with the construction of rubble-mound jetties in the 1930's. Also completed 
during the 1930's were the steel sheet-pile structures (dikes) located on the 
Gulf Intracoastal Waterway at Port Bolivar and Port O'Connor. 
6. Concrete capping was first used in the early 1900's at Sabine Pass, 
Galveston, and Freeport but in each case was limited to placement toward the 
landward end of a single jetty. During the 1930's and early 1940's additional 
concrete capping was used on both jetties at each of these projects. The 
Aransas Pass jetties were capped with concrete, and asphalt capping was placed 
on the Galveston jetties. These caps were rectangular or trapezoidal in cross 
section and were placed on top of the existing armor stone which itself was 
repaired or chinked with stone prior to capping. In the 1950's concrete was 
placed at the Brazos Island and Aransas Pass jetties. These sections varied 
from the previous caps in that the concrete was integrated directly into the 
cover stone layer, forming a homogenous section of concrete and armor stone. 
7. The period from 1962 to 1966 marks the era of maximum construction 
of new and existing breakwater and jetty structures. Constructed at this time 
were the breakwaters at Palacios and the jetties at Matagorda and Port Mans- 
field. Major portions of the jetties at Sabine Pass, Point Bolivar, Calves- 
ton, Port O'Connor, Aransas Pass, and Brazos Island were rehabilitated; and 
the Freeport jetties received minor repairs. Subsequent efforts include the 
construction of breakwaters at Port Aransas in 1973, the Colorado River 
jetties (which include a rubble-mound weir section) completed in 1986, and 
rehabilitation of the Brazos Island north jetty during the 1970's. 
8. Cross-section geometry and structure composition have been fairly 
consistent since at least 1962. Crown elevations vary between +4 and +8 ft 
mean low tide (mlt), and crown widths range from 8 to 20 ft. Side slopes are 
typically from 1V:1.5H to 1V:3H on trunk sections and 1V:2H to 1V:4H on head 
sections. Various sizes of granite stone are used in the section, beginning 
with a bedding layer of 0.5-in. to 200-lb stone and varying from 2 to 5 ft in 
thickness. This bedding layer has, in turn, acted as an apron by extending 
it, typically 5 to 50 ft beyond the cover layer toe. Recently, toe protection 
stone has been used in place of the extended bedding layer. Equal in size to 
the core stone, it buttresses both the bedding and cover layers. The core 
stone typically varies from 200 to 1,000 lb (but can be up to 4,000 1b on head 
sections) and, to decrease permeability, is supplemented with 0.5- to 4-in. 
filler stone. The geometry of the combined core and filler stone extends 
