Post on 05-Apr-2018
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MAINTENANCE &
REHABILITATION OFSEWERS, MANHOLES &
WASTEWATER TREATMENT
FACILITIES
Presented by:
BARRY BARMAN, PRINCIPAL CONSULTANT
Barry Barman & Associates, Inc
(805-368-0354)
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TOPICS
The Maintenance Survey
Alternative Methods of Remediation
Liquid Applied Coatings
Sheet Applied Products
Specifications Contractor Qualifications
Inspection
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STRUCTURES
Manholes
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STRUCTURES
Sewer Lines
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STRUCTURES
Wastewater Treatment Facilities
Concrete & Steel
Atmospheric
Immersion
Splash zone
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REHAB OF MANHOLES AND
SEWERS
Remove and Replace
Cementitious
Thermoplastic Liners
Cured-in-Place
Polymers
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MAINTENANCE OF PLANT &
EQUIPMENT
Liquid Applied Coatings (thick Film)
Epoxies
Polyureas
Elastomeric Polyurethanes
Liquid applied Coatings (thin Film)
Epoxy/urethane
Epoxy/acrylic
Acrylic/acrylic
Vinyl Sheet Products
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CONDITIONASSESSMENT
Extent of coating defects
Adhesion of coating to itself and the
substrate
Thickness of existing paint system (thin
film systems on steel)
Condition of underlying substrate
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EXTENT OF COATING DEFECTS
A Good condition; with up to 0.3% corrosion or
defects
B+ Slight touch-up; 0.3-1% corrosion & defects B Average touch-up; 1-3% corrosion & defects
B- Considerable touch-up; 3-10% corrosion &
defects
C Beyond touch-up; greater than 10% corrosion &
defects
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Typical A Condition
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Typical B+ Condition
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Typical B Condition
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Typical B-
Condition
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Typical C
Condition
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Typical
Waited Too
Long
Condition
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THICKNESS OF PAINT SYSTEM
As paint increases in thickness, the
internal stress increases
There is a finite amount of paint that canbe applied (thin film systems)
Rule of thumb - total thickness greater
than 30 mils is not recommended (forthin film systems)
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ADHESION
Adhesion pull testing
ASTM D 4541 fixed alignment
self-aligning type testers
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ADHESION
Adhesion by tape test
ASTM D 3359
Method A (X-scribe) Method B (cross hatch)
Adhesion by knife probing
ASTM D 6677 Subjective probing (scale of 2 to 10)
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CONDITION OF THE SUBSTRATE
Is there loose rust or under-film
corrosion present
Is there mill scale present
Is there an anchor profile present from
original or subsequent coating operations
Is the concrete sound
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CONDITION ASSESSMENT
OVERVIEW
CAN THE STRUCTURE BE
OVERCOATED
< 10% coating defects
minimum of 200 psi tensile adhesion
no worse than 2A or 2B by tape test < 30 mils of paint (thin film systems)
No mill scale or under-film corrosion
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THE SPECIFICATION
Work to be done
Pre-surface preparation
Surface preparation
Materials
Application
Inspection
Warranty
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QUALITY ASSURANCE
Substrate inspection
Ambient conditions
Compressed air cleanliness
Surface profile
Surface cleanliness
Mixing and thinning procedures
Application procedures Coating thickness
Holiday inspection
Adhesion
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A FOCUS ON UNDERGROUND
REHABILITATION USING EPOXY
COATINGS
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Corrosion, Infiltration and Erosion
Deterioration Underground Structures
Corrosion from MIC
Infiltration
Erosion & Abrasion
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Underground Rehabilitation Entails
Difficult Application Environments
Accessibility
Temperature and Humidity
Moisture Filled Substrates
Surface Conditions
Structure Condition
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Regardless of Technology - Over 80% of
All Failures Occur Due to Improper
Application
All technologies are installer
dependent, including sheet liners,
CIPP, fold & form, spray-appliedcementitious and polymer coatings
Project may dictate installation
(downtime, access, condition, etc.)
Equipment types are dependent onmaterial
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Epoxies
for Underground Rehabilitation
Advantages:- Moisture Tolerant
- Fast Setting and Continues Cure Underwater
- Ultra High-Build- Good Physical Properties; resilient and tough
- Excellent Chemical Resistance
- Excellent Adhesion
Disadvantages:- Require experienced skilled application
- Solvent-borne require ventilation and are affected
by moisture / humidity
- Coal tar epoxies contain carcinogens
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Proper Surface Preparation
Important Step to Achieve Coating Success
Concrete and Masonry Substrates
- Confirm substrate soundness first
- Clean and abrade to develop profile and open porosity
- Remove contaminants and existing coatings
- Stop active infiltration- Use compatible materials
Methods
- Low-High Pressure Water Cleaning
- Wet Abrasive Cleaning
- Abrasive Blast
- Secondary methods include acid etching,
degreasers, chlorine rinse, etc.
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Substrate Profile Determines
Coating Thickness
- Industry Accepted Minimum of 40-50 mils DFT for Monolithic
Coverage of Smooth Concrete
- Substrate Profile After Surface Preparation Determines Necessary
Thickness
- Structural Rehabilitation Requires High-Strength Polymer and
Additional Thickness
Desirable Coating Attributes
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Desirable Coating Attributes
Impermeable Corrosion BarrierStructural Repair
Ultra High-Build
Monolithic ProtectionQuick Efficient Application
Desirable Coating Attributes
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Desirable Coating Attributes
Moisture Tolerant
Excellent Bond
Underwater Applicationand Cure
Ceramic-like Finish
NSF/USDA
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The Job is Done When It Passes the Test
Vacuum and Exfiltration Testing- Used to evaluate integrity of installed materials
- Usually performed on manholes and pipelines
Bond Strength- Used to evaluate strength of bond between
coating and substrate
- Exposes potential surface preparation errors and
product incompatibilities
Spark Testing- Used to identify holidays or pinholes in coating
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THE STEPS TO PROJECT
SUCCESS Conduct a survey to assess conditions,
needs and limitations.
Develop a comprehensive specificationcalling for proven materials.
Have installation performed by capable
and pre-qualified contractors. Assure quality of work by using trained
and experienced inspectors.