When you construct your street-side stormwater-harvesting basins, described in my last post, Harvesting Stormwater with Backwater or Eddy Basins, you’ll of course want them to be as successful as possible; to that end, understand and equip yourself with these important engineering tips:
Important Elevation Relationships of Backwater Basins
The following is based on tip 9 (Three Key Elevation Relationships of Water-Harvesting Earthworks) from chapter one of Rainwater Harvesting for Drylands and Beyond, Volume 2, by Brad Lancaster.
Elevation 1: Bottom of basin, and the top of the mulch within it, is lower than the elevation of the curb-cut inlet so the structure accepts and holds street runoff. The deeper the basin in relation to its overflow, the greater its water-holding capacity.
Elevation 2: Curb-cut inlet is the low point of the basin’s perimeter, so water will overflow at (or back up to) the inlet and the pavement-stabilized street-curb gutter.
Planting terraces are typically the same elevation as the curb-cut inlet (and higher than the bottom of basin), so plants less water-tolerant than those in bottom of basins will thrive—allowing for a greater diversity of plantings. Terraces also reduce the otherwise-sudden drop a basin would represent along adjoining paths and pedestrian platforms.[. . .]
For the Elevation 2 illustration, Elevation 3 text, a learn-from-my-mistake opportunity, and a few guidelines for inlets of curb cores or curb cuts, read the rest of this post on my Drops In a Bucket blog.
For more information and examples, including how to increase the capacity of these basins, buy, read, and share these award-winning books (most of the info on this page came from Volume 2):