2015 IWA Specialist Group

on Lake and Reservoir

Management Tour

Paul Gantzer, Ph.D., P.E.

Mark Mobley, P.E.

Carvins Cove

Spring Hollow Falling Creek

Parameter

Surface Area 0.61 km2

(150 acres) 2.5 km2

(1100 acres) 0.28 km2

(69 acres) 0.12 km2

(29 acres)

Volume 120,000 Ml (3200 x 106 gal) 231,000 Ml (6200 x 106 gal) 1700 Ml (430 x 106 gal) 310 Ml (90 x 106 gal)

Max Depth 62 m (200 ft) 23 m (70 ft) 15 m (50 ft) 9.3 m (30 ft)

Production 30 MLD (8 MGD) 114 MLD (30 MGD) X X 7.5 MLD (2 MGD)

Spring Hollow Carvins Cove Beaver Dam Falling Creek

Western Virginia Water Authority

Spring Hollow Water Treatment Plant

1.

1. Clarification/Filtration

2.

2. GAC/Fluoridation

3.

3. Chemical Storage

4. Backwash Decant Tanks

4. 4.

5.

5. Clearwell

Reservoir (O2 & ClO2

added)

Spring Hollow Water Treatment Unit

Upflow

Clarifiers Gravity

Filters

Carvins Cove

Water Treatment Plant

1. Aerators

2. Coagulation

3. Flocculation

4. Sedimentation

5. Filtration

6. Disinfection

2 3 4

5

6

1

Pre-Treatment (ClO2)

Hypolimnetic

Oxygenation

Falling Creek Water Treatment Plant

Aeration Flocculation

Tube Settlers

Filtration

Coagulant

Addition

Crystal Spring Water Treatment Plant

• 5 units (1.2 MGD each)

• 102 modules per unit

• Microfiltration

• Chlorine and Fluoride addition post filtration

• Spring source – 3.5 MGD consistently

1

2

4

5

6

3

7 8

1 2

4 3

6 5

7

8

Background

SHR

3408

CCR

2440

0

1000

2000

3000

4000

Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

Pro

file

s C

oll

ecte

d _

1996 Bob Benninger

Roanoke County Utility Department (RCUD)

Mark Mobley

Tennessee Valley Authority (TVA) John Little

Virginia Tech (VT)

Conference Beer

1997 • Spring Hollow Reservoir

• 3000 ft line diffuser

• Two 75 Hp Ingersol Rand air compressor

• SCFM ?

1997 (Aeration)

1998

X

• Spring Hollow Reservoir

• John Little

• SCUBA gear

• One 2” HDPE Ball Valve (~180’)

• 1500 ft line diffuser

• Two 75 Hp Ingersol Rand air compressor

• SCFM ?

1998 (Aeration)

1999 • Spring Hollow Reservoir

• 1500 ft line diffuser

• Two 75 Hp Ingersol Rand air compressor

• SCFM ?

1999 (Aeration) 10

5

15

20

25

35

30

Station

10 20 30 35 25 15 5 20 & 25

Aver

age

Sta

tion D

iffe

rence

-2

-1

0

1

2

2000 • Spring Hollow Reservoir

• Professor on Sabbatical

• $1000

2000 (Aeration)

375

380

385

390

395

400

405

410

0 5 10 15 20

Dissolved Oxygen (mg/L) Temperature (C)

Ele

vati

on (

m)

YSI Data

Profiles

Hydrolab Data

Profiles

Baseline O2 demand

(initial)

(-0.05 g/m3day)

3 days O2 accumulation

(0.40 g/m3day)

Remainder O2 accumulation

(0.13 g/m3day)

1 week following oxygenation

(-0.14 g/m3day)

Baseline O2

demand (final)

(-0.05 g/m3day)

2.00

3.00

4.00

5.00

6.00

7.00

8.00

13-Jul 12-Aug 11-Sep 11-Oct 10-Nov

Time (Days)

