Chatham Rock Phosphate Marine Consent Application. P Kennedy - Environmental Impact Assessment Evidence Summary

Transcription

1 Chatham Rock Phosphate Marine Consent Application P Kennedy - Environmental Impact Assessment Evidence Summary

2 My evidence and this summary cover the following matters: Seabed and sediment Discharge and toxicology Sediment plume modelling Effects of TSS and sedimentation Effects thresholds Effects on fisheries Effects on marine mammals Effects on seabirds Effects on seabirds Effects on ecology Corals and exclusion areas Radioactivity Recolonisation and colonisation trials Monitoring November 17,

3 Seabed and sediment chemistry Seabed sediments in the MLA have been described. Sediments are oxic to sub-oxic comprising silty glauconitic sand over chalk. Expert caucusing (Toxicology and Water Quality Group) commented on the lack of information outside the MLA and supported more information on redox state. Recording the redox state and providing on-going characterisation of sediments (e.g., for carbon, nutrients and trace elements) will be a part of proposed ongoing monitoring and characterisation. Characterisation will be undertaken when mining block cores are collected. These data form the basis for confirming that discharge water quality does not change. Ongoing samples of sediment will be collected and characterised as part of the monitoring programme. The draft monitoring section of the EMMP provides additional detail. November 17,

4 Discharge and toxicology Characterisation of the discharge using a range of elutriate tests, has shown that very low amounts of dilution are required after discharge to ensure toxicity should not occur. Additional modelling was undertaken to provide improved data on dilution of the discharge. The modelling showed that there was significant dilution close to the discharge. The Toxicity and Water Quality Expert Caucus Group concluded that to confirm the low toxicity in the tests undertaken new toxicity tests using elutriate produced using fresh sediment should be carried out. This has been included in the draft EMMP and the proposed consent conditions. The Toxicity and Water Quality Expert Caucus Group also recommended that some additional tests be carried out if species from the Chatham Rise were available for toxicity testing. The proposed conditions include additional toxicity testing using species from the Chatham Rise (presuming they are suitable for testing). Additionally, the Toxicity and Water Quality Expert Group recommended that the quality of the discharge be monitored. The draft EMMP and the proposed conditions include a discharge monitoring programme. The programme will CRP propose that this would occur on board the vessel but within the sinker pipe system. November 17,

5 Sediment plume modelling The Sediment Modelling Expert Caucus Group examined the inputs to the plume modelling. The inputs included the grain size data and the particle settling velocities. They concluded that the model outputs were conservative and as such the distances and TSS concentrations predicted were likely to be smaller. Several witnesses mentioned changes in grain size through grinding the separation process does not involve grinding. The Expert Caucus Group asked questions about managing how much chalk is included when mining seabed. A condition has been proposed to assess depth to chalk (by undertaking coring) in each mining block before mining. This will assist in adjusting the depth of sediment dredging. November 17,

6 Effects thresholds Total Suspended Solids The lowest TSS threshold identified was 2-3 mg/l: for some fish species avoidance was predicted and it was likely that sediment adhesion might affect some fish egg buoyancy. Other relevant thresholds were identified, such as 100 mg/l for effects of TSS on benthic biota. Effects include both concentration and duration (e.g., Marlin threshold of 100 mg/l for a period of 1 month). Key commercial species do not spawn or do not have key spawning areas within the MLA or influence of the predicted plume area. The plume modelling has predicted the distances (and area) and time at which TSS concentrations are likely to occur. The response to additional information to questions 3,4,5 and 7 provided plots of the % time of 10 mining cycles) that a given concentration (e.g., 10, 30, 50, 100 mg/l) would occur. The mining plume monitoring will identify where the 50 mg/l threshold occurs. This will be compared to the modelling predictions. From this information the expected location of the 2-3 mg/l threshold can be predicted. This can also be compared to the field data. The 50 mg/l can be measured with more certainty than 2-3 mg/l. November 17,

7 Effects on fisheries Within the MLA, the plume is predicted to cause avoidance of mobile fish who have low tolerance for TSS. Plume modelling indicates no direct interaction with areas of commercial fishing. Modelling of the effects of loss of fish within the MLA on stock of the three key commercial fish did not reveal any significant effects. The Toxicology and Water Quality Expert Caucus Group noted that there was no baseline trace element data for quality of key commercial fish and recommended that it be gathered. CRP has proposed monitoring of trace elements and radionuclides in ling and hoki in the proposed conditions and in the monitoring section of the draft EMMP. November 17,

8 Effects on seabirds The Seabirds Expert Caucus Group concluded that there was a lack of comprehensive data of seabird occurrence, abundance and use of the Chatham Rise. However a substantive amount of information on seabirds was presented in evidence by Dr Taylor, Dr Bull, Mr Bartle and Dr Thompson. It was noted by the Expert Caucus Group that baseline seabirds data was required without clearly identifying why the data would be collected and how it would be used. Given that seabird deaths have already been documented by activities on the Rise (over many years), there was no mention as to why systematic data hasn t been collected to-date. I agree with Dr Bull and Dr Thompson that baseline data is not required. Risk to seabirds already exists from fishing activity on the Chatham Rise and impacts have been documented and described by Dr Thompson in evidence. Lighting of vessels does affect seabird behaviour. This is accepted and a comprehensive effort has been made to manage lighting on the vessel and to utilise a vessel lighting management plan. A Specific Management Plan and lighting mitigation have not been undertaken in New Zealand waters on any vessel as far as I am aware. Consent conditions include adaptive management should vessel strike occur for both rare and common seabird species. November 17,

