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Home My WebLink AboutNCD986175644_19980728_Davis Park Road TCE Site_FRBCERCLA PM CI_Public Meetings-OCR, ,. Meeting Notice The Environmental Protection Agency will conduct a Proposed Plan public meeting on July 2Efh beginning at 7:00PM in the auditorium of the Taylor Memorial Baptist Church 2616 Davis Park Road Gastonia, N. C. to present the results of the Remedial Investigation and possible cleanup/treatment options available for the Davis Park Road TCE Site. The Proposed Plan fact sheet providing this information will be mailed on July 2:l"d to citizens on the Site's mailing list. The public comment period starts on July 27 and ends August 26, 1998. If you have any questions in the meantime, please contact Diane Barrett, EPA Community Involvement Coordinator at 1-800-435-9233. ft ~ Region.; • U.S. Environmental Protection Agency 61 Forsyth Street, SW Atlanta, Georgia 30303-3014 ..... . ' . l --_,,_ .. :·· .. =---, North Site Management B4c~ j-1 iv~ ; •ENAC'~ 5 '''"'"''"· -~ !, Diane Barrett, Community Re~.ti~'!ll Copr<!.;~~Ars O O 3 7 1\' Jennifer Wendel, Remedial Project Manager'525300 ' -* \ / \ . .ec7•A • )fficial Business >enalty tor Private Use $300 S/F ------.. ----· --, OPRD0071 . PUBLIC !NF □• ASST. NC SUPERFUND SECTION HEALTH NC DEPT. OF ENYIRONMENT, & NATURAL RESOURCES , P.O. BOX 27687 j (_RA_L_E_r_GH ____________ NC 21~1~-~6-B~ __ RECEI\/ED JUL 15 1998 SUPERFUND SECi\Ot . ' 2.7!:-i i-7i:-87 .I,, l. Ii,! I\, ll. I! I! llll I Ill, I! I, ll,, I,! I, I 11111,, 1,l, I! 1 ll,, ,l DAVIS PARK ROAD SITE Gastonia, North Carolina PROPOSED PLAN PUBLIC MEETING AGENDA July 28, 1998 Taylor Memorial Baptist Church 2616 Davis Park Road Gastonia, North Carolina AGENDA: Welcome, Introductions and Diane Barrett Purpose of Meeting Community Involvement Coordinator (Approx. 5 minutes) Brief Site History Jennifer Wendel Overview of Alternatives Remedial Project Manager Presentation of Preferred Alternative (Approx. 25 minutes) Question and Answer Period NOTES Closing Remarks/ Adjournment • • SUPERFUND PROCESS ENFORCEMENT ACTIVITIES , SITE DISCOVERY I CLEANUP PU>l'')--tl►-( DESICH 1 LONG-TERM CLU.NUP COMMUNITY RELATIONS IN 1980, CONGRESS ENACTED THE COMPREHENSIVE ENVIRONMENTAL REPONSE, COMPENSATION, AND LIABILITY ACT (CERCLA). THIS ACT CREATED A TRUST FUND, KNOWN AS -SUPERFUND-, TO INVESTIGATE AND CLEAN UP ABANDONED OR UNCONTROLLED HAZARDOUS WASTE SITES. MODIFIED IN 1986 BY THE SUPER FUND AMENDMENTS AND REAUTHORIZATION ACT(SARA). THE ACT AUTHORIZES EPA TO RESPOND TO RELEASES OR THREATENED RELEASES OF HAZARDOUS SUBSTANCES THAT MAY ENDANGER PUBLIC HEALTH OR WELFARE, OR THE ENVIRONMENT. THE 1982 SUPER FUND NATIONAL OIL AND HAZARDOUS SUBSTANCES CONTINGENCY PLAN (NCP), REVISED IN 1988, DESCRIBES HOW EPA WILL RESPOND TO MEET THESE MANDATES. THIS EXHIBIT PROVIDES A SIMPLIFIED EXPLANATION OF HOW A LONG-TERM SUPERFUND RESPONSE WORKS. 1. AFTER A SITE IS DISCOVERED, IT IS INVESTIGATED, USUALLY BY THE STATE. 2. THE EPA OR ITS REPRESENTATIVE THEN RANKS THE SITE USING THE HAZARD RANKING SYSTEM (HRS), WHICH TAKES INTO ACCOUNT: -POSSIBLE HEAL TH RISKS TO THE HUMAN POPULATION -POTENTIAL HAZARDS (E.G.,FROM DIRECT CONTACT, INHALATION, FIRE, OR EXPLOSION) OF SUBSTANCES AT THE SITE -POTENTIAL FOR THE SUBSTANCES AT THE SITE TO CONTAMINATE DRINKING WATER SUPPLIES -POTENTIAL FOR THE SUBSTANCES AT THE SITE TO POLLUTE OR OTHERWISE HARM THE ENVIRONMENT. If THE PROBLEMS AT A SITE ARE DEEMED SERIOUS BY THE STATE AND THE EPA. THE SITE WILL BE LISTED ON THE NATIONAL . PRIORITIES LIST (NPL), A ROSTER OF THE NATION'S HAZARDOUS WASTE SITES WHICH ARE ELIGIBLE FOR FEDERAL SUPERFUND MONEY. · If A SITE OR ANY PORTION THEREOF POSES AN IMMINENT THREAT TO PUBLIC HEALTH OR THE ENVIRONMENT AT ANYTIME, EPA MAY CONDUCT AN EMERGENCY RESPONSE REFERRED TO AS AN IMMEDIATE REMOVAL ACTION. 3. NEXT, EPA USUALLY CONDUCTS A REMEDIAL INVESTIGATION (RI), THE RI ASSESSES HOW SERIOUS THE CONTAMINATION IS, WHAT KIND OF CONTAMINANTS ARE PRESENT, AND CHARACTERIZES POTENTIAL RISKS TO THE COMMUNITY. AS PART OF THE RI, EPA TYPICALLY CONDUCTS AN ENDANGERMENT ASSESSMENT THAT DESCRIBES THE PROBLEMS AT THE SITE AND THE POTENTIAL HEAL TH AND ENVIRONMENT AL CONSEQUENCES IF NO FURTHER ACTION IS TAKEN AT THE SITE. 4. FOLLOWING COMPLETION OF THE RI, EPA PERFORMS A FEASIBILITY STUDY (FS) WHICH EXAMINES VARIOUS CLEANUP ALTERNATIVES AND EVALUATES THEM ON THE BASIS OF TECHNICAL FEASIBILITY, PUBLIC HEALTH EFFECTS, ENVIRONMENTAL IMPACTS, INSTITUTIONAL CONCERNS (INCLUDING COMPLIANCE WITH STATE AND LOCAL LAWS), IMPACT ON THE COMMUNITY, AND COST. THE FINDINGS ARE PRESENTED IN A DRAFT FS REPORT. 5. FOLLOWING COMPLETION OF THE DRAFT FS REPORT, EPA HOLDS A PUBLIC COMMENT PERIOD,TO RECEIVE CITIZEN INPUT. CONCERNING THE RECOMMENDED ALTERNATIVES. CITIZENS MAY PROVIDE COMMENTS EITHER CRALL Y AT THE PUBLIC MEETING OR THROUGH WRITTEN CORRESPONDENCE TO EPA. 6. AFTER PUBLIC COMMENTS HAVE BEEN RECEIVED, EPA RESPONDS TO THE COMMENTS IN THE RESPONSIVENESS SUMMARY PART OF THE RECORD OF DECISION (ROD) WHICH IDENTIFIES THE SPECIFIC CLEANUP PLAN. 7. ONCE THE DESIGN IS FINISHED, THE ACTUAL REMEDIAL ACTIVITIES OR CLEANUP OF THE SITE CAN BEGIN. THE TIME NECESSARY TO COMPLETE EACH OF THESE STEPS VARIES WITH EVERY SITE. IN GENERAL, AN RltFS TAKES FROM ONE TO TWO YEARS. DESIGNING THE CLEANUP PLAN MAY TAKE SIX MONTHS AND IMPLEMENTING THE REMEDY· THE ACTUAL CONTAINMENT OR REMOVAL OF THE WASTE-MAY TAKE FROM ONE TO THREE YEARS. IF GROUNDWATER IS INVOLVED, THE FINAL CLEANUP MAY TAKE MANY MORE YEARS. COMMUNITY RELATIONS ACTIVITIES DURING A CLEANUP INCLUDE PUBLIC MEETINGS AND OTHER ACTIVITIES INTENDED TO KEEP CITIZENS AND OFFICIALS INFORMED AND TO ENCOURAGE PUBLIC INPUT. THESE ACTIVITIES ARE SCHEDULED THROUGHOUT THE SUPERFUND PROCESS, SPECIFIC ACTIVrTIES VARY FROM SITE TO SITE DEPENDING ON THE LEVEL OF INTEREST AND NATURE OF CONCERN. THE RANGE OF COMMUNITY RELATIONS ACTIVITIES THAT CAN OCCUR IS DESCRIBED IN THE EPA'S COMMUNITY RELATIONS PLAN FOR THE SITE. ALL DOCUMENTS RELATING TO THE SITE ARE AVAILABLE FOR PUBLIC REVIEW AND COPYING IN THE DESIGNATED INFORMATION REPOSITORIES. - . . . ':·' :::. . . ,. : . :· :· .. ,.::,:_ . . . . . . : :; ' . . Gasto~ia, Gaston County, North Carolina Proposed Plan Public Meeting Tuesday, July 28, 1998 7:00 P .. M .. Taylor Memorial Baptist Church Meeting Agenda · Welcome g Introduction of Participants (Diane Barrett, Community Relations Coordinator) Meeting Purpose, Review of ~ommunity Relations Activities g Overview of Superfund (Diane Barrett, Community Relations Coordinator) Site Description, History, Results of Remedial Investigation, Baseline Risk Assessment, g Feasibility Study .· . . . .·. . . .. (Jennifer Wendel, Rernedial· Project Manager) Meeting Agenda Remedial Alternatives and EPA's Preferred Alternative (Jennifer Wendel. Remedial Project Manager) Question and Answer Session (Jennifer Wendel, Remedial Project Manager) .~. . .:.-,;-.. · . Site Background/History Site Consists of the building currently occupied by the Davis Park Auto Repair Shop and a Groundwater Contaminant Plume The building has been occupied by numerous businesses beginning in 19 56 Suspected source of current groundwater contamination because of previous sampling efforts··•·.··. · · · · Site Background/History 1991 Site Investigation Conducted by North Carolina Department of Environment and Natural Resources 199 I Investigation revealed soils behind the building now occupied by Davis Park Auto Repair were contaminated with· TCE and PCE A follow-up investigation conducted at the request of EPA cpnfirmed these results ~ ,. Site Background/History 1994 Expanded Site Investigation conducted by NCDENR revealed that soil contamination levels had dropped significantly · TCE and 1,2-DCE were detected, but no PCE Some petroleum-type compounds were also detected at low levels Site Background/History · The investigation of possible groundwater contamination began i!1 March of 1990 Between 1990 and 1992, Gaston County Health Officials and State Personnel collected 2 2 . groundwater samples from private wells in the vicinity of the Site 14 of the samples contained detectable levels of TCE or PCE, or.bo.th · . . . . : . : .