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Indicator species—A case for caution
ensuring that oil-based drilling muds and oil contaminated cuttings are taken ashore for disposal (Edwards, 1972). Any water produced with the oil, which is not reinjected, will be thoroughly treated to remove oil before discharge to the sea.
Spill Contingency Planning In conclusion, it is appropriate to consider the plans which have been made to deal with spills, should these occur in spite of the elaborate precautions which are being taken during drilling operations and safety features to be incorporated in the production platforms (Edwards, 1972). A joint UK Offshore Operators contingency plan has been drawn up by a Work Group representing the interests of the UK North Sea Operators and is under regular review. The basis of the plan is to deal with any spill at sea rather than run the risk of it contaminating the coastline. The plan provides for dispersal of oil using low toxicity oil dispersants (such as BP 1100X) which are stocked at Dundee and Aberdeen with back-up supplies at Great Yarmouth. Equipment is of the type developed by the Warren Spring Laboratory of the Department of Trade and Industry. It is recognized, however, that containment and recovery of spilt oil is preferable to dispersion and a recently developed open sea boom (the BP Sea-Pack) will shortly be added to equipment available. Past experience suggests that accidents due to offshore operations tend to result in smaller loss rates than tanker spills, but may continue for longer periods. A control operation thus stands a better chance of success. No offshore operation mishap has yet resulted in a spill comparable in size with that from the Torrey Canyon. Summarizing, BP believe, following a thorough examination of the environmental implications of the
Forties Field project, that the oil and gas resources can be utilized without damaging the marine environment or proving incompatible with other interests. The social, economic and political advantages of the development have been widely discussed elsewhere. T, E. LESTER L. R. BEYNON
BP Research Centre, Sunbury-on-Thames, UK. Battelle Northwest, Santa Barbara Channel Oil Pollution Incident, US Department of the Interior, FWPCA. Berry, W. L. (March 1972). J. Pet. Tech., 241. Brockis, G. J. (in the press). Sources of Sea Pollution by Oil. FAO. Chemical Engineering (May 19, 1969). 241. Duffy, McFadden (September-October, 1968). Louisiana Conservationist.
Edwards, J. H. (1972). J. Environmental Planning, 1: 12. Environmental Conservation Department (compiled by). United States and Regional Fishery Statistics, 1939-1969. Shell Oil Co., New York. Gaines, T. H. (1971). J. Water Poll. Control. Fed., 43: 651. Man's Impact on the Global Environment (1970). Report of the Study of Critical Environmental Properties. Cambridge, Massachusetts. National Oceanic and Atmospheric Administration (March 1972). National Marine Fisheries Services, CFS No 5900. Nelson, R. F. (March 1972). J. Pet. Tech., 225. Ocean Industry (January 1971). 7. Oil Pollution Incident, Platform Charlie, Main Pass Block 41, Field, Louisiana, WQ0 15080 FTV 05/71. Oversig. ht Hearings on OCS Lands Act. Held by Senate Committee on Interior and Insular Affairs, pursuant to S. Res. 45, March 23, 1972. Poricelli, J. D., Keith, J. F., & Storch, R. L. (1971). Tankers and the Ecology, Soc. Naval Arch. and Marine Engineers, New York. Sea Fisheries Statistical Tables (1971). Ministry of Agriculture, Fisheries and Food, London. St. Amant, L. S. (1972). J. Pet. Tech., 385. Straughan, D., et. al. (1971). Santa Barbara Oil Pollution and Marine Life, report of investigations into the spill, Allan Hancock Foundation, USC. World Oil (December 1970). 39.
Indicator Species--A Case for Caution The polychaete worm Capitella capitata has often been found in large numbers around sewage outfalls and is considered one of the best indicators of gross organic enrichment in coastal seas (Reish, 1970). During benthic surveys around the newly installed long sea ouffall in Liverpool Bay from the North Wirral, fairly large numbers were found in sandy sediments. They appeared in the first survey we made after the pipe was launched, at a density of about 880/m 2 where previously there were none. As they were only found in stations close to the out(all a natural reaction would have been to link the Capitella with enrichment from the out(all. However, in this case the Capitella appeared even before the pipe came into use and had gone 12 months later. Had there not been delays in completing the building work the additional surveys between pipe installation and commissioning would not have been made and erroneous inferences might have resulted. Although the discharge from the pipe cannot have been responsible for the change it is still likely that the out(all was its cause. After being hauled out to sea the 5 km long, 106 cm (OD) pipe (Roberts et al., 1972) was buried to at least 1 m by hydraulic jetting. Roughly 60-70 m s of sand, silt and, in places, the underlying boulder clay had to be displaced per 10 m run
of the pipeline. The sand would have quickly settled out leaving a vast amount of fines in suspension. As the work had to be carried out during calm weather, this silt would also have settled out nearby. The stations at which the Cap#ella were found were less than 250 m from the pipe and must have been blanketed by the silt deposition. Capitella apparently colonized this artificially produced habitat and subsequently the fines were winnowed out by the action of waves and tides. This left a healthy population which was living in association with animals typical of the clean sand nearby (median grain size: 0.22 mm). Populations of Capitella around new outfalls need to be viewed with caution as they may be due to a temporary disturbance of the environment by engineering work. This investigation is being sponsored by the Directorate General Water Engineering of the Department of the Environment.
