Car

ollo

Tem

plat

eWat

erW

ave.

pptx

Optimizing Slime Control Chemical Feed in Tarrant

Regional Water Districts Raw Water PipelinesP. Greg Pope Ph.D., P.E.

Rob Cullwell P.E.

Jason Gehrig P.E. (TRWD)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

3

TRWD Raw Water Supply System

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

4

Why feed chloramines?

Bio-Film Control

Zebra Mussel Mitigation

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

5

Key Project Goals

• Richland Chambers and Cedar Creek– Improve chloramine feed efficiency– Protect intake conduit/towers– Improvements to existing chemical systems

• Benbrook – Design new chloramine feed system

• Sampling program to monitor chloramine decay• Quantify impacts of biofilm on pipeline friction

factor and power use

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

6

Key Project Goals

• Richland Chambers and Cedar Creek– Improve chloramine feed efficiency– Protect intake conduit/towers– Improvements to existing chemical systems

• Benbrook – Design new chloramine feed system

• Sampling program to monitor chloramine decay• Quantify impacts of biofilm on pipeline friction

factor and power use

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

7

Bench-Scale Testing

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

8

Region 1Monochloramine

Formation

Region 2Monochloramine

Destruction

Region 3Free Chlorine

Residual

Tota

l Chl

orin

e &

Free

Am

mon

iaC

once

ntra

tions

More Chlorine AddedChlorine to Nitrogen (Cl2:N) Mass (Molar) Ratio

0 3 (0.6) 5 (1) 7.6 (1.5)

Breakpoint

Free Ammonia

Total Chlorine

DW

Proper Cl2/N ratio critical for chloramine stability

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

9

Higher Cl2/N ratios increased chloramine decay

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 20 40 60 80 100

Mon

ochl

oram

ine

(mg/

L as C

l 2)

Time from sample collection (hours)

Cedar Creek pH 8.1

Richland Chambers pH 8.1

Benbrook pH 7.9

Notes:1) Water Source: Cedar Creek, Richland Chambers, Benbrook2) Date: 12/15/20143) Cl2:N ratio: 4.5:1 4) Simultaneous addition of chlorine and ammonia

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

10

Higher Cl2/N ratio increases chloramine decay

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 20 40 60 80 100

Mon

ochl

oram

ine

(mg/

L as C

l 2)

Time from sample collection (hours)

Cedar Creek pH 7.6

Richland Chambers pH 8.1

Benbrook pH 7.9

Notes:1) Water Source: Cedar Creek, Richland Chambers, Benbrook2) Date: 12/15/20143) pH:ambient4) Cl2:N ratio: 5.5:1 (solid symbols); 4.5:1 (open symbols) 5) Simultaneous addition of chlorine and ammonia

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

11

High Cl2/N ratio increases DBP formation

0

2

4

6

8

10

12

Cedar Creek Richland Chambers Benbrook

TTHM

Form

ation

(µg/

L)

4.5:1

5.5:1

Notes:1) 48 hour incubation2) pH ambient3) TOC: Cedar Creek = 5.8 mg/L; Richland

Chambers = 4.5 mg/L; Benbrook = 4.7 mg/L

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

12

High Cl2/N ratio increases DBP formation

0

2

4

6

8

10

12

Cedar Creek Richland Chambers Benbrook

HAA5

Form

ation

(µg/

L)

4.5:1

5.5:1

Notes:1) 48 hour incubation2) pH ambient3) TOC: Cedar Creek = 5.8 mg/L; Richland

Chambers = 4.5 mg/L; Benbrook = 4.7 mg/L

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

13

Proper pH critical for chloramine stability100

80

60

40

20Tota

l Com

bine

d C

hlor

ine

(%)

pH3 5 6 7 8

Trichloramine

Monochloramine

Dichloramine

Normal Range

9

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

14

pH variability in source waters

5.0

6.0

7.0

8.0

9.0

10.0

11.0

8/11/1987 5/7/1990 1/31/1993 10/28/1995 7/24/1998 4/19/2001 1/14/2004 10/10/2006

pH

Date

RC (0.5m) CC (0.5m)*Note: Data from Jan 1990 to Mar 2008

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

15

pH variability in source waters

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0

Perc

ent n

ot Ex

ceed

ing (

%)

pH

RC (0.5m) CC (0.5m)*Note: Data from Jan 1990 to Mar 2008

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

16

Higher pH decreases chloramine decay: Cedar Creek

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 5 10 15 20 25 30 35 40 45

Tota

l Chl

orin

e, M

onoc

hlor

amin

e Re

sidu

al (m

g/L)

Time (hours)

pH 7.0 Total ChlorinepH 7.0 MonochloraminepH 8.3 Total ChlorinepH 8.3 Monochloramine

Notes:1) Water Source: Cedar Creek2) Date: 8/26/20143) Cl2:N ratio: 4.5:14) Chloramine Dose: 5.0 mg/L5) Simultaneous addition of chlorine and ammonia

