Wallace Dam Relicensing Study Results ... - Georgia Power · Along with this cover letter, this...

Southern Company Generation. 241 Ralph McGill Boulevard, NE BIN 10193 Atlanta, GA 30308-3374 404 506 7219 tel

November 10, 2017 Wallace Dam Project (FERC No. 2413-117) Wallace Dam Relicensing Study Results Meeting Summary – Second Season Ms. Kimberly D. Bose, Secretary Federal Energy Regulatory Commission 888 First Street, N.E. Room 1-A- Dockets Room Washington, D.C. 20426 Dear Secretary Bose: On behalf of Georgia Power Company, Southern Company is filing with the Federal Energy Regulatory Commission (Commission) the Wallace Dam relicensing study results meeting summary for our second season of study in compliance with the Commission’s Integrated Licensing Process regulations at 18 CFR § 5.15(c)(1). Along with this cover letter, this filing consists of the following parts: Attachment A – Study Results Meeting Summary Attachment B – Study Results Meeting Agenda Attachment C – Study Results Meeting Sign-In Sheets Attachment D – Study Results Meeting Presentations Attachment E – Study Results Meeting Transcripts

If you require further information, please contact me at 404.506.7219 or [email protected]. Sincerely, Courtenay R. O’Mara, P.E. Hydro Licensing & Compliance Supervisor Attachments cc: FERC/OEP – Allan Creamer Geosyntec – Steve Layman, Ph.D. Troutman Sanders – Hallie Meushaw, Fitzgerald Veira

mailto:[email protected]

ATTACHMENT A STUDY RESULTS MEETING SUMMARY

Wallace Dam Relicensing FERC No. P-2413-117

Summary of Updated Study Results Meeting

October 17, 2017

Rock Eagle 4H Center 350 Rock Eagle Road, Eatonton, GA 31024

The Project Operations Overview was provided and the results of the Water Resources Updated Study and Aeration Methods to Enhance Summer Dissolved Oxygen in the Wallace Dam Tailrace Area Study were presented.

There were no questions about the studies and no objections to the study methods were raised.

There were no requests for study modifications or additional studies.

The meeting presentations and court reporter transcript for this meeting were filed concurrently with this summary with the Federal Energy Regulatory Commission.

ATTACHMENT B STUDY RESULTS MEETING AGENDA

Wallace Dam / Lake Oconee FERC Relicensing (P-2413-117)

Updated Study Results and Preliminary Licensing Proposal Meetings October 17, 2017

Rock Eagle 4-H Center Sutton Hall

AGENDA

Updated Study Results Meeting (9:00 – 11:30 a.m.):

9:00 a.m. – Introductions, Safety, Review of Operations

9:30 a.m. – Updated Study Results

9:30 a.m. - Presentation of “Water Resources” Updated Study Results (2nd Year)

10:30 a.m. - Presentation of “Aeration Methods to Enhance Summer Dissolved Oxygen in the Wallace Dam Tailrace Area” Study Results

11:30 a.m. – Lunch

Preliminary Licensing Proposal Meeting (1:00 – 3:00 p.m.):

1:00 p.m. - Review of 1st Year Study Results from All Studies

2:00 p.m. – Presentation of Georgia Power’s PLP & Discussion of PLP

3:00 p.m. – Next Steps/Review of Schedule/Adjourn

ATTACHMENT C STUDY RESULTS MEETING SIGN-IN SHEETS

ATTACHMENT D STUDY RESULTS MEETING PRESENTATIONS

Updated Study Results Meeting

October 17, 2017Rock Eagle 4H Center

Introduction

Courtenay O’Mara, P.E.Southern Company

3

Tuesday, October 17, 2017Updated Study Results Meeting: 9:00 a.m. – 11:30 a.m.

• Introductions/Safety/ Review of Operations (9:00 – 9:30 a.m.)• Presentation of “Water Resources” Updated Study Results (9:30 – 10:30 a.m.)• Presentation of “Aeration Methods to Enhance Summer Dissolved Oxygen in

the Wallace Dam Tailrace Area” Study Results (10:30 – 11:30 a.m.)

Lunch will be provided 11:30 a.m.

Preliminary Licensing Proposal Meeting: 1:00 – 3:00 p.m.

• Review of 1st Year Study Results from All Studies (1:00 – 2:00 p.m.)• Presentation of Georgia Power’s PLP & Discussion of PLP (2:00 – 3:00 p.m.)• Next Steps / Review of Schedule/Adjourn

Updated Study Results &Preliminary Licensing Proposal

Meeting Agenda

4

Oct 2017

5

Master Schedule for 2nd Season Study Implementation

Activity Start Date Completion Date or Deadline

Conduct Field Studies:Water Resources October 1, 2016 September 30, 2017Aeration Methods to Enhance

Summer Dissolved Oxygen in Tailrace Area

April 1, 2016 September 30, 2017

File Progress Reports (2nd Season) NA August 31, 2017File Final Study Reports (2nd Season) NA October 11, 2017Hold Study Results Meetings (2nd

Season)October 17, 2017

File Updated Study Results Meeting Summary

November 10, 2017

File Update Study Results Meeting Summary Disagreements

December 11, 2017

File Response to Updated Study Results Meeting Summary Disagreements

January 9, 2018

FERC Resolves Meeting Summary Disagreements

February 8, 2018

6

Project Boundary

Project Recreation Facilities

U.S. Forest Service Recreation Access

Parks Ferry Park

Sugar CreekBoat Ramp

Armour BridgeOld Salem Park

Long ShoalsBoat Ramp

Lawrence Shoals Park

Tailrace Fishing Area

Redlands Recreation Area

Swords Recreation Area

Dyar Pasture Recreation Area

Project Boundary

Downstream Extent of Project Boundary

within Lake Sinclair

Project Operations

Laurie Munn, P.E.Southern Company

8

Project Facilities

Lake Oconee

Powerhouse

Spillway

Flow

Tailrace Fishing

AreaTransmission

Line

9

Oconee River: RM 172.7 Begin Power Delivery: 1979 Number of Units: 6 Production Capacity: 321,300 kW Reservoir Area: 19,050 Acres Normal Full Pool: 435 feet Full Reservoir Storage: 370,000 ac-ft Useable Storage 345,000 ac-ft Normal Operating Range: 433.5 feet to 435.00 feet Average Annual Inflow: 2,037 cfs Operation: Pumped Storage

Project Statistics

10

What is Pumped Storage?

• Move water between two reservoirs located at different elevations.

• Upper reservoir generates power during peak times and pumps water back from lower reservoir during off-peak times.

• Wallace Dam Project operates Lake Oconee as the upper reservoir.

• Sinclair Dam Project operates Lake Sinclair as the lower reservoir.

11

Normal Operations at Wallace Dam

• Powerhouse contains 6 units, 2 conventional units and 4 reversible units.

• Total generating capacity is 321.3 MW

• Generation cycle starts at or near elevation 435 ft. and ends near elevation 433.5 ft.

• During nighttime pumping, Lake Oconee refills to elevation 435 ft.

• Generation is typically highest during the summer months when the electricity demand is the highest.

12

Design Characteristics of the Wallace Dam Units

Unit Nameplate Capacity of Turbines (HP)

Nameplate Capacityof Generators

(MW)

Maximum Hydraulic Capacity (cfs)

Best Gate Hydraulic Capacity (cfs)

Commercial Operation Date

1a 73,000 52.20 8,390 7,200 19802a 73,000 52.20 8,825 7,250 19803 78,000 56.25 8,600 7,900 19804 78,000 56.25 8,600 7,900 19805a 73,000 52.20 8,210 7,250 19806a 73,000 52.20 7,920 7,250 1979Total 321.3 50,545 NA

13

Average Inflows

14

Total Generation 2012 - 2016

Year MW hr % of Generation from Pumpback Annual Inflows

2012 Total 356,364 96.13% Low Inflow

Conventional 13,774 735 cfs

Pumpback 342,590

2013 Total 303,976 72.85% Average Inflow


Pumpback 221,449



Pumpback 257,622



Pumpback 238,811



Pumpback 305,869

15

Wallace Dam Weekly Operations

Normal Inflow Week of 1,591 cfs, Average Annual Inflow = 2,037 cfs

16

Reservoir Elevations-Normal Year 2013

430.00

431.00

432.00

433.00

434.00

435.00

436.00

Jan-13 Feb-13 Apr-13 Jun-13 Jul-13 Sep-13 Oct-13 Dec-13

Lake OconeeDaily Maximum and Minimum Elevations

2013

Daily Maximum Elevation Daily Minimum Elevation

17

Reservoir Elevations-Drought 2007

430.00

431.00

432.00

433.00

434.00

435.00

436.00

Jan-07 Feb-07 Apr-07 Jun-07 Jul-07 Sep-07 Oct-07 Dec-07

Lake OconeeDaily Maximum and Minimum Elevations

2007

Daily Maximum Elevation Daily Minimum Elevation

18

Lake Levels in Recent Droughts

19

Wallace Dam Operations Summary

• Large Reservoir Built for Peaking Power Generation and Pumpback.

• No minimum flow – Wallace Dam discharges directly into Lake Sinclair. There is no riverine stretch between Lake Oconee and Lake Sinclair.

• Reservoir elevation fluctuations are less than 2.0 feet for 100% of the time (433 to 435).

20

Questions?

Updated Water Resources Study

Study Results Meeting

Tony DoddOctober 17, 2017

2

Study Objective – Second Season of Water Quality Monitoring

• Characterize the effects of continued project operation on water quality in Lake Oconee and the tailrace area within the project boundary

• Initial Water Resources Study Report filed in November 2016 presented results of first season of water quality monitoring (Jul 2015 – Sep 2016)

• Updated Water Resources Study Report filed in October 2017 presents results of second season of water quality monitoring (Oct 2016 – Sep 2017), including:

• Continuous tailrace water quality monitoring

• Quarterly reservoir water quality monitoring

3

Study Plan Included Two Seasons (Years) of Water Quality Monitoring

1st Season (2015-2016)

Water quality monitoring in Lake Oconee• Monthly vertical profiles• Quarterly water chemistry• Hourly vertical profiles of summer

pumpback/generationWater quality monitoring in the tailrace• Continuous monitoring of dissolved oxygen

(DO) and water temperature• Hourly transect monitoring of summer

pumpback/generation

2nd Season (2016-2017)

Water quality monitoring in the tailrace• Continuous monitoring of DO and water

temperatureWater quality monitoring in Lake Oconee• Quarterly vertical profiles• Quarterly water chemistry

Initial Water Resources Study Report Updated Water Resources Study Report

4

Study Area

• Lake Oconee and the Wallace Dam tailrace area downstream to the project boundary at Georgia Hwy 16

• 19,050 acres• Classified uses: recreation,

drinking-water and fishing Lake Oconee

Tailrace

Project Boundary

Study Methods

6

Continuous Water Quality Monitoring in the Tailrace

• Same methods as first season of monitoring• Solar powered buoy with remote telemetry

installed July 2015• YSI 6600 data sonde• Continuous (hourly) monitoring of:

• Dissolved oxygen• Water temperature• pH• Turbidity• Specific conductivity

• Routine monthly maintenance• Operated through Sep 30, 2017

Station OCTR – continuous tailrace monitoring was conducted from July 2015 through September 2017

7

Data Analysis for Continuous Tailrace Monitoring

• Continuous DO and temperature data aligned with real-time project operational data

