Transportation agency to install two types of measuring instrumentsThis month, the Oregon Department of Transportation will be installing underground instruments within the West Commercial slide area to help the city make informed decisions about future management of the slide zone.
Two types of instruments will be installed: Inclinometers will help determine the depth of the slip plane, and piezometers will provide information about the depth of the groundwater table. The city's geotechnical consultants have identified six monitoring locations in the slide zone. An inclinometer and a piezometer will be installed at each location.
A seventh monitoring location will be established uphill from the known slide zone in Duane Street. This location will serve as a sentry point, to monitor whether the slide is likely to advance further up the hill.
City crews will be doing some brushing and preparatory work in the area over the next two weeks. ODOT will begin the actual drilling work Monday.
Once drilling starts, it is expected to take about three weeks. There will likely be impacts to parking on both Commercial and Duane streets while drilling is in progress. Also, it will be necessary to close Duane Street between First and Second streets while drilling is in progress. The alternate access from Third Street will be open during this time, and affected residents will be notified in advance with door hangers.
Concurrent with the drilling work, the city will re-establish a water main that was taken out of service by the recent earth movement.
The city urges drivers to avoid Duane and Commercial streets as much as possible while drilling and waterline construction are underway, as parking and access restrictions will make things inconvenient for many area residents.
It is requested that the barricades be respected, and the slide zone not be entered. The surface of the ground is very uneven, and new vegetative growth has hidden many deep crevices.