As previously noted in our September posts, PA DEP has convened a BMP Manual Revision Committee. In their notification to attendees, they noted that

… recommended updates may include edits to existing portions, complete omissions, or additions of new material.  All changes much be justified through acceptable principles of engineering or science.  If unable, to do so, subgroups may bring new ideas before the bigger committee for consideration and feedback.

Following is PA DEPs statement on the focus of this  Sub-Group, as presented at the first Committee Meeting:

Redevelopment is encouraged to limit green field development.  However, there are also requirements in place to make up for past sins with redevelopment (i.e. 20% meadow, etc.)

• Are there other ideas besides the 20% meadow criteria?   Should there be less stringent criteria for small redevelopment sites?  Should there be more stringent criteria for large projects?  Should building additions/ expansions be included in redevelopment?
• Should the 20% rule only kick in when there are no existing SWM facilities?   (i.e.  no peak rate controls)
• Should anything extra be needed if the % impervious is reduced by 20% or more?
• How should redevelopment be applied to highway projects that propose widening/ adding a couple lanes?  (see Subgroup Topic  H)

Contaminated sites can become quite complex.  DEP has written some guidance aimed at specifically addressing issues with contaminated sites during construction.

• Knowing that brownfields redevelopment is often proposed as retail, office or other high density use, what recommendations does the group have for PCSM for a contaminated site (i.e. redevelopment) that may have conflicts with infiltration?
• How do we factor in a special protection watershed or an impaired receiving stream?

Big Box Retail is commonly incorporated into redevelopment projects.   These projects often consist of high percentages of impervious cover which leads to issues with SWM particularly when volume control (such as infiltration) is limited.

• What recommendations does the subgroup  have for big box development, whether redevelopment or not?   The group may read the following document for background info.  LID for Big Box Retailers. www.lowimpactdevelopment.org/bigbox/

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