Figure 9. Time history of maximum water column TSS concentrations with bucket release rate of 2 percent at the Fox Point Reach Central (FPRC) site

ERDC TN-DOER-E12

July 2000

Figure 9. Time history of maximum water column TSS concentrations with bucket release rate of 2 per-

cent at the Fox Point Reach Central (FPRC) site. Also shown are TSS concentrations of 150 m

(500 ft) and 300 m (1,000 ft) up and down chane of the site

Figure 10 shows the time history of water column maximum TSS concentrations as a result of

dredging at the FPRC site with a bucket release rate of 4 percent. Again, the highest concentrations

(peaking at 150 mg/L) occur at the dredging site, with the next highest concentrations being

59 mg/L at 150 m (500 ft) up channel. At 300 m (1,000 ft) up channel, 150 m (500 ft) down channel,

and 300 m (1,000 ft) down channel of the site, maximum concentrations range from 30 to 39 mg/L.

As can be seen from an inspection of Table 4, the maximum concentrations approximately scale to

the strength of the source, e.g., 54 mg/L at a 1.5 percent release rate, 72 mg/L at 2 percent and

150 mg/L at 4 percent.

Figure 11 shows plan views of maximum concentrations computed during the simulation at a depth

of 6-8 m (20-26 ft) and vertical section views through the main axis of the plume at the Bullock

Point Reach South (BPRS) site. As for the Fox Point Reach sites, the plume axis is seen to generally

follow the channel axis. Release rates of 1.5, 2, and 4 percent are shown in the lower, center and

upper panels, respectively. The maximum concentrations at the source are 20, 27, and 53 mg/L for

the 1.5-, 2-, and 4-percent release rates, respectively. The section view is defined by the dashed

line in the plan view. Summary concentration information for this simulation is also presented in

Table 4.

Figure 12 shows plan views of maximum concentrations located at a depth of 8-10 m (26-33 ft) and

vertical section views through the main axis of the plume at the Rumstick Neck Reach Central

(RNRC) site. As for the other two sites, release rates of 1.5 percent, 2 percent and 4 percent are

shown in the lower, center and upper panels, respectively. At this site, the plume axis is seen to be

approximately 25 clockwise from the channel axis due to the direction of the currents at the site

not being aligned with the channel axis. The maximum concentrations at the source are 22, 30, and

60 mg/L for the 1.5-, 2-, and 4-percent release rates, respectively.