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). National Grid and its consultants and contractors have continued the jet grout barrier wall installation.  The remediation of OU-1 resumed on February 2, 2009.  The fifth column using the modified parameters was installed on February 5, 2009, and we anticipate installing 3 to 5 columns per week.  Two drill rigs will be in operation for the duration of the project, one rig will be injecting grout columns and the other will be drilling in advance of the jet grout rig and supporting quality assurance coring testing. The current plan is to install jet grout columns along the southern wall boundary, nearest to the residential property fenceline, then transition to the eastern or western wall boundaries.  In areas where the fenceline had to be temporarily removed to allow access for the crews, a 20 foot x 10 foot plastic panel/shield has been erected to minimize spillage of clean drilling fluids across the property fenceline and will move as the drilling and injection rigs move.  The daily jet grout work schedule continues to be in effect, 7am to 6pm, Monday through Friday.   However, maintenance activities will be performed on the weekends at the 25 Willow (OU-2) property at the grout plant and in the waste management facility.

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.


• The preliminary results indicate the columns satisfy the requirements for the project and will be used as the basis for future jet grout column installations.

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


• Submit a revised Site Management Plan 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 Remedial Action has been completed on the 89 Willow Avenue (Off site 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 the NYSDEC.


• 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.


• 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. 

Operable Unit 2 (25 Willow Avenue)

OU-2 is the former manufactured gas plant that previously operated at 25 Willow Avenue. 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.

There are two off-site areas that are located adjacent to OU-2 at 89 Willow Avenue and 1 Edgewater Street. 

• 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.  A plan to conduct an additional limited excavation is currently being developed as is a plan for future soil and groundwater management at the property.


• 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 From February 1 through February 25, 2009

CAMP monitoring confirmed that concentrations of vapors and dust associated with intrusive site activities were below levels 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.