United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R04-92/118
September 1992
&EPA Superfund
Record of Decision:
US DOE Oak Ridge
Reservation (Operable Unit 6),
TN
-------
NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement but adds no further applicable information to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
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50272-101
REPORT DOCUMENTATION i. REPORT NO. 2,
PAGE EPA/ROD/R04-92/118
4. TWttndSuMHW
SUPERFUND RECORD OF DECISION
USDOE Oak Ridge Reservation (Operable Unit 6) , TN
Fourth Remedial Action - Interim
7. Author<«)
9. PMfoimlng Org»I nlatfon Name ind Addrtu
12. Sponsoring Organtotlon Nnm and Addrau
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
3. ftedptonf* Accoulon No.
5. Report Date
09/30/92 -
6.
8. Performing OrganlaUon Rapt No.
10. ProiecVTuk/Work UnH No.
11. Contnct(C)orar*nt(G)No.
(C)
(G)
i3> Typv o> Report • PMIOQ Covorod*
800/000
14.
IS. Supptomentwy Noln
PB93-964025
16. AtMtrKt(UinH: 200 word*)
The Oak Ridge Reservation (USDOE)(OU6) site is located within the K-25 plant, a former
uranium enrichment facility in Oak Ridge, Roane County, Tennessee. Land use in the
area is mixed industrial, recreational, residential, and agricultural. Since the
1940's, the fabrication, decontamination, and maintenance processes associated with
activities at the site, known as K-25, have produced hazardous and radioactive wastes.
To dispose of these wastes, treatment, storage, and disposal facilities were
constructed at the K-25 site. In the mid-1970's, the swampy spring discharge area at
the base of one of the waste disposal units, the K-1070-C/D Burial Grounds, was filled
and a pipe was inserted into the hillside to collect natural seepage for routing to a
storm drain. The pipe discharge is referred to as SW31. In 1989, K-25 was divided
into OUs to address and isolate environmental problems into more manageable entities,
and the K-1070-C/D Burial Ground and SW31 became part of the K-1070 OU. The K-1070 OU
is presently undergoing an RI under CERCLA; however, SW31 has been isolated for interim
action. This ROD addresses an interim remedy to reduce the migration of contaminants
(See Attached Page)
17. Documnt Aratytte *. D»tcriptot»
Record of Decision - USDOE Oak Ridge Reservation (Operable Unit 6) , TN
Fourth Remedial Action - Interim
Contaminated Medium: sw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes), other organics
PCBs>' metals (lead)
(PAHs,
G. COSATI FMoVOroup
18. AnltabMty SMMixnt
19. Security CUM (IN* Report)
None
20. Security OM* (TM* Pig*)
None
21. NaotPigM
52
22. Mo*
(See ANSU39.18)
Stf Awtruetfoiw on Rt
OPTIONAL FORM 272 (4-77)
(Formrty NT1S4S)
DifMftniifit of Coimnor co
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EPA/ROD/R04-92/214
USDOE Oak Ridge Reservation (Operable Unit 6), TN
Fourth Remedial Action - Interim
Abstract (Continued)
and degradation of the environment caused by the SW31 discharge while the investigation
of the K-1070 OU continues. The objective of this ROD, which addresses OU6, is to
terminate the direct discharge of contaminants to surface water by intercepting and
routing contaminated waters for treatment via an NPDES-permitted outfall prior to
discharge to surface water. Future RODs will address source control actions to remediate
the K-1070-C/D disposal pits and trenches, which are suspected of causing releases of
hazardous substances to ground water and a final remediation action to address ground
water contamination problems at the K-25 site as a whole. The primary contaminants of
concern affecting the surface water are VOCs, including benzene, PCE, TCE, toluene, and
xylenes; other organics, including PCBs and PAHs; and metals, including lead.
The selected remedial action for this site includes collecting and pretreating surface
water using oxidation, pH adjustment, and flocculation/clarification to remove heavy
metals, followed by treatment by an air stripper to remove VOCs, and carbon polishing to
remove PCBs; .discharging the water offsite to a NPDES-permitted facility for final
treatment prior to discharge; controlling air emissions from the air stripping process
using carbon adsorption, if necessary, with regeneration or disposal of the spent carbon;
and conducting quarterly surface water monitoring. The estimated capital cost for this
remedial action is $350,000, with an annual O&M cost of $117,700.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific surface water clean-up goals are based on SDWA MCLs and primary health
advisory. These include benzene 0.005 mg/1; PCE 0.005 mg/1; TCE 0.005 mg/1; toluene
1 mg/1; xylenes (total) 10 mg/1; naphthalene 0.13 mg/1; and lead 0.05 mg/1.
-------
'•'•: ;;3£is$s*iiJai^^
*»»^^
DOE/OR-1050&D2
Interim Record of Decision
for the
Oak Ridge K-25 Site
K-1070 Operable Unit SW31 Spring
September 1992
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DOE/OR-1050&D2
92-225-161-62
Interim Record of Decision
for the
Oak Ridge K-25 Site
K-1070 Operable Unit SW31 Spring
September 1992
Prepared for
U.S. Department of Energy
under contract DE-AC05-90OR21851
Prepared by
Radian Corporation
120 South Jefferson Circle
Oak Ridge, Tennessee 37830
Doe. ID920803.2JM51
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CONTENTS
TABLES AND FIGURES . v
ACRONYMS AND INTTIALISMS vl
PART 1. DECLARATION 1-1
SITE NAME AND LOCATION 1-3
STATEMENT OF BASIS AND PURPOSE 1-3
ASSESSMENT OF THE SITE 1-3
DESCRIPTION OF SELECTED REMEDY 1-3
STATUTORY DETERMINATION 1-4
APPROVALS 1-5
PART 2. DECISION SUMMARY 2-1
SITE NAME, LOCATION. AND DESCRIPTION 2-3
Site Identification 2-3
Description 2:3
General Background 2-6
SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-6
HIGHLIGHTS OF COMMUNITY PARTICIPATION 2-7
SCOPE AND ROLE OF RESPONSE ACTION 2-8
SITE CHARACTERISTICS 2-8
SUMMARY OF SITE RISKS 2-10
DESCRIPTION OF ALTERNATIVES 2-15
Alternative 1, No Action 2-16
Alternative 2, Carbon Adsorption 2-16
Alternative 3, Air Stripping and CNF Treatment 2-18
Alternative 4, Air Stripping and Direct Discharge 2-20
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES . . . 2-21
Decision Matrix 2-21
Overall Protection of Human Health and die Environment 2-21
Compliance with ARARs 2-21
Long-Term Effectiveness and Permanence 2-23
Reduction of Toxicity, Mobility, or Volume Through Treatment 2-24
Short-Tenn Effectiveness 2-24
Implementability 2-24
Cost 2-25
State Acceptance 2-25
Community Acceptance 2-25
in wnm
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THE SELECTED REMEDY 2-25
STATUTORY DETERMINATIONS 2-26
Protection of Human Health and the Environment 2-26
Compliance with ARARs 2-29
Cost Effectiveness 2-29
Use of Permanent Solutions and Treatment 2-29
Preference for Treatment 2-30
DOCUMENTATION OF SIGNIFICANT CHANGES 2-30
BIBLIOGRAPHY 2-30
PART 3. RESPONSIVENESS SUMMARY 3-1
Overview 3-3
Background on Community Involvement 3-3
Summary of Comments Received and Agency Responses 3-3
Remaining Concerns 3-5
IV OW17/92
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TABLES
2.1 Maximum VOC concentrations and MCLs for wastewater contaminants .. 2-9
2.2 Maximum SVOC concentration 2-9
2.3 Inorganic contaminants and MCLs 2-11
2.4 Human health risks associated with inhalation of VOCs from the K-1070
SW31 groundwater discharge for the sample collector 2-13
2.5 Human health risks associated with 'inhalation of VOCs from the K-1070
SW31 groundwater discharge for the plant employee 2-14
2.6 SW31 Leachate Stream: evaluation of alternatives for interim
remediation 2-22
2.7 Capital costs 2-28
2.8 Operation and maintenance costs 2-28
FIGURES
2.1 Locator map, ORR 2-4
2.2 Locator map, SW31 perennial spring 2-5
2.3 Selected treatment system for SW31 2-27
OW17/K
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ACRONYMS AND INITIALISMS
ARAR applicable or relevant and appropriate requirement
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
CNF Central Neutralization Facility
DOE U.S. Department of Energy
EPA U.S. Environmental Protection Agency
FR Federal Register
IROD Interim Record of Decision
MCL maximum contaminant level
MTF Memorandum-To-File
NCP National Contingency Plan
NEPA National Environmental Policy Act
NPDES National Pollutant Discharge Elimination System
ORR Oak Ridge Reservation
OU operable unit
PCB polychlorinated biphenyl
R&D research and development
RCRA Resource Conservation and Recovery Act
SARA Superfund Amendments and Reauthorization Act of 1986
SVOC semivolatile organic compound
TDEC Tennessee Department of Environment and Conservation
USC United States Code
VOC volatile organic compound
VI
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PARTI. DECLARATION
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SITE NAME AND LOCATION
SW31 Perennial Spring, also known as K-1070 C/D Leachate Stream
Oak Ridge Reservation (ORR)
K-25 Site [K-1070 Operable Unit (OU)]
Oak Ridge, Tennessee
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected interim remedial action for the SW31
Perennial Spring, which is part of the K-1070 OU of the U.S. Department of Energy (DOE) K-25
Site in Oak Ridge, Tennessee. This action was chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to the extent practicable,
the National Contingency Plan (NCP). This decision is based on the administrative record file
for mis site.
