Mountain Hall Expansion at DC1-Stavanger
Green Mountain
New Design/Build Data Centre Project Of The Year
Entry Description
Less than 8 months after Green Mountain expanded its mountain hall facility at DC1-Stavanger, the company completed yet another 2.5 MW expansion at this facility in May 2021. The expansion is a Tier III built-to-suit project for a large international cloud provider.

Building inside a mountain is undoubtedly a more complex challenge compared to an open-air construction site, and the Covid-19 situation added an extra layer of complexity. This forced the design and project team to rethink their procedures, and be innovative in their approach to designing this mountain hall expansion. Since space is a limiting factor inside a mountain, the design had to be extremely compact. The cooling solution in particular required innovative customization and product development to achieve optimal efficiency and fit the space requirements. In addition, this build was to be completed in an already live data hall in the same mountain hall, and the team had to take specific precautions not to interfere with the existing operation.

In other words, the main challenges in this project related to:
• Strict deadline and Covid-19 situation.
• Building inside a mountain as opposed to an open-air construction site where you have more space flexibility.
• Need for customized cooling .
• Constructions in an operational environment.

How did we overcome these challenges?

Strict deadline and Covic-19 situation:
The team was convened for planning and design during the proposal and negotiation phase with the client. Next, the contract was signed in Fall 2020 with an agreed RFS date of June 1st, 2021. The team knew it was a tight deadline, even without a pandemic, and immediately started to execute their project plans to secure progression and avoid delays.
One key decision was to order equipment very early in the process, even before all the details were sorted. Especially concerning “long lead items”, the team made sure to book time in the production line of the suppliers. This way they secured a “buffer” in case of unforeseen events. This proved to be valuable when large parts of society were affected by the Covid-19 situation. Because of the meticulous planning and cooperation with partners, the team benefitted from a head-start in the process. They could also draw on the experience they had from the previous expansion in the months prior.
Furthermore, the team had a very progressive approach towards the suppliers, with close follow-ups to make sure deliveries were prioritized. Not only did the lead project manager and procurement manager constantly address the suppliers, but this was also escalated to top management to secure the necessary attention.

Building inside a mountain:
The location of this build was at DC1-Stavanger, Green Mountain’s data center site on the west coast of Norway. This former NATO ammunition storage facility, deep inside the mountain, has been converted into several Tier III certified data halls. The capacity of the site has not yet been fully exploited and this project was an expansion build for an existing client already located in two of the data halls.
In Fall 2020, the initial expansion was completed. At that time, the starting point was an empty mountain hall with no basic infrastructure. This space was then transformed into a fully operational data center space, complete with interiors, cooling, security and supporting a power capacity of 2.5 MW. Now, in this new project, our task was to expand this data hall, which was in full operation. Adding another 2.5 MW capacity and thereby reaching the full capacity of both space and power in the mountain hall.
The size of the fully completed mountain hall, including infrastructure in the tunnels, is about 1800 square meters. The full power capacity is now 5 MW. Running on 100% renewable hydropower and cooled by water from the adjacent fjord, it is also one of the greenest data centers in the world.
For cooling, down flow units were used instead of in-row cooling according to customer requirements. This was also a more cost-efficient solution. The cooling source is the adjacent fjord, where our award-winning cooling solution supplies 100 kW of cooling for every 1kW of power used to operate the system. Designing the cooling solution to fit within the mountain's size limitations was one of the biggest challenges in this project.
Having a data center inside a mountain naturally implies that this is a high-security facility. The facility can withstand attacks and natural disasters (although very rare in Norway), but the client also had strict requirements of numerous high-security measures. Designing and implementing this security regime was a significant part of the project.
As mentioned earlier, building inside a mountain imposes restrictions when it comes to space. In the design phase we had to know the exact measurements of all components to make sure they would fit into the allocated space. There was not an option to expand the area. As a result, we designed a very compact installation. The infrastructure rooms were optimized to obtain sufficient space, cooling and airflow.

Need for customized cooling:
One of the main challenges in this project was to obtain the necessary cooling capacity. Traditionally, we would have chosen larger cooling units, but space restrictions did not allow us to do so. Consequently, we had to find a solution where smaller cooling units could provide the same capacity. Together with our vendor, Vertiv, we explored different ways to customize a standard CHRA-unit to perform better than the size normally would allow. The equipment was modified significantly, adding directional flaps, extra air plenum, stronger fans, different controllers and so forth.
Extensive testing was performed at the factory to make sure the units delivered the required cooling. However, you can never be certain of the result before you test it in the actual environment. A technical lab is never the same as the real-life environment. Consequently, we also did several on-site tests to verify the performance. After some adjustments, we concluded that the solution was fit for operation. Design & Product Manager, Alexander de Flon Ronning, describes this phase as a "mini product development project". "We were truly dependent on finding cooling equipment that would comply with the size restrictions and still deliver the required and reliable capacity. The cooperation with Vertiv on customizing the cooling units was a critical element in the project. I am very pleased that we managed to be innovative in finding a solution."

