Seal of Dane County County of Dane
Dane County Land & Water Resources Department

Framed Inlet Protection Guidance

Erosion control plans will now be reviewed for inclusion of framed inlet protection in all curb inlets. Field inlets may be protected with other approved methods. Framed inlet protection has been shown to be more effective and require less maintenance than Type-D inlet protection.

Framed inlet protection must meet the following specifications:

  1. All ASTM Standard D8057-17 requirements, including: 
    • Bypass overflow that meets or exceeds inlet design flow
    • Frame and bag strong enough to handle full sediment load
  2.  No part of inlet protection projecting above the grate (e.g., bag fabric)
  3. For combination inlets, capture of runoff entering both grate and curb opening
  4. “Dual fabric” filter bag, with nonwoven bottom and woven top

There may be sites where Type-D inlet protection is an appropriate substitute for framed inlet protection. These will be evaluated on a case-by-case basis for approval.

Framed Inlet Protection Diagrams