Hi all,

We have a new construction project that is to build 30 ha factory, however the owner decided only to pursue LEED certification for the office building site, a small portion of the factory site which only has +/- 9000 m2 (building area to LEED site area ratio is 43%).

We decided to calculate the pre- and post-development site runoff only at the LEED office building site, not the entire project, since the LEED project boundary includes the office building site area only.

And the result is that the post-development site runoff is higher than the pre-dev, so we should opted the Stream Channel Protection right?

In this factory site, an underground drainage system are already built. This drainage will lead the stormwater from roofs and hardscapes (internal roads, parking) into an artificial retention pond located outside of the site project which also owned by the same owner of this project. So, the stormwater from the LEED site area will also flow there. No water will flow directly into public drainage system.

For Stream Channel Protection, we have an idea to install an underground tank that will collect stormwater from office building's roof and LEED site area's hardscape (road), and later be used or infiltrate on LEED site area (landscaping). Is this stormwater management plan can be enough for the Stream Channel Protection? Besides this description, what other aspects do we have to input to the stormwater management plan?

And in the leedonline form, it indicates that calculation of the "Critical capacity values for receiving streams demonstrating that waterways can accommodate the runoff values" should be included in the plan. Do you have any ideas on how to measure this? Thanks