Generation begins

8

Lake Oconee Water Quality Monitoring Locations – Second Season

• Same stations as first season of monitoring

OC1

OC2

OC3

OC4

OC5

OC6

OC7

OC8

OC9

OCTR

StationMainstem Reservoir

Tributary Embayment

Quarterly Vertical Profile

Quarterly Water

Chemistry

OC1

OC2

OC3

OC4

OC5

OC6

OC7

OC8

OC9

9

Quarterly Water Quality Monitoring in Lake Oconee

• Vertical profiles• 9 locations• Measured water temperature, DO, pH,

and conductivity from surface to bottom at 1-meter intervals

• Water chemistry • 6 locations (OC1,2,4,7,8,9)• Grab samples collected at 1-m depth• 12 parameters analyzed

Water Chemistry Parameters

Alkalinity (mg/L)Turbidity (NTU)Magnesium (mg/L)Calcium (mg/L)Hardness (mg/L as CaCO3)Total Phosphorus (mg/L)Nitrate (mg/L)Nitrite (mg/L)Ammonia (mg/L)Chlorophyll a (mg/L)Biochemical oxygen demand (mg/L)Chemical oxygen demand (mg/L)

Study Results – Continuous Water Quality in the Tailrace

11

Summary of First Season of Tailrace Monitoring (2015-2016)

• Continuous water quality monitoring in the tailrace demonstrated DO values below 4.0 mg/L limited to June, July, and first week of August

• Hourly water quality transects in the tailrace showed relatively uniform water quality throughout the study area

• DO values decreased in the tailrace after generation and remained lower until the daylight interim period began, due in part to photosynthesis

12

Daily Average Water Temperature and DO from Over 2+ Years of Monitoring

• Days of monitoring• 2015: 184 days

• 2016: 366 days

• 2017: 273 days• Seasonal variation similar

between years

• Warmer winter water temperatures in 2017

• Lower summer DO concentrations in 2017

2016 20172015

13

Summary of Continuous Tailrace Water Quality Data

Attribute Year 1 (WY 2016)10/1/15 – 9/30/16

Year 2 (WY 2017)10/1/16 – 9/30/17

Hourly readings 8,803 8,712

Days of missing data 3 11

Average temperature 20.2°C (68.4°F) 20.6°C (69.1°F)

Average DO (mg/L) 7.0 7.0

No. of hourly readings <4 mg/L 755 1,216

% of hourly readings <4 mg/L 8.6% 14.0%

14

Tailrace Weekly Plot – November 2016

• DO range: 7.4 – 8.9 mg/L• Temperature range: 20.7 – 22.9°C (69.3 – 73.2°F)

15

Tailrace Weekly Plot – May 2017


16

Tailrace Weekly Plot – July 2017


17

Tailrace Weekly Plot – September 2017


Study Results – Quarterly Water Quality in Lake Oconee

19

Summary of First Season of Reservoir Water Quality Monitoring

• Monthly water quality profiles characterize the extent of mixing in Lake Oconee due to pumped storage operations

• Forebay and other mainstem locations weakly stratified in early summer; completely mixed by August

• Quarterly water quality profiles over many years indicate more complete mixing in mainstem reservoir locations when compared to tributary embayments or upper reservoir stations

• Quarterly water chemistry indicated good overall water quality and mesotrophic conditions

• Hourly water quality profiles in the reservoir indicated temporal stratification during generation and quiescent phases of Wallace Dam operation

20

Quarterly Vertical Profiles, 2016-2017

Station OC1 – Wallace Dam Forebay

21


Station OC2 – Richland Creek Embayment

22


Station OC3 – Mainstem Reservoir

23


Station OC4 – Lick Creek Embayment

24


Station OC5 – Mainstem Reservoir at Hwy 44

25


Station OC6 – Mainstem Reservoir at I-20

26


Station OC7 – Apalachee River Embayment

27


Station OC8 – Oconee River Embayment

28


Station OC9 – Sugar Creek Embayment

29

Quarterly Temperature and DO Profiles,2003-2017

• 2016-2017 profiles consistent with longer history of profile data for Lake Oconee

• Vertical stratification occurs during spring in Wallace Dam forebay (OC1)

• By summer, water column warmer and well mixed due to pumpback operations

• Effects of mixing most evident at OC1 and to a lesser extent at other mainstem reservoir stations

OC1

30

Water Chemistry Analyses Indicate Good Overall Water Quality Conditions

• Results similar to first season of study and data from previous years• Higher concentrations of total phosphorus and turbidity at upstream stations

(OC7, OC8, OC9) indicative of nutrient loading from upstream watershed• Mean trophic state index (TSI) values ranging from 47 to 52 indicate continuing

mesotrophic conditions in Lake Oconee TSI for Lake Oconee, 2014-2017

Trophic state refers to the biological productivity of a waterbody related to nutrients; TSI values can range from 0 to 100

TSI Value Trophic Status

< 30 Oligotrophic

30-60 Mesotrophic

>60 Eutrophic

31

Proposed Nutrient Criteria for Lake Oconee

• Nutrient criteria for Lake Oconee would contribute to improvements in water quality and downstream DO levels in the future

• Georgia EPD is proposing site-specific lake standards that include numeric chlorophyll and nutrient criteria for Lake Oconee to reduce nutrient enrichment from human activities and natural sources in the upstream watershed

• Proposed criteria to include:

• Growing-season average chlorophyll-a limits for the Oconee River arm, the Richland Creek arm, and upstream from the Wallace Dam forebay

• Growing-season average limits in the photic zone for total nitrogen and total phosphorus

32

Updated Water Resources Study Summary

• Continuous water quality monitoring in the tailrace exhibited similar overall seasonal patterns in water quality as the first season of study

• Summer tailrace DO depressions below 4.0 mg/L occurred daily during periods in May, June, July, and August 2017 and were correlated with generation

• Pumpback operations and photosynthesis during interim daytime periods corresponded with increases in tailrace DO values, usually to above 4.0 mg/L

• Seasonal vertical water quality profiles in Lake Oconee showed similar trends as the first season of study, including the influence of pumpback operations on maintaining a well-mixed water column in the forebay during summer

• Water chemistry results indicated good overall water quality in Lake Oconee, mesotrophic conditions, and influences from upstream non-point sources

Aeration Methods to Enhance Summer Dissolved Oxygen in the Wallace Dam Tailrace Area

Study Results Meeting

Steve LaymanOctober 17, 2017

2

Study Objectives

• Identify and evaluate, using data collected during the first season of study, technically feasible and cost-effective aeration methods for increasing summer dissolved oxygen (DO) levels in the Wallace Dam tailrace area

• Tailrace monitoring in 2015-2016 found that generation correlated with DO depressions below 4 mg/L during June-early August periods

• Second season of tailrace monitoring in 2016-2017 since detected DO depressions below 4 mg/L during May-August periods

Lake Oconee

Google Earth

OCTR

3

Assessment Approach

Aeration Methods Assessment

• Characterize and model the water withdrawal zone at the turbine intakes

• Screen full range of aeration alternatives for technical feasibility and efficacy

• Model turbine aeration to assess the potential for turbine venting and the addition of forced air

• Model in-lake aeration approaches at the conceptual level of design

Oxygen Diffuser System Site Visit

• Visit two in-lake oxygen diffuser systems operated by the U.S. Army Corps of Engineers (USACE) in large reservoirs on the Savannah River

4

Aeration Methods Assessment

• Performed by a team of highly experienced water quality management specialists:

• Richard J, (Jim) Ruane, M.S., of Reservoir Environmental Management, Inc.

• Mark H. Mobley, P.E., of Mobley Engineering, Inc.

• Paul J. Wolff, Ph.D. of Wolffware, Ltd.

• Experts in water quality, modeling, and aeration; formerly with Tennessee Valley Authority (TVA)

• Assessment report provided as Appendix A

5

Study Area

• Wallace Dam, the lower end of Lake Oconee just upstream of the dam (the forebay), and the Wallace Dam tailrace area downstream to the project boundary at Georgia Highway 16

Project Boundary

Lake Oconee

Tailrace

Forebay

Study Methods

7

Withdrawal Zone Analysis

• Reviewed water quality monitoring data and bathymetry• Applied hourly vertical profile data to develop a withdrawal

zone model using USACE Waterways Experiment Station SELECT model

• Characterize vertical extent of forebay withdrawal zone under different flow scenarios

• Predict DO concentrations in the penstock• DO enhancement target defined as difference between

inflow DO value and numeric DO criteria for the tailrace

• 5.0 mg/L daily average, 4.0 mg/L instantaneous

Station OC1 (Forebay)Hourly Profile Data, 7/27-28/2016

Generation 2p-7pInterim 7p-1amPumpback 1a-7a

8

Screening of Alternative Aeration Methods

• Evaluated range of ten different DO enhancement methods applied at other hydropower projects

• Screened for technical feasibility and efficacy for improving summer DO concentrations in the Wallace Dam tailrace

Source: USDOE

Turbine Venting

Source: Mobley

Forebay Surface Water Pumps

9

Detailed Analysis of Two Most Feasible Aeration Alternatives

Forebay oxygen line diffuser system• Forebay bubble plume model developed to evaluate conceptual design• Withdrawal zone model was used to develop design inputs

Draft tube aeration using compressed air• Discrete Bubble Model set up for Wallace Dam draft tubes• Model calibrated using 2015 and 2016 water quality data• Simulated DO uptake over range of operations and water quality conditions to

determine how much air flow needed to achieve DO improvementsComparative Analysis

• Estimated installation and annual operation costs• Considered practicality of system deployment and maintenance

10

Oxygen Line Diffuser System Site Visit

• Georgia Power visited two oxygen line diffuser systems on the Savannah River

• J. Strom Thurmond Lake

• Richard B. Russell Lake

• Similar in overall design to concept evaluated for Wallace Dam

• Site visit conducted on August 3, 2017, when both systems operating

Richard B. Russell Lake

J. Strom Thurmond Lake

Lake Oconee

Results

12

Summer Vertical Profiles in Forebay

• Prevailing trend during operations:

• Complete vertical mixing of water column during pumpback at night

• Gradual stratification during interim period following pumpback

• Increasing stratification during generation; highest DO values and warmest temperature water near surface

Forebay (OC1) Hourly Profile Data, 7/27-28/201

Generation Pumpback Generation Pumpback

Source: Ruane, Mobley, and Wolff (2017)

13

Generation Withdrawal Zone

• Intake draws generation flows primarily from the upper layers of the forebay, even though the centerline of the intake is 70 feet deep

• As generation flows increase, the withdrawal zone shifts to higher in the water column


14

Review of Alternative Aeration Methods (Page 1 of 2)

MethodTechnically Feasible?

Turbine venting – passive venting of air into draft tubes; pressures in draft tube prevent air from being drawn in passively

No

Forebay oxygen line diffuser system – oxygen bubbles passively diffuse into reservoir through porous hose installed in forebay

Yes

Forebay surface water pumps or mixing units – pumps blend high-DO water near surface with low-DO water near withdrawal zone; limited benefit at Wallace Dam because withdrawal zone already draws from upper water column and pumpback operation mixes water column vertically

No

Draft tube aeration using compressed air – adds air to draft tubes using compressors; would allow for acceptable gas transfer efficiency

Yes

Forebay aeration line diffuser system – air diffuses into reservoir through porous hose using compressed air; requires much larger and more costly system than forebay oxygen line diffuser system

No

15

Review of Alternative Aeration Methods (Page 2 of 2)

MethodTechnically Feasible?

