As you may have seen in Jeffery Leib’s article in Monday’s Denver Post, work on the bus box has been suspended while a beefier dewatering filtration system is installed and approved by the state. The green tanks in the photo below contain the original charcoal filters that have been prone to clogging due to high levels of iron. The new blue and yellow filtration units are intended to remedy the situation.
In the meantime, ground water is seeping into the bus box hole such that nearly the entire floor is now under water, as you can see in the photo below.
Once the ground water situation is resolved, work can begin on the concrete floor called a mud slab, and digging inside the three sheet pile holes will begin. Those holes are for plumbing vaults which will be ten feet deeper than the current floor of the bus box hole. A pit for the bus terminal elevator will be dug in the same vicinity but will be only four feet deep and will not require sheet pile.
The stone roadway seen on the right in the photo above is the pathway for the crane that is pictured in Update #17. The crane will move along the road as it sets in place the structural parts of the bus box. The structural material staging area is up and to the right of the stone roadway.
There is also progress on the light rail system. Work has begun on foundations for the overhead catenary system (the power delivery system for the light rail) along the future light rail tracks beside the consolidated main line tracks. Also, workers have started backfilling between the two new light rail retaining walls. Eventually, the surface will be raised to the top of the retaining walls before the new tracks can be installed. The relocated light rail station is expected to be completed and in service by the spring or summer of 2011.
There is also progress to report at the temporary Amtrak terminal at Wewatta and 21st streets. Interior walls are being framed and electrical work is underway. Part of the interior concrete floor had to be removed for placement of new utilities. That work has been completed. An insulated water line will be built over 20th Street to supply water to the area near the temporary Amtrak platform. The water is needed to clean the trains and replenish potable water in passenger cars. The need for water at the platform is yet another item that falls into the category of, “I never would have thought of that.”
In Update #18, I mentioned the application of a coating on the two mountains of dirt. It has proved to be very effective. There is no evidence of erosion after last weekend’s rain.
I uploaded 12 new photos to our Denver Union Station page at JobSiteVistor.com including the the two photos in this post.
Thank you to Hunter Syndor of Kiewit for providing the information in today’s blog.
Remember the first walking tour is this Thursday.
How do we know that’s groundwater seeping in and not just rain that has accumulated?
I don’t know exactly how deep the water table is here, but are we building something that is going to have to be permanently pumped like the NYC subway system is, and it will consume huge amounts of electricity just to stay dry?
Matt, good questions. Hunter Sydnor of Kiewit told me that it is ground water. I was not in town last week, but I believe that water started accumulating prior to the weekend rains. The rain probably aggravated the situation. Several weeks ago, I also learned from Hunter that the bus box will be water-tight and will not require constant pumping. In fact, the plan is to dismantle the dewatering system once the project is complete.