United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R09-93/104
September 1993
SEPA Superfund
Record of Decision:
McClellan Air Force Base, CA
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50272-101
REPORT DOCUMENTATION '1. AEPORTHO. 2. 3. Reclplenr. Acc88.lon No.
PAGE EPA/ROD/R09-93/104
4. TItle and Subtitle 5. R8po11 Data
SUPERFUND RECORD OF DECISION 09/03/93
McClellan Air Force Base, CA 6.
First Remedial Action
7. Aulhor(.) 8. Parformlng Organization RapL NO.
9. Performing Organization Name and Add,.. 10 ProJact TuklWork Unit No.
11. ContrllCt(C) or Grent(O) No.
(C)
tG)
12. Spon8Oftng OrganIzation Name and Adctr.8 13. Type 0' Raport & Parlod Covar8d
U.S. Environmental Protection Agency
401 M Street, S.W. 800/800
Washington, D.C. 20460 14.
15. Supplamantary Not.
PB94-964526
16. Ab8trect (Umlt: 200 word8)
The 18-acre McClellan Air Force Base site is an open storage lot operated by the
Defense Reutilization and Marketing Office (DRMO) in Sacramento Valley, California.
Land use in the area is predominantly industrial, with nearby off-base residential and
light industrial areas. An aquifer, which underlies the site, provides water for
domestic and industrial uses in the vicinity of the Base. From 1957 to 1987, the Air
Force DRMO used the site for the storage, loading, and unloading-of transformers and
storage of other nonhazardous materials. In the early 1960s, waste oil was appl.ied to
site soil to suppress dust. The waste oil was collected from various facilities onsite
and consisted of hydraulic oil, degreasing solvents, transformer oils, and automotive
oils and fluids. In 1977, a portion of the site yard was paved with asphalt. In 1985,
an investigation was conducted to determine the presence of buried waste. In 1987, 1.5
to 7 gallons of PCB-contaminated oil leaked from a transformer onto the ground in the
northern portion of the DRMO storage lot. As a result, the DRMO excavated and removed
the contaminated soil to a depth of approximately 10 inches and covered the area with
clean gravel. Several onsite investigations were conducted following the oil spill,
including a 1987 investigation to verify cleanup of the spill, a 1990 shallow soil gas
(See Attached Page)
17. Document Analye18 a. Desc:rtptora
Record of Decision - McClellan Air Force Base, CA
First Remedial Action
Contaminated Media: soil, sediment
Key Contaminants: VOCs (benzene, PCE, TCE) , other organics (dioxin, PCBs), metals
(arsenic, chromium, lead)
b. ld8ntlfla"'Opa~End8d T.....
c. COSATI Field/Group
18. Availability Statamanl 19. Security CI888 (thIs Report) 21. No. 0' Paga
None 108
20. Security Cia.. (Thl. Page) 22. Prlca
None
(SM ANSI-Z39.18)
SHlnsrruct/ons on R."erse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Departm.nt 0' Comm.rce
-------
EPA/ROD/R09-93/104
McClellan Air Force Base, CA
First Remedial Action
Abstract (Continued)
investigation, and the 1992 remedial investigation. These investigations showed shallow,
but widespread contamination of soil, sediment, and surface water runoff in the site area.
The source of the contamination has been determined to be the result of discharge through
spills or leaks of transformer oils, the application of waste oils to soil, and surface
water runoff. In 1992, in response to the report of contamination of soil in the remedial
investigation, a time-critical removal action was performed, which included constructing a
fence around the area to restrict access, placing metal planking over the area to reduce
fugitive dust emissions, and placing a plastic liner over the area to prevent dust
emissions and runoff to a nearby drainage ditch. This ROD addresses an interim remedy for
the contaminated soil and sediment at the DRMO yard, as OUI. A future ROD will address a
final remedy for the soil and sediment, as OU2. The primary contaminants of concern
affecting the soil and sediment are VOCs, including benzene, PCE, and TCE; other organics,
including dioxin and PCBs; and metals, including arsenic, chromium, and lead.
The selected remedial action for this site includes capping the site using a two-inch
thick asphaltic concrete cover; excavating contaminated sediment in the drainage ditches
leading off of the site, and placing the excavated sediment under the cap; installing a
sediment trap in the excavated drainage ditch leaving the DRMO yard to collect
contaminated sediment transported offsite by storm runoff; evaluating soil conducting
treatability studies to evaluate soil treatment technologies and to select a final remedy
for the site; monitoring soil, ground water, surface water, and soil gas; and implementing
institutional controls, including deed restrictions. The estimated present worth cost for
this remedial action is $2,600,000.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific interim soil and sediment cleanup goals are based on a lifetime excess
cancer risk of l~ss than 10-6, a Hazard Index of less than 1, and meeting ARARs a~d/or
TBCs. Cleanup standards have been set at PCBs 10 mg/kg for soil from 0 to 3 feet below
ground surface (TBC); PCBs 100 mg/kg for soil and sediment greater than 3 feet below
ground surface (TBC); and dioxin 1 ug/kg for all soil and sediment (TBC). Cleanup
standards for PCBs in drainage sediment and metals have not been established.
-------
.. ...
,.
-"
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SRII) IEcalDS CTR
3Q92-CJQZ99
.. _. -_... --- __'R'_.__- ---
" .- ~~...... r.
..
'"
INS~ALLATION RESTORAT!O~ PR9GRAM- (lRPf
;"
-.
~-
,Operable Unit.B1
Interim Record 01 Decision
(ROD)
for McCLELLAN AFB, CALIFqRNIA
FINAL
JULY 1993
McCLELLAN AFB I EM
, McCLELLAN AFB, CALIFORNIA 95652-5990
'"
-"
....
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INSTALLATION RESTORATION PROGRAM (IRP)
OPERABLE UNIT Bl
INTERIM RECORD OF DECIS!ON
FINAL
,
FOR
McCLELLAN AFBIEM
McCLELLAN AFB, CALIFORNIA 95652-5990
July 1993
:-..
USAF CONTRACf NO. F04699-93-C0027
CONTRACTOR CONTRACI' NO. 602-002
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REPORT DOCUMENTATION PAGE Form Appntwd
OMS No. 0704-0188
---'----"-"-.-,----.....-- --.- --..-.--......--.....-----.-
--..-..- --~--_._-_..-_..--...-----.....-_.-...._---
-~-- ---.........- w-.......... "" --- -...-..----..... ...--......-......... oc:-
1. AGENCY USE ONLY ca...n.""'1 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED
93/07/28 FiDaI
.. Tm.E AND 8U8TITI.E 6. FUNDING NUMBERS
Interim Operable Unit Bl tlecorc1 of Deciaioo (1l0D) F046~3-C0027
e. AUTHORCSI
Radian Corpowioa
-
7. PERFORMING ORGANIZATION NAME'SI AND ADDRESStESl 8. PERFORMING ORG.t.NIZATIOPJ
REPORT NUMBER
Radian Corpowioa
10389 Old PI8cerville Road
Sacrameato, CA 95827
9. SPONSORINGIMONtTORING AGENCY NAMEISI AND ADDRESStESl 10. SPONSORINGIMONrrORlNG
, AGENCY REPORT NUMBER
McCleUam AFB
McClellan AFB, CA 95652-5990
11. SUPPlEMENTARY NOTEI
12.8. DlSTRIBUTION/AVAILAM rTY STATEMENT 12b. DISTRIBUTION CODE .
.....,
UaclassifiedlUnlimited
.13. ABSTRACT &Maximum 200 wonkJ
This ROD presents the selected muediallCtiOD for Operable Unit (OU) BI at McCleUan AFB, Saaameoto, CA. .Operable
Uait BI includes the Defease Reutilizatioa and Marlcetiag Office (DRMO) storage lot and Civil Eagiaeeriag storage lot at
McClellan AFB. The main chemicals of CODcerD are PCBs, dioxins, aDd funas which may have leaked from transformers
stored at OU B I or were coastituaats of waste oil applied to soils to CODtt'ol dust.
Part I outlines the purpose of the ROD and the selected remedy. Part D Sectioas 1.0 and 2.0 describe the site ad SectiOD 3.0
provides highlights of commuaity participatioa. Part D Sectioas 4.0 and 5.0 present results from the RI, the potaItia1 for
CODtAminant miaratiODltraasport from OU BI, ad the CWTeI1t aDd future risks associated with OU Bl. Sectioa 6.0 ideatifies
the ",~i",J lCtioa objectives and poteDtia1 remedial alterDatives. The fiaa1 seven remedial alternatives are aaa1yad aDd
compared to each other usine the criteria established in the NatiODa1 Cootiagcacy Plaa in Sectioa 7.0. The selected remedy is
presented in Sectioo 8.0.
-
.
.'"'.,
1.. SUBJECT TERMS 16. NUMBER OF PAGES
164
ROD 11. PRICE CODE
17. SECURITY aJ8£IFICATION '1. SECURITY CLASSIFICATION 19. SECURITY a AS£IFICA TION 20. UMrrATION OF ABSTRACT
OF REPORT OF THIS PAGE OF ABSTRACT
. Uaclassified Uaclassified Uaclassified Ualimited
NSN 7540-01.28().S500
Stend.reI Form 298 ',ev. 2.89.
Pr~ !Iv ANSI S1d 23a.18
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This report has been prepared by the staff of Radian Corporation under our
supervision. The presentation of information contained herein has been approved after thorough
technical review. The conclusions and recommendations in this report are based upon the data
collected in the field by Radian Corporation. We believe the data presented are of high quality.
The interpretation of these data and the conclusions drawn were governed by our experience and
professional judgement.
~ Ftkt~
Thomas F. Cudzilo, Ph.D
Registered Geologist 4473
,
'.
Randy Marx, P .E.
ineer, Civil C3~936
. .
.'- ." ~ ..
-...
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TABLE OF CONTENTS
Section
Page
PART I.
DECLARATION
1.0 SITE NAME AND LOCATION. . . . . . . . . . . . . . . . . . . . . . . . , . < l.t
2.0 STATEMENT OF BASIS AND PURPOSE. . . . . . . . . . . . . . . . . . . . 1-1
3.0 ASSESSMENT OF THE SITE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
4.0" DESCRIPTION OF THE REMEDY
. . . . . . . . . . . . . . . . . . . . . . . . 1-1
5.0 STATUTORY DETERMINATIONS. . . . . . . . . . . . . . . . . . . . . . . . 1-2
S.1 ProtectiVeI\ess .................................. 1-2
5.2 Applicable or Relevant and Appropriate
,
Recluire.ments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
- 5.3 Reduction of Toxicity, Mobility or Volume
Through Trea.tment ............................... 1-2
5.4 Use of Permanent Solutions, Alternative Treatment
or Resource Recovery Technologies. . . . . . . . . . . . . . . . . . . . . 1-3
5.5 Cost Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .°1-3
PART n.
DECISION SUMMARY
1.0 SITE NAME, LOCATION, AND DESCRIPTION. . . . . . . . . . . . .. ll-l
1.1 Site Name and Location. . . . . . . . . . . . . . . . . . . . . . . . . .. ll-1
1.2 Site Derscription ................................ ll-l
1.3 TOJX)graphy.........................:......... n-l
1.4 l.a:r1d Use . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . .. n-l
1.5 Location and Facility Layout. . . . . . . . . . . . . . . . . . . . . .'.. ll-1
1.6 Qe()logy........ ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . ll-l
:-...
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES ........... n.5
2.1 Background on Contamination Problems at McClellan AFB OU Bl. n-5
2.2 Previous Studies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ll-S
2.3 Regulatory and Enforcement History. . . . . . . . . . . . . . . . . .. n-7
F1NALRODI072I93/bU
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TABLE OF CONTENTS (CoOflDUed)
Section
Page.
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION. . . . . . . . . . .. D-3 .
4.0 SUMMARY OF SITE CHARACTERISTICS. . . . . . . . . . . . . . . . .. n~9
4.1. ~logy." ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-9 .
4.2 Conb.miQallt SoUl1:e.Are:as . . . . . . . . . . . . . . . . . . . . . . . . .. n....9
,
4.2.1 PCBs and DioxinsIFurans ... . .. . . . . . .. .. ... .. .D-ll
4.2.2 Petroleum Hydrocarbons. . . . . . . . . . . . . . . . . . . . . . D-13
. 4.2.3 SemivoJatile Organic Compounds. . . . . . . . . . . . . . . . D-IS
4.2.4 Metals................................. n-lS
4.2.5 Volatile Organic Compounds. . . . . . . . . . . . . . . . . . . D-lS
4.3 Transport of Site Chemicals. . . . . . . . . . . . . . . . . . . . . . . . . D-16
4.3.1 Contaminant Properties . . . . . . . . . . . . . . .'. . . . . . . . U-16
4.3.2 Transport Mechanisms. . . . . . . . . . . . . . . . . . . . . . . D-17
4.3.3 Persistence.............................. n-22
4.3.4 Transport Pathways. . . . . . . . . . . . ... . . . . . . . . . . . D-22
4.3.5 Potential Exposure Points. . . . . . . . . . . . . . . . . . . . . D-26
5.0 SUMMARY OF SITE RISKs ........................... D-27
5.1 Human Health. Risks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-27
5.1.1 Exposure Assessment. . . . . . . . . . . . . . . . . . . . . . . . ll-27
5.1.2 Potential Exposure Pathways. . . . . . . . . . . . . . . . . . . D-27
5.1.3 Exposure Assessment. . . . . . . . . . . . . . . . . . . . . . . . D-23
5.1.4 Risk Characterization. . . . . . . . . . . . . . . . . . . . . . . . ll-33
5.2 Ecological Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . U-35
6.0 DESCRIPTION OF ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . ll-37
6.1 Interim Oeanup Goals for OU Bl ..................... D-41
6.1.1 Soil and Stream Sediment. . . . . . . . . . . . . . . . . . . . . D-41
6.1.2 Surface Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . n-4.S
-....
6.2 Stream Sediment Remedies. . . . . . . . . . . . . . . . . . . . . . . . . D-45
F1NAlAODlO72J93/tata
ii
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TABLE OF CONTENTS (CoDtiDued)
Section
Page
6.3 Surface Water Remedies. . . . . . . . . . . . . . . . . . . . . . . . . . . U-4S
6.4 Soil Remedies. . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . U-4.S
6.4.1 Alternative 1 ~ No Action . 0 . . . . . . . . . . . . . . . . . . U-49
. 6.4.2 Alternative 2 - Capping . ~ . . . . . . . . . . . . . . . . . . . . U-49 .
6.4.3 Alternative 3 -- Excavation and Off-Site Disposal ...... ll-SO
6.4.4 Alternative 4 - Excavation, Off-Site Incineration,
and Disposal ............................. n-S2
6.4.S Alternative S - Excavation, On-Site Treatment,
DisJx>sal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-S3
6.4.6 Alternative 6 - Capping and Treatability Studies
with Potential On-Site Treatment. . . . . . . . . . . . . . . . . ll-S4
6.4.7 Alternative 7 - Excavation of Hot Spots, Off-Site
Disposal and Capping ....................... ll-S6
1
7.0 -SUMMARY OF THE COMPARATIVE ANALYSIS
OF ALTER.N'A TIVES .........................0....... D-S8
7.1 Protection of Human Health and the Environment. . . . . . . . . . . ll-S8
7.2 Compliance with ARARs .......................... ll-S8
7.3 Long-Term Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . ll-S8 .
7.4 Reduction of Toxicity, Mobility or Volume. . . . . . . . . . . . . . . ll-60
7.S Short-Term Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . ll-60
7.6 ImplementaJ>ility............................... .ll-60
7.7 Costs....................................... n-60
7.8 State Agency Acceptance. . . . . . . . . . . . . . . . . . . . . . . . '. . ll-61
7.9 Community Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . n-61
7.10 Comparative Evaluation Conclusions. . . . . . . . . . . . . . . . . . . ll-61
8.0 TIffi. SaEcrED R.EMEDY . . . . . .' . . . . . . . '. . . . . . . . . . . ... . . n--64.
."...
8.1 Description of the Remedy. . . . . . . . . . . . . . . . . . . . . . . . . ll--64.
8.2 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . n-6S
8.2.1 ProtectiVetl~ ............................ ll-6S
8.2.2 Applicable or Relevant and Appropriate Requirements. . . . ll-6S
8.2.3 Cost Effectiveness. . . . ~ . . . . . . . . . . . . . . . . . . . . . ll-67
F1NAUtODI072I93Jb&a
iii
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TABLE OF CONTENTS (Continued)
Section
"'
Page
8.2.4 Use of Permanent SolutioDS. Alternative Treatment, or
Resource Recovery Technologies to the Maximum Extent
Practicable. c . . . . . . . . < . . . c. Co ~ . . . . . . . . . . . . . n-67
. 8.2.5 Preference for Treatmmt as a Princip;l Element. . . . . . . n-67
9.0 REFERENCES
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ". . . . . . . D-68
ATTACHMENT A - RESPONSIVENESS SUMMARY for PUBUC COMMENTS
RECEIVED from JUNE 16, 1993 through JULY 16, 1993 .
ATTACHMENT B - TRANSCRIPr OF PUBUC Ml::.cTwlG ON OU Bl INTERIM
PROPOSED PLAN
ATTACHMENT C - McCLELLAN AFB OU B ADMINISTRATIVE RECORD (AR)
. INDEX (1979-1993)
ATTACHMENT D - RESPONSE TO AGENCY COMMENTS
,
"....
FlNAUlODI072I93/bU
iv
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Fagure
1~1
1-2
2-1
4-1
4-2
4-3
4-4
4-5
5-1
, 6-1
6-2
6-3
8-1
:-...
LIST OF FIGURES
Page
l.ocarion of Operable Unit Bl at McClel1an Air Force Base . . . . .-. . . . . . .. n-3
~ons Within au Bl ................ ~ . . . -. . . . . . . . . . . . . . D-4.
ilistolY' of OU Bl ................................ 0 . . c c c D-6 .
Cross-Section A-A' of au Bl .......................... . . . . . n-lO
Sediment SampliDg Locations at au Bl ......................... ll-12
Surface Water Sampling Locations in au B1 and Drainage Ditches. . . . . . . . ll-14
Schematic Diagram of Potential Transport Mechanisms at au B1 ......... n-20
Physical Features of au Bl ................................ n-24
Cancer Risk Assessment Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . ll-34
Comparative Analysis of Remedial Altemanves ..................... n-39
Inorganic Cleanup Standard Determination for au B1 Surface
Soils and Sediments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . n~
Conceptual Design of the Capping Alternative. . . . . . . . . . . . . . . . . . . . . n-51
Decision Logic Diagram for Remediation of all Media in au Bl ......... n-66
FlNAUlODI0728931ta18
v
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Table
4-1
4-2
.4-3
5-1
5-2
5-3
5-4
5-S
5-6
,
- LIST OF TABLES
Page
Chemicals of Concern at McClellan AFB au Bl .................. ~ n-9
Maximum Concentrations and Physical and Chemical PloperUes
(at 2SC) of Contaminants of Con=u in au 21 " . . , . . . . . . . . . . . . . . . n-18
Mechanisms of cae Tnmsport in au Bl . ~ . , . . c . . . < . . . . . . . . . . . . . n-21
Values Used for Intake Parameters for Current
and Hypothetical Residential Scenarios. . . . . . . . . . . . . . . . . . '.' . . . . . . n-29
Values' Used for Intake Parameters for .
Non-Residential Scenarios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . n-30 .
Can.cer Potency Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-31
Reference Doses ...................................... .n-32
Haza.rd Indices. ....................................... .ll-35
Blood-Lead Levels Resulting From Exposures
to au Bl SoU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .n-35
6-1 Specific Remedial Action Objectives for OU Bl ................ ". . . . ll-38
6-2 Interim Cleanup Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ll-42
6-3A Receiving Watl:r Limitations From the Inland Surface Waters Plan:
Protection of Aquatic Life ................................. n-46
6-3B Receiving Watl:r Limitations From the Inland Surface Waters Plan:
Protection of Human Health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ll-47
6-4 Area and Volume Calculations for PCB-Contaminated
7-1
7-2
.0"00
Soil at OU Bl . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . . . . . . .n-4.8
Comparative Analysis of Remedial Alternatives. . ~ . . . . . . . . . . . . . . . . . ll-59
Cost Sensitivity Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ll-62
FINALROD/072.8931b&8
vi
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"...
