VOLUME I REMEDIAL INVESTIGATION DOVER MUNICIPAL LANDFILL DOVER, NEW HAMPSHIRE Prepared for: New Hampshire Department of Environmental Services Waste Management Division Concord, New Hampshire Prepared by: Goldberg-Zoino & Associates, Inc. Manchester, New Hampshire and Wehran Engineers and Scientists Methuen, Massachusetts November 1988 GZA File No. D-5159 WE Project No. 05216 WEHRAN ENGINEERS & SCIENTISTS November 10, 1988 Mr. Richard H. Pease, P.E. On-Scene Coordinator State of New Hampshire Department of Environmental Services Waste Management Division 6 Hazen Drive, P.O. Box 96 Concord, NH 03301 RE: Remedial Investigation Report Dover Municipal Landfill Dover, NH WE Project No. 05216 Dear Richard: Attached please find ten (10) copies of the final remedial investigation report for the above referenced project. This report has addressed all review comments received from New Hampshire Department of Environmental Services (NHDES) personnel and the United States Environmental Protection Agency (USEPA). Per our telephone conversation, Section 8.0 Public Health Risk Assessment has been submitted as a modified draft for NHDES/USEPA final review and will be submitted as an addendum after receipt and incorporation of any review comments you may have. We would like to take this opportunity to thank you and other representatives of NHDES/USEPA for your contribution to the Remedial Investigation effort. Should you have any further questions or if we can be of any further assistance, please contact this office. Very truly yours, WEHRAN ENGINEER!! RATION Ha Associate Goldberg, Zoino and Associates Patrick G. Gillespie, P.E. Vice President New England Regional Offices 100 MILK STREET, METHUEN, MA 01844 • (617) 682-1980 TABLE OF CONTENTS DOVER REMEDIAL INVESTIGATION Page EXECUTIVE SUMMARY 1.0 INTRODUCTION 1-1 1.1 STUDY OBJECTIVES 1-1 1.2 SITE BACKGROUND INFORMATION 1-2 1.2.1 Site Description 1-2 1.2.2 Site History and Operations 1-5 1.2.3 Previous Site Investigators 1-7 1.3 HISTORICAL ASSESSMENT OF THE PROBLEM 1-9 2.0 SITE FEATURES INVESTIGATION 2-1 2.1 DEMOGRAPHIC SETTING 2-1 2.2 LAND USE AND NATURAL RESOURCES 2-1 2.3 CLIMATOLOGY 2-3 3.0 HAZARDOUS SUBSTANCES SURVEY 3-1 4.0 HYDROGEOLOGIC INVESTIGATION PROGRAM 4-1 4.1 GEOLOGIC RECONNAISSANCE AND FRACTURE TRACE ANALYSIS 4-2 4.1.1 Geologic Reconnaissance 4-2 4.1.2 Fracture Trace Analysis 4-3 4.2 RESIDENTIAL WELL SURVEY 4-3 4.3 GEOPHYSICAL EXPLORATIONS 4-4 4.3.1 Seismic Refraction Survey 4-5 4.3.2 Electromagnetic Survey 4-5 4.3.3 Magnetometer Survey 4-6 4.3.4 Electrical Resistivity Survey 4-6 4.4 TEST PIT EXPLORATIONS 4-6 4.5 TEST BORINGS 4-7 )NTENTS (continued) 4.5.1 Drilling Procedure s 4-8 4.5.2 Soil Sampling 4-9 4.5.3 Bedrock Drillin gand Sampling 4-9 4.6 GROUNDWATER MONITORING WELL INSTALLATIONS 4-10 4.7 IN-SITU HYDRAULIC CONDUCTIVITY TESTS 4-12 4.7.1 In-situ Overburden Hydraulic Conductivity Tests 4-12 4.7.2 In-situ Bedrock Pressure Tests 4-13 4.8 LABORATORY SOILS TESTS 4-13 4.8.1 Laboratory Soil Gradation Analyses 4-13 4.8.2 Laboratory Triaxial Hydraulic Conductivity Tests 4-14 4.8.3 Standard Index Laboratory Analyses 4-14 4.8.4 Cation Exchange 4-14 4.9 SURFACE WATER STATIONS 4-15 4.10 SOIL AND SEDIMENT