The state of Tennessee, after review of relevant documentation, concurs with the federal
agencies on the selected remedy.
ASSESSMENT OF THE SITE
If not addressed by implementing the interim response action selected in this Interim
Record of Decision (IROD), actual or threatened releases of hazardous m'bttafK*s from this site
may present an imminent and substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF SELECTED REMEDY
This interim action is the first step towards the remediation of the K-1070 OU, which
comprises a burial ground used for the disposal of hazardous and radiological waste. SW31
Perennial Spring collects surface seepage waters and groundwater. Its discharge is primarily
contaminated whit organic compounds.
1-3 OWIT/B2
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The selected remedy is to treat SW31 discharge as follows:
• discharge preconditioning for removal of fouling agents, followed by
• treatment with an air stripper, followed by
• carbon polishing, followed by
• final treatment of the stream through the Central Neutralization Facility (CNF)
of the K-25 Site [the CNF is a National Pollutant Discharge Elimination System
(NPDES)-pennitted facility].
Therefore, this interim action will collect and treat the SW31 spring discharge prior to release
of treated effluent to surface water via an NPDES-permitted outfall.
STATUTORY DETERMINATION
This interim action protects human health and the environment, complies with federal and
state applicable or relevant and appropriate requirements (ARARs) for its limited scope, and is
cost-effective. Although this interim action is not intended to satisfy fully the statutory mandate
for permanence and treatment to the maximum extent practical, it does utilize treatment in
furtherance of that mandate. However, it may not constitute the final remedy for the SW31
Perennial Spring, because K-1070 OU, of which SW31 is part, is currently at an early stage of
investigation under CERCLA, and mere is no information available now on long-term permanent
solutions for K-1070 OU and SW31. This action does not constitute the final remedy for the K-
1070 OU; thus, the statutory preference for remedies that employ treatment to reduce toxicity,
mobility, or volume as a principal element is but partially addressed in this remedy.
This remedy will result in hazardous substances remaining on site at the K-1070 Burial
Grounds above health-based levels. A review of the remedy will be conducted within 5 years
once the remedy becomes operational and functional. To this regard, a remedy becomes
operational and functional either 1 year after construction is complete or when the remedy is
determined by U.S. Environmental Protection Agency (EPA) and the state to be functioning
properly, whichever is earlier. The review will be conducted to ensure mat the remedy continues
to adequately protect human health and die environment while DOE continues to develop final
remedial alternatives for the site. Because this is an IROD, review of this site and this remedy
will continue as part of the development of the final remedy for SW31 Perennial Spring and in
the context of the remediation of K-1070 OU.
PMDKO.MMM 1-4 OW17/W
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APPROVALS
A
A I '
Manager Date
U.S. Department of Energy
Oak Ridge Field Office
Director, DOE Oversight Division * Date
State of Tennessee
Tennessee Department of Environment and Conservation
_
i Regional Administrator Date
U.S. Environmental Protection Agency, Region IV
D92M03.2JM31 1~S OW17/92
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PART 2. DECISION SUMMARY
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SITE NAME, LOCATION, AND DESCRIPTION
fit*
The SW31 Perennial Spring, also known as the K-1070-C/D Leachate Stream, is part of
the K-1070 OU located within the K-25 Site, a federal facility on the ORE. Owned by DOE and
managed by Martin Marietta Energy Systems, Inc., K-25 is in Roane County, 6 miles southwest
of the city of Oak Ridge hi East Tennessee (Fig. 2.1).
SW31 is a perennial spring located inside the perimeter fence of K-25 (Fig. 2.2). It
surfaces approximately 200 ft west of the K-1070-C/D Classified Burial Ground on the east side
of K-25. The stream is contaminated primarily with volatile organic compounds (VOCs). Heavy
metals have also been found hi the water, together with traces of polychlorinated biphenyls
(PCBs) and other agents, including minimal alpha and beta activity. The stream flow rate ranges
from 3 to 6 gal/min. It is currently discharged to a storm drain and eventually flows to Mitchell
Branch.
Description
Groundwater is believed to contribute at least pan of the stream flow to SW31. The
proximity of K-1070 C/D Classified Burial Ground (a groundwater mound recharged by meteoric
waters) and its position upstream of SW31 lend credibility to this assumption. Groundwater flow
at K-25 is dominated by relatively shallow, downgradient movement of meteoric recharge to
discharge areas along Poplar Creek and the Clinch River.
-.Geologic conditions hi the vicinity of K-25 are quite complex. Fracturing and jointing
of the bedrock provide die chief hydrogeologic mechanism for groundwater flow. There are 25
known groundwater wells within 1 mile of K-25, including wells installed at the Tennessee Valley
Authority Blair Road Station, the Blair Road Building at the intersection of Blair Road and
Highway 58, and neighboring private residences.
Access to the spring is restricted because of Its position inside the perimeter fence of
K-25. Admission past the fence is controlled, and all entrances are guarded. Potential risk to
the general population is reduced by these institutional controls.
An impact on natural resources from the SW31 spring is the contamination of surface
waters from the discharge into Mitchell Branch, which is the main surface water feature hi the
vicinity of SW31. Mitchell branch flows northwest to its confluence with Poplar Creek,
subsequently joining the Clinch River waterway.
2-3 «m«
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PRIMARY HIGHWAYS AND ROADS
•J DOE BOUNDARY - ORR
Map of the DOE Oak Ridge Rtwrvatioa
(JCMICT TVA QCOLOOCM. WnCV. IMS)
lUffioaal Location of Y-12, ORNL. and K-26 Plant Sitaa
(•ova. mourn mnatata. i»umicfc MM)
Fig. 2.1. Locator map, ORR.
2-4
0*1713
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1000*
K-1210
Fig. 2.2. Locator map, SW31 perennial spring.
2-5
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General Background
There are industrial, recreational, residential, and light agricultural areas surrounding
K-2S. Residential properties closest to K-25 are approximately 1.5 miles to the north on the
lower slope of Black Oak Ridge in the Poplar Creek/Sugar Grove Valley area. These
neighboring areas are lightly to moderately populated.
Climate in the Oak Ridge area is classified as humid subtropical. ORR weather patterns
are generally temperate with warm, humid summers and moderately cool winters. The mean
yearly temperature is ~57°F, and the mean annual precipitation in the region is 54 in. The
region enjoys one of the calmest wind regimes in the country; the average wind speed is
— 4.4 mph.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Oak Ridge K-25 Site was constructed during World War n to supply the uranium-
enriched material for the Manhattan Project. The fabrication, decontamination, and maintenance
processes associated with activities at the K-25 Site produced hazardous and radioactive wastes.
To dispose of these wastes, treatment, storage, and disposal facilities were constructed at the
K-25 Site. The K-1070-C/D Classified Burial Ground is one such facility comprising several
potential contaminant sources, including trenches, pits, diked drum storage areas, and a
mii'itwiancg storage yard.
A spring with perennial flow (SW31) is located west of and downhill from the
K-107Q-C/D Burial Grounds and is contaminated by organic chemicals. The source of the
* m the spring is thought to be wastes, including solvents and hazardous chemicals
placed in the disposal pits. In the mid-1970s, the swampy spring discharge area at the base of
the K-1070-C/D Burial Grounds was filled, and a pipe was inserted in the hillside to collect
natural seepage for routing to a storm drain. The pipe discharge became SW31.
Remediation of SW31 was initially planned under the authority of the Resource
Conservation and Recovery Act (RCRA), as amended by the Hazardous and Solid Waste
Amendments of 1984, within the broader framework of the remediation of the K-1070-C/D
Classified Burial Ground.
