Abstract
In order to stabilize the construct effects of a pipe drain, it is necessary to use the filter material of a pipe drain. In this paper, we confirmed that the wood chip is suitable as filter material for a pipe drain.
The wood chip showed excellent permeability with a saturated hydraulic conductivity in the order of 10-3m s-1. It had also a wide C/N ratio and showed high resistance to rotting. The draining efficiency of the pipe drain using the wood chip was the same as that using a rice husk. The pipe drain using the wood chip had the sufficient draining efficiency 4 years later. The wood chip is easy to maintain the section of a drainage filter. And, the aging decrease rate of section area on the wood chip filter is smaller than its a rice husk, and the durable period of the wood chip as filter material is long. This reasons is that the rotting of the wood chip belonged to soft-rotting type, in which rotting is slow. But, the drain water of the pipe drain using wood chip was low pH condition. We expected that a pipe of underdrain using the wood chip was clogged by a iron deposit in a peat soil and a strong aside soil. Therefor, we concluded that the wood chip refrained from using as a filter material of a pipe drain in these soils.
