Metallurgy and Corrosion for Waste Water Facilities

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2 Metallurgy and Corrosion for Waste Water Facilities 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 Presented by: John French, PE Corrosion Engineer

3 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 Orange County Service Area San Diego Orange County, California

4 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

5 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

6 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

7 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

8 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-toservice for concrete and steel rehabilitation

9 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 surfacetolerant coatings and manual surface preparation Test for lead, chromium, cadmium, barium in existing coating systems

10 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

11 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/cm 2 Lack of full-time coating inspection During installation, keep stainless steel contamination-free

12 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 PVCliner 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

13 Common Issues and Problem Areas (continued) Limit visible fugitive dust emissions during dryabrasive 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

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15 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 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

16 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 PVC linings 50 years High-build polyurethanes/epoxies Submersion thin-film epoxies years 15 years Architectural coatings 5-10 years 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

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19 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

20 Capital Improvement Program (CIP) and Asset Management

21 Annual Validation Process CIP Revised CIP Analysis

22 What are the AM CIP tools? CLR confidence level rating BRE business risk exposure LCC life cycle cost analysis Staff/Management Judgment

23 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

24 Business Risk Evaluation BRE s provides data to management Identification Recognition Measurement Evaluation Spreadsheet model Triple bottom line consideration entries Social, economic, environmental

25 Asset Management Matrix

26 Corrosion Management Strategy Research Capital Project Development Modeling Assessment

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

28 Modeling Select parameters Model parameters Prioritize assets based on risk score Schedule assessment

29 Assessment Develop Scope of Work Inspection Visual Confined space, SCBA Robotic camera (CCTV) Remote Operated Vehicle (ROV)

30 Capital Project Development Justify and develop a CIP business case Condition evaluation Consider alternatives Cost estimates Submit project request documents

31 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

32 Asset Management Systems Summaries Collections System Preliminary Treatment Primary/Secondary Treatment Solids Handling Utilities Central Power Generation System Ocean Outfall

33 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

34 OCSD Planning Department John French, PE Corrosion Engineer