In Spring 2015 final plans were developed to depave the area outside units 1 through 4, a total of three and a half additional parking spaces. This area had served as our container garden for several years as plans evolved to transform this space into a permanent garden.
In late Spring we cut the asphalt into 3’x3′ tiles to prepare for a weekend blitz to remove the asphalt.
Several days later the big day for our community asphalt removing work party arrived. It was very hot but we had a tent set up to shade participants and plenty of snacks. Asphalt removal was more difficult than anticipated when we discovered it was extra thick and the cuts did not go all the way through in some areas. Nevertheless, with a great community effort, all the asphalt was removed by the end of the day. We removed a total of 4 dumpsters of asphalt chunks!
Removing the Middle Asphalt
A second work party was organized in the Fall to remove the gravel and prepare a winter cover crop. Removing the asphalt, we discovered what appeared to be a gravel filled trench running along the sidewalk and a large amount of gravel in the center. That graveled center area seemed perfect for a patio. We did not think too much about the trench and just covered it with plenty of compost.
After the final perimeter gravel removal, we placed a large amount of compost on the area and then seeded it with daikon radish, chosen for its deep tap root’s ability to penetrate the heavy, very compacted, clay soil.
One final surprise awaited us a few days later on Halloween day as residents were preparing holiday decorations for an evening party in the basement community room, below the depave site. There was a sudden and sustained downpour and all of a sudden, water started pouring into the room from the adjacent basement crawl space. Apparently the heavy downpour saturated the depave site and overflowed into the gravel trench, making its way into the basement crawl space next to the community room. Fortunately the flooding was intercepted by residents before it did any damage. We installed a sump pump in the area as the water flow into the crawl space continued intermittently for the duration of the Winter and Spring rains.
By the next year, we were not sure if the basement leak had completely resolved since there was no problem with gentle rains and downpours are very infrequent. We had had no further flooding into the community room. We suspected the problem was due to a gravel filled trench in the depaved area that contained utility lines. The compacted soil on both sides was relatively impermeable compared to gravel, so rainwater would run into the trench and immediately proceed to the basement crawl space.
The final step in the depave process was planting perennial natives as well as annuals and some vegetables. One of the nicest features of this area is a large hollow stump out of which flows the entire rain water collected from the south half of the roof area. Even during a gentle rain this area now comes alive with a babbling brook and crosses under the bridges.
Eventually, we decided to cap the trench area with a heavy clay layer to minimize risk of any further water entering the trench and making its way into the basement. This appears to have solved the problem, as well as continued cultivation of the formally compacted area, which is now more absorbent of water.
We have had no further problems, even during the heaviest downpours.