United Slates Environmental Protection Agency Office of Emergency and Remedial Response EPA/ROD/R07-87/007 September 1987 Superfund Record of Decision: Minker Stout/Romaine Creek, MO ------- TECHNICAL REPORT DATA (Hem read Instructions on the reverie before completing) 1. REPORT NO. EPA/ROD/R07-87/007 2. 3. RECIPIENT'S ACCESSION NO. >. TITLE ANO SUBTITLE SUPERFUND RECORD OF DECISION Minker/Stout/Romaine Creek - Romaine Creek Portion, MO Second Remedial Action S..REPORT DATE • September 28, 1987 «. PERFORMING ORGANIZATION CODE 7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO. 9. PERFORMING ORGANIZATION NAME ANO ADDRESS 10. PROGRAM ELEMENT NO. 1. CONTRACT/GRANT NO. 12. SPONSORING AGENCY NAME ANO ADDRESS U.S. Environmental Protection Agency 401 M Street, S.W. Washington, D.C. 20460 13. TYPE OF REPORT ANO PERIOD COVERED Final ROD Report 14. SPONSORING AGENCY CODE 800/00 15. SUPPLEMENTARY NOTES The Romaine Creek portion of the Minker/Stout/Romaine Creek site is located in Jefferson County, Missouri,, approximately 20 miles southwest of St., Louis. Romaine Creek starts at the- Minker area, and flows 4.6 miles to its confluence with Saline Creek. Romaine Creek is located in a rural residential area, and is not used for municipal, industrial, or. domestic purposes.. In the late 1960s and early 1970s, a southwest Missouri chemical plant producing-2,4,5-T and.hexachlorophene contracted a waste oil reclaimer to remove process residues.. The residues, contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were mixed with waste oils and sprayed as a dust suppressant on a nearby horse arena. In March of 1973, the owner of the horse arena had the contaminated soils removed to various portions of the Minker/Stout/Romaine Creek site. Approximately 120 yd-* of this soil was used as fill in a ravine on the Minker property, and since 1973, much has eroded into Romaine Creek. In 1982, contaminated soils above 1 ug/kg TCDD were excavated from the Minker portion of the site. The primary contaminant of concern is dioxin. The selected interim remedial measure for the Romaine Creek portion of this site includes: excavation and temporary onsite storage of soils and sediments contaminated with greater than 1 ug/kg TCDD; and backfilling of the excavated areas with clean material suitable for the establishment of a natural stream bed. The estimated present worth cost for this remedial action is $4,488,000 with annual O&M of $28,000. 7. - KEY WORDS ANO DOCUMENT ANALYSIS DESCRIPTORS b.lOENTIPIERS/OPEN ENDED TERMS C. COSATI Field/Group Record of Decision Minker/Stout/Romaine - Romaine Creek Portion, MO Second Remedial Action Contaminated Media: soil, sediment Key contaminants: dioxin 8. DISTRIBUTION STATEMENT 19. SECURITY CLASS (This Report) None 21. NO. OF PAGES 19 20. SECURITY CLASS fTlliS pagei None 22. PRICE EPA Form 2220-1 (R*v. 4-77) PMKVIOUS COITION i* O»*OLCTC ------- Record of Decision OperaDle Unit Remedial Alternative Selection SITE: Romaine Creek Portion of Minker/Stout/Romaine Creek NHL Site DOCUMENTS REVIEWED I am basing my decision primarily on the following documents describing the analysis of cost-effectiveness of operable unit remedial alternatives for interim management of dioxin-contaminated materials at the Komaine Creek portion of the Minker/Stout/Romaine Creek NPL site. Additional documents considered are included in the Administrative Record for this action. - Operable Unit Feasibility Study - Komaine Creek Portion of the Minker/Stout/Romaine Creek Site. - Summary of Remedial Alternative Selection - Romaine Creek Portion of the Minker/Stout/Romaine Creek Site. - Responsiveness Summary - Operable Unit Remedial Actions for the Stout and Romaine Creek Portions of the Minker/Stout/Romaine Creek Site. - Federal Position Statement on Dioxin in Missouri, Centers for Disease Control, December 7, 1982. - Public Health Advisory, for the Minker/Stout Sitas, Centers for Disease Control, March 17, 1983. - Addendum to'March 17 "Public Health Advisory for the Minker/Stout Sites," • Centers for Disease Control, April 7, 1983. - Health Implications of 2,3,7,8-tetrachlorodibenzodioxin (TCDD) Contamination of Residential Soil, Kimbrough, R.D., et al., Journal of Toxicity and Environmental Health, 14:47-93, 1984. - Memorandum, Review of Analysis Data for 2,3,7,8-TCDD in Romaine Green Sediment and Biota, Jefferson County, Missouri, Stephen Margolis, Ph.D., to Edward J. Skowronski, Agency for Toxic Substances and Disease Registry, March 1U, 1986. DESCRIPTION OF SELECTED REMEDY The selected operable unit remedial action alternative involves the excavation of soil and sediment in Romaine Creek contaminated with 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCUD) at levels exceeding one part per billion (1 ppb). Contaminated materials will be excavated until a residual TCDD concentration of less than 1 ppb remains. Excavation will not continue beyond a depth of four feet, or once solid bedrock is encountered. Excavated materials will be containerized and placed in temporary onsite storage until a final management alternative is implemented. Storage structures for the excavated material will be constructed on the former Edwards property adjacent to ------- Romaine Creek. These storage structures will be designed and constructed in accordance with the substantive requirements for hazardous waste storage fact 11 ties under the Resource Conservation and Recovery Act, as amended. Following removal of contaminated material from Romaine Creek, excavated areas will oe backfilled with clean material suitable for the establishment of ci natural streambed. DECLARATIONS Consistent with the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended, and the National Contingency Plan (40 CFR Part 300), I have determined that excavation and interim onsite storage of TCDD-contaminated materials at the Romaine Creek portion of the Minker/Stout/Romaine Creek site is cost-effective, consistent with a perttanent remedy, and provides adequate protection of public health, welfare, and the environment. The remedy selection procedure and selected alternative comply with provisions of the Superfund Amendments and Reauthorization Act of 1986. The State of Missouri has been consulted and concurs with the selected remedy. I have also determined that the action being taken is appropriate when balanced against the availability of Trust Fund monies for use at other sites. The selected operable unit remedial alternative is consistent with Section 300.68(c) of the National Contingency Plan, and is a component of a total remedial action which will attain all applicable or relevant and appropriate requirements for. the protection of public health and environment. Date p Regiorfal Administrator / ------- SUMMARY OF REMEDIAL ALTERNATIVE SELECTION ROMAINE CREEK PORTION OF THE