discharge location would now be approximately 800 m short of the western extent of the ebb 

 shoal. This difference may well be attributed to an alongshore growth of the ebb shoal in the 

 years between the two studies. This emphasizes the need for flexibility in bypassing. 



PRC Engineering prepared a comparison table that graded each alternative on eight criteria 

 (engineering, reliability, risk of damage, maintenance, operation, environmental, social, and 

 aesthetic). Each of these criteria were weighted with engineering effectiveness (meeting 

 operating schedules, productivity during rough seas, etc.) having the most weight, reliability, risk 

 of damage, maintenance, and operation all having the next highest weight, environmental having 

 the next highest weight, and social and aesthetic having the lowest weight. PRC Engineering's 

 final recommendation showed that the floating dredge operating in the channel had the highest 

 weighted score with the fixed dredge pump/jetpump alternatives being the next highest. When 

 considering costs and bypassing rate, PRC Engineering recommended that for transport rates less 

 than 46,000 mVyear (60,000 ydVyear), the hydraulic dredge was the best choice. For transport 

 rates greater than 77,000 m 3 /year (100,000 ydVyear), the fixed jetpump system without crane was 

 the best choice. PRC Engineering further recommended that for rates between 46,000 mVyear 

 (60,000 ydVyear) and 77,000 mVyear (100,000 ydVyear), both methods should be more closely 

 examined. 



80 Chapter 6 Other Bypassing Studies 



