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Condition Assessment: City of Bellingham Supply System 2015 PNWS-AWWA Conference
2 Presentation Title
Presentation Topics
1. Background
2. Condition Assessment
1. Wood Stave Intake
2. Tunnel
3. Screen House
4. Pipelines
1. Industrial (48” CCP)
2. Municipal (66” steel)
3. Acknowledgements/
Questions
3 PNWS-AWWA 2015
City of Bellingham
• Population = 83,000
• 13 pump stations
• 13 storage tanks
• 400 miles of pipelines
• One supply system
– Lake Whatcom
– Wood stave intake pipeline
– Tunnel
– Screen House
– Industrial supply pipeline
– Municipal supply pipeline
Lake Whatcom
Supply
Facilities
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Water Supply System
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Wood Stake Pipe Intake
Wood
Stave
Pipe
Intake
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Wood Stave Intake
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Wood Condition
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Original Steel Rods and SST Bands
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Condition of Steel Rods
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Flange
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Sponge Inside Intake Pipe
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Wood Stave Intake: Results
• Wood in good condition
– Support structural components
– Stave pipe (interior and exterior)
• SST bands in good condition
• Original steel fasteners in fair condition
• Some original steel rods corroded to failure
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Tunnel
Tunnel
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Tunnel Inspection Activities
• Underwater Laser Scanning (2012)
• Man-Entry Inspection (2015)
• Tunnel Data Analysis
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Tunnel Profile
7,600 LF
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Tunnel Section
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Laser Scanning: Field Photos
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Laser Scanning: Data Gathered
5 ft
9 ft
3 ft
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Laser Scanning: Example Output
REFLECTION OF CRAWLER
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Laser Scanning: Interpretation
West
No Defect
s 81%
Mild 12%
Moderate 5%
Severe
2%
East
No Defect
s 68%
Mild 17%
Moderate 13%
Severe
2%
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Man-entry Tunnel Inspection
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Man-entry Tunnel Inspection
Stationing Crew
Inspection Crew
Insertio
n P
oin
t
Extra
ctio
n P
oin
t
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Man-entry Tunnel Inspection
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Tunnel: Results
• No major deformation
• Isolated liner defects
• Limited, minor fracture acceleration
• Next Step: Point repairs, monitoring plan
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Screen House
Screen
House
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Screen House
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Screen House Inspection Elements
• Traveling screen
• Slide gates
• Concrete structure
• Steel pipes
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Travelling Screens
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Slide Gate
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Internal Steel Pipe Condition
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External Steel Pipes Condition
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Screen House: Results
• Concrete structure in good condition
• Travelling screens in good condition
• Slide gates
– Heavy tuberculation
– Some corrosion loss
– Replacement needed
• Steel pipes (3) need rehabilitation
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Industrial Pipeline
Industrial
Pipeline
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Tiered and Adaptive Plan (TAP)
• Visual
• Corrosion Survey
Tier 1
• Test Pits
• Destructive Testing
Tier 2
• Specialty Tools
Tier 3
Lowest Cost, Identify Issues Higher Cost, Design Data
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Soil Corrosivity Mapping Along Industrial Pipeline
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Existing Cathodic Protection System
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Existing CP Test Stations
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Industrial Pipeline: Results
• Existing CP system is operational and
effective
• Condition assessment complete after Tier 1
• No further condition assessment warranted
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Municipal Supply Pipeline
Municipal
Pipeline
(Raw
Water)
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Tier 1 External - Soil Corrosivity
1,800
49,200
1,800
1,300
3,600
2200
16,300
2900
5600
1,000
10,000
100,000
0+00 2+00 4+00 6+00 8+00 10+00 12+00 14+00
Soil
Res
isti
vity
(o
hm
-cm
)
Pipeline Station
5 to 7.5 ft depth
Slightly Corrosive
Moderately Corrosive
Very Corrosive
Extremely Corrosive (<1,000)
Screen House
Trail at Silver Beach Road
Trail at WTP Access Road
ARV
WTP
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Tier 1 External -Stray Current Adjacent Industrial Supply Pipeline CP System
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Tier 2 – Internal Condition
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Tier 2 Internal – Concrete/Steel Pipe Joint
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Tier 2 Internal – Pipe Wall Thickness
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Tier 2 Internal - Pitting
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Tier 2 Internal – Coal Tar Lining
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Tier 2 Internal – Cement Mortar
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Municipal Pipeline: Results
• External Tier 1 Complete
– Corrosive soils
– Stray current
• External Next Step: Tier 2 Test Pits
– Evaluate coating/pipe condition
– Test for stray current
• Internal Tier 2 Inspection
– Coal tar enamel lining – excellent condition
– Minor corrosion at coating defects
– Localized repairs at few joints required
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Acknowledgments
50 Presentation Title
Thank You
Dan Buonadonna, PE
Jerry Duppong
Phil Martinez, PE
Bill Evans