Forebay mixing system – mixes water column by upwelling bottom waters into upper layers; mixing induced by pumpback eliminates any benefit of forebay mixing system

No

Forebay skimmer devices – placement of barrier (e.g. submersed weir, curtain) along channel bottom upstream of intake to limit withdrawal zone to high-DO water near surface; withdrawal zone already draws from upper water column

No

Multi-level intake structure – intake allowing selective withdrawal from water levels in reservoir; insufficient to meet DO objectives after pumpback, costly, and unlikely to work with existing pumpback turbines

No

Tailwater aeration structures – aeration weirs or structures that aerate water as it passes and drops in elevation; not feasible due to obstruction of pumpback flows

No

Side-stream supersaturation system – pumps side stream of flow through oxygen transfer device (e.g., Speece Cone), where gaseous oxygen injected and dissolves under high pressure; then flow blended back into waterbody; determined to be too costly in previous hydropower applications

No

16

Forebay Oxygen Line Diffuser System

• Places oxygen in a reservoir in areas of low DO to meet a target DO concentration in the dam releases

• Porous diffuser lines spread oxygen bubbles over large area

• Systems currently being operated at 15 hydropower projects in U.S.

• Applications in the Southeast include 9 TVA reservoirs, 2 USACE reservoirs, and Duke Energy’s Tillery development Source: Ruane, Mobley, and Wolff (2017)

17

Components and Features of Oxygen Line Diffusers


18

Conceptual Design of Forebay Oxygen Line Diffuser System for Wallace Dam

• Two sets of diffuser lines about 0.7 mile long for operational flexibility

• Upstream set to inject low level of oxygen continuously to maintain oxygenated forebay volume during non-generation

• Downstream set to boost oxygen output during generation

• Diffuser lines placed at various levels above bottom to optimize aeration of withdrawal zone

• Maximum oxygen capacity of 200 tons/day for worst-case conditions; median use of 60 tons/day


19

Cost Analysis of Forebay Oxygen Line Diffuser System at Wallace Dam

Estimated Capital Cost Estimated Annual Liquid Oxygen Costs

$4,699,000 $150,000 to $240,000

• Includes diffuser lines, supply lines, and liquid oxygen storage and supply facility

• Based on tailrace monitoring data for 2015 and 2016

• Up to 8 or 9 tanker trucks would deliver liquid oxygen each week during peak oxygen demand periods

20

Oxygen Line Diffuser System Site Visit to USACE Reservoirs

• On-shore elements of J. Strom Thurmond aeration system:

Liquid Oxygen Tanks and Piping Vaporizer System Oxygen Flow Control Valves

21

Draft Tube Aeration Using Compressed Air

• Active design using compressors/blowers to force air into the draft tube immediately below the turbine units

• Air-water mixture passes through draft tubes prior to being released into the tailrace

• Pressure and time of water passage would allow for acceptable gas transfer efficiency at Wallace Dam

• Potential limitations include loss of unit efficiency from blower operation and excessive TDG in draft tube releases

Draft Tube Tailrace

Forced Air

22

Conceptual Design of Draft Tube Aeration Using Compressed Air

• Discrete Bubble Model used geometry of draft tube to simulate gas transfer through draft tube to the surface of the tailwater

• Model predicted airflows required to achieve DO target of 5 mg/L daily average and resulting TDG levels

• Airflows moderated to reduce energy losses and levels of TDG• Estimated sizes and numbers of compressors required, piping, and electrical work


23

TDG Considerations for Draft Tube Aeration Using Compressed Air

• TDG results from air mixing in water; nitrogen (N) accounts for 78% of atmosphere, oxygen 21%; forced air also increases dissolved N in turbine releases

• Turbine releases can become supersaturated with dissolved gas• Background TDG can exceed saturation by 5 to 25% in turbine releases

• Sensitivity analysis bracketing range of dissolved N levels indicated TDG supersaturation could exceed 110% a substantial portion of the time


24

Cost of Draft Tube Aeration Using Compressed Air

• In addition to high costs, other potential issues for use of this method at Wallace Dam included elevated levels of TDG, maintenance costs, and noise of the blowers

Estimated Capital Cost Estimated Annual Costs

$15,190,000 $140,000

• Assumes two blowers per turbine• Includes quotes from equipment

manufacturers and sizing based on evaluation of historical DO data

• Does not include piping design and more site-specific information

• Due to losses in net generation

25

Conclusion

• A forebay oxygen line diffuser system is the most technically feasible and cost-effective approach for enhancing summer DO concentrations in the Wallace Dam tailrace

• Benefits of forebay oxygen line diffuser system:• Installation costs $10 million less than draft tube aeration

using compressed air• No modifications to powerhouse or turbines

• No impacts to unit efficiency or operations

• Avoidance of TDG concerns in turbine releases

26

Aeration Methods Study Summary

• Ten aeration approaches were reviewed and evaluated for their technical feasibility and efficacy for enhancing summer DO conditions in the Wallace Dam tailrace

• Conceptual designs were developed and installation costs estimated for two alternatives identified as being technically feasible:

• Forebay oxygen line diffuser system• Draft tube aeration using compressed air

• A site visit of two oxygen line diffuser systems in large reservoirs provided valuable insight into the practicality of system deployment

• The study concluded that a forebay oxygen line diffuser system would be the most technically feasible, cost-effective, and practical approach for enhancing summer DO concentrations in the Wallace Dam tailrace area

ATTACHMENT E STUDY RESULTS MEETING TRANSCRIPTS

TSG Reporting - Worldwide 877-702-9580

Page 1

1

2

3

4

5

6

7

8

9

10

11 WALLACE DAM/LAKE OCONEE

12 FERC RELICENSING (P-2413-117)

13 UPDATED STUDY RESULTS AND PRELIMINARY LICENSING

14 PROPOSAL MEETING

15

16 10-17-2017

17

18

19

20 PRESENTERS: Todd Dodd

Dr. Steve Layman

21

22

23 REPORTED BY: TANYA L. VERHOVEN-PAGE,

CCR-B-1790

24

25 FILE NO. 132042


Page 2

1 FERC MEETING

2 EATONTON, GEORGIA; TUESDAY, OCTOBER 17, 2017

3 9:38 A.M.

4

5 P R O C E E D I N G S

6

7 MS. O'MARA: Okay. Thank you,

8 Laura. So now we're going to go ahead

9 and move into the updated study results

10 presentations. Our first one up will be

11 water resources and second is aeration

12 method.

13 So I think Tony is going to be our

14 presenter for water resources, and I just

15 realized I had not pulled his up in

16 advance, but I will do it now.

17 So this is Tony Dodd. He's our

18 water resources expert within Georgia

19 Power.

20 MR. DODD: Good morning, again

21 everybody.

22 MS. O'MARA: Good morning.

23 MR. DODD: Again, I'm Tony Dodd

24 here to represent the updated water

25 resources study which was designed as a


Page 3

1 FERC MEETING

2 two-year study.

3 The study objective -- so during

4 the second season monitoring was to

5 characterize the effects of continued

6 projection of operation on water quality

7 in Lake Oconee, and within the projected

8 boundary the first was submitted in

9 September 2016, and last year we

10 presented the results of that study which

11 carried us from July '15 into the end

12 of -- in between September of 2016 last

13 year.

14 The second season or second year of

15 studies really picked up where that one

16 had left off and terminated in the

17 September that we just left behind, and

18 the main study components in the second

19 year study were, again, to continue to

20 look at water quality and tailrace of the

21 dam to monitor that in a continuous way

22 and also to look at the -- to really a

23 continuation of what we were doing for

24 years past with our typical reservoir

25 monitoring program to, again, collect


Page 4

1 FERC MEETING

2 quarterly reservoir quality data, which

3 actually that second point wasn't

4 actually required in our first approved

5 study plan, but since it's what we

6 normally do anyway, it continued a longer

7 data set and gave us more data for

8 comparison.

9 So each of those years included

10 monitoring in the reservoir as well in

11 the tailrace. The first year included

12 collection of monthly vertical profiles

13 in the lake, otherwise characterizing the

14 water column with certain data parameters

15 and poor water quality chemistry and two

16 intensive summertime studies where we

17 looked hourly on changes and dissolved to

18 try understand the affects of the pump

19 back and the generation cycles on water

20 quality, the water profile upstream of

21 the dam with those operation changes, and

22 then tailrace again.

23 That first year we're looking at in

24 the continuous way dissolved oxygen and

25 water temperature and tailrace, and they


Page 5

1 FERC MEETING

2 were also intensive surveys there done on

3 top that to look at hourly changes with

4 operations. The second season has a

5 little more focus to what we learned in

6 the second season. The focus continued

7 with the water DO and water temperature

8 and also the vertical profiles of water

9 chemistry on a quarter basis.

10 The lake's classified uses are for

11 recreation, drinking water and fishing,

12 and among those uses there are water

13 quality standards that support those, and

14 one of those standards is in regard to

15 dissolved oxygen.

16 The state standard for dissolved

17 oxygen instantaneous concentration not to

18 fall below 4.0 milligrams per liter or

19 the daily average that's greater than 5.0

20 milligrams per liter, and I mention that

21 here specifically because that's really

22 the focus of our tailrace monitoring

23 results later. So you'll see reference

24 to the 4.0 milligrams liter

25 instantaneous, DO or dissolved oxygen


Page 6

1 FERC MEETING

2 concentration.

3 As for the study methods, they were

4 really the same in the second year as

5 they were in the first year.

6 In the tailrace shown here in this

7 photographs -- you can see a buoy in the

8 foreground and a dam in the background.

9 We refer to this station as OCPR for

10 Oconee tailrace. The buoy is

11 solar-powered and was able to remotely

12 telemeter or send out data so people

13 could monitor the DO from their desktops

14 many miles away and look at realtime

15 what's happening during the course of the

16 day. The type of equipment we use is

17 YSI. It's sort of a common type of

18 equipment used for lake study, and,

19 again, the data collection was

20 continuously or hourly. That's what we

21 mean by continuous in this case is

22 hourly, and we looked at these several

23 parameters, dissolved oxygen, water

24 temperature, pH, the turbidity and the

25 conductivity, as well, and, of course,


Page 7

1 FERC MEETING

2 with any equipment -- especially around

3 lakes, they need routine maintenance, and

4 anyone who has done lake work knows their

5 uphill battles with maintenance and

6 equipment, and this was no exception. We

7 did have a few dates where we were able

8 to attach the -- whatever the air logs

9 it, whether it was in the data logger or

10 some physical ailment with the buoy, the

11 realtime telemetry allowed our crews to

12 get out there and fix those things right

13 away and keep it going, and, of course,

14 we've operated that through -- through

15 just September this last month.

16 I'm going to pause on this map just

17 for a second just to set up -- you're

18 going to see a few more graphs like this

19 later, but the goal of collecting data

20 from the tailrace in a continuous way is

21 to not only have the data and look at the

22 concentrations and changes and the actual

23 data for temperature and DO or -- but

24 also to align it, synchronize it with our

25 operations during the same period, but


Page 8

1 FERC MEETING

2 this is an example graph, probably a

3 snippet of data from the year before,

4 where we show concentrations and trend

5 lines for water temperature in red and

6 dissolved oxygen in blue, and the units

7 of measure for those are on the left-hand

8 axis, and through time, which is on the

9 horizontal axis, those are days of the

10 week, and that's overlaid with our

11 operations, and, again, I'll just pause

12 for our second so you understand at a

13 glance of what this is about later when

14 you see the other graphs. Where the bars

15 are lightly colored, there are smaller

16 increments -- smaller increments within

17 this bit bar set.

