r. brown, ee&t, inc. d. cornwell, ee&t, inc. m. …...• disturbances during lslr have been...

R. Brown, EE&T, Inc.

D. Cornwell, EE&T, Inc.

M. Schmelling, DC Water

11

• Funding

– WRF 4584 TC = DC Water & WRF

• Participating Utilities

– Four water systems

• PI

– David Cornwell

• WRF PM

– Jonathan Cuppett

• PAC

– A. Putz, M. Freidman, N. Charlton, M. Corson

22

• Disturbances during LSLR have been shown to increase particulate and total lead in weeks/months following replacement

• Can in-home, high velocity flushing eliminate or mitigate these impacts?

– Flush by opening all taps inside the house for several minutes to dislodge and remove particulate lead from premise plumbing and from the service line after replacement

• Can this same type of flushing help other high lead households (e.g., with or without LSLR)

33

• Traditional “flushing” - displacement

– Performed to displace old stagnant water

– Not necessarily for particulate removal

• High velocity “flushing” - dislodgement

– Analogous to “unidirectional” flushing of dist. sys.

– Objective is to dislodge, and then remove particulate material from pipes, fittings, and other parts of plumbing

– In this case to remove all loose particulate material between household taps and water main

44

• Dislodge particulate lead

– that may otherwise be subsequently released to customer

• Mobilize and remove

– Remove aerators and screen

– Run long enough duration and high enough rate to dislodge particles and move them to tap

– Water from tap goes to drain (i.e., lead is not in pipes any more)

55

• Many unidirectional flushing programs used in the distribution system target 6 to 8 ft/s.

– We often find success is possible at velocities near

2.5 ft/s; however, it requires longer flush duration.

• Examples

– ¾-in pipe at 3.5 gpm (9.5 L/min)

• velocity of about 2.5 ft/s (0.78 m/s)

– 1-in pipe at 10 gpm (~38 L/min) - typical this study

• ~4 ft/s (1.2 m/s)

• 30 min duration for this study

66

• Flush - use one of three types after PLSLR

Flush hose bibs - outside the house (SL only) – group “A”

Same as “A” but longer duration = group “B”

Whole-house flush (by customer) = group “C”

• Findings

Little improvement with 2 methods of flush for LSL only (outside the house)

Improvement by 1st mo after whole-house flush (customer)

7

99

0.0-0.5 L4.3-4.8 L

8.6-9.1 L0.0010

0.0100

0.1000

A01 A02 A03 A04 B01 B02 C01 C02 C03 C04

Pb

Co

ncen

tra

tio

n (

mg

/L) 0.0-0.5 L

4.3-4.8 L

8.6-9.1 L

1010

0.0-0.5 L4.3-4.8 L

8.6-9.1 L0.001

0.01

0.1

A01 A02 A03 A04 B01 B02 C01 C02 C03 C04

Pb

Co

ncen

trati

on

(m

g/L

)

0.0-0.5 L

4.3-4.8 L

8.6-9.1 L

1111

0.0-0.5 L4.3-4.8 L

8.6-9.1 L0.001

0.01

0.1

A01 A02 A03 A04 B01 B02 C01 C02 C03 C04

Pb

Co

ncen

trati

on

(m

g/L

)

0.0-0.5 L

4.3-4.8 L

8.6-9.1 L

• One-time Flush 30 min, at least one tap per floor, aerator off, highest rate (esp. bathtubs)

• Collect 12 or more consecutive 1L samples

– Aerator off

– After 6 hr stagnation

– “normal” flow rate (see next slide)

• Analyze total & dissolved Pb, Mn, and Cu

– Some utilities analyzed other metals too (e.g., Fe)

• Sequence

– Most locations = Sample, flush, collect 1 day later, then monthly intervals thereafter

– Eight locations = sample, PLSLR, flush, collect 1 day later, monthly intervals thereafter

1212

This presentation will focus on total Pb

• Rates at all locations were consistent with normal water use

– Worked out to be about 25s to fill a 1L bottle, or 2.4 L/min

• Locations at PWS 2 followed the normal velocity samples with “high rate” samples

