Biological Aspects of OTC Compliance in California

October 15, 2013

John SteinbeckTenera EnvironmentalSan Luis Obispo, CAjsteinbeck@tenera.com

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CA OTC PolicyTwo Options for Compliance

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Track 1 – Reduce intake flow to levels achievable using wet-closed cycle cooling (93% flow reduction) and reduce through screen velocity to less than 0.5 fps

Track 2 – Reduce impingement mortality and entrainment (IM&E) to a level comparable (90%) to Track 1 using operational and/or structural controls

• Must demonstrate Track 1 not feasible (can’t use cost)• Verification monitoring must demonstrate a 84% (90%

of 93%) reduction in IM&E relative to design flow• If compliance based solely on flow the reductions must

be compared on a monthly basis using actual average 2000-2005 flows

• Monitoring required to verify 0.5 fps screen velocity

CA OTC Policy

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• For all plants: Measures must be implemented to mitigate the interim impingement and entrainment impacts resulting from the cooling water intake structure(s), commencing October 1, 2015 and continuing until final compliance.

• Also, 36 months IM&E monitoring required for plants pursuing compliance under Track 2

Achieving Compliance• Compliance will require strategy that

integrates technology and operational measures and maximizes biological data on entrainment– Species and sizes of fish larvae being

entrained will affect choice of compliance technology

– Seasonal and diel patterns of abundance affect options for operational adjustments of flow and decision for use of VSDs

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Achieving Compliance

• Data collected from the large number of studies in CA over the past decade will help inform compliance decisions1. composition, size distribution, and

morphology of fish larvae subject to entrainment

2. seasonal and diel patterns of larval abundance

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Estimating Screen Effectiveness

• body shapes vary among species• species composition varies across facilities

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--------5 mm-------

--------------5 mm------------- -1 mm-

-1 mm-

CIQ goby

white croaker

Estimating Screen Effectiveness

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• Data on lengths and corresponding head capsule dimensions of larvae from numerous studies in CA used to estimate effectiveness of screens at reducing mortality

available at www.waterboards.ca.gov

Estimating Screen Effectiveness

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5 10 15 20

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Gobiidae

Notochord length (mm)

Hea

d di

men

sion

(mm

)

y 0.11x1.074

y 0.08904x1.112

Head heightHead widthHead height eqHead width eq

Parameters from relationship of length and head capsule dimensions used to predict probability of entrainment for various length larvae

Square Mesh OpeningLength (mm) 0.5 mm 0.75 mm 1.0 mm 2.0 mm

1 1 (0) 1 (0) 1 (0) 1 (0)2 1 (0) 1 (0) 1 (0) 1 (0)3 1.000 (0.001) 1 (0) 1 (0) 1 (0)4 0.586 (0.308) 1 (0) 1 (0) 1 (0)5 0.011 (0.019) 0.976 (0.034) 1 (0) 1 (0)6 0 (0) 0.481 (0.246) 0.999 (0.001) 1 (0)7 0 (0) 0.024 (0.028) 0.894 (0.091) 1 (0)8 0 (0) 0.000 (0.000) 0.359 (0.175) 1 (0)9 0 (0) 0 (0) 0.030 (0.027) 1 (0)

10 0 (0) 0 (0) 0.001 (0.001) 1 (0)11 0 (0) 0 (0) 0 (0) 1.000 (0.000)12 0 (0) 0 (0) 0 (0) 0.993 (0.005)13 0 (0) 0 (0) 0 (0) 0.935 (0.035)14 0 (0) 0 (0) 0 (0) 0.722 (0.087)15 0 (0) 0 (0) 0 (0) 0.398 (0.093)16 0 (0) 0 (0) 0 (0) 0.141 (0.050)17 0 (0) 0 (0) 0 (0) 0.035 (0.016)18 0 (0) 0 (0) 0 (0) 0.005 (0.003)19 0 (0) 0 (0) 0 (0) 0.001 (0.000)20 0 (0) 0 (0) 0 (0) 0.000 (0.000)

Estimating Screen Effectiveness

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Studies have also provided extensive data on lengths of larvae susceptible to entrainment – not achievable from one study without very frequent sampling.

