report: record of decision scorpio recycling inc. site ... · cfr part 300. this decision ......
TRANSCRIPT
SDMS Document
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 2
NEW YORK, NEW YORK
95814
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RECORD OF DECISION SCORPIO RECYCLING INC. SITE
OPERABLE UNIT 1 (GROUDWATER) TOA BAJA, PUERTO RICO
SEPTEMBER 2006
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Scorpio Recycling, Inc. Site Operable Unit 1 (Groundwater) Toa Baja, Puerto Rico
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the Scorpio Recycling, Inc. Site (the "Site") Operable Unit 1 (Groundwater), located in the Municipality of Toa Baja, Puerto Rico, which was chosen in accordance with the requirements of the Comprehensive Environmental Response, Compensation and Liability Act of 1980 ("CERCLA"), 42 U.S.C. § 9601-9675, as amended, and the National Oil and Hazardous Substances Pollution Contingency Plan ("NCP"), 40 CFR Part 300. This decision document explains the factual and legal basis for selecting the remedy for the Site. The information supporting this remedial action decision is contained in the administrative record for the Site. The administrative record index is attached (Appendix 1).
The Puerto Rico Environmental Quality Board ("EQB") concurs with the selected remedy (Appendix II).
DESCRIPTION OF THE SELECTED REMEDY - NO ACTION
This selected remedy addresses the fate and transport of the contaminants in the groundwater emanating from the Site. The United States Environmental Protection Agency ("EPA"), in consultation with EQB, has determined that Site-related groundwater contamination is limited and does not pose a significant threat to human health or the environment; therefore, remediation is not necessary.
This determination is based on the results of the Remedial Investigation which did not identify contaminants above screening criteria in Site monitoring wells or supply wells. In addition, the Baseline Human Health Risk Assessment indicates that the levels of contaminants present in the groundwater at the Site fall within the acceptable levels and do not present a risk. The No Action decision for groundwater complies with Federal and Commonweallh requirements that are legally applicable or relevant and appropriate to the remedial action and is cost effective
As such, the No Action decision for groundwater is protective of human health and the environment.
DECLARATION
In accordance with the requirements of CERCLA, as amended, and the NCP, EPA, in consultation with EQB, has determined that the Scorpio Recycling Site: Operable Unit 1 (Groundwater), does not pose a significant threat to human health or the environment; therefore, no remedial action is necessary for the groundwater at the Site.
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Because this remedy results in hazardous substances remaining in soils on the Site above levels that allow for unlimited use and unrestricted exposure, a review will be conducted within five years to ensure that the remedy is protective of human health and the environment.
(V ' George Pavlou, Director Date Emergency and Remedial Response Division
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 2
NEW YORK, NEW YORK
DECISION SUMMARY
RECORD OF DECISION SCORPIO RECYCLING, INC.SITE
OPERABLE UNIT 1 GROUNDWATER
TOA BAJA, PUERTO RICO
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TABLE OF CONTENTS
SITE NAME, LOCATION AND DESCRIPTION 2
SITE HISTORY AND TIME-CRITICAL REMOVAL ACTION 2
HIGHLIGHTS OF COMMUNITY PARTICIPATION ....4
SCOPE AND ROLE OF ACTION , 5
REMEDIAL INVESTIGATION 5
GROUNDWATER SAMPLING AND ANALYTICAL RESULTS 9
CONCLUSIONS OF THE REMEDIAL INVESTIGATION 11
SUMMARY OF SITE RISKS 11
SUMMARY OF THE SELECTED NO ACTION REMEDY 14
DOCUMENTATION OF SIGNIFICANT CHANGES ..14
APPENDIX I. ADMINISTRATIVE RECORD INDEX 15
APPENDIX II. PUERTO RICO ENVIRONMENTAL QUALITY BOARD LETTER OF CONCURRENCE 16
APPENDIX III. FIGURES 17
APPENDIX IV TABLES 18
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SITE NAME, LOCATION AND DESCRIPTION
The Scorpio Recycling, Inc. (SRI) Site is located on State Road 2 at kilometer 19.7, interior (Acuna Street), in the Candelaria Ward of Toa Baja, Puerto Rico. The Site is approximately four miles west of the town of Bayamon and lies within a chain of rugged limestone hills (known as mogotes) which flank the southern margin of the Atlantic coastal plain of northern Puerto Rico (Figure 1).
The Site is surrounded by other industries and warehouses. To the northeast is Casa de Renovaci6n (Former Villa Real Dance Sal6n). To the north is a Texaco gas station and Alpha Casting Company. To the south is a ravine leading to a sinkhole and Mitsubishi Motors Company. To the west are La Rosa Del Monte Express, Inc. and Auto Cells, Inc. To the east is a karst hill where Pan American Gun is located at the top (Figure 2). The Site is currently active with approximately 40 workers. Approximately 900 people live within 0.25 mile of the Site; 46,197 people live within one mile of tiie Site (EPA 2000). The population within a four-mile radius is about 154,773.
Metal recycling operations are currently conducted at the facility by Scrapyard Metal Recycling, Inc. The Site is owned by Scorpio Recycling, Inc. which formerly conducted operations at the facility. Atsur Metals, Inc. is a former owner and operator of the facility. The Site includes a relatively flat 9-acre parcel which slopes gently to the north within its northern portion and to the south in its southern portion. An administrative office, aluminum processing and compacting buildings, a maintenance shop, and a metal accumulation building are located at the Site. A ditch located along the northeast area of the Site collects runoff from the northern portion of the Site and drains toward State Road 2 and Acufia Sfreet.
SITE HISTORY AND TIME-CRITICAL REMOVAL ACTION
During the facility's early operation, crushing batteries to recover the lead for recycling was a common practice. This practice resulted in sulfiaric acid spills onto the ground. Acid runoff from the area where the batteries were handled flowed down into the sinkhole located adjacent to this crushing area. The sinkhole served as a collection point for surface runoff where it could then infiltrate into the groundwater. Battery recycling and crushing were reported to have stopped in 1983.
In October 1999, a Hazard Ranking System (HRS) Report was prepared for the Site (Weston 1999). The HRS is a structured evaluation process that evaluates the groundwater, surface water and air contaminant migration pathways and the soil exposure pathway at a site. The HRS is the primary means for evaluating sites for inclusion on EPA's National Priorities List (NPL). The HRS indicated that the Site is in a karst recharge area and located near drinking water sources. It also described populations served by those drinking water sources, and the soil contamination on the Site which were the primary factors for recommending the Site for inclusion on the NPL. In addition, the presence of a sinkhole raised a concern since it may provide a conduit for Site-related contamination to enter the water-bearing aquifer in the area which is used for drinking. The acidic soils detected at the Site can also enhance the
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migration of lead into the groundwater.
On February 4,2000, the Site was listed as a final site on the NPL. EPA's Superfund program initiated a Remedial Investigation for groundwater and EPA's Removal program conducted a Removal Action to remove contaminated soil from the battery crushing area.
There is a long history of environmental problems and poor housekeeping practices at the Site including complaints of burning of scrap and automobile batteries, and discharges of battery acids, oil and other waste material into the sinkhole. A summary of the previous investigations conducted by EPA and Puerto Rico Environmental Quality Board (EQB) are presented below.
In 1991, EQB conducted a Preliminary Assessment and Site Inspection at the Site. This identified poor housekeeping practices including stained and corroded floors, spills, batteries on the ground and on pallets, lead battery cells open to the atmosphere, acidic runoff flowing into the sinkhole area, and stressed vegetation.
Sampling activities conducted by EQB in March 1994, indicated metal contamiriation in surface soils at concentrations greater than three times background at selected locations. Semi-volatile organic compounds (SVOCs), pesticides, and polychlorinated biphenyls (PCBs) were also detected. Groundwater (tap water) samples were collected from one upgradient (background) well and a downgradient supply well. These analyses identified lead in the downgradient supply well (Campanilla 7) at a concentration of one-half the drinking water standard, although lead was also detected in the associated field blanks during this event. At the time of the EQB Site Inspection, the batteries were shipped unbroken to Brazil; however, poor handling practices continued to result in battery acid being spilled onto the ground.