MINKER/STOUT/ROMAINE CREEK SITE JEFFERSON COUNTY. MISSOURI The purpose of this document is to state the interim remedy that the Agency has selected to implement at Romaine Creek. This document will also include a brief analysis of remedial action alternatives which have been evaluated leading to the Agency's decision of remedy preference. An operable unit is defined as a discrete part of an entire response action for an uncontrolled hazardous waste site which functions to decrease a release, threat of release, or pathway of exposure of site hazardous substances. Operable units must be consistent with the final remedy for a site and must be cost-effective according to the provisions of SARA. It is assumed in this document that the final remedial action for the Romaine Creek operable unit will involve offsite management, which will require eventual excavation of contaminated soil and sediments. SITE DESCRIPTION The Romaine Creek portion of the Minker/Stout/Romaine Creek hazardous waste site is located in Jefferson County, Missouri, approximately 20 miles southwest of St. Louis. Romaine Creek starts at the Minker area and flows 4.6 miles to its confluence with Saline Creek. Saline Creek empties into the Meramec River 0.2 miles downstream. Romaine Creek is located in a rural residential area. There are no businesses or industries located in the watershed, and the water is not used for municipal or industrial purposes. There are some private wells in the area, but most residential water is indirectly supplied from St. Louis County Water Company. Due to its small size, and intermittent flow in the upper reaches, the creek is not used for domestic water supply. The first mile of the creek has a moderate channel gradient and steep slide slopes, and the remainder of the creek has a moderate to low gradient and flatter side slopes. Approximately the upper half of the creek is dry much of the year. SITE HISTORY The Minker/Stout/Romaine Creek site was placed on the Environmental Protection Agency's (EPA) National Priorities List (NPL) of uncontrolled hazardous waste sites in 1983 because 2,3,7,a tetrachlorodibenzo-p-dioxin (TCDD) was detected in the soil. A historical investigation of the situ- ation indicated the contaminants originated from a chemical plant in southwest Missouri, which produced nexachlorophene and 2,4,5-T in the late 1960's and early 1970's. • ------- In 1971, a Missouri waste oil reclaimer was contracted to remove process residues contaminated with TCDO from a tank located at the southwest Missouri plant. This material was subsequently mixed with waste oils and sprayed as a dust: suppressant on the Bubbling Springs Horse Arena near Imperial, Missouri. In March of 1973, the horse arena owner contracted with a local hauler for the removal of the contaminated soil from the arena. The arena was excavated and material was deposited at the various portions of the Minxer/Stout/Romaine Creek site. Approximately 120 cubic yards of this excavated soil were placed as fill in a ravine at the Minker property. Since 1973, a significant quantity of the MinKer fill has eroded into Romaine Creek. Sampling for TCDO The EPtt Initially sampled and analyzed Romaine Creek sediments for TCOD in 1982. Approximately 150 samples were collected from the Minker area to near the mouth of the creek. At a detection limit of approximately 1 ppb, TCDL) was not detected beyond b.OOO feet downstream of the Minker area. Concentrations ranged from a maximum of 272 ppb near the Minker area to less tnan 1 ppb 7,400 feet downstream. In 1985, biota and additional sediment samples were collected and analyzed by the EPA. Twelve sediment samples were collected, approximately one sample every half mile. TCDO was detected 1/2 mile downstream of the M1 nicer area at concentrations as high as 36.3 ppb. (Tn-is was the closest sample to the Minker area.) The next sampling location which was 1-mile downstream of'the Minker area, and all sample locations farther downstream had average TCDD concentrations of less than 1 ppb. (Detection limits were generally in the range of 0.10 to 0.20 ppb.) The sampling location farthest from the Minker area, 4.5 miles downstream, had an average TCDD concentration of 0.3 ppb; this indicates that a small amount of TCDD may be eroding to the mouth of the creek. The 1985 biota sampling was conducted to determine if aquatic organisms in Romaine Creek and in Saline Creek below the Romaine Creek confluence had bioconcentrated TCDD. TCDD was detected in all the aquatic species sampled (fish, crayfish, amphipods). TCDD concentration was typically greater than 50 parts per trillion (ppt). Above Bubbling Springs, Romaine Creek 1s an intermittent stream and does not have sufficient aquatic habitat to support fish and crayfish. Cleanup activity to date has included excavation of soils exceeding 1 ppb TCDD at: the Minker area in 1986, which is the source of cne Romaine Creek contamination. Warning signs have been posted along the contaminated portion of Romaine Creek. A state-issued fishing advisory is in effect for the Meramec River due to elevated levels of chlordane detected in fish samples collected from the river. COMMUNITY RELATIONS HISTORY Section 117 of SARA provides that notice must be published and a brief • analysis of the proposed plan be made available to the public. A reasonable ------- opportunity for submission of oral and written comments must be provided. The opportunity for a public meeting near the site is required regarding the proposed plan. Any findings concerning compliance with federal and state cleanup standards must be provided to the public. A public comment period was held for the Romaine Creek Operable Unit Feasibility Study (UUFS) and Proposed Plan from August 20 through September 21, 1987. A public meeting was conducted September 10, 1987, to discuss these documents and the Agency's tentatively selected alternative. All documents released were made available for public inspection and copying at EPA Public Information Centers located on Lewis Road, immediately east of Times Beach, and at the intersection of Kiefer Creek Road and Ries Road in Castlewood (Ballwin), Missouri. These EPA information facilities provided the opportunity for public access to information six days a week. An onsite EPA public information center will be established and remain open during implementation of any remedial action at Romaine Creek. The opportunity for public participation has been provided prior to and during all dioxin cleanup activities in Missouri since EPA began actively investigating potential Missouri dioxin sites in 1982. Cleanup activities to date have consisted of removal actions taken to reduce exposure to dioxin-contaminated soils by containment and by excavation and secure storage. Public meetings have been conducted