IoT Smart Manhole Cover Monitor with Displacement and Gas Alerts

Open or displaced manhole covers cause fatal accidents every year, and sewer gas build-up — methane and hydrogen sulfide — kills sanitation workers silently. Municipal monitoring of covers is practically nonexistent in most Indian cities: inspections are manual and infrequent. This project builds the missing sensing layer as a student-buildable prototype: a ruggedized monitor box that bolts to the underside of a manhole cover, detects tilt/displacement with an accelerometer or tilt switch, sniffs gases with MQ-series sensors, and reports over Wi-Fi with a local buzzer and LCD for on-site status. The engineering substance is in the threshold logic — distinguishing a real gas hazard from sensor drift, and a real cover movement from vibration — plus the low-power design thinking for a device that must live underground.

1. The monitor unit is fixed to the underside of the manhole cover; on power-up the gas sensors warm up and the ESP32 establishes a baseline reading.
2. An accelerometer/tilt switch continuously watches the cover's orientation; gas sensors are sampled on a schedule between low-power sleeps.
3. When tilt exceeds the configured threshold (cover opened or displaced) the buzzer sounds, the LCD flags COVER OPEN, and a displacement alert with the cover's location tag is pushed over Wi-Fi.
4. When methane or H2S readings cross their alert thresholds for a confirmed duration, a gas-hazard alert is raised the same way, with the measured levels included.
5. All events — displacements, gas alerts, sensor baselines — are logged with timestamps to the monitoring endpoint for the dashboard view.
6. On site, the LCD shows live gas levels and cover status so maintenance crews can read conditions without opening the cover.

Tech stack:

• ESP32 (firmware, Wi-Fi, sensor reading, alert logic)
• MQ-4 methane sensor, MQ-136 hydrogen sulfide sensor
• Tilt switch / accelerometer (displacement sensing)
• 16×2 LCD, buzzer (local indication)
• Arduino framework firmware
• HTTP/MQTT alert endpoint + event log dashboard
• IP-rated enclosure, battery + solar-charging provision

• [Displacement detection] Tilt/shock sensing on the cover: opening, tilting beyond the threshold angle, or shock from impact raises an immediate alert.
• [Sewer gas sensing] MQ-4 (methane) and MQ-136 (hydrogen sulfide) sensors with calibrated alert thresholds; the firmware distinguishes genuine build-up from warm-up drift.
• [Local alarm] Buzzer plus 16×2 LCD showing live gas readings and cover status for on-site inspection.
• [Wi-Fi alerts] ESP32 pushes displacement and gas alerts with device ID and location tag to the monitoring endpoint; events are logged with timestamps.
• [Battery-aware design] Sleep scheduling between readings and solar-charging provision documented for long field deployment thinking.
• [Buyer-run calibration procedure] Step-by-step sensor warm-up, baseline and threshold-setting procedure the buyer performs on their own build — no invented "measured" figures.
• [Enclosure & mounting design] IP-rated enclosure concept and under-cover mounting arrangement documented in the build guide.

• Assembled monitor prototype (ESP32, sensors, LCD, buzzer, enclosure)
• Complete firmware source with threshold logic and alert code
• Wiring diagrams and bill of materials with exact part numbers
• Buyer-run calibration & threshold-setting procedure
• Mounting and enclosure design documentation
• Project report PDF (background, sensor theory, system design, firmware logic, testing procedure)
• PPT presentation for final review
• Viva Q&A preparation document (MQ sensor chemistry, calibration, power budgeting, threshold design)

• Gas readings are indicative, not laboratory-grade: MQ sensors drift with temperature and humidity, which is why the calibration procedure is part of the deliverable.
• Alert thresholds are design targets set during the buyer's own calibration — no measured detection figures are claimed before that run.
• Wi-Fi range limits underground deployment; the enclosure sits near the surface and LoRa is documented as the upgrade path (future scope).
• Battery life depends on sampling schedule and solar input; the report gives the power-budget calculation rather than a measured endurance figure.
• This is a hazard-indication prototype, not certified safety equipment.