TR-55 availabe outside US

Hi Javier, did you find an equivalent of TR-55 for Europe?

Thank you in advance!

We're in Canada - here's my question to the USGBC on how to apply TR-55 We have not heard back from USGBC yet.

1. We're in Canada and nobody is aware of an equivalent local standard to TR-55. So our geotechnical engineer tried to apply the TR-55 analysis.

2. Our site is an urban redevelopment, with the existing site a near lot line development, maybe 10-15 percent permeable surface at best. Post development condition does not leave any original soil, and the parking garage underneath the project extends to the lot lines. 

3. The engineer reviewed the USDA TR-55 and made the following comment: "their reference to storage is continuously referred to as a man-made storage facility (in their examples a detention basin) used to control peak discharge from a site. In this sense, I don't know of any storage facilities at the site so storage would be zero. 

In a hydrologic sense, storage is typically within biomass, soil moisture, groundwater, rivers/lakes, oceans and glaciers. The only factors that would apply to this site are biomass, soil moisture and groundwater. I'm not sure how to calculate a storage volume of a biomass, but we could determine storage within the soil based on its infiltration capacity. Based on the TR-55 document, the soils in the upper 2.5 m that are capable of providing water storage would probably be type A (infiltration greater than .3in/hr or 7.6 mm/hr). We would need to confirm infiltration rates before we recommended anything for a design, but for a pre-development calculation this should be enough information to determine your storage volume. Groundwater should be assumed to be at 2.5 m below grade and essentially equal in volume to the soil porosity, likely 15% to 20%; however, groundwater should not be considered as a storage reservoir for site-specific purposes as it stores water on a regional scale and we also haven't completed any groundwater studies at this site yet.  

 A theoretical solution that would not be used in real life would be to multiply the volume of soil currently on site that is not covered by a building or hardscape and is above the water table  x  storage capacity in %. 

Please advise, is this an acceptable way of examining TR-55 water storage capacity for the site for compliance with SSc1?

Hi Jason, hope you're well :).
I'm facing a similar issue with a project that is mostly comprised of hardscape, with likely under 10% permeability, and an existing site mostly consisting of compacted fill (soil group D I think). Did your question end up getting answered? Would an estimated rate of water transmission x soil area to 2.5m below grade be a suitable way to complete the TR-55 section of the Site Assessment credit? Any input is appreciated!