· . .: .. . . . .. = ::· . . ' . < . ·: . . . . . The I 994 investigationiconfirmed contamination···••······ .. · : i~ fiy~ ~t ~mi ~~~~i2g§J~ §~tffi~I~~ ~.~!l§ I Ift:'.{}:}:l:t;::;::;~~:1t-1::;r~: :I~:t:fiii~I:;:t,i:;;f \itIIif Jj:::Iti:tI/t:r::I:T Remedial Investigation ·Findings The Remedial Investigation (RI) was conducted in three phases from 1996-1998 Environmental Samples taken from: Surface Soils Subsurface Soils Groundwater . Surface Water and Sediment from Blackwood Creek and Crowders Creek Remedial Investigation Findings Some petroleum-type compounds detected at low levels in 1996 By the Spring of 1998, only one VOC, a common lab contaminant, was detected in the soils · Contaminants previously found in soils, most notably PCE and TCE, hav~ migrated into the groundwater . . . . . . - . No continued source · ··· ·· ntamination remains in · ..... Remedial Investigation Findings Soil sampling conducted to determine if continuing source of contamination exists Extensive surface· and subsurface soil sampling · conducted on the property of the Davis Park Road Auto Repair Shop . By 1996, no PCE, TCE or I ,2-DCE detected in · soils . . . .. Remedial Investigation ~indings · The only media where significant levels of contamination were foL1nd was the groundwater The contaminants of concern in the groundwater were all VOCs: TCE PCE Methyl-tert butyl-ether · Chlorof or111 · Contaminants of Concern and Drinking Water Standards All concentrations reported in micrograms per Liter or Parts per Billion A -indicates only an average value could be reported for this contaminant Contaminant Highest of Concern Concentration Detected MCL PCE 14 5 TCE 34 5 . MTBE 790 -- 1, 1-DCE 3.8 7 Chloroform 100 NC Groundwater 2L Standard 0.7 2.8 7 0.19 Risk Assessment · In order for there to be a RISK, the following criteria should be met: ----· -A route or pathway leading to exposure -Chemicals exposed to have some degree of toxicity -Contaminant levels exceed a •. published standard ... Summary of Risk Assessment Exposure to Groundwater Carcinogenic Risk Non- Carcnogenic Risk Child Adult Child Adult Resident Resident Resident Resident (Top of (Top of (Bedrock) (Bedrock) Bedrock) Bedrock) None Unaccept. Risk 5.1 None Unaccept. Risk 2.2 Within Acceptable Risk Range 3.9E-05 Unaccept. Risk 1.25 Within Acceptable Risk Range 6.7E-05 No Unaccept. Risk Feasibility Study Evaluation Process Step I -Screening of Technologies Step 2 -Development of Remedial Alternatives Step 3 -Screening Evaluation of Remedial Alternatives ·· Step 4 -Detailed Analysis of Remedial · Alternatives · Detailed Analysis of Remedial . · Alternatives THRESHOLD CRITERIA I . Overall Protection of Human Health and the Environment· 2. Compliance with Applicable or Relevant and Appropriate. Requirements (;\RARs) Detailed Analysis of Remedial Alternatives ·•• EVALUATING CRITERIA 3. Long-Term Effectiveness 4. Reduction of Contaminant Toxicity, Mobility and Volume 5. Short-Term Effectiveness Detailed Analysis of Remedial Alternatives · · MODIFYING CRITERIA . 8. State Acceptance 9. Community Acceptance Alternatives Evaluated Alternative Description Present Worth· Costs Alternative 1 No Action $140,055 Alternative 2 Institutional Controls $990,225 Alternative 3 Reduction of Groundwater $3,873,299 Exposure and Monitored Natural Attenuation Alternative 4 Reduction of Groundwater $9,894,308 Exposure and Groundwater Treatment Alternative 5 Reduction of Groundwater $6,562,349 Exposure and Groundwater Pump and Treat NATURAL ATTENUATION The "natural attenuation processes" that are at work in a remediation approach include a variety of physical, chemical, or biological processes that, under favorable conditions, act without human intervention to reduce the mass, toxicity, mobility, volume, or concentration of contaminants in soil or groundwater. These in-situ processes include biodegradation; dispersion; dilution; sorption; volatilization; and che111ical or biological stabilization, transformation, or destruction of contaminants. EPA 's Preferred Alternative J-\Jt~J'JJ;Jtjve 3 Reduction of Groundwater Exposure and Monitored Natural Attenuation Total Present Worth Cost $3,873,299 , . Contingency Remedy In the event that Natural Attenuation ceases to reduce the concentration of contaminants in the groundwater, EPA will implement a contingency remedy: · J\Jt=rr J:Jt} V= 5 Groundwater Exposure Reduction and Groundwater Pump and Treat · Total Present Worth Cost $6,562,349 .. . . SUPERFUND PROPOSED PLAN FACT SHEET • DAVIS PARK Rc!Ao JCE SITE GASTONIA, GASTON COUNTY, NORTH CAROLINA July 27, 1998 This fact sheet is not considered as a technical document, but has been prepared for the general public to provide a better understanding of the proposed activities at the Davis Park Road Site. Words appearing in bold print are defined in a glossary at the end of this publication. INTRODUCTION This Proposed Plan identifies the preferred options for cleaning up contaminated groundwater at the Davis Park Road TCE Site (Davis Park Road Site) in Gastonia, North Carolina. This document is being issued by the U.S. Environmental Protection Agency (EPA), the lead agency for Site activities, and the North Carolina Department of Environment, and Natural Resources (NC DENR), the support agency. EPA, in consultation with NC DENR, conducted the Remedial Investigation (RI) and Feasibility Study (FS). A remedy for the Davis Park Road Site will be selected only after the public comment period has ended and all information submitted to EPA during this time has been reviewed and considered. EPA is issuing this Proposed Plan as part of its public participation responsibilities under Section 11 ?(a) of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), also known as Superfund. This document summarizes information that is explained in greater detail in the RI/FS reports and other documents contained in the Information Repository/Administrative Record for this Site. EPA and the State encourage the public to review these documents to better understand the Site and Superfund activities that have been conducted. The Administrative Record is available for public review locally at the Gaston County Public Library. EPA, in consultation with NC DENR, may modify the preferred alternative or select another response action presented in this Plan and the RI/FS reports based on new information and/or public comments. Therefore, the public is encouraged to review and comment on all alternatives identified here. THIS PROPOSED PLAN: 1. Includes a brief history of the Site and the principal findings of Site investigations; 2. Presents tt,e alternatives for the Site considered by EPA; PUBLIC MEETING WHEN: July 28, 1998 WHERE: Taylor Memorial Baptist Church 2616 Davis Park Road Gastonia, NC TIME: 7:00 PM -9:00 PM PUBLIC COMMENT PERIOD: JULY 27 -AUGUST 26, 1998 • 3. Outlines the criteria used by EPA to recommend an alternative for use at the Site; 4. Provides a summary of the analysis of alternatives; 5. Informs the public that the EPA is proposing to issue a Record of Decision (ROD) for the Site which includes a contingent alternative; and 6. Explains the opportunities for the public to comment on the remedial alternatives. SITE BACKGROUND The Davis Park Road Site is located in a mixed residential and small business neighborhood along Davis Park Road, south of Hudson Boulevard and north of Blackwood Creek in the southwestern portion of Gastonia, Gaston County, North Carolina. The Site also includes the Cedar Oak Park Subdivision located on the east side of Davis Park Road, within the confines of Cedar Oak Circle, as well as areas along the western side of Davis Park Road. During the RI the soil behind the building that i.; currently occupied by the Davis Park Auto Repair shop at 2307 Davis Park Road, · and a plume of contaminated groundwater that was believed to emanate from this property, were investigated. Figure 1 shows the approximate RI study area of the Davis Park Road Site. The Davis Park Road Site will be proposed for inclusion on the National Priorities List (NPL) in September of this year. The building at 2307 Davis Park Road has