SAMPLING AND ANALYSIS 4-15 4.11 GROUNDWATER AND SURFACE WATER SAMPLING AND ANALYSIS 4-18 5.0 SITE GEOLOGY AND HYDROLOGY 5-1 5.1 SURFICIAL AND BEDROCK GEOLOGY 5-1 5.1.1 Bedrock Geology 5-1 5.1.2 Surficial Geology 5-6 5.2 SURFACE WATER HYDROLOGY 5-13 5.2.1 Cocheco River 5-15 5.2.2 Bellamy Reservoir 5-16 5.3 GROUNDWATER HYDROLOGY 5-17 5.3.1 Hydrogeologic Setting 5-17 5.3.2 Hydraulic Properties 5-18 5.3.3 Groundwater Level sand Flow Directions 5-21 5.3.4 Hydraulic Gradien tand Groundwater 5-28 Seepage Velocities 5.3.5 Groundwater Flo wModel 5-30 6.0 AIR MONITORING PROGRAM 6-1 TABLE OF CONTENTS (continued) 6.1 INITIAL AIR MONITORING 6-1 6.2 AI RSAMPLING BY THE STATE OF NEW HAMPSHIRE 6-1 6.3 AIR SAMPLING BY THE US EPA 6-2 6.4 REMEDIAL INVESTIGATION AIR MONITORING PROGRAM 6-3 7.0 DISTRIBUTION AND MIGRATION OF CONTAMINANTS 7-1 7.1 OBSERVED CONTAMINANTS 7-1 7.1.1 Volatile Organic Compound s 7-2 7.1.2 Acid and Base/Neutral Extractable Organic Compounds 7-2 7.1.3 Metal s 7-3 7.2 OBSERVED DISTRIBUTION OF CONTAMINANTS 7-4 7.2.1 Surface Water and Sediments 7-4 7.2.2 Groundwater 7-7 7.2.3 Soils 7-12 7.2.4 Air 7-14 7.2.5 Summary 7-14 7.3 CONTAMINANT TRANSPORT 7-15 7.3.1 Groundwater Contaminant Transport and Attenuation Mechanisms 7-16 7.3.2 Site Contaminant Migration Patterns 7-20 7.3.3 Groundwater Contaminant Transport Analysis 7-27 8.0 PUBLIC HEALTH RISK ASSESSMENT PUBLISHED AS SEPARATE DOCUMENT 9.0 IDENTIFICATION OF POTENTIALLY APPLICABLE REMEDIAL TECHNOLOGIES 9-1 9.1 GENERAL RESPONSE ACTIONS 9-1 9.2 POTENTIALLY APPLICABLE REMEDIAL TECHNOLOGIES 9-2 9.2.1 Lan dUse Restrictions 9-2 9.2.2 Alternate Water Suppl y 9-3 9.2.3 Continued Monitorin g 9-3 9.2.4 Surface Barrier s 9-3 TABLE OF CONTENTS (continued) 9.2.5 Removal and Containment of Contaminated Sediments 9-4 9.2.6 Subsurface Barriers 9-5 9.2.7 Excavatio n 9-6 9.2.8 Groundwater Extraction 9-7 9.2.9 Liquid Treatmen t 9-7 9.2.10 Hazardous Solids Treatment 9-9 9.2.11 Hazardous Solids Disposal 9-9 9.2.12 Gas Migration Control 9-9 9.3 PRELIMINARY SCREENING OF REMEDIAL TECHNOLOGIES 9-11 10.0 SUMMARY AND CONCLUSIONS 10-1 10.1 BACKGROUND 10-1 10.2 HYDROGEOLOGIC CONDITIONS 10-2 10.3 NATURE AND DISTRIBUTION OF ENVIRONMENTAL CONTAMINATION 10-3 11.0 RECOMMENDATIONS FOR ADDITIONAL EXPLORATIONS AND ANALYSIS 11-1 11.1 MARINE CLAY EXPLORATIONS 11-1 11.2 POSSIBLE ADDITIONAL SOURCE AREAS 11-2 11.3 CONTINUED SITE MONITORING 11-2 11.4 ADDITIONAL AIR MONITORING AND WETLANDS ASSESSMENT 11-3 BIBLIOGRAPHIC REFERENCES TABLES TABLE 1 REMEDIAL INVESTIGATION TASKS TABLE 2 INDUSTRIAL WASTE SURVEY TABLE 3 SUMMARY OF GROUNDWATER ELEVATIONS TABLE 4 SUMMARY OF SURFACE WATER ELEVATIONS TABLE 5 SUMMARY OF HYDRAULIC CONDUCTIVITIES - IN-SITU ANALYSIS TABLE 6 SUMMARY OF HYDRAULIC CONDUCTIVITIES - KOZENY-CARMAN ANALYSIS TABLE OF CONTENTS (continued) TABLE 7 SUMMARY OF HYDRAULIC CONDUCTIVITIES - TRIAXIAL LABORATORY ANALYSIS TABLE 8 GROUNDWATER FLOW MODEL - UPPER AQUIFER CALIBRATION TABLE 9 GROUNDWATER FLOW MODEL - LOWER AQUIFER CALIBRATION TABLE 10 DOVER - GROUNDWATER FLOW MODEL SENSITIVITY ANALYSIS ­ RECHARGE UPPER LAYER TABLE 11 DOVER - GROUNDWATER FLOW MODEL SENSITIVITY ANALYSIS ­ RECHARGE LOWER LAYER TABLE 12 DOVER - GROUNDWATER FLOW MODEL