Public Works is continuing an Infiltration and Inflow (I&I) Reduction Program throughout the City. This page contains information on frequently asked questions concerning I&I and the City's approach to addressing the issue.
What types of problems are there in my neighborhood?
A wide range of problems can occur due to I&I:
- Back-ups into people’s homes and businesses
- Sanitary Sewer Overflows (SSOs) into yards, streets, and streams
- Lack of wet weather sewer capacity in the system
Why are these problems happening?
Separated sanitary sewers are designed to convey only wastewater. However, many of these "separated" sewers also convey groundwater and storm water that enter through leaky pipes, improper storm drain connections, and other means. This excess water, called inflow and infiltration (I&I), takes up capacity that could otherwise be used for wastewater alone and generates the need to build added capacity in pipelines, treatment plants, and other wastewater facilities.
What is inflow and infiltration?
Inflow and Infiltration: (I&I) are terms used to describe the ways groundwater and storm water (“clear water”) enters the sanitary sewer system.
Why is inflow and infiltration a problem?
Public Health and Environment: Additional flow caused by I&I often makes the sewer system reach or exceed capacity, resulting in basement backups and overflows to the environment, and is harmful to public health.
Additional Costs: Extra water in the sewer takes up capacity in the sewer pipes and ends up at the City’s wastewater treatment plant where it must be treated like sewage, resulting in higher treatment costs. Also, when this extra water makes it into the sewer system, it requires new and larger wastewater facilities to convey and treat larger volumes of flow, resulting in higher capital expenditures.
The City is performing inspections and testing in an effort to locate, identify, and correct improper connections and defects that cause I&I so that system capacity improves and overflows and backups are eliminated. The following inspection methods will be used in your area:
- Flow Monitoring
- Smoke Testing
- Manhole Inspections
- Internal/External Building Surveys
- Television Inspection (CCTV) of Sewer Mains
- Television Inspection (CCTV) of Service Laterals
- Dyed Water Testing
- Wet Weather Inspections
Inspection activities will occur in existing public right-of-ways, sanitary sewer easements, and on private property.
At the completion of inspections, problem sanitary manholes and sewers are identified for repair. Currently, some sections of the City's system are in the study phase, while others are further along the process and are in the construction phase to remedy the I&I concerns.