AFB
AR
ARARs
A TSDR
BGS
C
Cal/EPA
CCR
CE
CERCLA
CFR
COC
CRP
~ DeE
DOT
DRMO
DTSC
EPA
FS
glL
H
HDPE
HI
HQ
HVOC
IRP
..ISWP
I-TEF
lAG
mls .
mglkg
NCP
NPDES
ACRONYM LIST
= Air Force Base
= Administrative Record
= Applicable or Relevant and Appropriate Requirements
:; ~genc;y fOf Toxic Substances and Disease Registry
= Below ground surface
= Degrees Celsius
= California Environmental Protection Agency
~ California Code of Regulation
, = Civil Engineering
= Comprehensive Environmental Response, Compensation, and Liability Act
= Code of Federal Regulations
= Contaminant of concern
= Community Relations Plan
= Dichloroethene
= Department of Transportation
= Defense Reutilization and Marketing Office
- Department of Toxic Substances Control
= Environmental Protection Agency
= Feasibility Study
= Gram per liter
= Henry's Law constant
= High density polyethylene
= Hazard index
= Hazard quotient
= Halogenated Volatile Organic Compound
= Installation Restoration Program
= Inlands Surface Work Plan
= International Toxic Equivalency Factor
= Interagency Agreement
= Meters per second
= Milligram per kilogram
= National Oil and Hazardous Substances Pollution Contingency Plan
= National Pollution Discharge Elimination System
FlNALIlODlO72l931ta&a
vii
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OU = Operable Unit
PcB = Polychlorinated biphenyl
PCE = Tetrachloroethene
PeCDD = Pf!ntW2Iorodibenzodioxin
PeCDF c::. Pentachlorodibenzofuran
pg/L = Picograms pee liter .
ppbv = Parts per billion by volume
PRL =:= Potential Release Location
PSP = Perforated steel planking
RCRA = Resource Conservation and Recovery Act
RDIRA = Remedial DesignlRemedial Action
RID = Reference dose
RI = Remedial Investigation
RME . = Reasonable maximum exposure
ROD = Record of Decision
RWQCB = Regional Water Quality Control Board
SA = Study Area
SARA = Superfund Amendments and Reauthorization Act
SMAQMD = Sacramento Metropolitan Air Quality Management District
SVOC = Semivo1atile organic compound
SWRCB = State Water Resources Control Board
TBC = To be considezed; guidance or criteria not promulgated (and therefore not
an ARAR) that is nonetheless 8to be considered8 in developing remediation
goals
= Tetracblorodibenzodioxin congeners
= TCDD equivalents
= Tricbloroethene
= Technical Review Committee
= Toxic Substances Control Act
= U.S. Environmental Protection Agency
= Volatile organic compound
= Microgram per liter
= Microgram per kilogram
~
.-...
TCDD
TCDDeq
T<:E
. TRC
TSCA
U.S. EPA
VOC
pgIL
pgIkg
ACRONYM LIST (Continued)
"- -
FDiAUODlO72l93/tata
viii
-------
PART I. DECLARATION
1.0
SITE NAME AND LOCATION
McClellan Air Force Base (AFB)
Operable Unit (OU) Bl
McClellan AFB, California
U.s. EPA IDI CA4S70024337
2.0
STATEMENT OF BASIS AND
PURPOSE
This" Interim Record of Decision
(ROD) presents the selected interim remedial
action for OU Bl at the McClellan AFB
Superfund site. The interim action was
selected to protect human health from an
~ imminent threat in the short-term and to
prevent further migration of cont':amin:ation
while a final remedial solution is being
developed.
:.~
This document was developed in
accordance with the Comprehensive
Environmental Response, Compensation, and
Liability Act (CERCLA) of 1980 as amended
by the Superfund Amendments and
Reauthorization Act (SARA) of 1986, 42
U.S.C. 19601 et seq., and, to the extent
practicable, in accordance with the NatioDal
Oil and Hazardous Substances Pollution
C9ntingency Plan (NCP), 40 CFR I 300 ~
am.. The attached administrative record iDdex
- (Attachment B) identifies the documents upon
which the selection of the remedial action is
based.
The U.S. Environmental Protection
Agency and the Swe of California, through
the Division of Toxic Substances Control
(DTSC) and California Regional Water Quality
FlNA1JlODIOI3193/b1a
Control Board (RWQCB), concur with the
selected remedy.
3.0
ASSESSMENT OF THE SITE
AWIal or threatened releases of
hazardous substances from this site, if not'
addressed by implementing the response action
selected in this Interim ROD, may present an
imminent and substantial endangerment to
public health, welfare, or to the environment.
'4.0 . DESClUPI'ION OF THE REMEDY
Alternative 6, the selected remedy,
which addresses the primary risks posed by
soil coot:amin:ation (a principal threat at this
site) consists of the following components:
(1)
The site will be capped using a
minimum two-inch thick asphaltic
concrete cover, eJimin:atil'lg any
immediate threat by minimi:dng
transport via surface water runoff and
preventing ingestion, dermal exposure,
and inhalation of CODtamin:atM dust.
(2)
Any sediments in the ditches leading
off the site determined to contain
contamin:ants that pose health or
ecologic risks or are above five times
sediment background concentrations
will be excavated and placed under the
cap. CoDt:aminated soils will also be
consolidated at OU B 1 from the nearby
sites Potential Release Location (PRL)
29, Study Area (SA) 12, and SA 4. A
sediment trap will be installed in the
drainage ditch downstream from the
DRMO yard to collect any contami-
nated sediment transported by runoff.
1-1
-------
(3)
1be cap will substantially reduce
driving forces for migration of
CODtamin2nts to groundwater,
effectively eJimin2ting that exposure
pathway.
(4)
1be cap will be monitored aud
periodically repaired to maintain long-
tenD effectiveness, in compliance with
an approved cap operations aDd
maintenance program document.
(5)
Surface Water, vadose zone soils, soU
gas.' and groundwater wBl be
mOnitored under an approved program
to assure long-term cap integrity and
effectiveness.
(6)
SoU treatment technologies that offer
the potential of reducing toxicity of
COlJt3minalltS wBl continue to be
evaluated; technologies tested wBl
adhere to specific performance criteria
defined by reduction of potential heaJth
risk. An annuaJ repon of progress
wBl be prepared.
~
(7)
Prior to selection of a final remedy,
institutional controls, in the form of
use restrictions, will be invoked to
ensure that the area of OU B 1 will be
used only for industrial activities.
.~
1be selected alternative is coDSistent
with the criteria of interim remedial actions
and with the basewide remediation strategy
developed for McClellan AFB. The
alternative wi protect employees and site
visitors from heaJth risks and prevent further
migration of contamination whUe a final
remedial solution is developed. Therefore, the
alternative meets the criteria for interim
actiODS. 1be McClellan AFB remediation
strategy calls for 1) short-term actions that will
FlNAlJlODJOI31931ta18
successfully reduce significant threats to heaJth
and to the environment, and 2) continuing
development of cost-effective technologies to
reduce contaminant toxicity, mobility, and
volume as finaJ remedial solutions.
5.0
STATUTORY DETERMINATIONS
Set
ProtdvmaiS
The selected remedy is protective of
human heaJth and the environment. Protection
will be achieved at this site by capping
coutamin2ted soUs, thereby eliminatil\g any
immediate threat by preventing ingestion,
dermal exposure, and inhalation of
coutaminants in soils, sediments, or surface
water. InstitutionaJ controls wi be used to
ensure only industrial use for the capped area,
whUe a final remedy is being developed.
Groundwater resources are also protected by
this remedy.
5.2
Applicable or Relevant and
Appropriate Requirements
The selected response actions comply
with federaJ and state requirements that are
legally applicable, or relevant and appropriate.
5.3
Reduction of Toxicity, Mobility or
Volume Through Treatment
SOU containing greater than 10 parts
per mOlion (ppm) of polychlorinated biphenyl
(PCB) compounds will be capped, thereby
reducing the mobUity of site CODtamin~ion;
toxicity and volume of coDtatnination will not
be reduced untO a soU treatment technology is
selected and implemented. SOU containing less
than 10 ppm wUl also be capped. This more
extensive cap construction is planned to
improve the Defense Reutilization Marketing
Office (DRMO) yard for greater traffic loads,
1-2
-------
as opposed to INWinl a CERCLA c1euup
leva.
Tr~~ tecImololies for soD will
. continue to be evaluated. The sipers' of this
agreement commitment demoastrates their
inteDt to satisfy the preference to reduce
conumift2ftt toxicity, mobDityr or volume as a
principal demeDt.
5..
Use or PfI'1NNllt Soluti_,
Altematiye Treatmellt or Resource
RecoYIl'1 TM'.h~. .
1
Pei'maDent solutions IDd altemative
treatmeDt or resource reeDvery tecImoloJies
will be used to the maximum extent practicable
in the selection IDd implementation of a fiDal
soD tr-""--"t tec1mololY for OU 81. Durinl
evaluation, treatability study update reports
wUlaaauallJ assess the status of viable
treatmeDt tecImologies.
BecauR the cappiDI remedy wUl result
in hazardous substaac:a ~ininl on site
above hea1th-based levels, a review will be
conducted within five years after initiation of
the remedial action, IDd every five years
thereafter, to ensure that the remedy coDtiDueS
to provide adequate protection of human health
and the eaviroDlDeDt.
5.5
Cast ElrectiytDeSS
The remedy is cost effective beanse
maximum protection is achieved for Ihe
estim-IMI cost of performance. The analysis
contained in the FeasibDity Study aad Ibis
ROD demonstrates that additioDai remedial
action aDd the cost associated with that action
would DOt achieve a measurable reduction in
risk, but that less effort aDd a lower cost
would result in a measurably higher risk It Ihe
site.
J
A P. B B TT
D . uty for Hazardous Materials and Waste
Deputy Assistant Secretary of the Air Force
(Environment, Safety and Occupational Health)
71~eJ. m.J..r
J Wise I
. Ac:tiDg R.egioaal Adminim-ator
tJ .S. Environmental Protection Ageucy
. Region IX
:-~
/;} 1 /) -/' ,/
ll,,-, r~~ L:.. ~(~ .
-
Anthony J. LaDdis; Chief
Site Mitigation Branch
Department of Toxic Substances Control
Region 1
FlNALaODt'Onl93/b1a
.7.. #V? 9.:?
Date
9-:j -f3
Date
.
"
IJ- 2. 13
Date
1-3
-------
PART D. DECISION SUMMARY
This Decision Summary provides an
overview of the problems posed by the
"McClellan Air Force Base (AFB) Operable
Unit (OU) 81 Superfund site. It also includes
a description of the remedial altematives
considered. aDd ~e analysis of those
alternatives compared to criteria set forth in
the National Contingency Plan (NCP). This
Decision Summary explains the rationale for
the remedy seI~on and bow the selected
remedy satisfies the statutory requirements of
the Comprehensive Environmental R.esponse.
Compensation, and Liability Act (CER.CLA).
1.0
SITE NAME, LOCATION, AND
DESCRIPI10N
1.1
Site Name and Loaation
McClellan AFB
OUBI
McClellan AFB, California
1.2
Site Description
Operable Unit BI is located in the
southwest ponion of McClellan AFB. The
OU consists of an open storage lot operated by
the Defense Reutilization and Marketing Office
(DRMO), a former transformer storage, load-
ing, and unloading area, and the Civil
Engineering (CE) Storage Yard, and three
drainage ditches that receive surface water
runoff from the DRMO storage lot. The OU
is approximately 18 acres in size.
The area of OU Bl is relatively flat
and underlain by alluvial soils. Three ditches
drain OU B 1: two in the northern areas and
one in the southern area.
f1NALaODlO12I93/bu
1.3
Topograpby
The McClellan AFB facility is located
in the Sacramento Valley, approximately seven
miles northeast of Sacramento, C31ifomia.
The regional topography slopes gently
westWard toward the SacramentD River.
lA
Land1Jse
The on-base areas surrounding OU Bl
are industrial, warehouse, and aircraft opera-
tion areas. Off-base (within SOO feet), nearby
land is zoned residential and light industrial.
1.5
Location and FaciBty Layout
Figure 1-1 shows the location of the
site near Sacramento. Figure 1-2 shows the
current site features within the OU. The area
delineated as OU B 1 consists of four
previously identified sites and the area between
them: Potential Release Location (PRL) 29,
StUdy Area (SA) 12A, SA 12B, and SA 13.
Operable Unit 81 also includes the drainage
ditches that receive runoff from the DRMO
storage yard. Throughout this document these
locations will be referred to collectively as OU
B1.
1.6
Geology
The subsurface in the area of OU Bl
consists of alluvial sands, silts with minor
gravel, and clay layers.
From the ground surface to the top of
the water table (105 feet below ground surface
(BGSn, vadose zone deposits beneath OU Bl
consist of inter-bedded sands, silt, and thin
clay lenses, with a hardpan layer between 3
B-1
-------
aDd 8 feet BGS. These sedimeats were
deposited in a complex fluvial environment of
frequectly shifting streams on an alluvial plain
1bat resulted in laterally aDd vertically
discontinuous lithologic units. IrolH»xide
cemented hardpan layers indicate periods of
DODdeposition. Silt layers have carbon-coated
root casts aDd organic debris from plant
growth, which also indicate periods of
DODdeposition. Carbonaceous material was
reported in borings ffom 2 to 40 feet 80S. .
,
The water table beDeatb McClellan
AFB is typically 100 to 105 feet BGS aDd
varies locaJty because of topography and
depressions created by water supply wells.
From the water table to a depth of greater than
400 feet BGS" one aquifer provides water for
domestic aDd industrial uses in the vicinity of
McClellan AFB. Beneath OU Bl,
groundwater flows to the southeast toward a
pumping depr.ession created by McClellan
AFB and municipal supply wells.
The communities in the vicinity of
McClellan AFB receive potable water from
off-base municipal wells; McClellan AFB
obtains potable water from on-base wells. 1be
nearest well to OU Bl is Base Well IS,
located approximately 1,000 feet southeast of
OU B 1.
~...
FINAlAODJ072I931b18
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-------
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Bverta Road
,.
Rio
Unda
Bkhom Blvd.
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MAIN
'Ditches
BELL
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:.:.':.;.:.:.:-:.
jj!~~!~1;~~:~J
2
3
Scale in Miles
1oCOU81-OWi . _..IH.SAC
Figure 1.1. location of Operable Unit 81 at McClellan Air Force Base
FlNALROD/072.I93/bu
D-3
-------
45 MIL
tl>PE
lINER
,
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..
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'~;SA 128
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SA 13:
.. .. .. .. .. .. .. ..
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,
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.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
I'ADlNG 700
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.. .. .. .. .. ..
... .. .. .. .. ..
"-. .''';-0.-,
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250
SCALE IN FEET
LEGEND
DR~NAG£ DITCHES:
---.~ .r HORT"
NORT rv CENTRAL
- . SOU7ri
[I] PERFORATED srm PLNlKlNG
.. SC..J<: ALUMINUM PLANKING
D PAVEt /lAEAS
!LZI HOPE LINER
~ IORASS:..NID
D
au B1 BOUNDN'ty
.----,
. I
'-----'
LOCATIONS WITHIN OU B1
=I===F
RAILROAD 'TRACKS
~
CHNN LN
-------
2.0
SITE msroRY AND
ENFORCEMENT ACTIVITIES
2.1
Background oa ContamiDatioo
Problems at McClellan AFB OU 81
The area designated as OU 81 was
open farm land and residences until about
1957. A chronological history of the area is
shown in Figure 2-1. Building 700, which
borders OU Bl on the south and west, was
built in approximately 1962; the area northeast
of the building has been used as.ID open
storage lot by the DRMO since the early
19605.
~
In the early 19605, waste oil was
appl ied to OU B 1 soils to suppress dust. The
waste oil was collected from various facilities
on base. The oil may have consisted of
hydraulic oils, degreasing solvents,
.. .-transformer oils, and automotive oils and
fluids. Transformers were stored at the
DRMO lot at various times from the 19605
through 1987.
North of the storage lot along the
railroad tracks, transformers containing oil
with PCBs were loaded and unloaded from
railroad cars (SA 12B). The CE storage yard
(SA 13) has also been in use since the 19605.
MoSt of the materials stored at the yard were
nonhazardous; however, transformers contain-
ing PCBs were reportedly stored in the yard
so.me time between 1960 and 1987. By 1977,
the CE yard was paved with asphalt.
~..
In 1987, I.S to 7 gallons of PCB-
contaminated oil leaked from a transformer
onto the ground in the northern portion of the
DRMO storage lot. Contamin2ted soil in the
area was excavated to approximately 10
inches, removed, and covered with clean
gravel (Radian, 1991).
FINAlJtODlO72l931b&a
In 1992, during the OU B RI, PCB
connmination was reported in surface soil in
. the DRMO yard. A fence was constructed
around the soil area CODbini,,& at least 100
milligrams per kilogram (mglkg) of PCBs to
restrict access, and solid metal planking was
placed over the area to reduce fugitive dust
emissions (Radian, 1993). In 1993, a 45-mi1
HDPE plaStic liner was placed over the area YO
control dust and to prevent runoff to a nearby
drainage ditch. The fence and liner constituted
a time-aitical removal action to prevent
worker exposure and transport of PCBs and
dioxins in runoff. Access to the DRMO yard
was also restricted so that only adults could
enter.
2.2
Previous Studies
Previous studies at OU Bl include: a
1985 investigation to determine the presence or
absence of buried waste at PRL 29, a 1987
investigation to verify cleanup of an oil spill, a
1990 shallow soil gas investigation, and the
1991-1992 OU B RI. Objectives of the OU B
RI were to determine the presence or absence
of PCBs and other contaminants, to define
possible contaminant source areas, and to
collect sufficient data to conduct a health risk
assessment and an engineering evaluation of
remedial alternatives.
In a sampling effort subsequent to the
OU B RI, sediment sampling was performed in
drainage ditches receiving runoff from the
DRMO storage yard. The OU B I Remedial
Investigatio~easmili~SmdY~S)Report
(Radian, 1993) documents the distribution of
chemicals of concern and evaluates
technologies that could be applied to remediate
contaminated soils at OU B 1.
D-S
-------
1962
CtVU OMWEEMNC
STORACC YARD
1968
1993
LEGEND
OU BIKHffOARY
PERFORATED STEEL PLAMKM6
SOLD ALUMMl PLAMONC
PAVED AREAS
I I REMOVAL ACTION AREAS
CHAM UMOVARBED WME FENCE
CRCEK^RAMACC DITCH
RALROAO TRACKS
Figure 2-1. History of OU B1
FTNALROCV072I93/1UU Q^
-------
2.3
Regulatory and Eaforcemeat History
,
McClellan AFB was listed on the U.S.
Environmemal Protection Ageoc:y's (U.S.
EPA) National Priorities List (NPL) on 22
July 1987. At McClellan AFB, the Air Force
is the principle responsible party aDd the lead
agency for conducting investigative aDd
cleanup activities UDder CERCLA. em 02
May 1990, the Air Force, the U.S. EPA
Region IX, and the California EPA
Department of Toxic Substances Control
(CalIEPA DTSC) (known then as the
Department of Health ServiCes) signed an
Interagency. Agreement (lAG) for McClellan
AFB to ensUre that environmental impacts
from past and present operations are
thoroughly investigated and appropriate
cleanup actions are taken to protect public
health, welfare. and the environment. The
U.S. EPA, the CallEPA DTSC. and the
R.egional Water Quality Control Board
(RWQCB) provide regulatory oversight
consisting of teclmical support, review. and
comment on all investigative and cleanup work
at McClellan AFB.
Operable Unit B 1 is proposed to be the
first au to advance through the CERCLA
process at McClellan AFB because the
cont.amination poses a potential threat to the
environment and to human health should the
contaminants migrate into an exposure
pathway. The draft IUlFS Repon was
~bmitted in March of 1993, and the final was
completed on 02 July 1993.
:-...
FINALRODlO72l93/bu
D-7
-------
3.0
IDGIILIGHI'S OF COMMUNITY
PARTICIPATION
Remedial Project Managers from each
regulatory agency and from McClellan AFB
meet quarterly in what is mown . the
Technical Review Committee (TR.C). The
purpose of the TR.C is to review project status
aDd plmned ~vitlei. Public repraematives
from the County of Sacramento. the City of
Sacramento. and an on-base union also take
pan in the TR.C.
,
To suppon R.IIFS work at Mc:C1e1lan
AFB. a Co1pD1unity Relations Plan (CRP) was
developed in December 1985 and updated in
February 1988 and again in January 1991.
Community interest aad invotvement in
McClellan AFB's Installation Restoration
Program (IRP) has been continuous.
McClellan AFB holds public meetings on an
as-needed baSis. but at least twice per year, to
respond to community questions and concerns.
Since December 1987. a quanerly newsletter
bas been published. and several McClellan
AFB fact sheets have been developed to
explain technical aspects or upcoming activities
to the general public; the newsletters have
been mailed to approximately 2,500 members
of the surrounding community. Fact sheets
are distributed as needed.
.:'~
The community participated in the
Interim Record of Decision (ROD) through a
. formalized comment process.. Community
members received a fact sheet summarizing the
. Proposed Plan in April 1993. They were
encouraged to provide comment during the 30-
day public comment period, from 16 June to
16 July 1993. This comment period was also
announced through a public DOtice published in
the S/Jcrame1llO Bee. a daily newspaper of
general circulation. A public meeting was
held on 30 June 1993 at 7:00 p.m. at Bell
FINAlJlODI072I93/U1a
Avenue Elem~ School. A transcript of
this mNring is presented here as Attachment
B. Public comments were recorded. along
with responses. in the Responsiveness
Summary. The Summary is presented here as .
Attadunent A, aDd is also available to the
public at the AR. repositories. Attachment C
presents an index of the Adminim-ative
Record.
n-a
-------
4.0
SUMMARY OF SITE
CHARACTERISTICS
Based on their reported concentrations,
toxicity, aDd frequency of detection, the
following chemicals were identified as 16
chemicals of concern (COCS) for au Bl
(Table 4-1):
TABLE 4-1. CHEMICALS OF CONCERN
AT McCLELLAN AFB OU Bl
Arsenic
Benzene
Cadmium
chromium
Copper
1,l-Dichloroethene (1,I-DCE)
Congeners of dioxin and furan compounds
P Lead
Mercury
Molybdenum
The PCB Arochlor 1260
Selenium
Silver
Tetrachloroethene (PCE)
Tricb1oroethene (TCE)
Zinc
. The only PCB reported in au Bl was
Arocluor 1260. Therefore, in this. repon, the
term .PCB. refers to Arocb1or 1260.
4.1
Geology
-......
Operable Unit Bl is underlain by
altemati.ng discontinuous sands, silts, gravels,
and clays typical of the alluvial overbank and
fluvial deposits of the region (Figure 4-1).
