Greetings First Street Tunnel Stakeholders,
Update on Abigail, micro-tunnel boring machine (MTBM) that is currently mining the Adams Street adit tunnel
Abigail, the MTBM, has encountered challenging ground conditions under Adams Street, causing SKJD to work in an emergency mode-around the clock (24/7) since Monday night, April 11th. The underground soil conditions have proven to be more difficult than expected. Changing soil conditions, including moving through sections of clay, require that ground surrounding the machine be stabilized as the soil conditions are encountered. In addition, crews have encountered high groundwater pressure so the pace of mining is slow.
At this time, SKJD is installing only one pipe segment per day. There are eleven more pipe segments to go. Therefore, the operation needs to continue in an emergency mode 24/7 uninterrupted until all 11 pipe segments, each 10 feet long are safely installed underground.
At this rate of production, we expect to be in emergency mode for the next 11-12 days.
SKJD has notified the permitting authorities as required, and has received permission to proceed with the 24/7 hours to complete the critical tasks for safety reasons. Please be assured that the public and adjacent buildings are not at risk. We need to complete the underground work as described above since should the MTBM machine become immobile, it would require the contractor to be retrieve the MTBM through an open cut from the street. Open cut construction would produce more adverse construction impacts to the abutting community than the current plan.