Energy exports from an Arctic wilderness
Exxon Neftegas / Sakhalin Island, Russia
Sakhalin Island, Russia’s largest island, lies north of Japan. Densely forested with spruce, fir, and larch, the island has only about half a million inhabitants.
Exxon Neftegas handles marine transport of various processing and other modules that are delivered to the area of Chayvo on the east coast of Sakhalin. This is a seasonal operation, from about mid-June to the first of September, using a tug/barge combination that arrives offshore and is then maneuvered through a dredged access channel to a manmade temporary offloading facility inside the surf zone at Chayvo.
Exxon Neftegas retained Mott MacDonald to conduct a wave attenuation study aimed at determining the number and frequency of safe operating criteria to execute the marine delivery of cargo. We performed coastal engineering analysis and feasibility-level design, and provided cost estimates for wave protection alternatives.
Our analysis included two-dimensional wave transformation modeling for an alternatives analysis including a barge breakwater, a rubble-mound breakwater, a geobag breakwater, and an emergent sand dike with lee-side dredging. The solution included a phased approach, with the excavation of a barge delivery basin and the construction of an earthen berm to protect that excavation until the approach channel could be dredged.
As part of Exxon Neftegas’s temporary offloading facility dredging and self-lift operation, Mott MacDonald also provided navigation channel design, sedimentation analysis, and construction oversight, and determined the disposal of dredged material.
To operate the sea-lift module, the temporary offloading facility’s basin needed to be dredged and maintained with a barge mooring/offloading pad for the duration of the module delivery. Along with material removed for a barge access channel, all of the dredged material was placed on the adjacent shoreline to provide temporary wave protection. This reduced dredging during the maintenance phase of the sea-lift operation.
Mott MacDonald’s services helped our client to develop and effectively operate the entrance channel to and basin of the temporary offloading facility to successfully deliver vital components of their facility expansion.