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). National Grid and its consultants and contractors have continued the jet grout barrier wall installation. The remediation of OU-1 will resume the week of February 2, 2009. During the break, workers have been on site performing equipment maintenance, calibration checks and reestablishing site controls. The jet grout contractor has provided a revised approach based on the success of the last four column installations and we have negotiated an agreement to use this approach going forward.
Site personnel will resume 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 worker health and safety 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:- Mobilizing personnel and equipment to the site to commence jet grouting and waste management activities.
- Installing protective sandbag and plastic barrier wall within the 20 foot buffer zone to prevent and/or manage release of grout material.
Future (two week look-ahead) activities:
- Drill and install casings along the eastern and southern walls in preparation for jet grouting and QA core testing.
- Restart jet grouting along the eastern wall using the modified parameters
- Install protective barrier wall at select offsite locations in preparation for jet grouting along the western wall.
Completed Activities:
Many Remedial Actions for the Clifton former Manufactured Gas Plant site have been completed since the Remedial Action Plan for Operable Unit 1 (40 Willow Avenue) was selected by the NYSDEC. Among the more significant completed actions are:
- 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.
- 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.
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.
From December 18, 2008 through January 30, 2009
There were no intrusive activities during this time and active, full-scale monitoring was not completed. Limited CAMP and SVMP measurements were collected during this period. CAMP and SVMP measurements will commence next week for the start of intrusive activities.
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 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.