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Learn about the history, investigation results, and next steps regarding the Manhattan Center for Science and Math site. Discover substances of concern, site activities, and community outreach efforts.
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Environmental Investigation by Con Edison Former E115th Street Gas Works November 13, 2007
Presentation Overview • Former MGP Site History • Investigation Activities and Results • Next Steps
Former Gas Works Structures • Coal Yard/Coal Bins • Oil Tanks • Generators • Purifying Houses • Gas Holders
Manufactured Gas Plant (MGP) Substances of Concern • Coal tar • Purifier waste • Volatile organics: benzene, toluene, ethylbenzene, xylene (BTEX) • Semivolatile organics: polycyclic aromatic hydrocarbons (PAHs)
Site Investigation Activities • Indoor air quality assessment conducted in July and December 2002 • Remedial Investigation performed in August and September 2003 • Remedial Investigation Report approved by the NYSDEC in August 2004 • Supplemental Remedial Investigation conducted in August 2004 (on-site) and January 2005 (Harlem River) • Supplemental Remedial Investigation Report approved by NYSDEC in September 2005.
July 2002 Indoor Air Quality Assessment • Purpose: assess potential MGP contamination beneath the school building and its potential impacts on indoor air quality • Scope included: --Indoor air samples from basement and first floor (13) --Soil gas samples from basement and near building (5) --Air samples outside of building (4) --Soil samples from basement and near building (4) --One groundwater sample near building
July 2002 Indoor Air Quality Assessment Results • All indoor air results were within typical background indoor air range; no indication of MGP impacts • Soil gas samples contained elevated VOC levels • Soil and groundwater results indicated presence of subsurface impacts beneath and near school building
December 2002 Indoor Air Quality Assessment • Purpose: evaluate indoor air quality under winter conditions • Scope: 13 indoor air samples from areas sampled in July 2002 • Results: VOCs indicative of cleaning products, gasoline and paint detected in some samples at levels above background; no discernable MGP impacts observed
Remedial Investigation (August 2003- January 2005) • Purpose: delineate subsurface MGP impacts within the school property and off-site • Scope included: ---Indoor air quality assessment (August 2004) ---Soil and groundwater sampling inside and around the school building ---Sediment sampling in the Harlem River
August 2004 Indoor Air Quality Assessment Results • Indoor air quality generally within typical background range; • Low levels of VOCs indicative of cleaning products and gasoline present in some samples; • VOC levels consistent with previous sampling events; no discernable MGP impacts observed.
Remedial Investigation Results • Some organic compounds and metals found in surface soil at slightly elevated levels, however, within typical background range; • MGP residuals (coal tar) found at depths of 6 feet to 42 feet • Elevated levels of MGP constituents detected in groundwater; • MGP impacted sediments found in Harlem River at depths 14 feet to 27 feet below sediment surface.
Community Outreach • Citizen Participation Plan • Fact Sheets and Public Notices at every phase of investigation • Update meetings were held with NYCDOE, school administration, UFT and faculty • Public Meeting for Parents on March 30, 2004 • Internet Content at www.coned.com/publicissues • Toll-Free Hotline 877-602-6633
Next Steps • Conduct pilot testing of remedial alternatives under consideration. • Finalize Remedial Alternatives Report (draft submitted to NYSDEC, DOE and Mayor’s office in January 2007) • Prepare Remedial Action Work Plan for NYSDEC review and approval • Implement approved remedy following public review and comment