– These were about 4 to 6s per L, or 15 to 10 L/min

1313

1414

Table 2.1

Participating utilities

PWS 2 PWS 6 PWS 4 PWS 3

Lead control strategy

pH and alkalinity adjustment yes

Pb(IV) yes

Orthophosphate yes yes yes

Residual disinfectant

Free Chlorine yes yes

Chloramines yes yes

Water chemistry

Entry point pH 7.2 8.5 7.2 7.6

Alkalinity (mg/L as CaCO3) 66 75 13 100

Free chlorine residual (mg/L as Cl2) >1 0.6

Combined residual (mg/L as Cl2) 2.7 1.7

PO4 residual (mg/L as P) 0.8 0.7 0.6

Sample collection

Sample collection by B A A B

A = customers in their own homes (mostly were staff homes or homes of relatives)

B = trained PWS staff at customer homes

• Impact of flush w/ vs w/o aerator removed

16

0

10

20

30

40

50

60

1 2 3 4 5 6 7 8 9 10 11 12

To

tal L

ea

d (

µg

/L)

Profile Volume (L)

Location XM - PLSLR and household flush w/ aerator on 07/08/2015, 2nd whole house flush aerator off 07/13/2015

pre-LSLR (06/23) post-LSLR & flush w/ aerator on (07/09)

post-flush w/ aerator off (07/14) later post-flush (07/30)

below DL

one 07/09/2015 value not shown7th L, 199 µg/L

17

• normal flow = no improvement high rate = improvement

18

0.1

1

10

100

10001 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

H1

H2

H3

H4

H5

H6

H7

H8

H9

H10

H11

H12

H13

H14

H15

H16

H17

H18

H19

H20

To

tal L

ea

d (

µg

/L)

Profile Volume (L)

Location MT (Flush and PLSR 04/2015)

initial 1 day 1 mo 2 mo 3 mo 4 mo

Household plumbing: no leadSL: 4.0 - 13.6 L (before PLSLR)

4.0 - 16.7 L (after PLSLR)LSL: 4.0 - 13.6 L (before PLSLR)

4.0 - 10.5 L (after PLSLR)

19

Normal sampling velocity High sampling velocity

• improvement between 1st and 2nd month

– Especially in first 11 L (inside house till end of SL)

20

0.1

1

10

100

10001 2 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

20

H1

H2

H3

H4

H5

H6

H7

H8

H9

H1

0

H1

1

H1

2

H1

3

H1

4

H1

5

H1

6

H1

7

H1

8

H1

9

H2

0

To

tal L

ea

d (

µg

/L)

Profile Volume (L)

Location TN (Flush and PLSR 05/2015)

initial 1 day 1 mo 2 mo 3 mo 4 mo

Household plumbing: unknown materialSL: 5 - 9.9 L (before PLSLR)

5 - 11 L (after PLSLR)LSL: 5 - 9.9 L (before PLSLR)

5 - 6.5 L (after PLSLR)

21

• Little improvement in “normal” velocity samples, much greater improvement in high velocity samples

– Household through SL

23

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7 8 9 10 11 12 H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 H11 H12

To

tal L

ea

d (

µg

/L)

Profile Volume (L)

Location HX (Flush no PLSR 10/2014)

initial 1 mo 2 mo

Household plumbing: no leadSL: 2.7 - 8.3 L All SL is unknown material

24

0

5

10

15

20

25

30

35

40

45

50

To

tal L

ea

d (

µg

/L)

Profile Volume (L)

Location TH (Flush no PLSR 02/2015)

initial 1 mo 2 mo

Household plumbing: some leadSL: 4.3 - 8.8 LLSL: 4.3 - 8.8 L

25

• improvement in 1st mo return to pre-flush by 2nd mo.

26

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 H11 H12

To

tal L

ea

d (µ

g/L

)

Profile Volume (L)

Location KQ (Flush no PLSR 08/2014)

initial 1 mo 2 mo

Household plumbing: some leadSL: 4.1 - 9.0 L

4.1 - 7.35 L is unknown materialLSL: none

27

• Lead levels increase after flushing

– but no samples after 2nd month

28

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

To

tal L

ea

d (µ

g/L

)

Profile Volume (L)

Location KS (Flush no PLSR 05/2014)

initial 1 mo 2 mo service line LSL

Household plumbing: no lead

29

• Slightly worse during first 2 mo, improvement thereafter

– Improvement continues up to 16 mo after single flush event

30

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10 11 12

To

tal L

ea

d (µ

g/L

)

Profile Volume (L)