2-6 OW17/R
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During December 1989, the ORR was placed on CERCLA's National Priority List. In
response to this regulatory initiative, K-25 was divided into OUs to address and isolate
environmental problems into more manageable entities. The K-1070 C/D Burial Ground and
SW31 became part of the K-1070 OU.
The K-1070 OU is presently undergoing a Remedial Investigation under CERCLA. Data
collected during die current characterisation and during previous Mfipl'ng pointed out th>t SW31
was suited for interim action. Analysis of this data confirmed that the initiative was appropriate,
and the lead and support authorities agreed to start interim action for SW31.
An experimental bioremediation project was conducted at the site prior to the decision
for interim action. Because of the need for prompt remedial action ensuing from that decision,
h was decided to use more reliable and proven techniques to remediate SW31 rather man perfect
an experimental technology with uncertain performance. Consequently, die bioremediation
project was terminated for reasons not related to this ROD during early 1992.
Compliance with pending regulations had an important part in the decision for action.
The NPDES permit for the K-25 Site is presently being renewed; it will require compliance with
water quality standards for the various stormwater discharges at die she and will prohibit die
introduction of untreated sources into die stormwater system.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
During July 1992, the Proposed Plan for the Oak Ridge K-25 Site K-1070 OU SW31
Springyns released to die public. This document was made available bod» in die administrative
record file and at die information repository maintained by DOE at die Information Resource
Center, 106 Broadway, Oak Ridge, Tennessee.
The Notice of Availability for me Proposed Plan was published in die Oak Rldger — die
daily newspaper of Oak Ridge — on July 2, 1992. No public meeting was scheduled, but an
opportunity for a meeting was offered hi the Notice of Availability for die Proposed Plan. The
public comment period lasted for 30 days, from July 2 to July 31, 1992.
Although die public expressed no desire to bold a meeting, several comments on the
proposed plan were submitted. A response to die comments received during diis period is
included in die Responsiveness Summary, which is Part 3 of mis IROD.
2-7 own/n
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This decision document presents the selected remedial action for the SW31 Perennial
Spring at the DOE's K-25 Site in Roane County, next to the city of Oak Ridge, Tennessee,
chosen in accordance with CERCLA, as amended by SARA, and, to die extent practicable, NCP.
The decision for this site is based on the administrative record.
SCOPE AND ROLE OF RESPONSE ACTION
Remediation of the K-25 Site is a complex problem. Division of the site into OUs will
facilitate the clean-up process. The K-1070 OU has been identified as a high priority site in the
draft ORR Site Management Plan. Although the remedial investigation of the K-1070 OU is
ongoing, h was determined that it was appropriate to isolate SW31 for interim action. This
initiative is being undertaken to eliminate an identified and easily controllable release of
hazardous substances to Mitchell Branch. The goal of this interim action is to quickly reduce the
migration of contaminants and degradation of the environment while the investigation of the
K-1070 OU continues.
It is expected mat mis interim action will be followed by one or more interim or final
source control actions to remediate the K-1070-C/D disposal pits and trenches, which are
suspected of causing releases of hazardous substances to ground water. It is also likely that a final
remediation action to address groundwater contamination problems at the K-25 Site as a whole
will be required as K-25 Site remediation progresses.
SITE CHARACTERISTICS
SW31 is a perennial spring that surfaces about 200 ft west of the K-1070-C/D Classified
Burial Ground on the east side of K-25. The spring discharge is collected by a pipe inserted into
the base of a hill and is conveyed to a storm drain. The spring is contaminated by wastes
disposed of in trenches or pits excavated into the hill above the spring although the source of
contamination is not precisely identified. The principal threat posed by the contaminated spring
is degradation of surface water quality.
The SW31 spring waters contain significant concentrations of several VOCs, traces of
semivolatile organic compounds (SVOCs), PCBs, and various metals. The total discharge of
VOCs from the spring is about 2.4 Ib/d based on maximum measured concentrations. Maximum
concentrations of VOCs are presented in Table 2.1. The corresponding drinking water maximum
contaminant levels (MCLs), where available, are included for comparison. Table 2.2 lists SVOC
concentrations. Radiological contamination is minimal: gross a radiation has been measured at
MnOUMM 2-8 OW17/V2
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Table 2.1. Maximum VOC concentrations and MCLs for wastewater contaminant!
Compound
Benzene
1,1-Dicbloroetbane
Metbykne diloride
Toluene
Trans- 1 ,2-dichloroetheoe
1.1,1-Tiicbloroetbaiie
,-...__..
Tncblocoethene
Btbylbenzene
1,1-Dichloroethene
Xylene (total)
Carbon tetrachloride
Vinyl diloride
1,1,2-TricUoroetbane
Hexachloroethane
Tetnchloroethene
Maximum concentration
(mg/L)
1.3
3.8
8.0
3.1
1.0
11.0
0.7
0.43
1.0
1.9
0.25
0.5
0.023
0.005
0.11
MCL
(mg/L)
0.005*
.
0.005*
1-
0.1-
0.2-
0.005-
0.7-
0.007 (MAX
10-
0.005*
0.002*
0.006*
0.001 (MAX
0.005*
•40 CPR 141.61, July 1,1991
•55 PR 145, July 27,1990
*HA tadieatM primary health advisory, not MCL.
Table 2 J. Maximum SVOC concentration
Di-o-butbyl pbtbalate
Nartfaaicne
"•fr***^1**" ***
Bu-2-etfayuexyl phtbalate
Di-n-octyl pbtbalate
Maximum
concentration
(mg/L)
0.004
0.13
0.004
0.011
MCL
(mg/L)
4*
0.02 (HA/
0.003*
W
•55 Fedml Register (FR) 145. July 27,1990.
•HA indicatCT primary health advisory, not MCL.
2-9
0*17*2
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5 pCl/L (MCL is IS pCi/L), and gross 0 radiation at 8 pCi/L (MCL is 4 mrem/year, screening
level threshold of concern is 30 pCi/L).
Iron is die main inorganic contaminant at a maximum concentration of 41 mg/L.
Manganese is also found at a concentration of 13 mg/L. Bom of these metals exceed the draft
NPDES permit water quality limits; they also present an operational concern (fouling) for most
discharge treatment operations. Table 2.3 presents the inorganic contaminant of concern at
SW31.
The leachate stream data compiled from available sources represent maximum
contaminant concentrations. All VOCs, SVOCs, and metals exceeding the MCL or the primary
health advisory level are listed as well as all concentrations relevant to process design. Total
PCBs have been measured up to approximately 0.005 mg/L. The stream's radioactivity is below
the limits established for drinking water.
Routes of exposure to the public presently are limited by institutional controls because
SW31 is inside the perimeter fence of K-25. Therefore, only the current plant employees and
tfch^fciJ personnel involved in environmental activities like sampling are exposed to the
contaminated water. On the other hand, the stream is discharged to a storm drain and eventually
to the surface water system. This constitutes a potential hazard to the environment.
SUMMARY OF SITE RISKS
Risk assessment for interim action examines the threat to human health and the
environment posed by site contamination both in terms of potential carcinogenic effects and
noncarcinogenic toxicity. EPA guidance states that the risk assessment performed in support of
interim remediation may be qualitative if insufficient data exist to quantify the risk. Conditions
analyzed are those existing in the absence of any remediation. Risk to human health is expressed
hi terms of excess cancer risk or hi terms of reference dose thresholds. In accordance with NCP
requirements, ecological risk for nonhuman receptors was also addressed.
The only medium of concern for this interim action is contaminated surface water (spring
discharge). In the following screening level risk assessment, only potential receptors based on
current conditions were considered. Consequently, risk from exposure to the metals or the low
concentration of PCBs hi SW31 has not been quantified for human receptors because there are
no complete pathways of exposure under baseline conditions; this will be discussed later.
2-10 0*17/92
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Table 2.3. Inorganic contaminants and MCLs
Compound
f trimium
Iron
Manganese
Silver
iSflfnivir
Calcium
Lead
Kfftffiwtftitini
Molybdenum
PH
Total dissolved solids
Alkalinity
Hardness
Total suspended solids
Maximum
concentration
(mg/L)
0.005
41.0
13.7
0.133
0.06
100
0.041
15.0
0.145
6.3 - 7.3
498
301
321
51
MCL
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Risk to human health was determined on the basis of the maximum detected concentration
for benzene, bis(2-ethylexyl)phthalate, 1,1-dichloroethane, ethylbenzene, hexachloroethane,
methylene chloride, tetrachloroethene, toluene, 1,1,1-trichloroethane, 1,1,2-trichloroethane,
trichloroethylene, vinyl chloride, and xylene. Certain data relevant to risk assessment was
unavailable for some of the target contaminants, and health risks could not be derived.
