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Video of air gap problem

Posted by Judy Hanway on 12 Mar, 2014
Category: No category

Hello all. 

Lynn Lumbard, a friend of mine, who lives in the Dicken area, just sent me this video. The video is short but it shows one burst of water spewing out as the pump discharges. The water has damaged the insulation in the wall of her house. 

The pipe leading from the house to the curb drain is frozen (at least that is what Hutzel told her), so the water is pouring out of the air gap. She said the City has been advised (Nick, Robert, have you heard about this?) and that Hutzel has been out and connected a pipe from the exterior of her sump discharge to the middle of her front yard. This new pipe sits on the surface and water is pouring out onto the yard and sidewalk.

She also said 2 people she knows have it worse than she does.

Comments

Robert Czachorski on 12 Mar, 2014:

I would like Greg to come take a look at it right away. To understand what is happening, an examination is needed. The video is not enough to verify the issue. It would be like diagnosing a sick patient from a video of the symptoms. Judy – can you arrange a visit with Greg?

Judy Hanway on 12 Mar, 2014:

I have emailed Lynn and will let you know.

Jim Osborn on 12 Mar, 2014:

Robert is correct. It needs to be examined, and we may not know until everything has thawed out My first thought or speculation is that the pipe is shallow in the ground, and the contractor did not give it a steady slope, allowing it to drain completely after each discharge. Any trapped water at a shallow level could freeze.

If water is coming out, then the system did not freeze at this air gap, but elsewhere.

Joe Conen on 16 Mar, 2014:

Regardless of the cause of water exiting through the air gap, it seems like a better design for such an overflow would be a good idea. It would not be hard to have one that directs flow away from house. I may attach a photo of an example later, if I can get onto my computer.
Joe

Robert Czachorski on 3 Apr, 2014:

Greg Marker investigated the occurrence of this issue on March 12 and 13 and the results of his investigation are outlined in the attached memo.  Please let us know if you have any questions.

Take care,
Robert

Judy Hanway on 8 Apr, 2014:

This entire situation is very upsetting to me for the following reasons:

1. Homes were badly damaged by the freezing of this curb drain.
2. City workers who came and cleared the curb drain with pressurized water, told the homeowners on Avondale that this was not the only place where this had happened.
3. In how many locations was there freezing of curb drains?
4. I would not want my home to be connected to a curb drain that could potentially freeze. What could be done to prevent the freezing? Are there warming devices (similar to those people put on roofs to prevent ice dams) that could be installed to correct this problem?
5. The frost line in Michigan is much lower than 1.5 -2 feet. Why were the curb drains not installed deeper--ie, at 42+ inches? 
6. We can expect further weather extremes in the future and could possibly have more harsh winters like this. The response from Ms. Warrow that this is a rare occurrence doesn't do anything to solve the problem or to empathize with the homeowners.
7. The discharge lines were temporarily extended over the front lawns of the homeowners and I understand that at least one of the homeowners received a notice from the City warning about the ice on her sidewalk. 

Mark Wagner on 8 Apr, 2014:

Judy,

I thought I had asked the question of the curb drain line depth at a previous meeting as was assured that the curb drain lines had been installed below the frost line.

Judy Hanway on 13 Apr, 2014:

I have 2 additional questions:

How many different contractors installed the curb drains in Ann Arbor?
What was the specified depth for burial of the curb drains?

Thanks.

Lori Byron on 29 May, 2014:

Q. How many different contractors installed the curb drains in Ann Arbor?
A: There have been 3 different contractors.

Q. What was the specified depth for burial of the curb drains?
A: This curb drain is to be installed, using an approved directional drilling (trenchless) method for the specified pipe at a depth 2-6 feet between existing storm sewer catch basins or other approved structures as directed by the Project Engineer. A minimum grade of 1% (one percent) shall be maintained for each curb drain section. Bellies, dips, and non-sloped sections will not be allowed.

Q. City workers who came and cleared the curb drain with pressurized water, told the homeowners on Avondale that this was not the only place where this had happened. In how many locations was there freezing of curb drains?
A: 4

Q.  What could be done to prevent the freezing? Are there warming devices (similar to those people put on roofs to prevent ice dams) that could be installed to correct this problem.
A: See response below.

Q.  The frost line in Michigan is much lower than 1.5 -2 feet. Why were the curb drains not installed deeper--ie, at 42+ inches? 
A:  (Answer both questions)
Questions have been raised regarding the burial of the sump discharge lines at 24-inches deep, and whether this is indicative of a systemic defect in the City’s FDD program.The City’s 24” burial depth (minimum) standard is based on the following requirements and assumptions:

a) The sump discharge lines in the ROW and on private property is required to be constructed with a positive slope meeting the project specifications and the building code based on the size of the pipe.  Each construction installation has been verified and approved by Planning & Development Services.

b) With the required slope, the pipes will not have standing water in them.

c) Sump pump discharge water is typically “warm” at about 55 degrees and will not have time to cool down and freeze in the sump lead or curb drain if positive slope is present. 

d) The exiting storm sewer infrastructure that the curb drains connect to is often shallower than frost depth, making deeper curb drains infeasible.

These requirements and resulting conditions promote effective functioning of the sump discharge line and curb drain, even under extreme cold conditions like those experienced last winter. The specifications themselves are not indicative of any systematic defect in the City’s system.

It is possible that in some cases, such as the houses along Avondale that the sump leads may have “dips” or flat sections in them where the water could collect and cool.  When it was pushed downstream with the next pumping cycle it became susceptible to freezing in the curb drain due to the “icicle” effect.  If such sump discharge line and curb drain collector line dips exist, they do not meet the City’s specifications.

The City plans to investigate the reported cases of pipe freezing and identify any necessary corrective work.