Fish Impingement and Survival on “Fish Friendly” Traveling Water Screens
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Transcript of Fish Impingement and Survival on “Fish Friendly” Traveling Water Screens
Fish Impingement and Survival on “Fish Friendly”
Traveling Water Screens
Alabama Water Resources Association ConferenceOrange Beach, Alabama
September 07, 2012
Justin B. MitchellAPC Compliance Studies
IntroductionImpingement- 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
Withdraw >2 MGD from waters of the US >25% used for cooling purposes
Primary Compliance Options:1. Cooling Towers2. Intake velocity <0.5 fps3. 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 Objectives1. Characterize Fish Impingement
Rates Debris trough Fish trough
2. Evaluate Screen Operational Efficiency
3. Investigate 48 hr Latent Impingement Mortality
4. Examine Rates of Sick or Moribund Fish
Impingement SamplesCollected to Date
Fish Return TroughDebris Trough
3 8-hr sample/day Day Evening Night
4 days/week (Jan-Feb) 2 days/biweek (Mar-Jun) Total Samples = 72 8-hr
samples/trough
Species Diversity 5,300 fish 30 species 11 families Recreationall
y Important spp.
Fragile spp.
Common Species
Shad & Non-shad Composition
80%
0.9%
8%11%
Fish Separation
87.6%
12.4%
92.5%
7.4%
Survivability Experimental Design
Biweekly ImpingementFish Return Trough only
Fish Collection2 days/week
48 Hourly Latent Impingement Mortality (LIM) Observations
Shift Monday Tuesday Wednesday Thursday Friday
0600-1400Fish Collection & LIM Observations
Fish Collection & LIM Observations LIM Observations LIM Observations
1400-2200Fish Collection & LIM Observations
Fish Collection & LIM Observations LIM Observations LIM Observations
2200-0600Fish Collection & LIM Observations
Fish Collection & LIM Observations LIM Observations LIM Observations
Other Study Components Water Quality
Intake Aquaria system
CWIS Flow Circ Pumps On,
Unit offline Intake Velocity Weather and River
Flow conditions
24 and 48 hrLatent 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%)
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