For the Frontera Creek Site and Remedial Objectives Were Established for Mercury in Soils and Sediments
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x_^. DECLARATION-?O3 THE RECORD OF DECISION SITE NAME AND LOCATION Frontera Creek Site - Humacao, Puerto Rico STATEMENT OF BASIS AND PURPOSE This decision document presents the selected remedial action for the Frontera Creek Superfund Site, in Humacao, Puerto Rico, which was chosen in accordance with the requirements of the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) as amended by the Superfund Amendments- and Reauthorization Act of 1986 ("SARA") and the National Oil ;and Hazardous Substances Pollution Contingency Plan ("NCP"). This decision document summarizes the factual and legal basis for selecting the remedy for this site. The Commonwealth of Puerto Rico Environmental Quality Board ("EQB") concurs with the selected remedy. A letter of concurrence from EQB is appended to this document. The information supporting this remedial action decision is contained in the administrative record for this site, an index of which is appended to this document. ^^ ASSESSMENT OF THE SITE Actual or threatened releases of hazardous substances from this site, if not addressed by implementing the response action selected in this Record of Decision ("ROD"), may present an imminent and substantial threat to public health, welfare, or the environment. DESCRIPTION OF THE SELECTED REMEDY This action addresses the threats posed by the Site by excavating mercury contaminated sediments and soils at the Site. The major components of the selected remedy include: 0 Excavation of 370 cubic yards of mercury-contaminated sediments in the Technicon ditch. 0 Excavation of 180 cubic yards of mercury-contaminated soils at the Technicon facility surroundings. 0 Dewatering and containment of excavated material. g o 0 Off-site disposal of excavated material at a RCRA Subtitle D or C waste facility. o to •v ^x ° Pretreatment of wastewater generated from dewatering and discharge to Technicon's wastewater treatment plant, a local ° •u 10 ._ POTW, or an on-site treatment plant. 0 Performance of confirmatory soil sampling in the remediated areas to verify that mercury concentrations in residual, on- site materials do not exceed the remedial action objective of 35 ppm. 0 Regrading and revegetating the remediated areas. DECLARATION OF STATUTORY DETERMINATIONS The selected remedy is protective of human health and the environment, complies with Federal and State requirements that are legally applicable or relevant and appropriate to the remedial action, and is cost effective. This remedy utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable for this site. However, because treatment of the principal threats at the site was not found to be practicable, this remedy does not satisfy the statutory preference for treatment as a principal element of the remedy. As this remedy will result in no hazardous substances remaining on-site above health-based levels, a five year review is not required. .,• <• ^Eonstantine "Sidamon-ErisXes^f Date f ^ Regional Administrator/y-rr ' / / o o <s\O •U OJ TABLE OF CONTENTS DECISION SUMMARY PAGE I. SITE LOCATION AND DESCRIPTION ....................... 1 II. SITE HISTORY AND ENFORCEMENT ACTIVITIES.............. 2 III. HIGHLIGHTS OF COMMUNITY PARTICIPATION................ 4 IV. SCOPE AND ROLE OF RESPONSE ACTION.................... 4 V. SUMMARY OF SITE CHARACTERISTICS...................... 4 VI. SUMMARY OF SITE RISKS................................ 9 VII. DESCRIPTION OF REMEDIAL ALTERNATIVES................. 12 VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES...... 17 I.. DESCRIPTION OF THE SELECTED REMEDY................... 22 .. STATUTORY DETERMINATIONS............................. 22 ATTACHMENTS APPENDIX A FIGURES APPENDIX B TABLES APPENDIX C COMMONWEALTH OF PUERTO RICO ENVIRONMENTAL QUALITY BOARD LETTER OF CONCURRENCE APPENDIX D RESPONSIVENESS SUMMARY APPENDIX E ADMINISTRATIVE RECORD INDEX o o O 0% DECISION SUMMARY FRONTERA CREEK SITE HUMACAO, PUERTO RICO UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION II NEW YORK o o o\ *> (Jl :/*"""V' I. SITE LOCATION AND DESCRIPTION The Frontera Creek Site (the "Site") is located on the eastern coast of Puerto Rico within the Municipality of Humacao at approximately 18°9' north latitude and 65*47' west longitude. A site location map is provided as Figure 1. The Site includes Frontera Creek from east of Junquito Ward to its entry into the Caribbean Sea; the 13 industrial properties adjacent to the creek; the North, Southeast and Southwest Frontera lagoons also known as the Santa Teresa Lagoons; their associated abandoned pump stations which were used to keep the lagoons dry for agricultural purposes and the Ciudad Cristiana housing development located alongside the creek. Land use in the area surrounding the site consists of mixed residential, industrial and wildlife refuge. The section of Frontera Creek within the study area extends for a distance of approximately three miles from Route 925 to El Morrillo, where it enters the Caribbean Sea. It is a small channelized drainage ditch that varies