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

Environmental Environmental Investigation by Con Investigation by Con

EdisonEdison

Former E115th Street Former E115th Street Gas WorksGas Works

November 13, 2007November 13, 2007

Former MGP Site HistoryFormer MGP Site History

Investigation Activities and ResultsInvestigation Activities and Results

Next StepsNext Steps

Presentation OverviewPresentation Overview

Manhattan Center for Science and MathManhattan Center for Science and Math

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

• Coal Yard/Coal Bins

• Oil Tanks

• Generators

• Purifying Houses

• Gas Holders

Former Gas Works StructuresFormer Gas Works Structures

Manufactured Gas Plant Manufactured Gas Plant (MGP) Substances of (MGP) Substances of

ConcernConcern Coal tarCoal tar

Purifier waste Purifier waste

Volatile organics: Volatile organics: benzene, toluene, benzene, toluene, ethylbenzene, xylene ethylbenzene, xylene (BTEX)(BTEX)

Semivolatile organics: Semivolatile organics: polycyclic aromatic polycyclic aromatic hydrocarbons (PAHs)hydrocarbons (PAHs)

Site Investigation ActivitiesSite Investigation Activities Indoor air quality assessment conducted in July and Indoor air quality assessment conducted in July and

December 2002December 2002

Remedial Investigation performed in August and Remedial Investigation performed in August and September 2003September 2003

Remedial Investigation Report approved by the Remedial Investigation Report approved by the NYSDEC in August 2004NYSDEC in August 2004

Supplemental Remedial Investigation conducted in Supplemental Remedial Investigation conducted in August 2004 (on-site) and January 2005 (Harlem August 2004 (on-site) and January 2005 (Harlem River)River)

Supplemental Remedial Investigation Report Supplemental Remedial Investigation Report approved by NYSDEC in September 2005. approved by NYSDEC in September 2005.

July 2002 Indoor Air Quality July 2002 Indoor Air Quality AssessmentAssessment

Purpose: assess potential MGP Purpose: assess potential MGP contamination beneath the school building contamination beneath the school building and its potential impacts on indoor air qualityand its potential impacts on indoor air quality

Scope included:Scope included: --Indoor air samples from basement and first --Indoor air samples from basement and first

floor (13)floor (13) --Soil gas samples from basement and near --Soil gas samples from basement and near

building (5)building (5) --Air samples outside of building (4)--Air samples outside of building (4) --Soil samples from basement and near --Soil samples from basement and near

building (4)building (4) --One groundwater sample near building--One groundwater sample near building

July 2002 Indoor Air Quality July 2002 Indoor Air Quality Assessment ResultsAssessment Results

All indoor air results were within typical All indoor air results were within typical background indoor air range; no background indoor air range; no indication of MGP impacts indication of MGP impacts

Soil gas Soil gas samplessamples contained elevated contained elevated VOC levels VOC levels

Soil and groundwater results indicated Soil and groundwater results indicated presence of subsurface impacts presence of subsurface impacts beneath and near school buildingbeneath and near school building

December 2002 Indoor Air December 2002 Indoor Air Quality AssessmentQuality Assessment

Purpose: evaluate indoor air quality under Purpose: evaluate indoor air quality under winter conditionswinter conditions

Scope: 13 indoor air samples from areas Scope: 13 indoor air samples from areas sampled in July 2002 sampled in July 2002

Results: VOCs indicative of cleaning Results: VOCs indicative of cleaning products, gasoline and paint detected in products, gasoline and paint detected in some samples at levels above background; some samples at levels above background; no discernable MGP impacts observed no discernable MGP impacts observed

Remedial Investigation Remedial Investigation (August 2003- January 2005)(August 2003- January 2005)

Purpose: delineate subsurface MGP impacts Purpose: delineate subsurface MGP impacts within the school property and off-sitewithin the school property and off-site

Scope included:Scope included:

---Indoor air quality assessment (August ---Indoor air quality assessment (August 2004)2004)

---Soil and groundwater sampling inside and ---Soil and groundwater sampling inside and around the school buildingaround the school building

---Sediment sampling in the Harlem River---Sediment sampling in the Harlem River

August 2004 Indoor Air August 2004 Indoor Air Quality Assessment Results Quality Assessment Results Indoor air quality generally within typical Indoor air quality generally within typical

background range;background range; Low levels of VOCs indicative of cleaning Low levels of VOCs indicative of cleaning

products and gasoline present in some products and gasoline present in some samples;samples;

VOC levels consistent with previous VOC levels consistent with previous sampling events; no discernable MGP sampling events; no discernable MGP impacts observed.impacts observed.

Remedial Investigation Remedial Investigation ResultsResults

Some organic compounds and metals found in Some organic compounds and metals found in surface soil at slightly elevated levels, however, surface soil at slightly elevated levels, however, within typical background range; within typical background range;

MGP residuals (coal tar) found at depths of 6 MGP residuals (coal tar) found at depths of 6 feet to 42 feetfeet to 42 feet

Elevated levels of MGP constituents detected in Elevated levels of MGP constituents detected in groundwater; groundwater;

MGP impacted sediments found in Harlem River MGP impacted sediments found in Harlem River at depths 14 feet to 27 feet below sediment at depths 14 feet to 27 feet below sediment surface.surface.

Community OutreachCommunity Outreach Citizen Participation PlanCitizen Participation Plan Fact Sheets and Public Notices at every Fact Sheets and Public Notices at every

phase of investigationphase of investigation Update meetings were held with NYCDOE, Update meetings were held with NYCDOE,

school administration, UFT and facultyschool administration, UFT and faculty Public Meeting for Parents on March 30, 2004 Public Meeting for Parents on March 30, 2004 Internet Content at Internet Content at

www.coned.com/publicissueswww.coned.com/publicissues Toll-Free Hotline 877-602-6633Toll-Free Hotline 877-602-6633

Community OutreachCommunity Outreach

Next StepsNext Steps

Conduct pilot testing of remedial alternatives Conduct pilot testing of remedial alternatives under consideration. under consideration.

Finalize Remedial Alternatives Report (draft Finalize Remedial Alternatives Report (draft submitted to NYSDEC, DOE and Mayor’s submitted to NYSDEC, DOE and Mayor’s office in January 2007)office in January 2007)

Prepare Remedial Action Work Plan for Prepare Remedial Action Work Plan for NYSDEC review and approvalNYSDEC review and approval

Implement approved remedy following public Implement approved remedy following public review and commentreview and comment