concrete curing mixture does not use water. Because these processes 

 may contaminate wastewaters with hydrocarbons and alkali and 

 other toxic substances, this water must be treated before release. 

 For example, provisions must be made for pipe cooling water and 

 whitewash to be collected in a sump or basin for treatment. Direct 

 runoff from the yard would carry pollutants to adjacent receiving 

 waters, particularly if the soil has poor permeability. Some pollu- 

 tants from waste disposal facilities may leach into the ecosystem. 



3.7 OIL REFINERIES 



3.7.1 Profile 



Refineries are large, highly visible industrial facilities which 

 handle highly flammable products, consume large amounts of water, require 

 large tracts of land, and may emit noise and odor pollution as well as 

 large amounts of air pollutants. Because of these and other problems, an 

 oil refinery may be the subject of more public controversy than any other 

 facility involved in OCS oil and gas development. Refineries are one of 

 the three major components of the petroleum products industry along with 

 petrochemical plants and gas processing plants (Section 3.8 and 3.9). 



The modern refinery is a complex network of highly automated 

 processing units connected by pipelines, storage tanks, and pumping 

 stations. Refinery components also include: wastewater treatment 

 facilities; ancillary buildings such as administration offices, machine 

 shops, fire stations, and warehouses; and truck and rail terminals. A 

 new refinery may require 3 or more years to build , employing a 

 work force of up to 3,000 during construction. The work force would 

 be reduced to about 550 permanent employees for a 200,000-barrel-per-day 

 (B/D) refinery operating 24 hours per day [7]. 



A refinery is designed as a series of processing units that separate, 

 convert, treat, or blend crude oil to make such products as gasoline, 

 fuel oil, butane, and coke (Figure 5). Crude oil is brought to a refinery 

 by pipeline or tanker or both and is temporarily stored in tanks. When 

 the crude enters the production stream, it may undergo as many as four 

 distinct processes: (1) separation into light, intermediate, or heavy 

 hydrocarbon groups; (2) conversion to more refined groups by processes 

 which chemically alter the molecules, including polymerization, 

 catalytic reforming, and cracking; (3) treatment, which removes the 

 odorous contaminants such as hydrogen sulfide; and (4) blending of base 

 stocks to produce a wider variety of products. After processing, the 

 products are temporarily stored for later distribution by pipeline, ship, 

 barge, or truck. 



If the crude oil supply to the refinery is "sour"--containing greater 

 than 0.5 percent sulphur compounds by weight--a special crude treatment, 

 or "sweetening", may be necessary before it enters the refinery stream. 



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