18 Each increment represents an hour

19 of operation followed by no bars. Really

20 there's no operation in here. It's a

21 quiet or a quiescent period where there's

22 no generation of pump back, and then the

23 next period is generation in the gray

24 bars, also hourly increments during the

25 time it's generated, and then for the


Page 9

1 FERC MEETING

2 amplitude or output of the generation or

3 pump back the right hand axis tells us

4 how many units were operated for any

5 given period of time, and then, of

6 course -- and we'll talk about these

7 later what we see on the graphs, but

8 there are certain responses in the trend

9 line to whether we were pumping back or

10 generating or not operating at all.

11 Also, one last feature is where the graph

12 is labeled at a tick mark, that's the

13 beginning of a 24-hour period, and so

14 this would be at midnight and following

15 to noon to the next day and then into the

16 evening of the next night.

17 Turning our attention to the lake

18 water quality monitoring, there were nine

19 stations that were in use throughout Lake

20 Oconee for the water quality monitoring.

21 The table on the left shows how those

22 sampling locations were distributed.

23 Some were in the main stem of the

24 reservoir. Obviously the original

25 reading flow of the waterway, and a


Page 10

1 FERC MEETING

2 number of those were in tributary

3 embedments, and the idea, of course, is

4 to have something that's representative

5 of the -- through the bathymetric and

6 habitat changes of the reservoir. So we

7 get a good overall picture, and for water

8 quality profiles, it reflected

9 quarterly -- the samples were taken every

10 month, and -- or I'm sorry every

11 location, rather, and then during

12 quarterly water chemistry, there was a

13 subset of those nine locations that were

14 designed still to capture information

15 about main stem locations or tributaries

16 or even like a major confluence so we

17 could detect changes in the water, and or

18 the tenth station was -- I mentioned

19 earlier -- was OCTR, the tailrace

20 location, and I'll point out, too, that

21 the data that we collected in tailrace

22 was collected at 1 meter depth.

23 One meter is where the State

24 standard is measured. So the buoy is

25 collected at about a meter, and also when


Page 11

1 FERC MEETING

2 the intensive surveys are done hourly

3 from above with a roving piece of

4 equipment in the tailrace, those are also

5 at 1 meter so we could have some basis

6 for comparing the data that we see to the

7 State criteria.

8 For the water quality monitoring of

9 the lake, as I mentioned, the profiles

10 are in all nine locations, and we

11 collected information with this

12 electronic equipment. It's a multi-ray

13 probe. One lowers to depth, and each

14 liter interval from the surface to the

15 bottom we electronically record

16 information for dissolved oxygen, pH, and

17 temperature and conductivity. For water

18 chemistry at that subset location shown

19 here it's really a discreet sample. It's

20 a water collection device that literally

21 grabs an alga, a sample from that depth,

22 and then that's handled in a laboratory

23 way in a chain of and custody and sent to

24 a lab for analysis, and they are analyzed

25 through these 12 parameters. These


Page 12

1 FERC MEETING

2 twelve parameters are pretty classic in

3 their application from looking at the

4 general health and water quality

5 condition. There are parameters here

6 that speak to chemical nature, physical

7 nature, particularly with turbidity,

8 light penetration and also some

9 biological measures along with nutrients.

10 So I'll jump back now. We're going

11 to talk about the results from the water

12 quality in the tailrace -- from the

13 tailrace monitoring. And I'm going to

14 back up one step more and sort of capture

15 where we left off in the first year,

16 which is really a summary point of what

17 we learned after the first year. All

18 that data that we collected in the first

19 year it demonstrated that we have DO

20 values that sank below that instantaneous

21 4.0 milligrams per liter criteria, and

22 when it occurred, it was limited to these

23 summer months. It's when it's the

24 hottest time of the year, and it's when

25 we expect to see DO depressed, generally


Page 13

1 FERC MEETING

2 speaking, in surface waters, and we'll

3 talk more about that as we go, but when

4 it occurred, it was in June, July and the

5 early part of August, and in the

6 tailrace, the hourly transects shows the

7 uniform quality throughout the area.

8 What that means is when we were roving

9 with a boat with a piece equipment at a

10 meter deep, while we were generating and

11 collecting information from the dam all

12 the way down to Highway 16, wherever we

13 went, there wasn't much change in the

14 apparent DO or temperature, and then

15 during another period -- maybe during --

16 maybe when we're not pumping back or

17 generating an intensive hourly data

18 collection through that area, even though

19 the DO and temperature might be different

20 during that non-operational period, there

21 was very little change throughout that

22 whole 6,000-foot reach or whatever it is.

23 That's really what that means. And then

24 overall, the big picture take away from

25 that first year, was that when the DO


Page 14

1 FERC MEETING

2 values decreased in the tailrace with and

3 after generation, they usually would

4 remain lower until daylight hours, and we

5 would see a DO begin to recover, due in

6 part to photosynthesis, and there's a lot

7 of other things that can be in play

8 depending on environmental conditions

9 that day. Maybe it's raining, maybe it's

10 cloudy, maybe there's a wind-driven

11 surface turbulence. Obviously, it's

12 going to the effect DO near the surface.

13 So we see variations, and later, when we

14 look at these graphs where we have bars

15 and peaks and trends, if you see little

16 bumps between the valleys, sometimes it

17 could be explained by those little daily

18 occurrences of changes in the water and

19 the weather conditions.

20 So looking back over the whole

21 two-year period or two and a half year

22 period, really, for monitoring in the

23 tailrace, in 2015 there's a bunch of days

24 of monitoring. 2015 184 days out of that

25 year every day in our 2016 leap year we


Page 15

1 FERC MEETING

2 were collecting data, and in 2017, 273

3 days which culminated here in the end of

4 September that I mentioned a little while

5 ago.

6 What we learned -- this graph is

7 showing us the relationship between

8 dissolved oxygen in blue and the water

9 temperature in red. And is you see the

10 seasonal variation between those years,

11 and really what this speaks to is what is

12 known about just oxygen solubility in

13 water.

14 When water temperatures are warmer,

15 they hold less temperature. When water

16 temperatures are cooler, they hold more

17 oxygen, and so this is reflecting that

18 seasonal trend throughout the year, and

19 this is what you expect to see looking at

20 water data from any lake or deep pond in

21 our area.

22 We learned from the graph that --

23 in analyzing the data at a closer level,

24 that the winter temperatures were a

25 little bit warmer in 2017 and also the DO


Page 16

1 FERC MEETING

2 in the summer, this past summer -- the

3 second year -- were also lower than in

4 the first year.

5 So -- and I'll point to another

6 thing, if I may. This is the dissolved

7 oxygen again. Here is the 4-milligram

8 per liter line. You can see during parts

9 of the year where clearly the

10 instantaneous values steep below that,

11 but if you look at the graph, those are

12 usually associated with those -- with

13 those warmer periods, and another way to

14 look at the summary -- summary of the

15 data is that we collect a similar number

16 of readings between both of those years

17 in the tailrace. There were a few days

18 of missing data that we addressed as well

19 as we could with typical range or array

20 of -- maintaining equipment.

21 The average temperature was

22 slightly higher in the second year. The

23 average dissolved oxygen over the entire

24 monitoring periods, each period was the

25 same. The number of hourly readings that


Page 17

1 FERC MEETING

2 were below that 4.0-milligram per liter

3 were higher in year two than in year one,

4 and then the relative percentage, among

5 all the data points that were recorded,

6 14 percent of those were below four in

7 the second year and 8.6 percent of

8 those -- all those readings were below

9 four in the first year.

10 So here is one of -- one of those

11 graphs that we stopped to talk about a

12 few minutes ago. There's a series of

13 four here, and the scale -- units of the

14 measurements of the scale might change

15 slightly from slide to slide, but it's

16 the same basic information.

17 What I want to show you is where we

18 left. Again, with this graph, this is

19 where we left off at the end of the first

20 year of study, and I'll take you to --

21 from this cooling period in November to a

22 warmer period the following spring to the

23 hottest part of the year in the summer

24 and back up into the fall as our ambient

25 conditions changed, and you'll see the


Page 18

1 FERC MEETING

2 change in dissolved oxygen and

3 temperature in those line graphs as we go

4 through those four different figures, and

5 we'll also look at some of the trends

6 there.

7 So, at first glance, one could

8 readily see how this is -- early to mid

9 November how just generally depicted by

10 the red line how temperature is starting

11 out in the 22-degree, 23-degree Celsius

12 range and starting cool. This is just

13 the effect of seasonal cooling just of

14 the course of just one week, and DO range

15 during this period of time was 7.4 to

16 8.9 milligrams per liter, and the other

17 thing I think that jumps out right away

18 are these apparent peaks and declines,

19 and you'll notice here -- and you'll see

20 it other graphs, too, everywhere where

21 there's a peak, it's usually in a period

22 where there's no generation or pump back,

23 and then there's a very steep decline in

24 dissolved oxygen typically when

25 generation begins. So what we're seeing


Page 19

1 FERC MEETING

2 in this graph -- and we'll it in the

3 others -- is the effect of the

4 correlation or generation between -- or

5 generation period and what we see in the

6 water quality. We're just passing water

7 at that time from the dam down passed the

8 tailrace and past this buoy, and we're

9 detecting that.

10 So during a non-generation period,

11 one can actually see where dissolved

12 oxygen actually begins to -- actually

13 begins to recover in -- during the pump

14 back cycle where we turn on the pump back

15 units and pump from St. Claire back into

16 Oconee. The DO is at least stable if not

17 increasing. Remember we're pulling

18 shallower surface waters from St. Claire

19 now back up into Oconee when we're taking

20 that change, but as we're -- when we're

21 finished with that period and we shut off

22 the pump back, it's this quiet phase in

23 the tailrace of Lake St. Claire, and this

24 is during the peak daytime. So during

25 the day we're getting surface warming.


Page 20

1 FERC MEETING

2 You're getting natural solution and

3 mixing in the surface layers of Lake

4 St. Claire. Whatever is driving the DO

5 here is undoubtedly related to

6 photosynthesis, as well. The alga

7 community makes oxygen and sunlight and

8 it respires oxygen in the acid in some

9 way.

10 So this is a typical -- some of

11 this is sort of overlaying by the typical

12 photosynthesis DO by day and respiration

13 and consuming DO by night, and you'll see

14 that same theme throughout.

15 So, again, November. We move into

16 the spring of the next year. Right away

17 you can see how the DO generally is

18 lower, temperatures are higher, same sort

19 of peaks and valleys. Some of those

20 little bumps that might change daily with

21 weather changes or wind changes. Some of

22 the instantaneous valleys now by May --

23 late May are dipping below that 4.0

24 milligrams per liter criteria, and then

25 in summer, things have really warmed up


Page 21

1 FERC MEETING

2 now. Now we're up to almost 31 degrees

3 at times during this representative week

4 here in mid August. And the DO is 1.5 to

5 4.9. Of course, the blue line readily

6 conveys how the water we're seeing is

7 coming through the dam generation and

8 it's definitely lower, but the same sort

9 of peaks and trend with some increase in

10 pump back, a lot of increase in DO during

11 the hot and sunny part of the day, and we

12 generate, and we see the water again

13 comes through the dam through the

14 tailrace, and then by September, I guess,

15 we're getting some relief now from the

16 summer temperature effect. Temperatures

17 are now back down between 70 and 90

18 degrees, and the DO is correspondingly

19 now higher as it was in the fall before,

20 and the same things are appearing.

