AECOM Report Environment Appendix D Risk Characterization J:\Concord\105627 - MBTA\PROJ\TO-1 Readville\RAO\Report\Final\MBTA Readville Yard 5 RAO- April 2013 A FINAL April 2013.docx Environment Prepared for: Prepared by: Massachusetts Bay Transportation Authority AECOM Ten Park Plaza 250 Apollo Drive Boston, Massachusetts 02116 Chelmsford, Massachusetts 60133920.1.01 April 2013 Method 3 Risk Characterization Report MBTA Readville Yard Site Industrial Drive, Dedham and Readville, Massachusetts RTN 3-2856 Environment Prepared for: Prepared by: Massachusetts Bay Transportation Authority AECOM Ten Park Plaza 250 Apollo Drive Boston, Massachusetts 02116 Chelmsford, Massachusetts 60133920.1.01 April 2013 Method 3 Risk Characterization Report MBTA Readville Yard Site Industrial Drive, Dedham and Readville, Massachusetts RTN 3-2856 _________________________________ Prepared By Timothy F. Markey, Senior Risk Assessor _________________________________ Reviewed By Elissa J. Brown, CPG, CHMM, LEP, LSP AECOM Report Environment i Contents 1.0  Introduction ...................................................................................................................... 1-1  2.0  Methodology .................................................................................................................... 2-1  3.0  Site Characterization for Risk Assessment ................................................................. 3-1  4.0  Hazard Identification ....................................................................................................... 4-1  4.1  Data Used in Risk Characterization .................................................................................... 4-1  4.1.1  Soil Data ................................................................................................................ 4-1  4.1.2  Groundwater Data ................................................................................................ 4-4  4.1.3  Methods for Summarizing Data ............................................................................ 4-5  4.2  Selection of Compounds of Concern .................................................................................. 4-6  4.2.1  Soil COCs ............................................................................................................. 4-7  4.2.2  Groundwater COCs .............................................................................................. 4-7  4.2.3  Summary of COCs ................................................................................................ 4-7  5.0  Dose-Response Assessment ........................................................................................ 5-1  5.1  Carcinogenic Dose-Response ............................................................................................ 5-1  5.2  Noncarcinogenic Dose-Response....................................................................................... 5-2  6.0  Exposure Assessment ................................................................................................... 6-1  6.1  Potential Receptors and Exposure Scenarios .................................................................... 6-1  6.1.1  Site Characterization for Exposure Assessment ................................................. 6-2  6.1.2  Potential Receptors Evaluated in the Risk Assessment ..................................... 6-3  6.2  Method for Quantifying Exposure Dose .............................................................................. 6-5  6.3  Exposure Points and Exposure Point Concentrations ....................................................... 6-7  6.3.1  Soil ......................................................................................................................... 6-8  6.3.2  Groundwater ....................................................................................................... 6-11  7.0  Human Health Risk Characterization ............................................................................ 7-1  7.1  Non-Cancer Risk .................................................................................................................. 7-2  7.2  Cancer Risk .......................................................................................................................... 7-2  7.3  Number of Significant Figures in the Risk Characterization ............................................... 7-2  7.4  Risk Characterization For a Potential Trespasser at the Site ............................................ 7-3  7.5  Risk Characterization For a Potential Future Construction Worker at the Site ................. 7-3  J:\Con cord\105627 - MBTA\PROJ\TO-1 April 2013 Readville\RAO\Report\Appendices\Appendix D - Risk Characterization\Readville Yard Method 3_Final_4-1- 2013.docx AECOM Report Environment ii 7.6  Risk Characterization For a Potential Commercial/Industrial at the Site ........................... 7-4  7.7  Comparison to Applicable or Suitably Analogous Standards ............................................. 7-4  7.8  Uncertainties in the Health Risk Assessment ..................................................................... 7-5  7.8.1  Hazard Identification ............................................................................................. 7-5  7.8.2  Dose-Response Assessment ............................................................................... 7-5  7.8.3  Human Health Exposure Assessment ................................................................. 7-8  7.8.4  Risk Characterization ............................................................................................ 7-9  7.8.5  Special Considerations for Lead ........................................................................ 7-10  7.8.6  Summary of Sources of Uncertainty .................................................................. 7-11  8.0  Evaluation of Potential Risks to Safety and Public Welfare ...................................... 8-1  8.1  Evaluation of Potential Risks to Safety ............................................................................... 