DETAILED DESIGN MODELING FOR LARGE SCALE CSO FACILITIES - FACING OUR FEARS AND SIMPLIFYING ASSUMPTIONS

The primary purpose for computer modeling of public systems is not to develop the most whizbang analysis tools, but rather to provide information to assist project managers and agency managers in making decisions. Our role is to help make decisions. Often those decisions are for small tasks that serve a larger project. However, modeling is also called upon to help guide the policy of an agency or a wide reaching conceptual plan. In Portland, an expensive Combined Sewer Overflow (CSO) Program that will be integrated with watershed management and salmon Endangered Species Act (ESA) response plans has resulted in a situation where modeling and Geographic Information System (GIS) analysis are being used to make decisions across a wide range of levels, from policies to conceptual plans to overall predesigns and finally detailed design. This paper presents the Portland Combined Sewer Modeling System and how it is being used to support detailed design projects for CSO facilities, public and CSO facilities plans, and significant policy directions for the Bureau of Environmental Services (BES).