Runoff samples will be collected from 18 collection sites during artificial storms generated by a water truck applying 12,000 gallons of water on the site (1,000 gallons per test segment) over the course of about seven passes.
This amount was chosen due to practical constraints which included applying enough water to provide for flow into the collection vaults without applying too much water that would flush all the pollutants off within the first couple of passes by the water truck.
This amount of water is equivalent to an ~17 hour volume of a 10 year, 24 hour storm intensity. This is also equivalent to ~12 hours of a 24 hour, 100 year storm intensity.
Samples will be analyzed by the City of Yakima Wastewater Treatment Laboratory for stormwater pollutants associated with urban locations including:
Tanker truck making a water dump run, samplers are standing by
Dumping water onto porous concrete
(note no puddles)
Porous concrete & permeable pavers immediately after pass of the tanker truck.