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Determination of Acceptance Criteria for Cuttings Pile Management Executive Summary - Topic Area 9.1 Dames & Moore and TNO Institute of Environmental Sciences This report presents, for discussion, the first stage in the development of a framework methodology to determine 'acceptance criteria' for drill cuttings pile management. This work was carried out by Dames & Moore in conjunction with the Netherlands Organisation for Applied Scientific Research (TNO). The approach proposed in this report takes the form of a tiered risk-based assessment framework similar to the approach used for regulatory decision making on contaminated land issues in the UK, Europe and North America. The framework is designed to focus on the appropriate level of assessment for each site on a case by case basis by focusing resources on those sites which present most environmental risk whilst allowing sites identified as presenting little or no risk to exit the assessment process at an early stage. The proposed framework can be summarised as follows: TIER I  Preliminary Site Assessment This stage of the assessment would use readily available data and would facilitate the development of a conceptual site specific model outlining the following three key elements for the site: the source of contamination i.e. the likely contents of cuttings accumulations potential receptors for contaminants in or arising from cuttings accumulations in the surrounding environment pathways by which the potential receptors may become exposed to the contamination The proposed Tier I assessment takes the form of a series of 'questions and answers' and to enable rapid identification of sites that are highly unlikely to present an environmental risk, the Tier I assessment has been sub-divided into two sub-sections. Tier Ia is a simple and rapid desk-based questionnaire that would allow for the early identification and exit from the process of sites considered to present insignificant risk. Sites that fail Tier Ia would be subject to a more detailed assessment in Tier Ib where any potential environment hazard could be assessed using a scoring system, with 'higher' scores being assigned to drill cuttings accumulations presenting a greater risk to the environment. Sites that pass Tier Ib could exit the process once a full report on the assessment documenting the data used has been provided. A process of iteration at Tier I would be possible at sites where there is uncertainty, whereas all sites that fail Tier Ib should proceed to Tier II for further assessment. TIER II It is envisaged that the data requirements for the proposed Tier II assessment would necessitate an intrusive investigation of accumulated cuttings and surrounding sediments. The proposed Tier II assessment is sub-divided as follows: Tier IIa  Generic Quantitative Assessment The Tier IIa assessment involves comparison of chemical concentrations in accumulated drill cuttings and surrounding sediments with criteria for the protection of aquatic life or typical sediment background concentrations for the area. The comparison process would enable an assessment of the potential for chemical concentration in the cuttings accumulations (or surrounding sediments) to present a significant risk to the ecological receptors in the area. When the selecting criteria for application to any specific cuttings accumulation, the assessment objective and the basis on which the criteria were set would be considered. Tier IIb  Environmental Risk Assessment The objective of the Tier IIb assessment is to determine the hazards posed to environmental receptors following any potential disturbance to cutting accumulations that may give rise to the release of contaminants, including the chronic release of contaminants from accumulations left in situ. The assessment is designed to integrate hazards with the probability that an event will occur and identifies potential environmental impacts and risks by using an Environmental Hazard and Risk Assessment (EHRA) methodology. Sites that are found to have little or no environmental risk could exit the process at Tier II. These sites could broadly be defined as sites where one or more of the source, ecological receptor and exposure pathways may be identified but where the risk of these elements combining to an unacceptable environmental impact is deemed too insignificant. If moderate risk are identified the site can pass to Tier III or repeat the EHRA process by a process of iteration using new information until the risk is determined to be lower. All sites found to have a high or very high risk associated with the cutting accumulation would go forward to Tier III. TIER III  Comparative Assessment There are a number of options available for the management of drill cuttings accumulations, including the leave alone and monitor option. It should be noted that some of the remediation or removal options available may themselves have significant environmental effects associated with them and in some cases it may be necessary to select a combination of alternative options as the best option. In all cases a comparison of the options and evaluation of the short-term and long-term risks associated with each management option would be necessary. A framework for the comparative assessment process has not been developed at this stage as many of the other R&D activities for this JIP are considering some of the remediation options and management solutions. The results of some of these R&D activities may help inform this process in the next phase of work to be carried out in 2000. It should be noted that throughout this proposed tiered assessment framework, the precautionary principle is applied such that where information required for the assessment is unavailable or inadequate at any stage, a worst case is assumed until better information becomes available. The precautionary principle also assumes that at the start of each assessment, the site under investigation would 'fail' each stage of the assessment process and would pass through to Tier III. Only when the data are sufficient to demonstrate that there is minimal environmental risk from cuttings accumulation will the site under investigation be deemed to require no further action, thus leaving the process before Tier III. It is also essential that the assessment criteria and process are credible to both statutory, and, arguably, non-statutory consultees in order to ensure that there is broad-based understanding and support. To this end the process of assessment should be run in parallel with the stakeholder dialogue/consultation process in order to ensure the framework, associated appraisal and evaluation of options consider and, are informed by, external expectations.