been owned by Carl Bell (now deceased) and Douglas Bell of Gastonia and Charlotte, respectively, since 1960. Carl Bell leased the property to Acme Petroleum and Fuel Company (ACME) of Gastonia in 1966. ACME held this lease until 1981. During the lease period, the property was subleased to various service stations and repair shops. City of Gastonia records were consulted to identify businesses operating from 2307 Davis Park Road- the location of Davis Park Auto Repair. Accordingly, the following dates of operation and names of businesses were found: 1956 to 1957 1958 1959 to 1960 1961 to 1965 1965 to 1970 1971 to 1972 1973 to 1975 1976 to 1979 1980 to 1982 1983 to 1987 1988 to 1996 • No Business located on this property Burch's Grocery Johnny's Food Store/John A. Kersey Gastonia Food-O-Mart Davis Park Suprette Davis Park Suprette and Tim's Sports Cars (used cars) Davis Park Shell Station, Davis Park Suprette, and Tim's Sports Cars Davis Park Shell Station and Davis Park Suprette Clark's Transmission and Wrecker Service Moore's Transmission and General Mechanics Moore's Automatic Transmission and General Mechanics (Dates are approximate) Recently (late 1996 or early 1997), the name of the business in the building at 2307 Davis Park Road was changed to Davis Park Auto Repair. Plea~a refer to the RI Report !0cated in the Gaston County Public Library in Gastonia for further information on the history of subleasing and housekeeping practices at 2307 Davis Park Road. A 1991 Site Investigation conducted by NCDENR reported concentrations ofTCE (trichloroethylene) and PCE (tetrachloroethylene) as high as 700 parts per billion and 3,000 parts per billion, respectively, in soil samples collected from the drain pipe that exits at the back of the building at 2307 Davis Park Road. At the request of EPA, NCDENR prepared a Site Inspection Addendum report to the Site Investigation. This investigation confirmed the presence of PCE and TCE as well 1,2-DCE, (1,2-dichloroethane) a breakdown daughter product of PCE, in soil samples taken from the vicinity of the drain line. However, in a follow-up Expanded Site Investigation in 1994 conducted by NCDENR, the concentration of TCE in soil had dropped to 38 parts per billion and the concentration of 1,2-DCE, to between 4 and 20 parts per billion. In addition, petroleum-type compounds (toluene, ethylbenzene, total xylenes) were detected in the soil samples at very low levels. No PCE was detected in the soil samples. "' ~ i z ~ ~ i • ( 1 \ I ' ' 0 0 0 \ ' □ \_,--a\ Oct<O "\\__,- \ \ 0 H , ,, " H , 0 " " a a / _.,....,-----._~ __ _,~,,,,,,,-,,,al'l!MIS () ,. =--~ ,, ,, ,. " " " 11 DAVIS Cl t:JO D □ nou.NO AVt:NU£ \ •' PARK 11 AUTO 1'. REPAIR ,:, bc:JC:Jc::JOC::JC GI.EtmAVEN AVENUE C c, c:, <:I C, f;J c, 1 0 000 0 oo ,·a 0 :;o oo oo o ~ 0 Cl (:J i c:ioO 0, 0 0 i,D o \\ ' " " □ () • 0 0 " ~,o 0 C 0 □ D ___ .-·----- CJ lJ . 0 □ oo 0 0 c::, f ,, ,, ,, ,, ,, <:::, '' 1i •-"" SITE MAP DAVIS PARK ROAD TCE SITE GASTONIA, NORTH CAROLINA Approximate Scale In Feel ~ L--------------------------------------'------~0====~6~0~0====~,2~0~0~ • The investigation of possible groundwater contamination began on March 31, 1990, when a groundwater sample was collected by Gaston County Environmental Health representatives from a supply well within the Cedar Oak Park subdivision as part of a routine sampling procedure. Analysis of the sample revealed concentrations of TCE (34.9 part per billion), and PCE (23.7 part per billion). The State of North Carolina Drinking Water Standard for TCE is 2.8 parts per billion and for PCE is 0. 7 parts per billion. During April of that year, Gaston County Health Department officials collected samples from three nearby private wells. The sampling revealed the groundwater was contaminated with TCE, with the highest detected level (101.4 parts per billion) in a sample collected from the private well located at 2419 Davis Park Road, 200 feet south of the Davis Park Auto Repair building. During the Site Inspection Addendum work requested by EPA, the NCDENR and Gaston County Environmental Health Department personnel sampled 22 private wells in the vicinity of the Site. The sampling was conducted from May 1990 to August 1992. Fourteen of the samples contained a detectable amount of PCE or TCE or both. The 1994 Expanded Site Investigation confirmed contamination in five of the previously sampled wells. RESULTS OF THE REMEDIAL INVESTIGATION Samples were collected in the surface and subsurface soils, groundwater-from both the overburden (top-of bedrock) and bedrock aquifer systems, sediments and surface water. The RI was conducted in three phases beginning in 1996 and ending in the Spring of 1998. The only media where significant levels of contaminants were found was the groundwater. The contaminants of concern (COCs) were all VOCs, or volatile organic compounds (PCE, TCE, chloroform, MTBE (methyl-tert-butyl ether), and 1, 1- dichloroethene). Based upon data collected from the RI, the overburden aquifer is no longer contaminated with TCE and PCE. All of the groundwater samples collected during the last phase of the RI, in late • 1997 and early 1998, which were found to be contaminated, were set within the bedrock aquifer. The groundwater TCE and PCE plumes, both within the bedrock aquifer, are shown in Figures 2 and 3. The highest detected level of TCE was 34 parts per billion and the highest level of PCE detected was 14 parts per billion. Private wells or former private wells which were converted to monitoring wells exhibited the highest concentrations of TCE and PCE. All detections occurred in sampling points south to southeast, or downgradient, of the suspected source. The only contaminant of concern detected in the overburden aquifer (top-of-bedrock) was MTBE at 790 parts per billion, which is above the State of North Carolina Drinking Water Standard of 200 parts per billion. Extensive soil sampling was conducted during the RI to try to determine if a continuing source of contamination exists in soils behind the 2307 Davis Park Road building, the current location of the Davis Park Road Auto Repair Shop. According to sample data collected during the years 1990 through 1994, subsurface soils behind this building have been contaminated with VOCs at various level£. The voes have :~•eluded TCE, PCE, degradation products of PCE and TCE, and petroleum-type compounds. During the RI, soil samples were also collected from the site. However, by 1996 the analysis for VOC content in soils revealed compounds typical of petroleum- type products only. Sampling conducted during the second and third phases of the RI, as late as Spring of 1998, revealed a low estimated amount of just one compound, bromoform, which is a common laboratory contaminant and probably not attributable to the Site. The property behind the Davis Park Road Auto Repair Shop sits on top of a bedrock high area. It appears as though the contaminants which were previously detected in soils behind the property, most notably PCE and TCE, have migrated into the groundwater and that there is no detectable continuing source of contamination located within the soils. Therefore, no cleanup or treatment of the soils is necessary. For more information on the results of the RI, please refer to the RI report available for review in the Gaston County Public Library. CJ..P.f_l'I_Ofll( Cll'ICl [ PR □JCCT THU) DAVIS PARK ROAD TC[ SIT£ GASTONIA, GASTON COUNTY, tlORTII CAROLINA re[ CONCENTRATION ISOPLETH MAP 1997 / 1998 fl[LO ltNESTIGATION [STIWA!lD Allt:1,1,. 011:HI Qr ,-CC: (!,,,,J\) 1H 0(0~()('>( A~"- (n) llfflA(H.OIIOClHC,< CCNC:CHTJIAl\()'!1 1H U0:/1-. _, . 