| Offshore drilling operations generate rock cuttings and spent drilling fluids wastes during the well drilling phase. The wastes contain toxic substances that are harmful to the marine ecosystem. Discharge limitations and restrictive guidelines in different jurisdictions of the world are under development. Pollution prevention by encouraging synthetic based fluids (SBFs) in place of traditional oil based fluids has been supported in recent years. Despite having environmentally benign characteristics, SBFs associated wastes still have a certain amount of pollutants due to barite and contamination with formation oil.; The main aim of this study was to develop a risk management framework for determining the best drilling waste discharge scenario for disposal in the marine environment.; Fate modeling in this research was performed using fugacity and aquivalence based concepts. A chemical specific approach was employed for contaminant fate modeling. A steady state non-equilibrium water and sediment interaction model with probabilistic inputs was used to determine the contaminant concentrations in the water column and pore water.; The predicted environmental concentration (PEC) values were converted into exposure concentrations (EC) by adjusting for bioavailability and probability of exposure. The whole ecological community was defined as assessment endpoints. The toxicity assessment analyses were based on the lognormally distributed predicted no effect concentrations ( PNEC). The composite ecological risk for drilling waste was determined by integrating the individual risk estimates assuming statistically independent events.; The human health risk methodology was based on the consumption of contaminated seafood. A probabilistic framework for human health risk assessment was developed for cancer and non-cancer risk estimates. The chronic daily intake rate ( CDI) was established based on fish ingestion rates, lipid content, bioconcentration factors, exposure duration, exposure frequency, and averaging time. The LHS based MC simulations were performed to estimate the CDI. Arsenic was the only proven human carcinogen in the drilling waste stream.; A risk management methodology using fuzzy composite programming (CP) was developed. The costs for treatment, drilling fluid loss due to discharge and ecological and human health damages were estimated.; The risk management framework was applied to a hypothetical case study on the East Coast of Canada. Five discharge scenarios, or management alternatives including 10.0%, 8.5%, 7.0%, 5.5% and 4.0% attached base fluids to wet cuttings, were selected for the analysis. (Abstract shortened by UMI.)... |
