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Mijnwater starts drilling for new heat source on Terhoevenderweg in Heerlen
New source expands Parkstad’s district heating and cooling network
Mijnwater has started drilling work for a new heat source at Terhoevenderweg in Heerlen, marking another important step in the expansion of its sustainable heating and cooling network in Parkstad. After a period of preparation, work began this week and is expected to continue for three to four weeks. Because the operation must be completed safely and efficiently, the drilling is taking place 24 hours a day, seven days a week.
The project is part of Mijnwater’s broader effort to strengthen a low-carbon energy system for the region. The new source will tap warm groundwater in a former mine passage deep underground and feed that energy into the company’s network. For Heerlen and the surrounding area, this means further development of a district energy system that draws value from the region’s mining past while supporting a more sustainable energy future.
People driving past the site have likely already noticed the large drilling rig and the noise barriers placed alongside the road. These are the most visible signs of a project that is both technical and locally significant. On the one hand, it is an engineering operation involving deep drilling and groundwater access. On the other hand, it is a regional infrastructure investment with implications for housing, public buildings, and commercial premises that will benefit from the extra thermal capacity.
Why the Terhoevenderweg site matters
The new source at Terhoevenderweg is designed to reach a former mine gallery at a depth of approximately 634 meters. At that depth, warm groundwater is present in the old workings of the mine. Mijnwater will use that water as a sustainable source for heating and cooling buildings in the area. The project is a reminder that subsurface infrastructure from the mining era can still play a role in the modern energy transition.
According to Mijnwater, the groundwater in the mine passage has a natural temperature of about 28°C. That is warm enough to be highly useful in a district energy system, particularly when combined with heat pumps and heat-exchange equipment. While the temperature may not seem high compared with traditional heating systems, the real advantage lies in the ability to recover thermal energy consistently and distribute it efficiently to many users.
This is not Mijnwater’s first project of this kind. The company already operates thermal sources that feed its system, and this new location becomes the fourth warm source in its portfolio. That makes the Terhoevenderweg drilling more than a standalone project; it is part of the gradual expansion of a network that is becoming increasingly important to regional energy supply.
The fact that the source is located in the former Oranje-Nassau III mine also gives the project a strong historical dimension. Oranje-Nassau III was once the deepest of the Oranje Nassau mines, which were central to Limburg’s industrial development. Today, the same underground structures are being repurposed for a different kind of public value. Instead of coal extraction, the site is now tied to a cleaner, more flexible energy system.
From mine legacy to modern heat supply
The transformation of old mine workings into energy infrastructure is one of the most distinctive features of Mijnwater’s model. Limburg’s mining heritage created deep underground cavities, access points, and water-filled passages that can now be used for thermal applications. In this sense, the region’s industrial past is not just being preserved in memory; it is being converted into practical energy infrastructure.
The concept is especially relevant in a region like Heerlen, where the challenge is not only to generate sustainable energy but also to build a system that fits local conditions. Mine water offers a local resource that would otherwise remain underused. By connecting that resource to a network of pipes, pumps, exchangers, and controls, Mijnwater can distribute usable heat and cold to multiple buildings while reducing dependence on fossil fuels.
This is one reason the project has drawn attention beyond the immediate neighborhood. It shows how former industrial land can be integrated into climate-oriented infrastructure without relying on large new land take or distant energy imports. Instead, the region builds on what already exists underground. The result is a highly place-based approach to energy transition that is both technically interesting and symbolically powerful.
The Terhoevenderweg source also strengthens the logic of district heating and cooling in urban and semi-urban settings. Unlike isolated heat pumps in individual buildings, a networked system can serve many customers from shared infrastructure. That can improve efficiency, reduce duplication, and make it easier to manage renewable thermal resources over time. Each additional source adds flexibility, resilience, and reach.
How the drilling works
The current phase of the project focuses on reaching the mine passage through deep drilling. The borehole will extend to about 634 meters, where the former mine gallery contains the warm groundwater Mijnwater intends to use. The drilling campaign is expected to take between three and four weeks, depending on conditions underground and the progress of the work.
Because the project is being executed around the clock, it requires careful coordination. Continuous work can improve efficiency and shorten the overall construction period, but it also demands strong control over safety, noise, and logistics. For that reason, Mijnwater has installed noise barriers and organized the site to reduce unnecessary disruption as much as possible.
Deep drilling in an urban or peri-urban setting is always a sensitive operation. Heavy equipment, transport movements, and sustained activity can affect nearby residents and road users. In this case, the company is clearly aware of that challenge and has stated that it is taking measures to limit the impact. The visible barriers around the site are only one part of that effort; the way the work is planned and monitored is equally important.
Once the borehole reaches the target depth, the system can access the groundwater in the old mine passage. From there, the water can be brought to the surface and incorporated into Mijnwater’s broader network. The technical success of the project will depend not just on drilling, but also on how well the new source integrates into the existing infrastructure.
The role of 28°C groundwater
A temperature of around 28°C may sound modest, but in district energy terms it is a valuable resource. Warm water at this level can be captured and upgraded through the right system design. Often, low-temperature heat sources are paired with heat pumps, which raise the temperature to a level suitable for heating homes, offices, schools, or public facilities. That makes the source useful even if it is not hot enough for direct use on its own.
Low-temperature thermal systems are increasingly attractive because they can be efficient, local, and compatible with renewable power. They also support heating and cooling in one integrated network, which is especially important in areas where the demand for both is significant. In summer, the same network can help remove heat from buildings and move it into the subsurface or another part of the system. In winter, the stored or recovered heat can be used to meet heating demand.
