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Sewer metering & RDII rainfall

Sewer metering & RDII rainfall

Sewer metering & RDII rainfall

We have been metering sewer lines for about a year. We have tons of flow meter data at 15min intervals. We have rainfall data.
We have analyzed the peak rates vs rainfall and have pretty much determined if it's inflow or infiltration in areas. That all said,
I keep getting asked "what happens when I add in a 2yr rain event?". My initial response is, I have rain data and can find a 1-2yr rainfall
event that has happened in our metering timeframe and can show them the peak flow during that event. But upon further meetings, with the downstream
receiving municipal authority that has the WWTP, they want us to add in areas, CNs, into our flow. I have actual "real" flow from metering.
Isn't adding in RDII curves on top of meters double dipping ???

RE: Sewer metering & RDII rainfall

It doesn't make sense what they are asking. Could they be thinking that your flow data does not show an infiltration event during the 2 year storm and they think you are 'estimating the infiltration' during rain events for the larger events.

Maybe they don't realize that you have flow data that includes actual physical infiltration and that you are not calculating it and adding it to meter readings.

I would think that your data shows little infiltration during the 2 year storm and they think something is wrong. I would expect little infiltration during those events.

But adding in flow based on area / CN would be double counting. It sounds like the borough people are missing something.

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