A GOOD GRAVEL PATH

Landscape contractor Marilee Kuhlmann and landscape architect Tom Rao, of Urban Water Group, designed and built the gravel paths for water-wise drainage. Here is their procedure.

When we walk, drive, or move equipment over soil—or even just roll a trash can over the ground—we compact the soil. Compaction limits the infiltration of rainwater into the soil. A gravel path can be permeable if the soil under the path is minimally compacted. Eco-Rain cells or another recycled paver product is used to disperse weight over a larger area, which lessens soil compaction. A two-inch Eco-Rain device, made of recycled plastic, creates a more stable walking surface than would loosely laid gravel on soil. It can be installed for ADA compliance. Water is held in the gravel-filled chamber and slowly infiltrates the soil. The cost is approximately $8 to $15 a square foot depending on the materials used. Gravel needs edging to hold it in place; recycled material is more economical than steel or stone edging.

We excavate for a path a depth of 2 ¾ to 3 inches, then level the area, install the edging, and place an Eco-Rain drainage cell system on the soil. No weed barrier is used. The cell device is approximately 9 square feet and is cut to fit; the cost is about $30. We backfill the cell device with cheap, crushed stone to a ¾" inch depth. Crushed stone with sharp edges has more water-holding void space compared to rounded stone. We top with a

¾" layer of decorative gravel, which covers the last ¼" inch within the cells, then more gravel to cover the top of the device. The ¼" to ½" remaining in the excavated space limits stone from traveling or popping out of the path. urbanwatergroup.com

RIGHT (from top) The plastic drainage device and edging have been installed over the excavated pathways. • The finished gravel paths drain well without soil compaction and are very stable for walking compared to loose gravel without the open-cell plastic layer.