Risk to human health from exposure to contaminated water was evaluated for the only
two receptors under worst-case current conditions—a professional sampler who collects water
samples for analysis and a general plant worker standing 10 m away from SW31 for 8 h/d, 5
d/week. Risk for mis worker would represent a conservative upper-bound risk for the occupants
of all buildings near the discharge. The perimeter fence around K-25 and the awareness of
professional personnel help deactivate many pathways of exposure; this in turn reduces present
risk. The SW31 discharge, although potentially harmful, presently does not expose people to
significant risks because of institutional controls.
The pathway of exposure for all potential human receptors is inhalation of volatilized
organics from the water stream. Table 2.4 shows the toxicity assessment for the professional
sampler, and Table 2.5 shows toxicity assessment for the general plant worker. These tables
comprise the quantitative evaluation of both carcinogenic and noncarcinogenic effects. Excess
risk quantifies the increase in probability that an individual will develop cancer when exposed to
contaminants. This represents the risk to contract cancer solely because of contamination. The
estimate involves the evaluation of many assumptions, including duration, manner, and level of
exposure. Experimental sampling results are the starting point for estimates and computations.
EPA requires estimation procedures that lead to upper-bound results, that is, estimates that are
very conservative in the interest of human health and the environment. Excess risk is expressed
as a probability and varies between 1 and 0; a value of 1 represents statistical certainty, while a
smaller number shows a proportionally lower risk.
While the risk of cancer is given as an incremental probability, the danger of
noncarcinogenic harmful effects is obtained by comparison with threshold reference doses. A
reference dose is an estimate of the daily exposure level likely to be harmless during a lifetime.
If the actual dose exceeds this threshold (the ratio of actual dose to reference dose—hazard
quotient—is larger than 1), there may be potential harm in exposure.
Excess cancer risk from exposure to contaminated water is estimated to be 4 x 104 for
the sampler and no more than 5 x 10* for the general plant worker. In other words, a
professional sampler is 40 chances in a billion more likely to contract cancer in a lifetime than
if no contamination existed at SW31; a general plant worker is no more than SO chances in a
Dnm.2JM3i 2-12 0*17/92
-------
nose *.«. n»n«n noup ran •sBacauea wiin mmnauua «• vuu iron ine ik*iv/v tmji
•Cs^QQDQW
Oacer
SlaBB fftH*
— r- — .-,-*
* li», .
Wstor
(mg/L)
isimxtmifo IWB lift J fi
Air
cuoceiitisiiuo tntake
loswijr (mg/kg/d)
(mg/m1)
il/mm
LlfBtilBB
excess
cumn risk
Discherge nte 0 6 gil/mio
Air
cooceatnlion
1 mmaqr
(mg/m1)
(mg/kg/d)
LUedme
excess
CARCINOGENiC EFFECTS
Benzene
Chloroform
Memykae chloride
Tetnchtoroefhene
1.1,2-
TncMoroeuttDe
TnchloroetbcfiB
Vinyl chloride
NONCARCINOGENIC
1« *fc* -•-• -*
, i -ncnioroeninB
EAylbeuBBB
TohMae
1,1,1-
T.t.Mn it
IKIIIOrOeiBBBB
Xytenes
2.9B42
8.1&02
1.4E-02
4.7E-07
5.2E-07
5.7E-02
1.7E-02
8.4E-05
EFFECTS
1.0B400
1.0B-fOO
2.0E-KW
3.0B-I-00
3.0E-OI ,
1.3E+00
5.0E-03
5.0E-03
8.0E400
1.1E-OI
2.3E-02
4.3E-01
I.4E-01
3.8E+00
4JE-01
3. IE +00
1.1E+01
1.9E4-00
2.4E-01
9.2E-03
7.0E-04
1.6E+00
1.8E-02
3.9E-03
7.4E-02
3.0E-02
. ...
7.2E41
6.6E-02
5.IE-OI
I.8E+00
¥U,- ••••;.«. • .
3.5E-01
4.0E-07
1.8E-08
1.4E-09
3.IE-06
3.4E-08
7.5E-09
1.4E-07
5.7E-08
3.9E-06
3.0E-07
2.8E-06
". i. ,'i' '. -
I.OE-05
ll9E-fl6
1.1E-08
1.4E-09
I.9E-11
1.SE-I2
1.8E-14
4.3E-10
2.4E-09
4.8E-12
2.0E-08
3.9E-06
3.0E-07
1.4EO6
3.3E-06
6.3E-06
4.7E-01
2.0E-03
l.OE-03
3.26E+00
3.5E-02
8.0E-03
1.5E-01
5.9E-02
I.44B+00
1.3E-01
I.02E-KW
, - , •
3.7E+00
7.0E-01
9.0E-07
3.0E-09
I.OE-09
6.4E-06
6.8E-08
1.5E-08
2.9E-07
1.2E-07
7.9E-06
7.2B-07
S.6E4X
2.0E-05
3.8E-06
2.6E-08
2.4E-10
1.4E-11
3.0E-12
3.5E-14
8.5E-10
4.9E-09
9.7E-12
4.2E-08
7.9E-06
74B-0?
2.8E-06
6.8E-06
1.3E-05
Somrtt: K-1O70 SW3I Tecfuiical IttmM amlmi, Jau 1992
-------
Table 1^. Hunan heaJta rfedn aswdated
with inhalation «f VOCs from the K-lt7t SW31
for the plant employee
1 • •.' Discharge rate Q 3 fal/min
a
^j-QPtamBPtflt
C«~
Water
slope factor concentration
(mg/kg/dy1 (mg/L)
CARCINOGeNIC EFFECTS
Benzene 2.9E-02
1
t
i
Chlorofonn
Hexachkxoethane
Methykoe chloride
Tetnchloroethylene
1,1.2-
Trichloroethane
Trichloroethylene
Vinyl chloride
Total pathway riak
NONCARCINOGENIC
l.l-Dtcaloroethane
Ethylbauene
Tohwne
I.I.I-
Trichloroethane
Xylenea
8.1E-02
1.4E-02
4.7E-07
5.2E-07
5.7E-02
1.7E-02
7.1E-09
EFFECTS
l.OE+00
l.OE+00
2.0E+00
3.0E+00
3.0E-01
1.3EH-00
5.0E-03
S.OE-03
8.0E+00
1.1E-01
2.3E-02
4.3E-01
1.4E-01
3.8E+00
4.3E-01
3.1E+00
1.1E+01
1.9E+00
Air
10m away
(rag/in1)
2.9E-02
1.1E-03
8.7EX15
2.0E-01
2.2E-03
4.8E-04
9.1E-03
3.7E-03
8.9E-02
8.2E-03
6.3E-02
2.3E-01
4.3E-02
Intake
(mgAg/d)
6.7E-04
2.6E-05
2.0E-06
4.7E-03
5.0E-05
1. IE-OS
2.IE-04
8.5E-05
5.8E-03
S.3E-04
4.1E-03
1.5E-02
2.8E-03
Lifetiine
excess
cancer risk
2.0E-05
2.1E-07
2.8E-08
2.2E-09
2.6E-J1
6.3E-07
3.6E-06
7.1E-09
2.6E-05
5.8E-03
5.3E-04
2.1E-03
4.9E-03
9.3E-03
Discharge rate 0 6 gal/min
Air
concentration
10m away
(rng/rn1)
S.8E-02
2.0E-04
2.0E-04
4.0E-01
4.0E-03
l.OE-03
1.8E-02
7.0E-O3
1.8E-01
1.6E-02
1.3E-01
4.6E-01
8.6E-02
Intake
(rng^g/d)
1.3E-03
4.6E-06
4.6E-06
9.4E-03
9.3E-OS
2.3E-05
4.2E-04
1.6E-04
1.2E-02
l.OE-03
8.3E-03
3.0E-02
5.6E-03
Lifetime
excess
cancer risk
3.9E-05
3.8E-07
6.5E-08
4.4E-09
4.8E-11
1.3E-06
7.1E-06
1.4E-08
4.8E-05
1.2E-02
l.OE-03
4.1E-03
l.OE-02
1.9E-02
Stmrct: K-1070 SW3I Ttdmical Memonatdmt. Jtau 1992
-------
million more likely. According to the EPA, an excess cancer risk greater than 10* (1 in a
million) is the lower threshold for concern,-while an excess cancer risk greater man 10~* (1 in
10,000) needs very dose attention. Therefore, excess risk for the sampler is insignificant, while
excess risk is below the upper threshold of concern for the general plant worker. Risk of
noncarcinogenic toxicity for the sampler and the worker is absent; the hazard quotient is well
below the value of 1.
