Summary of horizontal and vertical setback distances
Required and recommended minimum vertical and horizontal separation distances. This represents the minimum distance from the infiltration practice to the structure of concern. If the structure is above-ground, the distance is measured from the edge of the BMP to the structure. If the structure is underground, the vertical separation distance represents the distance from the point of infiltration through the bottom of the system to the structure, while the horizontal separation (often called setback) distance is the shortest distance from the edge of the system to the structure.
Link to this table
| Structure | Distance (feet) | Requirement or recommendation | Note(s) | |
|---|---|---|---|---|
| Vertical | Saturated soil | 3 | Requirement1 | |
| Bedrock | 3 | Requirement1 | ||
| Horizontal | Public supply well | 100 for sensitive wells; 50 for others | Requirement | |
| Building/structure/property line2 | 10 | Recommended | ||
| Surface water | none unless local requirements exist | If nearby stream is impaired for chloride, see [1] | ||
| Septic system | 35 | Recommended | ||
| Contaminated soil/groundwater | No specific distance. Infiltration must not mobilize contaminants. | |||
| Slope | 200 | Recommended | from toe of slope >= 20% | |
| Karst | 1000 up-gradient 100 down-gradient | Requirement1 | Active karst | |
1 Required under the Construction Stormwater General Permit
2 Minimum with slopes directed away from the building