Metallurgy and Corrosion for Waste Water Facilities

Presented by:

John French, PE Corrosion Engineer 714-593-7112 jfrench@ocsd.com

www.ocsd.com

Presented to: California Water Environment Association, SARBS Chapter Odor Control, Secondary Treatment, Math, and Plant System Maintenance The Phoenix Club, Anaheim, California June 5, 2013

OCSD Service Area 480 square miles 207 million gallons per day 2.6 million population 21 cities, 3 special districts 580 miles of sewers 15 pump stations 2 treatment plants

Los Angeles

San Diego

Orange County

Orange County,

California

Service

Area Service

Area

Introduction

• Materials Selection for Waste Water • Wetted • Un-wetted • Underground

• Coating Systems, New and Rehab • Common Coating Systems • Expected Coating System Life • Coating Demolition

• Common Issues and Problem Areas • New Construction • Rehabilitation

• Developing a Systematic Approach

Materials Selection– Wetted

• Non-metallic preferred • PVC-lined concrete, coated concrete • Coated carbon steel • Stainless steel bar screens, gates, difficult

to coat structures; typically use 316, though depending on chlorides

• Salt water dictates duplex (2205 shown) or super duplex grades

Materials Selection– Un-wetted

• Coated steel is often the economical choice

• Stainless steel, 304 for mild exposure, 316 near marine environments

• Non-metallic materials used with care

• Uncoated aluminum, with adequate air exchanges in clarifiers

• Concrete remains uncoated to allow for inspection

Materials Selection– Underground

• HDPE, PVC-lined concrete, carbon-fibre, composites

• Coated and lined steel with cathodic protection (CP) • Electrical continuity of structure • Electrical isolation from extraneous

grounded structures • Sacrificial CP preferred • Extensive testing required

• Avoid buried stainless steel

Coating Systems– Wetted

• Coal-tar epoxy for older, existing

structures • Thin-film low-VOC epoxy for new

construction • For pipeline interiors, wet wells,

junction structures, digesters, clarifiers, plural-component applied high-build epoxies and polyurethanes with rapid return-to-service for concrete and steel rehabilitation

Coatings Systems– Un-Wetted

• Zinc-based primers, organic/inorganic • Intermediate epoxy coats with

aliphatic polyurethane top coating for gloss and color retention

• Maintenance coating with surface-tolerant coatings and manual surface preparation

• Test for lead, chromium, cadmium, barium in existing coating systems

Full-Time Coating Inspection

• NACE CIP III third party inspectors • Qualified in-house coating inspectors • Pre-job meeting

• Daily Inspection Reports • Provisions for failure analysis • Specify using standards:

ASTM, SSPC, NACE, ICRI, ACI

Common Issues and Problem Areas

• Lack of pre-design testing—concrete coring (pH, chlorides), corrosion loss, coating thickness

• Lack of concrete surface preparation during rehab—use inspection blast panels and minimum pH 10 (new concrete: pH 12.4)

• Surface contamination, concrete and steel—use Chlor*Test or similar methods for chlorides, sulfates, nitrates tested to 5 μg/cm2

• Lack of full-time coating inspection • During installation, keep stainless steel

contamination-free

Common Issues and Problem Areas (continued)

• Measure degree of concrete removal during demolition using pre-set pins or pilot holes

• For new construction, specify parge application on concrete surfaces, same as for rehabilitation projects

• Specify contractor-provided full confined-space access and support during construction

• Failure to weld, and/or failure to inspect PVC-liner system weld strip during construction

• Coating failure-mode is in splash-zone area of clarifiers which are covered for odor-control—cathodic protection not used because it is not effective in splash-zone

Common Issues and Problem Areas (continued)

• Limit visible fugitive dust emissions during dry-abrasive blasting operations with dust control

• Specify quantities of sharp edges and weld spatter for removal during rehabilitation work

• Failure to verify electrical isolation for cathodically protected structures from extraneous structures prior to backfill

• Failure to test for integrity of electrical continuity joint bonds on cathodically protected structures prior to backfill

• Rehabilitation—For steel, use ASME B31G or API 653 to calculate maximum allowable pit depth

Coating Demolition

• Dry-abrasive blasting with non-recycled slag common for steel and concrete—provide full dust containment

• Combination of 30 kpsi ultra-high pressure water jetting (SSPC-SP 12/NACE No. 5) for concrete demolition with dry- abrasive blasting after parge coat to achieve ICRI 310-2 CSP-5 surface finish prior to coating

• Impact methods of coating removal, bushing (bush-hammering), scabbling (scappling), tend to damage concrete substrate, requiring subsequent re-blasting

Predicting Coating Life • New coating systems, changing regulations, affect predicted

coating life, and application conditions are a significant factor • Coatings and linings life general guidelines

• Periodic inspection of coatings systems as part of an Asset Management Plan is the most useful tool in determining coating and lining life

• Methodologies for Predicting the Service Lives of Coatings Systems, Jonathan W. Martin, Sam C. Saunders, F. Louis Floyd, John P. Wineburg, Federation of Societies for Coatings Technology

PVC linings 50 years

High-build polyurethanes/epoxies 20-25 years

Submersion thin-film epoxies 15 years

Architectural coatings 5-10 years

Developing a Systematic Approach Asset Management Plan is a

long-range planning document providing a framework to understand:

• Inventory and condition of physical assets

• Present and future demands • Estimated short- and long-term

financial needs

Capital Improvement Program (CIP) and Asset Management

Annual Validation Process

CIP Revised CIP

Analysis

What are the AM CIP tools?

• CLR – confidence level rating • BRE – business risk exposure • LCC – life cycle cost analysis • Staff/Management Judgment

The Confidence Level Rating

• A measure of the current quality of project concept • Service levels, failure modes, risk,

consequences (demands) • Costs, delivery options, project

alternatives (state of development) • Spreadsheet model

• CIP and business efficiency projects

• WBP or deliverable based option

Business Risk Evaluation

• BRE’s provides data to management • Identification • Recognition • Measurement • Evaluation

• Spreadsheet model • Triple bottom line consideration

entries • Social, economic, environmental

Asset Management Matrix

Corrosion Management Strategy

Research

Modeling Capital Project Development

Assessment

Research

• Collect and organize data • GIS maps • Record drawings • Standard specs and drawings • O&M information • Staff and consultant input

Modeling

• Select parameters • Model parameters • Prioritize assets based

on risk score • Schedule assessment

Assessment

• Develop Scope of Work • Inspection

• Visual • Confined space, SCBA • Robotic camera (CCTV) • Remote Operated Vehicle (ROV)

Capital Project Development

• Justify and develop a CIP business case • Condition evaluation • Consider alternatives • Cost estimates • Submit project request documents

Sustainability

Long-Term Asset Obligations

• Full life cycle of assets modeled for 100 years

• High confidence level in: • Timing predictions in first 20 years • Actual renewal needs

• Replacement intervals • Civil assets: long life,

slow replacement • Mechanical, instrumentation,

fast replacement

Asset Management Systems Summaries

• Collections System • Preliminary Treatment • Primary/Secondary Treatment • Solids Handling • Utilities • Central Power Generation System • Ocean Outfall

Current and Future Staff Driven Efforts

• Developing asset management system summaries for sewer systems, facilities and information technology

• Identifying assets for rehab/renewal for the next 10 years

• Updating financial information projections

• Developing business risk evaluations for plant process lines

OCSD Planning Department John French, PE

Corrosion Engineer 714-593-7112

jfrench@ocsd.com www.ocsd.com