Reverse Slope Sidewalks

5.4.11 Reverse Slope Sidewalks

5.4.11.1 BMP Description

Reverse slope sidewalks (BMP T5.18 in Volume V, Chapter 11 of the Ecology Manual) are sloped to drain away from the road and onto adjacent vegetated areas.

5.4.11.2 Performance Mechanism

Sheet flow from a sidewalk is directed towards a vegetated strip and away from directly connected impervious surfaces.

5.4.11.3 Application and Limitations

This BMP is applicable for new or replaced sidewalks with adequate vegetated flow path length down-gradient from the sidewalk. It can be used to meet the LID Performance Standard and flow control requirements (Table II-5.15).

Sites where it is not practical to direct sheet flow runoff to the back of sidewalk, like directly onto private property or into a cut slope, are not recommended for reverse slope sidewalks. Evaluate the downstream flow path behind the sidewalk to determine applicability for each specific location.

Table II-5.15. Reverse Slope Sidewalks Applicability.
BMP	MR #5: On-site Stormwater Management		MR #6: Runoff Treatment				MR #7: Flow Control
BMP	List	LID Performance Standard	Basic	Enhanced	Oil Control	Phosphorus	MR #7: Flow Control
Reverse Slope Sidewalks		X					X

5.4.11.4 Design Information

The following design criteria apply to reverse slope sidewalks:

Greater than 10 feet of vegetated surface downslope that is not directly connected into the storm drainage system shall be available to disperse sheet flow runoff from the sidewalk.
Vegetated area receiving flow from a sidewalk shall be native soil or meet the guidelines in BMP T5.13 in Volume V, Chapter 11 of the Ecology Manual.

See the Runoff Model Representation modeling requirements in BMP T5.18 in Volume V, Chapter 11 of the Ecology Manual.

5.4.11.5 Minimum Construction Requirements

Construct similar to a traditional sidewalk, with the sidewalk surface sloping away from the road, directing stormwater runoff evenly onto down-gradient vegetated flow paths.

5.4.11.6 Operations and Maintenance

Maintenance practices of reverse slope sidewalks shall follow those of traditional sidewalks. Additionally, maintenance of the downslope vegetated surface shall be conducted as needed to maintain sheet flow conditions.