prior to all removal activities implemented since 1984 to solicit public comments so that the Agency could be aware of and responsive to the public's concerns. •Cleanup measures being addressed in this document represent interim actions for the management of dioxin-contaminated sediments prior to final management. Final management of dioxin-contaminaced materials is being addressed separately, and was evaluated in the Feasibility Study of Final Remedial Actions for the Minker/Stout/Romaine Creek site. A public comment period was held for the Feasibility Study of Final Remedial Actions for the Minker/Stout/Romaine Creek Site from August 8, 1986, until September 5, 1986. A public meeting was held on August 25, 1986, at a local public facility in order to discuss the alternatives evaluated in the study and the Agency's proposed remedy. At the public meeting it was announced that the only alternative in the study which the Agency currently considered feasible to implement for final management of contaminated soils was offsite thermal treatment within 50 miles of the site. It was also announced that the State of Missouri had recommended and suggested the evaluation of Times Beach as a location for offsite thermal treatment, and that EPA was evaluating Times Beach as a possible location for siting a mobile thermal destruction unit. It was announced that a feasibility study to evaluate Times Beach as a potential location for offsite thermal treatment would be completed and released for public comment in January 1987. ALTERNATIVES EVALUATION SITE OBJECTIVES General site-specific objectives are 1) to prevent or reduce long-term human contact with soils containing dioxin at concentrations exceeding ------- the action level whicn is determined to be protective of public health and 2) to minimize the potential for offsite migration of dioxin. Operable unit alternatives must be consistent with the final remedial action. An objective of all alternatives involving treatment is to achieve destruction and removal efficiencies (DKE's) which meet applicable or relevant and appropriate regulatory criteria. The Romaine Creek Operable Unit Feasibility Study evaluates removal of soil dnd sediment exceeding an action level or target cleanup level of 1 ppb. Federal and state health officials have determined that 1 ppb in a residential area is a reasonable level at whicn to express concerns about public health risks. Complete removal of all contaminated soil and sediment was also evaluated. INSCRIPTION OF ALTERNATIVES A brief description of the operable unit alternatives is given in this section. Five alternatives have been given consideration for the interim remedy for Komaine Creek. Additional development, description, and evaluation of each alternative is presented in the Romaine Creek Operable Unit Feasibility Study. Alternative 1: No Action Under the no-action alternative, no additional remedial action-s. would be taken at Romaine Creek. Alternative 2: Limited Action Limited action would involve implementation of site-use restrictions, as deemed .necessary and posting of warning signs along the full length of the creek, plus fencing at road crossings to limit public access. The alternative would also Include annual monitoring of TCDD distribution within Romaine Creek and monitoring for TCDD in nearby selected wells. Alternative 3: Stabilization This alternative would include the same scope items as described for Alternative 2 plus the additional measures of quarterly monitoring and 1n-place stabilization of the sediments contaminated at levels greater than 1 ppb. Stabilization would be accomplished using vegetation and manufactured erosion control mats. As- previously described, the reach of creek contaminated at levels exceeding 1 ppb lies within that portion which is dry much of the year. Alternative 4: Excavation to 1 ppb and Storage Alternative 4 would involve excavation and temporary onslte storage of all soils and sediments contaminated at concentrations exceeding 1 ppb, ------- and implementation of a monitoring program similar to Alternative 2. It is estimated that approximately 4,400 cubic yards of contaminated material would be removed and stored during implementation of this alternative. It is assumed that the excavated sediments would be stored in semi bulk sacks placed in metal buildings, as has been aone by the EPA during removal actions performed at other Missouri dioxin sites. A storage site was not selected; however, it was assumed that the site would be adjacent to the creek, protected from a lUO-year flood, and that it would be relatively flat. Alternative b: Complete Excavation and Storage Alternative 5 would involve excavation and temporary onsite storage of all sediments within Romaine Creek. A preliminary estimate made of the sediment volume that would be stored during implementation of this alternative is so,000 cubic yards. Storage would be as described for Alternative 4. EVALUATION OF ALTERNATIVES The five operable unit alternatives considered in the detailed evaluation were compared to CERClA criteria for the selection of remedy. These remedy selection criteria include the following: 0 Compliance with ARARs 9 Reduction of mobility, toxicity, or volume of • waste 0 Short-term effectiveness o Long-term effectiveness 0 Permanence 0 Implementability 0 Cost 0 Community and state acceptance Table I presents an evaluation of eacn alternative against these evaluation criteria. A discussion of each criteria and their attainment by each of the alternatives follows: Compliance with ARARs Section 121(d) of CERCLA, as amended by SARA, requires that remedial actions comply with requirements or standards under federal and state laws for the protection of public health and the environment. Section 121(d) allows a remedy to be selected that does not attain a level of control at ------- TABLE 1. REMEDY SELECTION CRITERIA • ROMAINE CREEK ALTERNATIVE COMPLIANCE WITH ARARs REDUCTION OF MOBILITY, TOXICITY, OR VOLUME OF WASTE SHORT-TERM EFFECTIVENESS LONG-TERM EFFECTIVENESS (Consistent with (complete remedy which (complies with ARARS. 1: No Action (No reduction of (Risks to public health (mobility, toxicity, or (and the environment (volume. Some increase (remain at current |in contaminated sediment(levels. |volume requiring future | (excavation may occur due) (to contaminant migra- | (tion. | I I (Existing contaminants [would remain in place (unless migration occurs. (Risks to public health (and the environment (remain at current (levels. Site boundaries (may expand due to (continued migration. (Consistent with (complete remedy which (complies with ARARS. 