For example, if you are attempting the stormwater credits SSc6.1 or SSc6.2 in the current project and have chosen to recalculate them for compliance with SSc9, you will need to calculate the stormwater rate and quantity for pre-development conditions (same existing conditions as for credits SSc6.1 and SSc6.2), as well as the stormwater rate and quantity for post-development of the site master plan. Essentially, these calculations must be run twice, once for the current design, to earn SSc6.1 or SSc6.2 and again for the site master plan, to earn SSc9.  When calculating for the site master plan, the pre-development peak discharge rate and quantity are calculated as they would be prior to any development.