Below is a list of frequently asked questions about the environmental remediation of the former Harrison MGP site. FAQs are updated periodically based on questions received from the public, including questions posed during the December 2020, April 2021 and November 2021 webinars.

 Updated March 23, 2022

What was a Manufactured Gas Plant (MGP)?

Prior to the widespread availability of natural gas, gas was “manufactured” by 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 19th and early 20th centuries.  Manufactured gas was used for residential and street lighting and cooking. The manufactured gas process produced byproducts, 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 from coal tar and various by-products on the environment.

Who do I call if I have a concern?

If you have a question, we encourage you to call the Project Information Line at (855) 356-2383 or email the team at comments@HarrisonMGP.com. Kelly Henry is the community liaison working on behalf of PSE&G for the project and will respond to your call or email.

About the Site Remediation

What was the extent of impacts remediated? 

The entire 32-acre Site housed the former manufactured gas plant and related operations. As a result, the impacts extended across a substantial portion of the Site. The impacts to soils were remediated in phases between 2004-2018 and in 2020-2021. The current remediation project was completed in December 2021 and restoration was completed in Quarter 1 of 2022.

What constituents were the focus of the remediation?

The source of the MGP materials was the former MGP operations. The focus of the completed remediation were compounds from coal tar and oils, and included benzene, toluene, ethylbenzene and xylene(s) (or BTEX), naphthalene, and polycyclic aromatic hydrocarbons (or PAHs). 

Was any remediation work performed before the current phase of work?

Yes. Since 1999, PSE&G has installed and sampled regularly more than 60 onsite and off-site monitoring wells to determine the MGP impacts to groundwater. At PSE&G’s request, NJDEP first authorized in 2001 and then updated in 2002 a Classification Exception Area (CEA) and Well Restriction Area (WRA) for the entire Site. The CEA identifies where groundwater does not comply with NJDEP standards. A WRA restricts the use of groundwater in a CEA for potable use.

PSE&G performed Interim Remediation Actions (IRMs) to address impacts to soils in 2004-2008, 2006, 2009 and 2011. The remedial actions included a River Front Remediation conducted between the Site and the Passaic River to address migration of Site constituents in the overburden. In 2018, a pilot project, focused on remediating 1.8 acres of the 32-acre site, was successfully completed.

What is the current project?

The current project addressed impacts to soils that remained on site and was successfully completed in December 2021. Restoration work was completed in Quarter 1, 2022.

The Harrison former MGP Site was addressed with a combination of different remedies, including soil removal, soil containment and the treatment of soils in place, referred to as In Situ Stabilization Solidification (ISS).

Seven onsite buildings were removed to remediate the soil beneath them.  A hydraulic barrier wall and environmental cap were installed around the M&R station to contain impacted soils, and surface soils in the station were removed and replaced. Natural gas pipelines to the M&R station were replaced in 2021 in a clean utility corridor.

Restoration work included security fencing, repaving onsite roadways, and sidewalk repair. Remediated areas were backfilled with clean fill and clean stone to grade.

What is In Situ Stabilization Solidification (ISS)?

It is a proven environmental remediation process that involves mixing of contaminated soil in place with stabilizing agents, such as Portland cement and blast furnace slag. It solidifies the soil below ground.

What is a Hydraulic Barrier Wall?

Impacted soils near the active M&R Station and its infrastructure are remaining in place but contained through installation of a hydraulic barrier wall. Using special machinery, soil and bentonite were mixed in place down to depths of 60-100 feet to create the wall down to an impermeable clay layer. 

Is NJDEP supervising the work?

In 2012, NJDEP fully implemented the Licensed Site Remediation Professional (LSRP) program. LSRPs provide guidance and oversight to ensure projects like this are performed in accordance with state regulations. The LSRP for this site is John Bolan with PS&S.

The work plan for the Site remediation was reviewed and approved by the LSRP and then submitted to NJDEP, which provided no comments.  After each phase of work is completed, PSE&G develops a report documenting its actions. The report is reviewed and approved by the LSRP and submitted to the NJDEP.

Who is responsible for the remediation of the Site?

PSE&G is the responsible party.

If steel sheeting was installed along the river front, why was this current work necessary?

In 2004-2008, a River Front Remediation was conducted between the Site and the Passaic River to address migration of Site constituents in the overburden. The current project addressed the remainder of impacted soils on the interior of the Site.

Are any more buildings targeted for removal?


Dust Management and Air Monitoring

 What do the air monitors do?

Air monitoring stations were installed along all sides of the work area perimeter and between the project area and the closest building when intrusive remediation work was being performed in soil. Air monitoring is now complete and the stations were removed in March 2022.

The stations housed two monitoring devices that operated continuously during active work hours. One device was a photoionization detector (PID), which is a type of vapor detector. It monitored and recorded total volatile organic compounds (TVOCs). The other device was a real-time particulate matter meter that monitored for dust.

The stations were closely monitored to ensure that the project stayed below health-based action levels. A summary of air monitoring results was posted to this website after results were confirmed by an independent laboratory.

Where are the air monitors stationed?

With the completion of site restoration, the air monitors were removed in March 2022.

How quickly did you get air monitoring results?

Perimeter air monitoring equipment provided real-time readings, continually measuring and recording TVOCs and PM-10 (a measurement for particulates or dust) to the project team during work hours.

Additionally, an air sample was collected weekly during remediation activities and sent for analysis at a New Jersey certified laboratory. The current running average for these results was posted on the Air Monitoring page.

The Air Monitoring page on the website provides only data for Benzene and Naphthalene. Were they the only constituents you monitored?

No. In accordance with the Perimeter Air Monitoring Plan, air samples were analyzed for the full suite of volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and metals (the MGP constituents of concern).

If levels for Benzene and Naphthalene were below the PAMP action level, then there was no indication that any of the remaining MGP constituents of concern were at risk of exceeding the residential health-based standards. These MGP constituents of concern were monitored in accordance with the PAMP and can be shared by request.

Drinking Water

Did this site or the remediation work impact local drinking water?

No. Groundwater in the area is not used as a potable water source and the Town of Harrison water supply is not affected.


Were vibration monitors used on buildings across from the project?

Our vibration monitoring plan, created by an outside expert, placed vibration monitors at structures closest to the work to ensure they were protected from damage. The monitors measured ground vibration, which dissipates with distance. So, with assurance the closest structures were protected, buildings further away were also protected. 

Future Use of Site

What is the future use of the PSE&G property?

The PSE&G Site Remediation Group is not aware of any immediate plans to alter the property’s current use.

Will the remedy impact any future development on the property?

No. The remedy will not prevent future development of the Site.

Will the fence line remain the same at the end of the project and who will be responsible for site maintenance?

Yes. The perimeter fence line will remain and be maintained by PSE&G. Temporary fencing around work areas were removed when work in those areas was completed.