E: Council