64 Photos - Aug 29, 2013
Photo: Are you ready for a tour of how to assemble a Parking Forest? Photo credit: Brian WegenerPhoto: First we sawcut the pavement. There's Brian Wegener of the Tualatin Riverkeepers, the mastermind behind the Parking Forest.Photo: "Depave" volunteers removed and haul away the asphalt. We did some outreach on this day, too.Photo: Depaving is hard work, no doubt about it!Photo: Here's the site at the end of our depaving event.Photo: On construction day, materials were delivered and stockpiled. Here's the structural soil.Photo: The contractor is removing the base rock below the asphalt. This material was stockpiled on site for reuse.Photo: Another photo of rock removal. The structural soil is on the right-hand bottom of this photo.Photo: Lee is digging out the native soil (a pretty clayey material). Most of this, but not all, was hauled off site as clean fill for another project.Photo: Another photo of the soil being removed. Always work outside of the infiltration area with your equipment, even if it has a track or flotation tires, which are less compacting.Photo: Video: Look how hard this soil is in the middle of summer. Watch the track on the left as it's lifted up.Photo: Excavation was down to about 27 inches below existing grade throughout the trench.Photo: Finally wrapping up soil removal. The catch basin in the foreground wouldn't be needed for overflow in future projects, but our demonstration required a way to sample water quality, so we included this.Photo: As mentioned, some of the native soil was stockpiled to be reinstalled down the middle planting strip. Here, Lee is mixing 2 parts soil and 1 part compost.Photo: Here's a great photo of the native soil stockpile and the beautiful, fully composted, black US Composting Council STA compost we used.Photo: An impermeable liner along the sides that abut the asphalt will protect the existing impervious asphalt from being undercut by any water that might be stored in the voids of the structural soil until it can infiltrate. This was nailed in and cut.

Also, notice that the bottom isn't smooth anymore. Here you can see that we ripped the bottom with a bucket with forks/teeth in what my geotechnical engineer thinks might be a vain attempt to help out infiltration.

You can also see the first lift of structural soil on the bottom left starting to be placed.Photo: Another, better photo of the structural soil and the truck that delivered it.Photo: Our contractor, Jack Castillo of Confluence Construction and Restoration NW sizes up the pile.Photo: Well, some pictures are missing because I had to take care of some things, but you can see the sequence of lifts very well on the THPRD Sunset Swim Center site.

Essentially, the contractor placed an 8" lift of structural soil on the left and right outsides, and lightly compacted it. Each lift was tested twice on each side to ensure proper compaction. A few times, it was under, so they ran their one-person vibratory compactor over the area again.

After that, they placed a lift of compost amended soil in the middle. They worked their way up until they finally placed the finish rock (1/4"x10) in the planting strip.Photo: The catch basin was placed at the low point so that it could be connected to the pipe assembly and overflow out that before it overflowed out the lowest corner of the pavement cut. Here we are digging out the level spreader, which was used to spread overflows out and reduce erosion.

Remember, if you don't have to monitor for water quality, you don't the catch basin, the overflow assembly or the level spreader. Overflow can bubble out the lowest pavement edge and continue on the way it would have before you retrofitted the site with a Parking Forest.Photo: To compare the trees in the trench with an ideally planted tree, we compost amended a part of the landscape area. Our control tree will go there.Photo: Another overall of the site.Photo: Parking forest at pcc sylvania... end of day 2. Now we wait for asphalt on either side of our planting trench. Trees to be planted in Oct when the rains come.Photo: The contractor installed the boards so that the asphalt contractor would know where to stop paving, then spread out the rock.Photo: To clean the pavement, the contractor washed everything from the asphalt above where materials were stockpiled into the trench. I might worry about the permeability of this material (because water transported clay can clog surface soils) but it's going to be paved over with asphalt anyway.Photo: Photo: After the asphalt contractor was here. They left a bunch of sand at the edges, which was swept up on the lower end by others to control erosion and protect water quality. The upper side was left as is and the sand ended up in the planting strip after the first rain event.Photo: The crushed angular 1/4"x10 was brought up to grade with an ever so small dip in the middle.Photo: The level spreader was lined with salvaged river rock.Photo: The level spreader and overflow outlet from the other side with the wheel stops in place, too. When runoff from uphill fills the trench, it flows out of the green grate and into the level spreader.Photo: Here you can really see the gaps in the wheel stops. These are old-school wheel stops that were donated. It would definitely be better to have the newer style, which have feet, so that water didn't concentrate so much at the gaps.

This has caused the rocks to move around. In the future, I think I would suggest finishing this area with Xeriscape pavers, but we just didn't have the budget in our grant.Photo: Photo: Brian Wegener comes to to kick the tire, so to speak. You can see how tree needles washed into the planting strip in between the wheel stops.Photo: A close up of the sand and tree needles. This was from a small storm, and I can tell it didn't overflow because there's no material on the low side (right) of the planting strip.Photo: Photo: Here's the Parking Forest working away in a larger storm after two days of larger storms.Photo: We have to wait to plant the trees until the rains come because we have no irrigation out here. Can you see in the foreground in the rock how someone drove through this already?

We hope this won't happen as often once the trees are installed, which will draw more attention to how these 8 parking stalls differ from the rest of the campus standard.Photo: The parking spaces are still plenty big to accommodate my Subaru wagon.Photo: Photo: Even though people don't park this far forward in the spaces that don't have wheel stops, people are driving over the wheel stops and into the softer amended soil.Photo: Photo: Photo: Here's some erosion for you. This is why I wanted wheel stops with feet, which wouldn't concentrate the runoff as much.Photo: Photo: Photo: Photo: The HOBO will tell us what the water levels are through all the storms it experiences, so we know when there are overflows. This will help the Portland Bureau of Environmental Services figure out what size storm they should run out to sample this spring.Photo: Maintenance by students fulfilling their service requirements. I've got them scooping out some of the worst dirt that was scoured during our earlier storms. This is probably a once a year maintenance practice that should be done after the end of our long summer, just to protect the infiltration capacity of the surface trench.Photo: Photo: Here's what they pulled out of the planting strip. I'm not worried about the organics, just the fine clays. We'll wash this with a hose off-site and place it back on the surface.Photo: More maintenance... cleaning up behind the wheel stops on the upside to help ensure that water doesn't block the inlets between the wheel stops.Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: Photo: