The Problem with Drilling Into Manhole Covers
When installing monitoring equipment in sewer systems, it might seem convenient to drill directly into the manhole cover. After all, it’s right there—flat, accessible, and seemingly ideal. But this approach can lead to serious safety, operational, and regulatory issues. Here’s why you should avoid it—and what to do instead.
Manhole covers are engineered to meet strict load-bearing standards, such as EN 124 and ASTM A48, which ensure they can withstand heavy traffic and environmental stress. Drilling into them compromises their structural integrity, potentially leading to:
- Weakened load-bearing capacity, increasing the risk of cracking or collapse under vehicle weight.
- Ingress of water and debris, which can lead to corrosion, freeze-thaw damage, and sensor failure.
- Regulatory violations, as many municipalities prohibit modifications to standardized infrastructure components.
- Operational headaches, including misaligned covers, rattling, and increased maintenance costs.
According to guidance from the American Public Works Association (APWA) and Water Environment Federation (WEF), manhole covers should remain unaltered to preserve their safety and compliance characteristics.
A Better Alternative: Mounting to the Vault Wall
Instead of altering the manhole cover, mount your monitoring equipment to the interior wall of the vault—typically made of concrete or brick. These materials are far better suited for secure, long-term installations:
- Structural compatibility: Concrete and brick are designed to be drilled into. They provide a stable, vibration-resistant anchor point for mounting brackets and sensor hardware.
- Preserved cover integrity: By leaving the manhole cover untouched, you maintain its original strength and compliance with municipal standards.
- Improved sensor performance: Sidewall mounting allows for better positioning of antennas and sensors, especially in areas with poor cellular reception or heavy traffic above.
- Easier maintenance: Technicians can access and service equipment without disturbing the cover or risking misalignment.
Our Recommendation
Our mounting kits are specifically designed for vault-side installation. They include rugged hardware and detailed instructions for anchoring into concrete or brick, ensuring a secure fit without compromising the manhole structure. This method not only protects public infrastructure but also enhances the reliability and longevity of your monitoring system.