Mock Mathis: I have been involved in the construction of most of the coastal structural 

 projects discussed here, including the Belle Pass jetties, the Grande Isle jetties, the 

 East Timbalier project and the Holly Beach project. 



I do not agree with some of the things said about East Timbalier Island. We 

 began working there in 1965 and it has been virtually an annual experiment financed 

 by Gulf Oil Company. Where were you experts when I needed you? There was a lack 

 of any one willing to make a commitment as to what would work. Gulf made a 

 commitment of between $15 million and $25 million. We have followed the advice of 

 world experts on this project. I do not agree that the riprap seawall has not 

 protected the island; there is a lot of island left. One of our errors was scraping 

 sand from the low dunes of +5 feet to +3 feet msl on the island. This caused some 

 washover channels. Much of the sand has gone to the back protection dike built to 

 an elevation of +6 feet and hard enough for trucks to run on. Another error is the 

 permeable nature of the rock structure, which has allowed tidal flow to erode behind 

 the rocks. Nonetheless, these experiences should now serve as valuable experiments. 



Charles Groat: Several speakers brought up the point of the relative sand starvation of 

 the Louisiana barriers. The Legislature's recommendations included geophysical 

 exploration of offshore sand sources which could be used for nourishment. 



Dag Nunrimedal: The Corps of Engineer's Coastal Engineering Research Center has had a 

 successful project to identify sand sources along the east coast. Some sources do 

 exist off the Louisiana coast which could be used. However, if we remove too much 

 sand from these ar^as disequilibrium will result and the sand may be transported 

 back into these holes. 



Murray Hebert: I agree with Mr. Mathis that if it were not for the rocks protecting East 

 Timbalier Island we would have much less of that island remaining. 



Jay Combe: I disagree that seawall structures such as the Galveston Seawall cause 

 erosion. If there were no erosion in the first place, there would have been no need 

 for the seawall. Without the seawall the shoreline would have eroded farther into 

 the sand dunes. 



Dag Nummedal: That is not true. Most seawalls are erected to protect the land. Any 

 natural shoreline, even if it recedes, maintains a beach. 



Robert Morton: The Galveston seawall was built in response to the loss of lives. It has 

 been documented that locally the increased shoreline erosion is attributed to the 

 seawall. 



With regard to offshore sand sources, we have surveyed the Texas inner shelf 

 using high resolution seismic methods. In an area off Galveston our seismic survey 

 indicated a lack of viable sand supplies. The Corps of Engineers subsequently looked 

 more intensely only to find a thin veneer of relict sand over Pleistocence mud; an 

 insufficient source of sand for beach nourishment. Offshore sand supplies must be 

 both extensive enough and located near the site of beach nourishment. 



Irving Mendelssohn: Sand nourishment should be followed by vegetative stabilization 

 because, in the past, unstabilized sand has often been washed away. 



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