2: Limited Action (No reduction of (Low potential for (mobility, toxicity, or (exposure to community {volume. Some increase (or environment in excess (in contaminated sediment(of current levels or (volume requiring future (exposure to workers (excavation may occur due(during implementation. (to contaminant migra* (Implementation would (tion. (require less than on* (year. (Monitoring program would (detect contaminant origra- jtion. Fencing would control (access to contaminated por- jtion of stream. Low OIM req- juirements. Protection (achieved immediately upon (completion. (Consistent with (complete remedy which (complies with ARARS. •I- I 3: Stabilization (No reduction in toxic- (Greater potential for (Reduced potential for jity. Volume of material (exposure to workers and (exposure to community and (requiring eventual sxca-|community relative to (environment. Existing cor |vation will increase duejalt. 2 due.ro soil dfst-jaminants remain in place |to volume of stabilizat-jurbance. Disturbance of (High Q&H requirements to (ion material. Mobility (wildlife ana increased (maintain vegetation. Reliab- (would be reduced and (stream turbidity BOSS- jility of vegetative cover (could be controlled withfible. Could be completed(uncertain. Vegetation may be (adequate maintenance. (within 2 years. (difficult to establish. (Consistent with i (complete remedy which (complies with ARARS. I 4: Partial Excavation (Storage structures (No reduction in toxic- (Increased potential for (ity. Mobility controlled(exposure to workers and (by containerization and (community due to soil (secure storage. Volume (disturbance. Temporary (of contaminated sediment(wildlife disturbance (designed and constructed (fixed at current level, (and increased stream (to RCRA standards. (Estimated 4,400 cy of (turbidity possible. j (material would require (Could be conoleted | (final management. (within 2 years. (Exposure potential reduced (to residential standards. (Stream levels permanently (reduced to less than 1 ppb. (Potential bioaccumulation in (non-fishable stream. Protec |tion achieved immediately (upon completion. Limited 0*M (requirements for structures. (No reduction in toxic- (Increased potential for Iity. Mobility control led(exposure to workers and (by containerization and (community due to soil (secure storage. Volume (disturbance. Temporary (of contaminated sediment(wildlife disturbance (designed and constructed(fixed at current level, (and increased stream (to RCRA standards. (Estimated 50,000 cy of (turbidity possible. I (material would require (Implementation would | (final management. (require 3-4 years. (Consistent with (complete remedy which (complies with ARARS I Complete Excavation (Storage structures (Exposure potential for coma- (unity and environment elim- jinated. No residual contam- |(nation would remain. (Potential bioaccumulation (eliminated. Protection (immediate upon completion. (Limited 0*M requirements (for storage structures. ------- TABLE 1. REMEDY SELECTION CRITERIA - ROMAINE CREEK (cent.) ALTERNATIVE PERMANENCE IMPLEMENTABILITY COST COMMUNITY AND STATE ACCEPTANCE |1: No Action 2: Limited Action 3 iilization (4: Partial Excavation I 5: Complete Excavation (No direct impact (on future management (requirements. (Volume of material (requiring final manage- |merit may increase or (decrease due to contam- jinant migration. ' (No direct impact Jon future management (requirements. (Volume of material (requiring final manage- (ment may increase or (decrease due to ccntam- jinant migration. n/a | (Community desires that (Total present worth: (Romaine Creek be cleaned (up as soon as possible. $0 (State recognizes need to (initiate action. Annual O&M cost: (No action not consistent (with community and state $0 (sentiment. I (Straightforward implem- jentation. Uncertain |reliability due to un- |authorized site intrud- jers. Access to affected (private properties (would be required. (Does not represent perm- janent fixation. Regular Imaintenance would be •I- (Community may interpret Total present worth: (as final action, and (would object to implem- $211,000 jentation from esthetic (standpoint. Limited Annual OSM cost: (Action not consistent (with past state actions. $21,000 j Establishment of veget- ation nay be difficult in some areas. Erosion •(required to maintain, thefmay occur during severe (volume of soil requiring(storms. Access to (final management at (private properties (current level. Increase (would be required. (In total volume due to j (stabilization materials.| (Total present worth: $937,000 Annual. 32M cost: (Permanently reduce (levels in creek to (below 1 ppb. |Containerization (would facilitate (future handling. (Implementation faciI it- fated by proper selection Total (of equipment. Reliabil jity of storage struct- (ures high. Access to (private properties (would be required. I Permanently remove (Removal of submerged (existing contamination (sediments difficult. De- Total (to background levels. (watering necessary. jRecontamination possibleJAccess to many private (from Minker site. (properties required. (Containerization (Reliability of storage (would facilitate (structures high. Insuf- jfuture handling. jficient onsite area for j (required structures. $37,000 (Community may interpret |as final action, and (would object to need [to access.property and (disturb creek twice. (Not consistent (with past state actions. I present worth: $4,488,000 Annual O&M cost: $28,000 I (Community would support (removal of contamination (from creek, but may ob- jject to siting of stor- jage structures. (Consistent with past state actions. present worth: $27,900,000 Annual O&M cost: $22,000 I (Community would support (removal of contamination (from creek, but may ob- jject to siting of stor- jage structures. Large (number of required (structures objectionable. (Consistent with past (state actions. •I ------- least: equivalent to a legally applicable or relevant and appropriate requirement (AKAR) if the remedy selected is only part of a total remedial action that will attain such a level of control when completed. The operable unit alternatives evaluated in the feasibility study represent only part of the-complete remedy for Romaine Creek. It is not necessary for these alternatives to comply with all AKARs. The alternatives will, however, be compared to ARARs and evaluated to determine the extent to which each is consistent with a final remedy which attains ARARs. All alternatives evaluated are consistent with final remedial actions which involve treatment or disposal. A complete remedy involving the treatment or disposal of dioxin-contaminated soils and sediment would potentially meet all ARARs. The operable units evaluated are therefore consistent with complete remedies which meet ARARs. The land ban regulations governing the land disposal of dioxin-contaminated waste:* are expected to go into effect in November 1988. Final management of soils and sediments from Romaine CreeX will not occur before that date. The