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:

The manual should have more information and guidance on Construction Oversight.

• By whom, (credentials of overseer?)
• How often. When are the critical times during construction that oversight is crucial?
• Which BMPs are more critical than others? Should we even mention this?

Short term O&M - Most BMPs that fail, do so relatively quickly due to poor planning, poor construction or poor O&M.

• By whom, (credentials of inspector?)
• How often? - dependent on frequency recommended by manufacturer or other factor.
• For vegetated BMPs, what can the owner expect to do and how often?  (replanting, tilling, aeration, etc.)

Long term O&M and replacement.

• What is the useful life of most BMPs? (by category)  When can a property owner “expect” to replace a BMP?
• When are maintenance agreements appropriate?
• What set of written recommendations can the subgroup provide that can be used by a homeowners association or other entity that may be responsible for O&M?
• What key documents should a HOA or other entity have on their files at all times in the event of an issue with O&M?

Monitoring:

• What situations can the subgroup envision that may require monitoring?  (i.e. quality of effluent or physical conditions of banks of receiving stream)

admin BMP Manual Revision BMPs, construction oversight, monitoring, O & M, operation nad maintenance, stream, vegetated

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:

Roads/Highways:  PennDOT has developed their own PCSM and Antidegradation Policy for highway projects.  The group can start by analyzing this document.

Does the group agree with this policy and/or does it recommend any changes.

What additional measures/BMPs, if any, does the group recommend for highway/roadway projects for:

• Volume Control
• Rate Control
• Water Quality
• Thermal Impacts & Antidegradation

Are there any existing BMPs that could be modified for a roadway or other linear project?

Other linear projects include trail systems & pipelines.

Trail systems are usually incorporated into a natural or park-like setting.  These projects are often low impact and involve minimal grading.   Some trails traverse or abut critical areas such as wetlands and stream watercourses.   What BMP approach would be recommended?

Some trail projects are more intrusive which is often dependent on their companion projects (i.e. they are sometimes related to a bigger plan of development).  These are normally treated differently since they are part of a bigger project.  The focus of this discussion should be on trail projects not related to a bigger project, however many of the ideas and BMPs could apply.

Pipeline projects usually do not propose any increases to impervious cover.  However, in many cases, pipelines change the land cover.  CN approach provides a relatively low CN for “brush” which is utilized by pipelines as the proposed condition.  This CN is lower than meadow and comparable with woods.  Does the group agree with this methodology?   Does the group believe that watershed protection is being addressed?   Is there another approach that can be taken for pipeline projects to achieve watershed protection?

Are there other linear type projects or issues related to linear projects that this subgroup can help address?

admin BMP Manual Revision BMPs, rate control, thermal impacts, trails, volume control, water quality, watershed protection

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/

admin BMP Manual Revision contaminated, LID, PA BMP Manual, redevelopment, special protection waters, special protection watershed, stormwater, watershed protection

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:

Much attention has been given to the “loading ratios” approach for sizing infiltration BMPs.  It has been found that this approach is better suited as a planning tool and default for practitioners who do not want to do a more thorough site assessment.  Therefore, this subgroup is tasked with developing clearer and more thorough criteria for sizing infiltration BMPs.  Questions:

Should hydraulic depth be utilized more as limiting factor (to avoid compaction at the air-soil interface)?

Should a risk-based approach to infiltration BMP design be incorporated into the manual?  For instance, should there be a maximum drainage area?  Should underground systems be designed more conservatively than above-ground systems?  What other factors should be considered in the design of infiltration BMPs.  See white paper for discussion on this matter.

Should mandatory pretreatment be incorporated into all infiltration systems (to what level  or particle size - 100 micron?)

Site evaluation and soil infiltration testing:

• Subgroup should reviewt and “beef up” the Soil Testing Protocol for infiltration BMPs
• Entire Appendix C, Protocols 1 and 2 should be evaluated for update.
• Infiltration Range from 0.1 to 10 in/hr;
• infiltration in fill (how long of a consolidation time before an area is no longer considered fill - 5 years?)
• Subgroup should review setbacks from dwellings, septic systems, drinking wells, property lines?  Should topography play a role - hillside hydrology.

Geological Issues (karst, other geologic formation, etc.)

• Should depth to limiting zones be kept at 2 feet.  Should it vary depending on soil permeability?
• When, if at all, should a mounding analysis be required?  Should PA follow NJ’s lead?

Water quality issues (nitrates)  (see Subgroup Topic E)

Infiltration on contaminated sites.  (See Subgroup Topic G)

Should infiltration of storms greater than the 2-year 24-hour event be “specifically” discouraged?   There are some municipalities who require infiltration of the 100-year storm.  Depending on the extent of the project, this can lead to issues in the future.  Many municipalities defer to the PA BMP Manual for technical guidance (MS4 etc.).   Discussion of this topic is important since infiltrating too much water has been identified as a concern.

admin BMP Manual Revision BMPs, infiltration, PA BMP Manual, planning, water quality

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:

Pennsylvania’s PCSM program has been set up in a way that focuses on volume control first.  Water quality has been determined to be inherent in volume control (with some consideration given to impacts from solute/nitrates)  There are many projects that, for one reason or another, are unable to achieve the Department’s volume control guidelines.  In those instances, more focus is given to water quality compliance.

1. Does the group believe that the 85, 85, 50 approach for surrogate parameters (TSS, P & N) is still the right way to go?  If not, then what other approaches are recommended?
2. Does the group believe that worksheets 10 through 13 are adequate for water quality compliance?  Are there recommendations for improvements or changes?
3. Do we want to continue with % pollutant removal for BMP performance?  What feasible alternatives are there for BMP Performance? (i.e. Volume, Concentration and Total Load)
4. Are there alternatives to using EMC?  If not, what new numbers do we have for the EMC and pollutant reductions that are listed on DEP Worksheets 12 and 13?
5. PA needs a WQ BMP sizing criteria.  Designers can not take the same % pollutant removal for a BMP receiving 1 acre of drainage compared to another receiving 5 acres.  There is currently no set criteria for this.  Perhaps a “loading ratio” approach would be appropriate here.  (perhaps even more so than for infiltration BMPs)
6. What new guidelines should we have, if any, for nitrates? (i.e. source control, fertilizer reduction, etc.)  Is there a minimum buffer width (or filter strip width) that we can say that nitrates (as well as TSS and P) are addressed?
7. Do we need to define a water quality storm in PA, as has been done in other states?  If so, what should it be and why?
8. Like it or not, manufactured products play a significant role in SWM. What are the gaps and how can they be addressed?  Should PA fully adopt the verification process (NJCATs) that has been developed for manufactured WQ BMPs?    If not, how can PA beef up its verification process for water quality BMPs?  How can PA establish a level playing field for manufactured products?  (In many cases, these products are swapped after permit issuance due to value engineering and regulatory agencies are put on the spot to grant approvals)
9. Should we be putting land based water quality BMPs (such as rain gardens) through a similar process as manufactured products to verify BMP performance?  If so, why and how?

admin BMP Manual Revision BMP performance, BMPs, buffers, PA BMP Manual, rain garden, volume control, water quality