Should be dropped as an item to consider

plants. To determine scale values, his technique uses a reference cooling system, and each alternative system is compared with it. He assigned the following scale values to the alternatives based on the reference alternative: very superior (+8), superior (+4), moderately superior (+2), marginally superior (+1), no difference (0), marginally inferior (—1), moderately inferior (—2), inferior (—4), and very inferior (—8).

Odum et al. (1971) discuss a scaling technique in which the actual measures of the decision factor for each alternative plan are normalized and expressed as a decimal of the largest measure for that factor. This technique represents linear scaling based on the maximum change.

A letter scaling system is described by Voorhees and Associates (1975). This method incorporates eighty environmental factors oriented to the types of projects conducted by the U.S. Department of Housing and Urban Development. The scaling system assigns a letter grade from A+ to C— for the impacts, with A+ representing a major beneficial impact and C— an undesirable detrimental change.

Duke et al. (1977) describe a scaling checklist for the environmental quality (EQ) account for water resource projects. Scaling follows establishing an evaluation guideline for each environmental factor. An evaluation guideline is defined as the smallest change in the highest existing quality in the region that is considered significant. For example, assuming that the highest existing quality for dissolved oxygen in a region is 8 mg/l, if a reduction of 1.5 mg/l is considered as significant, then the evaluation guideline is 1.5 mg/l, irrespective of the existing quality in a

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