EPA's Technical Assistance Team (TAT) sampled soil and runoff/leachate into the sinkhole in October 1991 and July 1993. Results showed high concentrations of barium, lead, and vanadium above the EPA's Soil Screening Levels for ingestion. In addition, water samples were collected from a series of small puddles in the area. The metals detected in the surface water included lead, antimony, cadmium, copper, nickel, silver, vanadium, zinc, and iron. The average pH in the water samples was 5, indicating acidic conditions.
An Expanded Site Inspection (ESI) was conducted by EPA in April 1999 to gather additional data for use in the HRS evaluation of the Site and to support the need for a Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Removal Action. Sampling involved the collection of surface and subsurface soil from the battery crushing area and other areas throughout the Site, as well as groundwater samples from a nearby well (Pepsi 1). The ESI documented surface and subsurface metal contamination and volatile and semi-volatile organic contamination in soils at concentrations up to three times greater than background. Groundwater results did not detect any notable contamination.
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EPA performed additional sampling in September 1999 to evaluate the extent of contamination associated with the former battery crushing operation in the southwestern section of the facility. Surface and subsurface soil samples were collected. The study concluded that elevated concentrations of lead and PCBs were present. All other organics (volatile organic compounds (VOCs), SVOCs, pesticides, and dioxins/furans) were detected at relatively low concentrations.
In 2002, EPA began a Removal Action to excavate and remove the battery cases, miscellaneous debris and soil contamination in the southwest portion of the Site and the sinkhole. Approximately 15,000 tons of soil were excavated and removed from the battery crushing area and the slope leading down to the sinkhole. Contaminated soil was stabilized with trisodium phosphate (TSP) prior to disposal at a landfill.
EPA conducted on-site X-Ray Fluorescence (XRF) screening analysis of soil samples for lead and cadmium during removal activities. The purpose of this sampling was to evaluate the remaining lead and cadmium contamination in the excavation area and to determine parameters for the treatment (stabilization) of contaminated soil. Samples were collected to determine if the cleanup level of 400 parts per million (ppm) had been achieved for lead. Lead concentrations ranged from non-detect to 94,300 ppm.
Sampling results indicated that the entire source had not been removed. Waste, which EPA believes is associated with metal recycling operations, remains buried under the Rosa del Monte storage shed building and portions of the adjacent paved Rosa del Monte parking lot. No Removal Action was performed in the large scrap pile areas. Removal actions ceased in June 2004.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Remedial Investigation ("RI") Report, the Baseline Human Health Risk Assessment, and the Proposed Plan for Operable Unit 1 (Groundwater) were released for a 30-day public comment on August 21, 2006. These documents along with the Administrative Record were made available to the public in the EPA Docket Room in Region 2, New York, Toa Baja Municipal Library, EQB's Superfund File Room and EPA Caribbean Environmental Protection Division's Office. A public notice announcing the availability of these documents and the date of the public meeting was published in the El Nuevo Dia newspaper on August 21,2006, the San Juan Star on August 21, 2006, and in the El Todo Norte newspaper on August 23, 2006. The comment period ended on September 21, 2006.
During the comment period, EPA held a public meeting to present the results of the RI, the Baseline Human Health Risk Assessment and the Proposed Plan, to respond to questions regarding these documents, and to receive both oral and written comments. EPA held the public meeting at the Casa de Renovacion, former Salon Villa Real, Route No. 2, km. 19.5, Bo Candelaria, Toa Baja, Puerto Rico on September 5,2006. No comments or questions where raised at the meeting and no written comments were submitted to EPA during the public comment period. As such, there is no Responsiveness Summary attached to this ROD.
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SCOPE AND ROLE OF ACTION
EPA began field activities for the RI in August 2002. The purpose of the RI was to gather sufficient data to characterize the extent of contamination and to characterize potential risks to human receptors associated with groundwater. In addition, the RI focused on collecting adequate groundwater data to determine if the Site soil contamination had impacted groundwater and, if so, the nature and extent of that contamination.
Conclusions of the RI Report indicate, along with those from past sampling activities, that the groundwater immediately beneath and downgradient of the Site are all below screening criteria. In addition, potential future impacts from the Site have been minimized by EPA's removal of a large part of the contaminated sources from 2002 through 2004. The waste remaining in the battery source area is currently underneath a paved parking lot and building, thereby minimizing infiltration into the groundwater.
The conclusions of the Baseline Human Health Risk Assessment indicate that the carcinogenic risks were within EPA's acceptable risk range of 10"* to 10"* for current and future residents and non-carcinogenic hazards for exposures at the Site showed values below EPA's target Hazard Index of 1 for current and future residents. Given these results, the risk analyses indicate that the groundwater at the Site and off the Site does not pose unacceptable carcinogenic risks or non-carcinogenic health hazards for future Site workers and future residential adults and children.
REMEDIAL INVESTIGATION
The following describes the regional and Site-specific geography, geology, and hydrogeology as presented in published reports and the RI field program.
Topography
The Site is part of the eastern edge of the karst terrain of the North Coast Limestone Province (f^P). The topography of the NLP region is characterized by the presence of large-scale karst weathering and dissolution features, including closed drainage depressions, sinkholes (dolines) and rugged limestone hills (mogotes). The prominent karst features in the vicinity are mogotes, an open-ended sinkhole valley, and thick layers of blanket deposits, consisting mostly of silty clay.
Based on the USGS 7.5 minute Bayamon Quadrangle topographic map, the Site generally slopes gently towards the north at an elevation of about 246 feet (75 meters) above mean sea level (amsl). However, an open-ended sinkhole valley is adjacent to the southwestern property boundary. The sinkhole is approximately 70 feet (21 meters) below the grade of the Site and receives storm water runoff from a hillside slope leading from the southwestern portion of the Site. Beyond the Site boundary to the northwest, south and southwest, isolated mogotes rise over 160 feet (50 meters) above the Site's elevation, up to about 490 feet (150 meters) amsl.
The topography of the land further west is dominated by rugged karst features and the deeply incised valley of the Rio de la Plata. The topography to the north is generally flat, with the
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land gently rising towards a prominent east-west chain of mogotes located about one mile (2.5 kilometers) to the north of the Site. The chain of mogotes, which defines the southern margin of the flat-lying Atlantic coastal plain, is over 300 feet (100 meters) above sea level in places. The coastal plain is characterized by large low-lying wetland areas, small tributary streams, drainage canals, and poorly-drained undeveloped land. The Atlantic Ocean is approximately four miles (6.4 kilometers) north of the Site.
Geology
Puerto Rico is divided into three geologic provinces, an older Cretaceous-age central volcanic-plutonic province trending east to west and two younger Tertiary limestone provinces along its northern and southern coastal margins. The Site is situated along the north-central coast of Puerto Rico, and lies within the NLP.
The bedrock formations of the NLP are of late-middle Tertiary age (early Miocene). These rocks consist of a sequence of limestones and terrigenous sediments of Oligocene to Pliocene age that strike east-west and normally dip two to five degrees to the north. The limestone succession unconformably overlies Cretaceous volcanic basement rocks. Within the area of the Bayamon topographic quadrangle, the sequence is divided into six formations. In order of decreasing age, the formations are the San Sebastian Formation, Lares Limestone, Mucarabones Sand, Cibao Formation, Aguada Limestone, and Aymamon Limestone. Figure 3 is a generalized east-west geologic section illustrating the variation in formation thickness across the study area (Threster 1999). Some of these units are described briefly below:
Mucarabones Sand. The oldest unit in this sequence in the Bayamon area is the Oligocene (possibly Miocene) age Mucarabones Sand (Monroe 1980), sometimes referred to as the San Sebastian Formation (e.g., Rodriguez-Martinez 1995). The Mucarabones Sand consists . primarily of cross-bedded greyish-orange and yellow fine-to medium-grained sand. The maximum thickness of the unit is about 400 feet (120 meters) in the center of the Bayamon quadrangle. The unit thins to below 320 feet (100 meters) towards the west and east.