The soils underlying the study area have
highly variable percentages of clay, silt, sand,
and gravel; stratigraphic contacts between soil
FlNALRODlO72l931t8&8
types vary from sharp to gradational in the
vadose zone (0 to 105 feet BGS) and shallow
saturated zone (105 to 400 feet BGS). The top
6 to 8 ind1es of soil consists mosdy of a
mixture of saud, silt, aDd gravels. A thin
hardpan layer is present beneath OU Blat
depths ranging from 3 to 8 feet BGS. This
hardpan layer, along with fine-grained
litboiogia, restric.u tbt vertical movement of
coftt2minlams.
The water table beneath au B 1 is
currently at 105 feet BGS, but during the
.19605, when the area was first used for open
storage, the water table was as shallow as 75
feet BGS. The water table has declined
approximately one foot per year.
Groundwater flows beneath McClellan
AFB from the east and is drawn toward
depressions in the groundwater surface created
by well pumping. In the vicinity of au Bl,
flow is to the south-southeast toward a regional
depression created by McClellan AFB and
municipal supply wells. Recharge of
groundwater by surface water at McClellan.
AFB is limited due to the extensive paving and
storm drainage system, and because of the less
permeable shallow hardpan layers that occur in
the vadose zone soils.
4.2
Contaminant SOurce Areas
The RI at OU Bl was focused on
surface and near-surface soils in the open
storage lot east and north of Building 700,
where 1,745 surface scrapes were collected .
and 68 soil borings were drilled during the RI
(Overlay A). One polychlorinated biphenyl
(Arochlor 1260), dioxins, furans, petroleum
hydrocarboas, volatile organic compounds
(VOCs), semivolatile organic compounds
(SVOCs), and inorganic species were reported
in au Bl soils, primarily in the near-surface
U-9
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OU B RI
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McClellan Air
Cross-Section
OU B1
LEGEND
Force
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Fill
Sand Lithofacies
Silt lithofacies
Cloy Lithofacies
Hardpan
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Power - Auger Boring
Hand Auger Boring
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. ..'. :';01. "~'l").~"~II(.~~':~'.(~:~t::~li :~ i:::
. 'o'
:.1,° .'~i :.1,'.':". :.~.. .t:i I :.1,':,:"" t :.1,':,':; t ~.11' .,':;. i.1 .f ':. o' ~i .,.~., ":"'Il,~,' .,:; I :.~.. ,':i :.,
1\1..,'" \",,".1 \1.."..I.\lo,,"r.,.\,...,...,.\I""i' ,.\Ii :.' '., I," ',\:"""r.1.\'i.,II' , \1,""r.1\'(
~-~....\.i;'\;':N~:\;::'II~:";::\II~:\ ::. ~:. :1 -::' :~~::;::M~::;:::I{~::
~. . .. . gg~ .'..'~.'..'.,.'
?
.
400
I
450
I
~zo
?
.
?
.
---------------------------------------
Location of Cross-Section
J ~ '-...lJ ... -'- ('
'""
.
.
-
000
~
.
~
to
.
.
.
.~.32.31..: .20 "AI
. -21
An . 22
50. .
.
.
.
..
I
D
I
I
~I)~
,
II
aa-
'-"
tI
13
.
. .
.
1
.....--'
r-
\1
500
I
550
I
AI
tQIOU
?
.
?
.
.".1' :11:',"",'
?
.
Figure
4-1.
Cross-Section
of au 81
A-AI
-------
areas. Based on results from soU samples
collected aDd analyzed. shallow soU
cont2mimation at OU Bl is widespread
laterally. but limited in the vertical extent.
4.2.1 PCBs and DioximIFUI"8DS
,
Soil - Widespread. low-level (less
than 10 mglkg) PCB comamift2tion in near-
surface soUs is present throughout the unpaved
areas of OU Bl (Overlay B). The waste oil
that was reportedly applied to the soU to
control dust during the 19605 probably
ac<:9W1ts for the' widespread low-level PCB
cont2min2t~n found at OU Bl. However.
subsequent surface water runoff may also have
contributed to the widespread cont2min2tion.
The highest concentrations of PCBs (500 to
240,000 mglkg) were reponed in the north-
west portion of the DRMO storage yard where
transformers were unloaded and stored.
Most of the PCB cont2mil'l~tion is
concentrated within the upper foot of soU. In
the area of highest surface soU PCB
concentrations. the vertical extent of PCB-
contaminated soUs is estimated to be 6 feet
BGS (Overlays C and D). No PCB-
contaminated soUs were reported below 6 feet
BGS.
:~~
Low-level dioxin and furan contamina-
tion in surface soUs is also widespread
throughout the unpaved areas of OU B 1
(Overlay E). There appears to be a
relationship between PCB and dioxin/furan .
concentrations in soU: as concentrations of
PCBs increase. concentrations of dioxin and
furan congeners increase. Several different
dioxin and furan isomers were reported; to
compare their toxicity, the international toxic
equivalency factor (l-TEF) method was applied
to convert the concentrations of different
isomers to an equivalent concentration of the
FIN ALRODlO72l93/tata
most toxic isomer. 2.3.7.8-tetrachlorodibeozo-
p-dioxin (2,3.7.8-TCDD). The 2.3.7.8-TCDD
equivalents (TCDDeq) are less than 1
microgram per kilogram (pglkg). except in the
area of highest PCB conumination. In the
area where PCB concentrations were the
highest (>500 mglkg). pentachloro-
dibenzodioxin (PeCDD) and pentacbJoro-
dibeomfuran (PeCDF) were reported in four
samples, but these could not be quantified due
to PCB interference.
Sediment - PCB cont2mination was
reponed in all three of the drainage ditches .
that receive ru~ff from OU Bl (Figure 4-2).
Concentrations decrease with distance from the
DRMO storage yard. from 470 mglkg in a
ditch at the yard to 4.2 mglkg at the point
where runoff enters Magpie Creek. Dioxin
cont.:aminRn was reported in samples
collected from the drainage ditches. No PCBs
or dioxins were reponed in Magpie Creek.
Inorganic species reported in ditch and
creek sediments were compared to subsurface
soU background concentrations because DO .
surface or sediment background concentrations
have been established. Arsenic (3.7 to 5.0
mglkg), cadmium (0.74 to 11.0 mglkg), lead
(21 to 180 mglkg), and zinc (70 to 330 mglkg)
were the inorganic species moSt frequently
reported above subsurface soil background
concentrations in drainage ditch sediments.
Cadmium (3.6 mglkg) and lead (11 mg/kg)
were reported above background in only one
Magpie Creek sample.
Surface Water - Surface water grab
samples were also collected from the drainage
ditches by McClellan AFB Environmental
Management staff (10/29/92 and 12/09/92) and
the Regional Water Quality Control Board
(RWQCB) (12/21192) during three storm
events between October and December 1992
D-ll
-------
6
N
i
;
~
;:
!:
SS03H028
PCB (0.5) NO
TCDDeq (0.5) NO
GROSS IlETA(0.51 24
1C05H288
PCB (0.51 5.4
TCDDeq (0.5) 0.007
CADMI~ (0.5) 4.1
LEAD (0.51 180
SELENIUM(0.51 0.5
71NC (n.~1 130
.. .
SS03H027
PCB 10.51 ND
CAOS5 BETA/D. 51 27
1C05H287
PCB 10.5) 2.8
CADMIUM (0.51 2.8
~EAD (0.51 29.0
ZINC 10.5199.0
D RI SEDI€NT ~ LOCATION
. ~ LOCATION FIIOM PIIEVIOuS ..vtsTIGATION$
... ST_"TDI IILtIOFF F'l.Ow DllECTIOH
lID NOT OE1ECTED MOVE IIEPOIfhIG LMT
DIIAHAGE DIT~
~'"'WoI,.;~ HClATH
-THlC£H1RAI.
.-;..... SOUTH
./
WS21
CADMIUM (0.5) 0.7
LEAD (0.5) 13
PHENOL (3) 0.2
I SAWPlE LOCATION
CDNTAMINANT \~Aftff) DEPTH
I
AESUL T "
IN mg/kQ
~
~
~-
.~r-
I fIB
NOTE' DIOXIN RESIJ. TS.. ~kO OF TCDD EQUVALEHT
ICOSH286 .
PCB 10.51 20 I
TCDDeQ (0.51 '0.02 I
CADMIUM 10.51 7.0
LEAD 10.51 54.0
ZINC 10.5) 330
CYANIDE (0.5) 0.31
10.51 2..
10.5) 16
(0.5) 0.42
10.51 57
(5 I 2.9.
151 I'
1COSH282
PCB (0.5)
TCDDeQ 10.51
ARSENlcrO.51
CA!lNIU!C10.51
LEAD 10.5)
ZINC 10.5)
.-.--- -
1C05H28S
PCB 10.51 20
AASENIC(0.5) 3.7
CADMIUM.0.5) 8.6
LEAD 10.5) 63
ZINC (0.51320
1C05H284
PCB (0.51 15
BARIUM 10.5) 620
CADMIUMIO.51 8.2
LEAD 10.5 I 34
ZINC (0.51 310
PCB (0.5 I '9
0551071
PCB (0.51 31 .
1C0550432 ,...,{...
PCB 10.51 470 ~
1C05H263
PCB (0.51 18
CADMIUM (D.5) 11
LEAD (0.51 42
ZINC (0.5) 330
L
WS211
TOTAl CYANIDE 10.5) 14
CADMIUM (D.51 13
LEAD eO.51 28
ZINC 10.51 320
=
~
PSUH03
PCB
PCB
1.1.1-TCA
TOTAL CYANIDE
SOCI
1C054281
PCB 10.5) NO
ARSENIC 10.51 5
CADMIUM 10.5) 1.3
LEAD (D.51.2
5ELENIUMIO.51 0.5
ZINC 10.51 180
ODO (0.510.05
OOE 10.510.04
DDT ID.5)0.10
1COSH260
PCB (0.5) ND
TCODeQ 10.51 0.00D3
AASENlceD.513.9
CADMIUWIO.5) 0.74
LEAD 10.5) 21
ZINC (0.5) 70
DDE (0.5) 0.0.
DDT (0.5 I 0.13
SCA.E .. F'EET
Fi('mrf~4. '.I
~'~Id'm::.:;nt !>.,,: ;l";G!~, l " ""::!\-;"'c.
(-,l l t==:":
-------
before the HDPE liDa' was placed over soils in
OU B 1. Samples were collected from five
locations originating at au B 1 aDd eading
where the drainage ditch empties into Magpie
Creek (Figure 4-3). Not alllocaUons were
sampled during each storm event. In the
figure, 8NS. means the location was DOt
sampled during that event. An 8HR. indicates
DO contamin:llnt$ were reported above detection
limits. Based on the data collected for the
three storm events [m some cases with just one
sampling location), the following conclusions
were reached:
.
Surface water runoff from the southern
part of OU Bl is not cont2min:llte(l
with PCBs, dioxins, or furans
(sampling location EM-3).
.
Surface water runoff from the northl
centtal ponion of OU B I, which in-
cludes the area of highest PCB concen-
ttations, contains the highest concen-
trations of PCBs (190 "glL) and
dioxins (829 picograms per liter [pglL]
TCDDeq) in the runoff (sampling
location EM-S).
,
.
Surface water collected from 500 feet
downstream of OU B 1 contained PCBs
(83 pglL) and dioxins (535 pglL
TCDDeq), which are about half the
concentrations reported at the DRMO
storage lot (sampling location EM~).
.
Polychlorinated biphenyls were not re-
ported in surface water collected where
the drainage ditch flows into Magpie
Creek. Dioxins were reported at the
detection limit (0.45 pglL TCDDeq)
(sampling location EM-8).
The samples which led to the above
conclusions were taken prior to the
FlNAUtODI072I93/tau
emplacemeat of the proteCtive synthetic liner
over soils in OU B 1. Analytical results from
samples collected ~y the RWQCB after liner
emplacement indicate that PCB concentration
in runoff' from the DRMO and the associated
ditches bad decreased.
Groundwater samples have not been
collet':tOO fur PCB. dio:tin. or fr.mm analysis in
mo~ wells downgradient of OU B1.
However, it is unlikely that the groundwater Is
cont:llminmoo with PCBs, dioxins, or furans
because the vertical extent of contamirnttion
determined by soil sampling is 6 feet BOS in
au Bl, and these compounds are not likely to
migrate to groundwater (Section 4.3.4).
Therefore, it is unlikely that au Bl is or will
be a source of groundwater contamination.
4.1.1 Petroleum Hydrocarbons
Petroleum hydrocarbon (motor oil and
heavy hydrocarbons) contamination is wide-
spread in au B 1 surface soils at
concentrations less than 100 mglkg (Overlay
F). The widespread contamination is most.
likely due to the spraying of waste oil on the
soils to control dust in the l%Os.
Concentrations of petroleum hydrocarbons
from 3,400 to 8,700 mglkg were also reponed
in surface soils in the area of highest PCB
COtl~[J1iQation. This cont2mination was most
likely discharged from transformer leaks or
spills.
Petroleum hydrocarbons (motor oil and
heavy hydrocarbons) were also reponed in soil
samples from 1 to 4 feet BGS in au 81
(Overlay G). The highest concentration (300
mglkg) appears to have been discharged from
a surface spill. The vertical extent of
hydrocarbon contamirnttionis not defined in
two shallow borings, where concentrations of
300 mglkg and 130 mglkg. respectively, were
D-13
-------
.'~~
N
\0: SAW-LING EVENT
".
l SAllPll HG 29 OCT 92 09 DEC 92
LCCA1JDN pca TCODeq PCB TCODeQ
( EM-3 NS NS NR NR
E~ NR NS 13.6 1.26
C:: 9 0.61 20... NR
NR NS 16.1 0.6
EM-8 NR NS NR 0.45
21 DEt 92
pca TCODeQ
NS NS
83 535
190 829
NS NS
NS NS
. EM SURFACE wATER SAMPL£
PCBs In ~O/L (PPb)
TCOOeq In POlL (PDQ)
! NS = NOT SA""LED
( NR - NOT REPORTED' I. e.. NOT DETECTED)
~~
,.
"
I
I
-
I
III ]j
II!
, ~.-
-
~
a
~ [-
I ro
I ~
-
..
13
LEGEND:
EM-4
.... STORMWATER RUNOFF FlOW DIRECTION
DRAIN.:,.:;:: DiTCHES:
au 81
NORTH
NORTH/CEf'o.'TRAL
t'':-:.-:.-,.-~~
~~ SOUTH
~;. .
~
o
,
500
,
~~
( )\[
o]l""1~rf1M~
SCALE IN FEET
Figure 4-3. Surface Water Sa~ling Locations
in OU 81 and Drainage Ditcnes
FINAUtODlO716931b18
11-14
-------
reported in samples collected from the bottom
of Uch shallow boring .(3 feet 80S). In other
areas. petroleum hydrocarbon conceottations
decrease to much lower values over short
vertical distances (3 feet).
4.1.3 'Semivolatile Organic Compounds
Semivolatile organic compound con-
t2min:ttion was also reponed in the area of the
PCB aDd petroleum hydrocarbon contamina-
tion. l.2.4-Tricblorobenzeoe (1.2.4-TCB) was
reported at con~trations as great as 69
mglkg in the area of highest PCB
concentrations. This SVOC is commonly used
to thin transformer oils and was most likely
discharged through spills or leaks of
transformer oils. Polynuclear aromatic
compounds, that occur in waste oils as by-
productS of combustio~ were reponed at
concentratio~ less than 3 mglkg.
4.1.4 Metals
In surface soil samples, ten inorganic
species were reponed above background
concentrations for subsurface soils throughout
OU B 1. The widespread distribution of
cadmium, lead, selenium, and silver in surface
soils suggests that inorganic constituents were
DOt discharged in separate spillS. This
distribution may have been caused by the
application of waste oils and/or traDSpon by
surface water runoff. Cadmium and selenium
are common trace constituents in fuel
. hydrocarbons. Lead may accumulate in waste
oils from engines using gasoline, and silver
was commonly used as an engine bearing alloy
(ATSDR, 1989-1990).
In subsurface soil samples, only tWo
inorganic species were reponed at five times
greater than background concentrations for
subsurface soils (McClellan AFB, 1993).
F1NAlJtODI071I93/bu
Concemntions greater than five times
bactground are considered high enough to
evaluate potemiaI risks. Concentrations less
dIaD five times background are DOt considered
ItItistically significant and are DOt used in risk
usessmem calculations. Selenium and/or
silver were reponed at five times greater than
subsurface b3ClcgroW1d concentrations in six
borings. The mm:imum concentration of
selenium was 22 mglkg in Boring 41 at 8.7
feet BGS. The maximum concentration of
silver was 3.0 mglkg in Boring SO at 10 feet
BGS.
Inorganic species reponed in ditch and
creek sediments were compared to subsurface
soil background concentrations because no
surface or sediment background concentrations
have been established. Arsenic (3.7 to 5.0
mgllcg), cadmium (0.74 to 11.0 mg/kg), lead
(21 to 180 mgllcg), and zinc (70 to 330 mgllcg)
were the most inorganic species frequently
reponed above subsurface soil background
concentrations in drainage ditch sediments.
Cadmium (3.6 mg/kg) and lead (11 mg/kg)
were reponed above background in only one
Magpie Creek sample.
4.1.5 Volatile Organic Compounds
Low concentrations (100 JLg/kg) of
VOCs were reponed in OU B 1 soils. Distri-
bution is limited to small noncontinuous areas.
This distribution of widely-spaced low
concentrations suggest that the VOCs were
. discharged from separate, minor surface spills.
Low-level cont:.mination in one boring is
present from 32 to 95 feet BGS.
Concentrations of the VOCS generally increase.
toward the water table, indicating that the
contamination may be residue from contami-
nated groundwater that historically flowed
beneath au Bt at depths less than 100 feet (75
feet BGS in the 1960s).
netS
-------
VolaliIe organic compouDds were
reported in soU ,as in the DOrthem portion of
OU Bl. The VOCs are DOt widely
distributed. The highest concentrations found
were at 21 feet BCiS: greater than 100,000
parts per billion by volume (ppbv) of
halogeuared VOCs (HVOCs) (fCE, PCE, cis-
1,2-DCE). These concentrations were only
reponed in one boring. Soil gas
concemrations at 21 feet 'BCiS decrease with
horizontal distance from this boring. Soil gas
concentrations also decrease with depth. In
one boriDg~ DO HVOC concentrations were
reported in soil 'gas samples collected from 30
to 60 feet ~S. However, at 81 feet BGS,
HVOCs were reported at 11,600 ppbv. This
suggests that there are two sources of soil gas
contamin~tion: small surface spills and residue
from groundwater cont2min2tion.
,.
4.3
Transport of Site Chemicals
4.3.1 Contaminant Properties
The potential for transpon of contami-
nants in the environment is largely determined
by the chemical and physical propenies of the
contaminants.
The properties that affect the ability of
the cont2min.aQts in OU Bl to be transported
(mobility) in a pathway are vapor pressure,
solubility, Henry's Law Constant, and
panitioning coefficients. These properties are
listed for the most frequently reported and
potentially hazardous contaminantS in
Table 4-2.
Vapor pressure indicates the potential
for the cont2min.anu to enter the vapor phase
from the liquid phase in soils and to be
transported in soil gas. The VOCS, with
higher vapor pressures at 2S degrees celsius
(C), have greater potential to enter the vapor
JINALRODI072I931ta&a
phase than PCBs or dioxin and funD
compouDds. Of the inorganic species, only
metallic mercury, if present in soils, would,
have a measurable vapor pressure at 2S C.
Aqueous solubility indicates the
maximum concentration (ID pgIkg of water)
that the organic compounds or inorganic
species can attain at 2S C. S.urface or
groundwater in contact with liquid, solid, or
vapor phases of any of the contaminants listed
in Table 4-2 can dissolve the cont2min~nt up
to this limit at this temperature. Solubility
limits for inorganic constituents are shown as
broad ranges because the compounds in which
they occur have DOt been identified, and the
aqueous solubility of each inorganic species
depends on the specific compound or organic
complex it has formed in the soil.
Henry's Law Constants (H) are indica-
tors of the behavior of the organic contami-
nants when their vapor phases are in' contact
with water in the soil. Higher values of H
indicate which cont2mipants are more likely to
panition to the vapor phase after being
dissolved in water. The H values are most
indicative of exchanges betWeen vapor phases
in soil gas and subsurface water.
The solid phase partitioning coeffi-
cients, Koc and ~, in Table 4-2 are indicators
of CODt211)inant properties that decrease the
mobility of COOt2minants in liquids. Inorganic
species may adsorb onto organic material or
inorganic mineral grains (clays or iron oxides)
in soils. Adsorption to soil grains can bold
contaIninVits in soils even though surface or
groundwater that has DOt reached the solubility
limit is moving through the soils. Solid phase
partitioning retards the movement of contami-
nants in the liquid phase. However, if the soil
grains are transported by water or wind, the
B-16
-------
adsorbed COnt2min:ants will also be
traDspOned.
The relative persistence of the
CODt2min:ants in the environment is indicated in
the last column of Table 4--2. Of the
CODt2min:ant~ in au Bl. the PCB. dioxin. and
furan compounds having the most chlorine or
fluorine atoms in their struCtUre art the most
persistent. All inorganic species are persistent
because they are DOt transformed or
mineralized. in spite of changes in their
physical or chemical state.
4.3,2 Transport Mechanisms
This section discusses the transport of
site and the factors that may have influenced
chemical migration.
