1. Environmental Investigation by Con Edison Former E115th Street Gas Works November 13, 2007

2. Former MGP Site History Former MGP Site History Investigation Activities and Results Investigation Activities and Results Next Steps Next Steps Presentation Overview

3. Manhattan Center for Science and Math

4. Former E.115 th Street Gas Works (1895 – 1936)

5. Coal Yard/Coal Bins Oil Tanks Generators Purifying Houses Gas Holders Former Gas Works Structures

6. Manufactured Gas Plant (MGP) Substances of Concern Coal tar Coal tar Purifier waste Purifier waste Volatile organics: benzene, toluene, ethylbenzene, xylene (BTEX) Volatile organics: benzene, toluene, ethylbenzene, xylene (BTEX) Semivolatile organics: polycyclic aromatic hydrocarbons (PAHs) Semivolatile organics: polycyclic aromatic hydrocarbons (PAHs)

7. Site Investigation Activities Indoor air quality assessment conducted in July and December 2002 Indoor air quality assessment conducted in July and December 2002 Remedial Investigation performed in August and September 2003 Remedial Investigation performed in August and September 2003 Remedial Investigation Report approved by the NYSDEC in August 2004 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 conducted in August 2004 (on-site) and January 2005 (Harlem River) Supplemental Remedial Investigation Report approved by NYSDEC in September 2005. Supplemental Remedial Investigation Report approved by NYSDEC in September 2005.

8. July 2002 Indoor Air Quality Assessment Purpose: assess potential MGP contamination beneath the school building and its potential impacts on indoor air quality Purpose: assess potential MGP contamination beneath the school building and its potential impacts on indoor air quality Scope included: Scope included: --Indoor air samples from basement and first floor (13) --Indoor air samples from basement and first floor (13) --Soil gas samples from basement and near building (5) --Soil gas samples from basement and near building (5) --Air samples outside of building (4) --Air samples outside of building (4) --Soil samples from basement and near building (4) --Soil samples from basement and near building (4) --One groundwater sample near building --One groundwater sample near building

9. July 2002 Indoor Air Quality Assessment Results All indoor air results were within typical background indoor air range; no indication of MGP impacts All indoor air results were within typical background indoor air range; no indication of MGP impacts Soil gas samples contained elevated VOC levels Soil gas samples contained elevated VOC levels Soil and groundwater results indicated presence of subsurface impacts beneath and near school building Soil and groundwater results indicated presence of subsurface impacts beneath and near school building

10. December 2002 Indoor Air Quality Assessment Purpose: evaluate indoor air quality under winter conditions Purpose: evaluate indoor air quality under winter conditions Scope: 13 indoor air samples from areas sampled in July 2002 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 Results: VOCs indicative of cleaning products, gasoline and paint detected in some samples at levels above background; no discernable MGP impacts observed

11. Remedial Investigation (August 2003- January 2005) Purpose: delineate subsurface MGP impacts within the school property and off-site Purpose: delineate subsurface MGP impacts within the school property and off-site Scope included: Scope included: ---Indoor air quality assessment (August 2004) ---Indoor air quality assessment (August 2004) ---Soil and groundwater sampling inside and around the school building ---Soil and groundwater sampling inside and around the school building ---Sediment sampling in the Harlem River ---Sediment sampling in the Harlem River

12. August 2004 Indoor Air Quality Assessment Results Indoor air quality generally within typical background range; Indoor air quality generally within typical background range; Low levels of VOCs indicative of cleaning products and gasoline present in some samples; 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. VOC levels consistent with previous sampling events; no discernable MGP impacts observed.

13. Remedial Investigation Results Some organic compounds and metals found in surface soil at slightly elevated levels, however, within typical background range; 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 MGP residuals (coal tar) found at depths of 6 feet to 42 feet Elevated levels of MGP constituents detected in groundwater; 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. MGP impacted sediments found in Harlem River at depths 14 feet to 27 feet below sediment surface.

14. Community Outreach Citizen Participation Plan Citizen Participation Plan Fact Sheets and Public Notices at every phase of investigation Fact Sheets and Public Notices at every phase of investigation Update meetings were held with NYCDOE, school administration, UFT and faculty Update meetings were held with NYCDOE, school administration, UFT and faculty Public Meeting for Parents on March 30, 2004 Public Meeting for Parents on March 30, 2004 Internet Content at www.coned.com/publicissues Internet Content at www.coned.com/publicissues www.coned.com/publicissues Toll-Free Hotline 877-602-6633 Toll-Free Hotline 877-602-6633

15. Community Outreach

16. Next Steps Conduct pilot testing of remedial alternatives under consideration. Conduct pilot testing of remedial alternatives under consideration. Finalize Remedial Alternatives Report (draft submitted to NYSDEC, DOE and Mayor’s office in January 2007) 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 Prepare Remedial Action Work Plan for NYSDEC review and approval Implement approved remedy following public review and comment Implement approved remedy following public review and comment