Update October 2010

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

Operable Unit 1 (40 Willow Avenue)

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 to evaluate NAPL recoverability 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 evaluating long-term NAPL recoverability.    Ongoing and future anticipated activities on the OU-1 site:

 On-going activities:

  • Commence Operation and Maintenance (O&M) measures on the cap and within the holder.  Additional recovery wells will be installed in this phase to optimize tar recoverability from within the containment barrier.
  • 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 maintenance and inspection of the OU-1 concrete cover.
  • 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:

  • Abandoned two groundwater piezometers in the Lynhurst Avenue right-of-way (ROW). 
  • Submitted Interim NAPL Recovery Pilot Test Findings to the NYSDEC and NYSDOH.  The NYSDEC accepted the interim results as well as approved additional NAPL Recovery Pilot Monitoring to further evaluate the long term NAPL recovery at OU-1.
  • Collected groundwater level measurements at OU-1 and vicinity.
  • Submitted a Draft of the Construction Completion Report for OU-1 to the NYSDEC and NYSDOH.

Future near-term activities:

  • Continue pilot tests collections and evaluate NAPL recovery pilot test findings.
  • Continue maintenance and inspection of the OU-1 concrete cover.
  • Continue site restoration activities on the OU-1 property owned by National Grid.
  • Implement the approved work plan to enhance subsurface oxygen levels on a small portion of a private property to assist the natural degradation of concentrations in groundwater.
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:

  • Conducted monitoring well inspections and bail-down testing to determine groundwater flow. There were no field activities in August and September 2010.

Future near-term activities:

  • Install fence around 89 Willow Avenue
  • 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. There were no exceedances of the CAMP levels during the removal of the two piezometers within Lynhurst Avenue during June.  There were no intrusive activities at OU-1 during the month of July 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.  There were no intrusive activities at OU-2 during August and September that required CAMP monitoring.

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.