Port Orange Wastewater Treatment


Collection System Inflow and Infiltration …

leakyPipesJason & City Council, ….
Your memorandum report of I&I is a good start, but really all it is, is a start.  My intent s not to be critical of your report but to have us take this start and complete a report and proper recommendations so that City Council can take the appropriate actions.  As Manager Kisela has mentioned, Miami-Dade had spent well over $100 million dollars without any measurable results towards their I&I problem.  I say had because Miami-Dade has begun to adopt the Best Practices as outlined in the January 2014 Florida Water Resource Journal written by Dr.  Fred Bloetscher.  Many Florida County and municipal water treatment utilities have adopted these Best Practices now.  I had asked you if you had read the article before and you said “no”.
Here is an on-line link to the article.  If you click on a couple of buttons you can make it full screen where it is easier to read.
For City Council members who may not know the industry I&I terms, inflow is rain water getting into the sanitary sewer and infiltration is ground water leaching into the sanitary sewer.  To say that I know a little bit about the Dania Beach inflow abatement project featured in Fred’s article would be an understatement.  I was on the smoke testing crews that smoke tested the entire city.  I opened manholes and did inspections.  I gathered GIS information, did inspection reports and exported data for Dania Beach to integrate into their GIS system.  Locally, I did smoke testing and manhole inspections in Ormond Beach when Fred Costello was mayor.  The manhole inflow dish, which I co-designed, that is featured in the article was the subject of an exhaustive engineering study by Miami-Dade.  Miami-Dade is now purchasing thousands of these dishes and they do work well.  The blue flexible polymer manhole coating that you can see pictured in the article was the result of a product we spun off from a company in Minnesota that I was a part owner in.  I do know a little bit about I&I abatement.
I attached your report and it s a good start.  It is a lot better information than when I first asked about it at the City Council meeting a couple of months ago.  You have identified that Port Orange does have a costly I&I problem which is increasing our operating expenses.  Before City Council should decide to authorize expenditures and go forward with any I&I abatement project, we should have a more detailed report and a complete project plan.  I certainly would like to see you and your team complete the study for the entire Port Orange sewer system and provide a payback and rate of return numbers.  In the Dania Beach study, Fred estimated a two year payback for implementing the “G7” program.  With other cities, like Punta Gorda, the payback is more like 3 to 5 years.  He also estimated an 85% savings or reduction in videotaping sewer pipes and some of the other expenditures that you have in your proposed budget numbers for 2014-2015.  His recommended best practices (now adopted by many water treatment utilities in Florida) is to eliminate the inflow problem which will help isolate the infiltration problem.  This was where Fred was estimating the 85% savings.  At our last Audit and Budget board meeting, you were estimating in excess of $7,000,000.00 per year towards your capital project costs for the next five years.  This totals in excess of $35,000,000.00.  If we can even save half of that, or $17,500,000.00 through proper planning and Best Practices, we need to go that route.  I am not saying we can save that much, but right now, I am sure we could realize a significant savings over the budgeted costs.
You made some assumptions and jumped to some conclusions in your memorandum that I may disagree with.  You conclude that Port Orange has a ground water infiltration problem rather than an inflow problem because you see a “negative” flow in dry months.  I think this was one or your statements or conclusions: ” A negative inflow rate indicates that wastewater is leaving the collection system rather than coming into the system.”  Based upon the little bit of information in your report, I would conclude the opposite.  I would have to see your numbers, but if you are comparing dry month flow to your “base line” flow, it would seem only natural that the dry month flow is less.  From what I can see, your baseline flow for four months includes between 9 and 10 inches of rainfall.  Any month with less rainfall than your baseline would naturally be less or “negative”.  I am not disagreeing with your four month average baseline calculations.  You will just need to also get a zero rainfall baseline to work with and do additional analysis.
Underground sanitary sewer pipes may need to be replaced or lined because of problems.  This report did not include any information on actual breaks and construction costs to repair the breaks.  That would be important information to have before deciding to spend money to replace underground lines.  It would be nice to see a city map with pin points for all of the breaks over the past three years.
I also attached the Excel sheet that you had sent me with your raw Influent Flow.  I was surprised to see negative flow numbers in the report.  I asked you about those flows and you said that it was water flowing backwards through the pumps when the pumps shut-off.  It may seem strange, but to me that indicated some malfunction.  Maybe the pumps were defective or maybe there was a malfunctioning check valve.  If I got the numbers correct, that could mean tens of thousands of gallons being re-pumped every day.  If that were the case, any numbers of flow or peek flow that we would have may be suspect.
I for one am glad that we are looking into the I&I problem here in Port Orange.  The smaller city of Dania Beach, according to Fred, was realizing a savings in excess of $200,000.00 in operating costs after implementing the “G7” program.  We really do need to do more work though before we can make any proper assumptions and come to proper conclusions.  I will be glad to discuss this further with you.
Mark Schaefer
3606 Donna Street
Port Orange, Florida 32129

