SDMS DOCID# 1123240 First Five-Year Review Report for Pemaco Superfund Site Maywood, California September 2010 u.S. Environmental Protection Agency, Region 9 San Francisco, California Approved by: Date: ~M~~~ Kathleen Salyer Assistant Director Superfund Division California Site Cleanup Branch Table of Contents Executive Summary..............................................................................................................ES-1 Five-Year Review Summary Form .......................................................................................ES-2 1.0 Introduction .....................................................................................................................4 2.0 Site Chronology ..............................................................................................................5 3.0 Background .....................................................................................................................7 3.1 Site Location and Physical Characteristics ...................................................................7 3.2 Former, Current, and Future Land Use.........................................................................8 3.3 History of Contamination...............................................................................................9 3.4 Initial Response.............................................................................................................9 3.5 Basis for Taking Action................................................................................................10 4.0 Remedial Actions ..........................................................................................................11 4.1 Remedy Selection .......................................................................................................11 4.1.1 Surface and Near-Surface Soil Remediation ..........................................................12 4.1.2 Upper Vadose-Zone Soil and Perched Groundwater (3 –35 ft bgs)........................12 4.1.3 Lower Vadose Zone Soil and Exposition Zone Groundwater..................................12 4.2 Remediation Levels.....................................................................................................13 4.3 Remedy Implementation .............................................................................................16 4.3.1 Soil Capping ............................................................................................................16 4.3.2 Groundwater- and Vapor-Extraction System...........................................................16 4.3.3 Electrical Resistance Heating System.....................................................................19 4.3.4 Groundwater and Vapor Treatment Plant ...............................................................19 4.3.5 Institutional Controls................................................................................................20 4.4 Required Monitoring....................................................................................................20 4.5 System Operations/Operation and Maintenance (O&M).............................................21 5.0 Progress Since the Last Five-Year Review.................................................................25 i Table of Contents, Continued 6.0 Five Year Review Process............................................................................................26 6.1 Administrative Components, Community Notification, Document Review ..................26 6.2 Community Notification and Involvement....................................................................26 6.3 Document Review .......................................................................................................26 6.4 Data Review................................................................................................................27 6.4.1 Soil ..........................................................................................................................27 6.4.2 Groundwater............................................................................................................28 6.5 Site Inspection.............................................................................................................48 6.6 Interviews ....................................................................................................................49 6.6.1 Technical Interviews................................................................................................49 6.6.2 Community Interviews .............................................................................................50 7.0 Technical Assessment .................................................................................................51 7.1 Question A: Is the remedy functioning as intended by the decision documents? .......51 7.1.1 Remedial Action Performance.................................................................................51 7.1.2 System Operations / O&M.......................................................................................52 7.1.3 Opportunities for Optimization.................................................................................52 7.1.4 Early indicators of potential issues ..........................................................................53 7.1.5 Implementation of Institutional Controls ..................................................................53 7.2 Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives (RAOs) used at the time of the remedy selection still valid? .........................................................................................................54 7.2.1 Changes in Standards and To-Be-Considered Criteria (TBCs) ..............................54 7.2.2 Changes in Exposure Pathways, Toxicity, and Other Contaminant Characteristics56 7.2.3 Exposure Pathways.................................................................................................56 7.2.4 Toxicity Factors .......................................................................................................56 7.2.5 Changes in Risk Assessment Methods...................................................................56 7.2.6 Expected Progress towards Meeting RAOs ............................................................57 7.3 Question C: Has any other information come to light that could call into question the protectiveness of the remedy?.............................................................57 ii Table of Contents, Continued 8.0 Issues .............................................................................................................................58 8.1 Issue 1: Institutional Control Verification – Zoning ......................................................58 8.2 Issue 2: Institutional Control Verification – Deed Restriction.......................................58 8.3 Issue 3: Exposition ‘D’ Zone Concentrations...............................................................58 9.0 Recommendations ........................................................................................................59 10.0 Protectiveness Statement ............................................................................................60 11.0 Next Review...................................................................................................................61 12.0 References.....................................................................................................................62 Figures 1-1 Site Map 4-1 Pemaco Site Groundwater and Vapor-Extraction System 4-2 Site Plan with All Monitoring and Extraction Wells 6-1 Recent TCE Detections above 25 µg/L 6-2 Pre-HVDPE Maximum Concentrations of TCE in Exposition ‘A’ Zone Groundwater, Pemaco Superfund Site, Maywood CA 6-3 Post-ERH Maximum Concentrations of TCE in Exposition ‘A’ Zone Groundwater, Pemaco Superfund Site, Maywood CA 6-4 Pre-HVDPE Maximum Concentrations of TCE in Exposition ‘B’ Zone Groundwater, Pemaco Superfund Site, Maywood CA 6-5 Post-ERH Maximum Concentrations of TCE in Exposition ‘B’ Zone Groundwater, Pemaco Superfund Site, Maywood CA 6-6 Pre-HVDPE Maximum Concentrations of TCE in Exposition ‘C’ Zone Groundwater, Pemaco Superfund Site, Maywood CA 6-7 Post-ERH Maximum Concentrations of TCE in Exposition ‘C’ Zone Groundwater, Pemaco Superfund Site, Maywood CA 6-8 TCE Concentrations in Exposition ‘C’ Zone Groundwater 6-9 TCE Concentrations in Exposition ‘D’ Zone Groundwater 6-10 D-zone Map 7-1 City of Maywood Municipal Wells iii Table of Contents, Continued Tables 2-1 Chronology of Site Events 4-1 SSRLs Specified in the 2005 ROD 4-2 Current Groundwater and Soil-Vapor Monitoring Program 4-3 Maintenance Log Summary: Significant O&M Activities at Pemaco Superfund Sitefrom 2007 – 2010 4-4 Summary of O&M Costs at Pemaco Superfund Site 6-1 Pre-HVDPE and Post-ERH Maximum Concentrations of Select COCs: Perched Zone Groundwater 6-2 Pre-HVDPE and Post-ERH Maximum Concentrations of Select COCs: Exposition ‘A’ Zone Groundwater 6-3 Pre-HVDPE and Post-ERH Maximum Concentrations of Select COCs: Exposition ‘B’ Zone Groundwater 6-4 Pre-HVDPE and Post-ERH Maximum Concentrations of Select COCs: Exposition ‘C’ Zone Groundwater 6-5 Pre-HVDPE and Post-ERH Maximum Concentrations of Select COCs: Exposition ‘D’ Zone Groundwater 7-1 Optimization Opportunities 7-2 Groundwater Analytical Results, March 2010 8-1 Issues and Recommendations Appendices A Public Notifications