Update March 10, 2009

Operable Unit 1 (40 Willow Avenue)
National Grid, NYSDEC Begin 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 begun a major phase of remedial work 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).  The remediation of OU-1 resumed on February 2, 2009.  National Grid and its consultants and contractors have continued the jet grout barrier wall installation. Because of the additional time needed to find the optimum injection parameters, the jet grout barrier schedule has shifted to a new completion date of October 2009.  National Grid is currently working with the consultants and contractors to minimize the schedule impacts to the community and expedite remediation of the site.

Site personnel are collecting measurements from wells and sampling points around the work zone as part of the Soil Vapor Monitoring Plan (SVMP) and air quality measurements as part of the Health and Safety Plan (HASP) and Community Air Monitoring Plan (CAMP) program to ensure worker and community safety.  From the start of field work to present, concentrations of vapors and dust associated with intrusive site activities have been measured below levels in the New York State Department of Conservation and New York State Department of Health approved plans.

Ongoing activities:

  • Injecting jet grout columns on the southern wall boundary of the barrier in accordance with the contractor specifications and Site Management Plan.

  • Managing jet grout wastes in the waste management facility and stabilizing the wastes for off site treatment and disposal in accordance with the approved work plans and state and federal regulations. 

  • Continuing CAMP, SVMP and real time air monitoring to protect workers and the community. 

  • Continuing quality assurance coring and testing to determine the effectiveness of the installed jet grout columns.  Preliminary quality assurance coring testing and hydrologic testing to date confirms the columns have achieved project requirements..

Future (two week look-ahead) activities:

  • Continue jet grout column installations on the southern wall boundary of the barrier wall. 

  • Continue waste management facility operations and off site transportation and disposal of generated wastes.

  • Receive additional equipment, cement and slag storage vessels,  to improve efficiency of jet grout operations.  The equipment will be placed and used on the 25 Willow Avenue (OU-2) property.

  • Completing the revision to the Site Management Plan to be delivered to the two document repositories listed below.  The revised plan includes the modified approach to installing the jet grout columns at the site.   

Completed Activities:

  • A trench drain has been installed along the property line at the backyards of the Lynhurst Avenue properties to mitigate flow of surface water from the cap area to the Lynhurst Avenue properties;

  • Community Air Monitoring Plan (CAMP) units are in place on the 40 Willow Avenue parcel and within the buffer zone on the Lynhurst residential properties to monitor for potential vapor and dust releases, if any, that might occur during construction activities at the site and to assist in determining when additional mitigation measures need to be taken. The CAMP units and Z-nose portable unit are calibrated to provide notice well before the New York State Department of Environmental Conservation and Department of Health response levels are reached so mitigation can take place proactively -- long before CAMP action levels are reached.

  • Soil vapor probes and groundwater piezometers have been installed within the buffer zone on the Lynhurst residential properties and around the former gas holder footprint to assess soil vapor and groundwater quality conditions for the on-going jet grout barrier installation.

  • The vibration wire piezometers (VWP) have been installed within the sheetpile barrier and are operational. The 3 VWPs will be used to measure temperature and pressure variations during the jet grouting and provide useful data for optimizing the jet grout injection.

  • The waste management facility retrofitting is complete and is operational 

  • The reinforced concrete working surface has been installed at 40 Willow Avenue.  Jet grout collars have been cored into the concrete working surface to allow for an air tight seal between the drilling operations and the return lines to the waste management facility.

  • Four jet grout columns using modified parameters were installed and quality assurance coring and testing was performed.

  • A large capacity pump to support the drilling operations is setup on 25 Willow Avenue and offers increased productivity. 

Operable Unit 2 (25 Willow Avenue)

OU-2 is the former manufactured gas plant that previously operated at 25 Willow Avenue.  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 recent submittal to and approval of the final remedial design work plan by NYSDEC and NYSDOH.  The preliminary remedial design activities have been placed on hold to allow for completion of the OU-1 remedy which uses the 25 Willow Avenue property as a staging area.  Remedial design activities at OU-2 will commence once the OU-1 remedy has been completed.

  • 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 the additional parcel and perform the additional limited excavation has been submitted to the NYSDEC and NYSDOH for review and comment.  A plan for future soil and groundwater management at the property is currently being developed and will incorporate the results from the above mentioned investigation and limited excavation work.

  • The final remedial investigation report for 1 Edgewater Street has recently been submitted to and approved by NYSDEC and NYSDOH and a plan is being developed for soil and groundwater management at the property. 

Community Air Monitoring Plan Summary

A Community Air Monitoring Plan (CAMP) and Soil Vapor Monitoring Plan (SVMP) has been implemented in support of remedial activities at 40 Willow Avenue Operable Unit 1 (OU-1) of the Clifton Former MGP Site.   The CAMP consists of an automated network of fixed air monitoring stations that is supplemented with measurements collected daily during intrusive work activities.

CAMP monitoring summary from February 26 through March 6, 2009

CAMP monitoring confirmed that concentrations of vapors and dust associated with intrusive site activities were below levels requiring action in the New York State Department of Conservation and New York State Department of Health approved plan. Copies of weekly CAMP and SVMP reports and other site documents are being 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.