Folks,
Last night we got into a discussion to try to visualize how big the volumes are that Murat was coming up with for storage in his "scale of improvements" discussion. I gave an answer to the volume in Michigan Stadium that did not make much sense, so I though I would clarify (it was late, and I must have been getting tired). For reference, Murat was coming up with volumes that were in the range of 9 to 12 million gallons (MG). If you assume that Michigan Stadium was a rectangle with dimensions of 300 feet by 500 feet and was 100 feet tall, that would be 112.2 MG. For comparison purposes, a 10 MG storage tank that was 20 feet deep would be a square with an edge length of 260 feet. You can recreate these volumes yourself by multiplying the dimension out and using 7.48 gallons per cubic feet. We thought that these examples would help you visualize the size of the storage tanks we are talking about.
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During public comment, there was a comment made that I thought might be misleading and that I should address with the CAC.
The comment was made regarding the water conservation idea, with the inference that we have somehow refused to examine this idea further. It is important for me that you understand that we will examine and each idea and alternative. We do not want to be dismissive of any idea, and want to encourage all of you and the members of the public to feel free to offer any idea, no matter how "zany" it might seem (to use a concept from last night). I promise you that we will not judge you for the idea, we will not think any worse of you if the idea turns out to not be effective, and we will not be dismissive of ideas. To do those things would defeat the whole purpose of what we are trying to accomplish and why we are engaging you and the public.
Some ideas will be examined in greater details than others. Some items may become real obvious right away that they do not merit much effort to examine, and others may take a more detailed evaluation to look at. Our goal is to gain concurrence from you on how far to go and when to stop, like we have on many other items, like the legal issue, the WWTP capacity, how to look at climate change, the public disclosure of Basecamp, and the use of "scenario B" to do the first loop on alternatives. I would hope that you would see the pattern for how we are operating and that we have built up some confidence with you that we are dedicated to this process.
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With all that being said, I will elaborate a little further specifically on the water conservation idea. Now that the model is established, and we are looking at alternatives, it is the appropriate time to evaluate how water conservation measures might help towards solving the problems. If the CAC feels that this is an important item to understand, we can put reductions in water use from water conservation in the model and see how that affects the system.
In my discussions with Frank Burdick and others on this topic, I indicated that we would look at this in more detail when we got to the alternative, and I also indicated my concerns on both a) the ability of that idea to address system capacity issues, and b) the acceptability of this idea to the general public. As representative of the public, item b is up to you to weight in on. The idea would involve a mandatory program throughout the City of retrofitting faucets, fixtures and other equipment to low flow devices to reduce water use.
I would like to illustrate to you the technical reasons why I have concerns about the ability of this solution to address the capacity issues. Recall that last night Murat presented that the base flow at the WWTP was about 29.7 cfs. Typically about 50-60% of this flow is from the use of water and subsequent discharge to the sewer system, and the rest is from ground water infiltration or other constant leaks into the sanitary sewers. So let's assume that about 18 cfs is discharged to the sewer from water use. There are a variety of sources regarding how effective water conservation measures may be, but let's assume that a comprehensive program in Ann Arbor could cut the water demand by half, which I would think would be quite aggressive. That would reduce the flow reaching the sanitary sewer by 9 cfs.
Recall that last night, Murat's presentation showed that "scenario B" had a peak flow about 120.9 cfs. This means that aggressive water conservation would reduce the peak flow in this scenario by 9 cfs, or about 7%. It is pretty clear from these values, that even an aggressive water conservation strategy is unlikely to solely address system problems.
However, aggressive water conservation could be one component of a multi-pronged approach to tackle the issue. Such conservation measures would also result in cost reductions in the operation of the City's water facilities, which would also be beneficial. Clearly, there are a lot of moving parts, and we do not want to be dismissive of the idea without examining it, if the CAC thinks that such an aggressive water conservation strategy warrants further investigation.
Murat and I could see what we can do in the alternatives evaluation to illustrate the impact that this idea may have on the alternatives. It would be good to hear your thoughts on this topic before doing so. I don't want to investigate it further, if the CAC does not think that it would be a palatable idea for the public.
Take care,
Robert
Comments
Robert Czachorski on 16 May, 2014:
Kathy Boris on 18 May, 2014:
Michelle Lovasz on 19 May, 2014:
Judy Hanway on 20 May, 2014: