2018 Update #49

Gumbo Clay

October arrived and with it some unsettled weather. Our construction crew weathered the week’s occasionally heavy rain and notched up another productive week.

Let’s look at the details.

Your Weekly Construction Update

As planned, the Tunnel Boring Machine continued its 152-foot journey under Main Street to Receiving Pit 2, the southern arm of the drainage system located trackside behind Triangle Park.

ECI and Robbins have adjusted their process, increasing pressure and the speed of the drilling head so that they are now averaging about 20 feet a day. As of end of day Thursday the TBM sits 100’ deep into this second tunnel and should break through into Receiving Pit 2 mid-week next week.

This week Kubricky turned its attention to excavating Receiving Pit 3, the northern arm of the new drainage system, located alongside the rail line in the Marble Works.

Five feet into the excavation, Kubricky hit clay (“gumbo clay” in the words of one Kubricky manager; see photo) and that will be the case for the remainder of the excavation. That means a) no blasting, b) no line drilling, and c) no hammering.

Kubricky will continue excavating Receiving Pit 3 during the next two weeks, preparing for the TBM’s final run of 130 feet from the Launch Pit. That should get underway the week of October 15.

ECI also began grouting the space between the steel casing and the bedrock (you may remember that this is referred to as the annular space) in the first tunnel. The photo below is looking from Riverfront Park 140 feet to the Launch Pit.

Tunnel boring is running ahead of schedule and at this point Kubricky hopes to complete this part of the project before Thanksgiving. Finish work on the drainage system and utility work lie ahead as we close out the year, and I’ll cover those efforts in the weeks ahead.

In the meantime, hope you enjoy the Columbus Day weekend and the arrival of Fall foliage.

That’s all for today. See you downtown.

Please keep your comments and questions coming. Send me an email at jgish@townofmiddlebury.org and I’ll try to cover it in my next update.