land ban regulations state that dioxin-contaminated soils can be land disposed if they pass the Toxicity Characteristics Leaching Procedure (TCLP). Based upon existing sample results from Romaine Creek, it is expected that the excavated, sediments would pass the TCLP test and be exempt: from the dioxin land ban. Permits are not required for onsite remedial actions at Superfund sites. Although formal permits are not required, any action must meet the substantive technical requirements of the permit process. Storage structures included in alternatives involving excavation and interim onsite storage of contaminated soils will be designed and constructed in compliance w--n the appropriate substantive requirements of the Resource Conservation and Recovery Act, as amended (RCRA). Reduction of Mobility, Toxicity, or Volume of Waste Section 121(b) of CERCLA, as amended, states that remed-'al actions involving treatment which permanently and significantly reduce the volume, mobility, or toxicity of hazardous materials are to be preferred over those not involving such treatment. This evaluation criteria relates to the ability of a remedial alternative to control or eliminate risks caused by the mobility, toxicity, or volume of a hazardous waste. Alternatives 1 and 2 would have no direct impact on the mobility, toxicity, or volume of hazardous materials in Komaine Creek, however, failure to stabilize or contain dioxin-contaminated sediments may result in expanded site boundaries and an increased soil volume requiring future management. Stabilization of contaminated areas in Romaine Creek would reduce the potential for erosion and transport which currently exists. Implementation of this alternative would result in an increase in the soil volume requiring future management due to the volume of stabilization material. ------- Alternatives involving the excavation and interim onsite storage of contaminated soils would result in decreased potential for migration. Mobility of excavated material would be eliminated due to containerization and secure storage. Migration of contamination not removed from the creek could continue to occur. Excavation of sediments exceeding 1 ppb would be expected to result in the permanent reduction of contaminant concentration in Komaine Creek sediment to levels below 1 ppb. It is anticipated that no subsequent excavation would be necessary to maintain sediment concentrations below 1 ppb. Complete excavation would remove all sediment from Romaine Creek, eliminating the potential for additional migration of existing contamination in Romaine Creek. As discussed later in this document, however, some degree of contaminant migration may occur from the adjacent Minker area, where soils exceeding 1 ppb TCOO were removed. Short-Term Effectiveness Short-term effectiveness measures how well an alternative provides protection of the environment, community, and workers during construction, and the time required for implementation. Short-term risk to public health and the environment would remain at current levels for Alternative 1. However, there would be no increase in risk to workers due to construction activity or disturbance of contaminated soil During implementation of Alternative 2, there would be low potential for exposure to workers and no significant increase in exposure to the community. or environment. Stabilization of the creek bed would result in greater potential for worker exposure due to soil-disturbing activities. Soil disturbance would increase the potential for exposure to the community and could temporarily disturb wildlife and increase stream turbidity. Excavation and interim storage of contaminated sediments would also involve soil disturbance and related exposure opportunities. This exposure potential could be mitigated by adequate dust control and monitoring. Severe storms may spread contamination during implementation of stabilization or excavation activities. Complete excavation of Romaine Creek sediments would involve a larger area with greater opportunity for wildlife disturbance and community and worker exposure. Disturbance of submerged sediments during removal in the perennial reach of the stream would increase the turbidity of lower Romaine Creek and temporarily increase sediment loading into the Meramec River. Exposure potential would continue during dewatering of submerged sediments. The potential negative effects of these possible events could be minimized and controlled by design and "Implementation of protective measures such as daily cover of exposed areas and removal of submerged sediments during low-flow periods. Long-Term Effectiveness Long-term effectiveness addresses the long-term protection and reliability that an alternative affords. This includes the risk to the community once the remedy is in place, risk to workers during operation and maintenance ------- 10 (0AM), environmental risk due to residual hazardous substances, long-term reliability, 0AM requirements, time required to achieve protection, and the difficulty in detecting and mitigating problems with the completed remedy. Existing contamination would remain in place for the no-action and limited-action alternatives. Site boundaries could potentially expand due to contaminant migration through erosion. If this occurred, the resulting increased volume of contaminated sediment would increase the scope and cost of future management. Excavation of sediments in the perennial portion of the stream would be much more difficult than in the intermittent section, if migration occurred to that extent. Limited action would.provide a monitoring program to detect the spread of contamination, and fencing to control access to contaminated portions of the creek. Fencing and posting of the creek may not prevent all site intruders from access. Limited action would have low 0AM requirements, could be easily inspected, and repairs would be straightforward. Limited action would achieve its full degree of protection immediately upon implementation of the remedy, as would all of the alternatives evaluated. Stabilization of the creek would reduce exposure potential to the community and environment by controlling dispersion of contaminated soil due to erosion by wind and water. Existing levels of contamination would remain in place. Bioaccumulation could continue to occur at a reduced rate. Operation and maintenance requirements would be substantial in order to maintain vegetation in all contaminated portions of the creek. Quarterly O&M may not be sufficient to maintain vegetation in some areas. Ineffectiveness of th« stabilization could result in migration of contaminants, expanded site boundaries, and increased sediment volumes requiring future management. Workers performing O&M activities could potentially be exposed to elevated levels of