This paper proposes an IoT-enabled network of low-cost sensors that are co-located for construction site monitoring. The network performance enhancement is achieved via its system dependability in terms of improved availability, integrity, reliability, maintainability, security and safety in real-time monitoring of environment parameters. The sensor motes of various sensing modules form a reliable wireless in-situ cluster for gathering on-site information of air temperature, soil moisture, air pressure, humidity, particulate matters (PM), emissions and weather variables. They are useful for the site management, improving safety and effective operation of construction equipment. The components for the development include inexpensive microcontrollers ESP32 embedded with wireless gateway function and energy-efficient motes featuring cost-effective sensors. Here, the adoption of the dependability concept for collocated sensor motes aims to introduce a level of redundancy to allow for improving fault-tolerance and reliability. Extensive field tests have been conducted in different environments. Experimental results as well as statistical analysis are provided to verify the merits of the proposed approach.