2/20/2014

1

WATER QUALITY UPDATE

February 20, 2014

Presented by:Amy Blain, Project Manager

Melinda Friedman, Confluence Engineering Group, LLC

Outline

► Emergency Waterline Replacement

► Customer Outreach

► Distribution System Water Quality Progress Report

► Pipe Rigs

► Time of Travel Study

► Phosphates

► White Spotting Investigation

► Recommendations

2/20/2014

2

► New mains and all customer services are complete

► Existing alley mains disconnected from Baltimore main January 30th

► Baltimore main abandoned between 15th and 20th Avenues

► Hydrant installation is underway; minimal disturbance expected

► Pavement repairs 50% complete on Beech; restoration work continues

► Final completion delayed to late March due to inclement weather

► Improved water quality and chlorine residual in new mains

Progress Report – Emergency Water Mains

Alley Main Between 16th and 17th Avenues

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Iron, C

hlorine (mg/L)

Free Chlorine Total Iron Secondary MCL ‐ Iron

Main Replacement

2/20/2014

3

Baltimore Area Water Quality (600 Block)

0

1

2

3

4

5

6

7

1/15/2014 1/22/2014 1/29/2014 2/5/2014 2/12/2014 2/19/2014

Total Iron (mg/L)

Sample Date

15th Ave 17th Ave 18th Ave 19th Ave SMCL

Disconnected from Baltimore Main

Progress Report – Customer Outreach

► Ongoing bottled water delivery

Discontinued Dec. 31, 2013 for customers served by new alley main

► Customer complaints down to 5 - 6 per week

► Rate reductions approved for 372 customers

6-month reductions expire April, 2014

Original 2-month reductions expired Feb. 9, 2014

3 new rate reductions approved since Jan. 23, 2014

► YMCA shower privileges – Unaware of any use over last 2 months

► News from the Well updates published regularly

2/20/2014

4

Progress Report - Distribution System Water Quality

► Ongoing distribution system sampling at 9 sites

Acceptable chlorine level at all areas except Site 17 – but improving in this area

Oxidation Reduction Potential (ORP) stabilized at all areas except Site 17 – but improving in this area

Mn level routinely at or below SMCL at all areas

Recent trends show fluctuations in iron and manganese, but this is due to lower chlorine and absence of flushing due to weather concerns

Test results indicate the distribution system can be stabilized

Chlorine Residual Trends

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Free

 Chlorine (m

g/L)

POE Site 14 Site 15 Site 16

Site 17 Site 18 Site 5 Site 22

Site 23 Recommended Minimum

2/20/2014

5

Soluble Manganese Trends

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Soluble M

anganese (m

g/L)

POE Site 14 Site 15 Site 16 Site 17 Site 18 Site 5 Site 22 Site 23 Secondary MCL

Total Iron Trends

0

0.5

1

1.5

2

2.5

3

3.5

4

Total Iron (mg/L)

POE Site 14 Site 15 Site 16 Site 17 Site 18 Site 5 Site 22 Site 23 Secondary MCL

2/20/2014

6

Apparent Color Trends

0

15

30

45

60

75

90

105

120

135

150

165

180

195

210

225

240Apparen

t Color (color units)

POE Site 14 Site 15 Site 16 Site 17

Site 18 Site 5 Site 22 Site 23 Secondary MCL

Progress Report - Pipe Rig Studies

► What is a pipe rig?

Small-scale distribution system used to study and understand the full-scale system

Assembled from existing pipes recently removed from the system

• Alley between 16th and 17th

• Ocean Beach Hwy

Water flows through the pipes, like in the real system

Different flow rates and stagnation times can be studied

Alternate chemical treatments could be evaluated

2/20/2014

7

Pipe Rigs

Water Quality Degradation with Increasing Stagnation Time

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 3 6 15 24

Total M

anganese (mg/L)

Free Chlorine Residual  and 

Total Iron (mg/L)

Stagnation Time (Hrs)

Free Chlorine

Total Iron

Total Manganese

2/20/2014

8

Water Quality Recovery following 15-hr Stagnation

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0 2 4 6 8 10 12

Total M

anganese (mg/L)