The modest risk to human population under present circumstances is an insufficient
reason to dismiss the need of interim action for SW31. Ecological risk is a reason for concern.
The ecological receptors most at risk from SW31 are aquatic organisms in Mitchell Branch.
Insufficient data exist for a quantitative evaluation of this risk, but some evidence is available
regarding acute toxicity on test organisms.
Two tests were performed with samples from the SW31 discharge to verify the barm to
aquatic life from acute toxicity. In both cases, half the test organisms placed hi a mixture of
clean water and as little as 4 to 6% of SW31 discharge died within 48 hours. This gives rise to
the qualitative assertion mat risk exists. However, streams from SW31 are combined with other
sources of water and contaminants before discharge into Mitchell Branch. Available information
is insufficient to determine the present effect mat the SW31 discharge alone would have on
Mitchell Branch.
DESCRIPTION OF ALTERNATIVES
As previously discussed, the primary mechanism for release of contaminants to the
environment from the SW31 spring is direct discharge of contaminated spring water to the K-25
storm drain system. The storm drain conveys flow from the SW31 spring to Mitchell Branch.
The objective of mis interim remedial action for SW31 is simply to terminate the direct
discharge of contaminants to surface waters by intercepting and routing contaminated waters for
treatment prior to discharge to surface waters via a NPDES-permitted outfall. The contaminants
found in the SW31 spring are amenable to removal by proven physical/chemical treatment
technologies.
Three treatment alternatives were identified. Each of these, as well as a no-action
alternative, was subjected to a detailed analysis that applied the nine evaluation criteria established
by the SARA and NCP.
2-15
-------
The no-action alternative, which is required to be evaluated for all CERCLA remedial
actions, serves as a baseline for comparison against the other alternatives and must be carried
through the detailed analysis of alternatives. The no-action alternative does not include any active
response measures, but rather consists solely of monitoring and activities in support of
monitoring.
Alternative 1, No Action
CERCLA requires that the no-action alternative be evaluated at every site to establish a
baseline for comparison. Under this alternative, no further action would be taken at the site to
reduce risk to human health and the environment from water contamination. Therefore, no
cleanup would be performed, and current site risks would not be mitigated.
The no-action alternative includes monitoring of ongoing contamination. Under this
alternative, SW31 would be monitored quarterly until a final remedial action for K-1070 OU is
undertaken.
This alternative may not meet the requirements of the Fish and Wildlife Coordination Act
[16 United States Code (USC) 661 et seq.] as the discharge to a storm drain and then to Mitchell
Branch creates a potential risk to fish and wildlife. Also, the Tennessee Department of
Environment and Conservation (TDEC) Water Quality Control Act [Chapter 1200-4-3.03(g) of
the Rules of TDEC] prohibits the discharge of toxic substances that would impact the growth of
aquatic life. In addition, renewal of the K-25 NPDES permit will impact the current practice of
routing the untreated stream to a storm drain.
Radiation protection standards are not expected to be violated. These standards are
presented in DOE Orders 5400.5 and 5480.11; although not ARARs for remediation, these
documents are to-be-considered regulations and are legally binding for DOE's contractors.
This alternative does not reduce the current risk to health and the environment.
Alternative 2, Carbon Adsorption
Carbon adsorption has been used extensively to remove many organic compounds from
contaminated waters. The removal process relies on the affinity between contaminants and
activated carbon particles. Besides organics, activated carbon can also adsorb some inorganic
constituents, even in low concentrations.
DOM09.2JM31 2-16 0*17/95
-------
A commercially available carbon adsorption treatment system is die primary means for
the remediation of SW31 under mis alternative* .Column-type systems allow efficient use of
adsorption capacity. For mis alternative, an off-the-shelf, skid-mounted unit.would be used.
With minimal infrastructure (a pump station and a concrete slab), mis equipment would become
an operative treatment unit. Once the carbon is exhausted and cannot adsorb any more
contaminants, the skid-mounted unh may—if certain conditions are met—be shipped back to the
vendor tot regeneration while a stand-by replacement is put in service.
Contaminated waters from SW31 would require pretreatment to remove suspended solids
and other fouling agents mat hinder the operation of treatment by carbon adsorption.
Pretreatment is required at least for iron and manganese, which are detected in relatively large
concentrations in SW31. An off-the-shelf pretreatment system with capability for oxidation, pH
adjustment, and flocculation/clarification has been considered because it will be effective even
for the high concentrations of iron and manganese that have been found.
Water from the spring would flow through a commercial pretreatment unh and then to
the carbon adsorption treatment system. The reactor stream 'would eventually discharge to a
storm dram and on to Mitchell Branch.
Pretreatment unit and main treatment system maintenance and replacement needs must
be determined through stream monitoring. However, the analysis of SW31 waters and a
theoretical evaluation of mis treatment system show mat maintenance and regeneration of
activated carbon as the primary means of treatment would be very demanding. The type and
amount of contaminants present in SW31 would rapidly exhaust large quantities of activated
carbon,' creating an unrealistic need for maintenance. Besides, residual toxichy not amenable to
removal by activated carbon may remain in the stream, and implementing mis alternative may
present technical complications.
Due to traces of radioactivity in the water, mis alternative could also result in the
generation of relatively large volumes of mixed waste from carbon adsorption since carbon may
concentrate the radioactive contaminants. If mixed waste is generated, die carbon will not be
returned to the vendor for regeneration, but will be stored and disposed of as explained in the
waste management plan, which will be prepared as part of the remedial design work plan. The
pretreatment unh may also generate hazardous or mixed waste as a by-product of cleaning the
water.
2-17
-------
Because of the potential presence of heavy metals in the stream, there are still some
unknown factors involved with this alternative relative to its compliance with the Fish and
Wildlife Coordination Act, die TDEC Water Quality Control Act, and the forthcoming K-25
NPDES permit Compliance with radiation protection standards is expected.
Standards for the operation of miscellaneous treatment units are codified in 40 Code of
Federal Regulations (CFR) 264.601. These standards require location, design, operation, and
closure of the unit in a manner protective of human health and the environment. If the treatment
system will include tank(s), regulations on tank storage, operation, and closure hi 40 CFR
264.111 and 264.190 et seq. may be applicable or relevant and appropriate for mis remedial
alternative. This will depend on whether the new units are part of a wastewater treatment system
subject to regulation under Section 402 of the Clean Water Act. In the latter case, the tank
standards would not be applicable but may be relevant and appropriate.
The expected performance of the carbon treatment system will provide effluent quality
in compliance with the cleanup standards (MCLs) listed in Tables 2.1 and 2.2. The heavy metals
detected in SW31 probably contribute to the toxicity to aquatic life: the cleanup standards (MCL)
of Table 2.3 can be attained, but the pretreatment stage may require modifications to include
cleanup of metals.
Treatment residuals will be tested before disposal. If the residuals are
RCRA-characteristic waste, the Land Disposal Restrictions of 40 CFR 268 will apply. If mixed
waste, they will also be handled according to DOE Order 5820.2A, Radioactive Waste
Management.
This alternative neutralizes current risk to human health and may neutralize risk to the
environment. Field confirmation of the effectiveness of treatment is needed as this result is
possible but not guaranteed.
Capital costs associated with Alternative 2 are estimated at $230,000 with annual
operation and maintenance costs at $380,000. This alternative will require 10 months for
implementation.
Alternative 3, Air Stripping and CNF Treatment
Air stripping is a process through which volatile compounds are transferred from water
to air, thus cleaning up the water. In turn, stripped contaminants become gaseous and volatilize
in the atmosphere. A large volume of air is required to strip volatile contaminants from water;
gaseous contamination is therefore diluted before it is released to the atmosphere. Compliance
2-18 OW17/92
-------
with air emissions standards may require cleanup of the gaseous emissions. Air stripping is only
effective for removing contaminants that vaporize easily; for example, ft cannot extract metals.
An air stripper is a device used to create conditions favorable to the gasification of
contaminants dissolved in water. For this alternative, a standard design air stripping tower
available off-the-shelf from a commercial supplier in a standard design wfll be skid-mounted and
put in service with minimal infrastructure. If air emissions are excessive, a commercially
available gas control system or another acceptable solution in compliance with applicable air
quality regulations (Chapter 1200-3-3 of the Rules of the TDEC) will be used to mitigate mis
problem.