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ICM<:>< W-'J Ne. U. lOCAlfO Al fl< l'IIUIS(CTIOH OI OA""S ,Ml( ~0.o.l) J,H0 ITAC:C COA04 ~OAO UCV~1101! • HI.DJ• • "" .,, O.U00-071- C•D rll[ /U,'4(, OAVISTCE.C S-36 • SUMMARY OF SITE RISKS During the RI/FS, EPA analyzed and estimated the human health or environmental problems that could result if the groundwater contamination at the Davis Park Road Site is not cleaned up. This analysis is called a baseline risk assessment. In conducting this assessment, EPA focused on the human health effects that could result from long term (30 years) daily, direct exposure as a result of ingestion, inhalation, or dermal contact with groundwater which are contaminated with carcinogenic (cancer causing) chemicals. The baseline risk assessment also focused on the adverse health effects that could result from long- term (30 years) exposure to non-carcinogenic chemicals. EPA did not assess the risk to current residents based on the results of groundwater sampling because the detected levels of PCE and TCE exceed both Federal and State drinking water standards. The exceedance of these standards at the Davis Park Road Site is sufficient evidence for the EPA to conduct a remedial action to prevent exposure. In calculating risks to a population if no remedial action is taken, EPA evaluates the reasonable maximum exposure levels for current and future exposure scenarios to Site contaminants. Scenarios were developed for residents living or working on the Site. EPA considers a long-term resident, beginning as a young child, being exposed to Site contaminants daily for 30 years. This is used to determine the reasonable maximum exposure scenario for future exposure to the contamination at the Davis Park Road Site. EPA has concluded that the major risk to human health and the environment at the Site would result from the ingestion of groundwater contaminated with VOCs. For more information about the risk posed by the contamination at the Davis Park Road Site, please refer to the Baseline Risk Assessment Report available for review at the Gaston County Public Library. • REMEDIAL ACTION OBJECTIVES Remedial action objectives were developed based on the results of the risk assessment, and the examination of potential applicable or relevant and appropriate requirements (ARARs). Chemical-, action-, and location-specific ARARs were examined. Chemical-specific ARARs for groundwater include maximum contaminant levels (MCLs) and North Carolina groundwater standards. In some cases, the applicable standard is below the lowest detectable level, based on current laboratory practices. For those contaminants, the cleanup standard is based on the lowest detection limit for laboratory analysis. For the COCs, the applicable cleanup standards, in parts per billion, are: Chemical PCE TCE 1,1,-DCE Chloroform MTBE Standard 1 2.8 7 1 200 The objective of the Remedial Action for the Davis Park Road Site will be to return contaminated groundwater to beneficial use by reducing contaminant concentrations to below cleanup standards. SUMMARY OF REMEDIAL ALTERNATIVES The following section provides a summary of the alternatives developed in the FS Report for groundwater remediation. The primary objective of the FS was to determine and evaluate alternatives for cleaning up the groundwater at the Site. Descriptions of the clean-up alternatives are summarized below. The FS Report contains a more detailed evaluation/description of each alternative, and is available for review in the Information Repository located in the Gaston County Public Library. The cost information provided below for each alternative represents estimated capital cost, annual operation and maintenance (O&M), and present worth. Capital costs include construction, present worth. Capital costs intlie construction, engineering and design, equipment, and Site development. Operating costs were calculated for activities that continue after completion of construction, such as routine operation and maintenance of treatment equipment and groundwater monitoring. The present worth (PW) of an alternative is the amount of capital required to be deposited at the present time at a given interest rate to yield the total amount necessary to , pay for initial construction costs and future expenditures, including O&M, and future replacement of capital equipment. The alternatives are: ALTERNATIVE 1: NO ACTION Capital Costs: $0 PW O&M Costs: $140,055 Total PW Costs: $140,055 Duration to Achieve cleanup: CERCLA requires that the "No Action" alternative be evaluated at every site to establish a baseline for comparison. No further activities would be conducted with groundwater under this alternative. Because this alternative does not entail contaminant removal, a review of the remedy would be conducted every five years in accordance with the requirements of CERCLA. Operating costs are based on this five year review, which would include sampling of monitor and residential wells for the COCs and preparation of a report. There would be no maintenance costs. ALTERNATIVE 2: INSTITUTIONAL Capital Costs: PW O&M Costs: Total PW Costs: CONTROLS $ 26,750 $866,045 $990,225 Duration to Achieve Cleanup: This alternative includes deed recordations and groundwater monitoring. Deed recordations would require amending the property deed to note that contaminated groundwater is located on the property. These recordations would remain in place until the groundwater quality improved enough to allow for unrestricted use. Groundwater would be monitored at the eight existing overburden aquifer wells, six bedrock aquifer monitoring wells and four on-site residential wells, semi-annually fo-ve years. Three more upgradient wells will be installed after five years to track the trailing end of the plume as the concentration of the COC's decreases in existing upgradient wells. Thereafter, the existing and new monitor wells will be monitored annually for 25 additional years. Five year reviews are required under the NCP to determine if contaminants which remain onsite are causing additional risk to human health or the environment. As a result of this review, EPA will determine if additional site remediation is required. Five-year reviews are assumed to be conducted for a 30-year period. ALTERNATIVE 3: REDUCTION OF GROUNDWATER EXPOSURE AND MONITORED NATURAL ATTENUATION Capital Costs: PW O&M Costs: Total PW Costs: Duration to Achieve Cleanup: $1,914,650 $3,000.471 $3,873,299 7 Years Under this alternative, all homes, churches, and businesses in the Davis Park Road TCE Site area not currently connected to the City of Gastonia public water supply would be connected. In addition, residents will also be given the option to obtain wellhead treatment of their private well. This alternative also includes monitoring of groundwater from approximately 18 wells on a quarterly basis for 3 years. As in Alternative 2, three additional monitor wells will need to be installed. After installation, all existing 18 monitor wells and the three new wells will continue to be sampled on an annual basis for the next 27 years. In concert with the groundwater sampling, a Natural Attenuation study will be conducted on the bedrock aquifer plume. Natural Attenuation makes use of natural processes to contain the spread of contamination or to reduce the concentration and amount of pollutants at contaminated Sites. This means that contaminants are left in place while natural attenuation works on them. Much of the data required for the natural attenuation study has already been collected during the RI, however, additional data are needed. This data includes groundwater geochemical data, hydrogeologic parameters, and other necessary information to prove that the bedrock aquifer contaminant plume is in fact naturally attenuating. Site-specific data collected d. the RI were compiled and used as input into a groundwater model called BIOSCREEN, which is a screening model that simulates remediation of a groundwater contaminant plume through natural attenuation. The model predicted that the contaminant levels in the bedrock aquifer plume will be below EPA Drinking Water Standards within seven years from the present time. The groundwater contaminant plume appears to be flushing to Blackwood Creek, and the contaminants are evaporating in the Surface Water. Since groundwater contamination will not be actively remediated, this alternative also requires a five-year review. ALTERNATIVE 4: REDUCTION OF GROUNDWATER EXPOSURE AND GROUNDWATER TREATMENT Capital Costs: $2,879,874 PW O&M Costs: $7,014,434 Total PW Costs: $9,894,308 Duration to Achieve Cleanup: 10 Years This alternative includes all