Cibao Formation. The early Miocene age Cibao Formation overlies the Lares Limestone west of the Bayamon area and grades laterally (eastwards) into the Mucarabones Sand. The Cibao Formation is a heterogeneous unit consisting of "intergradational and interlensing bed of calcareous clay, limestone, sandy clay, sand, sandstone, and gravel" (Monroe 1980). The unit consists of four members: the Rio Indio Limestone (recognized in the southwestern portion of the Bayamon sheet); the Quebrada Arenas Limestone Member (outcropping across the central portion of the Bayamon sheet); the Miranda Sand Member (a discontinuous sand unit found in channels eroded into the top of the Quebrada Arenas Limestone Member); and the informally named upper member. The total thickness of the Cibao Formation ranges from over 490 feet (150 meters) west of the Bayamon area to about 160 feet (50 meters) at the eastern edge of the Bayamon area.
Aguada Limestone. The middle Miocene Aguada Limestone conformably overlies the Cibao Formation and the contact between them is gradational. The unit thins from west to east, from approximately 200 feet (60 meters) at the western side of the study area to less than 115 feet (35 meters) on the eastern edge of the area. The unit consists of a fine to medium-grained calcarenite, with some quartz sand. The uppermost portion of the Aguada Limestone is
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usually thin bedded and cross laminated.
Aymamon Limestone. The middle Miocene Aymamon Limestone conformably overlies the Aguada Limestone and is about 650 feet (200 meters) thick. The Aymamon Limestone is a thick-bedded and massive dense limestone, calcarenite, and dolomite. Where exposed in the study area, it forms the rugged doline hills (mogotes) which border the coastal plain.
Unconsolidated Quaternary Deposits. Unconformably oyerlying the limestones in some low-lying areas of the NLP are Quaternary clastic deposits consisting of reddish clays or sandy clays and sands. This unit, commonly termed "blanket sands", ranges in thickness from 0 to 100 feet (30 meters).
In addition to the blanket sands, a variety of recent alluvial deposits also are found along major river valleys and near the coast, including river terrace deposits, deltaic, mud flat, and beach deposits, and eolianites (wind-blown deposits).
Surface Water Hydrology
The Site is located in the eastem edge of the karst belt within the Rio de la Plata drainage area which is characterized by mogotes, flat plains of blanket sand/clay deposits and relatively few sinkholes. There are no surface water bodies on the Site. Due to the thickness of the blanket clay deposits and the amount of paved areas in the vicinity sloping to the north, most precipitation flows overland along open and closed stormwater drains toward Puerto Rico Route 2 to the north where it merges with regional overland flow to the west. This flow pattern was noted during heavy rain events at the Site. Small amounts of runoff may flow toward the south down a slope to the sinkhole where it ponds on the clay deposits and slowly evaporates and/or seeps into the surface soils.
The nearest surface water is the Quebrada Mejico, a small westward-flowing tributary stream of the Rio de la Plata, located about one-half mile south and upgradient of the Site.
The deeply incised valley of the Rio de la Plata is located approximately 1.5 miles to the west and sidegradient of the Site. Groundwater from beneath the Site flows in a north-northwest direction and is not expected to discharge to Rio de la Plata. The Rio de la Plata is a large northward flowing river that enters the coastal plain approximately two miles northwest of the Site. The Rip de la Plata flows northward another four miles across the coastal plain and empties into the Atlantic Ocean at Punta Boca Juana, approximately five miles northwest of the Site. The Rio de la Plata is classified by EQB as a Class SC water body, which means its waters are intended for use as a raw water source for potable water supply.
The coastal plain, approximately 1.5 miles north and downgradient of the Site, is characterized by large wetland areas, small tributary streams, drainage canals, and poorly-drained undeveloped land. Groundwater discharges to these surface water features. Groundwater that flows beneath the Site will merge with other groundwater from the region . before it reaches these discharge points.
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Hydrogeology
Upper Aquifer
The regional hydrogeology around the Site is characterized by an upper unconfined aquifer composed of the permeable parts of the Cibao Formation, the Aguada Limestone, the Aymamon Limestone, and the upper permeable parts of the overlying unconsolidated deposits. Vertical groundwater flow is limited by the relatively impermeable part of the Cibao Formation, which forms the lower boundary of the upper aquifer along the southern portion of the study area (Troester 1999). A lower artesian (confined) aquifer is present below the impermeable part of the Cibao Formation.
The base of the upper aquifer primarily is defined by the uppermost strata of terrestrial elastics and argillaceous limestone of the upper member of the Cibao Formation (Rodriguez-Martinez 1995). The upper aquifer is limited in thickness northwards to the coast by an underlying saltwater zone, which is thought to encroach as much as three miles inland of the coast. Therefore, the thickness of the upper aquifer increases southward as far as the outcrop of the lower confining unit within the Cibao Formation.
The elevation of the upper aquifer's water table surface is controlled by the surface topography and surface drainage features such as major rivers. Figure 4 illustrates the configuration of the water table within the study area (Anderson 1976), showing the water table roughly parallels the land surface. For example, the east-west trending chain of mogotes running through the center of the study area is underlain by a corresponding ridge in the water table. The predominant flow direction in the study area is northward, toward the coastal plain. Where the aquifer is dissected by stream channels, groundwater discharges into the channels.
In general, transmissivity values range from 200 square feet per day (ft^/day) to over 500 ft̂ /day. Transmissivity is lowest in the Cibao Formation and highest in the Aymam6n Limestone, especially near the contact with the Aguada Limestone. Transmissivity is much lower near the coast. Well yields in the upper aquifer in the municipal well fields of Campanilla and Sabana Seca, along the southern margin of the cpastal plain, are in the remge of 30 gallons per minute (gpm) to 2,500 gpm.
The karst hills in which the Site is located are the primary recharge area for the upper aquifer. Recharge to the upper aquifer formations occurs principally by rainfall in the limestone outcrop area and by infiltration of streamflow; discharge is primarily into wetlands along the coastal plain. However, in mogote areas, recharge by direct infiltration through the relatively impermeable blanket sand deposits or the recrystallized weathered surfaces of the exposed limestone is limited (Monroe 1966). The majority of recharge occurs from runoff during large rainfall events when runoff from the mogote surface quickly flows into holes and solution channels around the base of the mogotes and recharges the aquifer (Monroe 1976). Water levels in wells in mogote areas have been observed to respond immediately to rainfall events (Troester 1999).
In the Dorado area, less than 10 miles west of the study area, the lower confining unit of the upper aquifer consists of the upper member of the Cibao Formation, and the underlying Quebrada Arenas and Rio Indio Limestone Members, a thickness of about 600 feet (200
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meters). In Rio Piedras, about 10 miles east of the study area, the confining unit has thinned to about 225 feet (70 meters) (Rodriguez-Martinez 1995). The confining unit is thought to be of a leaky nature, allowing slow vertical migration of groundwater from the lower aquifer to the upper aquifer.
Lower Aquifer
The lower aquifer of the North Coast Limestone contains water under artesian pressure throughout the area where it is overlain by the semi-confining unit. Where the aquifer crops out, in the recharge areas near the southernmost outcrop belt of the mid-Tertiary sequence, the lower aquifer contains water under atmospheric conditions.
The lower aquifer includes the Mucarabones Sand, a calcareous marine sandstone, with local lenses of volcanic conglomerate, and, in the southwest of the study area, the age-equivalent Lares Limestone. Water in the lower aquifer ranges from fresh to brackish. Reported transmissivity values for the Mucarabones Semd range from 850 to 1,000 ft^/day (Anderson 1976). The lower aquifer becomes progressively thicker and more transmissive towards the west, beyond the study area.