The stream from the air stripper is not sufficiently clean to be discharged although VOCs
have been removed. For instance, PCBs may still be in the water since they are not likely to be
removed by air stripping. Heavy metals would still be hi the water. The CNF can remove
metals but cannot treat PCBs; therefore, PCBs would have to be cleaned up before the water was
pumped to the CNF. This can be accomplished through a stream polishing stage by means of
activated carbon. After air stripping of VOCs, carbon is an effective and efficient technology
for polishing the water.
Overall, for mis alternative the contaminated water from SW31 would first go through
preliminary treatment, as considered for Alternative 2 to remove fouling agents. After
pretreatment, the water will flow to the stripping tower for removal of VOCs and then to carbon
polishing. The polished stream is eventually routed for treatment to the CNF, an
NPDES-permitted facility, for subsequent discharge at Outfall Oil. The CNF is about 0.5 mile
from die SW31 site.
The pretreatment unit would require maintenance as determined by stream monitoring,
and the air stripping tower may require periodic acid washes to prevent fouling. Air stripping
wfll generate gaseous emissions. Theoretically, off-gas control does not appear necessary, but
if it were, the potential advantage of off-gas control vs carbon adsorption as the mam water
treatment is that since air emissions are free from radionuclides, the carbon used will not be a
mixed waste.
The rate of exhaustion of activated carbon b the polishing stage is modest; thus, if
applicable, the volume to handle as mixed waste is also small. The potential for generation of
hazardous or mixed waste from the pretreatment stage is the same as in Alternative 2.
2-19
-------
In addition to the ARARs cited for previous alternatives, the air quality standards in
Chapter 1200-3-3 of the Rules of TDEC would apply to this remedial alternative. Besides, the
polishing stage stream must meet the waste acceptance criteria of the CNF (listed in The Oak
Ridge Gaseous Diffusion Plant K-J407-H and K-1407-A Central Neutralization Facility Waste
Acceptance Criteria).
The expected performance of the treatment system will provide effluent quality in
compliance with regulations. Cleanup standards as the MCLs listed in Table 2.1, 2.2, and 2.3,
or the mandates of the K-25 NPDES permit for outfall 011 are attainable.
This alternative neutralizes current risk to human health and the environment.
Capital costs of Alternative 3 are estimated at $350,000 with annual operation and
maintenance costs at $120,000. This alternative requires 10 months for implementation.
Alternative 4, Air Stripping and Direct Discharge
This alternative, like Alternative 3, includes pretreatment, air stripping, and carbon
polishing. It differs from Alternative 3 because, after being polished, the stream is directly
discharged to a storm drain instead of being transferred to CNF for further treatment.
Toxichy testing of the polished stream before release to the environment would be
necessary to verify the viability of this discharge option. Without a pilot test, mis alternative's
feasibility cannot be quantitatively evaluated or effectively determined.
Carbon polishing would remove residual PCBs. However, the heavy metals detected in
SW31 probably contribute to the toxicity to aquatic life and may flow through the treatment
system. Conversely, the pretreatment stage could possibly be modified to extend its function to
include cleanup of metals. This modification, in turn, could require the addition of treatment
chemicals that may be harmful to the environment if not removed, and the modification may only
be partially successful.
The implementability of this alternative remains uncertain without field verification.
However, it would probably be more involved than Alternative 3 and require some design
modifications.
Maintenance and replacement times for the pretreatment unit and the activated carbon
system would need to be determined through stream monitoring. The air stripping tower would
require periodic acid washes to prevent fouling. Generation of waste would be similar to
Alternative 3, with some uncertainty about the need for different chemicals for pretreatment.
DOMB.2MS1 2-20 «m/»
-------
There are no additional ARARs besides those examined for Alternatives 1, 2, and 3. As
in Alternative 2, there is uncertainty about compliance with the Fish and Wildlife Coordination
Act, die TDEC Water Quality Control Act, and the forthcoming K-25 NPDES permit because
of the potential presence of heavy metals in the stream.
This alternative neutralizes current risk to human health and may neutralize risk to the
environment. Field confirmation of the effectiveness of treatment is needed u this result is likely
but not guaranteed.
Capital costs of Alternative 4 are estimated at $260,000 with annual operation and
maintenance costs at $120,000. This alternative would require 10 months to be implemented.
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Decision Matrix
Table 2.6 shows a schematic summary of the following analysis.
Overall Protection of Human Health and the Environment
Alternative 1 does not offer sufficient protection of human health and the environment;
baseline conditions are not acceptable. Alternatives 2, 3, and 4 offer satisfactory protection from
exposure to the contaminants discharged by SW31 by removing the contaminants from the water
minimizing harmful effects through treatment.
Alternatives 2, 3, and 4 intend to achieve the same result through solutions mat are
technically different. Alternative 3 provides for the protection of health and the environment
through final stream polishing at an NPDES-permitted facility. The level of protection offered
to human health and the environment for Alternatives 2 and 4 depends on resolving the remaining
uncertainty about the impact to wildlife from residual contaminants hi the discharge.
Compliance with ARARs
Chemical-Specific ARARs: Alternative 3 is expected to meet chemical-specific
regulatory limits for discharge. Alternatives 2 and 4 can possibly meet these limits as well. CNF
treatment, which results in an NPDES-pennitted stream, meets radiation protection standards for
.2-21 own/a
-------
Table 2.f. SW31 Leaehate Stream: evaluation of alternatives for interim rancdiatkM
1
1
2
3
4
Alternative
No Action
Carbon Adsorption
Air Stripping and CNF
Treatment
Air Stripping and
Direct Discharge
Protection
o
/
/
/
ARARS
O
/
/
/
EflectiTe-
ness
N/A
0
/
•
Reduction of
mobility
N/A
•
/
/
Short-
term
N/A
/
/
/
ImnJMiiaiit
impKuiaH*
ability
N/A
•
/
•
Cort
N/A
O
•
/
Kl
^
K>
Unsatisfactory
Intermediate
Good
N/A - Not Applicable
-------
Alternative 3. In view of the very minimal radiological contamination of SW31, it is also
expected mat Alternatives 2 and 4 will comply, but field verification would be necessary to
••certain compliance with DOE Orders 5400.5 (2/8/90), 5820.2A (9/26788), 5480.11 (7/20/89),
and the as tow as reasonably achievable principle.
Location-Specific ARARs: In the immediate proximity of SW31, it appears mat the
direct environmental impact would be limited to siting the temporary treatment system.
Action-Specific ARARs: Standards for operation and maintmance of miscellaneous
treatment units in 40 CFR 264.601 are applicable to the components of die remedial alternatives
studied. Tank storage regulations in 40 CFR 264.111 and 264.190 et seq. may be applicable or
relevant and appropriate, as discussed previously. Treatment residuals and by-products must be
tested before disposal and managed as hazardous or mixed waste, as applicable. Alternatives 2,
3, and 4 can comply with these regulations. Air emissions from the air stripper must meet state
ambient air quality standards. The NPDES permit in force at K-25 establishes the regulatory
framework for the treatment of discharge and their release to the environment. Discharges to
Mitchell Branch are prohibited if they contain toxic substances that could cause specific toxic
effects or hinder growth of aquatic life. For Alternatives 2 and 4, this will need technical
attention during implementation.
Long-Tenn Effectiveness and Permanence
Long-term effectiveness and permanence of an interim solution should be evaluated with
the understanding mat mis remedial initiative is temporary. Regulatory guidance recommends
that temporary remediation be evaluated in the framework of overall she strategy. For instance,
an interim remedy should be considered effective until a permanent remedy can be implemented,
but its suitability for incorporation into the permanent solution should be examined, if possible.
No information is available today on a future permanent remedial solution for SW31. It is
therefore impossible to answer mis question with any certainty at mis time.
Alternative 2 demands constant maintenance. Removal of the type and amount of
contaminants found in the SW31 discharge requires large quantities of activated carbon and will
impose an impractical maintenance burden. Carbon adsorption will perform poorly in the short
term and is not a viable long-term solution. In addition, the presence of residual toxictty in the
stream is possible.
The effectiveness and permanence of Alternative 3 is good. This alternative requires
transportation of water to the CNF, and collection of environmental remediation discharge at the
CNF is endorsed by the NPDES permit at K-25. Successful treatment in mis facility is
2-23
-------
guaranteed once the waste acceptance criteria are met. Discharge occun at Outfall 011, which
is monitored under the authority of the NPDES permit. Incorporation in a long-term solution
may be possible, but this advantage is speculative at present.
For Alternative 4, which releases treated waters into Mitchell Branch, stream monitoring
from the polishing stage will require constant attention. Also, field verification of effectiveness
is necessary to confirm the degree of cleanup that can be obtained.