8-1  8.2  Public Welfare Risk Characterization .................................................................................. 8-2  8.2.1  Characterization of Risks to Public Welfare ......................................................... 8-2  8.2.2  Upper Concentration Limits .................................................................................. 8-3  8.2.3  Public Welfare Risk Characterization Conclusions ............................................. 8-3  9.0  Environmental Risk Characterization ........................................................................... 9-1  9.1  Stage I Environmental Screening ........................................................................................ 9-1  9.1.1  Identification of Complete Exposure Pathways ................................................... 9-2  10.0 Summary and Conclusions of Risk Characterization – Human Health, Safety, Public Welfare and Environment ................................................................................. 10-1  11.0 References ..................................................................................................................... 11-1  J:\Con cord\105627 - MBTA\PROJ\TO-1 April 2013 Readville\RAO\Report\Appendices\Appendix D - Risk Characterization\Readville Yard Method 3_Final_4-1- 2013.docx AECOM Report Environment iii List of Attachments Attachment A - Soil and Groundwater Data and Exposure Point Concentration Calculations Attachment B - Risk Characterization Tables – MassDEP Trespasser ShortForms Attachment C - Risk Characterization Tables – MassDEP Construction Worker ShortForms Attachment D - Risk Characterization Tables – AECOM Spreadsheets for Commercial/Industrial Worker List of Tables Table 1 Summary of Soil Exposure Point Concentrations Table 2 Summary of Noncarcinogenic and Carcinogenic Risk Due to Potential Soil Exposure Table 3 Comparison of Exposure Point Concentrations to MCP Method 3 Upper Concentration Limits J:\Con cord\105627 - MBTA\PROJ\TO-1 April 2013 Readville\RAO\Report\Appendices\Appendix D - Risk Characterization\Readville Yard Method 3_Final_4-1- 2013.docx 1-1 AECOM Report Environment 1.0 Introduction This Massachusetts Contingency Plan (310 CMR 40.0000 – the MCP) Method 3 Risk Characterization was performed to determine whether potential exposure to environmental media located at the disposal site on the Massachusetts Bay Transportation Authority (MBTA) Readville Yard facility (“the Site”) located on Industrial Drive at the border between Dedham and Boston, Massachusetts, associated with Release Tracking Number (RTN) 3-2856 may pose a potential for significant risk of harm to human health, safety, public welfare, and the environment as defined by the Massachusetts Contingency Plan (MCP, 310 CMR 40.0000). Potential risks are evaluated under current land use and reasonably foreseeable future land use conditions in the absence of further remediation. The MCP defines a disposal site as including all locations where oil and/or hazardous materials (OHM) have come to be located (the Site or the Disposal Site). The Disposal Site associated with RTN 3-2856 includes an approximately 42-acre area located on Industrial Drive and straddles the boundary between the Town of Dedham and the City of Boston (Readville), Massachusetts. Approximately 21 acres of the Site are located in Readville and 21 acres are located in the Town of Dedham. The portion of the Site located in Dedham is zoned general residential and the portion of the Site located in Readville is zoned general and light manufacturing. The Disposal Site does not include Industrial Drive, which is also owned by the MBTA. The Site location is shown in Figure 1 and the Site Plan is depicted in Figure 2 of the Class A-3 RAO report. A Supplemental Phase II Method 3 baseline risk assessment for the Site was prepared by AECOM (AECOM, 2010), on behalf of the MBTA. Based on the results of the baseline risk assessment, it was concluded that the Site should be remediated to eliminate the potential risk that could result from direct contact with soils and fill containing arsenic, lead, antimony, barium, chromium, cobalt, copper, nickel, zinc, extractable petroleum hydrocarbon (EPH) parameters, and select polycyclic aromatic hydrocarbons (PAHs). The risk assessment summarized in this Response Action Outcome (RAO) Statement report, to which this Risk Characterization is an Appendix, was performed using a Method 3 approach (Site-specific risk assessment), as allowed by the MCP. It provides an update to and supersedes the 2010 Method 3 risk assessment and evaluates post-remedial Site conditions. The results of this Method 3 risk assessment were used to confirm that further remediation is not required and to support the development of a RAO statement for the Site. The results of this risk assessment are intended to support the Class A-3 RAO for the site (RTN 4- 20842). As stated in 310 CMR 40.1036(3), a Class A-3 RAO indicates that: (a) a Permanent Solution has been achieved; (b) the level of oil and hazardous material in the environment has not been reduced to background; (c) one or more Activity and Use Limitations have been implemented pursuant to 310 CMR 40.1012 to maintain a level of No Significant Risk; and (d) OHM at the disposal site do not exceed an applicable Upper Concentration Limit in Soil or Groundwater listed at 310 CMR 40.0996(7). J:\Concord\105627 - MBTA\PROJ\TO-1 R eadville\RAO\Report\Appendices\Appendix D - Risk April 2013 Characterization\Readville Yard Method 3_Final_4-1- 2013.docx 1-2 AECOM Report Environment This Method 3 Risk Characterization assumes that an AUL will be implemented to prohibit future residential use of the Site or use of the Site as a park/playground and/or daycare. Additionally, it assumes that the AUL will preclude excavation of soil without meeting certain precautions. J:\Concord\105627 - MBTA\PROJ\TO-1 R eadville\RAO\Report\Appendices\Appendix D - Risk April 2013 Characterization\Readville Yard Method 3_Final_4-1- 2013.docx 2-1 AECOM Report