the provisions for prevention of exposure of current residents to contaminated groundwater described in Alternative 3, plus adds active remejiation of the groundwater that contains contaminant concentrations above the remediation goals. The major components of the groundwater treatment option include in-well vapor stripping. The in-well VOC removal system volatilizes VOCs contained in groundwater and removes them as a vapor. The vapor is then treated above ground by activated carbon. At the same time, air-lift pumping circulates the groundwater, which becomes cleaner with each pass through the in-well air stripper. It is projected that at least three air-stripper wells would be installed to treat the contaminated bedrock aquifer plume. The groundwater treatment is expected to last approximately 10 years. Groundwater monitoring will be conducted semi-annually for the first five years and annually for the next 25 years. AL TERNA TIV.REDUCTION OF GROUNDWATER EXPOSURE AND GROUNDWATER PUMP AND TREAT Capital Costs: $2,018,869 PW O&M Costs: $4,543,480 Total PW Costs: $6,562,349 Duration to Achieve Cleanup: 1 O Years This alternative includes all the provisions for prevention of exposure of current residents to contaminated groundwater described in Alternative 3, plus adds active remediation of the groundwater that contains contaminant concentrations above the remediation goals. The major component of this system is the installation of extraction wells into the targeted aquifer, which in this case would be the bedrock aquifer. It is estimated that three wells will need to be installed into the contaminated zone. Once the wells are completed, a submersible pump is installed in the well. The pump is used to feed the groundwater to an above-ground treatment system. The groundwater will be treated using activated carbon to remove VOC contaminants. The treated water is then discharged to an acceptable location, either a public-owned wastewater system or to a nearby stream. The groundwater treatment is expected to last approximately 10 years. Groundwater monitoring will be conducted semi-annually for the first five years and annually for the next 25 years. CRITERIA FOR EVALUATING REMEDIAL ALTERNATIVES The selection of the preferred alternative for the Davis Park Road Site, as described in this Proposed Plan, is the result of a comprehensive screening and evaluation process. The Feasibility Study identified and analyzed appropriate alternatives for addressing the contamination at the Site. The Feasibility Study and other documents describe, in detail, the alternatives considered, as well as the process and criteria EPA used to narrow the list of the potential remedial alternatives to address the contamination at the Site. As stated previously, all of these documents are available for public review in the Information Repository/ Administrative Record. documents are available for pie review in the Information Repository/ Administrative Record. EPA always uses the following nine criteria to evaluate alternatives identified in the Feasibility Study. The remedial alternative selected for a Superfund site must achieve the two threshold criteria as well as attain the best balance among the five evaluation criteria. EPA's Proposed Alternative may be altered or changed based on the two modifying criteria. The nine criteria are as follows: THRESHOLD CRITERIA 1. Overall protection of human health and the environment: The degree to which each alternative eliminates, reduces, or controls threats to public health and the environment through treatment, engineering methods or institutional controls. 2. Compliance With Applicable or Relevant and Appropriate Requirements (ARARs): The alternatives are evaluated for compliance with all state and federal environmental and public health laws and requirements that apply or are relevant and appropriate to the site conditions. EVALUATING CRITERIA 3. Cost: The benefits of implementing a particular remedial alternative are weighed against the cost of implementation. Costs include the capital (up-front) cost of implementing an alternative over the long term, and the net present worth of both capital and operation and maintenance costs. 4. Implementability: EPA considers the . technical feasibility (e.g., how difficult the alternative is to construct and operate) and administrative ease (e.g., the amount of coordination with other government agencies that is needed) of a remedy, including the availability of necessary materials and services. 5. 6. Short-term etftiveness: The length of time needed to implement each alternative is considered, and EPA assesses the risks that may be posed to workers and nearby residents during construction and implementation. Long-term effectiveness: The alternatives are evaluated based on their ability to maintain reliable protection of public health and the environment over time once the cleanup goals have been met. 7. Reduction of contaminant toxicity. mobility, and volume: EPA evaluates each alternative based on how it reduces (1) the harmful nature of the contaminants, (2) their ability to move through the environment, and (3) the volume or amount of contamination at the site. MODIFYING CRITERIA 8. State acceptance: EPA requests state comments on the Remedial Investigation and Feasibility Study reports, as well as the Proposed Plan, and must take into rnnsideration whether t!ie state concurs with, opposes. or has no comment on EPA's preferred alternative. 9. Community acceptance: To ensure that the public has an adequate opportunity to provide input, EPA holds a public comment period and considers and responds to all comments received from the community prior to the final selection of a remedial action. • • EVALUATION OF ALTERNATIVES This Table profiles the performance of the alternatives in terms of these evaluation criteria noting how it compares to the other alternatives under consideration (State and Public Acceptance were not rated). The numerical ranking is a relative relationship, on a scale of 0-5, of each alternatives performance under each criteria. 1-No Action 2-Limited 3-Reduction of GW 4-Reduction of 5-Reduction of Action Exposure.& GW Exposure & GW Exposure & Monitored Natural Treatment w/ Pump and Treat Attenuation air strippina Overall Protection 0 1 4 5 5 Compliance w/ ARARS 0 0 4 5 5 Long-Term Effectiveness 0 1 4 5 5 Reduction ofT/MN 0 0 5 5 5 Short-Term Effectiveness 5 4 3 3 3 Implementability 5 4 3 3 3 Present Worth Costs $140,055 $990,225 $3,873,299 $9,894,308 $6,562,349 EPA'S PREFERRED ALTE.TIVE • As discussed in the introduction, EPA is proposing to issue a contingency Record of Decision. After conducting a detailed analysis of all the feasible cleanup alternatives based on the criteria described in the previous sections, EPA is proposing the following cleanup plan to address groundwater contamination at the Site. The EPA preferred alternative is: ALTERNATIVE 3-GROUNDWATER EXPOSURE REDUCTION AND MONITORED NATURAL ATTENUATION COST: $3,873,299 Based on current information, this alternatives appears to provide the best balance of trade-offs with respect to the nine criteria that EPA uses to evaluate alternatives. This alternative is expected to achieve the Remedial Action Objectives within a reasonable amount of time and is cost effective. EPA believes the preferred alternative will satisfy the statutory requirements of Section 121 (b) of CERCLA, 42 USC 9621 (b), which provides that the selected alternative be protective of human health and the environment, comply with ARARs, be cost effective, and utilize permanent solutions and treatments to the maximum extent practicable. The selection of the above alternatives is preliminary and could change in response to public comments. As this alternative relies on monitored natural attenuation to clean the groundwater, the EPA will be required to substantiate that natural degradation is occurring, and continue to verify that natural attenuation continues to occur. The frequency of this monitoring will be established in the Remedial Design. In the event that data collected cannot substantiate the occurrence of natural attenuation, a