RJN Senior Project Manager Cathy Morley will be presenting a webinar about “Inflow and Infiltration on Private Property” on Wednesday, August 10, 2016, from 12 to 1 PM Central through the ISAWWA (Illinois Section of the American Water Works Association). Registration is open until Tuesday, August 9, 2016. To register, visit this website:
We caught up with Cathy to discuss her upcoming webinar. Here is what she had to say about it.
Overall, what is your webinar about?
I’m going to talk about how you go about setting up a private inspection program to help reduce inflow/infiltration (I/I), including the program’s PR and enforcement. It will also cover flow basics and a general overview of I/I, including how we categorize public and private sector sources.
Many communities have done a lot in their collection systems to reduce I/I flow, but they have not seen the significant reduction in flows they anticipated or hoped for. This is in part because many of these areas had sump pumps installed long ago that contribute to excess flow.
There is some reticence about going into homes and asking for sump pumps to be disconnected. This webinar will discuss why you need to do that and how you go about doing that.
What should be the main focus areas in a private sector I/I reduction program?
Once you’ve done all you can do to rehabilitate the public sewer system – that is, besides the usual maintenance like cleaning and televising, which are continual processes – there are three main areas to focus on in the private sector that will make the biggest difference in shaving inflow peaks and reducing overflows: laterals, sump pumps, and foundation drains.
A History of Private Building Construction and Related Causes of SSOs
|1900s to 1920s||Many buildings constructed between the turn of the 20th century through the 1920s have some type of foundation drain, which is very expensive and complicated to remove and replace. Rather than retrofitting these buildings to remove connections, communities often anticipate that they will eventually be redeveloped and that new buildings constructed in their stead will be in compliance with current codes and ordinances that prohibit such connections.|
|1950s/1960s||Buildings constructed during the 1950s/1960s tend to have either foundation drains or sump pumps; however, many of the sump pumps were installed so that they discharge into the sanitary sewer system, contributing to inflow and SSOs.|
|1970s and Beyond||Buildings constructed after 1972 tend to be built without foundation drains, and if there is a sump pump, these sump pumps do not discharge into the sanitary sewer but rather into a storm sewer or into the surrounding yard. Since the passage of the Clean Water Act in 1972, foundation drains and sump pumps have been prohibited from discharging into the sanitary sewer in an effort to minimize the amount of clean water in sanitary systems and, consequently, the risk of SSOs.|
How Stormwater Gets into the Sanitary Sewer System from Private Buildings
What happens during rainfall to cause SSOs?
Typically during a heavy rain, it takes between 30 and 90 minutes from the onset of rainfall until flow in the sanitary sewer system reaches its peak. Depending on the characteristics of the sewershed, the flow may peak very rapidly as inflow from sources such as connected downspouts and area drains concentrate in the system, or it can peak a bit later once the ground has saturated, which is typically when sump pumps, foundation drains, and subsurface leaks reach their peak discharge. Most sanitary systems are designed, at a minimum, to handle 3 times maximum dry-day flows, but flows during heavy rains – especially in older systems with excessive I/I – can experience peak flows that are much higher than that. When the flow exceeds the system capacity, the sewers fill and become pressurized, at which point the system is at risk of overflowing, either into basements or out of manhole covers.
What’s the current state of inflow/infiltration reduction in the private sector?
Removing private downspout connections to sanitary sewers, which most communities have done in the last few decades, has helped reduce overflows, but private I/I reduction still isn’t where it needs to be. That is why we must look into disconnecting sump pumps that are illegally connected to the sanitary sewer system as well as rehabilitating laterals. Many communities prefer to disconnect sump pumps in order to reduce overflows because rehabilitating laterals is often quite expensive.
What one thing could municipalities do today to help reduce I/I in the private sector?
Plans of action are different for every community and system. Based on what they have already done to reduce inflow/infiltration, if anything, and the conditions of their system, we might have different solutions for them. Even within a single system, there might be specific areas that require different solutions because there is no absolute right answer that applies to every community.
Is there a lack of focus on private sources of I/I versus public sources?
I wouldn’t say there is a lack of focus on private sources of I/I. It’s just that in the public sector, communities feel obligated to reduce inflow/infiltration and to handle their own issues first before imposing on the private sector to do the same. It’s much easier to manage the public issues first, to put their own house in order, before asking too much of the private sector.
In addition, there is huge reluctance on the part of the public sector to make such demands on the private sector. The private sector requires much coordination and public relations to get these issues taken care of. PR is paramount to the success of a private inflow/infiltration reduction program, which adds an entirely different element to the process in comparison to the public sector.
One of the ways many communities have been handling this is through a closing ordinance or a property transfer ordinance. With these ordinances, any time a house is sold, if an illegally connected sump pump is found during the inspection, the seller is required to disconnect it before the house sale is finalized. This way, it’s less intrusive than inspecting every house at once.
Registration is open until Tuesday, August 9, 2016, for Cathy Morley’s ISAWWA (Illinois Section of the American Water Works Association) webinar “Inflow and Infiltration on Private Property” on Wednesday, August 10, 2016, from 12 to 1 PM Central. To register, visit this website: