Urban Stormwater Workgroup Conference Call Minutes September 23, 2008 Highlights and Action Items • DECISION: The Urban Stormwater Workgroup approved the infiltration and filtration practice recommendations as proposed by UMD/MAWP. Members agreed that we should move forward with using the mass-based total removal values (TR values) for these practices. • ACTION: The Urban Stormwater Workgroup's recommendation will be submitted to the Watershed Technical Workgroup for review in advance of their October 6th meeting. Handouts Meeting Website: http://archive.chesapeakebav.net/calendar.cfm?eventdetails=9797 • UMD/MAWP Recommendations for Infiltration and Filtration Practices • Infiltration and Filtration Practices Panel Response. 9-4-08 • Center for Watershed Protection Technical Memorandum: The Runoff Reduction Method • Center for Watershed Protection Technical Memorandum: Appendix F Minutes • Reggie Parrish, USWG Coordinator, began the conference call at 1:00 pm. Introductions were made and the conference call's agenda was reviewed. • The purpose of this conference call was to finalize the workgroup's recommendation for effectiveness estimates for infiltration and filtration practices. This recommendation will be based on the infiltration and filtration report developed by UMD/MAWP as part of year two of their BMP project. • At the August 26th USWG conference call, workgroup members expressed concern that UMD/MAWP used the runoff reduction method to determine effectiveness numbers, when not all of the watershed states use this method. The runoff reduction method was developed by the Center for Watershed Protection for use in VA. • Since the August 26th call, Sarah Weammert, UMD/MAWP, brought this issue up with the expert panel that had assisted in developing UMD/MAWP's original recommendation. UMD/MAWP and the panel decided that they still recommend the use of the total removal (TR) values that were already presented, which were calculated using the runoff reduction method. • If the USWG decides not to use the TR values, then pollutant removal (PR) values could be used. The PR values that are proposed by UMD/MAWP are found on page 2 of the panel response document. • Today, one of the decisions that the workgroup had to make was whether to use the TR values or the PR values. Discussion • Kate Bennett was concerned that the jurisdictions were being asked to try to account for the maintenance of individual facilities, when in some cases they don't even have 1 ------- a good idea of where all of the facilities are located. Trying to track whether these facilities are properly maintained would be difficult. o Jeff Sweeney explained that for all of the BMPs evaluated in this project, including those in other sectors, UMD/MAWP chose values lower than the average literature values to account for factors such as improper maintenance. • UMD/MAWP and the panel still recommend using the TR values, which were calculated using the runoff reduction method. Workgroup members were asked whether they had any objections to using these numbers. o Ken Pensyl: If we decide to use the TR numbers, how will we determine whether the practices were installed on either a/b soil or c/d soil? Jeff Sweeney said that CBP will use the predominant soil type in that land segment. o How will Jeff Sweeney know whether or not there is an underdrain? - For bioretention, the default will be that there is an underdrain. If there is no underdrain, it becomes an infiltration practice, o In addition to VA, DC is also planning to use CWP's runoff reduction method. This method is included in DC's updated stormwater regulations, which still need to be approved, o MD is not using the runoff reduction method. They are using a different approach in which they are moving away from individual BMP tracking, o Workgroup members decided to recommend the use of the TR values, and not the PR values. • Jeff Sweeney said that the jurisdictions are currently only reporting practices as either infiltration practices or filtration practices. They are not reporting what category their filtration practices fall into (the UMD/MAWP provides effectiveness estimates for several different categories of filtration practices). If a jurisdiction doesn't specify which filtration category a practice falls under when they report their information to CBP, how should this be handled? o It was suggested that there be a default value. o At the August 26th meeting, USWG members agreed that when jurisdictions do not specify which filtration category a practice falls into, then the filters category will be used. • Jeff McKay asked how UMD/MAWP came up with the effectiveness estimates for TSS in bioretention practices. o Jeff Sweeney said that UMD/MAWP used the same protocols for all of the BMPs in this project. Essentially, they took an average of all of the literature values that they could substantiate, and then they backed it off a little. They also rounded the number to the nearest zero or five. • In year 1 of this BMP project, an effectiveness estimate of 60% for TSS was approved for wet ponds. Does this make sense when compared to the effectiveness estimates that are being recommended for infiltration and filtration practices? • Reggie Parrish said that the guidance for tracking and reporting that is posted on the CBP website will need to be revised based on this document. DECISION: The Urban Stormwater Workgroup approved the infiltration and filtration practice recommendations as proposed by UMD/MAWP. Members agreed that we 2 ------- should move forward with using the mass-based total removal values (TR values) for these practices. ACTION: The Urban Stormwater Workgroup's recommendation will be submitted to the Watershed Technical Workgroup for review in advance of their October 6th meeting. • The conference call was adjourned at 1:35 pm. Participants Kate Bennett Mark Berkhead Sally Bradley Tim Karikari Jeff McKay Lisa Ochsenhirt Reggie Parrish Ken Pensyl Jeff Sweeney Fairfax Co., VA PA DOT CRC/CBPO DDOE PA DOT AquaLaw EPA/CBPO MDE UMD/CBPO kate.bennett@ fairfaxcountv.gov sbradlev@chesapeakebav.net timothy.karikari@dc.gov lisa@aqualaw.com parrish.reginald@epa.gov kpensvl@mde. state, md. us i sweenev@chesapeakebav.net 3 ------- |