IV-397 



types of extractive activities exist in the estuarine zone: 

 (1) sub-bottom mining of sulfur and petroleum, (2) mining of 

 materials such as sand, gravel, and oyster shell from the estu- 

 arine bottom, and (3) mineral extraction directly from the water. 

 Each creates a different water-quality problem. 



The sub-bottom operations, especially for petroleum, interfere 

 with the aquatic habitat in several ways. In the exploration 

 phase, the use of seismic explosions can be detrimental to the 

 biota in the immediate vicinity. Drilling activities always 

 present the potential threat of a blowout or rupture resulting in 

 a wild well (Figure IV. 5. 17). Potential problems in the production 

 phase include the possibility of collision or storm damage to the 

 rig and the disposal of the oil well brine. Transportation of 

 oil whether by ship or pipeline poses an additional pollution 

 threat. 



In sulphur mining, the Frasch process is generally used; super- 

 heated water (325°F.) is pumped into the sulfur formation and 

 molten sulfur is pumped out. The bleedoff waters must be vented 

 from the deposit, and these waters are highly saline with a rather 

 high hydrogen sulfide content (Figure IV. 5. 18). 



Both petroleum and sulfur mining cause a secondary impact due to 

 the shoreline support facilities that accompany their development. 