4 thoughts on “Port Orange Wastewater Treatment

  • June 13, 2014 at 1:46 pm

    Mr. Schaefer
    I too read the I&I report and wrote a short comment about it on another post. I agree it’s a good start but there is more that needs to be done before they start throwing money at it. The data that they have collected is really just indicators of potential problems. Now the real work begins I hope. I’m glad that you mentioned smoke testing I sent an E- Mail to my councilman detailing some of the additional work needed for a more complete study of our sewer gravity systems but I completely forgot about mentioning smoke testing. There have been best business practices and protocols out there for many years for maintaining sewer and water systems. Our city just doesn’t follow them the way they should. That is why we find ourselves suddenly playing catch up.This has frustrated me for years. Council needs to be educated on many parts of utilities operation and maintenance, but it would take way more than 3 minutes at a council meeting.

  • June 13, 2014 at 11:14 pm

    There is a problem with using pump run times. To utilize run times you must calculate in pump curves. Deep wet wells, long pipe runs , obstructions, high force main pressures all reduce pumping capacities greatly. A brand new installation will not even run at the 100% rating in the pump curve. There are times during rain events that force main pressures rise and smaller stations just continuously run without being able to actually pump into the higher pressures in the force mains. They actually run for hours on end with check valves either closed or barely open. This could reduce a pump calculated to run perhaps 250 gpm down to literally nothing during these periods. Meters work great when properly maintained and calibrated. They are a far better measurement tool than pump run times with unknown pump curves and all of the variables mentioned above to also include pump impeller and motor wear as well. What do you think Woody?

    • June 14, 2014 at 9:00 am

      You are absolutely correct. We also have plugged up force mains due to low flow velocity that effects pump performance. We have a problem with force main sizing, too big for normal flows and too small for high flows. That’s a catch 22. You need a minimum of 2.5 ft. per second of continuous flow velocity to keep the force mains clean. These are some of the reasons why I say that the report is just indicators of potential problems at best. They do not consider all of the variables in the report.They still need to be verified with smoke testing, video inspections and manhole inspections. We need a good ongoing proactive inspection and maintenance program for the sewer systems. Meters would be expensive to install and maintain but they would be helpful. Think of the cost to install 120 plus mag meters plus the electrical and telemetry equipment and also calibration costs.

  • June 14, 2014 at 9:37 am

    I don’t think metering at all lift stations is cost effective. Our system is unique in that we serve multiple private systems and communities. They pay sewer charges based on water consumption. They are more than happy to send us their rainfall runoff rather than paying for costly improvements in their communities to rectify the problem. Who in their right mind would make costly improvements if Port Orange is willing to accept them for free ? Why not meter them on the sewer side and when they received the bill for a couple heavy afternoon storms they would find it cheaper to handle their runoff on site rather than pass it on over to Port Orange. A simple comparison of potable water use with sewer flows would perhaps be a better gauge.


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