TCDO. If contaminants exceeding a level of concern were transported to the perennial portion of the creek, excavation would be more difficult. Excavation of contaminated sediment exceeding 1 ppb would reduce exposure potential to residential standards. Bioaccumulation of TCDO in biota could potentially continue to occur following excavation of sediments exceeding 1 ppb, but the rate of bioaccumulation would be expected to be substantially reduced from current levels. It is expected that reduction of contaminant levels in Romaine Creek to levels below 1 ppb would result in a reduction in contaminant levels in Romaine Creek biota. At the present time, bioaccumulation of dioxin in biota does not represent a significant risk to human health, since Romaine Creek and the extreme lower portion of Saline Creek do not support private or commercial fishing. Romaine Creek waters eventually reach the Meramec River, which currently has a state-issued fishing advisory in place due to elevated levels of chlordane detected in Meramec River fish. Contaminated biota in Romaine Creek and the Meramec River are therefore not expected to enter the human food chain or represent a current risk to public nealth. Limited 0AM requirements would be associated with maintaining the storage structures for both excavation alternatives. There would be no 0AM requirements for the creek, although annual monitoring of the area is included in the ------- 11 partial excavation alternative evaluated In the OUFS. Problems with the remedy could easily be detected during Inspection of the storage structures and repaired. The risk of system failure Is very low. Excavation and interim onsite storage of all sediments in Romaine Creek would provide the maximum degree of long-term protection to public health and the environment of the alternatives evaluated. No residual contamination would remain in the creek. Exposure potential for the community and environ- ment and the potential for bioaccumulation in the creek would be eliminated. Contaminant concentrations in affected biota would be expected to eventually return to background levels if no recontamination of the creek occurred. Limited U&M requirements would be associated with the storage structures. Problems with the remedy could be easily detected during inspection and repaired. Permanence The criteria of permanence 1s similar to long-term effectiveness, but with an emphasis on the need for management of treated residuals and untreated wastes. The operable unit alternatives evaluated represent interim measures which can be Implemented prior to final management of the contaminated soils. Permanence of each operable unit alternative concerns the extent to which future management of contaminated soils will be necessary. No action and limited action will not control migration of contaminated sediments, which could result in expanded site boundaries. A removal action Involving excavation of dioxin-contaminated soils exceeding 1 ppb has been completed at the Minker portion of the Minker/Stout/Romaine Creek site, which was the primary source of contamindf on Into Romaine Creek. It 1s therefore likely that dioxin concentrations 1n upper Romaine Creek will decline due to the erosion of contaminated sediments to downstream areas. Implementation of the no-action and limited-action alternatives will have no direct impact on future management requirements, although the volume of sediments requiring management could either decrease due to washout of contaminated areas or Increase due to downstream migration of contamination. Stabilization could be effective at controlling migration of contaminated sediment, thereby fixing the volume of sediment which is contaminated 1n excess of 1 ppb at the current level. Tnere would be some increase in future management requirements due to the need to manage the stabilization materials. Partial excavation of sediment 1s expected to result in the permanent reduction of contaminated levels to below 1 ppb. Future management of soils would be facilitated due to containerization of wastes. Complete excavation of contaminated sediments would permanently remove all existing contamination from Romaine Creek, but residual contamination at levels less than 1 ppb may continue to erode from the Minker area into Romaine Creek. It 1s not expected that this migration will result 1n recontamination of the creek to levels exceeding 1 ppb. ------- 12 Implementability This criteria measures the technical difficulties, reliability, and availability of each alternative. Implementability also involves the administrative feasibility of each alternative. No permits would be required for any of the actions evaluated since CERCLA onsite actions are exempt from permitting requirements by law. The implementability criteria does not apply to the no-action alternative, since no measures would be taken to mitigate the contamination. Implementation of limited action would be straightforward. Access to private properties adjacent to the affected portion of the stream would be required, and may 1n some cases be difficult to obtain. The reliability of the limited action alternative is not certain. Site intruders could ignore warning signs and scale or avoid fences. Contamination may migrate downstream resulting in additional areas requiring access restrictions. Stabilization of contaminated areas would be more difficult to successfully Implement than the no-action or limited-action alternatives. Many contaminated areas may not support vegetation. The reliability of stabilization would be Impacted by severe storms which could disrupt the stabilized areas. Access to private properties adjacent to contaminated portions of Romaine Creek would be required.and may be difficult to obtain. The construction of access roads would be required along the length of the creek .impacted for stabilization, and also for partial excavation and complete excavation alternatives. This may increase the difficulty in obtaining access from adjacent property owners. Imp lenient at ion of the partial excavation alternative could be facilitated by appropriate construction techniques. Vacuum equipment could be used to selectively remove pockets of sediment disposition within the creek. The reliability of partial excavation would be very high upon completion. The storage structures would last indefinitely if properly maintained. Implementation of the complete excavation alternative would be more difficult since submerged sediment would be removed from the creek. Dewatering of the dredged sediment would be a complex operation probably requiring several acres of land currently in private ownership. Difficulty would be expected 1n obtaining access on private property for construction of access roads, excavation activities, and dewatering. Cost The total