GROUNDWATER SAMPLING AND ANALYTICAL RESULTS
Under the supervision of EPA, with support from the EQB, the RI was performed to determine the nature and extent of groundwater contamination at the Site. EPA began RI field activities at the site in August 2002. The purpose of the RI was to gather sufficient data to characterize the extent of contamination and to characterize potential risks to human receptors associated with groundwater.
The Site is in the eastem edge of the karst terrain of the North Limestone Province and is underlain by two karst bedrock formations, the Aguada Limestone and Cibao Formations, comprising the shallow unconfined aquifer system. The prominent karst features near the Site are mogotes, an open-ended sinkhole valley, and thick layers of blanket deposits, consisting mostly of silty clay. Depth to water ranges from approximately 190 feet below ground surface at the Site to 63 feet adjacent to the sinkhole/mogote area.
Groundwater flow beneath the sinkhole is expected to be complex due to groundwater mounding. Groundwater may flow radially outward after heavy rainfall events but is generally expected to mimic topography and flow downgradient to the north/northwest, similar to the regional groundwater flow.
During high rainfall events, the mechanism of rapid infiltration will dominate in the sinkhole/mogote complex. However, during low rainfall periods, the mechanism of slow seepage of water through the clay layer at the sinkhole bottom will dominate.
As part of this RI, seven groundwater monitoring wells were installed at the Site to depths from approximately 90 feet in the Mitsubishi Motors Company area to 240 feet in the Site area (Figure 5). EPA conducted two rounds of groundwater sampling. The first round was conducted in February 2005 and the second round in April 2005. For each'round, samples were collected from the seven newly-installed monitoring wells and three existing off-site
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supply wells; Pepsi 1, Campanilla 1 and Campanilla 7 (Figure 6). Two supply wells were sampled during each round of sampling: Pepsi 1 and Campanilllas 7 in Round 1, and " Campanulas 1 and Campanulas 7 in Round 2.
During Round 1, seven of the inorganic analytes detected during the pre-remedlal soil investigation at levels above the soil screening level for migration to groundwater were also detected during the groundwater sampling. They included: arsenic, barium, cadmium, chromium, lead, nickel and selenium. Other analytes also detected were thallium and antimony. The method detection limits for thallium and antimony, available at the time of the Round 1 sampling event and the Roimd 2 sampling event, were above the screening criteria. No other contaminants exceeded screening criteria in any of the moiutoring wells or the three supply weUs during the Round 1 sampling event.
During Round 2, eight inorganics were detected in Site monitoring wells and the two supply wells: aluminum, calcium, chromium, iron, magnesium, manganese, potassiiun, and sodium. A few of these analytes were detected at levels significantly above background levels but below the screening criteria.
A third round of groundwater sampling was conducted between May 31 and June 9, 2006 as a supplement to the RI. The third round of groundwater sampling utilized the lower detection limits for thallium and antimony to determine if screening criteria were exceeded. Groundwater samples were collected from the six monitoring wells, two public supply wells and the Pepsi well. Bis(2-ethylhexyl)phthalate, a common laboratory blank contaminant, was detected above screening criteria (15 ug/L) at MW-3A during the supplemental sampling event. No other contaminants exceeded screening criteria in any of the Site monitoring wells or the supply wells. The two analytes that were also detected, antimony and thallium, in Rounds 1 and 2 were not detected above screening criteria during Round 3.
The established regulatory standards and criteria, known as chemical-specific applicable or relevant and appropriate requirements (ARARs), used to screen for regulatory exceedances were the EPA National Primary Drinking Water Regulations (Maximum Contaminant Levels) and the Puerto Rico Water Quality Standards (PRWQS).
No contaminants exceeded screening criteria in any of the monitoring wells or the three supply wells during the Round 1, Round 2, or Round 3 sampling events (Figures 7-9). Factors such as sorption to soil, depth to the groundwater table, neutralization of acid by carbonate rock and soil, and the thickness of the clay layer may be mitigating the impact of contaminants to the groundwater.
Given these results, along with those from past sampling activities, the groundwater immediately beneath and downgradient of the Site are all below screening criteria. In addition, potential fiiture impacts from Site sources have been minimized by EPA's removal of a large part of the contaminated sources from 2002 through 2004. The waste remaining in the battery source area is currently underneath a paved parking lot and building and thus, migration of contaminants from the source areas is expected to be minimal.
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CONCLUSIONS OF THE REMEDLU. INVESTIGATION
Based upon the RI conducted for the groundwater at the Site, EPA with EQB's concurrence, has determined that no contaminants exceeded the screening criteria in any of the Site's monitoring wells or the three supply wells during the three rounds of sampling events. In addition, potential future impacts from Site sources have been minimized by EPA's removal of a large portion of the contaminated sources from 2002 through 2004.
Scorpio Recycling, Inc. is still an active operating scrap metal facility. As such, scrap, metals, and other materials are brought to the facility, separated into various types, and then moved off the facility to other metals refining/reprocessing facilities throughout the world. Because waste materials are constantly being moved at the facility, EPA cannot currently conduct an investigation of the soils beneath the waste piles or the existence of buried waste. These contaminant sources will be investigated as part of Operable Unit 2 (Soils) for the Site.
SUMMARY OF SITE RISKS
Based upon the results of the RI, a baseline human health assessment and an ecological risk evaluation were conducted to estimate the risks associated with current and fiiture Site conditions. A baseline human health risk assessment is an analysis of the potential adverse human health caused by hazardous substance exposure from a site in the absence of any actions to control or mitigate such exposure under current and future land uses.
Baseline Human Health Risk Assessment
A four-step process is utilized for assessing site-related human health risks for reasonable maximum exposure scenarios.
Hazard Identification: In this step, the contaminants of concern (COCs) at the site in various media (i.e., soil, groundwater, surface water, and air) are identified based on such factors as toxicity, frequency of occurrence, and fate and transport of the contaminants in the environment, concentrations of the contaminants in specific media, mobility, persistence, and bioaccumulation.
Exposure Assessment: In this step, the different exposure pathways through which people might be exposed to the contaminants identified in the previous step are evaluated. Examples of exposure pathways include incidental ingestion of and dermal contact with contaminated soil. Factors relating to the exposure assessment include, but are not limited to, the concentrations to which people may be exposed and the potential frequency and duration of exposure. Using these factors, a "reasonable maximum exposure" scenario, which portrays the highest level of human exposure that could reasonably be expected to occur, is calculated.
Toxicity Assessment: In this step, the types of adverse health effects associated with contaminant exposures and the relationship between magnitude of exposure and severity of adverse health effects are determined. Potential health effects are contaminant-specific and may include the risk of developing cancer over a lifetime or other non-cancer health effects, such as changes in the normal function of organs within the body (e.g., changes in the
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effectiveness of the immune system). Some contaminants are capable of causing both cancer and non-cancer health effects.
Risk Characterization: This step summarizes and combines outputs of the exposure and toxicity assessments to provide a quantitative assessment of site risks. Exposures are evaluated based on the potential risk of developing cancer and the potential for non-cancer health hazards. The likelihood of an individual developing cancer is expressed as a probability. For example, a 10"̂ cancer risk means a "one-in-ten-thousiand excess cancer risk"; or one additional cancer may be seen in a population of 10,000 people as a result of exposure to site contaminants under the conditions explained in the Exposure Assessment. Current Superfund guidelines for acceptable exposures are an individual lifetime excess cancer risk in the range of lO"̂ to 10"̂ (corresponding to a one-in-ten-thousand to a one-in-a-million excess cancer risk) with 10"* being the point of departure. For non-cancer health effects, a hazard index (HI) is calculated. An HI represents the sum of the individual exposure levels compared to their corresponding reference doses. The key concept for a non-cancer HI is that a "threshold level" (measured as an HI of less than 1) exists below which non-cancer health effects are not expected to occur.
The results of the four-step process identified above are summarized in the following paragraphs. The human-health estimates are based on current reasonable maximum exposure scenarios and were developed by taking into account various conservative estimates about the frequency and duration of an individual's exposure to the COCs in the various media that would be representative of site risks, as well as the toxicity of these contaminants.
