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may be met either by using a prescribed list approach, or by meeting the LID Performance Standard. Both of these approaches are explained in detail
in 2012 SWMMWW Volume I, Chapter 2, Section 2.5.5 – Minimum Requirement #5: On-site Stormwater Management, pages 2-28 to 2-32.

Rain Gardens are part of List #1, the prescribed list of BMPs in the SWMMWW, which can be used to meet Minimum Requirement #5. Rain Gardens
are in the second option on List #1 to address runoff from Roofs and Other Hard Surfaces. If Full Dispersion (BMP T5.30) or Downspout Full
Infiltration (BMP T5.10A) options are feasible, then those BMPs must be used instead of rain gardens.

2012 SWMMW Reference:
• Volume I, Section 2.5.5 Minimum Requirement #5: On-Site Stormwater Management, pages 2-28 to 2-32.

4. ARE THERE LOCATIONS WHERE A RAIN GARDEN IS “INFEASIBLE” FOR MINIMUM REQUIREMENT #5?

Ecology has a list of criteria for when a rain garden does not need to be considered to meet Minimum Requirement #5. These are called “infeasibility
criteria”. These “infeasibilty criteria” are separate from the “Where to Locate a Rain Garden” and "Where Not to Locate a Rain Garden” guidance
discussed in the PLAN section of the Rain Garden Handbook. The infeasibility criteria for Rain Gardens used to meet Minimum Requirement #5 are
the same as the infeasibility criteria for Bioretention. If the Rain Garden is deemed infeasibile according to this criteria, then the project does not
need to use a Rain Garden and can use the next BMP on List #1.

2012 SWMMWW Reference:
• Volume V, Section 7.4 BMPs for Infiltration and Bioretention Treatment, BMP T7.30: Bioretention Cells, Swales and Planter Boxes,

• Infeasibility Criteria, pages 7-7 to 7-9
• Other Site Suitability Factors, pages 7-9 to 7-10

5. WHAT TYPES OF SITE ANALYSES ARE REQUIRED FOR RAIN GARDENS USED TO HELP MEET MINIMUM REQUIREMENT #5?

Rain Gardens used to meet Minimum Requirement #5 must meet Site Procedures and Design Guidance that are more extensive than those
described in this Rain Garden Handbook. The 2012 SWMMWW outlines Ecology’s recommended testing criteria, but your City or County may have
more specific requirements and other testing procedures.

2012 SWMMWW References:
• Volume I, Chapter 3.1 Stormwater Site Plans: Step-By-Step, pages 3-1 to 3-16.

• Volume III, Section 3.4 Stormwater-related Site Procedures and Design Guidance for Bioretention and Permeable Pavement, pages 3-103 to 3-106.
• Volume III, Section 3.3.6 Saturated Hydraulic Conductivity – Guidelines and Criteria, pages 3-75 to 3-81 (Note: The text concerning correction
factors does not apply to rain garden designs.)