present worth cost of each alternative is presented in Table I. Costs listed for Alternatives 4 and b involving excavation and interim storage include the cost of removal and decontamination of the storage structures upon Implementation of final management of sediment. Also included in Table I is the .estimated annual Operation and Maintenance (OSM) cost associated with each alternative. ------- 13 Community and State Acceptance Duriny past public meetings conducted for other portions of the Mlnker/Stout/ Romaine Creek site and other nearby dloxin sites, tne community was given the opportunity to express their preference for management of contaminated soils. Affected residents are in general agreement that the contaminated soil should be excavated and transported offsite for treatment or disposal. At tne present time, there is no offsite treatment or disposal facility capable of managing the dioxin-contaminated sediments. Interim storage is therefore necessary until an offsite management option develops. The community is likely to be supportive of excavation of contaminated sediment and removal of the associated risk to public health. Given the absence of an offsite management option, the public will probably accept interim storage as the only alternative available at this time. Interim storage is consistent with the community supported final management option of offsite treatment or disposal. Some local objection can be expected near the location where the required storage structures are sited. Several removal actions have been completed in the recent past involving excavation and interim storage of contaminated soils at nearby Eastern Missouri dioxin sites. The State of Missouri has in the past been supportive of these actions if they achieve adequate protection of public health and the environment. During the public comment period, the state expressed Its support for the excavation and interim storage of sediments exceeding 1 ppb in Romaine Creek. . ' SELECTED REMEDY DESCRIPTION OF THE SELECTED REMEDY The interim remedy which the Agency will implement as an operable unit remedial action involves excavation of creek sediments exceeding 1 ppb 2,3,7,8 TCDO. This remedy is developed and described in detail as Alternative in the Romaine Creek Operable Unit Feasibility Study. Excavation of Romaine Creek soils and sediments exceeding 1 ppb will be performed using vacuum equipment, or other appropriate means of selectively removing pockets of potentially contaminated sediment deposition. An effort will be made to minimize the amount of material removed from Romaine Creek, while maintaining the assurance that soils and sediment exceeding 1 ppb are not left in place. Minimizing the volume of sediment removed from Romaine Creek limits the extent of environmental disturbance within the creek. Minimizing the removed sediment volume also reduces the required interim storage space and associated final management costs for the removed material. Any identified technology or procedure capable of reducing the amount of material removed from Romaine Creek will be investigated during the design phase. These technologies include, but are not limited to, innovative excavation techniques and particle separation technologies capable of separating the contaminated fine materials from uncontaminated rocks and other coarser materials. ------- 14 All concentrations within Romaine creeic will be determined at the 95 percent confidence level using the procedure developed in 1984 for cleanup of other eastern Missouri dioxin sites. This procedure has undergone peer review and approval by Federal and State health agencies including the Centers for Disease Control/ Center for Environmental Health, Environmental Protection Agency, Missouri Division of Health, and the Missouri Department of Natural Resources. This procedure determines the maximum surface contaminant level in unit areas of approximately b,uOO square feet or smaller at the 9b percent confidence level. txcavated soil and sediment will be containerized in woven polypropylene, polyethylene-lined bulk handling sacks similar to those currently and previously in use at eastern Missouri dioxin sites, including the Minker, Cashel, and SulHns portions of the Minker/Stout/Komaine Creek site. These bulk-handling sacks will be loaded by hopper and transported to fully enclosed, temporary storage structures constructed onsite. Storage structure design will be similar to those in use at other eastern Missouri dioxin sites. One 50-foot by 100-foot building has a capacity of approximately 1,100 cubic yards of containerized material. It is estimated that up to four such structures will be required to store the volume of contaminated material anticipated to be removed from Romaine Creek. Storage structures for contaminated material excavated from Romaine Creek will be located on the former Edwards property. The storage structures will be protected from flooding, and an effort will be made to minimize their adverse aesthetic impact. Excavated materials will be placed in interim storage until a final management .option can be selected. If a fi.nal management alternative becomes available and is selected in a separate Record of Decision for material removed from Romaine Creek, it is possible thac interim storage of the excavated material will not be necessary, and that contaminated soil and sediment can be taken directly to the location where final managenent is available. This decision would be documented in a subsequent Record of Decision for final management of dioxin-contaminated materials from the Minker/Stout/Romaine Creek site. The interim remedy also includes a provision for annual monitoring. This monitoring will verify that the interim remedy remains protective of public health and the environment. Contaminant levels will be monitored in sediment and biota. Area wells will also be sampled to confirm that area groundwater used for domestic purposes does not become contaminated. If TCDD levels are consistently below a level of concern for public health and the environment, this monitoring may be discontinued. RATIONALE FOR PREFERENCE The selected interim remedy is preferred over the no-action and limited-action alternatives primarily because leaving contaminated sediment in place does not provide adequate protection of human health or the environment. Access to contaminated portions of the creek by nearby residents or visitors would not be prevented by either no-action or limited-action alternatives. Exposure via direct contact and ingestion would continue to occur in excess of a level of concern for protection of human health -in residential areas recommended by federal and state health agencies. ------- 15 Naturally occurring erosion processes would be expected to gradually reduce contaminant levels