Update January 2010

Jet Grout Barrier Wall Completed!

Focus Shifts to Operable Unit 2
Operable Unit 1 (40 Willow Avenue)
National Grid and NYSDEC Reached a Major Milestone on the Final Major Phase of Remediation of OU-1 (40 Willow Ave. Sector) of Former Manufactured Gas Plant (MGP) Site

The New York State Department of Environmental Conservation (NYSDEC) and National Grid (formerly KeySpan) have completed the installation of the jet grout barrier wall at the sector of the former manufactured gas plant site on which the gas holder and supporting facilities were located (the OU-1, 40 Willow Avenue parcel).  Quality assurance coring and hydrogeologic testing of select areas of the barrier wall have been completed, and the four walls have been certified by the Engineer-of-Record.  All site restoration activities have been completed and the jet grout and waste management contractors have demobilized from the site.
Field activities to monitor and study the potential for removing Dense Non-Aqueous Phase Liquid (DNAPL) from within the containment barrier were initiated in December 2009.  Pilot wells were placed within the holder foundation, adjacent to the former holder to evaluate soils just below the bottom of the holder foundation, and within coarse grained soils located at significant depths outside of the holder.  The next step is to perform a short-term recoverability test and analyze the results.  The following bullet points detail ongoing and future anticipated activities on the OU-1 site.

 Ongoing activities:

  • Began well development of three NAPL recovery wells within the jet grout barrier wall in support of the NYSDEC approved NAPL recovery pilot test.
  • Continued monthly groundwater sampling within the Lynhurst Avenue #53 buffer zone as agreed to with the Lynhurst residents in the June 2009 public meeting and as required by NYSDEC/DOH.

Future (two week look-ahead) activities:

  • Complete development of NAPL recovery pilot test wells at the concrete work platform within the jet grout barrier wall.
  • Finalize the Clifton OU-1 Construction Completion Report and submit to NYSDEC/DOH.

Recently Completed Activities:

  • Installed three DNAPL recovery wells within the jet grout barrier containment walls.
  • Performed CAMP monitoring during the drilling and waste management activities.

Operable Unit 2 (25 Willow Avenue)

With the completion of the OU-1 barrier wall installation, focus now shifts to the remedial design investigation and remedial construction of OU-2.    OU-2 is the site of the former manufactured gas plant that previously operated at 25 Willow Avenue and was closed in 1957.  There are two off-site areas that are located adjacent to OU-2 at 89 Willow Avenue and 1 Edgewater Street.  The remedial activities at OU-2 have progressed with the approval of the final remedial design work plan by NYSDEC and NYSDOH, including activities to be conducted during Preliminary Design Investigation (PDI).  PDI activities were initiated in December and consist of utility preclearance and geophysical surveys throughout the OU-2 properties.
Ongoing activities:

  • Initiated PDI activities including utility preclearance and geophysical surveys of the OU-2 properties.

Future (two week look-ahead) activities:

  • Complete the utility preclearance and the geophysical survey for the OU-2 properties.
  • Initiate pre-characterization activities including geoprobe drilling and sampling.

Completed Activities:

  • A remedial action has been completed on the 89 Willow Avenue parcel adjacent to the 25 Willow Avenue National Grid parking lot. Impacted shallow soils have been removed and the site has been backfilled and graded at the request of the property owner.  Field work was performed under the observation of NYSDEC. 
  • The plan to investigate an additional parcel acquired by the owner of 89 Willow and perform the additional limited excavation has been approved by NYSDEC and NYSDOH.  Investigative borings have been installed at the 89 Willow Avenue property and samples analyzed to further evaluate soil conditions.  The results were provided to the NYSDEC.  
  • The final remedial investigation report for 1 Edgewater Street has been approved by NYSDEC and NYSDOH and a draft plan for soil and groundwater management was developed and submitted to the NYSDEC/ NYSDOH.
  • Initiated utility preclearance and the geophysical survey for the OU-2 properties.

Community Air Monitoring Plan Summary
A Community Air Monitoring Plan (CAMP) was implemented in support of the NAPL recovery well installations at 40 Willow Avenue Operable Unit 1 (OU-1) of the Clifton Former MGP Site in December.  The CAMP consisted of portable monitors placed upwind and downwind of the work area.

CAMP monitoring summary from December 16, 2009 through December 21, 2009 (end of instrusive activities):

CAMP monitoring confirmed that concentrations of vapors and dust associated with intrusive site activities were below levels requiring action in the NYSDEC and NYSDOH- approved plan.  Copies of weekly CAMP and SVMP reports and other site documents for OU-1 have been provided to the two public document repositories for the project.  The repositories are located at:  


Community Board 1
One Edgewater Plaza
Room 311
Staten Island, NY 10305
Phone #: (718) 981-6900
Borough President’s Office
Borough Hall
Staten Island, New York 10301
Phone #: (718) 816-2057

If you have any questions or comments about the work on the site, please use the site's Telephone Hotline at 718-982-7349.