I am not quite sure if the approach discussed in my project team is a viable way to achieve this credit and would like to check back with you. The project is in a dense city location and will be impermeable to 80-90%. There is zero lot line on 2 sides, a zero lot line neighbour on the third side and a basement for most of the site, with the building and open space above. There will be a strip next to the building insite the site limits, 5 metres wide, that is part of an adjacent plaza, has no basement below and will have an almost impermeable surface.
This strip next to the building is the only place where rainwater could be infiltrated. The project team proposed to build a structure below this strip that will infiltrate rainwater and retain any rainwater up to the required percentile that exceeds that infiltration rate. The structure will be covered and not be seen from the surface. It would be designed to retain and infiltrate percentile rain as required for the pursued number of points.
Some questions arise:
- Given that there is a 5 metre wide strip next to the building footprint I assume this project cannot be taken as zero lot line? Is there a definition of “…nearly aligns with the site limits”?
- Is this kind of covered, underground infiltration trench compliant with the requirements “best replicating natural site hydrology”, is this a LID measure?
Thanks for any views, tips and hints.