Update April 2010

Jet Grout Barrier Wall Completed!
Focus Shifts to Operable Unit 2

Jet Grout Containment Barrier 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 containment barrier (the barrier) at the sector of the former manufactured gas plant site on which the gas relief holder was located (the OU-1, 40 Willow Avenue parcel).  The barrier was completed in early September 2009. Quality assurance coring and hydrogeologic testing of select areas of the barrier was completed and the four walls that comprise the barrier were certified by the Engineer-of-Record in late September 2009.  By November 2009, the jet grout and waste management contractors demobilized their construction equipment and materials from the site.    

Field activities to monitor and study the potential for removing Dense Non-Aqueous Phase Liquid (DNAPL) from within the barrier were initiated in December 2009.  Pilot wells were placed within the holder foundation to evaluate soils just below the bottom of the foundation and within the deeper soils located below the holder but still within the barrier.  A short-term recoverability test has been completed and National Grid is currently analyzing the NAPL recovery findings.  The following bullet points detail ongoing and future anticipated activities on the OU-1 site.

 On-going activities:

  • Continue recovery testing and measurement of three (3) NAPL recovery wells within the barrier as part of the NYSDEC-approved NAPL recovery pilot test.
  • Continue monthly groundwater sampling within the 53 Lynhurst Avenue buffer zone as required by NYSDEC and New York State Department of Health (NYSDOH).

Recently Completed Activities:

  • Installed three DNAPL recovery wells within the barrier in December 2009.
  • Performed CAMP monitoring during the drilling and waste management activities.
  • Submitted a work plan to abandon groundwater piezometers in the Lynhurst Avenue right-of-way (ROW) that were previously monitored during the installation of the barrier.


Future near-term activities:

  • Continue evaluation of the NAPL recovery pilot test findings.
  • Continue review of Clifton OU-1 Construction Completion Report and submit document to NYSDEC and NYSDOH.
  • Resume site restoration activities on the National Grid OU-1 property.

Operable Unit 2 (25 Willow Avenue)

With the completion of the OU-1 barrier installation, focus has shifted 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 also are two off-site areas with MGP residuals that are located adjacent to OU-2 at 89 Willow Avenue and across Bay Street at 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 the Preliminary Design Investigation (PDI).  The PDI activities are conducted to provide additional design related data.  PDI activities were initiated in December 2009 and consist of utility preclearance, geophysical and land surveys, drilling, test pit excavation, and groundwater sample collection throughout the OU-2 properties.

Ongoing activities:

  •  Land survey of the property and offsite areas.

Recently Completed Activities:

  • Completed fence repair activities.
  • Submitted a site management plan for the management of soils and groundwater at 1 Edgewater Street property.
  • Submitted a supplemental remedial investigation work plan to evaluate conditions in the Front Street ROW to the north of the 1 Edgewater Street property.

Future near-term activities:

  • Conduct soil drilling activities on the offsite areas.
  • Conduct groundwater sampling activities as a part of the PDI field activities.

Community Air Monitoring Plan Summary

Operable Unit 1 (40 Willow Avenue)
A Community Air Monitoring Plan (CAMP) is implemented when intrusive activities are performed at Operable Unit 1.  However, there were no intrusive activities at OU-1 during the month of March that required CAMP monitoring. Copies of previous weekly CAMP reports and other site documents for OU-1 are stored at the two public document repositories for the project. 

Operable Unit 2 (25 Willow Avenue)
A Community Air Monitoring Plan (CAMP) is implemented in support of the PDI activities at the OU-2 properties during intrusive work .  The CAMP consists of portable monitors placed upwind and downwind of the work area.  Concentrations of vapors and dust associated with the pre-design investigation drilling and waste handling were below levels requiring action in the NYSDEC and NYSDOH approved plan.

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.