Environment 2.0 Methodology This risk assessment was completed in accordance with procedures and standards for the characterization of the risk of harm to health, safety, public welfare and the environment as presented in Subpart I, 310 CMR 40.0900 of the MCP, and is intended to meet the Response Action Performance Standard (RAPS) specified in 310 CMR 40.0191. The risk assessment was performed using a Method 3 approach (Site-specific risk assessment), as described in the MCP. A Method 3 Risk Characterization includes assessment of potential risk of harm to human health, safety, public welfare, and ecological receptors under all current and reasonably foreseeable Site activities and uses. The purpose of this risk characterization is to provide a Method 3 evaluation of soil and groundwater conditions at the Site. The results of this risk characterization were utilized to establish whether a level of "No Significant Risk," as that term is defined in the MCP, exists at the Site. The risk assessment was prepared in accordance with current Massachusetts Department of Environmental Protection (MassDEP) guidance, including, but not limited to:  The MCP. 310 CMR 40.0000. Last Revised 2008.  MassDEP, 1995. Guidance for Disposal Site Risk Characterization In Support of the Massachusetts Contingency Plan.  MassDEP, 1996. Guidance for Disposal Site Risk Characterization In Support of the Massachusetts Contingency Plan. *** Chapter 9 *** Method 3 Environmental Risk Characterization.  MassDEP. 2002a, 2002b, 2002c, 2007a, 2009. Technical Updates. Office of Research and Standards.  MassDEP. 2002d. Characterizing Risks Posed by Petroleum Contaminated Sites.  MassDEP. 2008b. ShortForms. Method 3 Human Health Risk Assessment. The Method 3 Risk Characterization consists of the following steps:  Site Characterization, Section 3.0;  Hazard Identification, Section 4.0;  Human Health Dose-Response Assessment, Section 5.0;  Human Health Exposure Assessment, Section 6.0;  Human Health Risk Characterization, Section 7.0;  Evaluation of Risk of Harm to Safety and Public Welfare, Section 8.0; and  Stage I Environmental Risk Characterization, Section 9.0. The risk characterization also includes a discussion of uncertainties, referred to as the Uncertainty Analysis (Section 10.0). J:\Concord\105627 - MBTA\PROJ\TO-1 R eadville\RAO\Report\Appendices\Appendix D - Risk April 2013 Characterization\Readville Yard Method 3_Final_4-1- 2013.docx 3-1 AECOM Report Environment 3.0 Site Characterization for Risk Assessment The MBTA Readville Yard property occupies an approximately 42-acre area located on Industrial Drive and straddles the boundary between the Town of Dedham and the City of Boston (Readville), Massachusetts. The Site is roughly an elongated teardrop shape and its perimeter is defined by a loop railroad track. The Site is enclosed by an 8-foot tall chain link fence, which restricts access to the Site. The MBTA property extends beyond the railroad track fencing and includes Industrial Drive. The Site is mostly unpaved, with the exception of Industrial Drive and a driveway approximately 100 feet wide and 1,700 feet long running east-west along the northern side of the Site. The Site is abutted by residential properties to the north, east, and west, and by industrial properties to the south. Residential and commercial properties abut the Site to the west on Ashcroft Street and to the north opposite the former Dedham Secondary rail line (a.k.a. the “Orphan Line”) on Milton/W. Milton Street. Commercial and industrial properties, including a school bus garage and storage yard and a gravel crushing operation, are located to the south, opposite Industrial Drive. The MBTA Readville commuter rail station, including commuter parking lots and the MBTA 2-Yard facility, is located to the east. Materials used for railroad maintenance (ties, track panels, etc.) are currently stored in various areas on the Site. The western portion of the Property was fenced off and posted with warning signs in October 2001 to restrict access to stockpiles containing soil and miscellaneous debris located within this area. Historical site building remnants and a drainage ditch located along the approximate Site centerline are present. It is likely these uses will continue in the foreseeable future, and activities similar to those currently conducted at the Property can be reasonably expected to continue. Excavation of soil at the Site is not planned, but could occur in the future for the purpose of utility repair, or other construction. The potential for conversion of the Site to residential purposes, or for use as a park/playground, were not considered by this Method 3 Risk Characterization due to the implementation of an AUL precluding these uses. For the purposes of the risk characterization and previous investigation/evaluations, the 42-acre Site was divided into four separate potential exposure areas (Areas 1 through 4) based primarily on historical use, types and concentrations of contaminants, and existing zoning and access. The four areas assessed in this Method 3 risk characterization include:  Area 1 – Orphan Line: The Orphan Line was formerly the Dedham Secondary Line and consists of an approximately 90-foot wide by 3,200–foot long section of abandoned railroad tracks along the Site’s northern boundary.  Area 2 – Western Fence Line (adjacent to Ashcroft Street): Area 2 is a narrow strip of land located along the southwestern Site boundary between the exclusion zone (EZ) and a wooded area followed by residential properties on Ashcroft Street.  Area 3 - Main Rail Yard: The Main Rail Yard is the largest area evaluated for this Site. Comprising approximately 21 acres, the area contains both active and inactive tracks. The Main Rail Yard is currently used by MBTA and Massachusetts commuter rail operators for storage of railroad materials (ties, track panels, etc.), and has a long history of use as a former railroad J:\Concord\105627 - MBTA\PROJ\TO-1 R eadville\RAO\Report\Appendices\Appendix D - Risk April 2013 Characterization\Readville Yard Method 3_Final_4-1- 2013.docx