This week we’re looking at one of our recently completed projects constructed in Hillsboro, Oregon through the developer, Trammell Crow Company, for tenant GXO, a global contract logistics company that manages outsourced supply chains and warehousing. A concrete tilt-up structure with steel decking and fully insulated, this 270,000 SF building is primarily filled with racking, offices, break rooms, restrooms and conference rooms, as well as both a walk-in cooler and freezer, and electric forklift chargers. In addition, the site includes 27 dock doors, vehicular parking, electric vehicle charging stations and a large bio-swale and landscaping.
A few challenges with construction as well as unique features, however, make this structure one to talk about!
The AutoStore System
Perlo prepared a portion of the warehouse space to receive a robotic package picking system by AutoStore, which the owner supplied to help automate warehouse operations. This custom fulfillment system was placed under a ceiling grid and on top of an extremely flat concrete floor. The area also included a beam detection fire alarm system.
The AutoStore system operates with small robots in an aluminum framework and can continue to work 24/7. Smaller in size than a forklift and needing no room for people to move between the racks, the storage space allowed inside this system for inventory is virtually unbeatable. The robots can move between racks and pick individual packages, and the structure can be made in any shape, form or height. According to the AutoStore website, ten of these robots use the same amount of energy as a vacuum cleaner.
Floor Flatness and Floor Levelness
To understand the unique nature of the concrete floor that Perlo installed under the AutoStore system, it’s important to discuss what Floor Flatness (FF) and Floor Levelness (FL) really mean.
Most would say that any concrete slab inside a warehouse is flat to the naked eye. However, this isn’t necessarily true. For instance, concrete has traditionally been considered ‘flat’ if it deviates less than 1/8 over 10-feet. In 1979, a system called the Face Floor Profile Numbering System was developed, which was later formalized and adopted by ASTM and ACI. Tools were created to better measure how flat a given concrete floor actually is. The following definitions describe Floor Flatness and Floor Levelness:
Floor Levelness (FL)
Applicable to slab on grade, floor levelness is based on how closely the finished floor matches the design document’s specifications for the intended slope. Higher FL numbers indicate a more level floor.
Floor Flatness (FF)
Floor flatness measures how wavy or bumpy a floor is. Floors with higher measurements are flatter than lower measurements.
For a better representation of what these measurements equate to, see the below chart from Archtoolbox:
The GXO floor was designed to have an FF/FL of 75/75, which, according to the above chart, means it’s even more flat and level than ‘Super Flat’.
For additional reference, the American Concrete Institute has provided guidance for typical FF/FL specifications depending on the use:
Huge congratulations to our teams for achieving such a flat and level floor for GXO on this project. It’s no easy feat to achieve!
“The ownership and development teams were very receptive to proactive coordination, and we had a lot of it. They even had people fly in from out of town to walk the site and make decisions. All around, the team was great to work with. GXO, Trammell, Mildren Design Group, AAI engineering, it was a really fantastic team.”
Construction Challenges and Schedule
In reality, most projects in today’s climate are running into material lead times. In addition, wet weather can cause less-than-ideal working conditions and potential setbacks. Here’s how we handled some construction challenges along the way:
The full construction of the core, shell and interior build-out was completed in less than 1 year, with much of the sitework underway during the wet-weather season. The team persisted in building despite having 99 days with 1/10th of an inch or greater rainfall between August and June. To combat these conditions, they employed a variety of techniques, including:
- Strategic planning for concrete pours to take advantage of short weather windows
- Use of concrete curing blankets to prevent defects in the concrete
- The use of a schedule acceleration allowance to pay for weekend work for concrete pours
- Installation of plywood at all window openings while waiting for the aluminum frames and glass.
Permitting challenges and solutions
Just before to the issuance of the building permit, the City of Hillsboro asked the design team to relocate the building approximately 10’ away from the property line to achieve more distance between this structure and any future structures on the neighboring property. With such late notice and preconstruction efforts well underway, the team investigated alternatives to relocating the building and landed on the installing a ‘Water Wall’ sprinkler system along the South side of the building.
What is a Water Wall? Essentially, it is fire sprinklers mounted on the exterior of the building that is triggered to engage in the event of a fire. The idea is to prevent fires from spreading between buildings. These systems are installed by the Fire Protection subcontractor and are tied into the fire alarm and electrical systems, requiring significant coordination for successful installation.
“Once again Perlo has proven they are the best in the business with their dedication and hard work on the GXO project. This project was not easy and Perlo achieved TCO quicker than anyone expected.”
Trammell Crow Company
Materials Lead Times
As is true on most projects in today’s climate, the GXO project experienced challenges with materials lead time, with the largest problem related to the tenant required back-up generator, electrical gear and Automatic Transfer Switch (ATS). The back-up generator, in particular, continued to be delayed, and despite consistent communication with the manufacturer, it became clear that the generator would not be onsite in time to open the building.
After months of communication between the manufacturer, ownership teams, jurisdiction, design team and electrician, it was determined that we could switch to battery backup systems in order to achieve substantial completion and still provide backup power for the facility. Once the generator arrives at some point in the future, the teams will coordinate to install the ATS and backup generator.
Additionally, the electrical gear was shipping and landed in a port in Washington State, but labor challenges meant that it would not be shipped from the port to our site for an unknown length of time. Our electrical trade partner, Current Electric, acted immediately, travelled to the port, loaded the gear, and delivered it to the jobsite. Following this, they worked over a weekend to install it and received approval the following Monday. These kinds of extra efforts from our loyal trade partners help projects succeed.
Underground Clay Tile Drainage
While the site was relatively uncomplicated, the Geo report suggested that clay tile drainage systems may be present, and our teams did indeed found them. To remedy this, the team used cameras to scope the tiles to determine the extent of their locations. The excavator then completed pot-holing to allow them to be filled with grout.
The GXO building is a testament to great project management and excellent onsite coordination despite of some less-than-ideal conditions and materials delays. The inclusion of higher-tech storage and fulfillment systems, as well as electric charging stations on the interior and exterior, help make this industrial facility anything but boring. We are grateful to the ownership, development and design teams, along with our Trade Partners, for their work with us.