Massive Excavation Project Required No Vibrations From Construction

By Jeff Griffin, Senior Editor | January 2013, Vol. 68, No. 1

For most residents of Denver, CO, and surrounding areas, the Denver Union Station has been a city landmark for as long as they can remember.

The name Denver Union Station brings to mind the impressive stone structure dating from 1914. However, the first train steamed into Denver in 1870 and for the next few years, railroads built individual depots. In 1881, the first Union Station consolidated rail traffic under one roof.

In 1894, the original structure burned and was quickly rebuilt. Improvements made over the next several years changed the station’s look until the stone landmark of the last nine decades was completed in 1914 (see sidebar).

Today, Denver Union Station is undergoing the largest, most significant changes in its history. When complete in 2014, the new Denver Union Station complex will serve as a multimodal transportation hub, integrating light rail, commuter and intercity rail, as well as regional, express and local bus service, the 16th Street Mall shuttle, Downtown Circulator and intercity buses, taxis, other shuttles, vans, limousines and bicycles.

Project owner is the Denver Union Station Project Authority (DUSPA) which is responsible for the financing, acquiring, owning, equipping, designing, constructing, renovating, operating and maintaining the Denver Union Station redevelopment project.

Subcontractor Iron Woman Construction and Environmental Services, Denver, completed a large excavation in front of the main terminal building and formed and poured a concrete pad 83-feet long, 26-feet wide and two-feet thick, on which to position a precast, sectional, 8-foot-deep vault/tank with an 11,000 gallon capacity to capture rainwater and melting snow from the roof and parking lot of Union Station. Stored water will be released into the storm system in a controlled manner.

United Rentals Trench Safety (URTS) provided shielding and shoring for the excavation, which was installed by Iron Woman crews.

Evaluation

Shielding and shoring options were evaluated carefully during planning and design.

“Because one side of the excavation was only 26 feet from the front of Union Station, a primary requirement of the shoring system was to prevent any soil movement. No vibration was allowed,” said Kris Graham of United Rentals Trench Safety’s (URTS) Denver office.