This flexibility is a major part of the appeal of Mijnwater’s model. Rather than relying on one high-temperature source, the company can use a mix of thermal inputs and networked energy flows. That makes the system more adaptable and potentially more resilient over the long term. The Terhoevenderweg source adds to that adaptability by bringing new capacity online in a strategically useful part of the network.
The planned output of around 240 cubic metres of warm water per hour suggests that the source will be a meaningful contributor. The exact impact will depend on how it is operated and how the energy is distributed, but the volume points to substantial potential. When this amount of water is captured and managed efficiently, it can support a significant share of heating and cooling demand in the connected area.
A fourth warm source for Mijnwater
This project will become Mijnwater’s fourth warm source, which is an important milestone for the company. Each source increases the size and robustness of the district network. It also shows that the model is not confined to a single experiment but is being expanded step by step. In infrastructure terms, that kind of scaling matters because it demonstrates both technical continuity and operational confidence.
A network with multiple sources can better balance supply and demand. If one source is under maintenance or operating below capacity, another can help compensate. That makes the overall system more reliable for customers. It also allows the operator to manage energy flows more intelligently, depending on seasonal conditions, building demand, and network performance.
The addition of a fourth warm source also signals that Mijnwater is continuing to invest in the long-term development of the system. District energy networks require patience, capital, and a clear understanding of local needs. They do not expand overnight. Instead, they grow through a series of connected projects, each of which adds value to the whole. Terhoevenderweg is one of those projects.
This latest source may also encourage further confidence in the role of mine-water systems in the energy transition. Heerlen has become a reference point for this type of infrastructure because it combines historical geography with modern climate strategy. As more regions look for alternatives to fossil-based heating, the experience in Parkstad could become increasingly relevant.
Community impact and local concerns
Any project of this kind affects the surrounding environment, even when the long-term benefits are positive. Residents near the site may experience noise, temporary traffic disruption, and visible construction activity. Mijnwater has acknowledged that such inconvenience may occur and has said it is trying to minimize the impact through protective measures and careful planning.
The company has installed noise barriers along the road to reduce disturbance from the drilling operation. That is a practical step, especially when heavy machinery is operating day and night. But mitigation is not only about physical barriers. It also depends on communication, predictability, and a willingness to respond to local concerns quickly.
To that end, Mijnwater has provided a 24/7 customer service contact number for questions or complaints during the works. Residents can reach the company at 045 – 202 02 10 at any time. The company also lists klantenservice@mijnwater.com as a point of contact. That kind of accessibility matters because it helps create a direct channel between the project team and the community living nearby.
Infrastructure projects often succeed or fail partly on the quality of that relationship. Even when the project serves a broader public purpose, nearby residents judge it by how it affects daily life. Noise, sleep disruption, dust, and traffic are all immediate issues. By setting up round-the-clock communication and trying to reduce the most visible nuisances, Mijnwater is attempting to keep the balance between project delivery and local acceptance.
The broader Parkstad energy picture
The new heat source should also be understood in the context of Parkstad’s wider energy strategy. Like many regions across Europe, Parkstad is looking for practical ways to reduce carbon emissions while keeping energy supply reliable and affordable. District heating and cooling networks are one of the most effective tools for doing that in built-up areas, especially when they can draw on local thermal resources.
Mijnwater’s system is particularly interesting because it uses a resource that emerged from the mining era rather than a newly drilled deep geothermal field. That makes the project locally distinctive and potentially easier to integrate into the area’s existing urban fabric. It also shows that energy transition does not always mean building entirely new systems from scratch. Sometimes it means adapting and reusing the infrastructure, geology, and spatial patterns already present.
In the case of Heerlen, the connection between former mines and present-day thermal supply is especially compelling. The city and surrounding region have a long industrial history, but the mine landscape is now being repositioned as part of the solution to future energy needs. That shift carries symbolic weight. It suggests continuity between economic history and climate policy, between local identity and technical innovation.
Projects like Terhoevenderweg also support energy security. Local heat sources reduce dependence on imported fuels and can help stabilize long-term costs. Because district systems are centralized, they can also be managed more strategically than a patchwork of individual heating solutions. That can benefit both users and operators over time, especially as energy prices and regulations continue to evolve.
Looking ahead
The coming weeks will be decisive for the project. If drilling proceeds as planned, Mijnwater will be able to complete the borehole and move closer to integrating the new source into its network. The immediate focus is on safe execution, technical success, and minimizing disruption. The longer-term focus is on how the source performs as part of a growing district energy system.
If the project delivers as expected, it will strengthen Mijnwater’s ability to supply sustainable heating and cooling in Heerlen and beyond. It will also reinforce the idea that old mine workings can be part of a modern climate strategy. That matters not only for Parkstad but for other post-industrial regions searching for workable models of energy transition.
The Terhoevenderweg drilling campaign is therefore more than a site-specific construction effort. It is a practical test of how historical underground assets can support future energy needs. It is also another step in the steady expansion of a network that already plays a visible role in the region’s energy landscape. If successful, this fourth warm source will become an important part of Mijnwater’s growing system.
Conclusion
Mijnwater’s drilling work at Terhoevenderweg in Heerlen marks a significant development for the company’s sustainable heating and cooling network. By targeting a former mine passage at 634 meters depth and tapping groundwater at about 28°C, the project transforms an old mining structure into a modern energy source. The source is expected to provide around 240 cubic metres of warm water per hour and become Mijnwater’s fourth warm source.
The project also demonstrates how local history, engineering, and climate goals can come together in one infrastructure plan. While nearby residents may experience temporary inconvenience during the drilling phase, Mijnwater says it is taking measures to reduce the impact and remain available around the clock for questions. If the project proceeds successfully, it will not only expand the Parkstad network but also strengthen the case for mine-water energy systems as a practical part of the broader energy transition.
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