Underground fire protection rooms housed in metal tanks: These are often offered as “monoblock” systems that integrate a water storage tank, a pump room, and an access compartment. Before choosing or installing them, it’s worth taking a step back to assess the risks, obligations, and liabilities that arise as early as the design phase.*
Table of Contents
What Are “Monoblock” Underground Systems?
The fire protection market offers underground systems that integrate the following components within a single metal unit:
- water storage tank;
- pump room;
- entrance to the pump room.
Access is typically via stairs from ground level down to the pump room, which is often located at considerable depths (approximately between 3.5 and 4.0 m). This factor alone affects usability, management, and safety.
UNI 11292: When Underground Installation Is Permitted (and When It Is Not)
UNI 11292, in section 4.1.2, permits underground installation but sets a clear condition: The construction of underground rooms is not permitted in areas at risk of flooding or exposed to the risk of inundation in the event of severe weather, unless specific engineering measures are taken for the installation.
This approach leads to an operational consequence: any project involving an underground system should include an assessment of the project area, with the aim of ruling out the risk of flooding. In the absence of such an assessment, the construction of the structure is unlikely to be feasible.
Because it isn’t a “theoretical” risk
The report points out that a significant proportion of Italian municipalities are at risk of flooding and landslides; in light of this, the use of underground systems should be an exception rather than the “standard” choice.
From a practical standpoint, the critical issue is simple: the fire protection room can end up completely flooded, even in presence of safety systems designed to prevent it. This scenario is not only a systems-related problem but also becomes an issue of access, maintenance, and operator safety.
UNI EN 12845: Periodic access makes the room a “workplace”
UNI EN 12845 (Chapter 20 – Maintenance) stipulates that the pump room must be accessed at least once a week to perform inspections, checks, and maintenance.
This leads to a crucial point: the pump room effectively becomes a “workplace” and falls under the scope of Legislative Decree 81/2008, specifically Articles 65 and 66 (underground or semi-underground areas; work in environments suspected of contamination).
Confined Space: Why an Underground Metal Tank Exacerbates the Hazards
Therefore, Presidential Decree 177/2011 and the ISPESL Operational Guide dated June 12, 2008, apply to the facility. The latter (citing Article 66 of Decree-Law 81/2008) introduces the definition of “confined space”: a confined space with limited access openings and inadequate natural ventilation, in which a significant incident could occur, potentially resulting in a serious or fatal injury.
In integrated underground metal systems, natural ventilation is described as extremely poor (practically nonexistent). In addition, several hazards are cited, including:
- electrical hazards (loss of insulation; direct contact facilitated by confined spaces);
- chemical hazards (hydrogen produced by batteries; fuel vapors from leaks during diesel refueling);
- risk of falling (open staircases, possible ice, snow, leaves);
- slippery conditions/contamination (traces of fuel and lubricating oil; condensation on walls and metal parts);
- amplification of the noise generated by the machines inside the metal tank.
In this context, access is not merely “inconvenient”; it can become inherently critical, especially since one may be forced to enter even in emergency situations.
“Easy Access” and Emergency Response: The Critical Issue Regarding UNI 11292
UNI 11292 (section 4.1) requires that the location of the room ensure that rescue teams can easily access it in the event of a fire.
The note questions whether the systems described can be considered “easily accessible” locations, and also highlights the other side of the issue: operations and maintenance personnel must be able to work in a safe environment. If the provisions cited are applied, access would in fact be limited to qualified and trained personnel.
Liability and SCIA: What Has Changed Under Presidential Decree No. 151/2011
Under Presidential Decree No. 151 of August 1, 2011 (new regulations governing fire prevention procedures), the responsibilities of the designer and the business owner are described as having been expanded.
The introduction of the SCIA (certified notification of commencement of work for fire safety purposes) requires the issuance of a certificate of compliance, in which the contractor certifies that the work complies with fire prevention regulations based on documentation, on-site inspections/verifications, and certifications.
The note also outlines the consequences of making false statements or misrepresenting documents, citing references (including Law No. 241/90, Legislative Decree No. 139/06, Articles 359 and 481 of the Italian Criminal Code, Presidential Decree No. 445/2000 ). This leads to a practical message: to reduce exposure to risks and disputes, the utmost care must be taken in selecting and verifying materials, checking certificates, and overseeing the work of installers, who share responsibility for compliance with regulations.
Which alternatives are identified as the “correct” choice?
With regard to underground fire protection rooms constructed inside metal tanks, the conclusion highlights that, in addition to the proper application of technical fire safety standards, it is necessary to apply, first and foremost, Legislative Decree 81/2008, which is cited as a definitive reference in court proceedings in the event of an adverse incident.
The preferred approach involves solutions that avoid having the pump room located underground in a metal tank:
- an outdoor water station next to the storage tank (with horizontal centrifugal pumps); or
- In-ground pool with an outdoor pump station (equipped with vertical turbine pumps).
In both cases, the downstream hydraulic configuration is specified as the only one capable of ensuring that the design flow rates (Q/H) are available at all times.
Conclusion
Choosing underground fire suppression systems housed in metal tanks—such as integrated underground systems—means taking on a significant burden of responsibility and addressing concrete issues related to safety, access, and management. If maintenance requires periodic access and the room becomes a workplace, the assessment must include risks of flooding and conditions similar to those of a confined space, in addition to obligations related to the SCIA and reporting responsibilities.
