Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Session Overview
Session 12B: Planning, Resiliency, Climate Science: Planning
Tuesday, 10/Sep/2019:
10:30am - 12:00pm

Session Chair: Susan Schlangen, Water Systems Consulting;
Location: D137-138

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10:30am - 11:15am

A Comprehensive Planning Approach to Cost Effectiveness Analysis (Conveyance, Treatment, & I/I Reduction)

Shad Roundy1, Jessica Rinner2

1Jacobs; 2Clackamas County Water Environmental Service; ,

Many utilities face decisions on capital and O&M expenditures related to treatment capacity upgrades, trunk sewer and pump station condition and capacity improvements, and I&I reduction improvements. Critical questions for decision makers include:

What should the target I&I reduction and timing be to offset or delay conveyance and treatment costs?

Where do I&I reduction costs offset potential growth-related expenditures?

What are the impacts of system I&I degradation and remaining useful life of infrastructure?

How does a comprehensive program encompassing treatment, conveyance, and I&I reduction affect decision on rates?

What opportunities exist to implement, incentivize, and accelerate I&I reduction?

This presentation will focus on recent efforts in Clackamas County to evaluate I&I by sub-basin and compare capital and O&M costs encompassing conveyance, treatment, and I&I reduction improvements. The analysis utilized hydraulic modeling and condition and age assessments to populate a cost effectiveness model. Statistical analysis was used to evaluate system risk and infrastructure degradation. 40 sub-basins were sequential tested for three I&I reduction levels and five timeframes to develop cost effectiveness curves. These curves were used to select an optimal target reduction and timeframe for implementation. The I&I cost effectiveness analysis is being used to inform a capital improvement program and promote I&I reduction in contributing communities.

11:15am - 12:00pm

Balancing Wastewater Collection System and Treatment Plant Investments in Sandy, Oregon

Preston Van Meter1, Mike Walker2, Yarrow Murphy1, Rob Lee1

1Murraysmith, Inc.; 2City of Sandy, Oregon; , ,

As one of the top 5 fastest growing communities in Oregon, the City of Sandy is facing the difficult challenge of expanding the City’s wastewater system to provide for growth while maintaining an aging wastewater collection system subject to high rainfall derived inflow and infiltration (RDII). In the face of compliance issues at the City’s wastewater treatment plant and a mutual agreement and order (MAO) with Oregon DEQ, the City turned to Murraysmith to assist in the preparation of a comprehensive Wastewater System Facilities Plan (WSFP) to provide a roadmap for investments in the City’s wastewater system over the next 20 years as the City population doubles.

At the heart of Murraysmith’s wastewater system planning approach is a focus on balanced investments in wastewater treatment and collections, looking at a series of alternatives ranging for full collection system rehabilitation and replacement to a “pump and treat” scenario primarily focused on treatment capacity upgrades. Ultimately, an optimized approach balancing collection system rehabilitation to reduce RDII coupled with cost-effective wastewater treatment plant upgrades was selected by the City for implementation.

The presentation will focus on the collection system modeling approach and development of rehabilitation scenarios, wastewater treatment plant expansion options for those scenarios and the phasing of recommended upgrades to help reduce impacts of the recommended plan on community ratepayers to the maximum extent possible.

An overview of the recommended plan will be provided including full rehabilitation of wastewater collection system mains and laterals in the City’s two largest sewersheds, construction of a new satellite MBR treatment facility with diversion pump station, new discharge to the Sandy River and continued utilization and rehabilitation of the City’s existing wastewater treatment plant.

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