The Hazard Identification step did not identify any contaminants of concern (i.e., all risks and hazards were within or below acceptable values). The contaminants of potential concern (COPCs) that were identified in the baseline human health risk assessment are summarized in Table 1.
The Exposure Assessment step evaluated the current and reasonably anticipated future land use, the potential receptor populations, and the potential route of exposure. These are summarized in Table 2. The current land use of the Scorpio Recycling facility is industrial/commercial, and it is not expected that the land use will change in the future. The area is served by municipal water and it is not likely that the groundwater underlying the property will be used by individuals for potable purposes in the foreseeable future; however, since the regional groundwater is designated as a drinking water source, hypothetical exposure to groundwater was evaluated.
The results of the Toxicity Assessment step are presented in Tables 3 and 4. The non-cancer toxicity data and the carcinogenic toxicity data were used in conjunction with the results of the previous two steps to complete the Risk Characterization step. The results of the Risk Characterization step indicate that the cancer risk from exposure to groundwater through ingestion, inhalation, or dermal contact were within or below the EPA acceptable risk range. (Table 5). The non-cancer hazard from exposure to groundwater through ingestion, inhalation, and dermal contact were below the acceptable EPA HI of I for all receptor populations with the exception on a hypothetical on-site child resident, which had an HI of 2.0 (Table 6). This exposure scenario is unlikely since the site is an active recycling facility in an industrial area. The Hazard Quotient (HQ) for chromium of 1.5 is the reason for the HI
500016 •12-
being greater than one. Using Central Tendency Exposure (CTE) assumptions, which reflect an average exposure, results in the HI for children to decrease to unity (i.e., 1), and the HQ for chromium also decreases below 1. This suggests that non-carcinogenic hazards would not likely occur for any of the populations present on the site, including on-site residential children.
Uncertainties: The procedures and inputs used to assess risks in this evaluation, as in all such assessments, are subject to a wide variety of uncertainties. In general, the main sources of uncertainty include:
• environmental chemistry sampling and analysis • environmental parameter measurement • fate and transport modeling • exposure parameter estimation • toxicological data
Uncertainty in environmental sampling arises in part from the potentially uneven distribution of chemicals in the media sampled. Consequently, there is uncertainty as to the actual levels present. Environmental chemistry-analysis error can stem from several sources, including the errors inherent in the analytical methods and characteristics of the matrix being sampled.
Fate and transport modeling is also associated with a certain level of uncertainty. Factors such as the concentrations in the primary medium, rates of transport, ease of transport, and environmental fate all contribute to the inherent uncertainty in fate and transport modeling.
Uncertainties in the exposure assessment are related to estimates of how often an individual would actually come in contact with the chemicals of concern, the period of time over Which such exposure would occur, and in the models used to estimate: the concentrations of the chemicals of concern at the point of exposure.
Uncertainties in toxicological data occur in extrapolating both from animals to humans and from high to low doses of exposure, as well as from the difficulties in assessing the toxicity of a mixture of chemicals. These uncertainties are addressed by making conservative assumptions concerning risk and exposure parameters throughout the assessment. As a result, the baseline human health risk assessment provides upper-bound estimates of the risks to populations near the Site, and is highly unlikely to underestimate actual risks related to the Site.
Baseline Human Health Risk Assessment Summary
The BHHRA conducted for the Site estimated carcinogenic risks and non-carcinogenic health hazards for both future Site workers and future Site residential populations (adult and child) potentially exposed to groundwater. Ingestion of and dermal contact with groundwater and inhalation of vaporized groundwater during showering and bathing were evaluated, and cumulative risks were characterized for the Site. Risk analyses indicate that the groundwater at the Site and off the Site does not pose unacceptable carcinogenic risks or non-carcinogenic health hazards for future Site workers and future Site residential adults and children.
5 0 0 0 1 7
• 1 3 -
•
This conclusion is also supported by results reported in the RI and those from past sampling activities. The groundwater beneath and downgradient of the Site has not been found to contain contamination that is above screening level concentrations;
Ecological Investigation
An ecological characterization of the Site was conducted in October 2002 to characterize existing Site conditions relative to the vegetative community structure, wildlife utilization, and sensitive ecological resources. The ecological assessment consisted of the characterization of wildlife habitat/usage and identification of endangered species of concern.
The list of threatened and endangered species in Puerto Rico obtained from both the Puerto Rico and Federal list were evaluated. None of the species listed were observed at and in the vicinity of the S ite during the ecological reconnaiss£mce.
Most of the Site consists of buildings and scrap metal piles; vegetation was only present at the southeastern portion of the Site. There are no surface water bodies on the Site or in the vicinity of the Site. Thus, no potential exposure pathways exist to expose ecological receptors to groundwater. In accordance with EPA's guidance (1997 and 1998), an ecological risk assessment is warranted if there are complete exposure pathways. For the Site, no complete exposure pathways were identified; thus, fiirther ecological evaluation is not warranted.
SUMMARY OF THE SELECTED NO ACTION REMEDY
Based upon the review of all available data and the findings of the RI conducted at the Site, the No Action decision for groundwater is protective of human health and the environment. The Baseline Human Health Risk Assessment indicates that the levels of contaminants present in the groundwater at the Site fall within the acceptable risk range and do not present an unacceptable risk. EPA's extensive removal action at the Site removed large quantities of contaminated soils which represented a potential source of groundwater contamination. Additional potential contaminant sources exist on the Site which, under future changed land use conditions, may present future exposures. Therefore, EPA will perform a Remedial Investigation and Feasibility Study for Operable Unit 2 (Soils) to address contaminant sources at the Site.
DOCUMENTATION OF SIGNIFICANT CHANGES
There are no significant changes from the preferred remedy presented in the Proposed Plan.
5 0 0 0 1 8
• 1 4 -
APPENDIX I Administrative Record Index
5 0 0 0 1 9
• 1 5 -
SCORPIO RECYCLING, INC. SITE ADMINISTRATIVE RECORD FILE
INDEX OF DOCUMENTS
1.0 SITE IDENTIFICATION
1.2 Notification/Site Inspection Reports
P. 100001 - Report: Site Inspection Narrative Report, Scorpio 100381 Recycling, Inc., State Road #2 KM. 19.7,
Candelaria Ward, Toa Baja, Puerto Rico, TDD 02-9312-08, prepared by Puerto Rico Environmental Quality Board, Superfund Program, PA/SI Section, August 23, 1994,
2.0 REMOVAL RESPONSE
2.7 Correspondence
P. 200001 - U.S. EPA Pollution Report, POLREP NO. One (1), 200005 Scorpio Recycling, Inc., prepared by Mr. Adalberto
Bosque, OSC, Air & Hazardous Substances Staff, Caribbean Field Office & Response & Prevention Branch, U.S. EPA, September 30, 1991.
3.0 REMEDIAL INVESTIGATION
3.3 Work Plans
p. 300001 - Report: Final Work Plan, Volume I, Scorpio
300146 Recycling Inc., Remedial Investigation/Feasibility Study, Toa Baja, Puerto Rico, prepared by CDM Federal Programs Corporation, prepared for U.S. EPA, Region 2, October 29, 2001.
P. 300147 - Report: Final Quality Assurance Project Plan, 300546 Scorpio Recycling Incorporated Superfund Site,
Remedial Investigation/Feasibility Study, Toa Baja, Puerto Rico, prepared by CDM Federal Programs Corporation, prepared for U.S.' EPA, Region 2, July 12, 2002.
P. 300547 - Report: Quality Assurance Project Plan, Addendum 300686 No. 1, Scorpio Recycling Inc. Superfund Site,
500020
Remedial Investigation/Feasibility Study, Toa Baja, Puerto Rico, prepared by CDM Federal Programs Corporation, prepared for U.S. EPA, Region 2, September 7, 2004.