in Romaine Creek. This erosion would result in the more highly contaminated sediment being transported downstream where it could become available to additional environmental and human receptors. Existing contaminant levels in Komaine Creek are too high to allow natural erosion processes to transport contaminated sediment downstream in an unmanaged process. It is expected that natural attenuation of contaminant levels to a level considered protective of public health and the environment could potentially take many years. Exposure of the public and environmental receptors to levels considered unsafe could continue until sediment concentrations are greatly reduced. Allowing natural processes to reduce sediment concentrations does not provide adequate protection of human health or the environment. Stabilization of contaminated sediments is not being proposed due to the uncertainty of successful implementation, high OiM requirements, and because final management of the contaminated sediments would involve future construction activities which would disturb the creek and adjacent property owners along the contaminated portion an additional time. Difficulty may be encountered in acquiring easements or other types of access to private properties in order to perform regular maintenance. Excavation of contaminated sediments would permanently remove contaminants from Romaine Creek and eliminate the need to' perform additional construction activities prior to final management of contaminated sediment. STATUTORY DETERMINATIONS Removal and temporary onsite storage of soils and .sediment exceeding 1 ppb in Romaine Creek attains the objectives of- the interim -emedy and satisfies the remedy selection criteria. The objectives of the ^nterim remedy identified in the Romaine Creek Operable Feasibility Study are to protect human health and the environment, provide compatibility with potential final remedial actions, and be cost-effective. Protection of human health and the environment is provided by mitigating the potential for human and environmental contact with contaminated sediment and reducing the potential for continued downstream erosion of contaminated sediments. The proposed interim remedy attains protectiveness objective by isolating the containerized contaminated sediment in a secure storage facility, thereby eliminating the potential for human or environmental contact with contaminated material exceeding 1 ppb TCDO. Some migracion of sediments left in place at concentrations less than 1 ppb may continue to occur, but this migration is not expected to result in the development of contaminant levels exceeding a level of concern for protection of public health and the environment in the creek. It is anticipated that natural degradation and erosion processes will result in the gradual reduction of contaminant levels in the creek to near background levels. The selected interim remedy also attains the objective of compatibility with final remedies. The interim remedy is compatible with potential offsite treatment or disposal options. Future handling of the contaminated material will be facilitated by containerization. The interim remedy is ------- 16 not compatible with final remedial action alternatives, involving in-place containment or treatment. In-place alternatives, however, do not compare favorably to offsite alternatives for final management of contaminated sediment, and have not been recommended by the Agency for implementation at Komaine Creek. Although a final remedy has not been selected for contaminated soils and sediment from the Minker/Stout/Romaine Creek site, the Agency has proposed offsite thermal treatment for final management of this material. This proposed final remedy is supported by SARA, which establishes a statutory preference for remedies wnich utilize treatment technologies that result in the permanent reduction in toxicity, mobility, or volume of the hazardous mater? a 1. The selected remedy has been determined to be the most cost-effective operable unit remedial alternative which provides protectiveness. Only the two removal alternatives evaluated will assure the continued protection of public health and the environment. Complete excavation of all sediments in Komaine Creek cannot be justified at the additional cost because both removal alternatives reduce TCDD concentrations below 1 ppb which assures protection of public health and the environment. Complete excavation of sediments would result in excessive disruption of the environment along the entire length of Romaine Creek and would be very difficult to implement. Removal of all sediment in Romaine Creek may not permanently remove all contamination from the streambed since soil with TCDD concentrations less than 1 ppb may continue to erode into the creek from the Minker area. The 1 ppb action level utilized during the cleanup, of the'Minker area does provide protection of human health in Romaine Cree<, where consumption of contaminated biota 1s not expected, to represent an additional public health risk.. The Missouri Department of Conservation has stated Romaine Creek does not support fishing and adjacent" residents have confirmed this by reporting that no fishing has been observed. Romaine Creek flows into Saline Creek 0.2 miles upstream o'f the Meramec River. The Meramec River is currently under a state-issued fish advisory due to elevated chlordane levels in the fish. TCOO levels detected in Meramec River biota to date have not, however, exceeded a Food and Drug Administration (FDA) advisory level for consumption of fish from the Great Laices of bO parts per trillion (ppt). Consumption of contaminated fish from Romaine Creek or the Meramec River is therefore not expected to be a significant pathway of human exposure. Removal of soil exceeding 1 ppb at the Minker area has eliminated the source of highly contaminated sediment into Romaine Creek. It is anticipated that following removal of sediment exceeding 1 ppb in Romaine Creek, residual contaminant levels in the creek will gradually decline due to naturally occurring degradation and erosion processes. The selected Interim remedy includes annual monitoring of Komaine Creek following removal of sediments exceeding 1 ppb in order to monitor residual contaminant levels and detect any potential migration or accumulation of contaminated sediments. It is anticipated that contaminant levels will gradually return to background. Bioaccumulated contaminant levels in biota are expected to decline following removal of sediment exceeding 1 ppb. As residual sediment concentrations are further reduced through natural processes, a corresponding decline in biota contaminant levels is expected. Annual monitoring of sediment and biota will monitor the reduction in contaminant levels following implementation. ------- |