Decision process for selecting liners
Design process for selecting the appropriate liner level.
Link to this table
| Condition | Design level | Note |
|---|---|---|
| Filtration BMP with less than 3 feet of separation to seasonal saturated soil or bedrock | 1 | Required under the Construction Stormwater permit |
| BMP in confirmed potential stormwater hotspot with high or very high groundwater pollution potential | 1 | Applies to all post-construction BMPs. See section on Potential stormwater hotspots for more information |
| Constructed ponds with less than 3 feet separation from seasonally high water table in a potential hotspot | 1 | |
| Constructed wet ponds underlain by soils with an infiltration rate of 0.3 inches per hour or greater (HSG A or B soils)(see [1] or [2]) | 1 | To maintain a permanent pool |
| Karst terrain with high or very high groundwater pollution potential | 1 | See section on karst for more information |
| Prevent groundwater intrusion into a BMP requiring aerobic conditions, such as iron-enhanced media | 1 | |
| Maintain permanent pool in constructed ponds or constructed wetlands in areas underlain by geologic material that is fractured or has a high infiltration rate | 2 | |
| Separation distance from a BMP cannot be achieved | 2 | |
| Separate tree BMP from road, parking lot, sidewalk or adjacent walls or building foundation | 2 | To prevent tree root intrusion. See link |