contingency remedy, Alternative 5, will be implemented. ALTERNATIVE 5 -GROUNDWATER EXPOSURE ABATEMENT AND GROUNDWATER PUMP AND TREAT Cost: $6,562,349 It is anticipated that this decision will be made within three years of the signing of the Record of Decision. • • COMMUNITY PARTICIPATION EPA has developed a community relations program as mandated by Congress under Superfund to respond to citizen's concerns and needs for information, and to enable residents and public officials to participate in the decision-making process. Public involvement activities undertaken at Superfund sites consist of interviews with local residents and elected officials, a community relations plan for each site, fact sheets, availability sessions, public meetings, public comment periods, newspaper advertisements, site visits, and any other actions needed to keep the community informed and involved. EPA is conducting a 30-day public comment period from July 27, 1998 to August 26, 1998, to provide an opportunity for public involvement in selecting the final cleanup method for this Site. Public input on all alternatives, and on the information that supports the alternatives is an important contribution to the remedy selection process. During this comment period, the public is invited to attend a public meeting on July 28, 1998, at the Taylor Memorial Baptist Church, at which EPA will present the Remedial Investigation/ Feasibility Study and Proposed Plan describing the preferred remedial alternative for the Davis Park Road site and to answer any questions. Because this Proposed Plan Fact Sheet provides only a summary description of the cleanup alternatives being considered, the public is encouraged to consult the Information Repository for a more detailed explanation. During this 30-day comment period, the public is invited to review all site-related documents housed at the Information Repository located at Gaston County Public Library, 1555 E, Garrison Boulevard, Gastonia, N.C., and offer comments to EPA either orally at the public meeting or in written form during this time period. The actual remedial action could be different from the preferred alternative, depending upon new information or statements EPA may receive as a result of public comments. If you prefer to submit written comments, please mail them postmarked no later than midnight August 24th to: Diane Barrett NC Community Involvement Coordinator U.S.E.P.A., Region 4 North Site Management Branch 61 Forsyth Street, SW Atlanta, GA 30303-3014 All comments will be reviewed and a response prepared in making the final determination of the most appropriate alternative for cleanup/treatment of the Site. EPA's final choice of a remedy will be issued in a Record of Decision (ROD). A document called a Responsiveness Summary summarizing EPA's response to all public comments will also be issued with the ROD. Once the ROD is signed by the Regional Administrator it will become part of the Administrative Record (located at the Library) which contains all documents used by EPA in making a final determination of the best cleanup/treatment for the Site. Once the ROD has been approved, EPA will begin the design of the selected remedy. _____ ___,a.,_ ________ , _______ _ INFORMATION REPOSITORY LOCATION: Business Hours: Gaston County Public Library 1555 E .. Garrison Boulevard Gastonia, NC 28054 Phone: (704) 868-2167 Monday-Thursday 9:00 am -9:00 pm Friday & Saturday 9:00 am -6:00 pm During Scflool Sunday 2:00 pm -6:00 pm During Summer -Closed on Sunday FOR MORE INFORMATION ABOUT SITE ACTIVITIES, PLEASE CONTACT: Ms. Jennifer Wendel, Remedial Project Manager or Ms. Diane Barrett, NC Community Involvement Coordinator North Site Management Branch Waste Management Division U.S. Environmental Protection Agency, Region IV 61 Forsyth Street, SW Atlanta, Georgia 30303-3104 Toll Free No.: 1-800-435-9233 MAILING LIST If you are not already on our mailing list and would like to be placed on the list to receive future information on the Davis Park Road Site, or if you want your name removed from the list, or if you have a change of address, please complete this form and return to Diane Barrett, Community Involvement Coordinator at the above address: NAME: ADDRESS:--------------------------- CITY, STATE, ZIP COu..i::.. ______________________ _ PHONENUMBE~·------------------------ Addition □ Change of Address □ Deletion □ GLOSS. OF TERMS USED IN THIS FAC.HEET Aquifer: An underground geological formation, or group of formations, containing usable amounts of groundwater that can supply wells and springs. Administrative Record: A file which is maintained and contains all information used by the lead agency to make its decision on the selection of a method to be utilized to clean up/treat contamination at a Superfund site. This file is held in the information repository for public review. Applicable or Relevant and Appropriate Requirements (ARARs): The federal and state requirements thafa selected remedy must attain. These requirements may vary among sites and various alternatives. Baseline Risk Assessment: A means of estimating the amount of damage a Superfund site could cause to human heath and the environment. Objectives of a risk assessment are to: help determine the need for action; help determine the levels of chemicals that can remain on the site after cleanup and still protect health and the environment; and provide a basis for comparing different cleanup methods. Carcinogen: Any substance that can cause or contribute to the production of cancer; cancer-producing. Comprehensive Environmental Response, Compensation and Liability Act (CERCLA): A federal law passed in 1980 and modified in 1986 by the Superfund Amendments and Reauthorization Act (SARA). The Acts created a special tax paid by producers of various chemicals and oil products that goes into a Trust Fund, commonly known as Superfund. These Acts give EPA the authority to investigate and clean up abandoned or uncontrolled hazardous waste sites utilizing money from the Superfund Trust or by taking legal action to force parties responsible for the contamination to pay for and clean up the site. 1,2 DCE: An abbreviation for 1,2-Dichloroethene, a Site Contaminant of Concern. Feasibility Study Refor to Remedial Investigation/Feasibility Study. Groundwater: Water found beneath the earth's surface that fills pores between materials such as sand, soil, or gravel (usually in aquifers) which is often used for supplying wells and springs. Because groundwater is a major source of drinking water there is growing concern over areas where agricultural and industrial pollutants or substances are getting into groundwater. Hazardous Ranking System (HRS): The principle screening tool used by EPA to evaluate risks to public health and the environment associated with hazardous waste sites. The HRS calculates a score based on the potential of hazardous substances spreading from the site through the air, surface water, or groundwater and on other factors such as nearby population. This score is the primary factor in deciding if the site should be on the National Priorities List a~d, if so, what ranking it should have compared to other sites on the list. Information Repository: A file containing accurate up-to-date information, technical reports, reference documents, information about the Technical Assistance Grant, and any other materials pertinent to the site. This file is usually located in a public building such as a library, city hall or school, that is accessible for local residents. NCDENR: An abbreviation for the North Carolina Department of Environment and Natural Resources. MTBE: An abbreviation for Methyl-tert-butyl ether, a Site Contaminant of Concern. National Priorities List (NPL): EPA's list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial action under Superfund. A site must be on the NPL to receive money from the Trust Fund for remedial action. The list is based primarily on the score a site receives from the Hazard Rankl System (HRS). EPA is required to ulte the NPL at least once a year. Part per Billion: This term describes one part of a contaminant in one billion parts