Looks to me like the stomwater 6.2 quality control is only achievable with engineered BMPs to treat runoff.
Has anyone successfully used lower-tech treatment and actually gotten the points?
80% of TSS must be removed….from my research looks likea spare few BMPs have performance data to meet this requirement and they are essentially engineered stormwater structures. Over the weekend I talked to an LA from across the state and she said they had done the fairly exhaustive calculations and design several times, but have never been awarded the credits.
Bio-swales, rain gardens and water spreading are very low tech and very effective BMPs that can provide all of the required treatment and infiltration if space, slope and soils provide the opportunity. Permeable paving is also a big help to reduce the peak and annual volumes. If you are able to convey to vegetated basins and infiltrate design volume there is no need for stormwater treatment structures. This is a preferred method. We are in review for 6.1 and 6.2 on a current project and don’t anticipate any problems as our local stormwater requirements exceed the LEED peak storm events. I realize many projects have don’t have the needed space for storage of the planned impervious surfaces, and the 6.2 credit may be very difficult to achieve otherwise. I don’t know of any projects that have achieved them without some sort of integrated approach. Engineered structures typically won’t cut it on their own. Utilizing an integrated approach that minimizes the impact on the natural hydrology is the aim of the credit.