3.4 Remedial Investigation Reports
P. 300687 - Report: Technical Memorandum, Monitoring Well 300716 Status, Scorpio Recycling Inc. Superfund Site, Toa
Baja, Puerto Rico, prepared by CDM Federal Programs Corporation, prepared for U.S. EPA, Region 2, March 12, 2003.
300717 - Report: Final Remedial Investigation Report 301198 Operable Unit 1 Groundwater, Scorpio Recycling
Inc. Superfund Site, Remedial Investigation/ Feasibility Study, Toa Baja, Puerto Rico, prepared by CDM Federal Programs Corporation, prepared for U.S. EPA, Region 2, July 21, 2006.
P. 301199 - Report: Final Baseline Human Health Risk 301331 Assessment, Scorpio Recycling Inc. Superfund Site,
Remedial Investigation/Feasibility Study, Toa Baja, Puerto Rico, prepared by CDM Federal Programs Corporation, prepared for U.S. EPA, Region 2, July 25, 2006.
3.5 Correspondence
P. 301332 - Letter to Mr. Adalberto Bosque, Remedial Project 3 01332 Manager, U.S. EPA, Region 2, Caribbean
Environmental Protection Division (CEPD), from Mr. Juan Jose Baba Peebles, Environmental Emergencies Response Manager, Commonwealth of Puerto Rico, Office of the Governor, Environmental Quality Board, re: RI Report Scorpio Recycling Co. Inc., Superfund Site in Toa Baja, PR, July 31, 2006.
P. 301333 - Letter to Mr. Adalberto Bosque, Remedial Project 3 01333 Manager, U.S.. EPA, Region 2, Caribbean
Environmental Protection Division (CEPD), from Mr. Juan Jose Baba Peebles, Environmental Emergencies Response Manager, Commonwealth of Puerto Rico, Office of the Governor, Environmental Quality Board, re: Baseline Human Health Risk Assessment (HHRA), Scorpio Recycling Co. Inc., Superfund Site in Toa Baja, PR, July 31, 2006.
500021
7.0 ENFORCEMENT
7.7 Notice Letters and Responses - 104e's
P. 700001 - Letter to Mr. Jose V. Lanza, President, Scorpio 700003 Recycling, Inc., from Mr. Richard L. Caspe,
Director, Emergency and Remedial Response Division, U.S. EPA, Region 2, re: Scorpio Recycling, Inc. Site, Toa Baja, Puerto Rico; Notice of Potential Liability Pursuant to Comprehensive'Environmental Response, Compensation, and Liability Act, March 7, 1997.
P. 700004 - Letter to Mr. Richard L. Caspe, Director, 700005 Emergency and Remedial Response Division, U.S.
EPA, Region 2, .from Mr. Pedro A. Maldonado-Ojeda, Cancio, Nadal, Rivera, Diaz & Berrios, re: Scorpio Recycling, Inc., Request for Extension of Time to Submit Request for Information Pursuant to Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. §9601, et seq., December 2, 1998.
P. 700006 - Letter to Mr. Ramon Torres, Remedial Project 700006 Manager, Caribbean Environmental Protection
Division, U.S. EPA, Region 2, from Ms. Martha Rivera Rosa, Director, Technical Assistance, Autoridad de Acueductos y Alcantarillados, re: Scorpio Recycling Superfund Site, Vega Baja, February 3, 2005.
P. 700007 - Letter (with enclosures) to Ms. Jean H. Regna, 700162 Esq., Assistant Regional Counsel, Office of the
Regional Counsel, U.S. EPA, Region 2,. from Mr. Francisco Santiago Rodriguez, Senior Attorney, Environmental Law Office, Puerto Rico Electric Power Authority, re: Request for,Information, Scorpio Recycling Superfund Site, Toa Baja, Puerto Rico, February 16, 2 005.
P. 700163 - Letter (with enclosures) to Mr. Ramon Torres, 700198 Remedial Project Manager, Caribbean Environmental
Protection Division, U.S. EPA, Region 2, from Ms. Martha Rivera Rosa, Director, Technical Assistance, Autoridad de Acueductos y
3
500022
Alcantarillados, re: Request for Information pursuant to 42 USC 9604 (e), regarding Scorpio Recycling Superfund, Toa Baja, Puerto Rico, February 2 8, 2 005.
700199 - Letter (with enclosures) to Ms. Jean H. Regna, 700544 Assistant Regional Counsel, New York/Caribbean
Superfund Branch, Office of Regional Counsel, U.S. EPA, Region 2, and Mr. Ramon Torres, Remedial Project Manager, Caribbean Environmental Protection Division, U.S. EPA, Region 2, from Ms. Cristina Lambert, President and CEO, Puerto Rico Telephone, re: Request for Information Pursuant to 42 U.S.C. §9604 (e), regarding Scorpio Recycling Superfund Site, Toa Baja, Puerto Rico, March 10, 2005.
8.0 HEALTH ASSESSMENTS
8.1 ATSDR Health Assessments
P. 800001 - Report: Public Health Assessment for,Scorpio 800057 Recycling, Incorporated, Candelaria Ward, Toa Baja
Municipality, Puerto Rico, EPA Facility ID: PRD987376662, prepared by. Superfund Site Assessment Branch, Division of Health Assessment and Consultation, Agency for Toxic Substances and Disease Registry, prepared for U.S. EPA, June.15, 2004.
See Also: Administrative Record, Scorpio Recycling, Inc.,Road PR No. 2, Km. 19.7, Candelaria Ward, Toa Baja, Puerto Rico, prepared for U.S. EPA, Region II, Enforcement and Superfund Branch, Caribbean Environmental Protection Division, San Juan, Puerto Rico, prepared by Region II Removal Support Team, Weston Solutions, Inc./Scientific & Environmental Associates Inc. Federal Programs Division, Carolina, Puerto Rico, September 2002.
10.0 PUBLIC PARTICIPATION
1Q.2 Community Relations Plans
P. 10.00001- Report: Community Involvement Plan, Scorpio 10.00040 Recycling Inc. Superfund Site, Toa Baja, Puierto
Rico, prepared by CDM Federal Programs Corporation, prepared for U.S. EPA, Region 2, July
500023
26, 2006.
10.9 Proposed Pleui
P. 10.00041- Letter to Mr. Adalberto Bosque, Remedial Project 10.00041 Manager, Enforcement and Superfund Branch, U.S.
EPA, Region 2, from Mr. Juan Jose Baba Peebles, Environmental Emergencies Response Manager, Commonwealth of Puerto Rico, Office of the Governor, Environmental Quality Board, re: Proposed Plan OU-1 (Groundwater) Scorpio Recycling Inc. Superfund Site Toa Baja, Puerto Rico, July 19, 2006.
500024
. . o e n v ' ^ r n S o u a n t V Board's P" - ' * " " " " concurrence Ue«er
• 1 6 ^
500025
2006c 2:42PWEALTH OF PUERTO RIGO **"• * " ^ ^ - " ^
Office of the Governor Environmental Quality Board
^{5*7^** *fTf^^*' '*"i '^h^^^KMftmw!. Envtrontnantal EmergenoB* R»»pon»e Area
Septembei 25,2006
Adalbeito Bosque Remedial Ptoject Manager Enfoicetnent asd Supeifund Bnuidi US Eoviicmmental Ptotection Agency Ceatto Euiopa Building, Suite 417 San Juan, Puctio Rico 00907-4127
RE: RECORD OF DECISION, (ROD) SCORPIO RECYCLING INC. SITE, (SRI) OPERABLE UNIT -1 (GROUNDWATER) TOA BAJA, PUERTO RICO
Deal MI. Bosque:
The Pueito Rico Enrironmental Quality Boatd, (PREQB) teceived die above tefeienced docusient fot evaluatios and conunenta. The purpose of the Record of Decision (ROD) is to document the seleacd remedial action. The SRI sekcti^d temedf addresses the fate and ttanqiott of contaminants in the gtoundwatet emanatiag &om the Site. The No Action selected lemedf va$ chosen in accordance vrith the requirements of 'die Con^iebensire Esviiotunental Response, Compensation and liability Act of 19S0 ("CERCLA") as amended, and die National Oil and Hazardous Substances PoBution Contingency ?kn ("NCP^, in consultation Widi die United States Environmental Ptotcctioo Agency (USEP^. Based iipon the review of all available data and the findings of the Remedial Investigation (RI) conducted at the Site, 'dait No Action decision for groundwater is protective of human health and the environment Therefore, after evaluating the ROD, all available data, asd the findings of the RI, the Puerto Rico Environmental Quality Board (PREQB) concurs with the selected remedial action fot Scorpio Recycling Inc. Site (SRI) Operable Unit - I (groundwater).
