We have recently received a lot of questions about one of our most visible projects located at the corner of Tualatin Sherwood Road and 124th in Tualatin, Oregon. That question is a resounding, ‘what is that large rock pile for?’ The simple answer is that this temporary mountain of crushed rock is a result of a mining operation to flatten a site that had 60’ of elevation change prior to the work beginning. Today we’ll explore beyond the large rock pile and provide an overview of the work taking place at Tualatin Sherwood Corporate Park (TS Corporate Park). This 32-acre development is striving for LEED certification and will be home to three speculative industrial buildings with a completion date in early 2022.
The Tualatin Sherwood Corporate Park Development
This full site development includes three new industrial buildings with all associated site-work and public street improvements. The three finished structures will include:
Building C: 271,581 sf concrete tilt-up shell
Building D: 145,624 sf concrete tilt-up shell
Building E: 62,212 sf concrete tilt-up shell
Each building is of concrete tilt-up construction with dock doors, drive-in doors, concrete interior slabs, ample parking and semi-truck traffic routes. Built on a speculative basis, these are currently available to lease through Jones Lang LaSalle (JLL) and Macadam Forbes.
The Excavation and Mining Work
To level the site, excavating company Kerr Contractors is completing more than 1 million cubic yards of excavation work, including the blasting and mining of nearly 600,000 cubic yards of rock. The visible rock stockpile is made up of roughly 1/3 of that yardage, with the prior 1/3 already consumed by off-site locations, and about 1/3 left to be mined and relocated.
Of the crushed rock generated on the site, about 60,000 cubic yards have been used or will soon be utilized for building foundations, parking lot subgrades and the public access improvements to extend Cipole Road into the site. The remainder will be used for other jobsites that Perlo and/or Kerr Contractors is completing or sold for consumption by other contractors off-site.
To accomplish the large rock removal operation, a concrete crusher was installed onsite with a weigh-station so that rock can be crushed, stored, then loaded, weighed, and sold directly from the TS Corporate Park site. At completion, the crushing operation will be dismantled and removed.
The mining operation has consisted of blasting at least once weekly since the work began. The largest blasting work has been completed previously, with more surgical blasting and mining continuing from now until nearly the end of the year to round out that scope of work.
To complicate the mining operation, the construction of the new concrete tilt-up structures began long before the blasting work was planned to finish. To accommodate the concrete pours, Perlo and Kerr teams have regularly coordinated to prevent damage to the new concrete. Some strategies to avoid concrete damage include:
- Timing blasting to avoid vibration within at least 7 days of any concrete pour. This may require blasting twice in lieu of once so that rock crushing operations can be maintained while concrete is poured and cures.
- The installation of vibration sensors in the ground to track movement due to blasting and ensure that vibration levels are low enough to maintain the integrity of the building structures.
The mining operation is running 7 days per week and 24 hours per day to maintain the owner’s desired schedule. Permitting took place through the City of Sherwood, as well as Tualatin Valley Fire and Rescue to ensure that communication and safety between the local areas and the site are well planned and maintained. So why is there such a large pile of rock? Quite simply, the mining and crushing is taking place faster than the rock can be sold and consumed off-site. We anticipate that all the rock will be removed by year-end. Until then, we watch it grow, change, and soon be minimized to a level site.
Site Utility Tie-ins
Previously undeveloped, the site needed all new power, water, storm and sewer systems to be installed. Logistically, tying these utilities into the site has been one of the challenges of the work. The new sewer line, for instance, had to be tied into the existing city sewer system located across Oregon street at the Western corner of the site. The 12” pipe had to run very near to a local dental office, with boring under Oregon street to be completed. In addition to standard utility connections for the buildings, the development will include several new electric vehicle charging stations, complete with the infrastructure to provide adequate power to these units.
Unique Site Features
Aside from the significant excavation work, the site includes some unique features:
- A soil nail shotcrete retaining wall that is 15’ tall at its highest point.
- A natural rock wall adjacent to the shotcrete wall where the primary rock mining work is taking place. This wall is 40’ at it’s highest point.
- A new street extension to bring Cipole road into the site, complete with a new streetlight.
- Significant lengths of lock + load retaining walls near the street.
- Large onsite water retention ponds for stormwater management.
- Electric vehicle charging stations.
Critical Site Logistics
The presence of more than 75 trade workers and truck drivers each day means that site safety and clear logistics planning are critical to delivering a successful project. Though the site is quite large, much of it has been taken up by the mining operation and storage of rock. Additionally, there is the construction of three buildings, sitework, and the trucking needed to export the rock all taking place at the same time. These factors make for a logistical challenge that has taken expertise and extensive communication to overcome.
Some of the strategies we are using to ensure the safety and efficiency of the site include:
- Amy Cook, a full time safety team member on the site to help maintain a safe construction site.
- Regular site meetings with all subcontractors involved are held to maintain communication and coordination.
- Clear signage and traffic routes onsite.
- Pre-determined materials laydown areas and crew parking locations.
- Extensive pre-planning and routine reviews and updates to that plan as the work progresses.
Extensive communications protocols, pre-planning and some creativity have led to a safe, clean and organized site.
All three buildings are aiming for LEED certification at completion. Some strategies used to attain this certification include minimizing contaminants in all building materials, and sourcing local materials. Additional measures for LEED certification will take place for the tenant improvement work when the spaces are leased to a tenant.
The TS Corporate project has been a shining example of complex site logistics and communications strategies. As one of our more publicly visible sites, it has been an honor to have the opportunity to talk to so many community members about the work being completed there. We look forward to completing the project this Fall.
If you’d like to know more about our construction services or want to get in touch, please visit our services page or contact us here.