,
The principal meclt2nisms that may
affect the movement of CODtamin2nts in au B 1
are shown. schematically in Figure 44. Table
4-3 summarizes the COCS affected by each
mechanism, propenies limiting mobility, and
pathways potentially impacted by each
mechanism in au Bl under current concH-
tions.
Volatilization - Volatilization is
considered to be a potential transpon
mechanism possibly resulting in the loss of
organic vapors in shallow soil to the
atmosphere. Although PCBs have vapor
pressures 100,000 to 1,000,000 times lower
than VOCs reponed in the soils of OU Bl,
PCBs in surface soils are locally 5,000 to
2,400,000 times more concentrated than
VOCs. Therefore, volatilization is considered
a transpon mechanism for Arocb1or 1260 in
OU B 1.
All organic compounds in OU B 1
soil may enter the vapor phase and migrate by
FlHAUODI071I93/b1a
diffusion or density~ven advection in soil
gas. Vapor phase COnt2min.ants have the
potential of migrating ~ the soil surface or to
gr:oundwater. 1be concentrations of organic
compoUDds in soil gas at the soil surface are
likely to be diluted by dispersion in the
. pathway. This mecb:anism would allow COCs
to emer the air pathway at low concentrations.
. Dissolved Aqueous Tramport -
IDorganic species aDd VOCs are more soluble
in water than Arochlor 1260 and would be
transported more readily by water in the
vadose zone or the saturated zone. Volatile
organic compounds have lower Koc and Kct
values (numbers representative of a
compound's tendency to attach to soil organic
particles instead of dissolving in water or some
other solvent) than PCBs, dioxins, or inorganic
species and do not strongly adsorb to
particulate matter. Polychlorinated biphenyls
and dioxins do not readily dissolve in water
and strongly adsorb onto soils.
Very low aqueous solubilities of the
more highly concentrated organic COCS and
the tendency of all COCs to adsorb to organic
material suggest that the total mass of COCS
transported by this mechanism from OU B 1 is
much less than the mass transported by
colloidal or fine particle transport. The
potential for surface water transpon by this
mech2ni~m is greater than the potential for
groundwater transport.
ColloidJPartide Transport -
Colloid/particle transport could be a potential
mecb2nism for facilitating migration of PCBs
at the site because PCB Aroclor 1260 has a
high K..:, and thus strongly adsorbs on soil,
colloids, and other particulates. Analytical
data from sediments downstream from OU B 1
indicate this meclulni~m is active.
D-17
-------
'¥
2 .
~ TABLE 4-2. MAXIMUM CONCENTRATIONS AND PHYSICAL AND CHEMICAL PROPERTIES (AT 25 C)
OF CONTAMINANTS OF CONCERN IN OU BII
a Solid Phase
~
i Maxim..... PlrtJtionh. . Ht!IU'J'. Law
Concmtntion ReporCed Vapor CoeOidents COMQant
In Soli or Soil Gu Prasure Aqueous Solubility K.eor~ ( ClIL In 181) Rtlati,e
(palka) (mm HI) (pg/kg) (L/Ka) ,., in w.ter PtnIstmee
ORGANIC COMPOUNDS
PCB Arochlor 1260 2.4 It 101 4. I Jl 10.5 27 6 Jl 10' - I Jl 101 0.013 P
Dioxin Congeners
TCOO 1.0 7.4 I 10.10 1.9 it 10.2 1.6 Jl 10" 7 Jl I~
PCOO 1.45 <7.4 Jl 10"10 <1 "10-4
H.OD 1.8 < 7.4 Jl 10"10 4 Jl IO"J c > 1.6 Jl 10' <11 10-4
HPCOD 3.38 <7.4 I( 10"10 2.4 I( 10-J c > 1.6 . 10' <7 Jl 10-4
= OCOO 10.9 <7.4 I( U)"IO 4 I( 10-4 c > 1.6 I( 10' <11 10" P
' TCOF 11.8 5.4 I( 10-' d 4.2 I( 10-1 c 3.5 I( lot - 4 I( 101 2.3 I IO"J
....
00 PCOF 19.1 <5.4 . 10-' >3.5 I 104 - 4 1 101 <2.3. IO"J
HI(COF 20.9 < 5.4 Jl 10-8 8.2 1 10.J c > 3.5 I( 104 - 4 1 106 <2.3 I 10"'
HpCDF 7.8 <5.41 10-' 1.4 Jl 10.J c >3.51 104 -.. 1 10' <2.3 x Ut'
OCDP 6.23 <5.41 10-' 1.21 10"' c > 3.5 It 104 - 4 It 10' <2.3 II IO"J P
I,t-DCB 9,100 ppbv 600 2.2.5 It 10' 65 1.42
Beor.ene 37 ppbv 95.2 1.8 1 to' 83 0.23
TCB 72,000 ppbv 51.9 1.1110' 126 0.38
cis-I,2-DCB 17 ,000 ppbv 208 3.5 1 10' 72.4 0.32
PCB 30,000 ppbv 17.9 1.5 1 10' 364 1.2.5
(Continued)
-------
'"
~
I TABLE 4-1. (Continued)
Solid Phase
PartitJonf.. HenrJ's Law
i Maximum Concentration Vapor CoeO'idenis Constant
Reported in Soil Pres.!lure Aqueol1'l Solubility K.or~ ( ~Ingu) Relad,e
(mg/kg) (mm Hg) (pg/kg) (L/Kg) III In water Persistence
INORGANIC SPECIES
Arsenic Species 47 N/A 0 - 302 X 10" Strongly sorbed. ',. N/A
Cadmium Species 49 N/A 0 - 1.4 X 10' , Sorbed to orpnic N/A P
material; fonns mobile
aqueous compleles. ',.
Chromium Species 590 N/A Cr+6 40 - 238 X 10" Cr VI reduced 10 Cr N/A P
Cr+3 0 - 1201 10' , III by Fe II and .
organic material; Cr III
sorbed/complexed by
= organic material. I,"
I
- 2.3 x 10-3 , 0 - 2 x 101'
10 Mercury Species 7.5 Strongly ~rbed 10 N/A P
(Hg metal) organic material.".
Lead Species 2,500 N/A 0 - 4.2 x 104 ' Strongly sorbed to N/A P
organic material.".
Selenium Species 52 N/A 0 - 1.1 x 10' ' 5.9 - 14.9' N/A. P
Silver Species 74 N/A 10 - 100' MIA P
. Values from Hazardous Substances Data Bank (1992) or U.S. EPA
(1986) unless otherwise noted. .
b Value estimated from log Koc ... 0.544 log Ko. + 1.377 (Kanega
and Ooring, 1980). .
C Values from Friesen, Villta, and Muir (1990).
d Value estimated from Henry's Law constant and aqueous solubility.
e Value estimated from log Koc I:: 0.72 log Ko. + 0.49
(Schwarmtbach and Westall, 1981).
, From Toxicological Profiles (ATSDR, 1989a, 1989b, 1989c, 1989d,
1990, 1991).
. From Palmer and Wittbrodt (1991).
b No K value found.
J
Koc tI:I Organic CarbonlWater Partitim Coefficient
K.t ... SoillWater Partition Coefficient
Llkg ... Liters per kilogram.
mmlHg =- Millimeters of mercury.
N/A ... Not available or not applicable.
P = Compound or inorganic species will persist longer than
other COCs of the same type.
pglleg ... Micrograms per kilogram.
pg/L =- Micrograms per liter.
-------
Airborne
Particle
Transport
Vapor Transport to Air
Surface
0.5 ft. - -
8
45
«_
3
CO
I 1.0ft.
-------
'"
~
, TABLE 4-3. MECIIANISMS OF COC TRANSPORT IN OU Bt
I I 'Pathways Pathways Know8
~ Mechanism COCs Mobilized Mohility Limited By Potentially .lmpacted Ie be Impacted
, V olatilizalion VOCs SurflCe air
PCB Arochlor 1260 Low vapor pressure
DiO](ins/furans Low vapor pressure Oroundwater
Bulk flow (nonaqueous PCB Arochlor 1260 High liquid viscosity; high Orounclwaler
phase transport) adsorption
Dissolved aqueous transport VOCs High Henry's constant SUffICe water
Inorganic species Absorption
PCB Arochlor 1260 Low solubility; adsorption Groundwater (mi.ratioa
= DioJdns/furans Low solubility; adsorption from another source area)
N
- Colloidal/fine (0.01 to 5 PCB Arochlor 1260 Water now velocity (or Oroundwaler SurfIce waler aedimeats
micron) particle aqueous Dioxins/furaris larger particles
transport Inorganic species
Airborne particle transport PCB Arochlor 1260 Surface covering; wind SuffICe air
Diolins/furans speed .,-J
Inorganic species
Cosolvent effects PCB Arochlor 1260 Volume and concentration Oroundwater
o( cosolvent
Preferential Pathways All in liquid or vapor Soillension and capillarity SuffICe air
o round water
COCs .. Contaminants of Concern
Koc ... Organic carbon/water partitioning coefficient
PCB.. Polychlorinated biphenyl
VOCs = Volatile organic compounds
-------
CosoI.ent meets - Cosolvem effects
are a potential Q'eCJulni~m for transporting a
PCB at 1he site becaI'~ PCB Aroclor 1260 has
a bigh affinity for some bydroCarbon solvents.
Although Archlor 1260 may have initially been
transponed to depths of 6 feet due to cosolvent
effects, it does DOt appear that solvents can
have any current effects on the transpon of
Arc:hIor 1260 in the vadou mne. The
eabancement of migratioD by cosolvency
requires concemrations of 1 ~ or more of
suitable solvent. The greatest solvent
concentration in, soils in the area of bigh
Arochlor 1260 concentration was 69 mglkg of
1,2.4-trichlGrobenzene. This concentration is
one thousand times less than the concentnnon
needed to increase transpon of Arochlor 1260.
Therefore. this mechanism is DOt actively
transporting Archlor 1260 to groundwater
beneath au B1.
~
Airborne particles - Fine soil
particles are present on the surface of the PSP,
solid aluminum planking. and uncovered soils.
These panicles may carry adsorbed COCS
from the soils covered by planking. Under
cuaent conditions in au B 1. equipment
operation. vehicle traffic, and winds cause fine
soil panicles to rise into the air transpon
pathway.
Bulk Flow - This mechanism is
unlikely to have any impact on the
groundwater pathway beneath OU B 1.
Evidence from subsurface sampling and
. analysis indicates that PCBs bave penetrated DO
more than 6 feet below the surface. The
historical practice of unloading and cleaning
transformers bas been discontinued.
Therefore. Aroclor 1260 is unlikely to migrate
to greater depths by this mechanism. Soils
deeper tban 6 feet BGS may have been
penetrated locally by the bulk flow of -
transformer fluids.
FINAUlODlO71l931b1a
Preferential Pathways - A
prefer~ pathway is a more permeable
pathway through the subsurface. These
subsurface features may consist of plant root
bores through fine-grained layers or cracks in .
cemented hardpan layers. Cont2min2ted
liquids or soil gas may be transponed in the
vadose zone more quickly through these root
bores or cracks than they would through pores
in fine-grained soils. However, root bores and
cracks are DOt present in each fine-grained
layer and. therefore, are DOt continuous
through the vadose zone. Preferential
pathways are more likely to increase the rate
of cont2min3nt mipion in soil gas than the
rate of liquid migration because of tension and
capillary forces acting on liquids in the vadose
zone.
4.3.3 Persistence
without the implementation of
remedial measures. CODt2min3nts in OU Bl
may persist. or be degraded by natural
processes. Highly chlorinated PCBs (e.g.,
Aroclor 1260) are relatively resistant to .
biodegradation under aerobic conditions.
Petroleum hydrocarbons can be biodegraded
by aerobic bacteria that exist naturally in the
soil of OU B 1. Biodegradation of chlorinated
VOCs is unlikely to occur under oxygen-rich
vadose-zone conditions, but it wilt occur very
slowly under saturated conditioDS. Oxida&ion,
bydrolysis, and photolysis of PCBs. petroleum
hydrocarbons. VOCs and SVOCs are all .
generally insignificant processes in natural
environments.
4.3.4 Transport Pathways
Site conditions and the distribution of
COCS in au Bl indicate tbe transpon mecha-
nisms that may be active and the transpon
pathways that are likely to be complete. The
U-22
-------
site coDditions aDd COC distributions that
iDdicate complete aDd incomplete pathways are
provided in the following discussions of
surface, subsurface, aDd grouDdYiater
transport.
Potential for Surface Tl'8mport
Two surface transport pathways, air
aDd water, have been i~1"ted by COCS from
au 81. Approximately 27~ of the soU sur-
face area has remained ~vered since COCS
were discharged; therefore, the surface
transport pathways have been open to the
COCS in s9rface and near-5Urface soUSe
,
Surface soil analytical results indicate
that Aroch1or 1260, arsenic, cadmium, chrom-
ium, lead, mercury, selenium, and sUver are
widespread and present in greater concentra-
tions than other COCS. Dioxin and furan
congeners are widespread in surface soUs, but
are present at one one-thousandth to one one-
billionth of the concentration of other COCs.
Volatile organic compound concentrations
were reported in subsurface soils; however,
they may impact the surface air pathway by
upward migration of vapor in soil gas.
Surface Air Transport Pathway -
The COCS in soils of au 81 are entering this
transport pathway. Vapor concentrations at
the soil surface are very low, but may be
emitted into the pathway over 30 years or
longer.
Vapor concentrations of approximately
6 i 1
-------
) .\f; .). . . . . . . .~. . . . . . .
... SI... .... "'.
,...............~...:.;. "..' "'. ~
:: - ~=...~...~::..~.:'..~..~.~....~.~~.~:'::.:~:::~.~~.-. .t~~.~.~~ ..~ ~':~':;.~...~
-J . .~. .
-:1 "".'~~- :"''':~::'~:'';:::::I.:+~;;;!.::~~~::+:':':~'f:' ;'~.?f::':~i'~~'~~~:~J~j~~
UaD
............ .
.
-
.~
-,
~ it
1
."'.....'.'
. .
. .
.: : ~
. .
:;-: '..::....... .......':.............
c
250
.
r
.1 ('I, r
SCA1.E IN FEET
..
N
I
i
~i 3, ~
. c- ..
.e:-
: .: i 2.
i:-- .
I j :; H H~-~~~~ m
!
!
s........:e. Sacr.- Co,.rwy Wale< ~ DMsion
.0 ..... ....
.."......................
. .. ... ....'
'i 30
j:
a:~20
..E
~- 10"
0'==:~~~~~~-8~--.~'.'
=~~:~~~r~8~8C.8.~*
y..,
(From July 1 to J.... 30)
Montl'l
Figure 4-5. Physical Features of au 81
FINALRODI07I 693/katl
11-24
..
SA
E
U.
.
17.a
CIUoI
luo,
Scuca: Surl8r:eWind Sumwy. McCI8IanAFB.'84HII67
. ...-...,...
'~~~"~I
LEGEND
D
OU B1 BOUND.-RY
,:- -;--:1
I I
,~_.:_..:'
100 YE.-R FLOOD PLAIN
.
DIRECTION Of SURF ACE FLOW
- «J- SURFACE CONTOUR U'IE N{f)
El£VATION (msI)
- ...-
~MlAGE
BUI1..DINGS. ROADS. FENCES.
RAILROAD TRACKS
...............
0U8R18 OUB1W.C SAC
-------
deposited IS dust on the PSP IS water in
depressioDS evaporates, or carried bact into
surfaee soil with infiltration. Silt- and clay-
sized (2 to 10 micron), COC-cont.:llmiftStM
particles settle out of the runoff IS rainfall
subsides and stream energy decreases. The
finer, conoidal particles remain suspended and
are transported a greater distance, reentering
the soil only where the runoff collects and
evaporates or infiltrates soils in the stream
bed. Thel'e are data to indicate that this
ma2ni~m is active in OU B1. Analytical
results from stream sediment samples collected
downstream from OU B 1 indicate that
~orl~,dwxiDS,~wm,~~
and lead have been transported in runoff.
The very low aqueous solubilities of
organic coes and the teDdenc:y of all coes to
adsorb to organic material suggest that the
total mass of-Coes transported as a dissolved
aqueous phase is much less than the mass
transported by colloidal or fine particle
transport.
The potential for surface transport of
coes in the soils of OU B 1 would be reduced
if a low permeability COVel' were placed over
contAminated soils. The placement of the
cover would diminish the potential for
exchange between soils and surface transport
pathways.
Potential for Subsurface Transport
Subsurface transport of coes in OU
B 1 is controlled by the downward migration of .
surface water, soil gas advection, and soil gas
diffusion. Surface covering over 73~ of.the
area of OU B 1 increases rainfall runoff,
decreases the average percent soil saturation,
aDd decreases potential for downward subsur-
. face transport of liquids containing COCS.
Conversely, soil gas diffusion and advection
FlNAlAODI072I93/b1a
are increased in soils with toWel' percent
saturation because thel'e is a greater percentage
of air-filled volume through which vapors may
migrate. The vapor phase of Coes in OU Bl
migrate IDOre readily through soils in the
unsaturated zone when percent saturation is
relatively low t and liquid phase coes migrate
more readily v.-h~ per~. ~ratiOD is re1a-
tively. high.
Downward migration of coes in
liquids beneath most of the OU B 1 area is also
limited by the physical properties of surface
aDd subsurface soils. Soil borings in OU Bl
indicate that cemented hardpan aDd S- to 15-
foot thick silt layers impede downward
migration beneath the site. A coDduc:tivity of
o to 7 x 10'" meters per second (mls) has been
assigned to surface soils IDd hardpan of the
type UDder1yiDg OU B1. Subsurface silt layers
are estim:atecf to have coDduc:tivities of I x 10-'
to I x Utn mls under unsaturated conditions.
The presence of root bores or c:rac:ts in fine-
grained layers or hardpan increase soil gas
permeability but increase the average water
conductivity of the vadose zone to a lesser
extent. Assuming a conservative average
conductivity of 2 x 10-' mls and a potential
gradient of 1, surface water carrying coes
may not reach the saturated zone (currently
105 feet below surface) within SOO years.
This very slow rate of migration applies to
most of the area of OU B I, where saturated
coDditions are unlikely to oc:c:ur because
surface coverings reduce infiltration aDd
increase runoff.
In the northeastern portion of OU B 1,
TCE, PCE, I,I-DCE, cis-l,2-DCE, aDd
benzene have been reported in soil gas samples
from 20 to 95 feet below surface. Results of
vadose zone modeling indicate that vapor
migration in soil gas will not result in
detectable concentrations (with currendy
D-2S
-------
available methods) of VOCs in grouadwatet
within a minimum of 30 years. if current
conditions are maint2ined. In that time
interval concentrations in soU gas will diffuse
to the soU surface and be emitted to the
atmOSph.e.
,
A 3O-year interval of VOC migration
was modeled because the maximum exposure
duratioDS for human health risk assessment
(hypothetical resideatial, current worker, and
visitor scenarios) are 2S 10 30 years. n.e
migration of VOCS into exposure pathways
during that interVal may have contributed to
total health'risks. Predictions of future
migration of VOCS become increasingly less
. accurate over time intervals I~nger than 30
'. years. Additional evalution of VOC
migration in soU gas is planned. Remedial
actions for VOCS may be considered in the
OU B ROD if evaluations indicate
- .
groundwater wUl be impacted in the future.
The COCs in surface and subsurface
soils may dissolve. up to their aqueous
solubility limit. or be suspended as colloids in
rain water passing downward through the
soUs. On the basis of vadose zone modeling,
dissolved VOCs and ArochIor 1260 will not
reach the groundwater pathway in detectable
concentrations within a minimum of 30 years;
some COCS from OU Bl may never be
detected in grouDdwater. 1he COCS that may
. ~ carried as colloidal particles are also
unlikely to have any impact on the ground-
. water pathway beneath OU Bl, if current
conditions are maintained.
The enhancement of migration by.
cosolvency requires concentrations of 1" or
more of suitable solvent. The greatest solvent
concentration in soUs in the area of high
Arochlor 1260 concentration was 69 mglkg of
1,2.4-trichlorobenzene. This concentration is
FlNA1JlODI083193/ta1a
one thousand times less than the concentration
needed to increase transport of Arochlor 1260.
Therefore, this mechanism has DO importance
in the subsurface migration of COCS to
groundwater beneath OU Bl.
Potential for Groundwater Transport
GroW!dwater beneath au Bl is con-
taminm"'(f by VOCs. However, the available
data indicate that the cont:aminJnts have
migrated beneath the site from another location
to the north. Results of subsurface modeling.
of organic compound migration and
calculations .of inorganic species migration
suggest that COJlt2min:ants discharged in OU B 1
will DOt reach groundwater in detectable
concentrations for 30 years or more under
current site conditions. Therefore, on the
basis of the available data, the groundwater
pathway will DOt be complete for a minimum
of 30 years beneath OU B1.
4.3.5 Potential Exposure Points
Surface and subsurface soUs containing
COCs to depths of six feet BGS are considered
potential exposure points for workers or future
on-site residents. (Future on-site residential
use has been evaluated in the risk assessment
as a hypothetical case.)
U-26
-------
5.0
SUMMARY OF SITE RISKS
A discussion of potential adverse
impacts on humaD health aDd ecoloJica1
resources resulting from the OU 81 COCS
follows. See Section 4.0 for a list of COCS
for OU 81.
5.1
DUft\8.~ Bt:alth Risks
A Health IUsk Assessment (BRA) was
coDducted to evaluate the poteDtia1 preseIIt aDd
future humaD health risks associated with
exposure to, the COCS in OU B 1 soils. Results
of the risk assessment serve as the rationale for
the cleanup of OU B 1.