21 So real quickly I thought this was

22 interesting, even though the -- even

23 though -- the scale on these graphs it

24 changes a little bit. You'll get the

25 idea. I'll scroll through these real


Page 22

1 FERC MEETING

2 quickly, and if you watch the blue line,

3 you can see how it changes from fall to

4 summer and back up. You can see the

5 effect of the season on DO. It gets

6 lower, lower and then by September it

7 starts to recover.

8 As for the quarterly water quality

9 stamping in the lake, we'll capture a

10 little bit of that first season, too,

11 what we learn in the first season before

12 we talk about the second season. The

13 monthly profiles that were collected in

14 told us something about the extent of

15 mixing up in Lake Oconee. In other

16 words, the literal mixing that happens

17 when water is pumped back from St. Claire

18 up to Lake Oconee.

19 Also the forebay and mainstream

20 locations they are weekly stratified in

21 early summer. We'll learn more about

22 that in the next few graphs, and then

23 it's completely mixed by August.

24 The quarterly profiles -- we look

25 at 15 years of Georgia Power profile data


Page 23

1 FERC MEETING

2 to do a more detailed comparison with,

3 and we can clearly see where there's a

4 lot more just mixing effect from the

5 pumping and moving of water in the main

6 stem locations as compared to an

7 embayment, which doesn't have that kind

8 of connection to the main land or even

9 way upstream in the upper tributaries.

10 In fact, that the upper reservoir

11 stations have their own dynamic. They're

12 shallower. It's more of a constant

13 flowing condition. There are stumps and

14 bridge pilings and things that complicate

15 those upper tributary locations, but they

16 are different than the main stem. They

17 don't have the same mixing effect, and on

18 a quarterly basis there are also

19 chemistry samples demonstrated in the

20 lake. Overall it has a good water

21 quality, and it results in this

22 mesotrophic condition. It's a condition

23 which speaks to the state of productivity

24 in the lake, and we'll touch on that,

25 too, in a few minutes, and the hourly


Page 24

1 FERC MEETING

2 profiles. These were the more intensive

3 data collection that was made a vertical

4 water column at these locations in the

5 reservoir indicated this temporary

6 stratification during generation and

7 quiet periods when we weren't generating.

8 So stratification means that typically --

9 and you'll see it in a couple of graphs

10 here. Typically in the summer, when the

11 reservoir warms, the warmest waters in

12 the lake buoy to the surface, and the

13 colder -- deeper waters are colder and

14 are more dense, and you'll see a

15 corresponding effect on temperature.

16 Higher temperatures at the top and lower

17 temperatures at the bottom, and also not

18 only temperature but the effects of all

19 the oxygen demanding constituents that

20 are in the lake. Dissolved oxygen shows

21 a similar profile on the stratification

22 in the summer. Higher levels near the

23 surface and lower concentrations near the

24 bottom. That's what that speaks to.

25 We'll move onto the -- a couple


Page 25

1 FERC MEETING

2 graphs that speak to the second year of

3 study. On the left-hand side, the main

4 graph is -- is depicting a horizontal

5 profile -- quarterly profiles of water

6 temperature with depth on the left-hand

7 axis and temperature across the

8 horizontal axis, and it's corresponding

9 it's counterpart with dissolved oxygen at

10 those same depths at the same time, and

11 right away you can see where the blue

12 line, which is a time period in the

13 spring, when we were out in the

14 springtime recording the information, the

15 lake has this stratified effect that I

16 was just talking about where you have

17 higher temperature, higher concentrations

18 near the surface and at depth, it tends

19 to taper off and with lower concentration

20 and lower temperature, but really

21 interestingly -- and this speaks to the

22 mixing effect that I was just talking

23 about a few minutes ago. The orange line

24 is for mid summer. This is the time of

25 the year when the stratification in a


Page 26

1 FERC MEETING

2 reservoir that's not influenced by pump

3 back has a much more severe

4 stratification effect. Otherwise normal.

5 So here the gold line or summary is just

6 telling us that the condition at the

7 forebay in front of the dam are just

8 completely mixed from top to bottom.

9 Same temperature, same DO top to bottom.

10 In contrast, if you go to a part of the

11 lake that's not affected by a mixing,

12 pump back mixing. Like here this is in

13 Richland Creek shown on the map off to

14 the side. Same set graph set. You can

15 see here that in spring the

16 stratification begins to set up as we

17 normally expect to see, and by summer

18 it's just even more severely set for the

19 season, and then by fall in the red line,

20 as the lake mixes, surface temperatures

21 cool, the water column mixes, we see

22 really the same DO and temperatures

23 distributed throughout the water column.

24 Again, that's just normal. That's what

25 you expect to see for lakes and lake


Page 27

1 FERC MEETING

2 flood mixing under the conditions without

3 a pump back influence.

4 So these are some graphs. There

5 are a number of these. I'll go through

6 some of them more quickly because they

7 are very similar, but the ones thing I

8 wanted to point out as we go, the ones in

9 the main stem show more of the mixing

10 effect in the summer, and the ones that

11 are off stream or in the tributaries tend

12 to show more of the stratification

13 effect, and the same thing, too,

14 particularly in the shallow stations

15 here, we'll see near the end of this

16 series of the seven or eight slides, in

17 the shallow stations, those are more

18 readily effected by these daily

19 influences of temperature and rain and

20 whatnot. So -- and usually they are

21 shallower. There's not a lot to see, but

22 we'll go through these pretty quickly.

23 This is station OC-3. This is about five

24 and a half miles upstream to Wallace Dam,

25 and here we can see the stratification


Page 28

1 FERC MEETING

2 effect particularly with DO. Not so much

3 with temperature.

4 So this is indicating that there's

5 some things, probably the biological and

6 chemical constituents that are affecting

7 the dissolved oxygen in the absence of

8 light near the bottom, and yet the water

9 is a bit mixed because of -- as you can

10 see in the temperatures, and the other

11 thing that's unknown, when we look at

12 these, we'll look for subtle changes or

13 explanations why one profile looks

14 different than the other. I don't know

15 what time of day necessarily that profile

16 was collected. Whether it was near the

17 end of the day versus the middle of the

18 day or in the middle of a quiet period or

19 just at the end of a generation period,

20 it could alter that slightly. But the

21 point is that there's some mixing going

22 on in the main stem. OC-04 that's over

23 in Lick Creek. Also shown off to the

24 west side of the lake on -- in the

25 figure.


Page 29

1 FERC MEETING

2 It's an embayment so we expect to

3 see a mixing in the stratification in the

4 spring and summer, which we do here.

5 Another main stem location Highway 44.

6 Those who know the lake know the lake

7 really narrows down at that point. When

8 the water is moving, whether it's pump

9 back or flowing, it actually has sort of

10 a physical confining or mixing effect

11 there at Highway 44. So that's probably

12 playing a role in why we see the profiles

13 the way we do here. The same thing.

14 Interesting in spring, the lake is trying

15 to set up and start a stratified

16 condition, but the effects of pump back

17 or normal a pump back operations mix that

18 by summertime. This is another main stem

19 location much further up at the I-20

20 bridge. This is one of those areas

21 that's more dynamic with shallows and

22 in-flows. Another embayment. This is

23 the same stratifying effect. Oconee

24 River at the upper end above I-20 very

25 shallow. Not much to see. Nevertheless


Page 30

1 FERC MEETING

2 we can still see how it's stratified.

3 Anybody who has been swimming in the lake

4 in the summer, you hot in the hot water

5 and you feel the cold water in your toes.

6 That's what that is. It's colder

7 underneath than it is right at the top.

8 And Sugar Creek also has -- because it's

9 deeper you can see more clearly how it

10 stratifies in the summer -- spring and

11 summer.

12 So this fifteen-year data set that

13 I talked about earlier we included the

14 last two years of quarterly profiles in

15 that longer term data set just to

16 validate what we were seeing the last few

17 years in the way of pump back and mixing

18 and this graph shows that the last two

19 years of study data are -- they are

20 consistent with the longer term

21 characteristics, mixing characteristics

22 of Lake Oconee. Again, the

23 stratification tries to set up the

24 springtime. This is just for -- all

25 these graphs are seasonal depictions of


Page 31

1 FERC MEETING

2 what's happening just at the location in

3 front of Wallace Dam.

4 Springtime the stratification

5 begins to set up. You see that by mid

6 summer pump back mixing makes the mixes

7 the water column. The warmest

8 temperatures are mixing, and by fall

9 temperatures are going down and dissolved

10 oxygen concentrations are going back up,

11 and it's certainly affected by pump back

12 mixing, but this is also what we expect

13 to see in the fall when the lake changes

14 and mixes naturally.

15 Overall, as I mentioned before, the

16 water chemistry indicated there's good

17 conditions in Lake Oconee. The results

18 were very similar between both years, and

19 really compared to our whole long-term

20 data set there's not much change in water

21 quality in Oconee. It's been relatively

22 good the whole time. The data set does

23 collect the input of nutrients. A little

24 bit elevated nutrients, particularly

25 phosphorous in the upper end of the


Page 32

1 FERC MEETING

2 reservoir, our main influence. We have

3 had point source discharges. There's a

4 lot of agricultural land uses around

5 Oconee that influence its conditions and

6 its productivity, which, again, is

7 measured -- each productivity is measured

8 as a TSI or a Trophic State Index. A

9 trophic state index is a standardized

10 measure to relay information about

11 productivity of a lake. Typically the --

12 an index is calculated based on

13 concentrations of chlorophyll A or

14 phosphorous or even just water

15 transparency. This means second the

16 water transparency, and the mean of those

17 over time can give you an idea of the

18 trend of condition, at least productivity

19 of the lake.

20 So it falls in this mesotrophic

21 range, but what does that mean? If the

22 lake were to be -- in the extremes, if

23 the lake were to be oligotrophic, it

24 means it's undernourished. Very clear

25 waters, an unproductive fishery, and not


Page 33

1 FERC MEETING

2 many aquatic plants and on the other end

3 of the extreme if a lake is determined to

4 be eutrophic, it's really getting a lot

5 of nutrients.

6 As a matter of fact, not just a lot

7 of nutrients. Excess nutrients that

8 create undesirable water quality

9 conditions and lead to nuisance growths

10 of aquatic plants often and fishery is --

11 is abundant to say the least, and offers

12 really a lot of challenges in managing a

13 fishery in a eutrophic setting. In the

14 long-term TSI speaks to the aging of

15 lakes, and lakes age over hundreds or

16 thousands of the years, depending on the

17 lake and the TSI gives a point in time

18 about the condition of the lake.

19 So Oconee is good. This is good

20 news for Oconee. It remains in a

21 mesotrophic condition. The nutrients --

22 nutrients and Lake Oconee are of interest

23 to not only us for lake condition but

24 also to our agencies and not just EPD,

25 Georgia EPD but EPA. For years now EPA


Page 34

1 FERC MEETING

2 has been rolling out an initiative to

3 try -- they recognized that as

4 development and demographics grow

5 nationwide, including in our Georgia

6 lakes, there are more pressures on the

7 lake, more runoff with nutrients,

8 difficulty controlling the discharges

9 that come from, you know, our regulated

10 discharge points, and so to help preserve

11 long-term condition in our nation's water

12 ways, they propose nutrient criteria or

13 limits on the amount of phosphorous that

14 they want to see in our lakes, and

15 Georgia EPD has adopted those -- that

16 same idea and working with EPA to -- to

17 try to regulate nutrients, and so this

18 next slide speaks a little bit to that.