Reduction of Toxidty, Mobility, or Volume Through Treatment
Reduction of toxicity, mobility, or volume is a complex objective that is seldom fulfilled
in all its aspects. All alternatives will generate waste that may be RCRA-listed or mixed as a
by-product of the pretreatment stage. Alternative 2, if implemented, would produce very large
amounts of exhausted activated carbon that require either regeneration or handling as mixed
waste. Alternatives 3 and 4 will produce air emissions that may potentially require cleaning with
commercial off-gas control equipment even if this appears unnecessary. These alternatives also
require regeneration of the polishing stage. For all alternatives, pretreatment may generate
hazardous or mixed waste. All by-products of water treatment need to be monitored and tested
as appropriate. If by-products are classified as hazardous or mixed waste, their management and
disposal will comply with applicable regulations.
Short-Tenn Effectiveness
Alternatives 2, 3, and 4 have very similar short-term impacts as a result of incidental
construction requirements. For example, the necessity of rerouting the contaminated discharge
creates a potential risk for all personnel involved in construction. Having workers near SW31
while it is untreated is not desirable, but this risk can be managed effectively. Impact of
construction on the environment is considered negligible. Human communities outside the
perimeter fence of K-25 will not be affected by activities related to the implementation of a
remedial alternative.
The effectiveness of all action alternatives is prompt. Protection of the environment from
contamination is achieved immediately after the operation begins.
ImptementabiDty
All remedial alternatives are based on mature technologies, but implementation may
require design modifications for Alternatives 2 and 4 based on results from field tests. The goals
projected for each alternative are technically realistic in the scope of the alternative; however, the
2-24 ownm
-------
lack of a field pilot study creates some uncertainty. For timely remediation, a higher degree of
uncertainty in the design was preferred over a longer period of engineering development. The
administrative feasibility of these alternatives depends on the achievement of a consensus among
DOE and regulatory agencies involved in the evaluation and approval process.
Cut
Order-of-magnitude costs for capital expenditure vary from $230,000 (Alternative 2) to
$350,000 (Alternative 3). Annual operation and maintenance costs vary from $120,000
(Alternative 3) to $380,000 (Alternative 2). Alternative 4 costs are intermediate. There is
significant uncertainty in these estimates. The lack of a pilot test leaves a broad margin of
indetermination, for instance, on the characterization of by-product wastes and on other issues,
as previously discussed.
State Acceptance
The state of Tennessee has reviewed the alternatives proposed for interim action at SW31.
TDEC concurs with the selection of Alternative 3, Air Stripping and CNF Treatment, as the
alternative best suited for interim remediation of SW31 Leachate Stream.
Community Acceptance
During the public comment period for the Proposed Plan for the remediation of SW31,
several comments and questions were presented about the proposed alternative. There was,
however, consensus about the appropriateness of Alternative 3 for interim action at SW31, and
the public agreed with the selection of this alternative. The Responsiveness Summary of this
ROD addresses the questions and comments from the public in detail.
THE SELECTED REMEDY
Based on consideration of the requirements of CERCLA, the analysis of the alternatives,
and public comment, DOE, EPA, and the state of Tennessee have determined mat Alternative 3,
Air Stripping and CNF Treatment, is the most appropriate remedy for interim action at the SW31
Perennial Spring, K-25 She 1070 OU, Roane County, Tennessee.
Alternative 3 comprises the installation of a pretreatment unit, an air stripping tower, and
a carbon adsorption polishing stage available off-the-shelf from commercial vendors. Discharge
from SW31 would be treated through this system and then routed to the CNF—an
NPDES-pennitted facility—for final treatment to remove all residual contaminants in the water.
DCTKP.MMM 2-25 OW17/W
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Up to 9000 gal/d of water would be treated. Figure 2.3 shows a simple flow diagram to illustrate
the various treatment stages.
The purpose of this response action is to control potential risk to health and risk to the
environment posed by the contamination of the SW31 stream. Existing conditions at the site pose
an excess lifetime cancer risk of 5x 10~5 to the general plant worker. This risk relates to the
organic contamination of SW31 discharge, which discharges approximately 2.4 Ib/d of VOCs to
the environment. This discharge is currently being routed to a storm drain. In addition, there
is evidence that SW31 stream discharge is toxic to aquatic life, probably because of its heavy
metals concentrations.
This interim action will treat the discharge, which will be able to eventually be discharged
as an NPDES-permitted stream. This action will result in neutralization of the risk to health and
the environment that SW31 currently poses. Within 10 months from this ROD, "substantial
continuous on-site physical remedial action" [SARA 120(e)(2)] will have been implemented.
The expected performance of the treatment system will provide effluent quality in
compliance with regulations. Cleanup standards, such as the MCLs listed in Tables 2.1,2.2, and
2.3 and the mandates of the K-25 NPDES permit for Outfall Oil, are attainable.
Table 2.7 presents an estimation of the capital costs of each major component of the
selected remedy. Table 2.8 states operation and maintenance costs in terms of annual costs. A
present value is not computed because of the interim nature of this action.
The operation and maintenance costs may continue consistent with the length of duration
of the environmental restoration of the K-25 Site.
STATUTORY DETERMINATIONS
Protection of Human Health and the Environment
The selected remedy protects human health and the environment from the contaminated
stream of SW31 Perennial Spring through treatment and discharge of an NPDES-permitted
stream. All pathways of exposure for possible human receptors and for wildlife and the
environment are deactivated through source control measures by treating SW31 discharge. There
are no short-term risks associated with the selected remedy that cannot be effectively managed,
and no adverse cross media impacts are expected from the remedy.
DWM0821MM 2-26 OW17/92
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Spring
Leachat*
PratrMtnent
Ft itrate
Filter
Pre»*
Air
Stripper
Off-«
Carbon i
Adsorption L
ryj |
Off-gas
Diacharg*
Carbon
Adsorption
CNF
NPOES
Effluent
Spent
Carbon to
He generation
or Disposal
Fig. 2J. Selected tmtmcnt system for SW31.
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Table 2.7. Capital costs
Component
Co*
Pntnatment lyctem
Filter press
Onuiular activated carbon unit
Air atripping tower
Pumps and pipe*
Temporary building
Wiring and installation
Polypropylene pipe to CNF
Pipeline infrastructure
Engineering costs
15% contingency at start-up
$ 60.000.00
10,500.00
4,500.00
17,000.00
18,800.00
35,000.00
41,000.00
32,500.00
6,250.00
83,000.00
46,000.00
TOTAL
$ 354,550.00
Table 2.8. Operation and maintenance costs
Yearly cost
Sludge .disposal
Carbon
Chemicals
Utilities mru^ miacells
us costs
TOTAL
$ 55,000.00
2,700.00
50,000.00
10.000.00
$ 117,700.00
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OW17/R
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Compliance with ARARs
Hie selected remedy of discharge treatment through pretreatment, air stripping, carbon
polishing, «nd final CNF treatment will comply with all chemical-, action-, and location-specific
ARARs for the limited scope of mis interim action. ARARs are presented below.
Chemical-Specific ARARs: State Water Quality Criteria (Rules of the TDEC
Chapter 1200-4-3), Safe Water Drinking Act MCLs, and the NPDES permit in force at K-25.
Although not ARARs, the waste acceptance criteria of CNF must also be met. Radiation
protection must comply with standards as set forth in DOE Orders 5400.5 and 5480.11 and
radioactive waste management criteria of DOE Order 5820.2A. Land Disposal Restrictions in
40 CFR 268 will be adhered to.
Location-Specific ARARs: The selected remedy must also comply with the Fish and
Wildlife Coordination Act (16 USC 661 et seq.) and the TDEC Water Quality Control Act
[Chapter 12(XM-3-.03(3g) of the Rules of TDEC].
Adion-Spedftc ARARs: The following action-specific ARARs must be met: Treatment
in a Unit, 40 CFR 264.601; Tank Storage. 40 CFR 264.111,264.190 et seq.; Leaks or Spills,
40 CFR 302.4,302.6; Disposal of Treatment Residuals, 40 CFR 268, DOE Order 5820.2A; Air
stripping, ah- quality standards (Chapter 1200-3-3 of the rules of TDEC), 40 CFR 265.1032(a)(l).
In addition, the Proposed RCRA Subpart CC, 56 Federal Register (FR) 33490. July 22, 1991,
is to-be-considered.
Cost Effectiveness
The selected remedy is cost-effective. The overall relationship between the benefit
offered and the expenditure necessary to obtain it compares favorably to mat of the oner
alternatives studied.
