Michel, J; Gilbert, T; Etkin, DS; Urban, R; Waldron, J; Blocksidge, CT
There has been increased awareness and concern about the oil-pollution risks posed by sunken wrecks, both recent and relic. Recent cases such as M/T Prestige and M/T Erika, where the vessel or portions of the vessel sank with large volumes of heavy, persistent oils onboard, have triggered public demand for removal of the oil, regardless of the pollution threat. Mystery spills have been linked to older wrecks that have started leaking, such as USS Mississinewa and SS Jacob Luckenbach. Funding is usually a limitation, even when there is a responsible party, because of the high costs of oil and/or wreck removal. However, the concern is that these wrecks will eventually release their oil, either slowly or catastrophically resulting in significant damage to the environment. There are many complex issues associated with the proactive response to these potentially polluting wrecks: Which pose the greatest risks? Who should pay for assessment and removal costs? What are feasible and cost-effective technologies for assessment and oil removal? The goals of this paper are to provide an objective analysis of the current state of potentially polluting wrecks, due to the discharge of petroleum, or the substantial threat of such a discharge, and to offer considerations for addressing the issues. A step-wise process was followed. The first step was to compile existing data into the first-ever worldwide database of potentially polluting wrecks. The database includes non-tank vessels of at least 400 gross tonnage (GT) holding petroleum-based oil as fuel/bunkers (and for operations) and tank vessels of at least 150 GT holding petroleum-based oil as cargo and fuel/bunkers (and for operations). The intent was to consider those wrecks that posed a significant oil-pollution risk. The resulting database includes 8,569 potentially polluting wrecks, with 1,583 tank vessels and 6,986 non-tank vessels. Estimates of the likely volume of oil remaining onboard these wrecks were made, particularly when the volume of oil onboard was not known. A high estimate was calculated assuming that a tank vessel had at least 80 percent of its cargo capacity on board, and bunkers were assumed to be 70 percent full. A low estimate was calculated based on the assumption that half of the vessels would have been 80 percent full and half would have been 20 percent full at the time of sinking and that an estimated 80 percent of the oil would have either spilled at the time of the sinking or seeped out in the years following. The results were a low estimate of 2.5 million tonnes (757 million gallons) and a high estimate of 20.4 million tonnes (6 billion gallons). The next step was a review of the different regulatory and financial regimes both in the United States and internationally. The United States has fairly structured pollution response and wreck removal regimes under the Wreck Act and the Clean Water Act, as amended by the Oil Pollution Act of 1990 (OPA 90). The Wreck Act provides a mechanism to remove wrecked vessels from navigable channels. OPA 90 provides a source of funds should an owner of a wrecked vessel either not be found or be unwilling to remove or otherwise mitigate the discharge or threat of discharge from a wreck, including removal of the wreck when it is determined to be absolutely necessary to abate the discharge, or substantial threat of such a discharge, to the environment. The major issue with the United States revolves around whether a wreck must be removed in order to abate the discharge, or threat of discharge, of its oil polluting contents under OPA 90. Internationally, States have various pollution-related wreck removal authorities, but they are generally weak because of the lack of funding mechanisms. The international community has struggled with a policy regarding wreck removal and began officially considering a comprehensive Draft Wreck Removal Convention (DWRC) in 1998. One of the most controversial points of this convention is the funding mechanism. The DWRC's inclusion of a financial security regime is intended to ensure that th owners of sunken vessels are primarily liable and responsible for marking and removing the polluting wrecks. The current draft of the DWRC contemplates using a system of insurance and other financial security to ensure that mitigating action is taken, which may arguably take care of a great percentage of the international removal efforts. However, an international fund should be established to provide funding in case the owner cannot be found or such funds are insufficient. This has been a major issue in the development of the DWRC. Adoption of the DWRC, even in its present form, could greatly improve the current gap internationally with regard to mitigating polluting or potentially polluting wrecks. The establishment of universally acceptable international rules on the rights and obligations of States and shipowners in responding to wrecks with dangerous cargoes and posing a threat to navigation and/or the environment may be a welcome improvement to the current situation. The next step was to evaluate the technological feasibility for assessing the potential for an oil discharge from a vessel and oil offloading methods. Salvors and the response community have shown that they can be innovative and cost-conscious. There are few technological limitations to recovering oil from deep depths, cold waters, and other challenging conditions. As demonstrated by the recent and successful removal of most of the 14,000 tonnes of heavy oil remaining onboard the Prestige wreck in waters over 3,500 meters deep, remotely operated vehicles (ROVs) can be modified to perform a wide range of assessment and removal actions. Some of the remaining oil removal challenges are viscous oils that require heating to make them pumpable, double-hull oil cargo tanks that may increase the difficulty and risk of oil recovery operations, locating and estimating the volume of oil in cargo and other spaces, and close-out procedures. Further research is needed on wreck corrosion rates and field survey methods to support development of a wreck stability model. One of the key questions to be answered during a wreck assessment is "When might the wreck start to leak?" Better methods are needed to collect and interpret the data to assist in making this assessment. The last step was development of guidance for assessing the risks and consequences of oil releases from potentially polluting wrecks. It is clear that most of the oil remaining on these wrecks will eventually be released. More than 75 percent of the wrecks date back to World War II and thus have been underwater for 55-65 years, so there is added concern that corrosion will lead to increased oil discharges. It is also clear the consequence of such discharges, when they occur, will vary greatly. There are limited funds available to proactively remove the oil, thus it is important that oil removal efforts be prioritized according to the likelihood and consequence of oil releases. Therefore, there is a need for a systematic risk assessment of potentially polluting wrecks. Such a framework would include ranking categories related to site, environmental, and economic criteria. Furthermore, the available databases of known wrecks lack key data for use in fully characterizing risk to the environment. Standardization of information and methods of risk assessment for individual wrecks or groups of wrecks could provide enough state and regional impetus for enactment of a viable international legal regime concerning action on such wrecks.