from 3 to 45 feet in width and from about 0.3 to 6 feet in depth. The creek channel runs past the 13 site industries, under Route 3 and then past Ciudad Cristiana before bisecting the Frontera Lagoons and intersecting the Caribbean Sea at El Morrillo. f~*^ Downstream of Route 3, in-stream flow is negligible and the creek consists primarily of stagnant pools. Except for the section from the pump station to the sea, the entire creek within the study area flows through a man-made channel, constructed prior to the 1960s to improve coastal drainage. The creek runs between thr^e large shallow freshwater lagoons which are currently owned by the Puerto Rico Department of Natural Resources (DNR). These lagoons, which cover an area of approximately 200 acres, are in hydraulic connection under the creek. In the early 1930s the section of Frontera Creek's channel from Route 3 to the Santa Teresa pump station was constructed and the lagoon areas were drained for agricultural purposes, including sugarcane, coconut and livestock production. When the drainage pumps located at the Santa Teresa pump station ceased operations in 1979, the coastal lagoons refilled and now support an abundant and varied aquatic wildlife community. The DNR acquired the lagoons in 1984 and the area is now a wildlife refuge. The Mandri Canal was originally.constructed to drain the wetlands nj north of Route 3, including the Mandri Lagoon. As shown on 3 Figure l, the portion of the canal within the study area is on DNR property and extends from Route 3 to the Santa Teresa pump ' 0 station. This canal is approximately 20 feet wide and 20 feet ^ ^^^ deep and appears to be a healthy ecosystem as evidenced by an r^: abundance of wildlife and species diversity. The Mandri Canal o was included in the study area, since it has been alleged ^ o\ that, the waters of the canal are in hydraulic connection with the creek and Frontera lagoons. According to the 1980 Census, the total population of the Municipality of Humacao was 51,402. The Site lies within the Humacao River watershed located on the southeastern coast of Puerto Rico. Low-lying hills and small mountains of Cretaceous igneous deposits with steep slopes are found a short distance inland from the coast. These elevations comprise the borders of the Humacao River watershed. Frontera Creek runs parallel to and lies north of the Humacao River. Frontera Creek runs approximately 3.82 miles from the hills northwest of Rio Abajo to its outlet in the Caribbean Sea. The head of the creek originates at an elevation of approximately 230 feet. The creek runs southeast 1.09 miles to Route 925 which marks the start of the coastal plain at an elevation of around 16 feet above sea level and the edge of the study area. From there . it continues east 2.73 miles to the sea. Frontera Creek drains a 2,540 acre watershed into the sea at a location just north of El Morillo. Groundwater occurs in the alluvial aquifer under water table conditions. Although the alluvial sediments do not have hydraulic characteristics generally associated with a productive aquifer, five industrial wells and one agricultural well are reportedly in use at the site. The Site is underlain by Quaternary Age alluvial deposits. These deposits consist primarily of brown and gray clay and silty clay, interbedded with brown and gray fine to coarse sand. These sediments overlie and grade .into beach deposits near the coast. The alluvial deposits are underlain by the igneous bedrock. For the purpose of this document, the Frontera Creek drainage system is defined as the waters of Frontera Creek, the Frontera lagoons and the Mandri Canal. The entire system contains extensive lagoons, mangrove stands, swamps, grasslands, coconut groves, estuaries and saltwater marshes. The entire lagoon system covers an area of about 500 acres. It is a nesting ground for the endangered West Indian whistling duck, brown pelican, as well as several other species that are considered rare in Puerto Rico, such as the ruddy duck and the pied-billed grebe. ——II—. ——————————————————————————.———————————SITE HISTORY AND ENFORCEMENT ACTIVITIE— S . g3 Industrial wastewaters from industries within the Site were discharged into the creek from 1971 to 1981. Public concern ° about the site arose in 1977 following the death of thirty cows to that grazed in the area. Since that time, the area has been investigated by EPA, EQB and several industries located in the ^ vicinity. These investigations confirmed the presence of contaminants including mercury in sediments and surface water samples. Several industries, including Technicon Electronics, (formerly a subsidiary of Revlon, Inc.), which used mercury in its manufacturing process, previously discharged their waste water directly into Frontera Creek. The EQB fined Technicon in June 1978 for this practice. Technicon stopped its mercury discharges into Frontera Creek in 1978. As a result of the potential threat to public health, in August 1983, the Frontera Creek Site was included on EPA's National Priorities List of hazardous waste sites. From 1978 to 1980, a housing development, Ciudad Cristiana, was built along Frontera Creek.