ABSTRACT

Standard Oil Company of California completed a seven point spread mooring facility in early 1973 for tankers in the 130,000 DWT class for the El Segundo Refinery in Los Angeles County, California. An environmental assessment of the proposed facilities was made. Mooring line tensions from winds, waves and currents were calculated. Concrete coated, steel pipelines of 36 and 14 inch diameters were pulled offshore 8300 ft. around a curve. Friction factors during pulling were measured.

I. INTRODUCTION

The increasing requirement for tanker supplied crude oil as regional production was declining required Standard Oil Company to add a marine terminal berth at its refinery at El Segundo in Los Angeles County, California. Prior to the construction, the marine terminal located on Santa Monica Bay included three offshore conventional, spread mooring berths, one principally for receiving crude oil and two for handling finished and semi-finished petroleum products. The increasing berth occupancy at the existing crude oil berth made it apparent that the refinery's crude oil needs could not be met unless additional crude oil tanker receiving facilities were built. Studies were commenced in the second half of 1971 to determine the optimum type of facilities for handling tankers in the range of 50,000 to 130,000 DWT which supply the terminal. The decision was made in early 1972 to install another CEM for receipt of crude oil with a submarine pipeline and onshore booster pump station and lines designed for an unloading rate up to 48,000 barrels per hour.

The mooring analysis of tankers in the 130,000 DWT class required the development of a computer program to evaluate the parameters with results checked by scale model tests. Studies to define all aspects of the project were completed and applications for a lease of State offshore land and for a U.S. Army Corps of Engineers permit were filed and granted.

The offshore pipe alignment to the new site required pulling through a reverse curvature as shown in Figure 1. This required special construction techniques to minimize lateral slippage and interference with an adjacent tanker berth. To maintain pipe stability during construction through the surf zone required an analysis of the hydrodynamic forces and the addition of temporary weight or one of the pipes. The first oil was received in the berth in March 1973.

II. ENVIRONMENTAL ASSESSMENT
A.INITIAL STUDIES

Prior to selecting the type of berthing facility for the terminal expansion, site surveys and oceanographic studies were conducted to supplement previous site data and operating experience. These studies, performed by Intersea Research Corporation with soils evaluation by Dames & Moore, confirmed the environmental suitability of a conventional buoy mooring berth to handle the tankers of the 100,000 to 130,000 DWT class safely on a routine basis. In addition, the studies provided information for locating the berth, for design of berth facilities and submarine pipelines, and for environmental impact assessment. The following summarizes these studies.

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