If you have any question^ please do not hesitate to contact Ms. Amarilis Rodriguez Mfadet, State Remedial Ptoject Manager at (787) 767-8181 extension 3213 or Mrs. Enid Vjll^as Hendquez, SuperAind Program Remedial Project and Support Chief at extension 3207 oi 3209.
Sincerely,
ianJotei«tal'ee& 'Ennronmental Emergencies Response Manager .
cc Mel Hauptman, USEPA Region 2 Ariel Iglcsias, USEPA Caribbean Field Office
PR - 6638, Sector El Clnco, Ponce de Uibn Ava.lSOe Rio Pledraa, PR OOS07 Tel. 787-767-8161 PO Box 114B8, San Juwi. PR 00910
QTV P.02 SEP-25-2006 14 = 54 ^'^•
500026
APPENDIX III FIGURES
5 0 0 0 2 7
• 1 7 -
A L L N A ^ - ^ " ^ ^ ^
/ »»«»
..-^ ; ^ J « l d ^
S ^ V ^ - ; 7
,»A^ J^.JLW . " , ^Iii,(yjijp--^-' - " •••<-,. „ , / -̂ J « M JS*r i a ddl V >><w -Waria dcJ V •)! . .
Figure 1
SRI Site Location Map
500028
Figure 2
SRI Site Map
500029
West
66'20'30" I
SRI SITE
66"15'
VEQA ALTA QUADRANGLE BAYAMbN QUAORANQLE
East
86'10'30* I
EXPLANATION
NOTE: The Aymamdn Formation is not present
at the SRI Site. The site is underlain by
unconsolidated deposits and the Aguada and Cibao
Formations.
from Troester 1999
linconsolMatad deposits
Camuy Fomiallon
I .ti>^l /^mamAn Fomtatlon
I l I S l Aguada Fdimation
\ u i ^ Upper Member Cibao Fotmation
VSSS Miranda Sand Member Cibao Foimallon
iSg.-:i QuebiBda Arenas Umeslons Member Cibao Fomiation
U'.!.':i!VJ Rio Indio Umeetone Membtr Cibao Fotmation
i 1 Mucarabones Sand
Not to Scale
Figure 3
Schematic Geological Cross Section Across the Vega Alta-Bayamon Area
500030
10'
Pvr*o Salinot
A
eon from \), S. (eole«icgl Sttrvtv n>og. l iSO.000.1942
EXPLANATION
-15
WATER-TASLE CONTOUR
Showt oltitudt of water in voter-table Pmfer , Ciontotjr interval, in feet (metres), j t Mirlbble. Ootuinismean see level.
d 1
1 0
1 1"
1
2 1
1 J
3 MILES 1
4 KILOMETRES
Figure 4
Water Table Contour Map for the Upper Aquifer, Bayamon Area
500031
Figure 5
Monitoring Well Sampling Locations
500032
Figure 6
Supply Well Groundwater Sampling Locations Scorpio Recycling Superfund Site
500033
1 H H V F
sh !̂>
»^ '*Li-k-Ji .
J ^
•"fi-" T % • V
MW-6-R1
»17/2006
SVOCi
bii(2-EVTyinexyt) pMhMate
sc f f t i oam
Pnenot
Met i lB
Altmnnum
Banum
Cadfnum
Caiatjm ufiroftiixjrn Coppei Cranfdo
U a f f i e v u n
Manqanase
4 ««« ^^ ^a^
^
Potassium Sal«rwjm Sodium
Zinc
S J
i..'-:.,;:;i3 J:
; i ^N^^^2 j
' ^" '̂̂ Mr.B J « e . 7 j
0 1 J
C 2 6 J
• 77,-100 •:-5 5 J ' . 7 J •
M J :
• i i * « . 2 0 0 ; ;
' ; '•75to.s J ^ !-K;-6:8 f . 'vi3.6ec J ;
S3 J •i-aa2oe s j^-tfJO-i JJ I
control criteria
N/L Not listed
Note: all results are in uq/l
Round 1 Monitoring Well Sampling Results Remedial Investigation/ Feasibility Study
Scorpio Recycling Sufjerfund Site ^^^^ Toa Baja, Puerto Rico
C O M - J
Figure 7
Round 1 Monitoring Well Sampling Results
500034
J
N/A
N/L
Monitoring Wells
No standard value available for comparison
Estimated data due to exceeded quality control criteria Not applicable as the compound analyzed was not delected in the sample
Not listed
Round 2 Monitoring Well Sampl ing Results
Remedial Investigation/ Feasibil i ty Study
Scorpio Recycl ing Superfund Site
I Feet
Note- sll results ore in uq/L 125 250 500 COM—I
Figure 8
Round 2 Monitoring Wells Sampling Results
500035
Public Supply Wells
No standard value available for comparison
J Estimated data due to exceeded quality control criteria
l^y^ Not applicable as the compound analyzed i:
was not detected in the sample
N/L Not listed
Note: all results are in uqA
approximate sc3le
Offsite Monitor ing Wel l Sampl ing Results Remedia l Invest igat ion/ Feasibil i ty Study
Scorpio Recycl ing Superfund Site Toa Baja, Puerto Rico
UFeel 800 1600
C O M - "
Figure 9
Offsite Monitoring Well Sampling Results
500036
Figure 10
Round 3 Monitoring Well Sampling Results
500037
T he 3 5
I
1^5 1 ^
_ Ci jmpani l la 1 z £ . ^ ^ - -
C£|mpanilla 7
'' ^ ^ ^ ^ K ^
O Public Supply Weils
^ » 1 No Standard value available for comparison
J Estimated data due to exceeded quality control criteria 1^^ Not applicable as the compound analyzed
appra^irratd sea! was not detected in the sample N/L Not listed Note: all results are in ug/L
Round 3 Offsite Monitoring Well Sampling Results A Remedial Investigation/ Feasibiiity Study ' "^ Scorpio Recycling Superfund Site
Toa Baja, Puerto Rico
]Feel
COM
N
J
Figure 11
Round 3 Offsite Monitoring Well Sampling Results
500038
APPENDIX IV TABLES
5 0 0 0 3 9
• 1 8 -
TABLE 1
Page 1
Summary of Chemicals of Concern and Medium-Specific Exposure Point Concentrations
Scenario Timeframe: Current/Future Medium: Groundwater Exposure Medium: Groundwater
Exposure Point
Tap Water
Cliemical of Concern
Trichloroethylene
Chromium
Arsenic
Concentration Detected
Min
0.09
2.1
2.4 •
Max
0.5
89.8
2.4
Concentration Units
Hgfl
Hg/l
|ig/l
Frequency of Detection
2/12
8/12
1/12
Exposure Point Concentration
(EPQ
0.5
56.5
2.4
EPC Units
i^en
iig/i
iig/i
statistical Measure
Max.
95%Cheb
Max
Max - Maximum value detected 95% Cheb = 95% Upper Confidence Limit using Chebyshev (Mean, STD)
500040
- 1 9 -
TABLE 2
Selection of Exposure Pathways
Scenario Timeframe
Medium Exposure Medium .
Exposure Point
Receptor Population
Receptor Age
Exposure Route
Onsite/ Offsite
Rationale for Selection/Exclusion of Exposure Pathway
Current/Future Groundwater Groundwater
Indoor Air
Tap water
Water Vapors in Bathroom
Resident
Resident
Adult
Child (0-6 yr)
Adult
Child (0-6 yr)
ingestion
Dermal
Ingestion
Dermal
Inhalation
Inhalation
Onsite
Onsite
Onsite
Onsite •
Onsite
Onsite
Groundwater in the area used as potable water source by public supply well. Municipal water meets all applicable standards.
