The main lessons learned from this project are centered around:
- Alliance contract
- Risk assessments
- Work method
- Turbidity limits
- Adaptive Management Strategies Strategic and Operational Objectives
This project had a high risk profile related to the sensitive environment, but this risk could be mitigated in collaboration with the contractor. To ensure input of highly qualified construction expertise, early contractor involvement is necessary and can be achieved with an alliance contract.
This project proved the effectiveness of early contractor involvement under this type of contract. The input of the contractor was mainly related to the work methods and input to various studies. The results of this early contractor involvement were incorporated into the SEES and EMP, which were both part of the environmental approval process for the Channel Deepening Project. Boskalis’ technical solutions and innovations were all critical in achieving the desired depths and expansion, and ensuring the Bay’s unique natural environment.
Main lesson learned is that early contractor involvement and modern contracts contribute to a higher quality of the construction works. In this case the combined efforts of the Client PoMC and the contractor in an Alliance Contract led to nearly full compliance and successful completion of the project.
The risk assessment was a very open process in which the risks were quantified, so that a trade-off could be made between different assets. The government has to provide guidelines on which impact is still acceptable and which is not. This type of risk assessments cost quite a lot of time, but this ensured the accuracy of the process. Another advantage was that this enabled a better informed and more effective communication with the public.
This project showed that work method adjustment can be a very good instrument to mitigate effects. This includes controlling and managing the measures taken, hence the impact. For this project the work method was adjusted to reduce the impact of turbidity, to control rock fall at the entrance and to remove the contaminated material.
It is very important that the environmental limits such as turbidity limits are based on the local situation. In this project, the limits were defined considering the local flora and fauna, such as local meadows of seagrass. The model-based approach yielded realistic and workable criteria which worked very well to manage the turbidity levels. Due to the 6-hourly EWMA the signal was smooth and short peaks were less important, which made process management more comfortable. Two response levels were defined to manage the dredging process and to make sure that the actual turbidity limits would never be reached. These two response levels worked excellent and the turbidity limits were never exceeded.
Background turbidity remained an important issue, which was still not completely covered. Even in this project where extensive research was conducted, including the background turbidity, the distinction between background turbidity and dredging-induced turbidity was sometimes very small. To get a better understanding of the background turbidity one has to understand and know the system thoroughly. Therefore much attention must be paid to the baseline study in order to have sufficient information about the background turbidity, especially because it depends on variable and dynamic aspects, such as season, weather etc.
In order to achieve a high data capture rate, the buoys need to be actively maintained. They should be taken out of the water at least once per week for cleaning and the data should be regularly verified and calibrated.
The monitoring for validating the model proved very useful. Data are indispensable to validate the model, like it is for other parts of this project, such as the relation between mg/l and NTU, and that between turbidity and light attenuation.
Reviewing the bay-wide monitoring scheme once every half year seemed a good frequency for the ecological response. The review should fit the asset monitored. The impact on a coral reef, for instance, will be more direct than the impact on penguins. The bay-wide monitoring program served as an extra to assess the status of the ecology of the bay, but it is not suitable to manage the dredging process from a turbidity point of view.
Communication is essential in environmental management and needs to be addressed explicitly in the EMP. All procedures should be clearly defined, correct and communicated in case of irregularities. The client should inform the public and the contractor should assist in this, mainly by informing the client. The procedures for the internal communication (between client, contractor and government) should be clearly defined, for irregularities as well as the regular process. This requires a transparent and open process. The PoMC did a very good job in communicating with the public. For example, they held press conferences every week, even if no-one showed up. They could do so, because they were kept well up to date about the processes by Boskalis.
Communication should also include the progress of the construction works. This is where the contractor can play a major role, as he has all the information regarding progress. Therefore he should provide the Client with this information via transparent and open communication.
Adaptive Management Strategies
Lessons on Adaptive Management are tabled for the 3 control& monitoring programs, along the Operational Objectives and other elements of the Frame of Reference.
Authorities Independent Control & Monitoring
|Strategic Objective||Operational Objective||Quantitative State Concept (QSC)||Limits||Spatial control zone||Evaluation Procedure|
|SEES||Legislation:Coastal Manangement Act 1995 (Victoria)Environmental Protection Act 1970 (Victoria)Environmental Projection and Biodiversity Conservation Act 1999 (Commonwealth)National Parcs Act 1975 (Victoria)Wildlife Act 1975 (Victoria)||–||–||–||State government: approval of EMP. In case of a major revision of the EMP approval was required by the Depart of sustainability and Environment (DSE), and PoMC would seek advice whether these revisions require approval by the Commonwealth.|
Next to the EMP the Commonwealth was present by the management reviews. The evaluation was in form of audits
Long term – Owners Feedback Monitoring
|Strategic Objective||Operational Objective||Quantitative State Concept (QSC)|
|Spatial control zone||Evaluation Procedure|
|SEES: PoMC Environmental Policy: Port of Melbourne Corporation (PoMC) is charged with providing the strategic management of the operation and development of the Port of Melbourne and to ensure that this is done in an economically, socially and environmentally sustainable matter.||The Channel Deepening Project Team is commited to ensuring the project is undertaken in accordance with the following principles and objectives regarding the environment: minimise hard to the environmental through full compliance with the CDP Environmental Management Plan (EMP).||Baywide monitoring program: To support the management and mitigation measures, such as turbidity monitoring, a suite of Baywide monitoring programs have been developed to provide broader information on the status of key species, habitats and ecological processes in the bay. A total of nine programs have been developed:SeagrassWater qualityNutrient cyclingContaminants in FishAlgal bloomsLittle PenguinsFish Stock and RecruitmentPlume Intensity and ExtentRamsar Wetlands – Key coastal and intertidal vegetation communities||–||Baywide||The baywide monitoring programs are subject to an evaluation to identify any refinements and if required will be resubmitted to Victorian and Commonwealth regulatory agencies for approval.|
Short term – Contractor’s Monitoring
|Strategic Objective||Operational Objective||Quantitative State Concept (QSC)||Limits||Spatial control zone||Intervention Procedure||Evaluation Procedure|
|It is the policy of Boskalis that all employees, including those of subcontractors and suppliers, execute their work safely and under healthy conditions, with approporiate concern for the protection of the environment.||The ultimate objective of the policy is zero incidents with environmental impact.||Light attenuation through turbidity||Turbidity limits||Continuous monitoring of turbidity at conformance locations.Monitoring during dredging activities and for the period after dredging has ceased that turbidity remains above background concentrations (likely to be in the order of weeks after completion of dredging)Monitoring of turbidity at key sites between assets and dredge operations to provide additional data on the turbidity plumeMonitoring of major inputs for turbidity not related to the project||Response levels provide an early warning to enable management action. If the response limit is exceeded the activity is modified or suspended. Also the cause(s) are identified and assessed.||–|