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

17

Higher pH decreases chloramine decay: Richland Chambers

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 5 10 15 20 25 30 35 40 45

Tota

l Chl

orin

e, M

onoc

hlor

amin

e Re

sidu

al (m

g/L)

Time (hours)

pH 7.0 Total ChlorinepH 7.0 MonochloraminepH 8.3 Total ChlorinepH 8.3 Monochloramine

Notes:1) Water Source: Richland Chambers2) Date: 8/26/20143) Cl2:N ratio: 4.5:14) Chloramine Dose: 3.5 mg/L5) Simultaneous addition of chlorine and ammonia

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

18

Full-Scale Testing

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

19

Pipeline Sampling Locations

Waxahachie Pump Station

Richland-ChambersLake Pump

Station

Cedar CreekLake Pump

Station

Ennis Pump Station

Blackjack Road

Rosewood Ranch

NE 1036

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

20

Chloramine Decay in the Pipeline: Cedar Creek

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 5 10 15 20 25

Tota

l Chl

orin

e, M

onoc

hlor

amin

e Re

sidu

al (m

g/L)

Time (hours)

Total Cl2 (hold)

NH2Cl (hold)

Total Cl2 (pipeline)

NH2Cl (pipeline)

Lake Pumpstation

Waxahachie

Rosewood Ranch

Ennis Pumpstation

Blackjack Road

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

21

Chloramine Decay in the Pipeline: Richland Chambers

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 5 10 15 20 25

Tota

l Chl

orin

e, M

onoc

hlor

amin

e Re

sidu

al (m

g/L)

Time (hours)

Total Cl2 (hold)

NH2Cl (hold)

Total Cl2 (pipeline)

NH2Cl (pipeline)

Lake Pumpstation

Waxahachie

NE 1036

Ennis Pumpstation

Blackjack Road

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

22

Chloramine loss from nitrification

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

23

Chloramine loss from nitrification

Monitoring Parameters:• Monochloramine• Free ammonia• Nitrite• Nitrate

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

24

Nitrification parameters measured in the pipeline: Cedar Creek

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0

0.5

1

1.5

2

2.5

3

3.5

4

PS RR Ennis BJ Wax

Cedar Creek

NH3

/Nitr

ite a

s N (m

g/L)

Tota

l Chl

orin

e/M

onoc

hlor

amin

e (m

g/L)

Total Cl (mg/L) Mono Chl (mg/L) NH3 (mg/L) Nitrite (mg/L)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

25

Nitrification parameters measured in the pipeline: Richland Chambers

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0

0.5

1

1.5

2

2.5

3

PS NE 1036 Ennis BJ Wax

Richland Chambers

NH3

/Nitr

ite a

s N (m

g/L)

Tota

l Chl

orin

e/M

onoc

hlor

amin

e (m

g/L)

Total Cl (mg/L) Mono Chl (mg/L) NH3 (mg/L) Nitrite (mg/L)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

26

Additional Pipeline Sampling Locations

Waxahachie Pump Station

Richland-ChambersLake Pump

Station

Cedar CreekLake Pump

Station

Mansfield

Kennedale Balancing Reservoir

Arlington Outlet

Midlothian

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

27

Additional pipeline sampling: Cedar Creek

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

0

0.5

1

1.5

2

2.5

3

3.5

Pump Station

Waxahachie Midlothian Mansfield @ Church

KBR Arlington Outlet

NH3

/Nitr

ite/N

itrat

e as

N (m

g/L)

Tota

l Chl

orin

e/M

onoc

hlor

amin

e (m

g/L)

Total Chlorine Monochloramine Free Ammonia Nitrite Nitrate

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

28

Additional pipeline sampling: Richland Chambers

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0

0.5

1

1.5

2

2.5

3

Pump Station

Waxahachie Midlothian Mansfield @ Church

KBR Arlington Outlet

NH3

/Nitr

ite/N

itrat

e as

N (m

g/L)

Tota

l Chl

orin

e/M

onoc

hlor

amin

e (m

g/L)

Total Chlorine Monochloramine Free Ammonia Nitrite Nitrate

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

29

Chloramine Decay in the Pipeline: Richland Chambers – August 2015

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 10 20 30 40 50

Tota

l Chl

orin

e Re

sidu

al (m

g/L)

Time (hours)

8/15 (hold)

8/15 (pipeline)Lake Pumpstation

Waxahachie

Ennis Pumpstation

Rosewood Ranch

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

30

Chloramine Decay in the Pipeline: Richland Chambers – August 2015

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 10 20 30 40 50

Tota

l Chl

orin

e Re

sidu

al (m

g/L)

Time (hours)

8/15 (hold)

8/15 (pipeline)

9/11 (pipeline)

9/15 (pipeline)

Lake Pumpstation

Waxahachie

Ennis Pumpstation

Rosewood Ranch

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

31

Test for Presence of Nitrifying Bacteria

0.2 micron filter

Pipeline water sample

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

32

Nitrification evaluation in the Cedar Creek pipeline: Blackjack Road

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6 7 8 9

Nitr

ite/F

ree A

mm

onia

(mg/

L as N

)