Free Chlorine Residual and

Total Iron (mg/L)

Time After Flow Re‐Started (Hours)

Free Chlorine

Total Iron

Total Manganese

Pipe Rig Studies - Findings

► Chlorine residual (and ORP) dropped significantly, especially with more than 6-hours of stagnation

► High levels of iron and manganese were observed, due to loss of chlorine residual and ORP

► Water quality rapidly improved along with chlorine residual and ORP when freshly treated water flows through the pipe rig

► Results can be used to develop proactive guidelines for maintaining water quality throughout distribution system

Iron and manganese are controlled when chlorine ≥ 0.6 mg/L

2/20/2014

9

Average Chlorine vs. Iron for On-going Distribution System Sites

R² = 0.8878

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

Total Iron (mg/L)

Tot Cl2 (mg/L)

SMCL

R² = 0.4402

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

Tot Mn (mg/L)

Tot Cl2 (mg/L)

Average Chlorine vs. Manganese for On-going Distribution System Sites

SMCL

2/20/2014

10

Manganese Release Controlled when Chlorine ≥ 0.6 mg/L - Area around 600 Block

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.2 0.4 0.6 0.8 1

Total M

n(m

g/L)

Chlorine (mg/L)

Causes of Chlorine Demand (Chlorine Loss)

Bulk Water

Pipe Wall

Total Chlorine Demand

~ 0.4 mg/L

> 1 mg/L

2/20/2014

11

Travel Time vs. Chlorine at Water Quality Locations

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0

10

20

30

40

50

60

Free Cl2(m

g/l)

Time(hrs)

Elapsed Time (hrs) CL2

Fluoride Tracer StudyJanuary-2014

DAY-1 PROGRESSION DAY-2 PROGRESSION DAY-3 PROGRESSION

Time of Travel Map

2/20/2014

12

Progress Report - Phosphate Treatment Option

► Evaluations: Jar tests to evaluate polyphosphate ability to reduce discoloration due to

soluble iron and manganese

Tile spotting tests to assess impacts on white spotting

► Findings: Moderately effective at sequestering soluble iron, minimally effective for

manganese

• Polyphosphates decay over time

• Tracer study determined travel times

Did not visually reduce white spotting

Did not change solid phases

► Recommendations: Do not proceed with full-scale implementation at this time

• Unless it proves impossible to maintain chlorine residuals throughout system using other means

White Spotting Reduction Investigations

► What is causing the white spotting?

Hardness?

Silica?

Other evaporative solids?

► Used tile spotting tests to evaluate several treatment approaches

Phosphates? (Not effective)

Softening (Calcium and magnesium removal)

Silica removal

2/20/2014

13

Softening/Silica Removal Bench Studies

► Compared spotting potential associated with different softening techniques

Ion exchange

Pellet softening

Lime softening

► Very little, if any, visual improvement observed with softening alone

► Visible improvement observed with 50% silica reduction

► Greatest improvement with 75% silica reduction

Example Tile Spotting Results

Current Point of Entry Water 100% Hardness Removed/No Silica Removed – IX

75% Hardness Removed/No Silica Removed 75% Silica Removed/No Hardness Removed

75% Silica Removed/No Hardness Removed50% Hardness Removed/No Silica Removed

50% Silica Removed/No Hardness Removed

2/20/2014

14

Silica Overview

► Naturally occurring mineral

► Unregulated in drinking water

Not a public health concern – no Primary MCL

Aesthetic issues can be unpredictable – no Secondary MCL

No requirement for monitoring or treatment

► Commonly added to water supplies for corrosion control

► Often evaluated for performance impacts on water treatment processes

► Not typically evaluated for aesthetic impacts on drinking water supplies since there is no secondary MCL

Silica Co-Precipitation with Aluminum

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 20 40 60 80 100 120 140 160

Silica Removal

Coagulant Dose ‐mg/L as Al2O3

Alum‐ pH 7.3 Alum‐ pH 9.5 ACH‐ pH 7.3 ACH‐pH 9.5

Typical Range forSurface Water Treatment

2/20/2014

15

Silica Co-Precipitation with Aluminum

► Key Findings

> 50% silica removal is attainable … but full-scale process are very complex and expensive

