combustible contaminants such as scale and sludge from cleaning boilers, 

 storage tank cleaning sludge, iron oxide, and wood chips used to sweeten 

 sour gas streams, and contaminated sulfur, require special collection and 

 disposal methods. 



Subproject: Industrial Wastewater Systems (SP-14) 



Disturbing Activity: Wastewater disposal 



Wastewaters from gas processing plants include process water, boiler 

 wastewater, and cooling water which accounts for 70 to 100 percent of the 

 total [7]. Wastewater contaminants include: chromium, zinc, and chlorine 

 for cooling waters; dissolved hydrocarbons, heavy metals, grease, and 

 other toxic compounds for process waters; and phosphates, sulfite, and 

 tannin for boiler wastewaters. Wastewater treatment programs must be 

 designed to meet the conditions of specific gas processing plants. 

 Domestic wastewater is not a significant factor in wastewater loads 

 because of the small number of employees. Wastewater treatment systems 

 should be designed to function efficiently under continuous operation, (a 

 malfunction can release large amounts of pollutants in a short time) and 

 suitable "backup" capacity should be available. 



Subproject: Industrial Cooling Water Systems ($P-15) 



Disturbing Activity: Circulation of cooling water 



Cooling system designs for gas processing plants may use air or water 

 heat exchange or a combination of the two. Where water is used, closed- 

 cycle systems are better than open cycle (once-through) designs. The 

 once-through systems generate maximum water demand, produce maximum volumes 

 of heated effluent, and cause the greatest disturbances to the aquatic 

 environment. Closed-cycle (recirculating) water cooling designs, which 

 employ cooling towers or ponds, generate far less effluent and reduce 

 water demand. However, chemicals such as hypochlorite that are added to 

 cooling water to reduce corrosion in cooling towers and condenser systems 

 are highly toxic and require collection and treatment. 



3.10 LIQUEFIED NATURAL GAS SYSTEMS 



3.10.1 Profile 



Liquefied natural gas (LNG) systems provide a convenient means for 

 transporting gas over distances too great for pipelines. They are expen- 

 sive to build and operate, and are only economically feasible where there 

 is high demand for gas and the source area has an abundant supply of gas. 

 The market situation in the United States in recent years has been one 

 of increasing demand for domestic gas and declining production. 



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