Roof runoff and seepage under the shuttered Blue Heron mill in Oregon City is getting a 6-foot wall of compost to filter the water before it returns to the Willamette River.
The compost Pettey uses looks like playground tanbark -- he found a chewed up Lego in one batch. But this bark has cooked in compost for six months, picking up microbes and fraying the wood to better catch larger waste particles. At the mill, the Gullywasher crew packs it into green mesh composting "socks" designed to absorb heavy metals. These are stacked, layer by layer, into metal cages so that the dirty water hits the compost first, then washes through a second layer of drainage rocks. Stripped of zinc, copper and any other contaminants, the water runs straight down the bank and into the Willamette.
Pettey said this system is a first for industrial wastewater cleanup. A main advantage is that it requires far less electricity and manpower than the current process, which pumps the affected water -- with some stops in between -- to a lagoon in West Linn. Darwish said the compost system will save money for the land's trustees and make the clean-up more environmentally friendly.
Read more at OregonLive.com.