• Extremely high coagulant doses required

• pH 9 before filters and 7.7 after filters

• Aluminum chlorohydrate (ACH) needed to keep Total Dissolved Solids, Sulfate, and Aluminum below their SMCLs

• Hardness is also reduced during the silica removal process

Silica Removal Processes

► Extremely complex technologies involving major solids handling and disposal

► Magnesium Co-Precipitation

Replace well pumps; add finished water pumps

Raise pH above 10.5 and add magnesium hydroxide

Settle and clarify

Lower pH back to 7.7 and add alkalinity back in

► Alum Coagulation

Replace well pumps; add finished water pumps

Raise pH above 9 and add aluminum chlorohydrate(novel technique)

Settle and clarify

Lower pH back to 7.7 and add alkalinity back in

2/20/2014

16

Costs For Silica Removal Systems

► Magnesium Co-Precipitation: $37 million

► Aluminum Coagulation: $35 million

► Reverse Osmosis: $81 million

► Costs include design, construction, permitting, construction management and 30% contingency

USEPA Office of Research and DevelopmentSpotting Analysis

Cincinnati Tap Water

Longview POE Water

pH 8.5Ca 34.7Mg 10.4Na 26.2Cl 27.6

SiO2 4.8

pH 7.7Ca 26.4Mg 5.8Na 18.0Cl 26.3

SiO2 50.0

Longview POE

w/Phos.

Customer Control Area

Customer Problem

Area

Site 17 Site 17 w/Phos.

2/20/2014

17

Comparison of Solids Formed

Since probably not practical to remove silica, could do

more study to try to change appearance upon

evaporation

Conclusions – White Spotting

► Primary cause of white spotting has been identified

Primarily associated with naturally-occurring silica, not hardness or other dissolved solids

• CaCO3 chemistry does not support precipitation • Qualitative visual comparison• USEPA solids analyses (preliminary)

Evaporative process, no evidence of accumulation in distribution system

► Softening not likely to make significant improvement

► Silica removal very complex and expensive

2/20/2014

18

Conclusions – Water Quality

► Causes of discolored water have been identified

Considerable tuberculation of unlined cast iron mains due to 67 years of corrosive Cowlitz River water

Difficulty maintaining disinfectant residuals due to changes in flow direction, water age, and pipe wall demands in Baltimore Street area

► Conditions have improved in many, but not all, areas of the distribution system

► Discolored water can be largely controlled if disinfectant residuals are maintained >0.6 mg/L

► Additional chemical treatment should be avoidable if residuals can be maintained

Recommended On-Going Water Quality Mitigation Strategies

Treatment/ Water

Chemistry

Water Age Reduction

Main Cleaning

Main Replacement

2/20/2014

19

Options/Recommendations

Chlorine Residual

(ORP)

► Raise at MFRWTP

► Trim/boost after filters

► Optimize MFRWTP operations

► Add another chemical that raises ORP

► Boost residuals within distribution system

Water Age Distribution System Solids

► Hydraulic modeling to verify flow paths

► Increase auto-flushing

► Continue bulk water flushing

► Pipeline re-routing

► Continue unidirectional flushing

► Ice pigging where chemistry has improved

► Swabbing of cement lined/plastic pipes

► Cleaning and relining unlined cast iron pipes that are structurally sound

► Ongoing pipe replacement

In Summary….

► It has been a long and difficult road….

► The primary cause(s) of distribution system water quality problems have been identified

► Effectiveness of mitigation strategies have been demonstrated

► Standard and novel approaches have been evaluated

► City has new tools to assess water quality conditions

Robust database; Tile spotting tests; Pipe rigs

► Unfortunately, white spotting issues are a nuisance that cannot be easily mitigated at the treatment plant

Avoid expensive additional treatment that likely would not be effective

► Existing treatment and O&M capabilities can be maximized to continue distribution system water quality improvement

► The Mint Farm RWTP produces water of very high quality. Process optimization is on-going

2/20/2014

20

DISCUSSION