Approved Facility Types

Untitled Document Exhibit 2-1: Stormwater Management Facility Application Table

Stormwater Management Facility Type 

Credit Given with Associated Design Approach
Pollution Reduction 
Flow Control
Eco-roof & roof garden Simplified Simplified NA
Pervious pavement Simplified Simplified Simplified/Presumptive (4)
Contained planter Simplified Simplified NA
Tree credit Simplified Simplified NA
Infiltration Stormwater planter Simplified (1) Simplified Presumptive
Filtration Stormwater planter Simplified (1) Simplified NA
Swales < 15,000 sq-ft impervious area Simplified (1) NA Presumptive
Swales > 15,000 sq-ft impervious area Presumptive NA Presumptive
Level Spreader Presumptive (7) Presumptive (7)  Presumptive (7)
Vegetated filter strip Simplified NA Simplified (5)
Infiltration Rain Garden Simplified (1) Simplified Presumptive
Filtration Rain Garden Simplified (1) Simplified NA
Sand filter Simplified (1) Simplified Presumptive
Wet pond Presumptive NA NA
Extended wet detention pond Presumptive Presumptive NA
Dry detention pond Presumptive (3) Presumptive NA
Treatment wetland Presumptive Presumptive NA
Manufactured treatment technology Performance NA NA
Structural detention facility NA Presumptive NA
Spill control manhole Presumptive (2) NA NA
Soakage trench NA (6) Presumptive Presumptive
Infiltration sump NA Presumptive Presumptive
Drywell NA Presumptive Presumptive

Exhibit 2-1 Notes:     
(1) The Presumptive Approach may be used to downsize these Simplified Approach facilities.
(2) Spill control manholes receive credit for oil removal only; additional pollution reduction facilities will be required to meet basic water quality management.
(3) Vegetated or grassy swales must be integrated into the bottom of dry detention ponds to receive pollution reduction credit.
(4) Pervious pavements in NRCS soil types A or B meet destination requirements when designed using the SIM Form.
(5) Vegetated filter strips designed using the SIM Form may be used for destination for some small projects as outlined in Chapter 2 of the Stormwater Management Manual.
(6) Soakage trenches, having a minimum 18-inch layer of sand for filtration installed below the soakage trench and designed per "Soakage Trench" facility design requirements, may meet pollution reduction requirements.
(7) Level spreaders must include dedicated filtration buffer in the design for management credit.