Artificial Turf- Runoff Calculation

[yanthi]

My client wants to install artificial turf by eliminating existing natural grass. I was requested to calculate and proove new development will not increase the runoff from the site.
Turf has a impermeable bed with a perforated treches connected to a catch basin.
Please help if some one has experience in this cal.
Thanks a lot!

 

[psmart]

If you're capturing all the rainfall in the turf system, there may be no surface runoff. In this case, the bed will receive all the rainfall, so a high CN value (98) is appropriate for the rainfall entering the bed.

Estimating the Tc is more complex. This will depend on the travel time through the turf, bed, and trench system. Depending on the exact design, you may be able to model this as a sub-surface "pond".


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[psmart]

Since your system is sealed, we know that the runoff volume from your turf system will be greater than natural grass, which allows some degree of infiltration.

The peak flow will depend on how quickly this volume is released. If you have enough storage available in the base, you can control the peak discharge by deliberately restricting the outlet. In effect, the sub-surface storage becomes a detention pond.

Of course, this will effect the peak timing, which will effect how your discharge combines with adjacent flows to the same drainage system.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[chicopee]

I use to work in research for a company that manufactured foam backing for Astroturf. The type of foam was closed cell PVC which allowed minimal moisture absorption, therefore, assume rainfall as 100% runoff if foam backing is still closed cell. Also talk to the suppliers about your concern as development of artificial grass may have change since the early 70's.

 

[saruman26]

100% runoff (CN=98 or Rational C=0.95), with a Tc based upon the travel time through the discharge pipes to the detention bed.

And don't, don't, don't use the area under the field as the detention facility. This may cause the field to float during rainfall events. You want the facility to quickly and effectively drain to another area for stormwater control.

 

[optioneer]

I have worked on some projects where earth tubes are placed beneath the sports pitches. therefore it seems to make sense to put stone over the pipes and under the sports pitch to save excavation, cost and improve efficiency of earth tubes heat recovery system! Any comments??