← Back to the list of projects

City of Ann Arbor SSWWEP - Citizens Advisory Committee Coordination — City of Ann Arbor

← Back to messages

2.25 -C- What about storage somewhere downstream, closer to the Treatment Plant?

Posted by Lori Byron on 21 Dec, 2013
Category: Category 2 - about potential recommendations

Frank Burdick’s Log Number: N/A
Submitted by: via email
Category (1,2,3): 2
Status: Closed
Estimated date to address: N/A

[Via email to Robert Czachorski] Q. [What about storage] somewhere downstream, closer to the Treatment
Plant, the idea being to avoid spills/EPA fines...The resolution of upstream flow capacity was quite completely covered in the 1997 report, showing pipes in red needing upsizing, and pipes in blue considered satisfactory. These pipes were shown regionally, within the City. In the 2001 Report, Sanitary storage was ranked at 100% in several regions, and 95% in others (losing out to Disconnects). Your mail reiterates that probable solutions will be regional (or localized). I completely agree with this because it means we could spare much of the grandfathered residences and possibly new ones from what I consider a nightmare of new problems associated with pumps. And, at a rate of 600-700 disconnects per year (including homes with very low footing flow), it would take over 30 years before running out of Mitigation possibilities. Meanwhile we are supplying Sanitary service in alarming numbers within and outside of the City with no plan for increased Treatment Capacity (and $145,000,000 to just modernize but stay even in capacity?)  The City/City Council selected the Disconnect process because there were more 100% areas than 95% areas; the ranking system being arbitrary and not scientific. (some current Councilpersons  like Consultants because they can choose to ignore their conclusions and recommendations. They have that right, but they are elected by us. I wonder how many of them or City Staff have sump pumps and are in a position to judge?

[OHM Advisors] A. Thanks for the feedback. I think a lot of these items will come up and be examined during the alternative evaluation. We will be preparing a similar map as the 2001 study color-coding the pipes by capacity available, with the impacts of the FDDs done to date reflected on the map.  That should bring a lot of things into focus.

With respect to storage, if we find that it is needed, it will be a balancing act on where to locate it.  Pushing it downstream closer to the plant will mean that added pipe capacity in the form of relief sewers are needed to get the flows from the neighborhood where the flow is generated to the storage tank, and that adds cost to the storage as an alternative. If you push it upstream closer to the source, you run into limited land availability. One option that might be a good idea to examine is the notion of “linear storage”, whereby flow is stored in an oversized pipe. This might allow us to get the storage closer to the source.  Linear storage has its own disadvantages that we will have to review with the CAC and the City. The evaluation of all of this is really going to depend on the outcome from the hydraulic evaluation, and input from the public. 
 
One item that I feel is necessary to set the record straight on is your comment that "The City/City Council selected the Disconnect process because there were more 100% areas than 95% areas; the ranking system being arbitrary and not scientific.” As I understand the history, that is not an accurate depiction of how the decision was made.  It is my understanding that the City formed an SSO task force and conducted several public meetings, where the citizens on the task force examined the options and decided that they would rather disconnect FDDs than place storage tanks in the parks, woodlands and wetlands that were available for tank sites.  The public made this recommendation to Council, and the City implemented the recommendation. It was a very similar process to the one being followed now.

Comments

Patricia Marten on 13 Feb, 2014:

After funding the 1997 study, did the city add any storage and increase pipe size due to results, of that?

Joe Conen on 13 Feb, 2014:

To give a sense of how powerful linear storage can be, a 36 inch pipe can store about 50 gallons per foot more than an 8 inch pipe.
For a 4 gallon per minute peak footing drain flow for a 1 hour peak, the volume is 240 gallons.
So a 20 foot section of this larger pipe would be able to store more than 4 times the hourly peak flow from an "average" footing drain.
Many ways to fiddle with the numbers, pipe sizes, etc. But this is a reasonable example.
Joe

Frank Burdick on 13 Feb, 2014:

Regarding the statement:  As I understand the history, that is not an accurate depiction of how the decision was made.  It is my understanding that the City formed an SSO task force and conducted several public meetings,

Who is making this statement? Who is the attributable City Source?

Jim Osborn on 13 Feb, 2014:

To show how much storage will be needed per prolific footing drain household, An 8" pipe has a cross sections area of 50 Sq inches and a 36 inch diameter pipe has a cross sectional area of 1017 inch, a  20.25 difference, not 50. We would need a 57 inch diameter pipe to be 50 times as large.

