Site Name: DOVER MUNICIPAL LANDFILL
EPA ID: NHD980520191 EPA Region: 01 Metro Statistical Area: 6450
TOLEND RD, DOVER, NH 03820
Site Description: OWNED BY CTY OF DOVER 55 ACRES. ACCEPTED DRUMMED WASTES & LOOSE TRASH OF SOLIDS, LIQS & SLUDGES WH WERE DUMPED OR INCINRON SITE BEFORE CLOSURE IN 1979.PROBLEMS ASSOCD W/SWAMPS & HI GW TABLE ORGANIC CONTAM OF GRND & SURF WATERS.
Operable Unit:
ROD ID: EPA/ROD/R01-91/062 ROD Date: 09/10/91
Contaminant: VOCS; BENZENE; PCE; TCE; TOLUENE; VINYL CHLORIDE; ORGANICS; METALS; ARSENIC
Keys: NONE
Abstract:
THE 55-ACRE DOVER MUNICIPAL LANDFILL SITE IS AN INACTIVE LANDFILL IN DOVER, STRAFFORD COUNTY, NEW HAMPSHIRE. LAND USE IN THE AREA IS RURAL-RESIDENTIAL AND RECREATIONAL. THE SITE OVERLIES BOTH AN UPPER AND A LOWER AQUIFER THAT ARE SEPARATED BY IMPERMEABLE CLAY. SIGNIFICANT NEARBY SURFACE WATER BODIES INCLUDE THE BELLAMY RESERVOIR LOCATED 2,000 FEET SOUTH OF THE SITE, WHICH SUPPLIES DRINKING WATER FOR LOCAL MUNICIPALITIES; THE CALDERWOOD WELL, WHICH SUPPLIES DRINKING WATER FOR THE CITY OF DOVER, AND IS LOCATED APPROXIMATELY ONE-HALF MILE NORTH OF THE LANDFILL; AND THE COCHECO RIVER, WHICH RUNS APPROXIMATELY 500 FEET EAST OF THE LANDFILL. A PORTION OF THE SITE LIES WITHIN THE 100-YEAR FLOODPLAIN OF THE COCHECO RIVER, AND FOUR WETLAND SYSTEMS ARE IN THE VICINITY OF THE SITE. FROM 1960 UNTIL 1979, THE LANDFILL ACCEPTED MUNICIPAL AND INDUSTRIAL WASTES INCLUDING DRUMMED MATERIALS AND LIQUID WASTES. LANDFILL DISPOSAL PRACTICES INCLUDED TRENCHING, BURNING, AND FILL AND COVER METHODS. BETWEEN 1980 AND 1982, THE FACILITY WAS CAPPED AND CLOSED, AND A DRAINAGE CHANNEL WAS EXCAVATED AROUND THE LANDFILL TO INTERCEPT LEACHATE. IN 1981, VOC CONTAMINATION WAS FOUND IN PRIVATE RESIDENTIAL WELLS SCREENED IN THE UPPER AQUIFER IN THE VICINITY OF THE LANDFILL. FURTHER ANALYSES IDENTIFIED TWO CONTAMINANT PLUMES, ONE MIGRATING TO THE SOUTH AND THE OTHER MOVING TO THE EAST. THIS RECORD OF DECISION (ROD) ADDRESSES BOTH SOURCE CONTROL AND MANAGEMENT OF MIGRATION OF CONTAMINATED GROUND WATER, AS A FINAL REMEDY. THE PRIMARY CONTAMINANTS OF CONCERN AFFECTING THE SOIL, SEDIMENT, SLUDGE, DEBRIS, AND GROUND WATER ARE VOCS INCLUDING BENZENE, PCE, TCE, TOLUENE AND VINYL CHLORIDE; OTHER ORGANICS; AND METALS INCLUDING ARSENIC. THE SELECTED REMEDIAL ACTION FOR THIS SITE INCLUDES EXCAVATING AND CONSOLIDATING APPROXIMATELY 300 CUBIC YARDS OF SEDIMENT FROM THE DRAINAGE CHANNEL, AND DEPOSITING THE MATERIAL INTO THE LANDFILL PRIOR TO CAPPING; RECONTOURING AND CAPPING THE LANDFILL WITH A MULTI-MEDIA CAP INCLUDING INSTALLING A PASSIVE VENTING SYSTEM FOR METHANE GAS; GROUND WATER PUMPING AND ONSITE TREATMENT OF THE SOUTHERN PLUME GROUND WATER AND LEACHATE USING AERATION FOR VOC REMOVAL, CARBON ADSORPTION TO REMOVE OTHER ORGANICS, AND