Volume 34/Number 4/April 1997 cases preventing major pollution incidents. The International Salvage Union's Pollution Prevention Survey shows that these operations resulted in the recovery of nearly 2 million t of oils, chemicals and bunkers much of which could have polluted the oceans and shorelines without the intervention of salvors. The casualty total of 169 is higher than the corresponding figures for 1995 (141) and 1994 (126). However, the amount of cargo and bunkers involved fell slightly last year, from 2.1 million t in 1995 to 1.87 million t in 1996. The 1996 recovery of potential polluters included 1.75 million t of crude oil, nearly 62 000 t of chemicals and more than 58 000 t of bunkers. The grounding of the tanker Braer in the Shetlands in 1993 resulted in the loss of 85 000 t of crude oil. The salvors' recovery of crude oil last year equalled just over 20 spills of Braer size. A total of 20 ship-to-ship transfer operations were performed in 1996, as against 21 in 1995. The largest ship-to-ship operations last year involved the tankers Galp Funchal and Kraka. Both cases occurred in South African waters. Nearly 290 000 t of crude oil was transferred from the Galp Funchal, but this was exceeded when 343 400 t of crude oil cargo was transferred from the Kraka. T h e International Salvage Union carried out the first Pollution Prevention Survey in 1994. In the three years 1994-96 their salvors have assisted 436 ship casualties and recovered oil, chemicals and bunkers totalling 5.3 million t. The three-year total of pollutants recovered (5 345 218 t) consists of 4 974 341 t of crude oil, 205 317 t of hazardous chemicals and 165 560 t of crude oil. During this period 65 ship-to-ship operations were performed.
raise this to 1.5 million t for the next ten years. Gwilym Jones, the Welsh planning minister, has stated that proper monitoring procedures will be carried out including beach, nearshore and cliff-face profiling and annual photography and bathymetric surveys. If any of these show evidence of actual or potential damage the dredging will be stopped. The current decision was made after a hydraulic and sedimentary study by HR Wallingford. Another company is also wanting to remove 200 000 t of sand for the next ten years off Swansea and its looks likely that the proposal will be looked on favourably. Meanwhile building works on the Cardiff Bay Barrage are being held up by the unexpected presence of extra sand and silt in the tidal bay. The barrage is to be 1.1 km long and will seal off the Taft and Ely rivers creating a very large new freshwater lake. Dredging International have removed 1.8 million m 3 of silt to make way for the new barrage but have found there to be far more material present than expected. They are alleging that this build up has been caused by destabilizing of the River Taft when its new 70 m crossing was completed in 1995. They claim that slurries of sand and mud were carried downstream during the works and that this has built up in Cardiff Bay. A special trench had to be built to remove material before the barrage work could be started but the unexpected build up of extra material could delay the completion of the project. PHILIPPA AMBROSE
To Dredge Or Not To Dredge
Flooding in coastal areas of south-west England and Wales has intensified concern on UK capital cutbacks on flood defence work. According to a recent report in Surveyor, the UK Environment Agency (EA) and council officials denied that funding delays were a factor in the flooding experienced in the towns of Bideford, north Devon and Cardigan, mid-Wales. The EA's capital programme has been halved in recent years and will fall to £3 million in 1998 following cutbacks in support from the Ministry of Agriculture, Food and Fisheries and Devon and Cornwall county councils. Some twenty schemes due to start in 1998 will be delayed because of the cutbacks. High tides in the Torridge Estuary surged over the quayside in Bideford causing considerable damage to homes and traders' premises in the town. Local people blamed the flooding on delays on a planned defence scheme. However, the Bideford project is scheduled to go ahead next year, but will not finish until 2001, a year later than originally planned.
Two dredging sites are causing problems in Wales, UK. In one site the quantity of dredged material being removed from the sea is being questioned and in another a large project is being stalled by the presence of unexpected levels of sand and silt. Controversy is being fuelled by the agreement from the Welsh Office to allow increased levels of dredging from Nash Bank off Porthcawl in the Bristol Channel. Three aggregate companies look likely to find agreement to their plans to take millions more tonnes of dredged material out of the water. Friends of the Earth have expressed concern over the lack of research into the effect which the dredging may have on the local ecosystem and are pushing for the application of the precautionary principle until the research has been carried out. Currently the three companies, ARC Marine, United Marine Dredging and British Dredging Aggregates have licences to remove 300 000 t of dredge material for the next four years. The new proposals will
Concern Over Coastal Defence Cutbacks
Marine Pollution Bulletin
In Cardigan, angry residents said that funding cuts were partly to blame for slow progress on a flood alleviation scheme, proposed after heavy floods in the early 1990s. However, the local council say that these works would not have prevented the most recent ingress of water since it was caused by the unprecedented flooding of the River Teifi, which was not included in the proposal.