Location HA (Flush 07/2014)

initial 1 day 1 mo 2 mo 3 mo 4 mo 7th mo 16th mo service line LSL

31

• Lead levels decrease after flushing

– Lower levels maintained up to at least 10 mo

– Some higher Pb on 1st day

32

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

To

tal L

ea

d (

µg

/L)

Profile Volume (L)

Location AW (Flush July 27, 2014)

initial 1 day 1 mo 2 mo 10 mo service line LSL

3333

3535

• Peak Total Lead

• Difference relative to pre-flush

–Positive = increase

–Negative = decrease

-40

-20

0

20

40

60

80

HM MT TN TT XM XF XO XA HX KQ KS KX OG QJ TH AW QA AE AK HA HJ

Diffe

ren

ce

in

Pe

ak L

ea

d V

ers

us P

re-f

lush

(µ

g/L

)

Location

Difference after in-home flush = 1 day ("+" means pre-flush higher, "-" means post-flush higher)

flush - no PLSLR

+228 µg/L

-191 µg/L

PLSLR w/ flush

-40

-20

0

20

40

60

80


Diffe

ren

ce

in

Pe

ak L

ea

d V

ers

us P

re-f

lush

(µ

g/L

)

Location

Difference after in-home flush = 1 month("+" means pre-flush higher, "-" means post-flush higher)

+170 µg/L

-277 µg/L

flush - no PLSLRPLSLR w/ flush

-40

-20

0

20

40

60

80


Diffe

ren

ce

in

Pe

ak L

ea

d V

ers

us P

re-f

lush

(µ

g/L

)

Location

Difference after in-home flush = 2 months("+" means pre-flush higher, "-" means post-flush higher)

+1,964 µg/L

-320 µg/L

- 41 µg/L


-40

-20

0

20

40

60

80


Diffe

ren

ce

in

Pe

ak L

ea

d V

ers

us P

re-f

lush

(µ

g/L

)

Location


-316 µg/L

- 61 µg/L


-40

-20

0

20

40

60

80


Diffe

ren

ce

in

Pe

ak L

ea

d V

ers

us P

re-f

lush

(µ

g/L

)

Location


-320 µg/L

- 68 µg/L


-40

-20

0

20

40

60

80


Diffe

ren

ce

in

Pe

ak L

ea

d V

ers

us P

re-f

lush

(µ

g/L

)

Location

Difference after in-home flush = >6 months ("+" means pre-flush higher, "-" means post-flush higher)


4343

• Add total lead in all 12 samples for 1st L + 2nd L + 3rd L + etc. (normal rate)

Each date

Each location

<DL = 0

• With and without PLSLR

0.1

1

10

100

1000

10000

0.1 1 10 100 1000 10000

Po

st-

Flu

sh

Cu

mu

lati

ve T

ota

l L

ead

(µ

g)

Pre-Flush Cumulative Total Lead (µg)

PLSLR, then flush

1 day 1 mo 2 mo 3 mo 4 mo

0.1

1

10

100

1000

10000

0.1 1 10 100 1000 10000

Po

st-

Flu

sh

Cu

mu

lati

ve T

ota

l L

ead

(µ

g)

Pre-Flush Cumulative Total Lead (µg)

Flush, no PLSLR

1 day 1 mo 2 mo 3 mo 4 mo 6 mo or more

• High velocity flushing after PLSLR

– PLSLR already known to disturb lead for a few months• PWS provides instructions for water use in the 1st few months after PLSLR

– Flushing appears to make it better during this period (i.e., ~2 mo instead of longer w/o flushing)

– Some data shows immediate improvement after whole house flush but other times it takes longer (~2 months)

• High velocity flushing without PLSLR

– increased disturbance may cause higher lead in 1st couple of months

– Lead levels come down in subsequent months

• Both

– Data suggest higher velocity, longer flush, and/or repeat flush events may be needed

4646

4747

• Lead scale analysis

• Lead isotopes (source/fate tracking)

48

• EE&T Further Pioneering Analysis:

– XRD-crystalline Structures

– XRF and Raman-amorphous structures

– SEM/EDS-elemental analysis

– Pb Isotope Analysis for source and fate tracking

37

Shows Turbicule Cross-section

Richard Brown

[email protected]

712 Gum Rock CourtNewport News, Virginia 23606(757) 873-1534 (757) 873-2392 – Faxwww.eetinc.com

52

r. brown, ee&t, inc. d. cornwell, ee&t, inc. m. …...• disturbances during lslr have been...

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