(9) Summary of Test Results . Close examination of flow pattern 

 photos and velocity measurements showed conclusively that all of Reedy 

 Island Dike could be allowed to deteriorate without adverse effects on 

 hydraulic conditions or shoaling. The tests also showed that most of 

 Pea Patch Island Dike could likewise be allowed to deteriorate without 

 adverse effects; however, the results suggested that sufficient benefits 

 would accrue from maintaining the upstream 3,300 feet of the dike to de- 

 sign grade to justify the cost of rehabilitation and maintenance. Tests 

 of the Pennsville Dike showed conclusively that this structure should be 

 rehabilitated and maintained to the design conditions. These tests re- 

 sulted in a total savings of about $9,100,000 ($5 million for rehabili- 

 tation of Reedy Island Dike, and $4,100,000 for rehabilitation of the 

 unnecessary 15,700 feet of Pea Patch Island Dike), and showed that allow- 

 ing the Reedy Island Dike and part of Pea Patch Island Dike to deteriorate 

 would have no adverse effects on hydraulic or shoaling conditions in the 

 estuary. 



e. Disposal Islands — Matagorda Bay . 



CI) Project . Deepening existing navigation channel from 12 feet 

 to a 36-foot-deep new entrance, and location of dredged-material disposal. 



C2) Reference . Simmons and Rhodes (1966). 



(3) Laboratory . WES. 



(4) Test Period . December 1959 to September 1962. 



(5) Problem . Matagorda Bay is located on the Texas coast be- 

 tween Galveston and Corpus Christi, and until a 36-foot-deep navigation 

 channel to Point Comfort was authorized by Congress, navigation in the 

 bay was limited to a 12-foot-deep channel for barge tows and small craft. 

 The deep-draft project for Matagorda Bay is unique in that, instead of 

 the channel being gradually deepened a few feet at a time as has been 

 the case in most estuarine navigation projects, the channel was dredged 

 in one operation from -12 feet or less to a project depth of -36 feet. 

 Because of the large quantity of material to be dredged in the initial 

 excavation of the channel, and since the dredged material could not be 

 distributed widely in the bay because of potential redistribution of 



the material to the channel and possible adverse effects on marine life, 

 the question of proper selection of dredge-disposal areas was a highly 

 important one. 



(6) Purpose of Model Study . The model study was conducted for 

 the design of a deep-draft navigation channel. Studies were conducted 

 to determine the optimum locations for dredged-material disposal during 

 initial excavation and subsequent maintenance dredging of the channel. 



(7) The Model . The Matagorda Bay model was of the fixed-bed 

 type. It reproduced to linear scales of 1:1,000 horizontally and 1:100 

 vertically the prototype area shown in Figure 3-57. The model was about 

 200 feet long, 225 feet wide, and covered an area of about 30,000 square 



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