FLOCCULATION, COAGULATION, AND PRECIPITATION, FOLLOWED BY DISCHARGE OF THE TREATED WATER ONSITE TO SURFACE WATER OR OFFSITE TO THE DOVER PUBLICLY OWNED TREATMENT WORKS (POTW); DISPOSING OF RESIDUAL SLUDGE OFFSITE; CONSTRUCTING A CLEAN GROUND WATER DIVERSION SYSTEM UPGRADIENT OF THE SITE; NATURAL ATTENUATION OF THE EASTERN PLUME GROUND WATER; CONSTRUCTING A SURFACE WATER RUNON/RUN-OFF DIVERSION SYSTEM; CONDUCTING LONG-TERM GROUND WATER MONITORING; AND IMPLEMENTING INSTITUTIONAL CONTROLS, INCLUDING DEED AND GROUND WATER USE RESTRICTIONS. IF IT IS DETERMINED THAT THE SELECTED GROUND WATER TREATMENT REMEDY FOR THE SOUTHERN PLUME IS NOT EFFECTIVE, A CONTINGENCY REMEDY THAT UTILIZES PRECIPITATION AND AIR STRIPPING WILL BE IMPLEMENTED. THE ESTIMATED PRESENT WORTH COST FOR THIS REMEDIAL ACTION IS $24,155,700, WHICH INCLUDES AN ANNUAL O&M COST OF $157,680 FOR 10 YEARS AND AN ANNUAL COST FOR GROUND WATER MONITORING OF $721,600 FOR 30 YEARS. PERFORMANCE STANDARDS OR GOAL; SEDIMENT IN AREAS WHERE ARSENIC LEVELS ARE ABOVE 50 MG/KG WILL BE EXCAVATED AND CONSOLIDATED UNDER THE LANDFILL CAP. GROUND WATER INTERIM CLEAN-UP GOALS ARE BASED ON THE MORE STRINGENT OF FEDERAL MCLS OR NON-ZERO MCLGS, EPA HEALTH ADVISORIES, STATE STANDARDS, OR REFERENCE DOSES, AND INCLUDE ARSENIC 50 UG/L (RCRA MCL) OR BACKGROUND, WHICHEVER IS HIGHER, BENZENE 5 UG/L (MCL), PCE 5 UG/L (MCL), AND TCE 5 UG/L (MCL). THE FINAL GROUND WATER CLEAN-UP LEVELS WILL BE DETERMINED AS A RESULT OF A RISK ASSESSMENT PERFORMED ON RESIDUAL GROUND WATER AFTER ALL INTERIM CLEAN-UP LEVELS HAVE BEEN MET.
Remedy:
THIS ROD SETS FORTH THE SELECTED REMEDY FOR DOVER MUNICIPAL LANDFILL SITE, WHICH ADDRESSES SOURCE CONTROL AND MANAGEMENT OF MIGRATION TO MEET CLEANUP GOALS. THE SELECTED REMEDY IS MULTI-TASKED. THE REMEDIAL MEASURES WILL PROTECT THE DRINKING WATER AQUIFER BY MINIMIZING FURTHER MIGRATION OF CONTAMINANTS TO THE GROUNDWATER AND SURFACE WATER, WILL ELIMINATE THREATS POSED BY DIRECT CONTACT WITH OR INGESTION OF CONTAMINATED SOILS AND WASTES AT THE SITE AND WILL PREVENT THE INGESTION AND DIRECT CONTACT WITH CONTAMINATED GROUNDWATER AND SURFACE WATER. THE MAJOR COMPONENTS OF THE SELECTED REMEDY INCLUDE:
* RECONTOURING OF THE EXISTING LANDFILL;
* CONSOLIDATION OF SEDIMENTS IN THE PERIMETER DRAINAGE DITCH;
* LIMITED EXCAVATION AND CONSOLIDATION OF SEDIMENTS IN THE DRAINAGE SWALE AND AT THE CONFLUENCE TO THE COCHECO RIVER;
* CAPPING OF THE LANDFILL;
* UPGRADIENT GROUNDWATER DIVERSION;
* GROUNDWATER/LEACHATE COLLECTION AND TREATMENT;
* PRE-DESIGN STUDIES WHICH INCLUDE THE INSTALLATION OF ADDITIONAL MONITORING WELLS;
* NATURAL ATTENUATION OF THE "EASTERN" PLUME;
* GROUNDWATER EXTRACTION AND TREATMENT OF THE "SOUTHERN" PLUME;
* LONG-TERM ENVIRONMENTAL MONITORING;
* INSTITUTIONAL CONTROLS, WHERE POSSIBLE.