,
The COCS used in the BRA include all
chemicals detected during the RI, with the
exception of chemicals whose infrequency of
detection (10 less than 5~ of the analyses),
low concentrations, or low toxicities would DOt
result in adverse health effects.
5.1.1 Exposure ~t
The exposure assessment identified
potential exposure pathways and segments of
the population that may be exposed to site-
related COCS via those pathways.
Poteatial Human Receptors - For
the last 35 years OU Bl has been used for
military purposes aDd is expected to be used
for military, industrial, or commercial
. purposes in the future. Access is controlled
aDd McClellan AFB is surrounded by a high
security fence. Future exposures to COCs at
OU Blare expected to be consistent with .
those arising from a limited access industrial
setting.
Exposures to COCS froin OU Bl were
evaluated for the current DRMO workers on
FINALaODI'072I93Ib&a
D-27
OU 81, the nearby curralt residents, IDd
visitOrs at the site (the general public atteDds
occasional auctions at the DRMO). Lifetime
carcinogenic risks were evaluated for all
receptors. Noncarcinogenic risks were
evaluated for children in the current resideatial
scenario aDd adults in the DRMO worker and
visitor sc:eDario. (Children are DOt allowed at
DRM9 auctions.) Site-specific information
was used in evaluating current risks whenever
possible. .
The risk analysis also analyzed the
risks which would exist if the site were
developed residentially without any
remediation. For this hypothetical SceDario,
where residential development and consequent
exposures would occur at OU B 1, lifetime
carcinogenic risks aDd children's.
DOncarciDogenic risks were evaluated. h was
assumed that the residence was constructed on
a one-eighth acre lot in the area of highest
PCB coQt2minuion.
5.1.2 Poteatial Exposure Pathways
Soil, surface water and sediments,
groundwater, air, and homegrown produce can
serve as exposure media for the poteDtia1
receptOr populations.
Soil - All DOD-VOC COCs were
reported in OU 81 soDs. Three direct routes
of exposure to cont2minated soils were
considered: ingestion, dermal contact, and
inhalation of suspended particulates. lDdirect
exposure via homegrown produce was also
evaluated.
Surface Water and Sediments -
PCBs, dioxinlfuraDs, and inorganics were
reported in surface water and sediment samples
on the site. Exposure to contaminated surface
-------
waters aDd sediments were evaluated for the
hypothetical on-site residents.
Groundwater - As described in
Section 4.3.4, vadose zone modeling results
iDdicated that the OU Bl COCs are unlikely to
reach groundwater in the next 30 years (see
basis for selection of time Wterviil on Page n-
.26) iIi detectable concentrations. Therefore,
exposures to COQt2min2ted groundwater were
DOt evaluated.
Air - Exposures to volatile aDd
semivolatil~ COCs in soil gas can occur when
cont~milUllnts are emitted into ambient air.
lDhalation exposures were evaluated for all
potential receptors.
,
Homegrown Produce - COCS in soil
can be taken up by plant roots. Exposures
resulting from-homegrown produce
consumption were evaluated for current off-
base residents and the hypothetical on-site
residents.
5.1.3 Exposure Assessment
Receptor populations, current and
potential future site activities, and exposure
pathways were integrated into exposure
scenarios representing reasonable maximUm
exposure (RME) and average exposure
conditions, enabling the evaluation of human
health risks.
Four exposure scenarios were
evaluated in the intake assessment. The
Current Worker Scenario evaluated exposures
to the workers in the DRMO yard. The
Current Residential Scenario addressed
potential exposures to the nearest current
residents. The Current Visitor Scenario
assessed exposure to on-site visitors. The
FJNA1JlODI083193/b1a
Hypothetical Residential Scenario assessed
hypothetical exposures to on-site residents.
Residual DRMO worker exposures
after installation of a cap were evaluated in the
Partial Cap and Full Cap Scenarios. The
Partial Cap Scenario assumed that all areas
with PCB concentrations in soil greater than
10 parts mglkg were capped. The Full Cap
Scenario assumed that all nonpaved areas in
the DRMO yard were paved. With the
exception of the reduced exposures caused by
the cap, this scenario used the same exposure
assumptions as the Current Worker Scenario.
The results of these scenarios are presented in
the FS.
Emissions of volatile and semivolatile
COCS were obtained from the vadose zone
modeling. Forklift-generated particulate
emissions were calculated using a U.S. EPA
traffic-generatecl dust model. On-site ambient
air concentrations of COCS were calculated
using a wind-direction sensitive version of the
.box model.. Off-site COC concentrations in
ambient air were evaluated using U.S. EPA's
.SCREEN. dispersion model.
In the DRMO worker scenarios,
parameter values for skin surface area,
exposure duration, and exposure location were
based on information obtained from an
interview with the DRMO yard supervisor.
Table 5-1 presents the parameter
values used to calculate intakes for Current
and hypothetical residential scenarios. Table
5-2 presents parameter values used to calculate
intakes for current worker and visitor
scenarios.
Tables 5-3 and 54 show the cancer
slope factors and reference doses for each of
the COCS.
B-28
-------
TABLE 5-1. VALUES USED FOR INTAKE PARAMETERS FOR CURRENT
AND BYPOTBETICAL RESIDENTIAL SCENARIOS
Value.
Parameter Adult Child
Body weipt 70~ 16~
Inh.lstioa nae 20 ~/." 15 m'/da"
Soil iqa;tioD 100 mg/u.;a 2QO ma/da"
SoilloldiDa em skiD 0.2 mg/~-day (1.01 0.2 mg/cm2-day (1.0)C
Expo&ed skiD surface area 5.000 ~ (5,800r 3,910 cmz. b
&po6ure ~oa 9 yrs (3O)b 6yrsb
Homegrown produce ingestion nae . 0.041 tg/meaJd 0.0094 leg/meal
Meals pet year 1,095'» 1.095b
Exposure frequeocy(Uldi'D"ftt 8Dd surface NA 1.25 dayslyre
water)
Exposure frequeDcy (ambient air) 24 hrsIday 24 hrsIday
, Averaging time (carcinogens) 25,sSO day~ 25,550 day~
Averaging time (ooac:arcinogens) -_.- NA 2,190 days-
Exposure frequency (soil ingestiem. soil dermal 350 dayslyr (36S)b 350 days/yr (36S)b
absorptiOD, inhalation)
. Average case values; values in parentheses were used in the RME case malysis.
b"
U.S. EPA, 1989b. .
C U.S. EPA, 1992a.
d U.S. EPA 1991b.
C ProfessiODal ~IIUIU!.
NA = Not applicable
F1NAlJlODI071I931t8&a
U-29
-------
TABLE 5-2. VALVES USED fOR INTAKE PARAMETERS FOR NON-RESIDENTIAL SCENARIOS
',,1uo1.tjoa Rate
CIIn'eIIt Worker
Partial Cap aad FuD Cap Sceaarios-
70 ti'
10 m!/8 br WOItday ('1J)"
SO mgll br WOItdar (100)11
0.2 mg/err-day:. (1.0)C .
1,765 crrC (3,120;
9 years (2S'j1
8 hours/day,S days/
week, 50 weekslyear
Vuitor Sceaarlo-
70 ti'
20 fliJ/dayb
100 m,/dayb
1.0 mg/err.r
3,120 err II
Parameter
"Body Weipt
Soil ~ Rate
Soil , nAdiqg OD Skin
Exposed SkiD Surface Area
E~~
Exposure FrequeDCY
. 30 yean/'
8 hoursIday, 26 days/year
,
. Values in pareatbeses were used in the RME C¥e aalysis.
Sceaario.
II U.S. EPA, 1989b
C U.S. EPA, 1992&
d U.S. EPA. 1991b
C Va Dyke, 1993
Only RME case was evaluated for the Visitor
FlNAUt0DlO72893/b1a
D-30
-------
TABLE 5-3. CANCER rOlI!OftCY FAcrORS
InluliAtinn Slope Factor Oral Slope -Factor
<,----I (mg/kg/day)" - (1118/ka-day)-.
- PCBs 1.1 1.1
TCDDeq 1.5 ]t 10' 1.5 ]t 10'
At8eaic 1.5]t 101 1.1
CaromiW1 VI 5.1 ]t 102 4.2]t url
Cadmium 1.5]t 101 0.0
1. I-DeE 1.15]t U)"I 6.0]t url
PCE 5.1 ]t ur2 5.1 J: ur2
TCE 1.0 x ur2 1.5 J: 1Cr2
1.1-DeE c: 1.1-Dicb1~
q c: Kilograms
JUg =Milligrams
PCBs c: Polychlorinated bipbeayls
PCE c: Tetrachloroetbeae
TCDDeq = Tetrach10r0dibeqt<)dioxin toxic equivaleats
TCE c: -Trich1oroetbeae
,
FlNAUtODI072893/bsa
n~31
-------
TABLE $-t. REFERENCE DOSES
Value
n...kaI (../kg-day)
Aneaic 3x 1~
C8dmium Sxl~
Ouomium m 1 x 100
Ouomium VI S x 10"'
Copper 3.7 x 10"2
x.-P
Merwry 3x 1~
Molybdeaum 4 x 10"'
Seleaium S x 10"'
Silver 5 x 10"'
ZiDc 3 x ur1
PCE 1 x 10"2
, 9 X 10"'
t,t-DCE
. Evaluated by using California EPA', blood-lead spreadsheet (LEADSPREAD).
t,I-DCE =: I,I-Dichloroetheae
kg ... Kilograms
JUg =Milligrams
PCE ... Tetracblorw.tbeae
FlNAlJt0DJ072893/b1a
U-32
-------
California EPA's blood-lead model
was used to evaluate poteDtiaI adverse effects
resulting from exposures to lead from the site.
This model calculates a blood lead
concentration based on concentrations in soU,
drinking water, and other food sources.
5.1.4 Risk Characterization
Risk characterization uses the results
of the intake analysis and toxicity assessment
to calculate cancer risk values and Hazard
Indices (HI) (for noncarcinogens) for each of
the four sceoarios.
Carcinogenic Risks
,
Chemical-specific cancer risks were
calculated by multiplying the average lifetime
intake rate (Section 5.1.3) by the cancer
potency value; These risks were then summed
across chemicals and pathways to calculate the
total cancer risk in each scenario.
Figure 5-1 shows the results of the
carcinogenic risk assessment, including:
.
Total excess cancer risk in each
scenario and case;
.
Cancer risk by COC in each scenario
and case; and
.
. Cancer risk by pathway in each
scenario and case.
The calculated RME case risks are just
above the U.S. EPA acceptable risk level of
1 x 10--- (40 CFR 300.430) in the Current.
Worker and Current Off-Site Residential
Scenarios. Risks in these scenarios' average
cases and in the Visitor Scenario are less than
this level. The Current Off-Site Residential
r:1NAlJtODI072I931ta18
Sceuario evaluated risks at the nearest resi-
dential area using screening-level models to
calculate conceotrltions in ambient air and
soU. If more sophistic3ted models bad been
used, the calculated risks would probably be
below the acceptable level in the RME case.
Risks in more distant current residential areas
would be less than the acceptable level.
Risk to bypothwC":& on-site residents
living in the worst-case location exceed the
acceptable level. It is highly unlikely that
anyone will experience this risk because reme-
diation would be conducted prior to residential
construction. Hypothetical residents in other
areas of the site would experience risks as
much as several orders of magnitude lower
and possibly below the acceptable level.
Although the calculated cancer risks in
the Hypothetical On-Site Scenario exceeded
1.0 (23 and 1.3 in the RME and average
cases, respectively), they were reponed as 1.0
because a probabUity cannot realistically
exceed 1.0. Tbe calculated risks are the result
of the conservative nature of the calculatioDS.
Noncarcinogenic Health Effects
The potential for adverse chronic DOn-
carcinogenic effects were characterized by com-
paring the calculated intake rates (doses) to an
intake rate that is considered to be the
threshold for significant adverse effects in
sensitive individuals (reference dose). The
Hazard Quotient (HQ) is the ratio of the calcu-
lated dose to the reference dose. If a com-
pound's HQ exceeds 1.0, there is the potential
for an adverse health effect to occur. As a
screening procedure (assuming that all COCS
produce the same noncarcinogenic effects),
HQs were summed to obtain the HI. The HI
for all cases in all four scenarios are presented
in Table 5-5.
D-33
-------
~
~
~ .
iii
0..
~
oX
CD
c:
1ii
o.
~
'0
- c:
.2
(j
CD
u:
1X10"
oX S 1x10-2
CD S
- '"
O:u
~ E 1x10~
i~
0°
g 1x10~
1X10~
1x10.
o
-r
ca
c:
4Z)
u
en
8
o
:>.
~~
oX
CD
c:
1ii
o
~
RME
.
RME = Reasonable Maxirrom Exposure Case
Average = Average Exposure Case
.
a = See text for explanation
RME Average
RME Average
RME Average
RME
"0
c::
.2
(j
CD
u:
Average
Hypothetical
On-5ite
Residential
Current
Off-5ite
Residential
Cunent
Worker
V'lSitor
RME
Average
. Figure 5-1. Cancer Risk Assessment Summary
FIN.ALR0D1071693/bta
n-34
. PCBs
II TCDDeq
O Others (Prinariy
Arsenic and
CadmiJrn)
mlDermalContict
II Soi If98$tion
. HOIIMrGrown
Produce Ingestion
~ Inhalation
Dermal conlaCt wit! SIdiment,
sediment ingestion. dermal
contaCt wit! surface water
accountIId tor 0% 01 risks.
-------
TA8LE 5-5. IlAZUD INDICES
SeeuriD
Currcai Wcnb:c
Currcai ~~1
. Hypotbctical JiI_itWttUol
VaaifDr .
A.erqe Cue
0.012
0.29
1.4
HE
&ME Cue
0.049
0.61
1.7
0.0018
NE ... Not cva1uat.ed.
If the HI is less than 1.0. chronic
noncarcinogenic effects are DOt likely to occur.
If the HI exceeded 1.0. a more refined analysis
was performed to d~e if noncarcinogenic
effects are likely.
J
The results indicate that the HI is
greater than 1.0 only in the Hypothetical On-
Site Residential Scenario. No chemical-
specific HQs exceeded 1.0 in this scenario.
Using the CAPCOA (1992) procedure to
evaluate organ and systemic Hazard Indices.
no organ or system-specific Hazard Indices
exceeded 1.0 in the RME case of this scenario.
Lead Evaluation
California EPA's (l992b) blood-lead
model. which evaluates lead exposures based
on a calculated blood-lead concentration. was
applied in the Residential and Current Worker
Scenarios. The model was run in tWo modes:
the first only evaluated the lead exposures
from OU B I; the second included the default
background concentrations in air. water. and
. produce that are recommended by the model.
Because only one soil concentration
can be entered into the model. it was
conservatively assumed that produce was
grown in soils with a mixing depth of 1 .
centimeter in the Current Off-Site Residential
Scenario.
F1NA1JlODlO72l93/bsa
D-35
Only adult exposures were evaluated
for the Current Worker Sceuario. It was
assumed that balf of the worker's ingested lead
originates from OU 81. 1be background soil
concentrations for workers was conservatively
assumed to be equal the on-site concentrations.
As shown in Table S-6. child and adult
aposures to ltad auUl OU B 1 generally
resulted in blood-lead levels less than the 10
micrograms per deciliter (,Lg/dL) reference
concentration. Only when using the residential
on-site maximum concentration was the refer-
ence concentration exceeded by the child's
blood-lead level.
TABLE~. BLOOD-LEAD LEVELS RESUL11NG
FROM EXPOSURES.TO OU Bl SOIL
Scmario
BloocIlead ~.
(,cfdL)
Adults CIIiId
0.8 NE
0.1 0.5
1.1 6.9
Cunast Worker
Cunatt Off-Silc Rcaidcatial
Hypothetical On-Silc Rcaidcntial
(average IOU conc:cntra1ion)
Hypothetical On-Silc Residential
(maximum IOU concentration)
2.0
13
NE = Not evaluated.
Rcfcrcocc conccntr81ioal = 10 ".gldL
S.2
Ecological Evaluation
In a preliminary ecological survey
(U.S. EPA. 1993) of McClellan AFB. four
sensitive habitats were identified: Don Julio
Creek and adjacent grasslands with vernal
pools. the Western Collection Ponds. Magpie
Creek. and Robia Creek.
In addition, the burrowing owl. desig-
nated a .species of special concern. by the
California Department of Fish and Game. was
identified at McClellan AFB. The locations of
these significant ecological resources and .
-------
ecoIo&icaJ resources in adjaceat off-base areas
were Qat addnssed. .
No sipificant ecological resources in
OU Bl were specifically identified in the U.S.
EPA report (1993). Most of this highly devel-
oped area is covered with perforated steel
planking, buildings, and asphalt. Vegetation
or wildlife food sources are esE-mially noD-
existent except in the grass areas between the
DRMO and CE yards. The only wildlife that
may be present at the DRMO are spWl
m~mm~ls and birds that are typiCflly found in
non-natural areas. The drainage ditches from
the DRMO yard may occasionally be used by
wildt.ife as . water source but their importance
is minimi7«f by fences restrictinr access and
the ephemeral nature of the drainages. Some
sec:tioDS of these ditches contain small patches
. of grasses and weedy plant species, but are not
. CODSidered to be a useful ecological resource.
Evidence of burrowing owl habitat, however,
, has been observed in some drainage ditcl1
locatioDS.
Potential Exposure Pathways
Magpie Creek is the primary ecological
resource that could be significantly affected by
contaminants at OU B1. The temporary plas-
de liner that was recently installed at the
DRMO should significantly reduce the amount
of PCBs and dioxins that could run off into
these ditches. The more perman~t, low per-
meability cap, described in SectioD 6.0, would
reduce cont2min~nt runoff even funber.
. Burrowing owls could also be affected
- by the OU B 1 contamination if they inhabit the
grassy area between the storage yards, the
grassy fields immediately south of OU Bl, or
the drainage ditches. Although this is DOt the
primary burrowing owl habitat on base, the
recommended burrowing owl ceasus (U.S.
EPA, 1993) would determine if the owls occur
in this area. The potential exposure pathways
would be direct contact with soil, ingestion of
FINALRODlO72l93/b1a
D-36
COnhmin~ food (primarily insects), and
iDba1ation of vapors in burrows aDd ambiem
air. PotemiaI aposures to cont:lmin~on at
PRL-29 would be vinually eliminated if the
c:ont2min~ soils are excavated aDd buried
beneath the low permeability cap.
-------
'.0
DESCRIPI'ION OF ALTERNA-
TIVES
The remedial action goals for tbe
McClellan AFB OU BI site are:
1)
Protect human health and the
en1Jironmem;
2)
Meet ARAb; and
3)
Expedite the cleanup of OU
B1.
The'specific remedial action objectives
derived from these goals are identified in
Table 6-1. The goals aDd specific remedial
action objectives were used to identify and
evaluate alternatives for OU B 1.
,
The Air Force evaluated seven alterna-
tives in selecting tbe final cleanup plan for the
McClellan AFB OU B I site. Figure 6-1
summarizes the seven alternatives that were
developed. The seven alternatives are:
.
Alternative 1 - No Action;
.
Alternative 2 - Capping;
.
Alternative 3 - Excavate, Off-
Site Disposal, aDd Paving;
.
Alternative 4 - Excavate, Off-
Site Incineration, Disposal of
Residuals, and Paving;
.
Alternative 5 - Excavate, On-
Site Treatment, Disposal ()f
Residuals, and Paving;
.
Alternative 6 - Capping and
Treatability Studies with On-
FINAUtODIOI31931b1a
Site Treatment Potential;
. and
.
Alternative 7 - ExcaVate Hot
Spots, Off-Site Disposal and
Capping.
These alternatives were developed
from ~ evaluation that began by setting
cleanup objectives, and included studying the
universe of applicable response actions and
teehnologies that might address tbe OU Bl site
comaminmon. This evaluation and screening
process is documented in detail in tbe FS.
Alternative I is the 8no action8 alter-
native. Alternative 2 includes capping the site
to contain all contaminants. Alternatives 3, 4,
and 5 include removal and disposal or treat-
ment of cont2min2nt$ through off-siie disposal
in a landfill, off-site incineration, and on-site
treatment, respectively. Alternative 6 is a
hybrid of tbe capping and on-site treatment
alternatives, although the treatment aspect
depends upon the results of treatability stu~ies.
Alternative 7 includes excavation of the PCB
hot spots (greater than 500 mglkg) for off-site
disposal and then capping the entire site.
Alternative 3 through 7 also include paving the
site with asphaltic concrete after the primary
remedial actions are taken to contain any
rem2ini"g CODb-mimmts and to keep the
DRMO operational.
The primary COCS for OU B I soils
and sediment are PCBs and dioxins. Secon-
dary COCS include metals in soil and VOCs in
soil gas (see Section 4.0 for list of COCs).
The FS addresses primary COCs, though the
effects of alternatives on secondary COCS,
which may be addressed under other CERCLA
fi-37
-------
TABLE '-L SPECU1C REMEDIAL ACTION OBJECTIVES FOR OU .1
. .
.
.
.
.
,
.
.
PreveDt coataminant exposure to the public 8Dd the eDviIoDmeat throup the procec:ticm of
JI'OUIIodwater. 8Urf8ce W8Ser, air, IDCI diJect CODt8Ct pathways.
Reduce the lite'. c:acer lilt to less tbaD lx10-6, ad reduce the DCJDC8tCiDop:aic Huard IDdG to
_1ha ODe.
.
Meet ARARs.
