Please send feedback to:
Angela Gallardo – Kitsap County [email protected]
2018 Permit Discussion-LID
Subgroup Issue #1: Flexibility re: BMP Selection
The Appendix 1 list approach/hierarchy is too rigid. There are many nuances that can make one BMP work great at one
site and fail at another.
Ecology Response:
The LID performance standard does provide flexibility that the list approach may not. Infeasibility criteria are broad
categories, but are evaluated on a site specific basis.
Current subgroup thinking:
The group has discussed revising Appendix 1 language to allow greater functional equivalency, particularly for pervious
pavements. To inform that discussion, we are asking for insight into two questions.
• What is Ecology’s general logic for adopting the Minimum Requirement #5 LID Lists?
• What was Ecology’s the rationale/basis for placing one BMP as preferable to another on these lists?
Subgroup Issue #2: Adaptive Management
Emerging technologies/BMPs/knowledge can only be made available through manual and permit modification. This is
slow and burdensome and affects our ability to take advantage of the latest thinking. Is there a more efficient way to
utilize emerging technologies? A parallel process to TAPE was discussed.
Ecology Response:
Ecology must cite a specific version of the SWMMWW in the permit, this provides certainty to local governments and
developers. The Pollution Control Hearings Board ruled on this issue (re: referencing specific versions of guidance
documented in the permits).
Emerging treatment BMPs (including non-proprietary BMPs) can be evaluated through Ecology’s Technology Assessment
Program (TAPE), referenced in the manual. WSDOT was successful at creating new BMPs through this program.
Current subgroup thinking:
When Ecology approves a stormwater BMP for use based on successful demonstration of the technology through the
TAPE program, they write up a General Use Level Designation (GULD) document. The GULD specifies what level of
treatment the BMP is approved for and under what conditions of use. For example, the Modular Wetland System’s
Linear Modular Wetland BMP has a GULD for Basic, Phosphorus, and Enhanced treatment. Could the GULD document
include a statement from Ecology that would approve BMPs to meet the LID BMP listing along with conditions of use?
Their use would not be required (until the permit is modified) but could be allowed at this earlier date. The Permit along
with Ecology’s SWMMWW would need to be revised to allow the list of LID BMPs to be supplemented with stormwater
BMPs approved through TAPE per the specific BMP’s GULD and conditions of use.
**This would only address water quality BMPs, so another mechanism would have to be used to address flow control
adaptive management.
Subgroup Issue #3: Bioretention Media
The group is concerned about exporting pollutants using the current soil mix. Jurisdictions could trigger S4.f
notification/planning and be required to implement costly retrofits or replacement of soil in future.
Ecology Statement:
Leaching is only a problem in systems with underdrains. Limits are in place when discharging to a phosphorus impaired
waterway. The benefits of bioretention outweigh the negatives. (This is a generalization of Ecology’s comments.)
Current subgroup thinking: We are still concerned by this situation. Our comments regarding adaptive management
also apply here; our hope that current research will lead to an improved soil standard. Further, there is concern that the
current criteria for alternative bioretention soil mixes with the SWMMWW, also does not appear to align with the
preliminary scientific results.
Subgroup Issue #4: Coordination With Other Areas Of The Permit
Subgroup feels that more clarity is needed re: expectations relating to GIS, O&M/Inspection, and Source Control for LID
BMPs/facilities. Full onsite infiltration removes site from MS4. How will this affect other parts of the permit?
Subgroup issue #5: Maintenance/Life Cycle Cost
When developing the current permit, there wasn’t a way to maintain permeable pavement. The market still hasn’t
found a solution to this problem. If jurisdictions are going to allow ROW improvements to include BMPs like permeable
pavements, we need to know how to plan for long term maintenance.
How can we assess cost if we don’t have a way to maintain?
Ecology Statement:
Maintenance costs was considered in developing the LID list approach and was considered reasonable in order to meet
AKART.
Maintenance costs can be considered when following the LID performance standard.
When following this approach, one can use the range of BMPs in the manual to meet this standard, and choose not to
use a particular BMP because of the maintenance.