Use of Permanent Solutions and Treatment
Because mis is an interim action, the use of permanent solutions needs to be considered
only in the framework of long-term integration with final remediation for mis OU. Presently,
no information is available to this regard. Any conclusion would be speculative and, therefore,
irrelevant as a statutory determination
DMMBJIMU 2-29 OWIT/W
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While the alternatives studied are comparable in implementability and short-term
effectiveness, the selected alternative presents a more favorable trade-off between cost and
effectiveness of remediation. The discharge of an NPDES stream is a guarantee of performance
and reliably pursues the reduction of toxicity to aquatic life.
Reduction of toxicity, mobility, or volume through treatment was the most decisive factor
in the selection of mis remedial alternative. The state and local community concurred with the
rationale behind mis choice.
Although not a permanent solution, the selected remedy meets the statutory requirement
to use treatment technology to the maximum extent practicable.
Preference for Treatment
This interim action satisfies the statutory preference for treatment as a principal element.
However, h does not definitively address the principal threats to health and the environment
posed by OU K-1070. Future action for this OU will be addressed under the remedial
investigation scheduled to start in late 1992.
DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for interim remediation of SW31 Perennial Spring, K-25 Site, was
released for public comment during July 1992. The Proposed Plan identified Alternative 3, Air
Stripping and CNF Treatment, as the preferred alternative. DOE reviewed all comments
submitted during the public comment period. Upon review of these comments, it was determined
that no significant changes to the remedy as it was originally identified in the Proposed Plan were
necessary.
BIBLIOGRAPHY
Martin Marietta Energy Systems, Inc., The Oak Ridge Gaseous Diffusion Plant K-1407-H and
K-1407-A Central Neutralization Facility Waste Acceptance Criteria, K/SS-538, U.S.
Dept of Energy, February 1990.
Martin Marietta Energy Systems, Inc., Phase 2 Remedial Investigation Work Han for the K-1070
CJD Classified Burial Ground at the Oak Ridge K-25 Site, Oak Ridge, Tennessee, Vol.
1: History. Environmental Characterization, and Project Scope, ES/ER-9/V1&D1,
K/ER-32/V1, U.S. Dept. of Energy, June 1991.
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Martin Marietta Energy Systems, Inc., RCRA Facility Investigation Plan, K-1070 C/D Classified
Burial Ground, Oak Ridge Gaseous Diffusion Plant, Oak Ridge, Tennessee, K/HS-140
Revision 1, U.S. Dept. of Energy, May 1989.
Martin Marietta Energy Systems, Inc., RCRA Facility Investigation Plan General Document, Oak
Ridge Gaseous Diffusion Plant, Oak Ridge, Tennessee, K/HS-132, U.S. Dept. of Energy,
March 1987.
Martin Marietta Energy Systems, Inc., Resource Management Plan for the Oak Ridge
Reservation, Vol. 4, Appendix D, ORNL-6026/V4, U.S. Dept. of Energy, July 1984.
Martin Marietta Energy Systems, Inc., Resource Management Plan for the Oak Ridge
Reservation, Vol. 24. ORNL/ESH-1/V24, U.S. Dept. of Energy, January 1987.
Martin Marietta Energy Systems, Inc., Toxicity Control Plan for Mitchell Branch, K/HS-354,
U.S. Dept. of Energy, May 1991.
Radian Corporation, K-1070 SW31 Technical Memorandum, 92-225-161-49, June 1992.
Wicker, L. F., Martin Marietta Energy Systems, Inc., personal communication to B. A.
Shoemaker, 48-hr acute toxlclty tests of effluent from K-1414 garage spring conducted
during May 14-16,1991 and May 21-23,1991, June 13, 1991.
2-31
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PART 3. RESPONSIVENESS SUMMARY
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RESPONSIVENESS SUMMARY
Overview .:-.. : • •••• - -• — •••-•• *•"; •• - .^ u«» ;•'•
At the time of die public comment period, die preferred alternative for interim action at
SW31 Perennial Spring, K-25 Site, near the city of Oak Ridge in East Tennessee, addressed the
remediation of SW31 through a 3-stage treatment process. The preferred alternative in the
Proposed Plan cleaned up the discharge by means of ah* stripping, activated carbon polishing, and
final treatment at CNF, which is an NPDES-pennitted water treatment faculty at K-25. This
scheme results in the discharge of an NPDES-pennitted stream to surface waters under the
established permit for the K-25 Site.
Judging from the comments received during the comment period, support for the
proposed solution is consistent. Accordingly, the preferred alternative has been selected for
action at die SW31 she as presented in die Proposed Plan. The community expressed a
preference about routing water to CNF that has been incorporated in die selected alternative
presented in die IROD. • :
Background on Community Involvement .
SW31 Perennial Spring surfaces within the perimeter fence of K-25. Access to die site
is restricted by existing institutional controls. The contamination of S^31 has raised little
interest in the community at large because of die isolated location and restricted access to mis
spring.
The public at large has been involved in die general environmental restoration of me
bOE's&cUities on die ORR tiirough various activities on many occasions. However, interest
has focused on SW31 only hi correspondence to the public comment period of die Proposed Plan
for Interim Action at this site.
Summary of Comments Received and Agency Responses
The public comment period was held for 30 days from July 2 to July 31, 1992. Few
comments were received; diey are addressed as follows. -; -,,-.-,*••.
Comment; Routing water to die CNF via pipeline would be desirable If die time frame
for remediation would render mis solution economically viable; omerwise, trucking is preferred.
Response: The selected remedy comprises a pipeline for routing water to CNF. Its
construction will not adversely impact me time frame for remediation. On die otiier hand, diis
solution would become economical in a time frame of 6 months to 1.5 years, compared to
3-3 WOMB
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transporting water by tanker. It is not expected that a permanent solution for SW31 will be
approved before this time. The Remedial Investigation for K-1070 OU is scheduled to begin in
the later part of 1992, and the decision document for this OU is scheduled after 1996. This
schedule is subject to revision, and there is presently no assurance about a due date. It is,
however, reasonably certain that this date will make the time necessary to construct a pipeline
economically attractive when compared to trucking.
Comment; A categorical exclusion under the National Environmental Policy Act
(NEPA) that is appropriate for removal actions may not be appropriate for an interim remedial
action. This comment was addressed in the discussion of NEPA compliance in the Proposed
Plan.
Response: The categorical exclusion for removal actions in Appendix B to Subpart D
of the DOE NEPA Implementing Procedures (Federal Register, Volume 57, Number 80,
April 24,1992) at page 15156 includes actions that are "taken as final response actions and those
taken before remedial action," including "treatment, recovery, storage, or disposal of waste at
existing facilities currently handling the type of waste involved in the removal action." The
installation of an organic air stripper can be defined as a removal action because it constitutes a
form of treatment and disposal of contaminated waste taken as an interim action that will be
superseded by a final remedial initiative.
Comment: "In light of the NEPA review and subsequent Memorandum-To-File referred
to in the plan, perhaps the reference to a categorical exclusion is unnecessary."
Response: The commenter is correct. There is no requirement to cite a categorical
exclusion in light of the approved Memorandum-To-File (MTF). However, die MTF was
reviewed to ensure that its contents remained consistent with the requirements of the DOE NEPA
Implementing Procedures published April 24,1992, and to ensure that mere had been no change
in the scope of the project since the MTF was signed. It was found that die MTF was still valid.
The reference to the categorical exclusion was, however, not removed from the text as no conflict
is perceived to exist.
Comment: Why will an easily implemented solution like die selected remedy, for a
problem known since at least 2 years ago as apparent from the NEPA documentation, take 3
years to put in practice—allowing the 10 months necessary for implementation?
Response: A public comment concerning the duration of implementing the interim action
at the she and not applying the removal action hi accordance with 40 CFR 300.415 (bXl) is
acknowledged; however, during early investigations of the SW31 spring, adequate data needed
3-4 OWPSK
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to be obtained for use in planning and documenting the removal action at depicted in 40 CFR
300.415(bX4XH)(B). Additionally, due to the variable contaminants detected in die stream, mere
was initial uncertainty as to the appropriateness of an air stripper as the viable treatment
alternative. The Environmental Management Division at the K-25 Site, in consultation with the
Oak Ridge National Laboratory, initiated a research and development (R&D) study incorporating
a multi-stage bioreactor for R&D demonstration as a cost-effective, innovative technology. This
approach was initiated in keeping with EPA's encouragement to use innovative technology(ies)
where applicable on federal installations. The removal action was not initiated because the stream
did not pose an imminent threat to human health. A time-critical response was not initiated
because the stream did not pose an imminent threat to human health, although it represented a
pressing concern for possible degradation of the environment. The interim action process was
chosen as the most effective implementation of a non-time-critical response.
Remaining Concerns
At the end of the public comment period, no other concerns bad been raised by the
community.
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