Area Wide Testing - How Inflow & Infiltration affects our operation and your rates

Why is Inflow and Infiltration a big problem?

Inflow and Infiltration are terms used to identify extraneous water migrating into the sewer system. Inflow is the water that enters the sewer through direct connections such as downspouts, sump pumps, foundation drains, and improperly connected area drains. Infiltration is the seepage of groundwater into the pipes or manholes through defects such as cracks and broken joints.  We estimate that as much as 36-44% of the sewage processed at our treatment plants is from inflow and infiltration. Additionally, infiltration in the sanitary sewer collection system results in the need to construct larger sewers and treatment plants. Higher sewer user fees must be collected to treat the increased volume of infiltration.

What is area-wide  testing?

Area-wide testing involves testing all houses in a pre-determined area for rain and groundwater entering the sewer system. Homes are selected geographically by sewersheds, or homes whose sewers drain to a common point. This method has the greatest impact to the system as a whole since it allows us to accurately measure the amount of extraneous water we remove from infiltrating our system.

How are neighborhoods selected?

Neighborhoods are selected for testing based on the amount of inflow and infiltration suspected in the sewershed according to engineering studies. A sewershed is an area of homes that drain to a common area, much like a watershed. We plan on starting with neighborhoods identified as contributing the most inflow and infiltration first. Your neighbor may not be served by the same sewer line as your home.  They will be tested based on the ranking of their sewershed. Ultimately, we plan on testing all properties identified as contributing to the inflow and infiltration problem.  

How will testing be done?

Testing will be performed by Sanitary Authority personnel or specialized contracted testing companies, depending upon the size of the sewershed. Typically, testing will be done during business hours, 8:00 am - 4:00 pm and will encompass all the homes served by a particular sewer line.  We may ask that you not use water during the test so as to not create a false positive.  During wet weather events, such as snow melt and heavy rain, we may inspect during other hours of the day due to favorable conditions for testing.  We will try to minimize any inconvenience to you and your neighbors.

What about the Sanitary Authority sewers?

The Sanitary Authority realizes the importance of maintaining its infrastructure and leads by example.  The maintenance and repair strategy for the sewer system is to televise and inspect 24,000 feet of sewer each year and rehabilitate 12,000 feet of sewer each year.  

Reducing the effects of Infiltration

The Sanitary Authority undertook a study of its service area to determine sewersheds, or areas, that are contributing high rates of Inflow & Infiltration.  This study ranked the sewersheds by the amount of groundwater they contribute to the sewage system.  Through a systematic approach of testing and elimination of these sources of  infiltration, the Sanitary Authority will be able to control costly treatment plant expansions and upgrades. These costs could reach into millions of dollars if left unchecked.

Reducing the effects of nutrients

Upcoming Environmental Protection Agency regulations will require the Sanitary Authority to decrease the amount of nutrients, specifically phosphorous and nitrogen, that enter our waterways.  These nutrients are found naturally in human and animal wastes. Adversely, excessive lawn fertilization, poor agricultural management or malfunctioning septic systems can result in nutrient runoff during rain events.  If we work together to reduce the volume of nutrients and wet weather infiltration entering the sewage system, the Sanitary Authority will be able to meet nutrient levels being set by the EPA at a reasonable cost.  Adversely, if the infiltration is not reduced significantly, additional treatment costs to control nutrients and infiltration will be required.  These costs will need to be passed on to all ratepayers in the form of higher sewage bills.