19 Criteria had been developed by EPD,

20 Georgia EPD for Lake Oconee. In fact, we

21 went out here at Rock Eagle just last

22 week where there were talking more about

23 their intended plan to set the nutrient

24 criteria and chlorophyll A limits also

25 for Lake Oconee. And just to put a note


Page 35

1 FERC MEETING

2 on that, Lake Oconee -- admittedly so,

3 EPD is about five years behind in

4 implementing this plan to set nutrient

5 criteria for Georgia lakes.

6 Oconee is a head of the stack and

7 they are going to continue to do that for

8 all of our Georgia lakes.

9 So that second bullet is about

10 that, and these standards are about

11 limiting nutrient enrichment to help

12 preserve our water quality going forward.

13 The chlorophyll limits are going to be

14 numerical limits for chlorophyll A

15 concentration are proposed, and they'll

16 be measured at three different place in

17 Lake Oconee. EPD has modeled the lake

18 and the inputs, and there are -- it's

19 sensitive enough to detect changes in

20 different parts of our watershed, which

21 is why they are proposing three different

22 monitoring points for chlorophyll A and

23 also for phosphorous, in particular --

24 nitrogen and phosphorus is drivers for

25 nutrient enrichment, they are proposing


Page 36

1 FERC MEETING

2 numerical limits for those as well. It's

3 a good thing for all of our waterways if

4 we're giving this kind can of attention

5 and -- for all of our lakes, and if you

6 want to learn more about this

7 specifically, you know, contact EPD or

8 our regional EPA, and there's lots of

9 information about what's going on now

10 with nutrient criteria, and real quickly

11 a summary about everything we just

12 covered. The monitoring in the tailrace,

13 the continuous monitoring really had the

14 same patterns the second year that they

15 did the first year. The DO impressions

16 that we saw in the tailrace that were

17 below four occurred during May, June,

18 July and August. So we -- actually, the

19 period in the second year was slightly

20 extended as compared to the first year.

21 The pump back operations and I

22 mentioned photosynthesis we believe is a

23 driver and aids to that recovery of DO

24 after the generation cycles and usually

25 to the concentrations that are above the


Page 37

1 FERC MEETING

2 criteria in the 4.0 criteria.

3 The seasonal quarter profiles show

4 similar trends, including and sort of

5 highlighting the mixing effect of the

6 pump back operations, especially in the

7 summer, and the water chemistry overall

8 is good and indicating that Lake Oconee's

9 condition is still steady on a weekly

10 trophic range, and it did pick up or

11 detect these -- still look like elevated

12 nutrient levels upstream.

13 And that is my last slide. We're

14 at a point -- with our whole team here,

15 we'd be glad to answer any questions that

16 we can about the water resources

17 presentation. If you have questions,

18 carry those over to lunch or carry them

19 to the afternoon and then just round me

20 up or Courtney and we'll be glad to help

21 answer any questions that may be

22 afterthoughts.

23 So thank you.

24 MS. O'MARA: Okay. Y'all Steve

25 introduced himself a little bit earlier.


Page 38

1 FERC MEETING

2 He is our consultant who works very

3 closely with us on preparing all our

4 documents and heading up studies and

5 stuff, and he is going to take us through

6 the aeration desktop study that we did,

7 and I'm so excited that they set up

8 because there's coffee in the break.

9 So do you want to take a quick

10 coffee break to get coffee. Why don't we

11 do that. Five minutes.

12 (Brief pause.)

13 MS. O'MARA: This is Steve Layman.

14 He's actually Dr. Steve Layman. He's

15 going to take us through our aeration

16 methods study that we did this past

17 summer.

18 So with that, I'm going to turn it

19 over to Steve.

20 MR. LAYMAN: Thank you. Okay. The

21 title of this study was Aeration Methods

22 to Enhance Summer Dissolved Oxygen in the

23 Wallace Dam Tailrace Area.

24 Georgia Power filed a study plan to

25 investigate aeration methods in February


Page 39

1 FERC MEETING

2 of 2017, and that was done in response to

3 some comments from the Georgia Department

4 of Natural Resources Wildlife Resources

5 Division, and understanding the results

6 of the first season's study, that was

7 approved by FERC in March of 2017. So

8 this study has been conducted over the

9 course of 2017, and the specific

10 objectives of the study were to identify

11 and evaluate using the data collected

12 during the first year of study

13 technically feasible and cost-effective

14 aeration methods for increasing summer

15 dissolved oxygen or DEO levels in the

16 Wallace Dam tailrace area, and as Tony

17 spoke to you about this morning, the

18 tailrace monitoring in the first season

19 of monitoring in 2015, 2016 found a

20 generation correlated with DO going below

21 4 milligrams per liter, and that pattern

22 was replicated again this past summer

23 with DO following below four for portions

24 between May and August.

25 So the study consisted of an


Page 40

1 FERC MEETING

2 aeration methods assessment to

3 characterize a model of withdrawal zone

4 at the turbine intake. So the withdrawal

5 zone in Lake Oconee just upstream from

6 Wallace Dam, which we refer to as the

7 forebay. It also screened a flow age

8 variation alternatives for technical

9 feasibility and efficacy or effectiveness

10 to enhance DO. It modeled turbine

11 aeration to assess the potential for

12 turbine venting or the addition of forced

13 air in the turbines themselves, and it

14 also looked at an in-lake approach for

15 enhancing dissolved oxygen, a conceptual

16 level of design.

17 In addition, Georgia Power

18 conducted a site visit this summer to two

19 different in-lake oxygen diffuser systems

20 that are operated by the Corps of

21 Engineers on the Savannah River. So to

22 get a firsthand look at one of these

23 particular methods.

24 The aeration assessment portion of

25 the study was performed by a team of


Page 41

1 FERC MEETING

2 highly experienced water quality

3 specialist, Jim Ruane from Reservoir

4 Environmental Management, Mark Mobley of

5 Mobley Engineering and Paul Wolff of

6 WolffWare Limited, and all three of these

7 guys worked together and collaborate

8 on -- they collaborated on this project,

9 but they are heavily involved in looking

10 at water quality studies on other

11 reservoirs throughout the eastern and

12 whole United states. They have all

13 formerly worked with Tennessee Valley

14 Authority. Their assessment report --

15 their complete report is provided as an

16 appendix to the report that Georgia Power

17 filed. So I'm going to summarize a lot

18 of what they've done for you today.

19 So the study area, much like the

20 water quality monitoring, consisted of

21 Wallace Dam, the lower end of Lake Oconee

22 just upstream from the Dam are or forebay

23 and the Wallace Dam tailrace going

24 downstream to Georgia 16 Highway bridge.

25 That's the downstream extend of project


Page 42

1 FERC MEETING

2 boundary within the water of the upper

3 end of Lake St. Claire.

4 So Ruane, Mobley and Wolff used the

5 following methods. First they reviewed

6 the water quality monitoring data from

7 the first season of monitoring in 2015

8 and 2016 for both of the reservoirs and

9 tailrace, and they looked at available

10 bathymetry data for the lake, you know,

11 the bottom contours, the depth, the

12 profile at the bottom, and they found

13 data like these on the right-hand side,

14 which Tony touched on a little bit. They

15 found these particularly useful for

16 characterizing the withdrawal zone of the

17 lake. So this is the profile of

18 dissolved oxygen and depth in the

19 reservoir or vertical profile over a

20 24-hour period. So each line represents

21 a different hour, and during pump back,

22 the green lines, you see a very straight

23 vertical line. That's the forebay

24 becoming well mixed, top to bottom. It's

25 the same dissolved oxygen, and during


Page 43

1 FERC MEETING

2 generation at the interim period, you see

3 some stratification where you have higher

4 levels of dissolved oxygen at the top

5 than at the bottom, and this kind of data

6 helped them model the withdrawal zone and

7 to predict the DO concentrations that

8 occured in the pen stock at the

9 powerhouse, and pen stock is the pipe

10 that takes water from the lake into the

11 turbines, and so then you would compare

12 the dissolved oxygens predicted in the

13 withdrawal zone with the criteria that

14 applied to the tailrace to define what

15 levels of enhancement you're going to

16 need. So as Tony, mentioned the

17 dissolved oxygen criteria applicable to

18 the tailrace are 5 milligrams per liter

19 on a daily average basis and 4 milligrams

20 per liter instantaneous at all times.

21 They then had took this information

22 understanding the withdrawal zone

23 distribution of the dissolved oxygen, and

24 screened about ten different enhancement

25 methods, aeration methods that are


Page 44

1 FERC MEETING

2 commonly applied in reservoirs or other

3 hydropower projects and there are two of

4 them up there that are shown up here.

5 We'll talk about some others as we go on,

6 but on the left side the most common

7 approach is turbine venting where you

8 admit air passively into the turbine and

9 it mixes with the water and adds

10 dissolved oxygen and releases downstream,

11 and on the left side, it's basically a

12 cross-section of a turbine with colored

13 areas showing different ways to vent air

14 into a turbine depending on its design

15 and what options might be available.

16 On the right side, another example

17 that uses a different method, is a

18 forebay surface water pump, which would

19 use the propellor -- propellor like

20 device to drive water deeper into the

21 lake. So if there's higher dissolved

22 oxygen water at the surface, you drive it

23 deeper in front of the withdrawal zone of

24 the intake as you get more favorable

25 dissolved oxygen water going through the


Page 45

1 FERC MEETING

2 turbine. So those are two of the methods

3 they looked at.

4 I'm foreshadowing the results a

5 little bit because they found that two of

6 them were the most feasible and looked at

7 those in much greater detail. One was

8 the forebay oxygen line diffuser system

9 under the forebay upstream to the dam.

10 So that's an in-lake aeration system, and

11 the other was draft tube aeration using

12 compressed air. So it's similar to

13 that -- that last image I showed you, the

14 turbine cross-section, where you could

15 force air into the turbine.

16 So for the forebay oxygen line

17 diffuser system, they did some modeling.

18 They used a forebay bubble plume model

19 that would help them develop a conceptual

20 design, and the withdrawal zone model was

21 used for -- for the inputs to that model.

22 For the draft tube aeration, using

23 compressed air, they used another model

24 called a discreet bubble model that is

25 set up just to model dissolved oxygen


Page 46

1 FERC MEETING

2 within the turbines, and they used data

3 from 2015 and 2016 monitoring as the

4 input data of dissolved oxygen, and they

5 simulated dissolved oxygen uptake over

6 age operations and water quality

7 conditions to determine how much air flow

8 would be needed to meet a target

9 improvement to meet the DO criteria. And

10 then they compared these two methods in

11 terms of costs, the installation to put

12 in the systems plus the annual cost to

13 operate them, and in addition, Georgia

14 Power considered the practicality of

15 deploying the system and maintaining the

16 type of system, and as part of that, they

17 conducted site visits.

18 So Georgia Power went over and took

19 a close look at in-lake aeration systems

20 used by the Corps of Engineers on the

21 Savannah River, and the two lakes that

22 they looked at systems on were J. Strom

23 Thurmond Lake and Richard B. Russell

24 Lake. They are right in line upstream of

25 Augusta and on the Savannah River, and


Page 47

1 FERC MEETING

2 you can see Lake Oconee is reasonably

3 close by. So these are also very large

4 reservoir systems, similar physiography,

5 similar climate. The Richard B. Russell

6 Lake also operates in a pump back

7 fashion, and their aeration system is an

8 in-lake forebay system at the dam similar

9 to the design that would be done at

10 Wallace, and Strom Thurmond Lake their

11 aeration system is located about 5 miles

12 upstream of the dam, and it's for a

13 different purpose. It's to place oxygen

14 in a portion of the lake with suitable

15 temperature range for Stripe Bass and to

16 help enhance fishery habitat.

