Pipeline crossing across Manori Creek, Bombay; advantages of marine acoustic techniques in route selection

Abstract

The National Institute of Oceanography (NIO) had carried out such survey in Bombay for obtaining geological informations in order to plan and design a pipeline route crossing Manori Creek to transport fresh water. The survey comprising of echosounding, side scan sonar and subbottom profiler followEd. by soil sampling and accompaniEd. by an accurate positioning system was carried out using a small boat. The survey revealed that the original proposed route, although was shortest, had to pass through rugged bed with a steep gradient and had practically no unconsolidated sediment cover, beside the same was passing through an existing ferry route and was in the midst of small fishing harbour. On the other hand, the seabed along the route suggested as per present survey, about 400-500 m north, was generally even and coverEd. by 2-3 m unconsolidated sediments and away from ferry route and fishing harbour. The thickness of the sediments prevailing in the large part of the route is sufficient to ensure necessary burial of pipelines to prevent damages by anchoring of the vessels or by some other way. The survey, therefore, has helped in identifying potential hazards and likely difficulties in laying and maintaining pipeline as also selecting proper alignment