9 Effects on marine mammals The Marine Mammals Expert Caucus Group concluded that ship strike and entanglement are sufficiently unlikely so as not to represent a significant concern. The caucus group noted the lack of baseline data hampers effective assessment of probable impacts on the marine mammal population. However Based on evidence and current data sufficient information on species present, their abundance and their probable use of the Chatham Rise is available. The available data indicates that the key areas utilised by marine mammals of the Chatham Rise are the flanks where larger mammals feed in deeper water. Within this environment mammals will have been interacting with fishing vessels and fishing activity which already occurs within key feeding areas. Overall, risks from direct interaction with marine mammals by the mining operation is considered to be very low. The expert caucus group discussed observers and passive acoustic monitoring. There wasn t agreement within the group as the overall value this would produce. PAM has limited effectiveness and is very expensive relative to its value and is unlikely to be effective given the continuous background noise of the mining vessel. The expert group recommended underwater sound monitoring of the mining operations. This has been included in the proposed consent conditions. November 17,

10 Ecosystem effects The Ecosystem Expert Caucus Group considered that the model used is fundamentally sound. Although the model was produced at the level of the Chatham Rise, Dr Pinkerton concluded that the anticipated direct impacts of mining on 10 of the 11 groups with the highest trophic importance are likely to be low or negligible. No direct effects on phytoplankton and any biota within euphotic zone. Across all of the trophic groups the groups with the with the with the highest direct/habitatmediated risk from mining were small demersal fish, macrozooplankton (krill), cephalopods, rattails and ghost sharks. For other groups the likely direct effects of mining/plume on productive capacity were considered to be low. The implications of these uncertainties are probably proportional to the area (or for some organisms the height above seabed) impacted relative to the greater Chatham Rise. November 17,

11 Corals and exclusion areas Cold water corals have been identified as the most significant community within the MLA. It has been recognised that G. dumosa thickets are a key feature of this part of the rise. G dumosa is predicted to occur in a number of areas within the EEZ and is known to occur at locations within the EEZ (refer Figure 50 AEE). Based on sample data (which reflects sample effort) the Chatham Rise is a focal point for this cold water coral. CRP undertook a significant spatial planning exercise to determine what areas should be set aside as non-mining areas. The exercise used best available information and tools to identify areas that provided maximum environmental and economic benefits. A significant area of seabed has been identified as mining exclusion areas. The areas identified include areas of G. dumosa. The results of the spatial planning were always seen as being a work in progress. Following discussion by the Benthic Ecology Expert Caucus Group, further validation is proposed. That will be followed by a revision of the exclusion areas. This intention has been included in the proposed consent conditions. November 17,

12 Radioactivity The Radioactivity Expert Caucus Group concluded that in seawater the toxicity of uranium is likely to be low. The Expert Caucus Group indicated concerns if the dilution was less than 200 times. Additional dilution modelling information provided to the EPA showed that initial dilution was about 750 times. The Expert Caucus Group also concluded that in the far field where dilution was significant (e.g., 5,000 times), that radioactivity in the water column required no further consideration. Measurement of radioactivity will be undertaken on pre- and post mining sediments. Measurement of Polonium 210 has been included in the proposed monitoring of trace elements in fish muscle (refer draft monitoring section of EMMP). Uranium (the element) will be monitored routinely in the discharge from the vessel (refer draft monitoring section of EMMP). November 17,

13 Recolonisation and colonisation trials Dr Rowden described recolonisation processes. The most significant process will be the colonisation of the post-mining sediment within the mined blocks. There has been discussion on the time recolonisation might take. Comments have been made about the potential slow growth of cold water coral species. Some recolonisation processes will start immediately in mined blocks. The ensuing biological community development will depend on the available colonists. It is certain that the biology in the mining blocks will be primarily a soft sediment benthos and it will take a number of years for that community to mature. The changes in the community structure will be determined by the ongoing physical changes that occur in the sediment. Colonisation trials will be conducted first in existing soft sediment habitat adjacent to available cold water corals to aid colonisation in the trial. This would be followed with work in mined areas once the results on trials are known. Concerns about soupy sediment not being suitable for colonisation are unlikely to be a concern, based on the settling trials reported by Ms Lescinski. November 17,

14 Monitoring A monitoring programme has been included in proposed consent conditions (Schedule 2), with further detail included in the draft, updated monitoring plan section of the EMMP. The key elements of the monitoring programme are: Ongoing assessment of sediment chemistry. Obtaining long term oceanographic data (currents etc.) at a mining and reference sites. Determining operational noise. Assessing depth of chalk layer in each mining block. Monitoring discharge water quality. Obtaining baseline water quality data. Obtaining long term turbidity data at mining sites and a reference site. Monitoring plume turbidity to confirm modelling predictions. November 17,

15 Monitoring (cont) Monitoring benthic ecology around mined blocks and at reference site. Monitoring key commercial fish quality. Monitoring recolonisation within mined blocks. Monitoring colonisation on substrate trials. Monitoring key commercial fish quality. Monitoring bird strike and landings on the mining vessel. Recording marine mammals observations. Recording the nature of coarse material caught by the 80 mm screen in the nodule separation system. November 17,