Record of Decision National Park Service

Washington Gas East Station Site Anacostia Park

National Capital Parks-East Washington, D.C.

GSA Contract No.: GS-10F-0160J Task Order No.: P3000020416

August 2006

Prepared for:

National Park Service

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able of Contents T Section Page

Declaration................................................................................................ 1 Site Name and Location.................................................................................................1 Statement of Basis and Purpose.....................................................................................1 Assessment of the Site ...................................................................................................1 Description of the Selected Remedy..............................................................................1 Statutory Determination.................................................................................................5 Data Certification Checklist...........................................................................................5 Authorizing Signature....................................................................................................6

Decision Summary ................................................................................... 7 I. Site Name, Location, and Description..................................................................7 II. Site History and Enforcement Activities..............................................................7

Impacts from Gas Manufacturing Activities ........................................................8 Environmental Investigations and Their Results ................................................11 History of Site Response Actions .......................................................................13 Evaluation of the Effectiveness of Ongoing Remedies ......................................17 Cost Recovery.....................................................................................................18

III. Community Participation ...................................................................................18 IV. Scope and Role of the Remedial Action ............................................................18 V. Site Characteristics .............................................................................................19

Site Overview .....................................................................................................19 Remedial Investigation Field Sampling..............................................................20 Conceptual Site Model .......................................................................................20

VI. Current and Future Site and Resource Uses .......................................................24 Current Land Use at the Site...............................................................................24 Current Land Use of Surrounding Properties .....................................................26 Future Land Use at the Site ................................................................................29 Future Land Use at the Surrounding Properties..................................................29 Current and Future Resource Uses .....................................................................29

VII. Summary of Site Risks .......................................................................................30 Human Health Risks...........................................................................................30 Ecological Risk Assessment...............................................................................35

VIII. Remedial Action Objectives...............................................................................37 Risk Management-Based Remediation Goals – Human Health.........................37 Risk Management-Based Remediation Goals – Ecological ...............................38 Other Site Management Objectives ....................................................................38

Table of Contents (cont.) Section Page

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Remediation Goal Verification...........................................................................38 Summary.............................................................................................................39

IX. Description of Alternatives ................................................................................41 Surface Soil.........................................................................................................41 Subsurface Soil ...................................................................................................42 Groundwater .......................................................................................................44 Coal Tar (DNAPL) .............................................................................................46 River Sediment ...................................................................................................46

X. Comparative Analysis of Alternatives................................................................47 Evaluation of Surface Soil Alternatives .............................................................48 Evaluation of the Subsurface Soil Alternative ...................................................53

XI. Principal-Threat Waste.......................................................................................55 Analytes of Exceptional Influence and Waste Identification .............................55

XII. Selected Remedy ................................................................................................56 Summary of the Rationale for the Selected Remedy..........................................56 Description of the Selected Remedy...................................................................57 Summary of the Estimated Remedy Costs .........................................................62 Expected Outcome of the Selected Remedy.......................................................63

XIII. Statutory Determinations....................................................................................63 Protection of Human Health and the Environment ............................................63 Compliance with Applicable or Relevant and Appropriate Requirements ........64 Cost Effectiveness ..............................................................................................64 Use of Permanent Solutions and Alternative Treatment Technologies (or

Resource Recovery Technologies) to the Maximum Extent Practicable ..............................................................................................64

Preference for Treatment as a Principal Element ...............................................64 Five-Year Review Requirements........................................................................65

XIV. Documentation of Significant Changes..............................................................65

References .............................................................................................. 67

A Responsiveness Summary..................................................... A-1

B List and Summary of ARARs for the Selected Remedy ....... B-1

C Cost Calculations.................................................................... C-1

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ist of Tables L Table Page 1 Summary of Human Health Risk Assessment .............................................................30

2 Risk to Human Health from Exposure to Subsurface Soils.........................................33

3 Ranges of Values for Groups of Chemicals in Site Media ..........................................33

4 Range of Concentrations and Average Concentrations of PAHs, Metals, and Total Cyanides in Shallow Soils at the NPS Site.........................................................34

5 Chemicals of Potential Concern for Ecological Risk Assessment...............................36

6 Detailed Evaluation of Remedial Alternatives (East Station RI/FS 1999 and NPS Site 2005).............................................................................................................49

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ist of Figures L Figure Page 1 Site Map, National Park Service Site, Washington, D.C...............................................3

2 Former Extent of Filled Wetlands and Location of Cross Section A-A' (After Hydro-Terra, Inc. March 1999), National Park Service Site, Washington, D.C............9

3 Pits and Boreholes Showing Tar, National Parks Service Site ....................................12

4 Locations of DNAPL Contamination, National Park Service Site, Washington, D.C. ..............................................................................................................................15

5 Cross Section A-A' (After Hydro-Terra, Inc. March 1999), National Park Service, Anacostia Park, Water Street S.E. Site, Washington, D.C. ...........................21

6 Conceptual Site Model (Past, Current, and Potential Exposure Pathways), National Park Service Site, Washington D.C. .......................................................