Date(s) 
1984- 
1986 
Table 5 
Colorado River Jetties 
Mouth of the Colorado River, Texas 
Construction and Rehabilitation History 
As part of navigational improvements, two rubble-mound jetties were 
constructed at the mouth of the Colorado River (Figures 6 and 7) pro- 
viding protection for the 15- by 200-ft entrance channel. The south 
jetty is 1,450 ft long, and the north jetty, which contains a rubble- 
mound weir, is 2,650 ft long. The north jetty weir section begins 
410 ft from landward end, at about the mlt contour, and extends 
1,000 ft seaward to about the -8 ft mlt contour. The seaward ends of 
the north and south jetties are about 1,800 ft apart and situated in 
water depths of approximately -12 and -5 ft mlt, respectively. The 
jetty design incorporated an impoundment basin on the channel side of 
the north jetty to trap littoral drift material passing over the 
weir. The basin, initially dredged to a capacity of 740,000 cu yd, 
will be dredged periodically and the material deposited downdrift of 
the jetties. The crown elevations of the weir section and remaining 
jetty sections are 0 and +8 ft mlt, respectively. The design crown 
width and side slopes are 16 ft and 1V:3H, respectively. The typical 
jetty trunk section (Figure 7) consisted of a 2- to 3-ft-thick 
bedding layer of 0.5-in. to 200-lb stone, 200- to 1,000-1lb core stone 
(2,000-1b maximum on the seaward leg of the north jetty), and a 
single layer of rectangular granite cover stone. The 200-ft-long 
head sections (at the seaward ends) were similar to the trunk sec- 
tions except for a double layer of cover stone on the side slopes and 
a 5-ft-thick bedding layer on the north jetty. The cover stone 
varied in size from 4 to 6 tons at the landward ends to maximums of 
16 to 18 tons and 10 to 12 tons at the seaward ends of the north and 
south jetties, respectively. To buttress the armor layer at the 
slope toes, the outer two to three cover stones were to be placed 
horizontally on the bedding layer. Cover stone sizes were selected 
using design wave heights of up to 17.6 ft (north jetty head) and 
Hudson's slope stability formula. The permeability of the jetties 
was decreased by chinking a section of the core stone, extending the 
full width of the crown and downward on 1V:1H slide slopes, with 0.5- 
to 4-in. filler stone. The absence of a core stone section was the 
only difference between the weir and trunk sections. Toe protection 
stone was placed on all sections of the jetties, buttressing the 
bedding layer and outermost cover stone (thus the thickness varied 
from 5 to 9.5 ft). The width of the toe protection section was 5 ft 
except on the head sections where it was 10 ft, and the design outer 
side slope was 1V:1H. The stone size was the same as the adjacent 
core stone (weir section used 200- to 2,000-lb stone). Transition 
sections, 100 ft long, were provided for changes in grade (or stone 
geometry) among weir, trunk, and head sections. Approximately 
490,000 cu yd of material from the channel and deposition basin were 
to be used as fill on the west side of the channel and shoreline 
(Continued) 
26 
