City of Ann Arbor SSWWEP - Citizens Advisory Committee Coordination - Q. 2.104 -C- Will these ultrasonic flow meters will these work to test flow at homes prior to FDD?

Q. 2.104 -C- Will these ultrasonic flow meters will these work to test flow at homes prior to FDD?

Posted by Lori Byron on 21 Feb, 2014
Category: No category

Q. Will these ultrasonic flow meters will these work to test flow at homes prior to FDD?

http://www.grainger.com/category/ultrasonic-flow-meters/process-monitoring/test-instruments/ecatalog/N-be4Z1z0hsiy

[OHM Advisors]

The footing pipes are likely flowing in an open channel flow mode (non-pressurized), which requires the measurement of depth and velocity. (flow = area * velocity, and the depth is used to compute the cross sectional area of the flow). We normally do this in sanitary sewers with a continuous flow meter like this, which makes use of doppler for the velocity, and a pressure transducer for the level:

http://www.isco.com/products/products3.asp?PL=2021010

In fact, this is the model of meter that was used for the metering program last year in the sanitary sewer. I don’t believe that a continuous doppler meter like the Isco meter would work in this application, because it will be difficult to mount the sensor, the probe will interfere with the flow, and the footer flow may not have adequate solids to make a doppler flow measurement (100 ppm solids or so).

A handheld doppler velocity sensor such as the referenced model will have many of these same limitations. It may address the problem of mounting the sensor, but it is not a continuous measurement, and does not measure the depth. So you would have to be at the house making measurements during the peak of a storm event, and you would need a way to estimate the depth to get a flow rate. Even then, it is not clear whether adequate solids would exist in the flow for the doppler to work. (For reference, sanitary sewage is typically 300 ppm solids, and this sensor requires 100 ppm. Footing flow would likely have far less solids than sanitary sewage).

My opinion is that these technologies would not be suitable to measure the footing drain flow prior to FDD. As I have stated before, I do not know of a meter that is capable of providing a continuous, affordable, accurate measurement of a footing drain flow.

Comments

Frank Burdick on 22 Feb, 2014:

Regarding Robert statement: I do not know of a meter that is capable of providing a continuous, affordable, accurate measurement of a footing drain flow.

Me thinks he speaks too soon. There is a design being formulated by members of this group that may be very effective to monitor flow prior to an fdd and certainly can monitor flow after a fdd.

I am requesting that Joe C. post this concept, sketch, product, etc as a seperate issue or question on basecamp. It needs to come from someone other than me so that it is more likely to be considered.

Robert Czachorski on 22 Feb, 2014:

I would welcome the development of a meter that is capable of providing a continuous, affordable, accurate measurement of a footing drain flow prior to FDD. Sometimes in R&D and invention, it takes a new perspective to solve an old problem.

Joe Conen on 22 Feb, 2014:

Under the umbrella of "possible doesn't always mean practical," I offer the attached crude conceptual sketches of a way to measure footing flow prior to conducting a disconnect. There are practical problems with this, since it would essentially be a "custom" installation, and the labor and hardware costs may make this unsuitable for widespread use. Also, this would be potentially disruptive to a homeowner, since this setup would need to remain in place for a monitoring period. As shown, this would be vulnerable to power outages leading to wet basements, although that is probably solvable. With these qualifications in mind, I think that footing drain flow could be measured and recorded before undertaking a FDD, if we decided that it was important to do so.

The system uses a torpedo pump, which is something that can be inserted into the footing drain cleanout. Two sketches are provided, one has a "collection volume" and the other is directly piped though the flow meter. The collection volume may be necessary to smooth out flow so the meter is accurate. For simplicity, flow is shown to be directed to a floor drain; other arrangements are also possible.

Note that flow monitoring in homes that already have a sump pump would be much easier. For neighborhoods where FDD has been partially implemented, it may be valuable to sample these homes if we decided that the benefit of continuing FDD in these areas needs to be better documented.

Joe

Michelle Lovasz on 22 Feb, 2014:

Like.

Robert Czachorski on 23 Feb, 2014:

Very interesting. I like the idea of using a temporary pump to create an opportunity to meter the flow. Perhaps Greg could comment on the feasibility. If I know him, if it’s feasible, he will probably build one and test it at his own house.

I wonder if the pump could be paired with an in-line Venturi meter to keep everything in the pipe.

Frank Burdick on 23 Feb, 2014:

have greg ask joe where to buy all of the components... ie flow meter, torepedo pump, etc... we have already done all of that recon work and can provide the spec sheets etc

Greg Marker on 24 Feb, 2014:

CAC members,

I have been trying to build a sensor to measure footing drain flow from inside a clean out for the last two years. The ultrasonic option could possibly be done (there are multiple different manufacturers of these commonly used sensors), however the tightness of the area it is being deployed would likely prevent its accurate installation. Additionally, It has a high cost per house so it is not a good bang for the buck in my opinion let alone tackling the technical issues of its installation. Sensors can be moved from house to house, however there is a lengthy deployment time and the costs to install and remove remain for each house no matter what. I have tried two logging style sensors to date, one with a leaf wetness sensor, and one with temperature sensor. Neither has been able to accurately correlate footing drain flows ( I have been able to deploy them in cleanouts that are upstream of a pump, therefore able to prove if they are accurately working or not).

My latest idea is trying to use an industrial level sensor that is used to measure volume in containers and turning that signal into something that can be read by a logging device. I have not had the time to continue its development, however do intend to continue that thought to implementation and testing as I have time. This idea will be a new creation of a new product that is not on the market involving manipulating existing equipment (read void warranty) and will require electrical work to modify and connect the two devices.

Reviewing the idea for the torpedo pump system to measure the flow, the torpedo pump and piping would be about $500, the logging device would likely be about $3000 with $1000 in costs to deploy and later collect the equipment that could then be deployed in another house. I fear that at those costs, we maybe should just do the work to disconnect the footing drains.

In my past logging experience of footing drains in Westland Farmington, for every ten that we disconnect, three to five are average flows, two are heavy flows, and two to four are pretty minimal. That may not apply in these areas, only a comparison of previous sump loggers could let us know what it is in our five neighborhoods. I have always thought that if we could identify what flows come from which houses with a logging system that was 10% of the cost of the disconnection, then it would make sense to log the homes in advance of a disconnection and then go after the heavy flows with more money since some of them would not have to be done, leaving more to spend at the homes that are the problem.

Thanks

Greg Marker

Frank Burdick on 24 Feb, 2014:

We have the costs of the proposed pre-test devices. They are less than the amounts listed above. Ask Joe

Frank Burdick on 24 Feb, 2014:

Lori, please include all of the cac on this string

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

Q. 2.104 -C- Will these ultrasonic flow meters will these work to test flow at homes prior to FDD?

Comments