maint & rehab wwt

7/31/2019 Maint & Rehab WWT

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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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Impermeable Corrosion BarrierStructural Repair

Ultra High-Build

Monolithic ProtectionQuick Efficient Application



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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.

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