I’m working on a Project in Portugal, which consists in a 13.400m2 site, with 6000m2 rooftop (harvests rain), 2500m2 green roof, 2735m2 of gardens, 306 m2 of planters and 1840m2 of impermeable pavements. First of all I am considering the use a hydrosystem filter to remove the 80%SST from the runoff, and so I must determine the flow rate that my drainage areas are producing. However I am not sure which model to use in order to determine this flow rate, since the Rational Method asks for a rainfall intensity and the NRSCS model asks for a Precipitation, which in fact will be equal to the 90% of the average annual rainfall (1’’, 0.75’’ or 0.5’’). So, if i use an intensity, will the 2year 24h event allow to treat the 90% of the average annual rainfall? I’m quite confused in this. One other question relies on the following. I’m collecting from a 6000m2 rooftop to a 125m3 tank which will only supply WC’s and irrigation, does this rain water filling the tank need to respect the 80% SST removal, once it is not directly discharged in the draining system? I was only considering treating the First Flush and the overflow of the tank..is it suitable for credit compliance? And one more thing, the rainfall that hit the garden area is considered as 100% treated?