Produced water was slightly toxic to marine organisms with 

 crustaceans more sensitive than fish (Zein-Eldin and Keney 1979; ERCO 

 1980) as indicated in the following table. 



Concentration (ppm) Concentration 



Organism x 96-h LC50 x 48-h LC50 (_£) 



Brown Shrimp 



Larvae - 9,500 1.0 



Subadult 100,000 - 10.0 



Adult 116.000 - 11,0 



White Shrimp 



Subadult 68,000 - 6.8 



Adult 70,000 - 7.0 



Barnacle 83,000 - 8.3 



Crested Blenny 269,000 - 26.9 



The most sensitive organism among those tested was the larval brown 

 shrimp which had a mean 48-h LC50 of about 9,500 ppm (1$ produced water 

 in seawater) . 



Gallaway et al. (1980) used two methods to project the 

 concentrations of produced water in the receiving seawater. The first 

 method was utilized by Environmental Research and Technology, Inc. 

 (ERT) (1980) to establish an initial concentration for use in 

 hydrodynamic models. Based upon dye studies by Workman and Jones 

 (1979), the produced water (due to turbulent mixing beneath the 

 platform) was assumed to completely mix in a volume of water 

 approximately one-eighth of the volume occupied by the platform (Figure 

 23). The relative contaminant concentration (0.088$) projected by this 

 method agreed well with the pollutant concentrations observed in waters 

 beneath the platform (see Middleditch and West 1980; Tillery 1980) given 

 the initial levels of contaminants in the produced water being 

 discharged. 



The second method employed was an analytic steady state 

 approximation for diffusion from a continuous point source discharge 

 having a mean advective component (ambient current) perpendicular to the 

 dispersion. Eddy diffusion coefficients (Ky = 0.1 m 2 /s; Kz = 0.01 nrVs) 



60 