SENSITIVITY ANALYSIS ­ HYDRAULIC CONDUCTIVITY TABLE 13 DOVER - GROUNDWATER FLOW MODEL SENSITIVITY ANALISIS ­ TRANSIMISSIVITY TABLE 14 DOVER - GROUNDWATER FLOW MODEL SENSITIVITY ANALYSIS ­ BOUNDARY TABLE 15 SUMMARY OF CHEMICAL ANALYSIS PERFORMED TABLE 16 SUMMARY OF VOLATILE ORGANIC COMPOUNDS OBSERVED­ GROUNDWATER TABLE 17 SUMMARY OF VOLATILE ORGANIC COMPOUNDS OBSERVED­ SURFACE WATER TABLE 18 SUMMARY OF VOLATILE ORGANIC COMPOUNDS OBSERVED - SOIL AND SEDIMENT TABLE 19 SUMMARY OF METALS OBSERVED - CONCENTRATIONS GREATER THAN MAXIMUM CONTAMINANT LEVELS - GROUNDWATER AND SURFACE WATER TABLE 20 SUMMARY OF METALS OBSERVED - CONCENTRATIONS GREATER THAN MAXIMUM ANTICIPATED BACKGROUND CONCENTRATIONS­ SOIL TABLE 21 SUMMARY OF ACID AND BASE/NEUTRAL EXTRACTABLE COMPOUNDS OBSERVED - GROUNDWATER TABLE 22 SUMMARY OF ACID AND BASE/NEUTRAL EXTRACTABLE COMPOUNDS OBSERVED - SOIL TABLE 23 CONTAMINANT TRANSPORT MODEL - PREDICTED CONTAMINANT CONCENTRATIONS VS. FIELD DATA - TOTAL VOC's j: op CONTENTS (continued) TABLE 24 CONTAMINANT TRANSPORT MODEL - PREDICTED CONTAMINANT CONCENTRATIONS VS. FIELD DATA - METHYL ISOBUTYL KEYTONE TABLE 25 CONTAMINANT TRANSPORT MODEL - PREDICTED CONTAMINANT CONCENTRATIONS VS. FIELD DATA - TOLUENE TABLE 26 GENERAL RESPONSE ACTIONS AND ASSOCIATED REMEDIAL TECHNOLOGIES TABLE 27 SITE CHARACTERISTICS THAT MAY AFFECT REMEDIAL TECHNOLOGY SELECTION TABLE 28 WASTE CHARACTERISTICS THAT MAY AFFECT REMEDIAL TECHNOLOGY SELECTION FIGURES FIGURE 1 LOCUS PLAN FIGURE 2 EXPLORATION LOCATION PLAN FIGURE 3 LOCATION PLAN - RESIDENTIAL WELLS FIGURE 4 SUBSURFACE PROFILE A-A1 FIGURE 5 SUBSURFACE PROFILE B-B1 FIGURE 6 SUBSURFACE PROFILE C-C1 FIGURE 7 SUBSURFACE PROFILE D-D1 FIGURE 8 ESTIMATED EXTENT OF MARINE CLAY UNIT FIGURE 9 BEDROCK ELEVATION CONTOUR PLAN FIGURE 10 LOCATION PLAN - THE HOPPERS OBSERVATION WELLS FIGURE 11 GROUNDWATER ELEVATION CONTOUR PLAN - UPPER HYDROGEOLOGIC UNIT FIGURE 12 GROUNDWATER ELEVATION CONTOUR PLAN - LOWER HYDROGEOLOGIC UNIT FIGURE 13 TOTAL VOLATILE ORGANIC COMPOUNDS IN GROUNDWATER AND SURFACE WATER - UPPER HYDROGEOLOGIC UNIT FIGURE 14 TOTAL VOLATILE ORGANIC COMPOUNDS IN GROUNDWATER - LOWER HYDROGEOLOGIC UNIT TABLE OF CONTENTS (continued) FIGURE 15 ESTIMATED ZONE OF LANDFILL CONTAMINATION - GROUNDWATER - UPPER HYDROGEOLOGIC UNIT FIGURE 16 GROUNDWATER FLOW MODEL - UPPER LAYER BOUNDARIES FIGURE 17 GROUNDWATER FLOW MODEL - LOWER LAYER BOUNDARIES FIGURE 18 MODEL CALIBRATION - UPPER LAYER HYDRAULIC CONDUCTIVITIES FIGURE 19 MODEL CALIBRATION - UPPER LAYER SATURATED THICKNESS FIGURE 20 MODEL CALIBRATION - VERTICAL HYDRAULIC CONDUCTANCES FIGURE 21 MODEL CALIBRATION - LOWER LAYER TRANSMISSIVITIES FIGURE 22 MODEL CALIBRATION - SIMULATED UPPER LAYER GROUNDWATER ELEVATION CONTOURS FIGURE 23 MODEL CALIBRATION - SIMULATED LOWER LAYER GROUNDWATER ELEVATION CONTOURS FIGURE 24 SOURCE LOADING AREA - UPPER MODEL LAYER FIGURE 25 PREDICTED CONTAMINANT PLUME, 1987 - UPPER LAYER - NO RETARDATION FIGURE 26 PREDICTED CONTAMINANT PLUME, 1997 - UPPER LAYER - NO RETARDATION FIGURE 27 PREDICTED CONTAMINANT PLUME, 2027 - UPPER LAYER - NO RETARDATION FIGURE 28 PREDICTED CONTAMINANT PLUME, 1987 - UPPER LAYER­ RETARDATION = 2.0 FIGURE 29 PREDICTED CONTAMINANT PLUME,