AN ANGRY ORPHAN GAS WELL OF CLEVELAND - INVESTIGATION TO REMEDIATION

Orphan gas wells are found across the Greater Cleveland area. Often, they are found beneath existing structures. In the event a structure is built over an active orphan well, the structure is immediately subject to intrusion of methane gas. Depending on the pressure and volume, a structure can fill with methane and other gases, creating unsafe conditions for occupants. In this case, a national bank unknowingly built a branch office over an active orphan gas well. The development was part of an overall site-wide brownfield project at a former steel mill. In accordance with site use limitations, several areas of soil and groundwater contamination remained.

Upon opening the branch office in 2012, there was gas detected in the building that caused immediate action. A vapor extraction system (VES) was built by a local consulting firm. The system included a vacuum blower, a 3’ deep 2” PVC extraction well, and a system to collect water designed to shut-off when the water barrel filled up. After 7 years of operation, the system proved faulty with too much water being drawn into the barrel and the system intermittently shutting down, allowing gas to seep into the building.

In 2019, RETTEW Associates, Inc. was contracted by the bank to evaluate the existing system and the conditions inside the building. It was discovered during records review that the gas in the building was due to the presence of an abandoned orphan gas well located beneath the men’s restroom. The history of the suspected gas well is unknown and there is no record of the well or the well being plugged by ODNR, Division of Oil & Gas. As such there is no record of well construction, depth, or operational history. There was no record of the well leaking or generating methane during construction.

After initial analysis, it was determined that 1) the vent stack was improperly constructed as vapors from the stack were getting circulated into the HVAC system and 2) the existing vapor mitigation system was insufficiently sized to prevent methane intrusion into the building. The new system included a new vacuum blower motor connected to a PVC manifold with perforated laterals extending under the building into the sub-slab plenum space, and a new vent.

Quarterly O&M is performed and the system has been successfully operating since 2019. A complete servicing and maintenance was necessary in Nov. 2024.