Waal Pollution Threat Averted It was a case of a stitch in time when a pollution threat to the Waal Estuary in the Netherlands was averted by the removal of the wrecks of two landing craft in a small harbour near Dodewaard. Five former Polish landing craft have been moored in the harbour for some years. Two had flooded at their moorings and had settled on the bottom. The wrecks contained 130 m 3 of bunker oil which could have caused environmental damage had it been released. However a wreck removal and bunker recovery plan had been prepared following a diving survey in November last year. This was therefore put straight into action and under a contract from Rijkswaterstaat--the Dutch Government agency--a salvage company, Takmarine, recovered the two wrecks, each weighing in at 500 t. They used two floating sheerleg cranes each rated at 400 t. Work on this wreck removal contract was due to commence in early January, but this was postponed due to the severe winter weather which rendered the harbour icebound. However the conditions improved at the end of January and the two cranes together with the salvage vessel Jacomina and support tugs, were mobilized for the operation. The landing craft were lifted in turn and delivered to a Haarlem scrapyard.
Future TBT Phase-Out Likely The IMO are currently considering phasing out, and eventually banning, anti-fouling paints containing tributyltin (TBT). Restrictions on the use of TBT antifoulers have been in place in Britain since 1987 when it emerged that the compounds caused deformities in oysters and changed the sex of whelks. Most other European countries followed suit, banning TBT paints on yachts and pleasure boats. The IMO may now extend this ban to commercial shipping to progressively reduce the impact of TBT on the marine environment. A submission by the North Sea states was made to last year's meeting of the IMO's Marine Environment Protection Committee (MEPC), calling for a group to be set up to work on reducing the harmful effects from anti-fouling paints. A correspondence group of twentyfive experts was duly convened in response to this call, 224
which is due to present its preliminary findings at the next MEPC meeting. In the past, the IMO have resisted extending the TBT restrictions, owing to a lack of suitable alternative antifouling systems. In their submission, the North Sea states point out that there is little pressure to develop alternatives in the absence of a ban. Their ultimate aim is to phase out the use of TBTs on all ships world wide, but suggest a total ban must be a long-term goal, as sufficient time must be allowed for the development of alternatives. In the short-term, the North Sea states' submission proposes a series of measures including limitations on vessel size, dry-docking frequency and geographical restrictions to progressively reduce the impact of TBT. Recent research has shown that TBT can remain in sediments for up to fifty years. Fish can accumulate TBT in their tissues by ingesting worms and larvae living in the sediment. SHIRLEY HENDERSON
Singapore Invests in its Wastewater Treatment A huge project has been put in motion to redesign the effluent wastewater systems of Singapore. Two US companies have won the contracts and will work together on a joint venture to design and manage a deep tunnel wastewater collection, treatment and disposal system. The first phase is estimated to cost in the region of $3-4.7 billion when completed in 2005. The government itself will pay for the improvements adding to their $1.4 billion already spent in the last 20 years. In its current round of spending it is also investing $1.3 billion in two new solid waste disposal plants, a landfill to reclaim spoil sites and one of the largest incinerators in the world. Details of the wastewater proposals are now available. Singapore has little spare land and the plans have had to take this into account. To provide funds 290 ha of land surrounding six wastewater treatment centres will be sold and developed. These two plants will be replaced by two vast underground plants. CH2M Hill Cos. from Denver has won the contract to construct the wastewater treatment plants. According to the recent plans put forward by the developing company, the underground plants will be covered by football pitches for local use. The plants will deal with the treatment of at least 4 million m 3 of wastewater per day and will release it through outfalls extending into the Singapore and Johore Straits. An underground tunnel network is also to be provided. The contract has been won by Parsons Brinckerhoff Inc. from New York, US. Their remit is to build 80 km of tunnels linking across the island. The tunnels are to be as much as 90 m deep and 6.5 m in