Site Name: BURLINGTON NORTHERN (SOMERS PLANT)
EPA ID: MTD053038386 EPA Region: 08 Metro Statistical Area:
SEC 23-25,R21W,T27W, SOMERS, MT 59932
Operable Unit:
ROD ID: EPA/ROD/R08-89/023 ROD Date: 09/27/89
Contaminant: ORGANICS; PAHS; PHENOLS; METALS; ZINC
Keys: BIODEGRADATION; CARCINOGENIC COMPOUNDS; CLEAN WATER ACT; DIRECT CONTACT; EXCAVATION; FLOODPLAIN; GROUND WATER; GROUND WATER MONITORING; GROUND WATER TREATMENT; INSTITUTIONAL CONTROLS; MCLS; METALS; ONSITE DISCHARGE; ONSITE DISPOSAL; ONSITE TREATMENT; O&M; ORGANICS; PAHS; PHENOLS; PLUME MANAGEMENT; RCRA; SAFE DRINKING WATER ACT; SEDIMENT; SOIL; STATE STANDARDS/REGULATIONS; TREATABILITY STUDIES; TREATMENT TECHNOLOGY; WETLANDS
Abstract:
THE 80-ACRE BURLINGTON NORTHERN (SOMERS PLANT) SITE IS A FORMER RAILROAD TIE TREATMENT FACILITY IN SOMERS, FLATHEAD COUNTY, MONTANA. RESIDENTIAL AREAS BORDER THE SITE ON THREE SIDES AND WETLANDS ARE LOCATED ALONG FLATHEAD LAKE, 1,200 FEET TO THE EAST, AND IN A SLOUGH AREA ADJACENT TO THE PLANT. FLATHEAD LAKE IS CURRENTLY THE SOURCE OF THE SOMERS MUNICIPAL DRINKING WATER SUPPLY. BURLINGTON NORTHERN OPERATED THE TREATMENT PLANT FROM 1901 TO 1986 AND GENERATED WASTEWATER PRIMARILY CONSISTING OF STREAM CONDENSATE CONTAINING ZINC CHLORIDE AND CREOSOTE, WHICH WAS DISCHARGED TO A LAGOON SOUTH OF THE TREATMENT BUILDING. OVERFLOW FROM THE LAGOON FLOWED THROUGH AN OPEN DRAINAGE DITCH TO A POND WHICH FORMED IN A SWAMP AREA ADJACENT TO THE DITCH, AND EVENTUALLY INTO THE LAKE. CONTAMINATED SOIL AND SEDIMENT AREAS IN ADDITION TO THE DRAINAGE DITCH, SWAMP POND, AND LAGOON INCLUDE A DRIPPAGE AREA ALONG THE RAILROAD TRACKS WHERE TREATED TIES WERE REMOVED FROM THE TREATMENT BUILDING, A SLOUGH AREA WHERE TREATED TIES WERE STORED, AND A BEACH AREA EXTENDING INTO FLATHEAD LAKE. GROUND WATER IN THE VICINITY OF THE LAGOON AND THE SWAMP POND IS ALSO CONTAMINATED. IN MAY 1985 EPA PERFORMED AN EMERGENCY REMOVAL ACTION AND REMOVED APPROXIMATELY 3,000 CUBIC YARDS OF CONTAMINATED SOIL AND 100,000 GALLONS OF CONTAMINATED WATER FROM THE SWAMP POND AND DRAINAGE DITCH AREAS. THE EXCAVATED AREAS WERE BACKFILLED AND COVERED, AND EXCAVATED SOIL WAS TRANSFERRED TO AN OFFSITE RCRA-REGULATED FACILITY TO AWAIT TREATMENT. CONTAMINATED WATER WAS TREATED ONSITE TO RECOVER USABLE MATERIALS. THE PRIMARY CONTAMINANTS OF CONCERN AFFECTING THE SOIL, SEDIMENT, AND GROUND WATER ARE ORGANICS INCLUDING CREOSOTE CONSTITUENTS SUCH AS PAHS AND PHENOLS, AND METALS INCLUDING ZINC.
