16 Photos - Aug 29, 2013
Photo: Courtesy of Brian Wegener of the Tualatin RiverkeepersPhoto: Courtesy of BrPhoto: Courtesy of Brian Wegener of the Tualatin RiverkeepersPhoto: Courtesy of Brian Wegener of the Tualatin RiverkeepersPhoto: Courtesy of Brian Wegener of the Tualatin RiverkeepersPhoto: Courtesy of Brian Wegener of the Tualatin RiverkeepersPhoto: The rock for the porous pavement was already placed when we started the trench.Photo: First, the contractor marked down the center line and measured 2 feet on either side so they'd know where the structural soil should end.Photo: The native clay was amended with compost and Permamatrix (a soil amendment with mycorryhzae, biota, biochar, and other goodies) and then placed down the middle. Both materials were watered down. The structural soil is being compacted with a small vibratory compactor.Photo: We tested each lift of structural soil (woman in yellow jacket on right) in a few places to ensure that the compaction levels were between 85 - 90%. Due to a dry-ish mix and the variability of this material, a few of the spots we tested were undercompacted after two passes. In these areas, the contractor wet the mix and ran one more pass with the compactor, then we tested it again.

A note: Wetting the soil after it's in place isn't ideal for achieving compaction, but it's what most contractors do. We tested compaction at different depths to ensure this method would be sufficient.Photo: Water compacting the native soil portion...Photo: The contractor continued the previous process until...Photo: ...all the layers were in place.Photo: Pervious concrete was poured directly onto the structural soil.Photo: Courtesy of Brian Wegener of the Tualatin Riverkeepers. Pictures of the two aggregate sizes of pervious concrete (small and really small).Photo: The landscaping crew came in later and placed the rock and planted the trees.