If we were to add a 36 inch pipe, which is 20 times as large, a 20 ft section could hold the flow (@ 4 GPM) for a bit over 4 hours. But this would not help those at the bottom of the hill, as the water will fill up that part of the pipe and back up those homes. What if it rained longer and pumps kept pumping for longer than 4 hours? It would be very hard to place every pipe perfectly to prevent low spots that would adversely affect some unfortunate home.

Joe Conen on 13 Feb, 2014:

Jim,
You need to re-read what I wrote.
I did not say a 36 inch pipe was 50 times as big as an 8 inch pipe or that it held held 50 times as much. I said it held about 50 gallons per linear foot more than the 8 inch pipe.  You take a very aggressive tone in these comments, and it is not appreciated.
Joe

Jim Osborn on 14 Feb, 2014:

I'm sorry Joe, I was mistaken, you did say 50 gal, not 50 times. I misread "50 gallons per foot more" as "50 gallons per foot times".

I do not intend to take an "aggressive tone" in these threads, and I'm sorry that you interpreted them as such. I was just listing the facts as to why I believe that temporally storing sewage near a home that is at the bottom of a hill and already is experiencing issues will not be a robust solution. I then listed why.

On the down side, the portion of the pipes nearest the lowest home will fill up first, flooding that home.

But upon reflection, if this solution were very inexpensive, and solved the problem most of the time, then I'd support it. We need costing information.

What is the cost to place a 20 foot piece of pipe in front of a home, or down a block, vs other methods such as FDDs? Can each 40 or 50 ft section, to cover both homes on both sides of the street, be done for a similar cost of two FDDs? In 2011 sewer pipe was replaced along Collingwood in Ann Arbor. How much did that cost per foot? A nd that was just standard size pipe.

Joe Conen on 14 Feb, 2014:

So Jim, I tried to make clear the 36 inch pipe was an example ("Many ways to fiddle with the numbers, pipe sizes, etc. But this is a reasonable example.")
My sense of your comment was of dismissiveness - no attempt to indicate that larger pipe might be needed. just a tone that, "This won't work."  Even now the statement that storage, "will not be a robust solution" implies that this is written off from further consideration.

We need to explore how to make solutions work. 

I agree that installation cost is an issue, but it is not the only driving issue to me. Sanitary backups are a community problem, and a community solution is warranted. A solution that imposes uneven costs and burdens on individual homeowners does not describe a community solution, to me. So if we want to continue FDD, this needs to be fixed.

Also, there are inherent advantages in "passive" approaches, especially reliability, no dependence on power, lower maintenance costs, etc.
The original FDD ordinance did not adequately address costs. No backups were provided although they were implied to be necessary by the homeowner package. Maintenance costs became a homeowner issue, and were then (incorrectly)  factored out of the cost for that option.
This is not to say that future FDDs are off the table, but my view is that we need to explore options that minimize disparate impacts on homeowners and then judge them against ways to continue FDD in a less heavy-handed way.
Bottom line, as a taxpayer and a homeowner, I am concerned about cost, but it is worth it to me to pay my share in delivering a robust solution that is fair to homeowners.
Joe

Michelle Lovasz on 15 Feb, 2014:

I am interested in the answer to Patricia's question:  (pasting) After funding the 1997 study, did the city add any storage and increase pipe size due to results, of that?

Michelle Lovasz on 15 Feb, 2014:

Ann Arbor is now, as it always has been, growing.  More buildings, more parking lots, more people, both visiting and residing.  We like our old buildings, our brick road sections, and all the markers of our history.  Except piping.  It has to accommodate the flow.  It can be separated into sanitary or storm, but at some point it's too interactive to isolate one aspect into, say, "sanitary sewage wet weather event".  I agree with Joe it is a community issue and the burden of accommodating the community's needs does need to be a community concern, not an individual homeowner's.  That said, I think individual homeowners should be held to standards that uphold the community's needs, not unlike "keep your sidewalk shoveled or you'll be fined". 

Judy Hanway on 16 Feb, 2014:

I agree that the city is growing and this should be a concern for us. The more buildings, the more sewage in the same pipes. We need to find out what work has been done (and where) as to increased sewer pipe size, replacement, etc since 1998.

Lori Byron on 27 Feb, 2014:

Patricia, 

Earlier in the thread, you asked this question, "After funding the 1997 study, did the city add any storage and increase pipe size due to results, of that?"

Did you mean the 2001 SSO Study? If so, the response is:

[CITY] A.  No.  The need for the Swift Run relief sewer project which was completed in 2008-2009 was identified prior to the 2001 SSO study, however it was briefly mentioned in the 2001 SSO report.

Michelle Lovasz on 28 Feb, 2014:

Ok, thanks Lori.  Ouch. 

