The "Silver Bullet": Proprietary BMPs and Metropolitan St. Louis Sewer District's Stormwater Program

In February 2006, as part of its Phase II Stormwater Quality Management Program, the Metropolitan St. Louis Sewer District (MSD) implemented rules that require post-construction stormwater best management practices (BMPs) at development and redevelopment sites. MSD references the Maryland Department of the Environment's Stormwater Design Manual as a BMP design guide. However, this document does not specifically address proprietary BMP devices and currently there is not a national or Missouri state standard by which to evaluate them. For a proprietary BMP to be approved for use within MSD boundaries, the device's manufacturer must present it to MSD and request approval for one or more use levels. Possible use levels include General Use Level, Redevelopment Use Level, Highway Use Level, and/or Provisional Use Level. Submittal requirements and use level descriptions are provided in Proprietary Water Quality Products and the MSD's Stormwater Management Program (rev. Jan 2009), which can be downloaded from the MSD web site (www.stlmsd.com). Devices are approved for a particular use level based on (1) the treatment performance requirement for that use level and (2) the certified performance of the device. Performance certification testing must comply with the Technology Acceptance and Reciprocity Protocol (TARP) or the Technology Assessment Protocol-Ecology (TAPE). When approved for use by MSD, each device is issued an approval letter that is posted on the MSD web site. Advantages of the process include (1) MSD recognition that the device is effective for its use, (2) manufacturers quickly ascertain whether their product can be approved, and (3) BMPs that meet requirements are approved in a reasonable time period.