Structure-removal operations on the Outer Continental Shelf of the Gulf of Mexico— Programmatic environmental assessment
Abstract
This document discusses in some detail various aspects of oil and gas offshore platform Removal in the Gulf of Mexico. From The Finding of No Significant Impact: “The programmatic environmental assessment (EA) to evaluate the potential environmental impacts of structure-removal activities on the Gulf of Mexico (GOM) Outer Continental Shelf (OCS) has been completed. The evaluation encompasses all structure-removal operations (i.e., platform removals and well, pipeline, and mooring severances) under the regulatory authority of the Minerals Management Service (MMS). The EA has resulted in a Finding of No Significant Impact (FONSI). Based on this EA, we have concluded that the structure-removal activities evaluated in the EA will not significantly affect the quality of the human environment. Preparation of an environmental impact statement is not required.
The activities analyzed in the EA include vessel and equipment mobilization, structure preparation, nonexplosive- and explosive-severance activities, post-severance lifting and salvage, and site-clearance verification. The impact-producing factors of structure removals considered in the EA include seafloor disturbances, air emissions and water discharges, pressure and acoustic energy from explosive detonations, and space-use conflicts with other OCS users. Based on established significance criteria, the results of the impact analyses are that structure-removal activities are not expected to result in significant adverse impacts to any of the potentially affected resources. Potentially adverse but not significant impacts were identified for marine mammals and negligible to potentially adverse but not significant impacts were identified for sea turtles. In addition, no potentially-significant impacts were identified for air and water quality; fish, benthic, and archaeological resources; or other OCS pipeline, navigation, and military uses.
The MMS currently requires operators engaged in activities on the OCS, including structure-removal activities, to comply with a number of lease stipulations, Notices to Lessees, and other mitigation measures designed to reduce or eliminate impacts to sensitive environmental resources from impactproducing factors such as vessel or aircraft traffic, anchoring, and trash and debris. These mitigation measures are required under the OCS Lands Act, the Endangered Species Act (ESA), and the Marine Mammal Protection Act (MMPA) to ensure environmental protection, consistent environmental policy, and safety. As part of the impact analyses completed in the Structure-Removal Operations EA, a wide range of newly-developed, feasible mitigation measures were evaluated (Alternative A) as well as status quo mitigation means (Alternative B). In addition, a potential restriction on all explosive-severance activities conducted during structure-removal operations (Alternative C) was analyzed as an alternative to further reduce the potential for impacts to sea turtles and marine mammals.
Under the proposed action (Alternative A), the mitigation measures outlined in Appendix F of this EA will be required for all structure-removal operations in all water depths in the Western and Central Planning Areas and the currently-available lease sale area of the Eastern Planning Area of the GOM. The mitigation includes measures to reduce or negate potential impact-producing factors related to (1) support vessel mobilization/demobilization, (2) progressive transport, (3) site-clearance trawling, and (4) explosive-severance activities.”