THE SELECTED REMEDIAL ACTION FOR THIS SITE INCLUDES EXCAVATION AND ONSITE BIOLOGICAL TREATMENT OF 11,700 CUBIC YARDS OF CONTAMINATED SOIL AND SEDIMENT FROM ALL SOURCE AREAS EXCEPT THE BEACH AREA; ONSITE RESTORATION OR REPLACEMENT OF WETLANDS AREAS; INSTALLATION AND OPERATION OF AN INNOVATIVE HOT WATER FLUSHING SYSTEM AND A WATER TREATMENT SYSTEM USING OZONE/UV OR PEROXIDE/UV IN THE LAGOON AND SWAMP POND AREAS TO TREAT CREOSOTE CONTAMINATED GROUND WATER, AND IN-SITU BIOLOGICAL TREATMENT TO DEGRADE RESIDUAL CONTAMINANTS IN THE GROUND WATER AND CONTAMINANTS ADSORBED ONTO THE AQUIFER MATRIX; GROUND WATER WILL BE REINJECTED OR DISCHARGED TO A POTW; GROUND WATER MONITORING; AND IMPLEMENTATION OF TEMPORARY INSTITUTIONAL CONTROLS TO RESTRICT GROUND WATER USE. THE ESTIMATED TOTAL PRESENT WORTH COST FOR THIS REMEDIAL ACTION IS $12,031,000, WHICH INCLUDES AN ANNUAL O&M COST OF $661,000 FOR YEARS 1-2, $811,000 FOR YEARS 3-10, AND $72,000 FOR YEARS 11-30. THE PRESENT WORTH COST INCLUDES REMEDIATION OF BEACH SEDIMENTS. UNDER THE SELECTED ACTION, BEACH SEDIMENTS ARE LEFT IN PLACE. REDUCING THIS COST BY A VOLUME RATIO GIVES APPROXIMATELY $11,000,000.
Remedy:
THIS RESPONSE ACTION IS ANTICIPATED TO BE THE FINAL ACTION FOR THE SITE. OTHER ACTIONS AT THE SITE INCLUDED THE 1985 SUPERFUND EMERGENCY REMOVAL IN THE SWAMP POND AREA (SEE FIGURE 3 IN THE RECORD OF DECISION SUMMARY FOR LOCATIONS OF AREAS OF THE SITE), AFTER IT WAS DETERMINED TO CONSTITUTE AN IMMINENT AND SUBSTANTIAL HAZARD TO FLATHEAD LAKE, AND THE CLOSURE IN 1988 OF TWO WASTEWATER IMPOUNDMENTS AT THE SITE UNDER STATE RESOURCE CONSERVATION AND RECOVERY ACT (RCRA) AUTHORITY.
THIS RESPONSE ACTION ADDRESSES THE REMAINING CONTAMINATION BY REMEDIATING SOILS, SEDIMENTS AND GROUND WATER, ALL OF WHICH HAVE BEEN DETERMINED TO POSE A POTENTIAL THREAT TO HUMAN HEALTH AND THE ENVIRONMENT. THE SELECTED REMEDY ADDRESSES THE PRINCIPAL THREATS BY REMOVING THE POTENTIAL FOR DIRECT CONTACT WITH SOILS, BY REDUCING THE IMPACT OF THE SOILS AND SEDIMENTS ON GROUND WATER AND SURFACE WATER, AND BY TREATING THE GROUND WATER.
SOILS AND SEDIMENTS - THE MAJOR ASPECTS OF THE SELECTED "SOURCE CONTROL" OR SOIL COMPONENT OF THE REMEDY INCLUDE:
* EXCAVATION OF APPROXIMATELY 11,700 CUBIC YARDS OF CONTAMINATED SOILS AND SEDIMENTS. VOLUMES TO BE EXCAVATED INCLUDE SOILS ABOVE THE WATER TABLE FROM THE CERCLA LAGOON, DRIP TRACK, DRAINAGE DITCH AND BENEATH THE RETORT BUILDING AS WELL AS SEDIMENTS FROM THE SLOUGH.
* ON-SITE BIOLOGICAL TREATMENT OF EXCAVATED SOILS.
* RESTORATION AND/OR REPLACEMENT OF WETLANDS LOST DURING REMEDIAL ACTION AND THOSE LOST DURING THE 1985 EMERGENCY ACTION. THE RESTORATION/REPLACEMENT WILL BE CONDUCTED IN CONSULTATION WITH THE US DEPARTMENT OF THE INTERIOR.
GROUND WATER - THE MAJOR ASPECTS OF THE "MIGRATION CONTROL" OR GROUND WATER COMPONENT OF THE SELECTED REMEDY INCLUDE:
* INSTALLATION AND OPERATION OF AN INNOVATIVE HOT WATER FLUSHING AND WATER TREATMENT SYSTEM TO REMOVE AND TREAT AVAILABLE FREE CREOSOTE CONTAMINATION FROM THE WATER TABLE AQUIFER IN THE CERCLA LAGOON AND SWAMP POND AREAS.