Dis

solv

ed O

xyge

n (g

/m3)

Diffuser Induced O2 Demand

0.27 and 0.09 g/m3day

2000 (Aeration) Induced Oxygen Demand

2001 • Spring Hollow Reservoir

• No pumping

• No Aeration

2001 Background DO Demand

370

380

390

400

410

420

Ele

vation (

m)

200 220 240 260 280 300 320 340

Julian Day (2001)

370

375

380

385

390

395

400

405

410

415

420

425

0.0

1.0

2.0

3.0

4.0

5.0

6.0

8.0

10.0

12.0

14.0

16.0

1996

2001

2002

June

July

Augu

st

Septe

mber

Octo

ber

2002 • Spring Hollow Reservoir

• Replace 2” floater w/3”

• Orifice in “T”

• Upgrade to LOx

2002

Line diffuser

upgrades

2003 (LOx vs Air)

Air

8.45 mg/l

9.24 mg/l

4400 kg

15 days

48 Nm3 h-1

(28 SCFM)

O2

8.32 mg/l

12.60 mg/l

6300 kg

12 days

14 Nm3 h-1

(8 SCFM)

Gas

Start DO

Final DO

DO add

Duration

Flow

Flow

2003 Data Collection

(Spring Hollow)

Seabird Electronics SBE 19Plus

High Resolution Profiler (CTD)

2003 (Spring Hollow Data)

368

372

376

380

384

388

Ele

vation (

m)

165 175 185 195 205 215 225 235 245

Distance (m)

165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240 245

368

370

372

374

376

378

380

382

384

386

388

390

0.0

1.0

2.0

3.0

4.0

5.0

Idealized Plume Modeled Plume

8-Jun 28-Jun 18-Jul 7-Aug 27-Aug 16-Sep 6-Oct 26-Oct 15-Nov

Date

2003 SHR DO Profiles

365

375

385

395

405

415

425

435

0 2 4 6 8 10 12 14 16 18 20

DO Concentration (mg l -1

)

Ele

va

tio

n (

m)

Background (Pre-Air)

Aeration Initial

Aeration Final

Background (Pre-O2)

Oxygenation Initial

Oxygenation Final

2003 Oxygen Flux Hypothesis

L2

2D =

Hypolimnion Temperature

Air O

N

Air O

FF

O2 O

N

O2 O

FF

4.0

4.5

5.0

5.5

6.0

6.5

7.0

19-May 8-Jun 28-Jun 18-Jul 7-Aug 27-Aug 16-Sep 6-Oct 26-Oct

Date

Tem

per

atu

re (

C)

0.008 C d-1

0.073 C d-1

0.007 C d-1

0.020 C d-1

0.004 C d-1

2003 (Induced Mixing Hypothesis)

Averaged Hypolimnion Concentration

8.0

9.0

10.0

11.0

12.0

13.0

8-Jun 28-Jun 18-Jul 7-Aug 27-Aug 16-Sep 6-Oct 26-Oct 15-Nov

Date

Dis

solv

ed O

xygen

Con

cen

trati

on

(m

g/l

)

Aeration (Observed) Post Aeration Oxygenation (Observed)

Post Oxygenation Air Added Oxygen Added

0.20 mg l-1

d-1

0.06 mg l-1

d-1

-0.04 mg l-1

d-1

0.37 mg l-1

d-1

0.36 mg l-1

d-1

-0.05 mg l-1

d-1

2003 IOD and Applied Gas Flow Rate

2004 Carvins Cove

Oxygenation Design

• Background

– (~435 kg d-1)

• Plant Withdrawal

– (275 – 510 kg d-1)

• DIOD

– 3.8 x Background

• Metals

– ~100 kg d-1

• Total O2 Demand

~2100 kg d-1

2005 • Carvins Cove Reservoir

• 4000 ft line diffuser (2 x 2000 ft)

• 9000 gallon LOx tank

• 40 SCFM

2005 Carvins

Cove

HOS install

2005 (Oxygenation) Carvins Cove 2005 DO Profiles (July 31 - November 3)

Diffuser Operational / Water Column Stratified

1090

1100

1110

1120

1130

1140

1150

1160

1170

0 1 2 3 4 5 6 7 8 9 10

DO (mg/l)

Ele

vati

on

(ft

)

31-Jul

1-Aug

8-Aug

15-Aug

25-Aug

29-Aug

5-Sep

12-Sep

22-Sep

6-Oct

13-Oct

20-Oct

27-Oct

3-Nov

2006 • Carvins Cove Reservoir

• 4000 ft line diffuser (2 x 2000 ft)

• 9000 gallon LOx tank

• 40 SCFM

• Test water column response to

oxygenation

2006 (Carvins Cove Oxygenation)

335

337

339

341

343

345

Ele

vation (

m)

Ele

va

tio

n (

m)

30 40 50 60 70 80 90 100 110 120

Distance (m)

7.2

7.4

7.6

7.8

8.0

8.2

8.4

2.0

3.0

4.0

5.0

6.0

7.0

DMPR

ED

Diffuser ADiffuser B

June 6, 2006

2006

(Carvins Cove

Oxygenation)

June 1, 2006 (Increased flow 15 to 40 SCFM)

x

x x

x

x

x

x

2006 Carvins Cove Diffuser Operation (Off / On)

Diffuser Off

Diffuser On

0

0.2

0.4

0.6

0.8

1

1-Jun 22-Jun 13-Jul 3-Aug 24-Aug

Date (2006)

Man

gan

ese

Co

nce

ntr

atio

n, M

n (

mg

l -1)

_

344.4 m (1130 ft) 341.4 m (1120 ft) 338.3 m (1110 ft)

2006

335

338

341

344

347

351

354

Ele

vation (

m)

1100

1110

1120

1130

1140

1150

1160

Ele

vation (

ft)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov

Date (2006)

344.4 m

341.1 m

338.3 m

2007 (Oxygenation) HODmass and Applied Gas Flow Rate

SHR 2003 - 2007

CCR 2005 - 2007

SHR

y = 6x + 50

R2 = 0.9

CCR

y = 22x + 420

R2 = 0.9

0

500

1000

1500

2000

2500

3000

3500

0 20 40 60 80 100 120

Oxygen Flow Rate (NCMH)

HO

Dm

ass

(k

g d

ay -1

) _

2007 O2 Penetration

into Sediment (CCR)

adapted from Bryant et al. 2011

2007 Carvins Cover Manganese Overview

0.0

0.4

0.8

1-Apr 1-Jun 1-Aug 1-Oct 1-Dec 1-Feb 3-Apr 3-Jun 3-Aug 4-Oct 4-Dec

Date (2006-2007)

_

0

40

80

_

1.0

2.0

3.0

4.0

5.0

6.0

Man

gan

ese

(mg

l -1

)_

0

20

40

60

80

100

120

Flo

w R

ate

(NC

MH

) _

2008 - 2010

Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07

36529 36712 36895 37078 37261 37444 37627 37810 37993 38176 38359 38542 38725 38908 39091 39274

336

340

344

348

352

356

Ele

vation (

m)

0.0

0.1

0.3

0.4

0.5

1.0

1.5

2.0

2.5

3.0

Off (Jun 15, 06)

On(Jul 12, 06)

Diffuser InstalledAug 1, 05

Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07

336

340

344

348

352

356

Ele

vation (

m)

36600 36800 37000 37200 37400 37600 37800 38000 38200 38400 38600 38800 39000 39200 39400 0.0

0.1

0.5

1.0

2.0

3.0

4.0Off (Jun 15, 06)

On(Jul 12, 06)