of a media. It is roughly equivalent to dropping an aspirin tablet into a swimming pool. PCE: An abbreviation for Tetrachloroethene, a site Contaminant of Concern. Plume: A term used to describe the aerial extent of contamination in groundwater. Remedial Action Objectives: These are specific objectives which are identified to protect both human health and the environment that take into consideration the environmental media contaminated (i.e., groundwater, soil, surface water, sediment, or air) and the contaminants present in each medium. The main goal of the objectives is to prevent exposure to contaminants in groundwater, soil, surface water, sediment, or air in excess of risk-based human health or environmental standards. Remedial Investigation/Feasibility Study (RIIFS): The Remedial Investigation is an in-depth, extensive sampling and analytical study to gather data necessary to determine the nature and extent of contamination at a Superfund site; to establish criteria for cleaning up the she; a description and analysis of the potential cleanup alternatives for remedial actions; and support the technical and cost analyses of the alternatives. The Feasibility study also usually recommends selection of a cost-effective alternative. Record of Decision (ROD): A public document that announces and explains which method has been selected by the Agency to be used at a Superfund site to clean up the contamination. Responsiveness Summary: A summary of oral and written public comments received by EPA during a public comment period and EPA's responses to those comments. The responsiveness summary is a key part of the Reco,-d of Decision. TCE: An abbreviation for Trichloroethene, a Site Contaminant of Concern. Volatile Organic Compounds (VOCS): Any organic compound that evaporates readily into the air at room temperature. Water Table: The level below which the soil or rock is saturated with water, sometimes referred to as the upper surface of the saturated zone. The level of groundwater. • U.S. Environmental Protection Agency 61 Forsyth Street, SW Atlanta, Georgia 30303-3014 • North Site Management Branch Diane Barrett, Community Involvement Coord.,.~-u.s-,/~t~}gJ;*;i.-::~~~~~: __ Jennifer Wendel, Remedial Project Manager /4"' \.-l'"?\ ! "°'"·" ;.',; -----------------------------!"\~,-J~U,!"L!'!°J°!'!~u'!"'""";!""'"~, ,'!!'.,~,vA~TF!". !"LJ~U!'!,"", ~J~·,'( Official Business ! uSi::~:;oo ,v -;,tr Penalty for Private Use $300 ~ .... ~/ i_ ____ t·-l ;;;i;~~"J ___ _j Region 4 ----,. -· -----OAVS004B I --- 1SfF IC AFFAIRS T 01i I HARRY ZINN, pUBLN SOLID WASTE MGM I \I suPERFUND s~t:i~o~MENT, HEALTH I NC OEPT oFL RESOURCES \ I " NATURA I : p.O• BOX 21681 NC 21611-1681 . ) I RALEIGH \__ • United States Environmental Protection Agency • Office of Solid Waste and Emergency Response (5102G) EPA 542-F-96-015 October 1996 &EPA A Citizen's Guide to Natural Attenuation Technology Innovation Office What is natural attenuation? Natural attenuation makes use of natural processes to contain the spread of contamination from chemical spills and reduce the concentration and amount of pollutants at contaminated sites. Natural attenua- tion-also referred to as intrinsic remediation, bioallenuation, or intrinsic bioremediation-is an in situ treatment method. This means that environmen- tal contaminants are left in place while natural at- tenuation works on them. Natural attenuation is · often used as one part·of a site cleanup that also includes the control or removal of the source of the contamination. How does natural attenuation work? The processes contributing to natural attenuation are typically acting at many sites, but at varying rates and degrees of effectiveness, depending on the types of contaminants present, and the physical, chemical and biological characteristics of the soil and ground water. Natural attenuation processes are often cat- egorized as destructive or non-destructive. Destruc- tive processes destroy the contaminant. Non-destructive processes do not destroy the con- taminant but cause a reduction in contaminant concentrations. Technology Fact Sheet Natural attenuation processes may reduce contami- nant mass (through destructive processes such as bio- degradation and chemical transformations); reduce contaminant concentrations (through simple dilution or dispersion); or bind contaminants to soil particles so the contamination does not spread or migrate very far (adsorption). Biodegradation, also called bioremediation, is a pro- cess in which naturally occurring microorganisms (yeast, fungi, or bacteria) break down, or degrade, hazardous substances into less toxic or nontoxic sub- stances. Microorganisms, like humans, eat and digest organic substances for nutrition and energy. (In chemical terms, "organic" compounds are those that contain carbon and hydrogen atoms.) Certain micro- organisms can digest organic substances such as fuels or solvents that are hazardous to humans. Biodegra- dation can occur in the presence of oxygen (aerobic conditions) or without oxygen (anaerobic condi- tions). In most subsurface environments, both aerobic and anaerobic biodegradation of contaminants occur. The microorganisms break down the organic con- taminants into harmless products-mainly carbon di- oxide and water in the case of aerobic biodegradation (Figure I). Once the contaminants are degraded, the A Quick Look at Natural Attenuation Uses naturally occurring environmental processes to clean up sites. Is non-invasive and allows the site to be put to productive use while being deaned up. Requires careful study of site conditions and monitoring of contaminant levels. .C· t,• Printed on Recycled Paper • • Figure 1. Schematic Diagram of Aerobic Blodegradation In Soll microorganism populations decline because they have used their food sources. Dead microorganisms or small populations in the absence of food pose no contamination risk. The fact sheet entitled A Citizen's Guide to Bioremediation describes the process in detail (see page 4). Many organic contaminants, like petroleum, can be biodegraded by microorganisms in the underground environment. For example, biodegradation processes can effectively cleanse soil and ground water of hy- drocarbon fuels such as gasoline and the BTEX com- pounds-benzene, toluene, ethylbenzene, and xylenes. Biodegradation also can break down chlor- inated solvents, like trichloroethylene (TCE), in ground water but the processes involved are harder to predict and are effective at a smaller percentage of sites compared to petroleum-contaminated sites. Chlorinated solvents, widely used for degreasing air- craft engines, automobile parts, and electronic com- ponents, are among the most often-found organic ground-water contaminants. When chlorinated com- pounds are biodegraded, it is important that the deg- radation be complete, because some products of the breakdown process can be more toxic than the origi- nal compounds. The effects of dilution and dispersion appear to re- duce contaminant concentration but do not destroy the contaminant. Relatively clean water from the ground surface can seep underground to mix with and dilute contaminated ground water. Clean ground water from an underground location flowing into - 2 - contaminated areas, or the dispersion of pollutants as they spreading out away from the main path of the contaminated plume also lead to a reduced concen- tration of the con tarn in ant in a given area. Adsorption occurs when contaminants attach or sorb to underground particles. Fuel hydrocarbons tend to repel water, as most oily substances do. When they have an opportunity to escape from the ground water by attaching to organic matter and clay minerals that also repel water, they do so. This is beneficial because it may keep the contaminants from flowing to an area where they might be a health threat. Sorption, like dilution and dispersion, appears to reduce the concentration and mass of contam ina- tion in the ground water, but does not destroy the contaminants. Why consider natural attenuation? In certain situations, natural attenuation is an effec- tive, inexpensive cleanup option and the most appro- priate way to