Proposed inspection program would track flaws in the sewer system

If terms like sewer “inflow and infiltration” already bring a glaze to your eyes, you might want to snap out of it. The city is looking to shine a light on what lies beneath Eden Prairie. To do that, it's going to need the cooperation of EP’s homeowners with an inspection program that could roll out next year.

First up in October, the City Council will go over the first reading of an ordinance that would require compliance with such an inspection program. Before that time, the city of Eden Prairie is hoping to educate its citizens on inflow and infiltration 101.

I and I

Eden Prairie is not alone in facing the issue of tracking water inflow and infiltration (or I and I). In fact, the program stems from a mandate from Metropolitan Council Environmental Services.

The region is facing a sewer system that is far more taxed than capacity projections would imply. The reason? Clean water entering the supposed-to-be closed sewer system.

What is termed inflow of clean water means that it's directly leaking into the system, while the term infiltration means that it's seeping into the system. Overextending the sewer system can cause a number of problems along with undue wear and tear on a system that would be very costly to replace early.

Bottom line: The Met Council sees the most cost effective way to address this problem is by mandating that cities cut the amount of clean water entering the sewer system.

 “It’s not an unreasonable request,” said Public Works Director Gene Dietz.

The city doesn't have much choice in compliance with the issue. According to the staff report, the city faces surcharges of $550,000 a year for five years to work on it.

“What we have to do annually is show how much we’ve spent toward resolving the problem,” added Dietz.

Part of resolving that is to fix public utilities, but the city's consultant on the project estimates that 65 percent of the problem comes from the private side, specifically sump pumps that illegally connect to the sewer system and leaky service lines.

“The biggest issues of sump pumps and service lines that leak have not been addressed,” said Dietz

Inspections

Should the city approve an ordinance this fall, it does not mean every house will be inspected initially. Based on flow monitoring, the city now knows what section of town has the highest flow of water into the system.

According to that map, sections of town more vulnerable to I and I include central and northwest parts of Eden Prairie. City staff know where, they just don't know why.

According to Dietz, causes for inflow and infiltration could be sump pumps, service lines, leaky manholes, catch basins connected to the sewer line or roof leaders from commercial buildings connected to sanitary sewer.

Certain portions of town are more likely to encounter I and I problems because of soil conditions, according to Dietz.

Some of those things will be easy to fix, some of it will be more expensive but “we need to figure out what’s the most common problem and then begin to focus on that.”

A scheduled inspection would most likely involve verification that a homeowner's sump pump is not connected to the floor drain or laundry tub, then a camera would be put into the service line to check and see if there are broken service line pipes, he said.

According to an e-mail from Dietz, he expects the city will eventually inspect all homes, "especially for sump pump connections.  But, this first phase will determine the need/value  of televising the service and how quickly we need to proceed, which is the major cost factor in the inspection process."

The main point he wanted to get across is that it's illegal to connect sump pumps to the laundry tub or the floor drains. An inspection program is not a punitive thing the city is looking to do, but rather in response to a reality it faces, he added.

“That we need to remove this excess water from the sewer system.” 

Infiltration and Inflow (I and I)What is it? Clean water that ends up in the sanitary sewer system. Metropolitan Council Environmental Services is looking to cut the amount of I and I that ends up in the sewer system. Over time, if not addressed, the issue of too much water in the sanitary sewer system could lead to sewage leaks, wear and tear on infrastructure and costs to the public.

How does it impact the city? The city of Eden Prairie is responsible for cutting the amount of I and I that enters the system. The city faces an annual $550,000 surcharge if it does not address the issue.

How does it impact the homeowner? The city will be studying how to cut down on infiltration and inflow by inspecting both public and private systems. As part of a proposed ordinance, homeowners could face a surcharge if they do not comply with inspections of sump pumps and service lines.

What's next? The ordinance requiring compliance with inspections is up for a first reading by mid-October. Look for more details to emerge in the coming months.