Diffuser InstalledAug 1, 05

Iron Manganese

2008 - 2010

Operational

Impact on Mn

755 kg/day

917 kg/day

830 kg/day

975 kg/day

1126 kg/day

0

2,000,000

4,000,000

6,000,000

8,000,000

10,000,000

12,000,000

2004 2005 2006 2007 2008 2009 2010

Year

Oxygen

Del

iver

ed (

SC

F)

_

$2,246 Avg

$47,171 Total

$1,912 Avg

$55,434 Total

$2,134 Avg

$64,029 Total

$2,482 Avg

$52,116 Total

$3,067 Avg

$42,932 Total

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11

Mn C

once

ntr

atio

n (

mg l -1

)

_

1140 1130 1120 1110

0

0.5

1

1.5

2

2.5

3

3.5

Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11 Jan-12

Date

Man

gan

ese,

Mn (

mg l -1

) _

Bottom Total Mn Bottom Soluble Mn Hypolimnion Total Mn Hypolimnion Soluble Mn

Gantzer Water Resources Engineering, LLC

Re-oxygenate Continuous

2008 – 2010

Spring Hollow

O2 depletion rate

over time

2011 Falling Creek

Hybrid Design

Problems:

• Algae

• Mn, Fe, PO4

• Hypolimnetic Anoxia

• Detritus / Metalimnetic minimum

Solutions:

• Deeper epilimnion

• Raise DO > 5 mg/l

• Hypolimnetic Oxygenation

• Zone aerate/oxygenate

170 200 230 260 290 320 3501200

1220

1240

1260

1280

1300

1320

1340

1360

2001

Algae

50 80 110 140 170 200 230 260 290 320

1200

1220

1240

1260

1280

1300

1320

1340

1360

1997

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.0

15.0

Detritus

Anoxia

Withdrawal

Elevations

2011 Falling Creek Hybrid Design Destrat

SS

Depth (m) Elevation (m) Elevation (ft) cum MG % Total Volume

0.1 506.9 1663.0

0.4 506.6 1662.0 81.6

0.7 506.3 1661.0 72.3 0.89

1.0 506.0 1660.0 63.6 0.78

1.3 505.7 1659.0 55.7 0.68

1.6 505.4 1658.0 48.4 0.59

1.9 505.1 1657.0 41.9 0.51

2.3 504.7 1656.0 36.1 0.44

2.6 504.4 1655.0 30.9 0.38

2.9 504.1 1654.0 26.5 0.32

3.2 503.8 1653.0 22.7 0.28

3.5 503.5 1652.0 19.5 0.24

3.8 503.2 1651.0 16.8 0.21

4.1 502.9 1650.0 14.4 0.18

4.4 502.6 1649.0 12.2 0.15

4.7 502.3 1648.0 10.2 0.13

5.0 502.0 1647.0 8.5 0.10

5.3 501.7 1646.0 7.1 0.09

5.6 501.4 1645.0 5.8 0.07

5.9 501.1 1644.0 4.7 0.06

6.2 500.8 1643.0 3.8 0.05

6.5 500.5 1642.0 3.0 0.04

6.8 500.2 1641.0 2.3 0.03

7.1 499.9 1640.0 1.7 0.02

7.4 499.6 1639.0 1.2 0.01

7.7 499.3 1638.0 0.8 0.01

8.0 499.0 1637.0 0.4 0.01

8.3 498.7 1636.0 0.2 0.00

8.7 498.3 1635.0 0.1 0.00

9.0 498.0 1634.0 0.0 0.00

9.3 497.7 1633.0 0.0 0.00

Destratify

Oxygenate

Transition

90%

1 (10)%

2012 Falling

Creek Install /

Testing

Buoyancy

Lines

• Pump Inlet

• Oxygenation out

• Destrat

• Conduit (fiber optics)

1. Conduit

2. Chemical Feed

3. Destrat

1 2

3

Saturation

chamber Destrat

(Air supply)

PSA

(O2 supply) Pump

controller

2012 Falling Creek Oxygenation

(SSS)