R. A. EAGLE E. I. S. REES
Marine Science Laboratories, Menai Bridge, Anglesey, N. Wales. Reish, D. J. (1970). F.A.O. Tech. Conf. Doc. MP/70/R-9. Roberts, D. G. M., et al. (1972). Proc. Instn. civ. Engrs., suppl 5. 9.5
Spill Contingency Planning In conclusion, it is appropriate to consider the plans which have been made to deal with spills, should these occur in spite of the elaborate precautions which are being taken during drilling operations and safety features to be incorporated in the production platforms (Edwards, 1972). A joint UK Offshore Operators contingency plan has been drawn up by a Work Group representing the interests of the UK North Sea Operators and is under regular review. The basis of the plan is to deal with any spill at sea rather than run the risk of it contaminating the coastline. The plan provides for dispersal of oil using low toxicity oil dispersants (such as BP 1100X) which are stocked at Dundee and Aberdeen with back-up supplies at Great Yarmouth. Equipment is of the type developed by the Warren Spring Laboratory of the Department of Trade and Industry. It is recognized, however, that containment and recovery of spilt oil is preferable to dispersion and a recently developed open sea boom (the BP Sea-Pack) will shortly be added to equipment available. Past experience suggests that accidents due to offshore operations tend to result in smaller loss rates than tanker spills, but may continue for longer periods. A control operation thus stands a better chance of success. No offshore operation mishap has yet resulted in a spill comparable in size with that from the Torrey Canyon. Summarizing, BP believe, following a thorough examination of the environmental implications of the
Forties Field project, that the oil and gas resources can be utilized without damaging the marine environment or proving incompatible with other interests. The social, economic and political advantages of the development have been widely discussed elsewhere. T, E. LESTER L. R. BEYNON
BP Research Centre, Sunbury-on-Thames, UK. Battelle Northwest, Santa Barbara Channel Oil Pollution Incident, US Department of the Interior, FWPCA. Berry, W. L. (March 1972). J. Pet. Tech., 241. Brockis, G. J. (in the press). Sources of Sea Pollution by Oil. FAO. Chemical Engineering (May 19, 1969). 241. Duffy, McFadden (September-October, 1968). Louisiana Conservationist.
Edwards, J. H. (1972). J. Environmental Planning, 1: 12. Environmental Conservation Department (compiled by). United States and Regional Fishery Statistics, 1939-1969. Shell Oil Co., New York. Gaines, T. H. (1971). J. Water Poll. Control. Fed., 43: 651. Man's Impact on the Global Environment (1970). Report of the Study of Critical Environmental Properties. Cambridge, Massachusetts. National Oceanic and Atmospheric Administration (March 1972). National Marine Fisheries Services, CFS No 5900. Nelson, R. F. (March 1972). J. Pet. Tech., 225. Ocean Industry (January 1971). 7. Oil Pollution Incident, Platform Charlie, Main Pass Block 41, Field, Louisiana, WQ0 15080 FTV 05/71. Oversig. ht Hearings on OCS Lands Act. Held by Senate Committee on Interior and Insular Affairs, pursuant to S. Res. 45, March 23, 1972. Poricelli, J. D., Keith, J. F., & Storch, R. L. (1971). Tankers and the Ecology, Soc. Naval Arch. and Marine Engineers, New York. Sea Fisheries Statistical Tables (1971). Ministry of Agriculture, Fisheries and Food, London. St. Amant, L. S. (1972). J. Pet. Tech., 385. Straughan, D., et. al. (1971). Santa Barbara Oil Pollution and Marine Life, report of investigations into the spill, Allan Hancock Foundation, USC. World Oil (December 1970). 39.
Indicator Species--A Case for Caution The polychaete worm Capitella capitata has often been found in large numbers around sewage outfalls and is considered one of the best indicators of gross organic enrichment in coastal seas (Reish, 1970). During benthic surveys around the newly installed long sea ouffall in Liverpool Bay from the North Wirral, fairly large numbers were found in sandy sediments. They appeared in the first survey we made after the pipe was launched, at a density of about 880/m 2 where previously there were none. As they were only found in stations close to the out(all a natural reaction would have been to link the Capitella with enrichment from the out(all. However, in this case the Capitella appeared even before the pipe came into use and had gone 12 months later. Had there not been delays in completing the building work the additional surveys between pipe installation and commissioning would not have been made and erroneous inferences might have resulted. Although the discharge from the pipe cannot have been responsible for the change it is still likely that the out(all was its cause. After being hauled out to sea the 5 km long, 106 cm (OD) pipe (Roberts et al., 1972) was buried to at least 1 m by hydraulic jetting. Roughly 60-70 m s of sand, silt and, in places, the underlying boulder clay had to be displaced per 10 m run
of the pipeline. The sand would have quickly settled out leaving a vast amount of fines in suspension. As the work had to be carried out during calm weather, this silt would also have settled out nearby. The stations at which the Cap#ella were found were less than 250 m from the pipe and must have been blanketed by the silt deposition. Capitella apparently colonized this artificially produced habitat and subsequently the fines were winnowed out by the action of waves and tides. This left a healthy population which was living in association with animals typical of the clean sand nearby (median grain size: 0.22 mm). Populations of Capitella around new outfalls need to be viewed with caution as they may be due to a temporary disturbance of the environment by engineering work. This investigation is being sponsored by the Directorate General Water Engineering of the Department of the Environment.
R. A. EAGLE E. I. S. REES
Marine Science Laboratories, Menai Bridge, Anglesey, N. Wales. Reish, D. J. (1970). F.A.O. Tech. Conf. Doc. MP/70/R-9. Roberts, D. G. M., et al. (1972). Proc. Instn. civ. Engrs., suppl 5. 9.5