* IN-SITU BIOLOGICAL TREATMENT TO DEGRADE BOTH CONTAMINANTS ADSORBED ONTO THE AQUIFER MATRIX AND RESIDUAL CONTAMINANTS DISSOLVED IN THE GROUND WATER.
GROUND WATER RESTRICTIONS - CURRENTLY, THERE ARE NO DRINKING WATER SUPPLY WELLS IN THE AFFECTED PORTIONS OF THE WATER TABLE AQUIFER. HOWEVER, INSTITUTIONAL CONTROLS DESIGNED TO PROHIBIT THE CONSTRUCTION OF NEW WELLS DOWNGRADIENT FROM THE CERCLA LAGOON AND IN THE SWAMP POND AREA WILL BE IMPLEMENTED AND MAINTAINED UNTIL GROUND WATER QUALITY RETURNS TO ACCEPTABLE LEVELS.
MONITORING - THE GROUND WATER COMPONENT OF THE SELECTED REMEDY WILL REQUIRE MONITORING TO ASSURE THAT TREATMENT IS EFFECTIVE AND THAT TREATMENT PROCEEDS UNTIL RISK-BASED CLEANUP LEVELS HAVE BEEN ACHIEVED AND MAINTAINED. IN ADDITION, MONITORING OF THE TOWN'S PROPOSED NEW MUNICIPAL WELLS IN THE BEDROCK AQUIFER WILL BE INSTITUTED IF TESTING INDICATES THAT DRAWDOWN IN THESE WELLS COULD CAUSE THE CONTAMINATED WATER TABLE AQUIFER TO AFFECT THE MUNICIPAL SUPPLY. THE MUNICIPAL WELLS ARE EXPECTED TO BE INSTALLED AND TESTED IN THE FALL OF 1989.
CONTINGENCY REMEDIES - THE SELECTED GROUND WATER COMPONENT OF THE REMEDY INVOLVES TWO INNOVATIVE TECHNOLOGIES: HOT WATER FLUSHING AND IN-SITU BIOLOGICAL TREATMENT. THESE TECHNOLOGIES ARE EXPECTED TO BE SUCCESSFUL AT THE SITE. HOWEVER, BECAUSE OF THEIR UNPROVEN NATURE UNDER THE SOMERS HYDROGEOLOGIC CONDITIONS, THESE TECHNOLOGIES WILL REQUIRE PILOT TESTING TO DETERMINE THEIR EFFECTIVENESS PRIOR TO FULL-SCALE IMPLEMENTATION.
CONTINGENCY REMEDY A. - IF EPA DETERMINES, BASED ON PILOT TESTING, THAT GROUND WATER REMEDIATION IS NOT PRACTICABLE, SOILS WILL BE EXCAVATED TO A DEPTH OF APPROXIMATELY 20 FEET IN THE SWAMP AREA AND TO APPROXIMATELY 30 FEET IN THE CERCLA LAGOON AREA, AND DOWNGRADIENT. THIS EXCAVATION WILL REMOVE HE SOURCE OF GROUND WATER CONTAMINATION BOTH ABOVE AND BELOW THE WATER TABLE, IN ADDITION TO THE EXCAVATION AREAS OUTLINED IN THE SELECTED REMEDY. IN THIS CASE, INSTITUTIONAL CONTROLS DESIGNED TO PREVENT THE CONSTRUCTION OF DRINKING WATER WELLS DOWNGRADIENT FROM THE CERCLA LAGOON WILL BE IMPLEMENTED AND MAINTAINED UNTIL NATURAL DEGRADATION RETURNS THE AQUIFER TO A USABLE CONDITION. UNDER THIS CONTINGENCY, THE EXCAVATED SOILS WILL BE INCINERATED ON-SITE.
CONTINGENCY REMEDY B. - IF, BASED ON PILOT TESTING, EPA DETERMINES THAT GROUND WATER REMEDIATION WOULD ONLY BE PRACTICABLE IN THE AREA OF THE CERCLA LAGOON BUT NOT IN THE SWAMP AREA, MOST LIKELY DUE TO LOWER PERMEABILITY AQUIFER MATERIALS, THE SWAMP AREA SOILS WILL BE EXCAVATED TO A DEPTH OF APPROXIMATELY 20 FEET, IN ADDITION TO THE EXCAVATION AREAS OUTLINED IN THE SELECTED REMEDY. THE GROUND WATER COMPONENT OF THE SELECTED REMEDY WILL THEN BE IMPLEMENTED IN THE CERCLA LAGOON AREA ONLY. UNDER THIS CONTINGENCY REMEDY THE SOILS WILL ALSO BE INCINERATED ON-SITE.