nationalgrid May 11 , 2009 Mr. Amen M. Omorogbe, P.E. Project Manager New York State Department of Environmental Conservation MGP Remedial Section, Division of Environmental Remediation Bureau of West em Remedial Action, 11th Floor 625 Broadway Albany, New York 12233-7017 Tracey Bell Manager Environmental Asset Management Re: Bulkhead Alignment Investigation Work Plan Former Citizens Gas Works Manufactured Gas Plant Site Carroll GardenslPublic Place Brooklyn, New York 11231 Site No.: C224012 Dear Mr. Omorogbe: This Bulkhead Alignment Investigation has been submitted for your review and approval. The proposed investigation is required to assess the presence of subsurface obstructions along a possible barrier wall alignment located adjacent to the bulkhead face of the Gowanus Canal at the Carroll Gardens/Public Place Site (Figure 1). The Remedial Design Work Plan (RDWP), dated September 12,2007, included a conceptual remedy consisting of a barrier wall that would mitigate non-aqueous phase liquid (NAPL) migration illto the Gowanus Canal. A barrier wall alignment under evaluation is located along the water-side face of the bulkhead on Parcels II and III (Figure 2). Historical documentation of canal construction suggests that the crib support structure for the bulkhead may extend some distance into the water channel below the canal floor. If so, this would require the wall alignment to be placed some distance fi'om the existing bulkhead into the canal. Permitting as such may not be feasible. Also, the potential of subsurface debris may impede wall installation. The proposed Bulkhead Alignment Investigation consists of a series of steel pipe probes (up to I inch in diameter) along the bulkhead face and offset a few feet into the canal. Sampling of the sediments and fill is not proposed. The probes would be driven into the canal floor sediments approximately 10 to IS feet, or to refusal by resistance or on obstructions. A series of probes would be advanced at roughly 50 to I OO-foot iritervals along the bulkhead face. The steel pipe probes will be driven by hand and/or mechanical means from the top of the bulkhead, a secure platform (e .g. aerial lift), and/or from a stabilized watercraft. The probes may be fitted with a point or sharpened to aid in advancement. The work will be completed within a one week time frame. 287 Maspeth Road, Brooklyn, NY 11211 T: 718.963.5645 D F: 718.963.5611 a [email protected] • www.nationalgrid.com
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nationalgrid
May 11 , 2009
Mr. Amen M. Omorogbe, P.E. Project Manager New York State Department of Environmental Conservation MGP Remedial Section, Division of Environmental Remediation Bureau of West em Remedial Action, 11th Floor 625 Broadway Albany, New York 12233-7017
Tracey Bell
Manager
Environmental Asset Management
Re: Bulkhead Alignment Investigation Work Plan Former Citizens Gas Works Manufactured Gas Plant Site Carroll GardenslPublic Place Brooklyn, New York 11231 Site No.: C224012
Dear Mr. Omorogbe:
This Bulkhead Alignment Investigation has been submitted for your review and approval. The proposed investigation is required to assess the presence of subsurface obstructions along a possible barrier wall alignment located adjacent to the bulkhead face of the Gowanus Canal at the Carroll Gardens/Public Place Site (Figure 1).
The Remedial Design Work Plan (RDWP), dated September 12,2007, included a conceptual remedy consisting of a barrier wall that would mitigate non-aqueous phase liquid (NAPL) migration illto the Gowanus Canal. A barrier wall alignment under evaluation is located along the water-side face of the bulkhead on Parcels II and III (Figure 2). Historical documentation of canal construction suggests that the crib support structure for the bulkhead may extend some distance into the water channel below the canal floor. If so, this would require the wall alignment to be placed some distance fi'om the existing bulkhead into the canal. Permitting as such may not be feasible. Also, the potential of subsurface debris may impede wall installation.
The proposed Bulkhead Alignment Investigation consists of a series of steel pipe probes (up to I inch in diameter) along the bulkhead face and offset a few feet into the canal. Sampling of the sediments and fill is not proposed. The probes would be driven into the canal floor sediments approximately 10 to IS feet, or to refusal by resistance or on obstructions. A series of probes would be advanced at roughly 50 to I OO-foot iritervals along the bulkhead face. The steel pipe probes will be driven by hand and/or mechanical means from the top of the bulkhead, a secure platform (e.g. aerial lift), and/or from a stabilized watercraft. The probes may be fitted with a point or sharpened to aid in advancement. The work will be completed within a one week time frame.
287 Maspeth Road, Brooklyn, NY 11211
T: 718.963.5645 D F: 718.963.5611 a [email protected] • www.nationalgrid.com
Bulkhead Alignment Investigation Carroll Gardens/Public Place Former Citizens Gas Works Manufactured Gas Plant Site Site No.: C224012 May 11, 2009 Page 2
Additional design investigations that may be completed in conjunction with the Bulkhead Alignment Investigation include a video survey of the bulkhead face, a detailed assessment and survey of the outfalls along the bulkhead, and confirmation of the 72 inch sewer pipe invert and rim elevations. One Call and utility companies will be contacted to identify potential utility conflicts within the work area. Probes will not be advanced within 30 feet of the steel and concrete gas tunnel that crosses the canal on Parcel II.
Probe locations and depth and outfall locations will be referenced to existing points that have been surveyed by a New York State Licensed Land Surveyor.
Based on the findings of the program, more sophisticated efforts may be required to investigate obstructions. Should this be required, they would be addressed under a separate work plan submittal.
The proposed work will be conducted in accordance with the attached Site Health and Safety Plan (HASP). The attached HASP has been modified from the Gownaus Canal HASP, dated October 24, 2005, to include a fall protection plan that addresses potential fall hazards associated with landside work near the bulkhead.
If you have any questions or require additional information, please feel free to contact me at (718) 963-5645 or bye-mail at [email protected].
Enclosure
ec: C. Doroski (NYSDOH)
287 Maspeth Road, Brooklyn, NY 11211
T: 718.963.xxxx • F: 718.963.xxxx • [email protected] II www.nationalgrid .com
SITE LOCATION
0 2000 4000
SCALE, FEET
SITE LOCATION MAP
Figure 1May 2009Project 061140-19-2808
BULKHEAD ALIGNMENT INVESTIGATION WORKPLANCARROLL GARDENS/PUBLIC PLACE
BOROUGH OF BROOKLYN, NEW YORK
NATIONAL GRID\CITIZENS\CITIZENS-Bulkhead LOCATION MAP.CDR
SOURCE: Map created with TOPO! ® ©2001 National Geographic (www.nationalgeographic.com/topo)
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