Project Background

The Louisville and Jefferson County Metropolitan Sewer District (MSD) provides wastewater, drainage, and flood protection services to over 700,000 people in Kentucky, USA. In 2017, MSD released their Critical Repair and Reinvestment Plan. This plan identified a wide variety of projects to be implemented in its systems over the next 20 years, addressing a range of public health, service, and safety-related issues. Following the development of the project plan, MSD was left with the challenge of identifying which projects to prioritize each year, based on their financial budget (which has a degree of uncertainty associated with it). Furthermore, the nature of the projects identified will continue to change and evolve in response to business drivers, regulatory pressures, infrastructure deterioration, and customer service needs. MSD was seeking a tool that could help them adaptively prioritize a collection of projects each year to minimize risks and maximize benefits while meeting annual financial constraints.

Project Scope

Optimatics worked with MSD to develop a Program Scheduling software module, utilizing Optimatics’ optimization framework.

The inputs into the module included a list of all of the identified projects, their anticipated costs (as a time series), a monetized risk before and after project implementation, and a benefit score. Monetized risk was calculated based on an adaptation of the US EPA SIMPLE approach, where each project is assigned a probability of failure, consequence of failure, and mitigation factor.

The consequence of failure was monetized based on a range of environmental, social, and economic criteria. Probability of failure considered the percent remaining life of the asset, current condition, and design capacity. Benefit, or community value, was assessed against up to 33 different factors covering a range of categories (sustainability, public health protection, etc.).

Outcomes

Using the AA Program Scheduling module, MSD was able to produce a Pareto front, which illustrates the best possible combinations of projects to implement each year to minimize cost and maximize benefit, without exceeding budgetary limits.

MSD has used AA Program Scheduling to inform its capital investment plans. The module allowed them to transparently provide a defensible capital plan with justifiable project selections. Amongst other things, the module has provided tremendous insight into the relative combined impacts on risk and benefit that different investment strategies have. Outputs from the software module have been used to help convince executives of where money should be most beneficially appropriated.

It has been found that AA Program Scheduling is easy to set up and use, runs quickly, and provides a consistent and transparent framework for multi-criteria, multi-objective optimization.