There is art as well as science to creating a good drainage ditch.
Along with the retaining wall, we are having the site drainage reworked. Old ujiko (U-shaped concrete forms) have been removed and will be reused behind the barn and new ones arrived for the house surround. At 30kg, they are too heavy for me to lift and most of this work required expertise, so I have stuck to mostly observing for the last couple of days.
On Tuesday, Sakaguchi-san pulled out his surveying equipment and spent half a day to get the line of the ditch just right. He took many measurements, pounded in stakes, then moved them, pulled strings and checked their heights. Sakaguchi-san is the team member who values precision and and is patient with details – I have huge respect for him and a lot to learn.
When he was satisfied, then the digging started. Mostly it was done by Shimizu-san and the backhoe, but some of the tricky spots, like the deeper corners where the masu (junction boxes) sit needed to be dug by hand. It was very hard work in the grey clay soil. The raw ditch was filled with large rocks and tamped down to finish up the work for day 2.
Yesterday, each ujiko section was laid on a bed of sand and carefully leveled. Spacers ensured consistent gaps which were mortared by Abe-san. It is precise and I hope it is accurate because there is a lot of water coming off the mountain. Even as the ditch was dug, parts of it got damp. I am sure it’s always been this way, though perhaps even more since 2019’s typhoon.
As the yumbo dug along the north wall on Wednesday, we discovered a series of heavy wooden posts evenly spaced and sunk into the clay soil holding back a long horizontal log buried (now) a bit lower than the base of the north slope. Shimizu-san reckons they may be as old as the original house – 120 years. Kawasaki-san didn’t know about them at all, so definitely before his time.
The north side of the drainage is done. Next the west side and the complicated parts around the barn. If the weather holds, it might be done next week.
