I have never heard of on-site Tc measurements, except for a specific hydrology study. One of the challenges is that suitable test conditions (i.e. water flow) cannot be readily reproduced. As long as the stormwater system is built in accordance with the plan, the designed Tc values continue to be used.

Peter Smart
HydroCAD Software
www.hydrocad.net

i don't think anybody does it, certainly nobody is charging for it. i have booked out the door on one nearby project i was particularly interested in during high-intensity short-duration storm to watch the water and then check out the storm from weather underground time-interval collection. to test a system i would be most interested in seeing how a 10-yr and 25-yr storm play out to know i'm never going to get a call. but there is a reason they call those storms "10-yr events"

This was actually a client's request! My thoughts were exactly the same as the both mentioned above. Thank you.

The closest I've seen is to observe system behavior and compare it to the design. But this would require extensive instrumentation to measure rainfall, flow rate, and WSE, probably at multiple points in the system. The time and cost would be it prohibitive except for academic studies.

Peter Smart
HydroCAD Software
www.hydrocad.net