Mon

ochl

oram

ine

(mg/

L as C

l 2)

Time from sample collection (days)

NH2Cl (mg/L)

NH3 (mg/L)

Nitrite (mg/L)

Notes:1) Dashed lines represent filtered sample (0.2 µm filter)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

33

Nitrification evaluation in the Cedar Creek pipeline: Blackjack Road

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6 7 8 9

Nitr

ite/F

ree A

mm

onia

(mg/

L as N

)

Mon

ochl

oram

ine

(mg/

L as C

l 2)

Time from sample collection (days)

Monochloramine (mg/L)Monochloramine (mg/L)NH3 (mg/L)Nitrite (mg/L)NH3 (mg/L)Nitrite (mg/L)

Notes:1) Dashed lines represent filtered sample (0.2 µm filter)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

34

Nitrification evaluation in the Richland Chambers pipeline: Blackjack Road

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 1 2 3 4 5 6 7 8 9

Nitr

ite/F

ree A

mm

onia

(mg/

L as N

)

Mon

ochl

oram

ine

(mg/

L as C

l 2)

Time from sample collection (days)

NH2Cl (mg/L) NH3 (mg/L)

Nitrite (mg/L)

Notes:1) Dashed lines represent filtered sample (0.2 µm filter)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

35

Nitrification evaluation in the Richland Chambers pipeline: Blackjack Road

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0 1 2 3 4 5 6 7 8 9

Nitr

ite/F

ree A

mm

onia

(mg/

L as N

)

Mon

ochl

oram

ine

(mg/

L as C

l 2)

Time from sample collection (days)

Monochloramine (mg/L)Monochloramine (mg/L)NH3 (mg/L)Nitrite (mg/L)NH3 (mg/L)Nitrite (mg/L)

Notes:1) Dashed lines represent filtered sample (0.2 µm filter)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

36

Nitrification Control

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

37

Nitrification Control

Nitrification Control → Inactivation > Growth

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

38

Nitrification Control

Nitrification Control → Inactivation > GrowthOperational Controls• Chloramine Concentration

• Free ammonia concentration

• Residence time (reaction time)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

39

Nitrification Control

Nitrification Control → Inactivation > GrowthOperational Controls• Chloramine Concentration

• Free ammonia concentration

• Residence time (reaction time)

• Free Chlorination of Pipeline

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

40

Conclusions

• Optimum chloramine formation conditions lead to – Reduced decay– Reduced DBP formation

• Significant nitrification occurring in the pipeline– Increased chloramine loss

• Demonstrated simple test for the presence of nitrifying bacteria

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

41

Next Steps…..

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

42

Contact Information

P. Greg Pope, Ph.D., P.E.Carollo Engineersgpope@carollo.com512.453.5383

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

43

Extra Slides

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

44

TTHM Formation

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35

TTHM

(µg/

L)

Time (minutes)

Cedar Creek

Richland Chambers

Benbrook

Notes:1) Samples collected 9/4/20142) pH: Cedar Creek - 7.5

Richland Chambers - 7.8Benbrook - 8.1

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

45

Historical LSI – Raw Water

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

Perc

ent n

ot Ex

ceed

ing (

%)

LSI

Cedar Creek Reservoir Richland Chambers Reservoir Benbrook Reservoir

Notes: 1) Data from Jan 1990 to Mar 2008 (depth

ranges from 3-6m)2) Data obtained from Appendix A of Water

Quality Analysis Technical Memorandum (RPS Espey)

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

46

Caustic currently fed to Cedar Creek for Corrosion control

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-1.500 -1.000 -0.500 0.000 0.500 1.000 1.500

Perc

ent n

ot Ex

ceed

ing (

%)

LSI

Cedar Creek Intake Cedar Creek Treated

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

47

DBP formation testing

0

2

4

6

8

10

12

14

16

18

20

Waxahachie (10 hours)

Lake Pump Station Hold (22 hours)

Bench (22 hours)

Waxahachie (13 hours)

Lake Pump Station Hold (22 hours)

Bench (22 hours)

TTHM

(µg/

L); H

AA5

(µg/

L); N

DMA

(ng/

L)TTHM

HAA5

NDMA

Total Chlorine Demand

Notes:1) Samples collected 9/4/20142) Bench testing - Chlorine and ammonia added

simultaneously at a 4.5:1 Cl2:N ratio3) NDMA detection limit = 2 ng/L

Richland Chambers Cedar Creek

Car

ollo

Tem

plat

eWat

erW

ave.

pptx

48

High Cl2/N ratio increases DBP formation

0

2

4

6

8

10

12

14

Cedar Creek Richland Chambers Benbrook

NDM

A Fo

rmati

on (n

g/L)

4.5:1

5.5:1

Notes:1) 48 hour incubation2) pH ambient3) TOC: Cedar Creek = 5.8 mg/L; Richland

Chambers = 4.5 mg/L; Benbrook = 4.7 mg/L