Need to account for protection of larger larvae.

Length (mm) Count

Percent of Total

Total Entrainment

Entrainment 0.5 mm

Entrainment 0.75 mm

Entrainment 1.0 mm

Entrainment 2.0 mm

2 56 3.49 3,489,097 3,489,097 3,489,097 3,489,097 3,489,097

3 423 26.36 26,355,140 26,355,140 26,355,140 26,355,140 26,355,140

4 472 29.41 29,408,100 29,393,396 29,408,100 29,408,100 29,408,100

5 424 26.42 26,417,445 15,467,414 26,417,445 26,417,445 26,417,445

6 92 5.73 5,732,087 64,773 5,596,237 5,732,087 5,732,087

7 35 2.18 2,180,685 0 1,047,819 2,178,941 2,180,685

8 23 1.43 1,433,022 0 34,393 1,281,551 1,433,022

9 21 1.31 1,308,411 0 131 470,112 1,308,411

10 22 1.37 1,370,717 0 0 40,436 1,370,717

11 21 1.31 1,308,411 0 0 654 1,308,411

12 5 0.31 311,526 0 0 0 311,464

13 6 0.37 373,832 0 0 0 371,364

14 3 0.19 186,916 0 0 0 174,748

15 2 0.12 124,611 0 0 0 89,956

Totals 1,605 100.00 100,000,000 74,769,819 92,348,361 95,373,564 99,950,648

Percentage Reduction 25.23 7.65 4.63 0.05

Reduction Accounting for Size Structure 76.0 63.5 51.4 6.3

Operational Controls

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Day Night

En-

trai

nm ent

Nu

mb

ers

Patterns of seasonal and diel variation in larval abundance allow for implementation of operation controls that provide large reductions in entrainment

Operational Controls

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Scenario Design FlowAverage 2006-

2010 FlowAverage 2000-

2005 Flow 2006 Flow 2007 Flow 2008 Flow 2009 Flow 2010 FlowBaseline 535,581,158 382,057,085 435,459,372 386,189,970 466,329,811 439,754,839 312,062,188 305,943,010

20% Reduction - VSD 428,464,862 305,645,574 348,367,538 308,952,201 373,063,878 351,803,662 249,649,947 244,754,405% Reduction 20.00% 20.00% 20.00% 20.00% 20.00% 20.00% 20.00% 20.00%Reduction from Design 20.00% 42.93% 34.96% 42.31% 30.34% 34.31% 53.39% 54.30%

50% Night Reduction 364,848,341 269,584,067 302,739,577 267,462,311 320,120,985 308,400,236 225,246,262 226,685,818% Reduction 31.88% 29.44% 30.48% 30.74% 31.35% 29.87% 27.82% 25.91%Reduction from Design 31.88% 49.67% 43.47% 50.06% 40.23% 42.42% 57.94% 57.67%

30% Night - 80% Day 257,731,976 193,172,609 215,647,673 190,224,340 226,855,029 220,449,190 162,833,886 165,497,268% Reduction 51.88% 49.44% 50.48% 50.74% 51.35% 49.87% 47.82% 45.91%Reduction from Design 51.88% 63.93% 59.74% 64.48% 57.64% 58.84% 69.60% 69.10%

We have worked with clients to develop a modeling tool that estimates levels of entrainment reductions provided by varying plant flow by month, hour, or on a diel basis.

Data from three-year monitoring will be useful in verifying that operational controls are providing the necessary entrainment reductions for compliance.

Summary

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John SteinbeckTenera Environmentaljsteinbeck@tenera.com805-541-0310

New and existing biological data on IM&E will be critical in developing a compliance strategy

Questions?