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Applications and Limitations While vegetated roofs can be installed on slopes up to 40 degrees,slopes between 5 and 20 degrees (1:12 and 5:12)are most suitable and can provide natural drainage by gravity. Roofs with slopes greater than 10 degrees (2:12)require an analysis of engin- eered slope stability. Vegetated roofs are not included in the lists referenced under.1-2.5.5 Minimum Require- ment#5: On-site Stormwater Management(p.55). However, they are an option available to project designers who want to use other methods to meet the LID Performance Stand- ard option of I-2.5.5 Minimum Requirement#5: On-site Stormwater Management(p.55). Design Criteria The reader is directed to the LID Technical Guidance Manual for Puget Sound(2012), fora more detailed description of the components of and design criteria for vegetated roofs. It also includes references to other sources of information and design guidance. Note that the LID Technical Guidance Manual for Puget Sound(2012)is for additional informational purposes only.You must follow the guidance within this manual if there are any discrepancies between this manual and the LID Technical Guidance Manual for Puget Sound(2012). Runoff Model Representation See Appendix III-C:Washington State Department of Ecology Low Impact Development Flow Modeling Guidance (p.587)for a summary of how vegetated roofs may be entered into the approved continuous runoff models. BMP T5.18: Reverse Slope Sidewalks Purpose and Definition Reverse slope sidewalks are sloped to drain away from the road and onto adjacent vegetated areas. Design Criteria • Greater than 10 feet of vegetated surface downslope that is not directly connected into the storm drainage system. . Vegetated area receiving flow from sidewalk must be native soil or meet guidelines in BMP T5.13: Post-Construction Soil Quality and Depth (p.911). 2014 Stormwater Management Manual for Western Washington Volume V-Chapter 5-Page 937