Standardizing Sanitary Sewer Assessment by Establishing Condition and Criticality Factors

The City of Baltimore, Maryland entered into a Consent Decree which required the elimination of sanitary sewer overflows and the control of combined sewer overflows. The Consent Decree specified various work tasks to be performed including a complete assessment of the collection system and the development of an overall corrective action plan. Sewer assessment presented challenges because of the significant volume of data to be collected. In addition, simultaneous implementation of all recommended improvement projects and/or other corrective actions will be cost-prohibitive. As a result, a standardized methodology was utilized which evaluated and prioritized collection system components based on both condition (i.e. probability of failure) and criticality (i.e. consequence of failure) criteria developed and weighted through a stakeholder's involvement process. A series of GIS tools were developed to automate application of the condition and criticality methodology and develop maps to identify and present results of the sewer assessment.