• Submersible pump

w/ VFD (60 GPM/50 psi)

• Saturation chamber

• O2 supply (PSA)*

• Uniform discharge

header (250 ft)

• 32 SCFH (.53 SCFM)

• 65 psia 90% Purity

• 25 kg/d (Background DO demand 5 kg/d)

*

Centrox

2012 Falling Creek Diffused Air Mixing, aka VEMmer (+ Chemical Feed)

• Dual elevation (5 meter

or 1.5’ above bottom)

• 750 ft long with 90ft

ON/OFF sections

• Chemical feed 9 GPM

• One (1 GPM) nozzle per destrat section

497

499

501

503

505

507

0.0 5.0 10.0 15.0 20.0 25.0 30.0

Temperature (deg C) and DO (mg/l)

Ele

vati

on

(m

) _

497

499

501

503

505

507

-25 -20 -15 -10 -5 0 5 10 15 20 25

Plume Width (m)

Ele

vati

on

(m

) _

Temp_C DO_mg/l TPLUME COMG B ED DMPR

Gantzer Water Resources Engineering, LLC

DT 2 ºC 12 SCFM

~95 MGD 18 Hours

KAESER: SX-7.5 SIGMA Profile Rotary Screw Air

Compressor 28 cfm @ 125 psig

Station

10 20 30 35 25 15 5 20 & 25

Av

erag

e S

tati

on

Dif

fere

nce

-2

-1

0

1

2

Baseline O2 demand

(initial)

(-0.05 g/m3day)

3 days O2 accumulation

(0.40 g/m3day)

Remainder O2 accumulation

(0.13 g/m3day)

1 week following oxygenation

(-0.14 g/m3day)

Baseline O2

demand (final)

(-0.05 g/m3day)

2.00

3.00

4.00

5.00

6.00

7.00

8.00

13-Jul 12-Aug 11-Sep 11-Oct 10-Nov

Time (Days)

Dis

solv

ed O

xyge

n (g

/m3)

Diffuser Induced O2 Demand

0.27 and 0.09 g/m3day

370

380

390

400

410

420

Ele

vation (

m)

200 220 240 260 280 300 320 340

Julian Day (2001)

370

375

380

385

390

395

400

405

410

415

420

425

0.0

1.0

2.0

3.0

4.0

5.0

6.0

8.0

10.0

12.0

14.0

16.0

2003 SHR DO Profiles

365

375

385

395

405

415

425

435

0 2 4 6 8 10 12 14 16 18 20

DO Concentration (mg l -1

)

Ele

va

tio

n (

m)

Background (Pre-Air)

Aeration Initial

Aeration Final

Background (Pre-O2)

Oxygenation Initial

Oxygenation Final

330

335

340

345

350

355

360

6.0 11.0 16.0 21.0 26.0 31.0Temperature (C)

Ele

vat

ion (

m)

_

330

335

340

345

350

355

360

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Dissolved Oxygen (mg l -1

)

Ele

vat

ion (

m)

_

31-Jul 1-Aug 8-Aug 15-Aug 29-Aug 5-Sep 22-Sep 13-Oct 3-Nov

336

340

344

348

352

Ele

vation (

m)

0 200 400 600 800 1000 1200 1400 1600 1800

Distance (m)

Carvins Cove Reservoir June 6, 2006

Withdrawal Elevation

344.4

347.5

DMPR

ED

Diffuser-B

Diffuser-A

Horizontal Spreading

Diffuser Off

Diffuser On

0

0.2

0.4

0.6

0.8

1

1-Jun 22-Jun 13-Jul 3-Aug 24-Aug

Date (2006)

Man

gan

ese

Co

nce

ntr

atio

n, M

n (

mg

l -1)

_

344.4 m (1130 ft) 341.4 m (1120 ft) 338.3 m (1110 ft)

2013 -

Pre

sen

t