Rf8"'Ii... IOiIs CCGtaiDiq > 10 IlllIka PCBs &om the surface to 3 feet lOS, > 100 IIIIIkB PCBs
for IOila > 3 feet lOS, ad > 11£,Ik, dioxiDlfutaD (2,3,1,8- TCDD equivaleat).
.
.
Ji~iat... draiDap -'i-a to the exteDt that OM of tile foUowiq is met: coatllmi_t
c:aaceatnUoas in tedilllflGtII are equal to or less tbaD b8cqrouad levels; excess caac:er bealth risk
ii- tb8D lxlO'6; or DCJDC8tCiDop:aic Hazard IDdex is less tbaD 1.
SeI~ alt.ematives that iDclude treJ~. where applicable ad practicable, particularly for
priDcipal threaIs, i.e., for soils containin, > 500 .,1kB PCBs.
CcmtaiD lOils that pose a loD,-cerm threat where tr--~t is not practicable.
Preveat the mipatioa of CODtami...t"'Cf soil particles to OU Bl ditches 8Dd MaaPie Creek.
Easure that cIiscbups from OU Bl ditches cumot cause the receiving water to exceed .y of the
listed CODCeDtratioaa in the CalifonUa IDlaDd Surface Waters Pl8D or McCIe1l8D AFB 8torIIIW8ter
~ permiL
For c:appm, altemativea, cap must:
- Hold up UDder cum:at DRMO opaatioas;,
- Allow wninimal niDwarer iDfiltration;.
- Have a desip life spm of 30 years;
- Allow for potaatial fucure treatmeDt of PCB priDcipal threats;
- PreveDt erosioa of soil beae-~ cap; ad
- Be maintained throughout its desiJD life to ~imilUltl! direct contact IUd iDbalatioa pathways.
.
Optimize costIrist reduction quotieaL
IDclude pota1tial for .dual tnct. remediatioa (i.e., perform expedited remedia1lCtioa BOW 8DcI
coatiDue to evaluate optioaa to further ~iatl! CODtami...t~ eoi1 in future).
.
.
Implemeat iDstitutioaal coatrols to 1) easure lIDd 1IIe will remain iDdustrial; 8Dd 2) miupte short-
tenD i~ 8DdIor 3) supplemeat eqiDeeriDg controls.
.
Coasolicl8te coatAwni...ted soils ad -Wi..,...t from discrete areas (PRL 29, PRL 50, ctraiaage
ditches) at OU Bl to optimize ~.u-tiJtiOG.
Reduce potentiAl for VOC migratioa aDd coastruct weDs to moaitor vOCa in soil ps, 8Dd in the
C?U B ROD, coasi- remedia1lCtioas to reduce the potential for VOC i"rM1l oa JI'OUIIodwater.
.
ARARa - Applicable or Relevant and Appropriate Requiremeats.
DRMO .. Defease Revti1i7.atiOD and Marketing Office.
PCBs .. Polycb1oriDated bipheayls.
2,3,7,8-Tc:I>D.. 2,3,7,8-Tetr.Ic~~~oxiD.
IIIIIkB == Milligrams per kilogram.
I£.lkg ... Micrograms per kilogram.
FJNAUlODI072I93/ta1a
B-38
-------
Alternative 1 - No Action (ScoTe=10, Effectiveness/Cost=O)
.
::I
;: ~
.
-:
: 2
u
1.
~~"
Alternative 2 - Capping (Score=26, EffectivenBss/Cost~9.(J)
5
~
~::::;:::::~;:<[[[}::;:';;;;:;;""
.
.
2
~:s
.!
j2
U
1
o
Alternative 3 - Excavation and Off-Site Disposal (Score=20, EffectivenesslCost=2.8)
5
IfIJP ~.
~ ~
"::::::::~;~:~~~:~~:::~:;;:~}:~::;;::}~~~::::::::::.::~:::::~:~::::)::::/}i~~~~r~::::~::-:"
,. ."
~ 31
:!2
u
1
,
I
0'
5
Alternative 4 - Excavation, Off-Site Incineration, and Disposal
(Score=25, Effectiveness/Cost=O.66)
"
A%B>.';':'''.'' ~
tifL. ..
""Gi&ttt¥t;:{;::'}{t\t:(;::'~ If
.1
.1:-
.,c
eCl
.E
.I:~
c-
e-
E~
~c
.l:c
15:
~~
ie
c
at
L-- EffectiY-
~
<
.I:
'1
c
u
c
.I
~
o
(J
8 " --
8! ~c
!c 1i;
1; s:
..E ..-
:! i c;i
ID .sic
E! g-
;e ~;
r a:~
....
: Implementabillty Co8t
!
.I
i
~
E
.!
j
f1)
KEY
CrIIeria values except COlt
Colt crIaria vaJutl
5 = Meets or exceeds deMiIian(...1mI 01 ClletOn
3= Condtionalv - ~1mI d c:rieriDn
o = Does IIJI meel1he definiiorV- d CIIeriDn
5 = cS15ni1icn
3= S151D5mii1J1
1 = .$5 ID 20 miian
-1 = .$20 miian
Scoq = IUIII of 7 cri1eria values
eff8CtiYell8lllCoat = lum of 5 errectiYtIl8ll values/coat in Smillions
-------
5
Alternative 5 - ExclIvation, On-Site Treatment, and Disposal (Score=24, Effectiveness/Cost=1.2)
J 4
I 3
.
! 2
';
u
o
1fW.....:<.>:.. .<~ft::,... ,.:~;~:...
.;;(.f.:;:::::x:- 'It~' .;.;.:::::--:=;.
:flit....,.. ~ . . ....:::~~
'~f@lW~%n~:<:if«t:::::l!:;fi~
Alternative 6 - Capping and Treatability Studies with Potential On-Site Treatment
. .
(Score=26, Effectivene¥/Cost=6.9)
5
4
.
2
~ 3
.
~ 2
U ,
o'
1
1fW.~' .. ..
"z,:;:,;-.. -.x: :';'.' ".':: '$1:..' ,'.. .0:'.
l~f:f.~-:~:~:;" ' - ~ »::. . '. '.~.;; , . '. ': M"
Alternative 7 . Excavation and Disposal of Principal Threat and Capping the Site
(Score=22, Effectiveness/Cost=4.2)
5
4
.
~
~ 3
.
~ 2
U 1
o
..:-e
il
":15
c-
!I-
c~
==
~I
15:::
..~
- ~i
Ii!
'0
It
:: = i-i
!- .siE
121 ~'ii
u~ :51:
!!. c't:l
.. ..Qi
~l! i,,;
.! . 111
~ a::'8.
c E
...J
i ImpIe_lltabillty Cost
0:
J
i
,
E
!
i
65
.
i
i
..:
-
.
WI
U
C
~
t
c
(J
1--- Effediveneu
-'--
1fW.-.
--liJr-
KEY
CIIIetiI valun ac:ept coat
Cost crbril Y8!un
5 = MetIs or ateeds defllliorVnI8nI of crIerion
3" ConIStionIIy meeu definil~ent aI ClieriDn
0= Does IICIIIl88lIhe de~ aI ClieriDn
5=cSl.511i11icr1
3 = S 1.511:1511i1ia1
1 " »1511:120 IIiIion
.1 . »S20 niIJi(rI
Score = - of 7 crit8ri8 va-
ElflClivennslCost = .II1II of 5 elfediwnns VlIuesIcosIIn SIIIUonI
:l:
Figure 6-1. (Continued)
FlNAUtoDlO72l93Ib18
n-iO
-------
actions, were considered. The primary. media
of concem are soils and drainage ditch sedi-
ments. The exposure pathways that pose the
greatest contribution to total risk are soD
ingestion and dermal contact with contami-
nated soDs.
'.1
Interim Cletmup ~Is for OU Bl
The principal cleanup goals for OU B 1
are the reduction of OU Bl's excess cancer
risk to less than 1(t6, reduction of the noncar-
cinogenic hazard index (HI) to less than one,
and meeting ARARs and/or TBCs.
The key Applicable or Relevant and
Appropriate Requirements (ARARs) and To Be
Considered (TBCs) requirements considered in
this action are as follows:
,
.
Toxies Substances Control Act
(TSCA);
.
Resource Conservation and
Recovery Act (RCRA);
.
OSWER Directive No. 93SS.4-01
(the .U.S. EPA PCB Cleanup
Guidance. [U.S. EPA, 1990]);
.
California Code of Regulations,
Title 23, Division 3, Chapter IS;
and
.
California Inlands Surface Water
Plan.
All of the above are ARARs except the
OSWER Directive, which is a mc.
Interim cleanup goals or the logic for
determining the cleanup standards are pre-
sented in this section by medium and
cont~min2nt type. A summary of interim
FINAUtODI'OI3193/ka1a
cleanup standards summarized for soD, surface
water. and sediment in Table 6-2.
'.1.1 Soilud Stream Sediment
PCBs - Cleanup standards have been
set at 10 mglkg for soils from 0 to 3 feet BGS
and 100 mglkg for soDs and sediment greater
than 3 feet BGS. This is consistent with soil
cleanup standards for PCB spills at industrial
facilities as described in the Gui4tznce on
Remedial Actions for Superfund Sites With
PCB Co1lltlmi1uUion (Oswer Directive No.
93SS.4-01, August 1990).
An interim cleanup standard for PCB in
drainage sediments has DOt been determined;
however, it will be based on a PCB
concentration that either: is equal to a
background concentration in sediments; results
in 1(t6 or less excess carcinogenic risk to
receptors; results in an HI less than 1.0; or has
DO potential to adversely impact downstream
ecologic receptors.
Dioxins and Furan Compounds -:.
The cleanup standard has been set at 1 #lgltg
of tetracblorodibenzodioxin equivalents
(rCDDeq) using I-TEFs for all soD and sedi-
ment. This cleanup standard is based on the
dioxin cleanup level most frequently accepted
in 1982 to 1991 RODs for U.S. EPA
Superfund industrial sites.
Inorganic Species ~ Cleanup standards
for inorganic species have DOt been established
for OU B1. Figure 6-2 presents the decision
logic that will be used to select cleanup
standards for the inorganic species of concern
at OU Bl. The cleanup standard for individ-
ual inorganic species will be based on the
concentration of the species that either: is
equal to background concentration in surface,
U-41
-------
2
~
I
i
~
w
..
TABLE '-2. INTERIM CLEANUP STANDARDS
Media COC CleaDup Levels Genenl RespoDSe AdIoa '. Coauaeat
Surface Soil PCB, 10 mglka No Action , Cleuup leyel hued OD Ouidaace on Remedial ActioDl for Super-
«()'3) feet BOS) fund Sitel with PCB CODtllltioation8
IllltitutioD81 Control
Dioxin 8Dd ftJl'IDI I p&lka TCDDeq' Cleuup level hued OD approved dioxin c:leu-up leyel. at .imil...
Contaioment "tel.
Iaorpaic. To be determined Exc.y.te 8Dd di8pOl8 Iaorganic cleuup level. will be eatablilbect Ulilll the deci.ion
108ic Ibown on Figure 6-2. The cleuup leyel will be bued OD .
Excayate, treat, 8Dd dilp088 1et6 cancer risk, III m < I, or IUrface eoi.I bacqround
coneentratioDl.
tn..itu treatmeot
SublUrface Soil PCB. 100 m8 kg Same u aboye. Cleuup leyel based on Ouidaace on Remedial ActioDl for Super-
(>3 feet BaS) fund Sitel with PCB cootamiDatioo8
Dioxin ancI ftJl'IDI I P&lkl TCDDeq' Cleuup leyel bued OD approved dioxin cleu-up level. .t .imilar
.ite..
Iaoraanic. To be determined Iaorganic cleuup le..l. will be eltablilbed Uti... the deciliOD
logio abOWD on Figure 6-2. The cleuup level will be bued on .
10-' ClllCer risk, III m < I, or IUblUrflc.lOiI background
cODCeotratiODl.
Stream PCB. To be determined Same u for lOil. PCB cleuup leyel. will be establimed Ulloa the deci.ioo 10110
Sediment mown OD Fiaure 6-2. The cleuup level will be bued on. 10-'
cancer rist, an m < I, or 8edlment IOU backpound
Dioxin 8Dd ftJl'IDI 1,.&1k8 TCDDeq' CODCeotradODl.
Cleuup level baaed on approved dioxin cleu-up level. .t .imil...
1aor8aniC' To be determined lite..
Iaoraanio cleuup level. will be eatablimect u.ioa the deci.ion
IOJio mown on Piau.. 6-2. The cleuup leyel will be bued on .
10-' risk, . m < t, or 8ediment IOU bacqround CODCeotratioDl.
(Condnued)
-------
i
I
~
,
~
\oJ
TABLE 6-1. (Continued)
Media COC Cleanup Leveit General Re1ipome Action Comment
Surface Water PCBs. dioxins and Varies Same 88 for lOiI. , Discharges from OU B I ditches cannot cause receiving WIden
forans:lnorganics to exceed criteria established in the California 1ntaDd. Surf8ce
Water Plan and McClellan AFB Storm Water Discharge
Permit. A monitoring program will be established to confirm
this.
Groundwater PCB.: dioxins and None identified. None. No remediation goal. will be developed for ,roundwater.
forans Soil 188 and groundwater monitoring will be conducted under
a documented program. The need (or remedial actJon for
groundwater impacts from au 8laource. will be considered
In the au 8 RUFS and ROD. Modeling hu Indicated that
PC8s and dioxins will not Impact lroundwater beneath au
81 within 30 yearl.
. Baaed on OSWER Directive No. 9JSS.....o1 (U.S. EPA). 1990.
. Tbe Ipglkg concentration Is the sum of all dioxin and foran ilOmers. reported 81 a 2.3.7.8-TCDD-equivalent coocentratlon.
BOS - Below ground surface
cae - Contaminant of concern
mglkl - Milligram per kilogram
PCB - Polychlorinated biphenyls
TCDOeq - TCDD equivalents
pg!kg - Microgram per kilogram
-------
Identify Inorganics
of Concern
,
Determine Surface Soil
or Sediment
Background
Concentrations
for Inorganics
Calculate Inorganic
Concentrations Equal
to 1 ()'41 Risk &
Hazard Index 01 1
Is Concentration
/'1 ()'41 Risk or Hazard
'" Index 01 1 >
Background?
po
Yes
Use 1 ()'41 Risk or
Hazard Index Based
Concentration as
Cleanup. Level
Use
Background
as Cleanup Level
NOTE: Risk concehVations based on Current Worker Sc:enario
Figure 6-2. Inorganic Cleanup Standard Determination for OU 81 Surface Solis and Sediments
MCOU8625.PM& - VMG 711 5.'83 SAC
FtNAU.ODI071I93Ib1a
D-44
-------
subsurface, or sediments; results in lr or less
excess risk to receptors; results in an HI less
than 1.0; or has DO potential to impact
ecologic receptors.
6.1.2 SurIac:e Water
Spe(:ific cJeanup sW1dards Ire DOt
established for s\lfface water in OU B 1 df~o
age ditches. Any discharges of cont2minM~
surface water from OU B 1 must, however,
comply with the overall guidance in the:
CDlifomia Inlan4lSurflla Water Pltm
(ISWI' [SWRCB 1991J). Discharges
from the OU Bl ditches cannot cause
the receiving waters to exceed any of
the listed concentrations (Tables 6-3A
and B).
,
McOeUan AFB storm waler discharge
permit (NatioMl Pollution Discharge
Elimination System (NPDES] No.
Cf000(359). Discharge from the OU
B 1 ditches must comply with the
NPDES permit and DOt cause
exceedances of water quality objectives.
The soil, sediment, and surface water
cleanup standards were selected based on pro-
tectiveness criteria and the requirements of
law.
6.2
Stream Sediment Remedies
Operable Unit Bl ditches contain
CODt::aminated soil particles that were
transported with surface water runoff from the
DRMO storage yard. Because the origin of
the cont::amin3tion was the DRMO storage.
yard, any contaminated sediments requiring
remediation will be brought baCk to the
DRMO and consolidated with OU Bl soils.
~AaODIOI3I931ta1a
U-4S
The decision logic that will be used to
select the remedy for cont2min:ated stream
sediments is shown in Figure 8-1. Any
conmnin::ated sediment concentrations greater
than the cleanup standards will be dredged and
combined with OU B 1 soils for remediatioD.
6.3
Surface Water Remedies
. Any remedial actions taken at OU Bl
will be designed to prevent 'CODuminated
sediment from being transported via surface
water off OU B 1. Any actions taken in
ditches will be conducted to limit ecologic
impacts in the ditches and downstream.
Surface water concentrations should be
monitored to determine if surface water runoff
from OU B 1 will cause exceedance of the
ISWP and NPDES permit for McClellan AFB.
Surface water, cap integrity, drainage channel
liner, vadose zone, and groundwater
monitoring plans will be developed and
submitted to regulatory agencies for approval.
6.4
Soil Remedies
The seven remedial alternatives selected
for detailed analysis in the FS are described
and evaluated in this section. Contaminated
stream sediments above cleanup standards will
be consolidated with OU B 1 soils prior to
remediation.
The extent"of PCB-cont::aminated sedi-
ment, surface water, and soil are based on RI.
sampling results (see Section 2.0). Table 64
summarizes the area and volume of PCB-
cont2minated soils and sediments in OU Bl.
-------
TABLE 6-3A. .ItECEIVING WATER LIMITATIONS mOM THE INLAND SURFACE
WATERS PLAN: PR0TECI10N OF AQUATIC un:
.t-Da1 Dail1 1..J1our
C-O!8d"-at Uait A.enp Annp A~
Ana1ic I'8IL 190 360
Cadmivm ~rL b b
CItoIIIium (VI)8 I'8IL 11 16
Cappa' I'8IL c c
Le8d I'8IL d d
Merauy I'8IL 2.4
PCB8* DIlL 14
Sel8lium I'8IL 5.0 20
Silver I'8IL
ZiDc I'8IL f f
'~n~
Maxim...
e
,
. See ~ix 1 in the IDJ8Dd Sur&ce Waters PIaD for defiDitiaa of aen..
. DisCbaqes may, at their optioa, med this limitatiaa u total chromium.
.. 4-Day Averqe Cldmium, eO.7IS2H - 3.490; I-Hour Avera. cadmium, e1.l2lR - s.m. For eumple, where
IwdDess ia 5OJDlIL, the 4-Day Avenp cadmium - 0.66 "..IL ad the I-Hour Averap Cldmium ~ 1.8
",.IL.
c 4-Day Average copper - e0.8545R- U65; I-Hour Averap copper ... eO.M%lH-l.46C. For eUmple, where
budDess is SO qlL, the 4-Day Averap copper .. 6.S "..IL ad the I-Hour Avenp copper - ".,IL.
. 4-Day AVeraJe 1- - et.2'73R - ~1M; I-Hour AVer8Je 1- - el.mR - 1.460. For eumple, where bardDess is
50 maIL, the 4-Day Average 1- - 1.3 MIL aDd the I-Hour Average lead - 34 "..IL.
C IDstaDtaDeoUs Maximum silver - el.72H-6.5%. For example, where bardDess is 50 maIL, IDstaDtaDeoUs
Maximum silver - 1.2 "..IL.
r 4-Day Average zinc .. e0.I4'7'JH + 0.7614; I-Hour Average zinc - e0.I4'7'JH + 0.I6CM. For eumple, where
bardne88 ia 50 qlL, the 4-Day Avenp zinc .. S9 "..IL ad the I-Hour Averap zinc - 6S I'8IL.
FlNALRODJ072893/b1a
D-46
-------
TABLE ~3B. RECEIVING WATER LDm'ATlONS mOM THE INLAND SURFACE
WATERS PLAN: PROTECTION OF RUMAN HEALTH
cOmtitueat
N~
Cadmium
OIromium cvn-
Coppec
Lead
Mercury
Selenium,
Silva'
EDcfi.. 01' PotmtiaI
Souras or Drinking Wat8'
Uait 3O-Day AYenge
Uait
Other Waters
3O-Day A ftI'8Ie
Zinc
""lL
qIL
""lL
p.gIL
DIlL
""lL
mglL
mgIL
10
0.05
1,000.0-
so.o
12
10
0.05
5.0--
DIlL
12
CarciDollens-
~
Arseoic
Beazeae
PCBs-
TCDD. equivalents
""lL
""lL
paIL
PIlL
s.o
0.34
70
0.013
""lL
pglL
pglL
21
70
0.014
. Discbargers may, at their option. meet this limitation as total chromium.
. = See Appendix 1 in the Inland Surface Waters Plan for definition of terms.
- = Taste and/or odor-based objectives.
mgIL = Milligram(s) per liter; ",gIL = microgram(s) per liter.
pgIL = Picogram(s) per liter; .-. = not applicable.
FlNAUlODJ072l93/b1a
U-t7
-------
TABLE '-4. AREA AND VOLUME CALCULATIONS FOR JlCB.CONTAMINATED SOIL AT OU 81
Depda 01 Volume PIlls
Anal Eatea& Co.,.....8IL.a Volume 1S~ Swell F8CtGr
Area oIlatenIt ~) (ft) (cubic ,...) (cubic JVds)
PCBs :> SOO m&Ik& 12,000 1 3.111 3.578
PCBa :> 100 m&Ik& 11.100 1.5-7 3.87£ (.a
Pes. I~SOO m&Ik& 124.000 1.5 6.889 1,9'12
DraiDage ditchea r1,05O 1 1.002 1.152
(4.115 feet loag8)
TOTAL Volume: u,65%
. -
. Width vari~ from 4 feet to 1 feeL
mglkg .. Milligrams per kilogram
1
FlNAUtODI072I931ta18
U-41
-------
6.4.1
AlaerD8dye 1 - No Adioa
~~~
. Description - The DO action alterna-
tive represents a baseline against which the
other alternatives can be compared. It relies
on natural physical, chemical, and biological
processes to reduce CODt2min3nt concentrations
over an extended period of time. No contain-
ment, disposal, or treatment process options
are included in this alternative; however, long-
term monitoring is included.
