This project demonstrated a wireless remote-monitoring system for detecting and reporting steam leaks or flooding in underground heat-distribution system HDS manholes. The system immediately notifies maintenance personnel of critical conditions that could indicate expensive energy losses and potentially serious damage to the HDS. Demonstrated at Redstone Arsenal, AL, the system used durable temperature and water-level sensors for operating in very high heat and humidity. Remote-monitoring nodes included remote transmitting units using one of two alternate wireless data technologies. Wireless 900 MHz Ethernet service was installed and commissioned for eight manholes, linking them to the Redstone supervisory control and data acquisition SCADA system, but full integration with the SCADA system was not feasible given limitations on installation resources. Cellular data service was installed for six other manholes and commissioned successfully. Those nodes functioned for about 15 months to record ambient manhole conditions and email daily rollup data to the project point of contact POC, verifying continuous operation. The functionality of the system design was validated, but important lessons were learned about electric service availability, line-of sight antenna positioning for wireless Ethernet, and RTU installation. The return on investment for the cellular system was 94.6, potentially saving 534,000 in maintenance over 30 years.