 |
||
|
|
||
|
Page Title:
Step 5 - Check length-dependent assumptions. |
||
| |||||||||||||||
|
|
 -3
C e = 3.5 g/ L (3.5 10 mg/L)
-1
Cs = 0.25 g/L-1 ( 2.5 10-4 mg/L )
Cb < 0.1 g/L-1 (1.0 10-4 mg/L )
In order to be environmentally protective, it would be wise to assume that
the background concentration is only just under the detection limit, rather than
zero. Therefore use:
Cb = 1.0 10-4 mg/L
Calculate mixing-zone length:
2
1 Qe C e
L=
π u ( C - C )d
Et s b
1
L=
-1
-1
2
π(0.0441m / sec )(0.579 m/sec )
( 0.425m2 /sec ) (3.5 10-3 mg/L )
( 2.5 - 1.0) 10-4 mg/L ( 2.54m)
L = 190 m (623 ft)
Step 5 - Check length-dependent assumptions.
a. Step 5.1. Verify that the flow of the water body near the mixing zone
can be treated as a steady state flow.
u
L ≤ Tc
10
therefore:
10L
Tc ≥
u
10(190 m)
Tc ≥
0.579 m/ sec-1
T c ≥ 3,280 sec (55 min )
This is acceptable since the river flow will certainly not change by 10 per-
cent in less than 1 hr.
E13
Appendix E Evaluation of Mixing in Surface Waters
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us - Support Integrated Publishing |
