The Glenelg to Adelaide Parklands Reuse Scheme is a $A74.5 million project providing extra treatment facilities, a 10 kilometre pipeline from Glenelg to Adelaide’s CBD, and approximately 30 kilometres of pipeline around the Parklands. It will enable about 3.8 billion litres of treated water to be recycled annually.
In addition to supplying existing customers, the project will provide a minimum of 1.3 billion litres each year to irrigate the Adelaide Park Lands. This landmark project will provide a sustainable long term solution for watering the Park Lands and can provide opportunities for the development of additional recycled water initiatives.
This project is being delivered by the CityGreen Alliance, which includes SA Water, United Water, Leed Engineering and Construction, Leighton Services, and Guidera O’Connor.
Trenchless takes off
Shoota Trenchless Drilling is responsible for the thrust boring and pipe jacking of GRP for the CityGreen Alliance. The project began in October 2008 and will be completed in April 2009.
The trenchless aspect of the project comprised five thrust bores (auger bores). Shoota operated two McLaughlin borers; one with a diameter of up to 900 mm and the other capable of a
1,350 mm diameter. On average, each bore took approximately seven days to complete, taking into consideration delays for wood, running sand and other obstacles encountered by the team.
Launch pit
The launch pit was dug by Shoota’s 22 tonne excavator. Each shaft was approximately 10.5 metres long and 2.5 metres wide and varied in depth from 2 – 5 metres. Some shafts were benched out metre by metre. However, if the company could not bench out, a shoring box was put in the shaft. Each shaft took approximately half a day to prepare for drilling.
Ground conditions
The ground conditions have varied from running sand at Taply Hills Road to clay. At Taply Hills Road, the running sand meant that bore had to be spare point.
Bores
The Anzac Highway road crossing was 18 metres in length. An old water main was struck, which had to be cut out of the way. The company also completed two 42 metre bores and a 72 metre bore on Peacock Road in Adelaide City, which saw 30 metres drilled in the first day.
The Taply Hills Road crossing, a main highway, was a 56 metre bore near the Adelaide Airport. The bore was completed at night, over durations of six hours per night. This bore was quite challenging as the airplanes disrupted work. The airplanes were combined with a number of other obstacles, such as old wooden sleepers that were drilled into. Due to the nature of the work, the Taply Hills Road bore was completed in two weeks.
Pipe jacking
Shoota also used a pipe jacking station with a Volvo power pack. The team pipe jacked one shot of 80 metres of steel casing.
Challenges
There were a number of challenges to overcome in the successful completion of the trenchless aspects of the Glenelg to Adelaide pipeline. Shoota Trenchless Drilling General Manager Steve Schut said that the limestone clay caused a lot of friction on the pipe. “In regards to the proximity of the airport, airport safety officers were present at night in order to communicate with the traffic tower so we knew when the boom of the excavator had to be lowered for incoming and out going planes.” Mr Schut said the continuous downtime with the planes taking off and landing was understandable. Shoota had limited hours of work with only a six-hour window at the airport, combined with the disruptions of the planes. Mr Schut said “The airport personnel were very co-operative with us.”
Shoota worked with the drilling department of Leed Engineering and Constructions to complete the works. Shoota has previously completed drilling projects such as the Bendigo recycled water pipeline, Gippsland Water Project, the Goldfields Superpipe and the Casterton-Coleraine pipeline.
Current construction report
Construction of the new recycled water treatment facility at the Glenelg Wastewater Treatment Plant is now underway. The first stage of the underground pipeline in Adelaide Airport Limited land has been completed, and installation of the trunk main pipeline in the suburbs of Netley and Marleston is ongoing. A CityGreen Alliance construction team is currently installing the ring main pipeline in the eastern and southern Park Lands, and a second team is working in the northern Park Lands, within the North Adelaide Golf Course.
The underground pipeline is being constructed at a number of locations concurrently in West Torrens and the Park Lands to ensure timely construction completion. Completion of the project, with water in the Park Lands for irrigation, is planned for mid-2010.
Australia’s water future
The South Australian Minister for Water Security Karlene Maywald said “Water is one of our most precious resources and it needs to be carefully managed to meet the needs of all South Australians – now and in the future.
“On completion, the project will deliver a sustainable supply of recycled water for the Adelaide Park Lands and Adelaide City. The project will provide ecological, social and economic benefits for government, business and the community.”