Judy, Mr Eaton was with us at Panera last night.  He also seemed to be of the opinion that "growth" is an issue.  We've got facts, data, etc that counter the validity of that concern, namely, population growth in Ann Arbor as projected by (a very valid acronaymed group, Robert has the name) will be less than 10% in the next 30 years. 

However wrong the gut feeling might be, up against facts, it does have some critical mass amongst us which is worth exploring more fully.  And the questions may have been answered, here, there, but I think the "gut feelings" are still prevalent enough that it warrants a condensing of the information, so that it is more digestible and we can find if there remain any unanswered significant questions. 

I think the base issue here is our concern about capacity issues and physically where they are.  Many questions have been asked from many different directions regarding:

Is our system enough for now?
--storm pipes? (overall and isolated by neighborhood)
--sanitary pipes? (overall and isolated by neighborhood)
--treatment plant?

The maps are coming...

Is our system enough to accommodate the future?
--increased need for storm  (in number or intensity of wet weather events)
--increase need for sanitary (in population growth, or visitors, etc)

Patricia Marten on 28 Feb, 2014:

Lori,
I was referring to the 1997 Black and Veatch report (not the SSO report).  Which Frank asked about in the question, at the top of this thread.  We will see soon, in the new maps-- what is needed.  But I wanted to know if, after requesting and paying for a study, the city increased pipe sizes as suggested in the 1997 report.
Thanks,

Judy Hanway on 28 Feb, 2014:

Michelle,

Regarding the projected population growth in Ann Arbor, I'm wondering if the firm you mentioned took into consideration the growth of the surrounding townships, some of whom send their sewage to Ann Arbor to treat. 

I'm waiting to hear more about the WWTP capacity, the answer to Pat's question about the City's response to the BLack & Veatch report, as well as the information Murat and others on the Project Team are assembling.

Judy

Lori Byron on 12 Mar, 2014:

[CITY]

A. The 1997 Black & Veatch was a stormwater master plan and not related to the sanitary sewer system.

Michelle Lovasz on 12 Mar, 2014:

Nonetheless the question remains:  "..if...the City increased pipe sizes as suggested in the 1997 report."?  Nick? 

Judy Hanway on 13 Mar, 2014:

Regarding the City's response above:

"[CITY]
A. The 1997 Black & Veatch was a stormwater master plan and not related to the sanitary sewer system."

I think it is very clear that the stormwater capacity is very much related to the sanitary sewer system since some FDDs are connecting to the stormwater drains in the right of way and, in some cases, unable to discharge due to the amount of water pressure in the line during storm events. Also, many FDDs are discharging into the yards and thus ultimately going to the stormwater sewers. 

So the question still is: what "fixes" have been made to the stormwater system since the 1997 B&V report? 

Jim Osborn on 13 Mar, 2014:

I agree, that the two are very related. Unfortunately, our study does not examine this, although I wish it did.

I've wondered that if drainage were solved in some neighborhoods, would the footing then drain a lot less, making FDDs unnecessary?

Michelle Lovasz on 14 Mar, 2014:

Jim I think that wondering has much potential.  In other words, I think you mean that individual homes' footings are collecting stormwater that could be collected elsewhere before it hits the footing of that home.  In some neighborhoods this might be quite efficient, but probably has to be very specific.

Jim I think our study does examine this.  I think they are so related that it matters very much to our study.  Each one of our alternatives thus far involves stormwater management, to avoid it impacting the sewer.

Lori Byron on 24 Apr, 2014:

Here's the response to the question asked earlier in this thread, "Q: After funding the 1997 study, did the city add any storage and increase pipe size due to results, of that?"

A: Many stormwater improvement projects (eg. regional detention, oversized storm sewer pipes for providing detention under roadways, etc.) have occurred since the 1997 B&V study. These project locations are identified on the Citywide Storm System Improvements map located in the website library. [http://www.a2gov.org/Documents/Citywide_Storm_System_Improvements.pdf]

In addition, the project team for the Citywide Stormwater Modeling & Analysis project is performing an analysis of the FDD impacts to the city’s stormwater system.  These findings will be shared with the CAC when completed.    

Michelle Lovasz on 30 Apr, 2014:

Lori, I opened the pdf and it is simply too blurry to read, even with zooming.  Is there a different access to it? 

Lori Byron on 5 May, 2014:

Michelle, 

That's strange; I opened it and could read it clearly after zooming in. I can see about having a larger print made for the CAC meeting next week. 

Michelle Lovasz on 5 May, 2014:

I'm fine with that.  Thanks Lori.