Constructions in an operational environment:
Another major challenge with this project was of course that we had to do the construction work adjacent to a data hall in full operation before connecting the two data halls together at the end. It was important that the ongoing operations were not disturbed in any way while we still kept up the pace to reach the RFS deadline.
Finding a way to move goods and people around in this environment efficiently and securely was therefore one of the concerns raised at the beginning of the project. The solution was simple yet efficient. We designed and built a special passage for workers and goods deliveries. This passage gave access to the construction areas while at the same time protected the operational areas. This also meant that we avoided some of the security procedures that otherwise would have been very
inefficient. Moreover, the passage and other protection measures prevented disturbance from dust, heat, vibrations, and sound to reach the operational area.

More aout the project:
The construction is made of concrete to preserve strength and anchor bolts of 3 meters secures the mountain walls. When building inside the mountain, the mountain sets the prerequisites of how we can build. The benefit is that this data hall is extremely secure, solid and will last at least 50 years. On the other hand, it also poses specific challenges, especially concerning space issues. If something at a later stage in the project does not fit, you can not just blast out some more room. The design must be accurate from the start and leaves little room for flexibility along the way.

A special circumstance for this project was of course the Covid-19 situation. As described earlier in this document, it affected how we worked to keep the progression and deadline. Another Covid-19 challenge the team had to overcome was how to conduct the CX commissioning and RFS without compromising Covid-19 infection control procedures. Representatives from the client and CX agents from BVPI* could not be physically present at the site. The solution was to perform the process remotely using virtual tools. During the test phase, the CX agents worked remotely through our on-site resources who were available by live video and Teams meetings to perform the tests. This method actually proved to be more successful than anticipated and more efficient for all parties involved. Given the situation, we shortened this phase by several days. It is also worth mentioning that performing load bank tests on a data hall inside a mountain is a bit more comprehensive than usual. It required 22 cables of 125mm, resulting in more than 6 km of cables in use during the tests.
*(company responsible for testing)

During the most hectic construction phase, 150 workers were on site, managing to perform their tasks within a strict Covid-19 control regime. A Covid-19 task force had daily meetings to monitor the situation and decided to implement personnel control at the gate. Each and every person had to answer specific questions and have their identity and access level verified upon every site entry. The result: no cases of infection on site or other HSEQ incidents during the project for that matter.

As mentioned earlier the timeline for the project was strict, even without a pandemic situation. Normally, a construction project like this would require 12 months, compared to the 6 months of construction that we planned. Important milestones were the completion of the data floor, power supply and “early access”. The data floor was a critical item in the timeline as a prerequisite for other tasks moving forward. The same goes for power supply, which was the milestone following the completion of construction and infrastructure works. In this phase we actually rewired the power supply so that the entire data hall (both the expansion and the 2.5 MW hall that was already in operation) would have three separate power feeds. Changing from a 2N solution to a N + 1 solution with three UPS’s to support the full 5MW solution. The operation was planned carefully, and we did the switch in a live environment with no downtime.

Most of our vendors and labor were locally sourced. Within a radius of 20 km of the site we could find most of the materials and workers needed, so this project gave positive ripple effects in the local community as well.

To summarize the project let us repeat the main points:
- 2,5 MW expansion inside a mountain
- Construction time: 6 months
- Built in concrete and with a very compact design to fit space limitations, including custom made cooling equipment
- Built adjacent to an operational data hall and then connected to complete a full 5MW data hall for an international cloud provider.
- The Covid-19 situation added an extra layer of complexity

So, what made this construction project special? In our opinion, it was the ability to deliver on our commitment to the client, despite the challenging circumstances.
By being a smaller organization, with only a handful of key project members, Green Mountain was nimble and adaptable to changing circumstances. At the same time, our solid project methodology and 10 years of experience with demanding international clients made us competent to execute complex projects. No doubt, there were challenging times in this project, but every employee tried to live up to the company values of “Customer in focus, Reliability & Honesty, Knowledge and Enthusiasm.” These values make up the foundation of our work culture and make the team go an extra mile to satisfy the customer.

The client’s representatives were impressed by the process and professionality, despite the threats Covid-19 posed to the project delivery. In fact, the Green Mountain team delivered the construction project 2 weeks ahead of schedule and a satisfied client could take over the fully extended 5MW data center after a 6-month construction process.
Supporting Documents