,
Evaluation - Airborne emissions and
the dermal c(tntact pathway are not elimin2ted,
and surface water impacts are still possible
without engineered controls. However, the
existing fencing, PSP, and 4S-mil HDPE liner
will reduce the potential for dermal contact,
fugitive emissions, and surface water runoff
from the areas of highest PCB concentrations.
lbe alternative ~s to comply with
ARARs and also fails to protect human health
and the environment. Toxicity or mobility of
the contaminants is not reduced because no
treatment is performed. Potential shon-term
exposures resulting from disturbances of
cOotaminated soils will not occur. However,
. the alternative offers DO short-term benefit to
human health or the environment. The
alternative will also restrict DRMO operations
because of the existing HDPE liner over the
PCB hot spot and the fence surrounding it.
The long~rm monitoring (30 years)
would cost approximately $23,000 annually
with a present value of approximately
F1NAlJlODlO72l93/tMa
D49
S4OO,OOO ($2Slton). The cost 8tim2te is
assumed to be accurate within -30~ to +50
percem.
,.4.2
A1temative 2 - Capping
.~~--
Description - This alternative
involves the installation of an asphaltic
concrete cap over all soils contaminated above
the cleanup standards. It closes several migra-
tion pathways to reduce risks to human health
and the environment, and allows natural physi-
cal, chemical, and biological processes to
achieve the cleanup standards.
Evaluation - Capping protects
human health and the environment by creating
a barrier that reduces surface water infiltration,
prevents soil ingestion, dermal exposure, aDd
inhalation of contaminated dust. Migration of
contaminants from au B 1 in surface water is
eliminated. Capping is a proven, widely-
applied technology. The alternative addresses
all potential cont.aminants at OU Bl.
To comply with ARARs, the cap must
prevent migration of contaminants to ground-
water (U.S. EPA PCB guidance [U.S. EPA,
1m)). Site-specific modeling indicates that.
PCBs and dioxins will not migrate to ground-
water, even without a cap.
A cap must be maintained and periodi-
cally repaired. Failure of the cap could result
in ingestion or dermal contact of contamin3ted
soil, inhalation of contaminated dust, increased
surface water infiltration, and surface water
-------
transport of COnt2mift!lfed soU particles. With
m~inten~nce. this alternative is effective long
term. The use of the site would have to be
restricted to activities compatible with the
rDateria1s and design of the cap, such IS an
open area. storage, or parking. Monitoring of
the cap, surface water, liner vadose ZOlle, and
aroundwater to assure IOD&~ effectivmess
of the altenWive woukl be ~IIIIP-ftted in an
operations and mainteDal1ce plan prepared
prior to construction of the cap.
~
. No treatment is performed; therefore,
the toxicity; mobilit1, aad wlume of COD- .
t2minated soil are 1IOt reduced.. Because no
excavation would occur, there is little poteDtial
for shon-term exposure to cont~mift~ted dust
and gas-phase cont~min~nts. A cap is very
effective in the shon term, elimift2til\g expo-
sure pathways and protecting human health and
the environment.
This alternative would have a rela-
tively small. shon-term impact on DRMO
operations. When completed, capping would
have no long-term effect on DRMO opera-
tions. The time needed to complete the cap is
estimated to be approximately three months.
A conceptual cap design is shown in
Figure 6-3. OU Bl will be capped in unpaved
areas where PCB, dioxin and furan, and
iDOrgariic concentrations exceed the cleanup
standards; however, partially capping OU Bl
- would impact DRMO operations. A cantin- .
uous asphaltic concrete covering over all .
exposed soil surfaces in OU B 1 would have
the least impact on the operations. Therefore,
if the capping alternative is selected, a cap .
over the entire OU B 1 area would be COD-
suucted. Existing paving overlying soUs
exceeding cleanup levels would be upgraded to
at least the standards of the new cap and would
FlNAUlOOlO72.l93/b1a
be included in the capping monitoring
program.
The estim1:lted cost (within -30S to
+50"> to implemem this alternative is $2.2
million ($127/ton), including the present value
of long-term monitoring.
,.4.3 . Alternative 3 - Excavation and 011'-
Site Disposal
lIP> --..
~::i:~::t~~lW~MHt:::r~~~:@t~::tttd'
Description - For this alternative,
approximately 12,000 cubic yards of soU and
sediments containing contamin~nts greater than
the cleanup standards would be excavated and
loaded into transpon vehicles, weighed to
ensure compliance with Department of Trans-
ponation (DOT) load requirements, properly
manifested, and transponed to a TSCA- .
permitted hazardous waste disposal facility to
be stabilized and stored. Clean soil would be
backfilled to restorcfthe original grade of the
site and all unpaved areas would be paved to
allow DRMO operations to continue.
Evaluation - The alternative could
be implemented quickly using standard COIl-
suuction equipment and techniques. The
excavated materials would be isolated in a
permitted landfill, thereby reducing the
COJJb.minaDt exposure pathways. SoUs COIl-
aminated with both metals aDd semivolatile or
nonvolatile organic compounds may be treated
D-SO
-------
"
I
-I ! - -
I I ;.
I
.j
!
; .
I ~
i
i ;
i i
! :
;
: I
,
. .
:t
~ .
.j .
I: J
......
. . . .
I
. . I. .
. . . . .
. . . . .
. . . .
'8- . - . . . . . . . . . . . . . . . - . -
......................
. :1: : : : I: : : : : : : : : : : : : : : :
. . . . .
............
. . . .
..........
-
.~C".........
..........
.........'.
......
. . . . .
. . . .
.....
. .. . .
.........
.........
.........
. . . . .
. . . .
. . . .
. . . . .
.....
. . . .
. . . . .
........
. . . . .
~
2CO
.
N
LEGEND:
~ PROPOSED ASPHAI.. TIC C~
D EXISTING PAVEMENT
sc..u it< .~
Cap Profile
CONT AMINATED SOIL
i
\
I
I
PERFORATED STEEL I
PLANKING
REMOVE
~ REQUIRED
Figure 6-3. Conceptual Design of the Capping Alternative
FlNAJ-JOOIOTU91",,,.
U-SJ
-------
I\.
in one Step. Additives aDd reagents are widely
available and relatively inexpeDsive.
,
Excavation activities would have signi-
ficant potential to release dust-bome and
airborne coataminJants to be spread by winds
when the soils are disturbed, theceby increas- .
ing the risk of exposure for the construction
worker'S. aDd nearby community. The PSP
mUSt be removed aDd decoDhminJated to imple-
ment tbis alternative; this could also create
shon-term exposure risks to workers. The
alternative flust meet SacramentO Metropolitan
Air Quality Management Disttict (SMAQMD)
air quality requirements and TSCA landfill
: requirements. Soils that have Toxicity
Characteristic Leaching Procedure (TCLP)
concentrations exceeding RCRA Land Disposal
Restrictions (LDRs) would have to be
stabilized at the Class I site prior to
landfilling, thereby significantly increasing
COSIS. This alternative would not be
implemented due to LDRs if both TCLPs are
exceeded and halogenated organic compounds
(H0Cs) (including PCBs) are greater than
1,000 mglkg. Because landfilling does not
reduce the toxicity, mobility, or volume of the
contaminants, the objective for permanent
solutions involving treatment will not be met.
The long-term effectiveness depends on con-
tinued careful operation and mainteDance of
the landfill by its operator. Failure of con-
tainment at the disposal facility could affect
groundwater and surface water quality, result
- in dermal contact, or inhalation of the COD-
umin:.nts at the disposal facility. Currently,
only Keulemen Hills is pecmitted to accept this
waste in California. New regulations may.
eliminJate acceptance of pcB-contaminJated
- soils at this landfill.
ExcaVation. and disposal would have a
shon-term impact on DRMO operations.
FlNALa0DlO72893/b1a
Activities at the DRMO would have to be
temporarily restricted while excavation took
place, baddill was placed aDd compacted~ and
the DRMO yard was pavecl. The work
schedule is estim!lted to be six months.
Concerns ielated to equipment decont2mination
would reduce implemenubility; the removal
and deco~amirnation of the PSP also increases
the difficulty and cost of iQJplementing this
alternative.
The eshll1J:1t"(J cost (within -30" to
+SO~) to implement this altematiVf: is approxi-
mately $5.6 million. ($349/ton).
6.4.4
Alternative 4 - Excavation, Orr-site
Incineration, and Disposal
."."." :..'.;.:.'.',
. ~..
1 ".~Z'@ltltt;:~:rm:fMt@tittEi$' ""
Desaiption - Approximately 12,000
cubic yards of CODt~minJated soil and sediment
would be excavated and transponed to an off-
site facility for organic chemical and stabil-
ization of metals contJamiftJaftt destruction.
Incineration in a TSCA-permitted incinerator
has been selected as representative of the
applicable treatmept process options. Treated
soils will require Stabilization prior to disposal
in a landfill. Clean soil would be brought to
OU Bland backfilled. It would also be paved
to keep DRMO operational.
Evaluation - Implementation of this
alternative would destroy the PCBs. dioxins.
and furans permanently reducing their toxicity,
mobility, and volume. The alternative could
be implemented relatively quietly using
proven excavation and incineration techniques.
D-S2
-------
The iDorpDic residuals wUl coDtaiD CODCeD-
tratiODS of metals 1hat would mate it necessary
to stabilize and then dispose of the residual in
a hazardous waste landfill. No loq-term
operation or lNIinteruance is expected for this
alternative.
The altemative meets ARARs for soil
treJltmlo.nt of PCB and dioxin CODbmift2t\oD;
however, SMAQMD air quality requirements
for excavating the soils must be met. A land-
fill disposal facility for iDcinerJrDr ash would
be selected.in accordance with the RCRAI
TSCA regulatiolll.
,
Excavation activities would bave the
significant potential to release dust-bome and
airborne contaminaftt$ to be spread by winds
when the soils are disturbed, increasing the
risk of expoSure for the coDStrucUon workers
and nearby community. Although incineration
is a proven and reliable method for destroying
organic conuminant5 such as PCBs and
dioxiDS, very few commercial facilities wUl
accept wastes with these contaminants. There
is also uncertainty that an approved facility can
incinerate the dioxin-cont~ini"g soil.
Therefore, the implementability of this
alternative is very low.
This alternative bas approximately the
same impact on the DRMO as the excavation
aDd disposal alternative. The schedule is
estim~ to be 12 months to allow for select-
ing a facility, a possible trial bum, excavation,
and off-site transportation.
The estiD"lated costs (within -30~ to
+SO~) to implement this alternative is .
approximately S3S million ($2,IS6/ton).
FINAUlODI072I931ta11
,.".5
Al&emadve 5 - Euafttioa, Oa-Site
Treatment, Disposal
1fIJ"::{~:$:'" .,::*ft/'. 'Ihb.
..:::.;.:::::::;-:::.:.. 'i~ ..:.....::::'.(:'~.
i\f;::':""Y .1 .:tt:
.!:lfttl::ttlmW\::{;;::i.JiM~
Desaiptioa - This alternative con-
sists of excavation aDd on-site treatment of
approximately 12,000 cubic yards of contami-
nated soil and sediment. For costing purposes,
it was assumed that a temporary incinerator
meeting TSCA requirements would be brought
on site for the duration of treatment.
Coot2min:tred soil would be excavated and
processed through the incinerator; the resulting
treated soil would be stabilized and backfilled
on site. The site would then be paved to keep
DRMO operational. All combustion gases
would be collected and treated to SMAQMD
emission standards. This alternative includes
destruction of CODt2minants to achieve cleanup
standards.
Evaluation - This alternative is
similar to the off-site treatment alternative,
except that all processes are performed OD site
and treated soil is backfilled at the site.
However, any soil which exceeds TCLP limits
for metals must be transported to a Class I site
for stabilization to meet LDRs prior to
landfilling. All of the same negative factors of
alternatives 3 and 4 involving excavation
would be present. The alternative must meet
chemical-specific ARARs and action-specific
ARARs for treatment of soil for PCBs and
dioxiDS. The alternative must also meet
incinerator performance standards. The repre-
sentative technology (mcineration) is available
and implementable. However, because of the
D-53
-------
dioxin contamin:arion, there is significant
uncertainty that ARARs could be met during
either the on-site trial burns or long-term
operation. Treated soils will contain metals
that will require stabilization prior to use of
this material as bactfilI.
This alternative would affect the
DRMO to a greater extent than the excavation
and disposal alternatives because the work
schedule is estimated to be 24 months to
accommodate treatability stUdies, on-site trial
bum, permitting, a relatively slow soil
throughput for treatment, and paving.
The estim:ated cost (within -30% to
+50%) to implement this alternative is $19
million ($I,175/ton).
~
6.4.6
Alternative 6 - Capping and Treat-
, &binty Studies with Potential On-
Site Treatmen~
":~(..'<':': e':::::...'::::,:"
.
Desaiption - This alterDative
involves implementing Alternative 2 along
with a commitment to continue evaluation of
on-site treatment technologies. Risk will be
reduced quickly by installation of a cap
installation to eJimin,tp. surface exposure
routes, and the reduction in toxicity and .
volume will be evaluated through treatability
stUdies. Evaluation of potential treatment'tech-
nologies wlll involve bench-scale and/or pilot-
scale testing with soil from OU B1.
Potential treatment technologies,
bench-scale, and/or pilot-scale treatability
FlNALRODI0831931b&1
studies must meet the following performance
criteria to be evaluated further for OU B 1:
.
The ability to initially achieve
a PCB cleanup leveJ of less
than 500 mglkg with a further
reduction to 10 mg!kg
possible;
.
The treatment technology wlll
be able to destroy contaminapts
leaving less than 10" of the
original contamin:ant mass as a
by-product; and
.
The ability to achieve a
cleanup level of less than 1
pglkg for TCDDeq.
An annual report wlll also be prepared
to document any results of treatability stUdies
performed, new technology review, and
recommendations for future treatability stUdies
or selection of a treatment process for Ou. B 1
soils.
Evaluation - The potential on-site
treatment technologies that bave been identi-
fied for continued evaluation include the
following:
.
High Temperature Thermal Oxida-
tion is the combustion of organic
materials to produce carbon dioxide
and water, which leave the process as
flue gas, and ash residues derived
from the noncombustible material in
the soil matrix.
.
Base Catalyzed Decomposition Pr0-
cess dechlorinates hydrocarbons,
including PCBs and dioxin/luran
compounds. The process replaces the
U-S4
-------
,
chlorine ioDS with hydrogen,
producing biphenyl and sodium chlor-
ide. Key variables in the reaction are
temperature, base catalyst (i.e.,
sodium hydroxide) concentration, and
hydrogen donor concentration.
.
Gas-Pbase Thermo-Chemlcal Reduc-
tion desttoys chlorinated hydrocarboDS
such as PCBs, dioxins, and chlori-
nated pesticides. This process uses a
proprietary soil/co~minant separation
process, followed by reduction of the
seParated CODt2minaQt phase, in a
thermal reactor in the presence of
hydrogen (reducing agent).
.
Solvated Electron Solution Debalo-
IsmtiODSdectivdyco~muhu~
genated organic compounds. such as
PCBs, to metal-huide suts and
organic residuus. CoDnminated soil
is washed first with anhydrous
ammonia to solubilize huogeDated and
noDhuogenated CODt.2minants. Cal-
cium metal is theD used as the solvat-
ing agent to destroy huogenated com-
pounds. NoDhuogenated compounds
are recovered from the ammonia solu-
tion for separate treatment and/or
dispow.
.
Solvent Extraction is a type of soil
washing technology utilizing a solvent
as the contact medium to remove the
coes from the soil and concentrate
them in a liquid phase. Various sol-
vents can be used (e.g., triethylamine
or propane). This process produces a
liquid phase containing the coes that
require further treatment.
fINAUtODIOI31931t818
u-ss
.
Thermal Desorption utilizes a rotary
kiln to thermUly desorb the hydrocar-
bon from the soil matrix. Light and
heavy bydrocarboDS are separated; the
light hydrocarboDS are recycled to the
process as combustion fuel, and the
heavy hydro<:31'bons containing the
COQ; are collected as an oil hy"
product. The oil by-product requires
additional treatment. .
.
In Situ Biodegradation utilizes
indigenous microbes to biodegrade
PCB and dioxins without disturbing
the soil. Anaerobic bacteria would be
used to dechlorinate higher PCB
coDgeners through reductive dechlori-
Dation. Aerobic bacteria would then
degrade the dechlorinated PCB
congeners to carbon dioxide and
water. Nitrogen, air, nutrients, and
water would be introduced to achieve
the desired environment under the
cap.
Alternative 6 has the same benefits as
Alternative 2, but includes the option to imple-
ment treatment and achieve destruction of
principu threat concentratioDS (> SOO mglkg)
in the future. This duU-track, I) capping and
2) treatability studies, approach to remediation
meets the criteria for an interim ROD and
U.S. EPA's Superfund Accderated Cleanup
Model gous of performing expedited action to
elimin:ate immediate hwth threats and
continuing to pursue effective optioDS for final
remediu actiODS.
The effect on DRMO operatioDS under
this utemative are the same as capping, with
the addition of sbort-term access required to
obtain soil for treatability studies. The access
requirement would be rdatively limited and of
-------
shon (Jess than one week) duration. Capping
will require approximately three months to
complete. Treatability studies will require at
least two to three years to complete.
The estimated cost (within -30~ to
+SO~) to implement this alternative is $2.6
million (SI61Iton), which includes S2OO,OOO
for conducting initial treatabUity studies.
6.4.7
Alternative 7 - Excavation of Hot
Spots, OIf-5ite Disposal8Dd
Ca,pping
-..-
j!fJ> .."
~
~
Desaiption - This alternative blends
the benefits of capping and excavation. The
principal threat is removed (approximately
3,600 cubic yards of soil with a PCB
concentration exceeding 100 mglkg, to be
certain to capture all PCBs exceeding 500
mglkg), as is the potential for dermal contact
or inhalation of the re",:aini"g soU. As in
Alternative 3, soU would be excavated and
transported to a TSCA-permitted hazardous
waste disposal facility to be stabUized and
stored. Clean soU would be backfilled to
- restore the original grade of the site and all
unpaved areas would be paved to allow
DRMO operations to continue.
Ev~luation - Excavation would -have
a potential to spread dust-bome and air-bome
contaminants when the soil is disturbed. Since
the excavation would focus on the principal
threat, the potential affects of exposure are
high. The PSP must be removed and decon-
FINAUtOD/083I93/b1a
bmin:lted to implement this alternative, which
also creates a potential exposure concern for
workers. The alternative must meet
SMAQMD air quality requirements and TSCA
disposal requirements. If TCLP analytical
testing indicates that the OU Bl soils are
RCRA characteristic wuws awl if the total
HOC ~ncentrations [mcluding PCBs) exceeds
1,000 mglkg, then incineration would be
required prior to land disposal to meet RCRA
LDRs (i.e., this alternative would DOt be
implementable). Also, meeting SMAQMD
requirements to suppress dust emissions and
DOt create a nuisance could involve substantial
costs and barriers to compliance. Because
landtilling does DOt reduce the toxicity,
- mobility, or volume of the CODt:aminants, the
objective of permanent solutions involving
treatment is DOt met. The long-term effective-
ness depends on the continued careful opera-
tion and maintenance of the disposal site by its
operator. Containment failure at the disposal
facility could affect groundwater and surface
water quality, or result in dermal contact ~r
inhalation of the CODtamin,nts. Currently only
Kett1emen Hills is permitted to accept this
waste in California.
The long-term effectiveness and perma-
nence of this alternative is contingent upon
proper management of the cap. A cap
maintenance program similar to the one
described for the capping alternative would be
developed, documented, and approved.
DRMO would be affected in the shon term by
this alternative, but there would be DO long-
lasting impact. The time required to
implement this alternative is estimated to be 6
months.
The uncertainty of meeting LDRs and
permitting the transportation phase of this
alternative reduces its implementability, as do
D-S6
-------
concerns related to equipment and PSP decon-
t2min2tion. The cost of excavating, trans-
porting, and disposing of 4,400 cubic yards of
soil, and capping the entire site is estimated to
be approximately 53.8 million ($239/ton).
,
FlNALIlODJ083193/b1a
D-S7
-------
7.0
SUMMARY OF 11IE COMPARA-
TIVE ANALYSIS OF ALTERNA-
TIVES .
This analysis compares the key
advantages and disadvantages of the seven
alternatives in relation to the nine criteria set
forth in the NCP. The evaluations of the
altematives are based on continued industrial
use of the site. The following nine sections
correspond to the nine criteria, and each
sectiQn contains'a discussion of alternatives
with res~ to its criterion.
,
A comparative analysis of the alterna-
tives is summarized in Table 7-1 and Figure
6-1. The numerical scores reflect the relative
completeness that a criterion is fulfilled by the
alternative. An effectiveness/cost quotient was
also calculated for each alternative by adding
the scores of the five effectiveness criteria and
dividing by the 3Iternative's cost in millions of
dollars: the greater the quotient, the more
cost-effective the alternative. It is important to
note that each criterion is weighted equally and
that these values should only be used for a
general comparison between the alternatives.
7.1
Protection or Human Health and the
Environment
All alternatives, except the no action
. alternative, are protective of human health and
the environment.
