What is a Manufactured Gas Plant (MGP)?
Prior to the widespread availability of natural gas, gas was “manufactured” through a process of heating coal in specialized ovens. These facilities, called Manufactured Gas Plants (MGP), were common in many urban areas of the United States during the late nineteenth and early twentieth centuries.
Manufactured gas was used for residential street lighting and cooking. The manufactured gas process produced by-products, such as coal tar and other chemicals that were also used in the chemical, dye, and pharmaceutical industries. An unintended consequence of the MGP industry was the effects of coal tar and various by-products on the environment.
Former Warren Street MGP
A predecessor company of PSE&G operated an MGP in Trenton from the late 1840s to late 1890s on four parcels east of Route 29. MGP operations ended in the late 1890s. The site subsequently served as a gas district operations headquarters facility from the late 1890s to the 1920s, when it was acquired through a series of transactions by the City of Trenton. Between 1960 and 1965, buildings were removed, and the site was then redeveloped.
This three-acre site, near the corner of South Warren and Market Streets (Block 10701, Lots 1, 2 and 3), is located on State of New Jersey property. It is currently composed of a portion of a large parking lot and adjacent to a helicopter pad near the Department of Labor and Division of Taxation buildings, and across the street from the Hughes Justice Complex.
Work Completed to Date
PSE&G has conducted extensive remedial investigations of the site in accordance with the regulations and oversight provided by the New Jersey Department of Environmental Protection (NJDEP). The investigation results were provided to the NJDEP for their review and approval in the late 2000s. The NJDEP Site Remediation Program Interest (PI) number for the site is G000005462 and the Activity #: LSRI120001.
A Remedial Action Work Plan (RAWP) describing the remediation method was submitted and approved by the NJDEP in March 2010. The remediation is being performed in accordance with the NJDEP Technical Requirements for Site Remediation, required regulatory agency permits and under the oversight of a Licensed Site Remediation Professional (LSRP).
In summer 2023, in preparation for remediation planned in 2024, soil sampling was performed to further refine the extent of the remediation and for waste classification purposes. Such sampling is a standard part of pre-design planning for the remediation of impacted soils.
Focus of Current Activities
Approximately 100,000 tons of MGP-impacted soil will be excavated. Any infrastructure related to the former MGP operations that remain underground also will be removed. The excavation of impacted soil will have a beneficial effect on groundwater, which will continue to be monitored following the soil remediation.
The majority of the work will be performed within a temporary sprung structure (i.e., tented enclosure). Excavated soil will be transported to a licensed off-site soil treatment facility. The remedial site will be backfilled with certified clean fill and restored to the pre-existing conditions. Groundwater encountered during soil remediation activities will be treated and conveyed off site in accordance with permitting.
The work is anticipated to take approximately 18 months to complete.
All activities are being completed in accordance with the NJDEP Technical Requirements for Site Remediation and under the oversight of the LSRP.