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
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► 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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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