remediate some contamination problems. Natural attenuation is sometimes mislabeled as a "no action" approach. However, natural attenuation is really a proactive approach that focuses on the confirmation and monitoring of natu- ral remediation processes rather than relying totally on "engineered" technologies. Mobile and toxic fuel hydrocarbons, for example, are good candidates for natural attenuation. Not only are they difficult to trap because of their mobility, but they are also among the contaminants most easily destroyed by biodegra- dation. Natural attenuation is non-invasive, and, un- • like many elaborate mechanical site cleanup tech- niques, while natural attenuation is working below ground, the land surface above ground may continue to be used. Natural attenuation can be less costly than other active engineered treatment options, espe- cially those available for ground water, and requires no energy source or special equipment. Will natural attenuation work at every site? To estimate how well natural attenuation will work and how long it will take requires a detailed study of the contaminated site. The community and those con- ducting the cleanup need to know whether natural at- tenuation, or any proposed remedy, will reduce the contaminant concentrations in the soil and water to legally acceptable levels within a reasonable time. Natural attenuation may be an acceptable option for sites that have been through some active remediation which has reduced the concentrations of contami- nants. However, natural attenuation is not an appro- priate option at all sites. The rates of natural processes are typically slow. Long-term monitoring is necessary to demonstrate that contaminant concen- trations are continually decreasing at a rate sufficient to ensure that they will not become a health threat. If not, more aggressive remedial alternatives should be considered. What Is An Innovative Treatment Technology? Treatment technologies are processes applied to the treatment of hazardous waste or contaminated materials to permanently alter their condition through chemical, biological, or physical means. Innovative treatment technologies are those that have been tested, selected or used for treatment of hazardous waste or contaminated materials but lack well-documented cost and performance data under a variety of operating conditions. • Because the ability of natural attenuation to be an ef- fective cleanup method depends on a variety of con- ditions, the site needs to be well-characterized to determine if natural attenuation is occurring or will occur. Sites where the soil contains high levels of natural organic matter, such as swampy areas or former marshlands often provide successful condi- tions for natural attenuation. Certain geological for- mations such as fractured bedrock aquifers or limestone areas are less likely candidates for natural attenuation because these environments often have a wide variety of soil types that cause unpredictable ground water flow and make predicting the move- ment of contamination difficult. Where is natural attenuation being used? Natural attenuation is being used to clean up petro- leum contamination from leaking underground stor- age tanks across the country. Within the Superfund program, natural attenuation_ has been selected as one of the cleanup methods at 73 ground-water-contaminated sites-but is the sole treatment option at only six of these sites. Some of these sites include municipal and industrial land fills, refineries, and recyclers. At the Allied Signal Brake Systems Superfund site in St. Joseph, Michigan, microorganisms are effectively removing TCE and other chlorinated solvents from ground water. Scientists studied the underground movement of TCE-contaminated ground water from its origin at the Superfund site to where it entered Lake Michigan about half a mile away. At the site it- self, they measured TCE concentrations greater than 200,000 micrograms per liter (µg/L), but by the time the plume reached the shore of Lake Michigan, the TCE was one thousand times less-only 200 µg/L. About 300 feet offshore in Lake Michigan, the con- centrations were below EPA's allowable levels. EPA estimated the plume took about 20 years to move from the source of contamination to Lake Michi- gan-plenty of time for the microorganisms natu- rally present in the ground water to destroy the TCE without any outside intervention. In fact, microor- ganisms were destroying about 600 pounds of TCE a year at no cost to taxpayers. EPA determined that na- ture adequately remediated the TCE plume in St. Joseph. - 3 - • • For More lnfonnatlon The publications listed below can be ordered free of charge by faxing your request to NCEPI at 51~9-8695. If NCEPI is out of stock of a document, you may be directed to other sources. Some of the documents listed also can be downloaded free of charge from EPA's Cleanup Jnfcxmation (CLU-IN) Wortd Wide Web s~e (http://clu-in.com) or electronic bulletin board (301-589-8366). The CLU-IN help line number is 301-589-8368. You may write to NCEPI at National Center for Environmental Publications and Information (NCEPI) P.O. Box 42419 Cincinnati, OH 45242 A Citizen's Guide to Bioremediation, April 1996, EPA 542-F-96-007. Symposium on Intrinsic Bioremediation of Ground Water, August 1994, EPA 540.R-94-515. Bioremediation Research: Producing Low-Cost Tools to Reclaim Environments, September 1995, EPA 540-R-95- 523a. "Natural Bioremediation of TCE," Ground Water Currents (newsletter), September 1993, EPA 542-N-93-008. "Innovative Measures Distinguish Natural Bioattenuation from Dilution/Sorption," Ground Water Currents (newsletter), December 1992, EPA 542-N-92-006. How to Evaluate Alternative Cleanup Technologies for UST Sites, (Chapter on Natural Attenuation), May 1995, EPA 510-6-95-007. Bioremediation Resource Guide, September 1993, EPA 542-B-93-004. A bibliography of publications and other sources <if information about bioremediation technologies. Engineering Bulletin: In Situ Biodegradation Treatment, April 1994, EPA 540-S-94-502. Selected Alternative and Innovative Treatment Technologies for Corrective Action and Site Remediation: A Bibliography of EPA Information Sources, January 1995, EPA 542-B-95-001. A bibliography of EPA publications about Innovative treatment technologies. WASTECH" Monograph on Bioremediation, ISBN #1-883767-01-6. Available for $49.95 from the American Academy of Environmental Engineers, 130 Holiday Court, Annapolis, MD 21401. Telephone 410.266-3311. NOTICE: This fact sheet is intended solefy as general guidance and inlonnation. ft is not intended, nor can it be retied upon. to create any n·ghts enforceable by any paftt in litiQation w;th the United States. The Agency also reserves the right to change this guidance at any time without public notice. - 4 - ■■-··-,, lf_ ··--··----· ... • Meeting Notice RECEIVED JUL 16 1998 SUPERFUNO SECTION The Environmental Protection Agency will conduct a Proposed Plan public meeting on July 2rfh beginning at 7:00PM in the auditorium of the Taylor Memorial Baptist Church 2616 Davis Park Road Gastonia, N. C. to present the results of the Remedial Investigation and possible cleanup/treatment options available for the Davis Park Road TCE Site. The Proposed Plan fact sheet providing this information will be mailed on July 2:J"d to citizens on the Site's mailing list. The public comment period starts on July 27 and ends August 26, 1998. If you have any questions in the meantime, please contact Diane Barrett, EPA Community Involvement Coordinator at 1-800-435-9233. ' . it· Region 4 • U.S. Environmental Protection Agency 61 Forsyth Street, SW Atlanta, Georgia 30303-3014 '' ' ~ U.S. OFFlC!,'\L fUHt. North Site Management Bra_n~n . · ·• -"~ us ?osr.sc;s Diane Barrett, Communityl=lelations ·coordt~NAc'• * Jennifer Wendel, Remedial ProjectfMan'agera;,re O 0,3 2 Y< \ j I uSc$3CO * )fficial Business 1enalty for Private Use $300 S/F ·-. DPRD0066 --, MR. WILLIAM MEYER, DIRECTOR I SOLID WASTE MANAGEMENT DIVISION i NC DEPT. OF ENVIRONMENT, HEALTH 1 & NATURAL RESOURCES , P.O. BOX 27687 .I I RALEIGH NC 27611-7687 I \ -·---------------- 276i i---7087