Changes

*Waterproof containment can be created using a plastic membrane/liner (HDPE or EPDM are common materials).

*Waterproof containment can be created using a plastic membrane/liner (HDPE or EPDM are common materials).

**When the membrane is being used directly in the ground, punctures from stones can be prevented by compacting a layer sand (30  - 50 mm) over the soil prior to installing the membrane.  

**When the membrane is being used directly in the ground, punctures from stones can be prevented by compacting a layer sand (30  - 50 mm) over the soil prior to installing the membrane.  

**Similarly, a 50 mm sand layer will protect the membrane from the clear stone being used for drainage inside the BMP.   

**Similarly, a 50 mm sand layer should be applied on top of the membrane to protect it from the clear stone being used for drainage inside the BMP.   

*Some designs include a concrete cell to prevent infiltration. The longevity of this type of construction may be improved with a coating of liquid waterproofing compound.

*Some designs include a concrete cell to prevent infiltration. The longevity of this type of construction may be improved with a coating of liquid waterproofing compound.