Mr WOOD - 2005-02-10
In this just released volume, one of about 12 great whopping books we received the other day, called Supplementary Information Supporting the Development Application for Marine Infrastructure Works, Darwin City Waterfront, I asked about the removal of contaminated mud from Kitchener Bay. In reply, the authors say that it is proposed to dump the mud from Kitchener Bay into the East Arm Port sediment retention ponds.
Will this mean that any proposed development of that area at the East Arm Port will now not go ahead? If so, how long will this area of the port be out of action? Will this reduction in the use of the port have any financial implications, and has that been costed in as part of the government’s contribution to the waterfront project?
ANSWER
Madam Speaker, I thank the member for his question. There is a lot of detail in that question and maybe I will have to get back to you on some parts of it. With regard to the part of the question about general issue of dredging of the Kitchener Bay mud and its disposal at East Arm Port, I can answer. As you understand, dredging is necessary for the construction of the sea wall and some of the other associated features of the waterfront project. It is an important part of the development, and will allow things like the permanent water body and some of those water sport activities to take place. It was first covered by the all-encompassing environmental impact study, which was completed by URS on behalf of government and, subsequent to that, further work has been done to take into account the specific proposals offered by the Darwin Cove Consortium. This has led to an ecological risk assessment being made of the method proposed for both dredging and soil disposal.
There is about 630 000 m3 of mainly silt and clay to be excavated. The turbidity and sediment re-suspension will be limited to the vicinity of the cut ahead and when the dredge anchors. After mixing to dilute any surface level contaminants, the slurry will be pumped, via a pipeline, to a contaminant area at East Arm Port, with discharge into an array of settlement ponds. This disposal method is similar to the already proven and environmentally acceptable practice used for the disposal of dredged material for Stage 2A of the East Arm Port. The sediment will be allowed to settle, followed by release of tail water to Darwin Harbour. Water quality will be monitored and discharged in accordance with the turbidity criteria that was adopted for the East Arm Port Stage 2A development.
A detailed site contamination investigation and field geo-technic investigation examined the potential for acid generation from the shallow marine sediments at Kitchener Bay, and no environmental concerns regarding acid sulphate soils are foreseen. The environmental risk assessment concluded that the ecological impact on Darwin Harbour of the proposed dredging and spoil disposal is low. Dredging is expected to be completed about six months after financial close. I will let you know some of those other details as soon as possible.
Will this mean that any proposed development of that area at the East Arm Port will now not go ahead? If so, how long will this area of the port be out of action? Will this reduction in the use of the port have any financial implications, and has that been costed in as part of the government’s contribution to the waterfront project?
ANSWER
Madam Speaker, I thank the member for his question. There is a lot of detail in that question and maybe I will have to get back to you on some parts of it. With regard to the part of the question about general issue of dredging of the Kitchener Bay mud and its disposal at East Arm Port, I can answer. As you understand, dredging is necessary for the construction of the sea wall and some of the other associated features of the waterfront project. It is an important part of the development, and will allow things like the permanent water body and some of those water sport activities to take place. It was first covered by the all-encompassing environmental impact study, which was completed by URS on behalf of government and, subsequent to that, further work has been done to take into account the specific proposals offered by the Darwin Cove Consortium. This has led to an ecological risk assessment being made of the method proposed for both dredging and soil disposal.
There is about 630 000 m3 of mainly silt and clay to be excavated. The turbidity and sediment re-suspension will be limited to the vicinity of the cut ahead and when the dredge anchors. After mixing to dilute any surface level contaminants, the slurry will be pumped, via a pipeline, to a contaminant area at East Arm Port, with discharge into an array of settlement ponds. This disposal method is similar to the already proven and environmentally acceptable practice used for the disposal of dredged material for Stage 2A of the East Arm Port. The sediment will be allowed to settle, followed by release of tail water to Darwin Harbour. Water quality will be monitored and discharged in accordance with the turbidity criteria that was adopted for the East Arm Port Stage 2A development.
A detailed site contamination investigation and field geo-technic investigation examined the potential for acid generation from the shallow marine sediments at Kitchener Bay, and no environmental concerns regarding acid sulphate soils are foreseen. The environmental risk assessment concluded that the ecological impact on Darwin Harbour of the proposed dredging and spoil disposal is low. Dredging is expected to be completed about six months after financial close. I will let you know some of those other details as soon as possible.
Last updated: 09 Aug 2016