Page Reviewer Comment 



103 Pat Hughes [Suggests expansion of statement on the 500-m 



setback] No drilling should occur within the 

 heads of submarine canyons nor within 500 m of 

 the boundary of a canyon. .. .This statement 

 should include a list of the special features of 

 the canyons that have led this group to 

 recommend that drilling be prohibited within 

 500 m: 



1. Canyons are complex environments, 



2. Species diversity and abundance are 

 greater in canyons than on the adjacent 

 slope, 



3. Canyons do trap sediments from the 

 adjacent shelf, and 



4. Active resuspension of sediments in 

 canyons results in a higher potential for 

 the adsorption and removal of sediment- 

 reactive pollutants. 



103 Brad Butman [Questions the recommended 500-m setback for 



rigs, and suggests] .. .a larger distance to meet 

 the objectives listed. Especially around 

 Lydonia Canyon, the depositional region extends 

 several km onto the shelf around the rim. 



103 Robert Ayers [Suggests expansion of the statement regarding 



dilution of metals in the water column. 

 Additions or modifications are underlined.] 

 ...dilution and settling of metals ( they are 

 essentially 100 percent in particulate form or 

 adsorbed on particulates ) indicates that they 

 are not a biological problem. [Suggests 

 deletion of the phrase] .. ."although some 

 increases might be measurable." [Adds] They are 

 also unlikely to be a significant problem in the 

 canyon sediments. 



103 Brad Butman [While it is true that because of] dilution, 



metals are unlikely to be a problem, the report 

 should explicitly state that exploratory 

 drilling would probably not present a problem. 

 The simple calculations assume one well is 

 drilled, potentially increasing the chromium 

 concentration 20 ppm in a region where the 

 background is about 50 ppm. Thus, while one 



A-3 