17 The site visit was conducted at

18 the -- in August of this year when both

19 systems were operating, and it was led by

20 the fishery's lead and operations

21 personnel at Richard B. Russell dam. So

22 it was a great opportunity to see the

23 system in operation, ask questions,

24 understand the performance, the

25 maintenance issues and so forth that they


Page 48

1 FERC MEETING

2 encountered in operating these each

3 summer at both of those lakes.

4 So let's talk about the results.

5 These two plots on the right show similar

6 data as the vertical profiles that I

7 showed you earlier, the hourly vertical

8 profiles just in a slightly different

9 format. The X axis is timed and of --

10 there's a 24-hour event over the course

11 of a day as operation changes from

12 generation to an interim period where

13 there's not doing anything to pump back,

14 and you think it would go back to the

15 interim period generation and so forth.

16 So it picked up a full day of operation

17 in the summer, and on the Y axis, on the

18 side, you have depth in the lake. So

19 it's another way to give you a vertical

20 profile but on an hourly basis. The plot

21 on the left is water temperature, and the

22 plot on the right is dissolved oxygen,

23 and the colors just indicate, you know,

24 temperatures of that same value or a

25 narrow range. So it's showing you all


Page 49

1 FERC MEETING

2 the reds, the same temperature all the

3 yellow is the same temperature and so

4 forth, and what you see from this is,

5 during pump back, both here and -- both

6 for temperature and DO, it's almost the

7 same color top to bottom, which means

8 it's well mixed top to bottom. During

9 the generation and the interim period,

10 you can see -- you start to see some

11 layering or stratification where your

12 higher dissolved oxygen and warmer

13 temperature are on the top layer, and

14 that gets disrupted and every day, when

15 you get pump back, it gets mixed again.

16 So the prevailing trend -- and Tony

17 touched on this -- is that you get

18 complete vertical mixing of the water

19 model during pump back at night. After

20 that's finished, you start to get some

21 gradual stratification of the water

22 column, and it increases as the

23 generation begins as you start to pull in

24 fresh water from upstream and you have

25 photosynthesis occurring in the daytime.


Page 50

1 FERC MEETING

2 The DO level goes up on the surface, and

3 why is this important? This is just

4 important to understand where the high

5 dissolved oxygen water is in the water

6 column when you're looking at alternative

7 aeration methods.

8 Their modeling of the withdrawal

9 zone of -- upstream of the dam found that

10 the generation flows primarily come from

11 the upper layer of the forebay, even

12 though the center line of the intake is

13 about 70 feet deep. So what that is

14 trying to say is that most of the water

15 that's drawn in when they generate power,

16 most of it is coming from the upper

17 portion of the water column in the lake.

18 The in-take is fairly deep, but it still

19 pulls a lot from the upper end and -- the

20 upper water column, and the reason that

21 is partly the orientation of the dam

22 itself. The red line is a perpendicular

23 line straight out in front of the dam,

24 and you can see it's pulling water from

25 over on that southwest shoreline of the


Page 51

1 FERC MEETING

2 lake. So it's pulling from the shallower

3 zone, in general, and then the V-shape

4 bottom of the lake and just the fact that

5 they are pulling so much water that

6 there's way more water in the upper water

7 than below. So that's the -- the trend

8 is they found is the turbines pulled

9 generally from the upper portion of the

10 lake, and, again, that's important in

11 understanding the kind of aeration

12 options available.

13 Okay. So they screened ten

14 different aeration methods, and I'll show

15 you there's five on each screen here.

16 This is just a quick attempt at

17 summarizing some of the considerations

18 that were involved in the screening and

19 in a simple yes/no whether they have

20 decided whether it's technically feasible

21 or not on the scale needed on Wallace

22 Dam. Some of these might be effective on

23 a small scale, but at the scale needed

24 when you're generating power at 20,000

25 plus CFS, at least, you know, that's a


Page 52

1 FERC MEETING

2 major consideration or major limitation.

3 So the first one, for example,

4 turbine venting, that's the most common

5 approach used in hydroelectric plants

6 across the nation for aerating turbine

7 release, but it's -- they determined it

8 was not feasible because of the pressures

9 in the draft to -- were not negative

10 enough or low enough to create the vacuum

11 needed to pull air passively into the

12 turbines. That wasn't feasible due to

13 the site specific set up of the turbine

14 at Wallace. The second option -- we're

15 going to talk about here in a little more

16 detail the forebay oxygen line diffuser

17 system, and that's a passive system where

18 oxygen bubbles are diffused into the

19 reservoir upstream of the dam, and then

20 that area of the water was discharged

21 during generation to go downstream. That

22 is technically fees able at Wallace.

23 Forebay surface water pumps, those

24 are pumps that would blend high dissolved

25 oxygen water near the surface with water


Page 53

1 FERC MEETING

2 down lower in the water column, but that

3 did really to benefit Wallace Dam because

4 the withdrawal zone already is pulling

5 from the upper portion of the water

6 column and the pump back keeps everything

7 well-mixed anyway.

8 So this is just some examples of

9 the process they went through in

10 evaluating different options.

11 The fourth one: Draft two

12 variation using the compressed air. It's

13 similar to number one above, turbine

14 venting, but it's forcing the air in and

15 using compressors to force air into

16 the -- into the -- below the turbine into

17 the draft to mass technically feasible.

18 So we're going to look at that in more

19 detail.

20 The bottom one is a forebay

21 aeration line diffuser system which

22 sounds a lot like the second one, the

23 forebay oxygen line diffuser system. The

24 difference is that the oxygen one uses

25 pure liquid oxygen as the source.


Page 54

1 FERC MEETING

2 The airline diffusers -- aeration

3 line uses air, and air is only comprised

4 of 20 percent oxygen. So you need a lot

5 more air to go into that system, and,

6 furthermore, you have to compress it and

7 force it in. So it's a bigger system,

8 and it costs a lot more money. It's not

9 as feasible. So it was not done. So I'm

10 not going to go through that level with

11 this next page. They kind of went

12 further down in, I think, applicability

13 and potential. Other various mixing

14 systems, forebay, skimmer devices,

15 multi-level intake structures. I'll stop

16 on one more because this comes out. Tail

17 water aeration structure. Why can't you

18 just put aeration down in the tailrace

19 like constructing a weir or some other

20 structure that's going to aerate the

21 waters that it pass it downstream. Well

22 weirs and things like that involve a

23 change in elevation, water falling and

24 getting aerated, and that's not going to

25 work during pump back. You know, as


Page 55

1 FERC MEETING

2 you've heard, at night, the turbines

3 reverse and the flow is going upstream

4 into the lake, and these -- a lot of

5 these types of measures would obstruct

6 that flow or wouldn't be technically

7 feasible going upstream.

8 Okay. So let's look at the forebay

9 oxygen line diffuser system and what it

10 entails. And so this is a diagram on the

11 right of the -- of a forebay of the lake.

12 I didn't explain this earlier. I thought

13 it looked pretty clear. Here is the dam,

14 here is the lake, the water is going that

15 way downstream. It doesn't show the

16 turbines or the powerhouse.

17 It's just showing simple flow of

18 water. So this one the diffuser line is

19 along the bottom here, and it's placing

20 oxygen down beneath the withdrawal zone

21 and the bubbles move upward in the water

22 column, aerate a large volume of water

23 and then the generation begins. That

24 water is pushed downstream and into the

25 higher dissolved oxygen content.


Page 56

1 FERC MEETING

2 There are about 15 -- at least 15

3 systems like this currently in use in the

4 United States. Many of them are in the

5 southeast. They were innovated at TVA.

6 They have about nine in use. The Corps

7 has two that we mentioned on the Savannah

8 River, and Duke Power has one at the

9 Tillery development that they just began

10 operating a few years ago in North

11 Carolina. These are some other

12 components of the oxygen line diffuser.

13 This is a close up of the diffuser line

14 on the bottom right here, and we're --

15 really what it just shows you is some of

16 the elements that are involved. You have

17 that yellow tube that's -- it's a

18 buoyancy pipe that you can -- it's filled

19 with air or you can fill it with water,

20 and that's used to raise or sink the line

21 to the bottom of the lake as needed. The

22 black line is an oxygen supply line

23 that's coming from your onshore facility,

24 and on this thinner line, it kind of

25 loops, that's the diffuser line. So the


Page 57

1 FERC MEETING

2 oxygen goes into that, the porous hose,

3 and doubles out and moves up into the

4 surface, up into the water column above,

5 and you can see that it's tethered to

6 anchors at the bottom of the lake in this

7 case, and they can be elevated any

8 elevation above the bottom of the lake

9 that's desired depending on the modeling,

10 how you can best optimize oxygen transfer

11 into the water column.

12 This is the conceptual design of a

13 forebay oxygen line diffuser system for

14 Wallace Dam, in particular, that Ruane,

15 Mobley and Wolff developed. This design

16 would have two sets of diffuser lines.

17 So you can see the red lines going up the

18 lake would be the porous hose that would

19 be distributing oxygen in a relatively

20 large area, and there would be two sets

21 of them. There's a longer upstream set

22 and a shorter set near the dam.

23 The upstream set would inject a low

24 level of oxygen continuously to maintain

25 a certain critical mass of dissolved


Page 58

1 FERC MEETING

2 oxygen in the forebay, and then the

3 shorter set of lines just upstream of the

4 dam would be used only during generation

5 to boost the oxygen output right when

6 generation is beginning and the water is

7 going downstream into the tailwater.

8 The maximum oxygen capacity of this

9 system was estimated to be about 200 tons

10 per day of oxygen for the worst case

11 condition. So the worst hottest days of

12 summer when dissolved oxygen drops below

13 four the most that you would need a rate

14 of 200 tons per day, and that doesn't

15 mean much probably for me to say that.

16 It will on the slide when I tell you how

17 often that has to be supplied, but the

18 medium use is about 60 tons per day in

19 the assessment that they did.

20 So here is the cost analysis of the

21 forebay oxygen line diffuser system at

22 Wallace Dam. They estimated a capital

23 cost of about $4.7 million. That

24 includes installing the diffuser lines,

25 the supply lines, liquid oxygen storage


Page 59

1 FERC MEETING

2 and the supply facility. In addition,

3 the estimated annual cost of liquid

4 oxygen would run from -- based on the

5 modeling they did -- I'm sorry -- based

6 on the water quality monitoring in 2015

7 and 2016 would range from about 150 to

8 $24,000 per year. Up to eight or nine

9 tanker trucks would deliver liquid oxygen

10 each week during the high oxygen demand

11 periods. So that might be just a few

12 weeks each summer, but still during those

13 highest peaks, it would require a

14 constant delivery of oxygen to the

15 system.

16 This is a series of photos from the

17 site visit to the J. Strom Thurmond

18 aeration system to give you an idea of

19 the onshore facilities. You can see the

20 liquid oxygen tanks and piping on the

21 left side, and the vaporizer system. So

22 the oxygen is liquid in the tanks. It's

23 released through the piping system and

24 valves to the vaporizer which uses the

25 atmospheric condition to warm it up and


Page 60

1 FERC MEETING

2 convert it to gas, and the pressure in

3 that system pushes it into the diffuser

4 lines, and it's regulated by the oxygen

5 flow control valves.

6 This is a biologist's explanation.

7 I'm sure an engineer could do much

8 better.

