COASTAL ENVIRONMENT AND A NUCLEAR POWER PLANT

Abstract

Regulatory requirements and social constraints make it necessary to evaluate the environmental effects of a project and to incorporate into the design features to minimize adverse environmental impacts. This paper presents a case history of efforts to meet these requirements for a coastal power plant in southern California, Southern California Edison Company and San Diego Gas & Electric Company are jointly now constructing two additional units to the existing San Onofre Nuclear Generating Station, Being added are Units 2 and 3, The site, about 84 acres (34 ha,), is located within Camp Pendleton, a United States Marine Corps Base, about halfway between San Diego and Los Angeles, Califoria, The site (See Figure 1) is situated on the edge of a narrow coastal plain that extends from the coastline to a range of low hills, two miles inland, that have a maximum elevation of 1,725 feet (525 m) above sea level. The plain terminates at the beach in a line of wave-straightened cliffs, extending 60 to 80 feet (18 to 24m) above a narrow sandy beach. Numerous ravines are cut into the cliffs as a result of erosion by storm runoff from the coastal plain, Oceanographic features at the San Onofre site include a sandy bottom which slopes gradually to a depth of 60 feet (18 m) at about 10,000 feet (3,000 m) offshore. Mean maximum summer surface water temperature is about 73°F (23°C). During the fall and winter the water column is usually thermally homogeneous with a minimum temperature of approximately 56°F (13°C). Ocean currents at the site are chiefly tidally induced, although large scale low velocity circulation patterns are generally present. Very near to the southern California coast, local currents are influenced primarily by a combination of wind, tide, and local topography. The total current is ordinarily the sum of components due to wind, tide, and perhaps large-scale ocean circulations. Speed of the total current measured at San Onofre typically ranges from 0.10 to 1,75 knots, but averages 0.2 knots. San Onofre, Units 2 and 3 are being constructed southeast of, and immediately adjacent to existing Unit 1. Both the existing and the units under construction generate electrical power by using pressurized water nuclear reactors. Unit 1 has a capacity of 450 MWe and began commercial operation in 1968, Units 2 and 3 will each have a rated electrical output of 1,100 MWe. Commercial operation of Unit 2 is scheduled to begin in October 1981, and Unit 3 in January of 1983,