Large In-Plant Pump Station Condition Assessment: It's All in the Planning

Objectives: Black & Veatch (BV) provided condition assessment of three separate large (200+ MGD each) critical operating pump stations (PSs) within the operating San Jose-Santa Clara Regional Wastewater Facility. The primary objective of the project was to assess the conditions of the existing mechanical, electrical, structural, and instrumentation components of each PSs with the goal of extending the life of the assets an additional 30+ years. The assessment, findings, and analyses were utilized to provide the following information to City of San Jose (City):

*Condition assessment scoring and estimated remaining life of PS components

*Class 5 planning level replacement/rehabilitation costing for each component

*Recommended project implementation and sequencing schedule Our presentation will focus on:

*PS size and complexity

*Planning approach - criticality of client engagement

*Tools and analyses methods

*Recommended project implementation approach for each PS

*Importance and value of performing condition assessments Status: All three PS condition assessment field work and two of the three PS condition assessment reports are completed. The third PS condition assessment report will be finalized by March 2024. Methodology: Our project required thorough and detailed planning to ensure condition assessment activities were closely coordinated with operations and maintenance to minimize plant disruptions. BV, acting as the prime consultant, assembled a team of subject matter experts to successfully plan and complete the project. Our roadmap (Refer to Figure 1 in WEFTEC abstract submission page) for successfully implementing the project included three phases: Planning Phase, Field Work Phase, and Documentation and Reporting Phase. This strategic approach brought in all necessary stakeholders for knowledge transfers and for important decision making. Our client engagement approach focused on safety and minimizing unknowns and uncertainties when performing site work. The detailed Planning Phase included items such as assessment and testing approaches, identifying division of responsibilities, work sequencing, and safety, confined space, and wet well dewatering planning. We coordinated a condition assessment scoring system with the City, which included a 1 to 5 rating system (Refer to Figure 2 in WEFTEC abstract submission page). The Field Work Phase included individual mobilizations for each PS. A combination of destructive and non-destructive assessment methods were used to assess structural, mechanical, electrical, instrumentation, and hazardous components. The Documentation and Reporting Phase included separate Condition Assessment Reports and review workshops for each of the PSs assessed. Findings: Generally, concrete structures appeared to be in a moderate condition. Minor cracking was observed, which appeared to be due to shrinkage and typical of the structures' age. Localized repairs are needed to address groundwater seepage. Within confined spaces, concrete had minor surface degradation where coatings were not present. Concrete core samples indicated concrete was durable, with compressive strength over 7,000 psi and pH and chloride concentrations below corrosion thresholds at the reinforcing steel depth. Thickness testing measurements were within manufacturer tolerance of the steel piping nominal thickness values. Internal inspections found evidence of coating deterioration and surface corrosion. Within confined spaces, piping had moderate external corrosion where coatings have deteriorated. Electrical equipment have been in continued operation for over 15 years. Inspection observations found interior dust build up, debris in the power cells, and fuse cap discoloration. Most instrumentation were in good condition, with no issues indicated by City staff. While in fair/good condition, some older instruments were no longer produced or serviced by the manufacturer. Hazardous material testing found that coatings were determined to contain lead paint. Asbestos and polychlorinated biphenyls were not identified. The older PSs (vintage 1960's and 1970's) were found to require pump replacement due to condition, while the newer PS (vintage 2008) had pumps that were in good condition. Figure 3 illustrates examples of the various observations made during field assessments. Figures 4-7 summarizes the recommendations for the Filter Influent PS: cost estimate by condition score, cost estimate by discipline, overall recommendations summary, and the recommended 0-5 year constructability grouping implementation recommendation. Figures 8-15 summarizes the recommendations for the Raw Sewage PS: cost estimate by condition score, cost estimate by discipline, overall recommendations summary, and the recommended multi-year constructability grouping implementation recommendations. Significance of the Project: The information and recommendations provided to the City will be utilized by management and stakeholders for future capital improvement planning. This proactive condition assessment provides the following benefits to City, which would be applicable to other Utilities:

*Improves accuracy of future CIP fiscal year expenditures

*Improves ability to define the scope of the future improvements projects

*Reduces change order risk by documenting as-is conditions, such as equipment and piping condition, and presence of hazardous materials