9 Okay. Let's shift gears and look

10 at the draft tube aeration using

11 compressed air, and what would be

12 involved with it. This is an active

13 design that would use compressors or

14 blowers to force air into the draft tube

15 immediately blowing the turbine unit. So

16 the turbine is sitting there. Use the

17 prime tube that comes out of the

18 tailwater and you can see just kind of

19 the flow of oxygen as it's released

20 through that system.

21 The pressure and the time of water

22 passage would allow for acceptable gas

23 transfer. That was part of their

24 analysis that you could transfer

25 sufficient dissolved oxygen to -- to


Page 61

1 FERC MEETING

2 achieve the DO targets, but there are

3 potential implications to this system in

4 terms of loss of unit efficiency from the

5 power that's used to operate the blowers

6 and the compressors and excessive total

7 dissolved gases, which we'll refer to as

8 TDG, Total Dissolved Gases. Not just

9 oxygen but nitrogen, and the releases can

10 be a concern, and I'll touch on that in a

11 moment.

12 So their conceptual design for

13 Wallace they modeled it using the

14 discreet bubble model that was based on

15 the geometry of the draft tube and to

16 simulate the gas transfer that would

17 occur through that system. So the model

18 predicted air flows that would be

19 required to achieve dissolved oxygen on a

20 daily average of 5 milligrams per liter,

21 as well as the resulting total dissolved

22 gas levels, TDG levels, and they made

23 assumptions to moderate energy losses and

24 moderate levels of total dissolved gas in

25 their effort, and through this modeling,


Page 62

1 FERC MEETING

2 they estimated the sizes and numbers of

3 compressors that would be required and

4 the piping and the electrical work, all

5 that's needed to come up with a cost

6 estimate, as well.

7 The plots on the bottom show you

8 the types of output that their model

9 produced. So on the left side, it's days

10 along the bottom. So it's like during

11 the summer how much flow is occurring

12 through the units. Those are the blue

13 vertical lines, and then how much

14 dissolved oxygen is needed to bring it up

15 to the target level, and then that was

16 used to determine how much air flow would

17 be needed through the compressor to

18 achieve that.

19 So the right-hand graph shows the

20 same dates in the summer and then the

21 levels of air flow that would need to be

22 pumped into there to achieve those

23 improvements.

24 They also looked at total dissolved

25 gas, and that's something that has to be


Page 63

1 FERC MEETING

2 measured in the water which, we didn't

3 have the benefit of having measurements

4 of total dissolved gas in the tailrace.

5 As I mentioned, you know, if you mix air

6 with water with compressed air, you're

7 not only getting dissolved oxygen.

8 You're getting dissolved nitrogen, and

9 maybe small amounts of dissolved methane

10 and other minor components, but you're

11 increasing all the gases and turbine

12 releases can become super saturated with

13 gas, even without thought adding

14 additional air. Apparently below

15 downstream of dams you can have total

16 dissolved gas exceeding the saturation by

17 5 to 25 percent.

18 So this wasn't measured, but they

19 made some assumptions, and they bracketed

20 a range of background total dissolved

21 nitrogen in the water, and then they

22 predicted in the modeling if you add all

23 this compressed air to achieve the DO

24 performance what would the total

25 dissolved gas be in the discharge, and so


Page 64

1 FERC MEETING

2 there are three scenarios represented

3 here by the blue, red and purple lines

4 and total dissolved gas percent

5 saturation on the left side. This is an

6 exceedance plot. So it says what

7 proportion of the time and certain level

8 of total dissolved gas would be exceeded.

9 So let's say you pick 110 percent

10 saturation, which is starting to get into

11 a level of concern for aquatic bio tay in

12 terms of dissolved gas. So 110 percent

13 at this medium level -- here is

14 110 percent. So about 45 percent of the

15 time in that scenario the total dissolved

16 gas would be above 110 percent

17 saturation. If you went to their most

18 extreme assumption on their bracketed

19 range, it would always be above

20 110 percent in that instance. So while

21 they might have site-specific data and

22 they made some reasonable assumptions, if

23 Georgia Power had selected this method

24 and wanted to move forward, they would

25 probably be advised to study that in more


Page 65

1 FERC MEETING

2 detail.

3 So here is the cost analysis of

4 draft two variation using compressed air.

5 The estimated capital cost is

6 $15.2 million, and that assumes two

7 blowers per turbine including some quotes

8 from your equipment manufacturers and p

9 sizing based on evaluation of the

10 historical DO data, and there's some

11 elements that it doesn't include like

12 piping design and some of the more site

13 specific information, but it's still

14 substantially higher than the in-lake

15 forebay oxygen line diffuser system. The

16 losses due to generation on annual basis

17 are estimated about $140,000 per year.

18 As I mentioned, the other concerns for

19 compressed -- using the compressed air

20 would be the potential issues with total

21 dissolved gas, noise of the blowers,

22 maintenance and that type of thing.

23 So we're winding down here to the

24 conclusion of the assessment by Ruane,

25 Mobley and Wolff. A forebay oxygen line


Page 66

1 FERC MEETING

2 diffuser system is the most technically

3 feasible and cost effective approach for

4 enhancing some review of concentrations

5 in the Wallace dam tail trace.

6 The benefits of this system of

7 compressed air would be that the

8 installation costs are $10 million less.

9 There are no obligations to the

10 powerhouse and turbines. There would be

11 no impacts to unit efficiency or

12 operations, and it would avoid total

13 dissolved gas concerns in turbine

14 releases.

15 So, in summary, ten aeration

16 approaches were reviewed and evaluated

17 for there technical feasibility and

18 efficacy for reducing summer DO at

19 Wallace Dam. We looked at conceptual

20 designs and installation costs for a

21 forebay oxygen line diffuser system and

22 draft tube aeration using compressed air.

23 A site visit was conducted, which

24 provided valuable incite into the

25 practical callet of the system deployment


Page 67

1 FERC MEETING

2 and the study conclude that the forebay

3 oxygen line diffuser system would be the

4 most tangibly feasible and cost-effective

5 and practical approach, and with that,

6 I'll open the floor to questions, and

7 then Courtney and Greg can add?

8 MS. FOSTER: What happens if you

9 don't do anything? I mean, we just saw

10 this presentation that the dissolved

11 oxygen looked good?

12 MR. LAYMAN: Well, if we don't do

13 anything, it would continue to operate

14 the same way it does now, and so you

15 would have summers -- in the summertime

16 you would get the dissolved oxygen

17 dropping below the numeric criteria that

18 the state has as a requirement for

19 achieving water quality standards.

20 So that's the implication -- one

21 implication. A primary one to consider

22 is it still wouldn't be meeting that

23 water quality criteria.

24 Anybody?

25 MS. O'MARA: I realize -- so now


Page 68

1 FERC MEETING

2 that we've looked at the study results

3 for our second season of studies, I

4 realized -- thank you, Steve -- that I

5 got too gung ho and I skipped over just a

6 few of the slides, and I just have one in

7 particular I want to go back to and it

8 takes us back to where we are in the

9 schedule. So if you can hang on, I'm

10 going to pull up our timeline, and I

11 still think we'll meet our lunchtime.

12 So remember I said we're about

13 three years into this five-year -- we're

14 about three and a half years in.

15 So I just want to -- this is not

16 really an important slide, but -- well,

17 it is because it's FERC's timeline for

18 the integrated licensing process.

19 So the top part is the blue, and

20 that's what we've been doing. We've been

21 meeting. We've been filing reports. So

22 we have two more bubbles that we're

23 hitting. This is -- the red circled one

24 is what we're doing today. We'll file

25 our licensing proposal and then license


Page 69

1 FERC MEETING

2 application. Those are the two major

3 deadlines, and then all of the green

4 things are what FERC is doing, and there

5 is actually some deadlines for some of

6 our agencies within that green time

7 frame, as well, but what I really just

8 sort of want to take you to was to this

9 next slide to take you back to the main

10 schedule that we have for the overall

11 project.

12 So we filed our progress reports on

13 the second season's studies in -- at the

14 end of August, and then last week we

15 filed, on October 11th, the final study

16 reports, and that's for the second season

17 reports. Remember, we had a first season

18 where we filed final study reports for

19 those at the end of last year. So

20 October 17, that's today. We're here.

21 Your next deadline -- well, actually it's

22 my deadline -- is November 10th. I'm

23 going to file a meeting summary of this

24 meeting. So that's why we have the court

25 reporter. I include the sign-in sheets.


Page 70

1 FERC MEETING

2 So if you haven't signed your name on the

3 sign-in sheet, please do so when you go

4 to lunch. We'll include who was here.

5 We'll include copies of our slides, and I

6 think we did a separate summary, too,

7 just an overall -- we'll include the

8 agenda, that type of thing. So all of

9 that goes into the FERC record, and you

10 can get any document off of the FERC's

11 electronic library. You just use the

12 project number for Wallace, which is at

13 the top of your agenda. It's P-2413-117.

14 So especially for anybody that

15 wants more detail behind the studies, the

16 studies are already up there on the

17 electronic library. You just need to

18 pull them up. They were filed

19 October 11th. So I'll file the November

20 10th study results meeting summary. Then

21 December 11th is y'all's chance to file

22 something, and it's if you disagree with

23 the meeting or maybe anything that we've

24 said in the summary if you recall it

25 differently, and then January 9th we get


Page 71

1 FERC MEETING

2 a chance to respond to your comments if

3 there are any, and then in February 8th

4 FERC resolves the disagreements because

5 they are here.

6 So this is one part of the master

7 timeline. There's sort of a parallel

8 path that goes on at the same time for

9 the preliminary licensing proposal, which

10 is what we're doing after lunch.

11 So we'll have a separate table for

12 this that deals with just the preliminary

13 licensing proposal.

14 So after lunch we're going to

15 present to y'all what we are proposing

16 today for this next license. This is

17 what we would send up to FERC, and FERC

18 is going to take everyone's comments and

19 balance, and then we would we get a

20 license at the end of it that is a

21 balance of what everyone wants

22 essentially.

23 So, anyway, this is just the second

24 season study comment timeline. So that's

25 all I wanted to say.


Page 72

1 FERC MEETING

2 Lunch is supposed to be ready at

3 11:30.

4 Does anyone have any comments or

5 questions about any of this first part?

6 Okay. So I'm going to basically

7 adjourn the updated study results

8 meetings, and then our lunch will be

9 held, if you walk up -- if you go out one

10 of these back doors, which is open, just

11 walk up the steps. The building right

12 behind us is the new cafeteria. You go

13 right in that side door. Go to the

14 right. We have a private room. This is

15 where we've been eating before. Just

16 hang a right once you get in that

17 building.

18 Okay. That's it. Thank you.

19

20 (Thereupon, the meeting was

21 concluded at approximately 11:15 a.m.)

22

23

24

25


Page 73

1

2 C E R T I F I C A T E

3

4 STATE OF GEORGIA:

5 FULTON COUNTY:

6

7 I hereby certify that the foregoing

8 deposition was reported, as stated in the

9 caption, and the questions and answers

10 thereto were reduced to written page

11 under my direction, that the preceding

12 pages represent a true and correct

13 transcript of the evidence given by said

14 witness.

15 I further certify that I am not of

16 kin or counsel to the parties in the

17 case, am not in the regular employ of

18 counsel for any of said parties, nor am I

19 in any way financially interested in the

20 result of said case.

21 Dated this 20th day of October,

22 2017.

23

24 _______________________________

Tanya L. Verhoven-Page,

25 Certified Court Reporter,

Wallace Dam Relicensing Study Results ... - Georgia Power · Along with this cover letter, this...

Documents

Transcript of Wallace Dam Relicensing Study Results ... - Georgia Power · Along with this cover letter, this...