7.2
Compliance with ARARs
All alternatives, except no action,.
have the potential to comply with ARARs. All
alternatives will meet the PCB cleanup goal of
10 mglkg established by the U.S. EPA PCB
Cleanup Guidance. However, off-site alterna-
tives (i.e., disposal and incineration) must be
FlNALRODIOI3I93/tata
performed at a permitted facility meeting
RCRA and TSCA standards. On-site
. treatment must also meet RCRA and TSCA
storage and treatment standards. The
difference in ARAR compliance between off-
site and on-site actions is that off-site actions
must meet both the subsW1ti~/e and permitting
requir~ents of RCRA and nCA, while on-
site actions need only meet the substantive
requirements. Capping alternatives must meet
the requirements of CCR, Titl~ 23, Division 3,
Chapter 15. .
All alternatives requiring excavation
or treatment that would result in air emissions
must meet SMAQMD air quality requirements
for dust and other emissions, as well as the
SMAQMD Rule 453 related to asphalt
emissions. All alternatives can meet surface
water quality ARARs, as long as discharges do
not exceed criteria in the Colifornia Inlands
Surface Water Plan (SWRCB, 1991).
7.3
Long-Term Errectiveness
The treatment alternatives are more
effective long term because the contaminJnts
are destroyed. Capping and disposal are not
as effective long term because the contami-
nants are not destroyed, and management con-
trols must be used to maintain their effective-
ness. All of the alternatives, except no action,
would be effective in limiting exposure to
metals. Implementing the capping alternative
prevents their migration, and implementing the
disposal alternatives removes metals from the
site and contains them in a RCRA permitted
disposal site. Implementing the treatment
alternatives removes the metals from the site
and concentrates them into an ash. The ash
will have to be stabilized and disposed in a
hazardous waste landfill. It is also imponant
to note that this is an interim solution, and
n-S8
-------
--
5!
~
8
r;
I
TABLE 7-1. COMPARATIVE ANALYSIS OF REMEDIAL ALTERNATIVES
=
~
\0
midi,... Criteria
........,- LelIa. T- RedIIdIaII..
elH- midi,.. Toxidty, midi,.
R_ed181 HI8IIIa .. ... c...... .. MohiIity, .. SIIart. T- 18pp.... SI8Ie c..88It1 T"" _'IC-
AIIen8d,. 18""-" "'" ARARI Pera.-. Tre8bII.. midi,.. IJiIItJ c... Au..-' ~.. SeeN Q8odIII8
Aft I No Aclloa 0 0 0 0 0 5 5 10 0
Aft 1 Cappl", 5 5 3 0 5 5 3 26 9.0
Aft 3 Ellcava" 8l1li 5 5 3 0 3 3 20 1.8
Off-Si.. Dilpolll
Aft 4 Excava.., 5 5 5 5 3 3 .1 15 0.66
M-S11e incIDent-
lion, lad DiIpOlll
Aft 5 Exclva", 5 5 5 5 3 0 .1 12 1.1
On-Si.. Treatmelll,
Ind Dilpo..1
Aft 6 Cappl", lad 5 5 3 0 5 5 3 16 6.9
Trea..bllity Studie.
with On-Si.. Treat.
meat PuIe..1
Aft 7 Excavate Hoe 5 5 3 0 3 3 3 21 4.1
SpoCI, Off-Si..
DiIpO..1 lad
Clppl",
. 11Ie88 two cri..ria will be evaluated when the final RVFS Report I. prepared.
. 1111. ntlo provide. 1ft ladleilion or the benefit provided in relation to the coli or each Ilteraatlve. The effective.... I. the "tD or the five effectlvene.. leore.. The
COlt denominator I.che eilimated coli of each al..matlve, In $ mllliOlll.
ARARa - Applicable or relevllII lad appropriate requlremeatl.
Kif
Criteril EllceD! COli .
5 - Mee.. or ellceed. definitlonllnlelll or cri..rion
3 - Conditionally mee.. definltlonllatelll or criterion
o - Doe. not meet the definitlon/iatelll or criterion
COlt Alllec,.
5 - < $ 1.5 million
3 - $1.5 '0 5 million
I - $S '0 10 million
. -1- > $20 million
-------
...
..
therefore, short-term effectiveness is
emphasized over long-term effectiveness.
7.4
Reduction or Toxidty, MobiUty, and
Volume
Only the treatment zltematives reduce
the toxicity, mobility, and volume of contami-
nants. Though the inherent mobility of COCS
is not affected by a cap, capping does reduce
the potential mipon of COCS.
7.5
Short-Term mectiveness
The no action alternative does not
create short-term exposure threats; however, it
offers no short-term benefit to human health or
the environment. Alternatives 2 and 6 are
, very effective _at protecting human health in the
short-term. Alternatives 3, 4, S, and 7, which
require excavation of cont2minated soils,
creates short-term exposure to excavation
workers (through potential inhalation,
ingestion, and dermal contact); this risk is
greatest for Alternatives 3, 4, and 5 because
the exposure tilDe is greater. These alter-
natives do pose some risk to communities near
McClellan AFB during excavation and trans-
port. Dust control measures coupled with
proper health and safety procedures can
mitigate the risks posed during excavation
work.
07.6
ImplementabiUty
The alternatives are technically
feasible and are relatively quickly
implementable. Alternatives 2 and 6 are the
easiest to implement and have the least impact
on the DRMO operations. Alternatives 3, 4,
S, and 7 are more difficult to implement
because of possible LDRs and the lack of
treatment and/or disposal sites accepting
FlNALRODI083I93/b1a
n~
dioxin-contaminated wastes. Thoere are signifi-
cant uncertainties because it may not be
possible to obtain approvals to transport or
treat dioxin-containing soils. Alternatives 3,
4, S, and 7 will also cause the DRMO
operations to be restricted for a longer period
of time during excavation, treatment (on-site),
and backfilling of OU Bl soils, and paving.
7.7
Casts
The no action, capping, and capping
with potential for future tteatment alternatives
have the lowest overall costs. The tteatment
alternatives have the highest costs. The
approximate present worth costs for each
alternative is listed below:
.
Alternative 1 - $400 thousand
(S2S/ton);
.
Alternative 2 - $2.2 million
($ 1271ton);
.
Alternative 3 - $5.6 million
($349/ton);
.
Alternative 4 - $35 million
(S2,IS6/ton);
.
Alternative S - $19 million
($ 1 ,17S/ton);
.
Alternative 6 - $2.6 million
($161/ton); and
.
Alternative 7 - $3.8 million
(S239/ton).
Sensitivity Analysis
A cost sensitivity analysis was per-
formed for the remedial alternatives to evaluate
-------
how slight changes in some of the key
variables would affect the COSt esfim:ates. To
determine the cost sensitivity of the desip
assumptions, the soil volume, present worth
interest rate, and the percentage of capital
costs (used to estimate long term operations
and maintenance (O&M] expenses) were
varied and the resulting effect on cost was
calculated. The analysis results are shown on
Table 7-2.
. No action, capping, and capping with
ueatability studies are not highly sensitive to
unknowns. There is DO volume sensitivity,
and capping is only slightly sensitive to
interest rates. The alternatives involving soil
excavation are very sensitive to the volume of
soil. The cost/volume relationship is
~ essentially 1:1; a 2S~ increase in volume
increases the cost 2S percent. The alternatives
involving excavation are not sensitive to long-
term management factors such as interest rates
and O&M.
7.8
State Agency Acceptance
Both the RWQCB and the DTSC of
the CalIEPA, as well as the U.S. EPA, have
commented on the au Bl Proposed Plan,
RllFS and ROD and have stated that they are
in general concurrence with them. The agency
comments on these documents, as well as the
response to these comments, are presented in
Attachment D.
7.9
Community Acceptance
As discussed in Pan n of this ROD in
Section 3.0, Highlights of Community
Panicipation, the Proposed Plan public hearing
was held on 30 June 1993. Ten comments
were made at the hearing.
FINAUODI083193/b1a
One additional written comment was
received. All of these comments are .
responded to in the Responsiveness Summary
(Attachment A).
Most of the comments at the meeting
related to concerns with potential cootJminant
releases associated with placement of the cap. .
PoteDtial for air emissions, surface water
drainage problems, cap cracking, weather-
related problems, ditch excavation problems,
and cap integrity concerns were all expressed. .
Adequate design aDd construction of the cap,
as well as a comprehensive cap monitoring
program will diminish the potential for
cont2min2nt releases that were the concerns of
the public.
Responses given to public comments
reduced public concerns regarding the selected
remedy. Therefore, there is public
concurrence with the select remedy.
7.10
Comparative Evaluation Conclusions
Based on the comparative analysis, the
Air Force selects Alternative 6 as the alter-
native that represents the best balance of the
nine criteria.
.
Alternative 1 is unacceptable
because public health and the
environment are not protected.
.
Alternative 2 is not effective in
reducing the volume and
toxicity of the CODt2minated
soils.
.
Alternatives 4 and S are very
effective, but have very low
effectiveness/cost quotients due
n~l
-------
i TABLE 7-2. COST SENSITIVITY ANALYSIS
I
".
- AlternaU.e Volmne Doubled I Doubled SeNitl.it,
\S
I Incre8se 25er, Interest Rate OIcM Peruntqe Assfssment
Alt I - No Action No cost impact No cost implCt No cost impact Not Sensitive.
AU 2 - Capping No cost impact 12~ decrease in cost 28 ~ increase in cost Sensitive to flCtollaffecting
long-term management. Not
volume sensitive.
Alt 3 - EXCAvate and off-site t 4 ~ cost increase No cost impact No cost impact Sensitive to volume. Not
disposal sensitive the issues affecting
long-term management.
AU 4 - EXCAvate, off-site 24 ~ cost increase No cost impact No cost impact Very sensitive to volume.
incineration, and disposal. Not sensitive the issues
= affecting long-term manage-
~
N ment.
AU S - EXCAvate, on-lite 17 ~ cost increase No cost impact No cost impact SensUive to volume. Not
treatment, disposal sen~i'ive the issues affecting
long-term management.
AU 6 - Capping and treatability No cost impact IO~ decrease in cost 22 ~ increase in cost Sensitive to facton affecting
studies unless treatment long-term managcment. Not
implemented volulIMI rensitive.
Alt 7 - Excavation of principal 9 ~ cost increase 7 ~ decrease in cost IS~ increase in cost Limited ...olulIMI sensitivity,
threat and capping sensitiVti to fICtOIl affecting
Ioa,-term management.
-------
to extremely high costs ($35
aDd $19 million, respectively).
.
Alternatives 3, 4, S aDd 7 are
less al'ee6ve because of short-
term risks associated with
excavation. transportation.
and/or disposal. There may
also be difficulty in
implementing these alternatives
!*ause of potential LDRs and
meeting ARARs for excava-
tkm. transpo~ aud
treatment of dioxin-containing
soils.
1
Alternatives 3 and 7 are potentially
not implementable due to LDRs if the soils are
considered RCRA characteristic wastes and if
HOCs ex~ 1,000 mg/kg.
Alternative 6 is easily implemented,
reduces health and ecological risks, is cost
effective, and provides the potential for
treatment of cont2minated soils in the future.
FlNALROD/OI31931b18
U-63
-------
8.0
8.1
THE SELECI'ED REMFJ)y
Description of the Remedy
1be selected remedy (Alternative 6),
which addresses the primary risks posed by .
soU COnt2min2tion (cbaracwiud ~ a ptincfpal
threat at this site), com:ists of the following
components:
(1)
J
(2)
(3)
(4)
1be s~ will be capped using a
minimum two-inch thick asphaltic
concrete cover over engineered fill,
eliminming any immediate threat by
minimi~ing infiltration of surface
water and preventing ingestion,
dermal exposure, and inhalation of
CODt2min2ted dust.
-
Sediments in the drainage ditches
leading off the site determined to
contain coDt2minants that pose health
or ecological risks (above cleanup
standards) will be excavated and
placed under the cap. A sediment trap
will be installed in the drainage ditch
leaving the DRMO yard to collect any
sediment transported by storm runoff
that may carry adsorbed cont2min:llnts.
To comply with ARARs, the cap will
reduce contamin;mt releases to air and
groundwater to below measurable
levels.
1be cap will be maintained and
periodically repaired for long-term
effectiveness, in compliance with. a
cap monitoring and maintenance
program. 1bis program will be
developed and approved by the
agencies as an enforceable document.
FDfALRODJ083 J 93/ta1a
U-64
It will be included in the Operations
and Mainten:llnce Plan.
(5)
Surface water, vadose zone soil gas,
and groundwater will be monitored to
assure long-term effectiveness. The
monitoring plan will be documented
. and enforced through the Operations
and Maintenance Plan and will include
sampling and analysis of soil pore
liquid, soU gas. and groundwater.
(6)
Soil treatment technologies will
continue to be evaluated following
specific performance criteria that will
be documented in the RDIRA Work
Plan, providing time to evaluate and
develop cost~ective technologies
applicable as fina1 remedial solutions
for OU B 1. An annual progress
repon will also be prepared.
(1)
Prior to selection of a final remedy.
institutional controls, in the form of
deed restrictions. will be invoked to
ensure that the area of OU B 1 will be
used only for industrial activities.
1be selected alternative is consistent
with the criteria of interim remedial actions
and with the basewide remediation strategy
developed for McClellan AFB. 1be
alternative will protect employees and site
visitors from health risks and prevent further
migration of coDt2mination while a fina1
remedial solution is developed. 1berefore, the
alternative meets the criteria for interim
actions. 1be McClellan AFB remediation
strategy calls for shon-term actions that will
successfully reduce the significant threats to
health and the environment and the continuing
development of cost-effective technologies to
reduce CODtaminaJ'lt toxicity. mobility. and
-------
volume as final remedial SOlutiODS. The total
capital costs of this remedy are estim2tM
(within -30~ to +SO~) at $2.6 million.
The remedy selected will result in
hazardous substances, the COCs. remaining in
OU Bl for an indefinite period of time.
Therefore, a review will be conducted fiw
years after construction of the cap and every
five years thereafter that the hazardous
substances remain. The review will ensure
that the remedy selected continues to provide
adequate prbtection to human health and the
environment.
,
Figure 8-1 presents a decision logic
diagram for remediation of all media in OU
B1. This figure illustrates the decision process
for CODuminants that are present or may be
detected in all-media.
8.2
Statutory Determinations
8.2.1
Protectiveness
The selected remedy is protective of
human health and the eDvironment. Protection
will be achieved at this site in the following
ways:
.
Capping the CODbmin~ted soils
aDd sediments reduces the
chance of either human or
environmental receptors
contact with the contamin:um;
aDd
.
Capping reduces the potential
for conuminants to be carried
in runoff to doWnstream
receptors.
FlNAUtODJ083193/ta1a
D~S
8.2.2 . Applicable or Relevant and
Appropriate Requirements
Chemical-Spedfic ARARs - ARARs
for soil and sediment cleanup Standards have
not been established. However, cleanup
standards of 10 mglkg for soil from 0 to 3 feet
DOS ind 100 mglkg for soil greater than 3
feet BOS for industrial sites "are consistent with
Guidance on Remedial Actions For Superfund
Sites With PCB Contamintltion, OSWER
Directive No. 93SS.4-()1, August 1990, which
is a TBC criterion. Because this cleanup level
is for industrial sites, institutional controls will.
be emplaced to ensure that the use of the site
rem:ain~ industrial. The selected remedy meets
the PCB cleanup standards.
No chemical-specific ARAR for
dioxin and furan compounds was identified.
However, 1 #£Ilkg TCDD equivalent was the
most frequently accepted cleanup level in U.S.
EPA RODs signed from 1982 through 1991.
Because of the previous acceptance of I Ilglkg
TCDD equivalent as a cleanup standard
protective of human health and the
environment, it was considered and accepted
as a cleanup standard for OU Bl soils. The
selected alternative will meet the dioxin
cleanup standard.
7he In/ant! Surface Waters Plan
(SWRCB, 1991) is an ARAR that lists
contaminant concentration criteria protective of
human health and the environment. The
criteria identified for COCS in OU B 1 have
been adopted as cleanup standards. The
selected remedy is expected to meet this
cleanup standard; a monitoring program will
be implemented to assure this.
-------
MEDIA
SED8IEIIrS
-.s
SClLGU
IUllFACEWA1BI
I I
GllCUlJWATER
I I I
--
.. -CIU 81:
--
--
__FS
c--
.10_-
. '- taIDoII.
.-...
.........
-eo.
I
I i
i
~
Kif
1.=
..IS'
S'i~
Cab
cSo
!(Ir
0°
-5"
I !,!o
-;
1:1 . I
t ~
~
~
~
<=::~
~
-------
Action-Specific ARABs - The
capping action must be implemented to meet
the requirements of Title 23, Chapter 15,
CCR. These includ~ the following:
Article I, Section 2511(d) - General
Requirements;
Article 2, Section 2524 - Inert Waste
Classification;
Article 4, Sections 2541 and 2S46-
Construction;
Article 5, Sections 2551, 2556, 25S7,
2558 - Monitoring and Response
Programs; and
Article 8, Sections 2580, 2581 -
ClosUre Requirements.
Potential future treatments of soil may
be subject to certain requirements, such as
permitting, depending on the recommended
treatment system identified from the
treatability studies.
Location-$pecific ARARs - There
have been no location-specific requirements
identified as ARARs for the cleanup of the OU
B 1 site.
8.2.3
Cost En'eCtiveness
The remedy is cost eB:ective because
maximum protection is achieved for the esti-
mated cost of performance. The comparative
analysis of the alternatives (see Section 7.1)
demonstrates that additional remedial action
and the cost associated with that action would
not achieve a measurable reduction in risk, but
that less effort and a lower cost would result in
a measurably higher risk at the site.
FJNAlJlODJOI3t 931t81a
8.2.4
Use of Permanent Solutions, Alter-
native TreatDient, or Resource
Recovery Technologies to the
Maximum Extent Practicable
The selected remedy combines
containment and treatability studies, providing
the best mix of short-term protection of human
health and the environment, and application of
alternative treatmen~ technologies to a long-
term solution. It also allows for the continued
industrial use of the site. While some of the
alternatives not selected provide more imme-
diate permanent solutions (e.g., off-site
incineration), both the risk, costs, and uncer-
tainties of these alternatives exceed that of
capping. The potential for a long-term solu-
tion is also left open by the evaluation of
treatment technologies through treatability
studies.
8.2.5
Preference for Treatment as a
Principal Element
The selected alternative includes an
evaluation of treatment technologies as an
integral part of the cleanup plan for soils and
sediment. The commitment of the signer's of
this agreement to this evaluation demonstrates
their intent to satisfy the statUtory preference
for remedies that employ treatment to reduce
toxicity, mobility, or volume as a principal
element. . .
n~7
-------
9.0
REFERENCES
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Profile for Cadmium. - Prepared for
Agency for Toxic Substances and
Disease Registry. Prepared by
Clement Associates, Inc. Contract
205-88-0608.
-, 1989b. -Toxicological Profile
for Arsenic.8 Prepared for Agency for
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205-88-0608.
--, 1989c. -Toxicological Profile
for Silver. 8 Prepared for Agency for
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---, 1989d. 8Toxicological Profile
for Mercury. 8 Prepared for Agency
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205-88-0608. December.
-, 1990. 8Toxicological Profile
for Selenium. - Prepared for Agency
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Associates, Inc. Contract
205-88-0608.
-, 1991. 8Toxicological Profile
for Lead.8 Prepared for Agency for
Toxic Substances and Disease .
Registry. Prepared by Clement
Associates, Inc. Contract 205-88-
0608. October.
FINAlAODI072I931ta1l
D-68
California Regional Water Quality
Control Board Central Valley Region. .
8Wastewater Discharge Requirements
for McClellan AFB.8 1991.
Friesen, KJ., J. Vit, and D.C.G.
Muir, 1990. -Aqueous Solubilities of
Selected 2,2,7 ,8-Substituted
Polychlorinated Dibenzofurans
(PCDFs). - OIemospheTe 20: 1-2, pp.
27-32.
Hazardous Substances Data Bank,
1992. Prepared by the National
Library of Medical Toxicology Data
NetWork. On line.
Kenega, E.E., and C.A.I. Goring,
1980. -Relationship Between Water
Solubility, Soil-Sorption, Octanol-
Water Partitioning, and
Bioconcentration of Chemicals in
Biota. 8 In Aquatic Toxicology.
ASTM STP 707. Philadelphia, P A:
American Society for Testing and
Materials.
McClellan AFB, 1993. 8Consensus
Statement on Background Inorganic
Constituents in Subsurface Soils at
McClellan AFB. - February.
Palmer, C.D., and P.R. Wittbrodt,
1991. 8Processes Affecting the
Remediation of Chromitpll-
Contaminated Sites.8 .Environmenral
Health PerspectiVes. Vol. 92. pp.2S-
40.
Radian Corporation, 1991.
8Installation Restoration ~gram
McClellan Air Force Base: Operable
-------
Unit B Preliminary Assessment
Summary Report. W Final. Prepared
for McClellan AFB Enviroumental
Management. October.
-, 1993. wOperable Unit Bl
Remedial InvestigationIFeasibility
Study (RIIFS). W Qraft. Prepared for
McClellan AFB Environmental
Management. March.
State Water Resources Control Board,
1991,lnIand Surface Waters Plan.
April 11.
Schwarzenbach, R.P., aDd J. Westall,
1981. wTransport of Nonpolar
Organic compounds from Surface
Water to Groundwater.8 Laboratory
Sorption Studies. Environmenlal
Science and Technology. 15:1~
1367.
u.S. EPA, 1986. Supe1fund Public
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