Groundwater in the area used as potable water source by public supply well. Municipal water meets all applicable standards. |
Groundwater in the area used as potable water source by public supply well. Municipal water meets all applicable standards.
Groundwater in the area used as potable water source by public supply well. Municipal water meets all applicable standards. |
Groundwater in the area used as potable water source by public supply well. Municipal water meets all applicable standards. |
Groundwater in the area used as potable water source by public supply well. Municipal water meets all applicable standards. |
Summary of Selection of Exposure Pathways
The table describes the exposure pathways associated with the groundwater that were evaluated for the baseline human health risk assessment, and the rationale for the inclusion of each pathway. Exposure media, exposure points, and characteristics of receptor populations are included.
- 2 0 - 500041
TABLES
Non-Cancer Toxicity Data Summary
Pathway: Oral/Dermal
Cliemical of Concern
Trichloroethelyene
Chromium'
Arsenic
Chronic/ Subchronic
Chronic
Chronic
Chronic
Oral RfD
Value
3.0E-4
3.0E-3
3.0E-»
Oral RfD Units
mg/kg-day
mg/ltg-day
mg/lig-day
Absorp. EfTidency (Dermal)
NA
2.5%
NA
Adjusted RfD
(Dermal)
3.0 E-4
7.5 E-5
3.0 E-4
Adj. Dermal
RfD Units
mg/kg-day
mg*g-day
mg*g-day
Primary Target Organ
Liver
01 Tract
Skin
Combined Uncertainty /Modifying
Facton
3000
900
3
Sources of RfD: Target Organ
NCEA
IRIS
IRIS
Dates of RfD:
2006
03/01/06
03/01/06
Pathway: Inhalation
Chemical of Concern
Trichloroethylene
Chromium'
Arsenic
Chronic/ Subchronic
Chronic
Chronic
NA
Inhalation RfC
4.0E-2
8.0E-6
NA
Inhalation RfC Units
mg/cu. m
mg/cu. m
NA
Inhalation RfD
I.IE-2
2.3E-6
NA
Inhalation RfD UniU
mg/kg/day
mg/kg-day
NA
Primary Target Organ
CNS
Nasal septum atrophy
NA
Combined Uncertainty /Modifying
Factors
1000
90
NA
Sources of RfD:
Target Organ
NCEA
IIUS
IRIS
Dates:
2006
03/01/06
07/01/02
' The RfD for hexavalent chromium has been applied to total chromium
Key
NA: No information available IRIS: Integrated Risk Information System, U.S. EPA NCEA: National Center for Environmental Assessment, U.S. EPA
Summary of Toxicity Assessment
This table provides non-carcinogenic risk information which is relevant to the contaminants of concern in groundwater. When available, the chronic toxicity data have been used to develop oral reference doses (RfDs) and inhalation reference doses (RfDi).
•
500042
- 2 1 -
TABLE 4
Cancer Toxicity Data Summary
Pathway: Oral/Dermal
Chemical of Concern
Trichloroethylene
Chromium'
Arsenic
Oral Cancer Slope Factor
4.0E-1
NA
1.5E-H0
Unite
(mg/kg/day)-'
(mg/kg/day)-'
Adjusted Cancer Slope
Factor (for Dermal)
4.0E-1
NA
1.5E-K)
Slope Factor Unite
(mg/kg/day)-'
(mg/kg/day)-'
Weight of Evidence/
Cancer Guideline
Description
Bl
D
A
Source
NCEA
IRIS
IRIS
Date
2006
07/01/02
03/01/06
Pathway: Inhalation
Chemical of Concern
Trichloroethylene
Chromium'
Arsenic
Unit Risk
NA
1.2E-2
4.3E-3
Unite
NA
mg/cu. m.
mg/cu. m
Inhalation Slope Factor
4.0E-1
4.2E+1
1.5E-H
Slope Factor Unite
mg/kg-day
mg/kg-day
mg/kg-day
Weight of Evidence/ Cancer Guideline
Description
Bl
A
A
Source
NCEA
IRIS
IRIS
Date
2006
03/01/06
03/01/06
' Chromium VI is an A carcinogen by the inhalation route, but D carcinogen by the oral route. The CSF for hexavalent chromiimi has been applied to total chromium.
Key EPA Group:
NA: No information available A - Human carcinogen IRIS: Integrated Risk Information System, U.S. EPA Bl - Probable Human Carcinogen - Indicates limited evidence in NCEA - National Center for Environmental Assessment, U.S. EPA humans
D - Not classifiable as a human carcinogen
Summary of Toxicity Assessment
-phis table provides carcinogenic risk information which is relevant to the contaminants of concern in groundwater. Toxicity data are provided for both the oral and inhalation routes of exposure.
500043
•22 -
1 TABLES Page 1
Risk Characterization Summary -- Carcinogens Scenario Timeframe: Current/Future Receptor Population: Resident Receptor Age: Adult
Medium
Groundwater
Exposure Medium
Groundwater
•
Exposure Point
Tap Water
1 Chemical of Concern
Trichloroethylene Chromium Arsenic
1 Carcinogenic Risk Ingestion
1.9E-06
3.4E-05
Inhalation
7.2E-06 —
NA
Dermal
5.1E-08 —
2.0E-07 Total Risk =
Scenario Timeframe: Current/Ful Receptor Population: Resident Receptor Age: Child (0-6 ]
Medium
Groundwater
Exposure Medium
Groundwater
Exposure Route Total
9.1 E-6 1
3.4E-05 4.0E-05
ture 1
Exposure Point
Tap Water
Chemical of Concern
Trichloroethylene Chromium
Arsenic
Carcinogenic Risk | Ingestion
1.1E-06
2.0E-05
Inhalation
1.6E-05
NA
Dermal
3.9E-08
5.9E-08 TotarRisk= 1
Exposure 1 Route Total
1.7E-05
2.0E-05 4.0E-05 1
Summary of Risk Characterization - Carcinogens
The table presents cancer risk (CRs) for each route of exposure and for all routes of exposure combined. The Risk Assessment Guidance for Superfund states that, generally, the acceptable cancer risk range is 10"̂ to 10"̂ . |
500044
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1 TABLES Page 1
Risk Characterization Summary - Noncarcinogens Scenario Timeframe: Current/Future Receptor Population: Resident Receptor Age: Adult
Medium
Groundwater
Exposure Medium
Groundwater
Exposure Point
Tap Water
Chemical of Concern
Trichloroethylene Chromium Arsenic
Primary Target Organ
Liver Gl Tract
Skin
Noncarcinogenic Risk I Ingestion
0.046 0.5
0;22 1 Groundwater
Inhalation
0.0046
— .
Dermal
0.0012 0.093
0.00049 Hazard Index Total =
Exposure Route Total
0.05 0.61 • 0.22 0.9 1
Scenario Timeframe: Current/Future 1 Receptor Population: Resident Receptor Age: Child (0-6 yr) I
Medium
Groundwater
Exposure Medium
Groundwater
Exposure Point
Tap Water
Chemical of Concern
Trichloroethylene Chromium
Arsenic
Primary Target Organ
Liver Gl Tract
Skin
Noncarcinogenic Risk | Ingestion
0.1 1.2 0.5
Groundwater
Inhalation
0.04
Dermal
0.004 0.29
0.0015 Hazard Index Total =
Exposure 1 Route Total
0.15 1.5 0.5 2 1
Summary of Risk Characterization - Noncarcinogens 1
The table presents hazard quotients (HQs) for each route of exposure and the hazard index (sum of hazard quotients) for all routes of exposure. The Risk Assessment Guidance for Superfund states that, generally, a hazard index of (HI) greater than
1 indicates the potential for adverse non-cancer effects. 1
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