Hi, there has been some previous discussion in this topic, but no definite answer has been given. Example 2 in the ref. guide uses 1" storm, referring to it as 90% of the average rainfall event. However, the credit requirement for SSc 6.1 requires the usage of the 24hr storms. It is quite confusing whether this calculation would meet the requirement, which they give as an example. Can we use the 90% of the annual rainfall events??