316(b) Impingement

Report
Fish Impingement and
Survival on “Fish Friendly”
Traveling Water Screens
Justin B. Mitchell
APC Compliance Studies
Alabama Water Resources Association Conference
Orange Beach, Alabama
September 07, 2012
Introduction
 Impingement-
The death of fish
and aquatic organisms that are
pinned on the cooling water intake
structure (CWIS).
Impingement
Proposed Impingement Rule

Section 316(b) of the Clean Water Act



1.
2.
3.
Withdraw >2 MGD from waters of the US
>25% used for cooling purposes
Primary Compliance Options:
Cooling Towers
Intake velocity <0.5 fps
Traveling Screen Modifications and Biological
Monitoring



Fish Buckets
Fish Return System
48 hr Mortality Limit Criteria:
Average annual mortality rate <12%
Monthly maximum mortality rate <31%
Gorgas Steam Plant






Walker County, AL
Black Warrior River (Mulberry
Fork)
1,200 MW
5 generating units
FGD (scrubber)
2 separate CWIS


Units 6-7
Units 8-10
Gorgas Approach
SSI Band Screen Retrofit





Cost effective, $1.3M
Operationally feasible
Moribund fish (i.e. fish health) exceptions
Entrapment
Can this technology achieve the mortality limits?
Modified Band Screen with Fish
Buckets
Low and High Pressure Spray
Fish Trough
Debris Trough
Intake Flow
Fish Return and Aquaria System
Study Objectives
1.
Characterize Fish Impingement Rates
Debris trough
 Fish trough

2.
3.
4.
Evaluate Screen Operational Efficiency
Investigate 48 hr Latent Impingement Mortality
Examine Rates of Sick or Moribund Fish
Impingement Samples
Collected to Date


Fish Return Trough
Debris Trough
3 8-hr sample/day

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Day
Evening
Night
4 days/week (Jan-Feb)
2 days/biweek (Mar-Jun)
Total Samples = 72 8-hr samples/trough
Species Diversity


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5,300 fish
30 species
11 families
Recreationally
Important spp.
Fragile spp.
Common Species
Shad & Non-shad Composition
80%
0.9%
8%
11%
Fish Separation
92.5%
87.6%
12.4%
7.4%
Survivability Experimental
Design



Biweekly Impingement
Fish Return Trough only
Fish Collection
2 days/week
48 Hourly Latent
Impingement Mortality
(LIM) Observations
Shift
0600-1400
1400-2200
2200-0600
Monday
Tuesday
Fish Collection &
LIM Observations
Fish Collection &
LIM Observations
Fish Collection &
LIM Observations
Fish Collection &
LIM Observations
Fish Collection &
LIM Observations
Fish Collection &
LIM Observations
Wednesday
Thursday
LIM Observations
LIM Observations
LIM Observations
LIM Observations
LIM Observations
LIM Observations
Friday
Other Study Components

Water Quality



CWIS Flow



Intake
Aquaria system
Circ Pumps On, Unit
offline
Intake Velocity
Weather and River
Flow conditions
24 and 48 hr
Latent Impingement Mortality
Fish Health
Diagnosis
Preliminary Conclusions


Impingement comprised mostly of shad
24 hr and 48 hr Impingement Mortality > 12%
Limit
Shad (89-100%)
 Non-shad (20-60%)

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Disease prevalence among all survival categories
LIM studies are time and labor intensive
Future Research: Explore ways to optimize
impingement survival
Questions?
Justin Mitchell
(205)664-6184
[email protected]

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