Partner charter under pins giant Sydney project
A joint venture to rehabilitate Sydney's major sewer outfall is a model for successful partnering on a major project, reports Hugh McGinley, Business Development Manager at Earth Tech
Rehabilitating Sydney’s largest sewerage system, serving approximately 1.5 million of the city’s 4 million residents, is believed to be the largest of its type ever undertaken in Australia. It is certainly the most challenging sewerage project ever undertaken by Sydney Water.
The Southern and Western Suburbs Ocean Outfall Sewer (SWSOOS) traverses over 50km from Campbelltown in south west Sydney through to Malabar Sewage Treatment Plant on the coast and transports around 40% of the total sewage flow within Sydney Water’s area.
The trunk network system was constructed in sections from 1892 to the 1970s and has suffered from concrete corrosion caused by H2S attack. Rehabilitation is a major component of the Malabar System / SWSOOS Trunk Risk Reduction Program (TRRP). Running for 22 years, this works programme has an estimated overall cost of around US$377.5 million.
The project, a joint venture of Earth Tech, McConnell Dowell and Tyco Water Pipeline Renovation (EMTJV) was started in July 2003 and involves:
l implementation of corrosion and odour control
l silt removal
l aqueduct repairs
l rehabilitation of lead-contaminated soil near aqueducts
Sydney Water aims to restore the structural integrity and hydraulic capacity of the SWSOOS, thus reducing the frequency of overflows into the environment. The work entails silt removal, hydro demolition, surface preparation, assessment of the remaining reinforcement, replacement of reinforcement (where necessary), concrete reinstatement and application of a chemical-resistant epoxy lining.
This includes access to, and rehabilitation of, over 10km of degraded reinforced concrete box section (50,000m2 in surface area) in a hostile, confined environment.
The SWSOOS APB is split into three distinct sites (see aerial photograph) comprising single (Site 3), double (Site 2) and triple barrel (Site 1) configurations in the different sections. These generally rectangular barrels vary in dimensions from approximately 2.9m wide x 2.0m high to 4.9m wide x 2.4m high.
In July 2003, Sydney Water awarded a three-year contract to the joint venture of engineering managers Earth Tech, civil constructors McConnell Dowell and rehabilitation specialists
Tyco Water Pipeline Renovation (EMTJV).
The project team developed a Partnering Charter from a set of ‘partnering principles’ that aligned the objectives of Sydney Water and EMTJV, they agreed to:
l form teams that would work with jointly developed performance indicators
l seek agreement on sharing risks and benefits
l set a framework for working together openly, fairly and with a ‘best for project’ attitude
The compensation model for the contract was developed along similar lines and is structured around four key components:
1. A schedule of rates, including direct costs for labour, materials and equipment, and excluding overheads and profit, for a known scope of work.
2. A fixed management fee, including the cost of work and independent of the quantities required to perform the work, fixed for the term of the contract. The fixed management fee consists of a lump sum amount.
3. A contract contingency pool that allows for payment for the impact of external events such as delays due to high flows, with any savings shared between Sydney Water and EMTJV,
4. Due to the sensitive nature of the contract, a risk-reward pool assigns profit to the joint venture based on its actual performance compared to pre-agreed targets in four non-cost Key Performance Areas: time, safety, environmental impact and community/stakeholders. These indicators are aligned to Sydney Water’s wider project objectives.
The contract, established on partnering principles, ensures excellent working relationships, good communications and respect between the parties. The follow up and close out of actions to meet individual needs within agreed timeframes is paramount to project team members. priorities.
The complex worksite, material requirements and project timeframes have presented EMTJV with a number of challenges.
Live flow conditions
In Sites 1 and 2, where the sewer is multi-barrelled, flows can be diverted from where work is being carried out into adjoining barrels. In Site 3, however, the barrels merge into a single conduit, with the flows being too large to divert easily.
In this situation, the rehabilitation work has to be carried out in live flow conditions. Given this hostile environment, extreme measures have been taken to ensure workforce safety and safe work methods have been developed through the Safety Management Plan.
The worksite passes through a number of commercial and residential areas, and both for safety reasons and community relations, a ventilation system that eliminates odour problems without creating access issues was developed.
A sophisticated flow monitoring system within the SWSOOS catchment is employed to ensure early warning of high flow conditions in the sewer. This allows suspension of works in any location, removal of flow isolation to the diversion barrel and prevention of possible overflows from the system.
Due to the proximity to residential and commercial premises of Sites 1 and 3, the Environmental Management Plan eliminates issues regarding noise, light pollution, site traffic, access etc.
Community issues are promptly addressed through the Community Relations Plan which not only sets out required response times to close out any concerns raised by residents or stakeholders, but promotes engagement with the community, such as EMTJV’s sponsorship of local sporting clubs.
The sheer scale of the rehabilitation and lining work to be executed, in a long ribbon-type site, necessitated careful planning for the delivery of materials to the work face.
Specialised plant and equipment, such as mini-Bobcats and epoxy spray pumps and heads, are being used to counter constraints such as limited access points.
The epoxy material itself has to be mixed and maintained at a pre-set temperature to allow its workability for the long distances it has to be pumped along the sewer barrel for application. Following application, rigorous testing of the finished lining is carried out to ensure Sydney Water’s performance criteria are met.
Sydney Water have expressed satisfaction with the implementation of the project, Project Manager, Ashok Bajaj said, “This is one of the most important projects for Sydney Water in recent times. Working with a partnering approach to the contract has overcome many of the problems that can arise with more traditional forms of project delivery”.
Contact: Earth Tech
Aerial photograph courtesy of Sydney Water. Other photos courtesy of Earth Tech Inc.