statistical evaluation of attenuation factors at lowry air force base, co
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Statistical Evaluation of Attenuation Factors at Lowry Air Force Base, CO. Helen E. Dawson, PHD Regional Superfund Hydrogeologist US EPA Region VIII Denver, CO 303-312-7841 [email protected] AEHS VI Workshop October 2004. LAFB TCE Plume. Study Area. LAFB Cross-Section. - PowerPoint PPT PresentationTRANSCRIPT
Statistical Evaluation of Attenuation Factors at Lowry Air Force Base, CO
Helen E. Dawson, PHDRegional Superfund Hydrogeologist
US EPA Region VIIIDenver, CO
AEHS VI Workshop October 2004
LAFB TCE PlumeOff-Site TCE Plume
MW0B21
MW0B04
CP-56
Figure 1
DateTCE
(ug/L)Aug-98 140Apr-00 160 JJun-00 170 JSep-00 150 JNov-00 124Dec-00 75Feb-00 140
N
N”
N
N”
Study Area
LAFB Cross-Section
Depth to groundwater: 6 m
Vadose zone: fining upwards sequence; sand and gravels to sandy
silts.
Saturated zone: sands and gravels
Residential AreaBase
LAFB Soil Gas
Study Area
LAFBIndoor Air & Foundation Vapor
0.01
0.1
110
100
1000
Ne
w P
rov
isio
na
lT
ox
icit
y V
alu
es
Old
Pro
vis
ion
al
To
xic
ity
Va
lue
s
CD
PH
E T
CE
Po
licy
Ca
l EP
A N
SR
L-C
hro
nic
RE
L
De
nv
er
Ho
me
s
AT
SD
R 2
00
2
UA
03
UA
22
UA
04
UA
18
UA
21
UA
23
UA
24
UA
19
TC
E C
on
ce
ntr
ati
on
(u
g/m
3)
TCE ConcentrationsRegulatory Levels Backgroun
dLowry Air Force Residences
Full Basemen
t
½ Basement½ Crawlspace Slab
Sampling Methods Indoor and ambient air:
24-hour Summa; TO15S
Subslab: Summa after 2 L purge; TO15S
Groundwater: Bailer; 8260S
Chemicals 11DCA 1,1-Dichloroethane 12DCA 1,2-Dichloroethane 11DCE 1,1-Dichloroethene C12DCE cis-1,2-Dichloroethene T12DCE trans-1,2-
Dichloroethene PCE Tetrachloroethene 111TCA 1,1,1-Trichloroethane 112TCA 1,1,2-Trichloroethane TCE Trichloroethene VC Vinyl Chloride
Attenuation Factors Calculated
Groundwater to indoor air (GW-IA)
Groundwater to subslab (GW-SS)
Subslab to indoor air (SS-IA)
Data Quality Filters Data excluded if:
GW, SS, or IA value < detection limit IA conc. > subslab conc. IA conc. < OA conc. (IA – OA)/IA < 20%
Chemicals filtered out: 12DCA, T12DCE, 112TCA
Groundwater to Subslab Attenuation Factors
LAFB: UA21
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
SS
Alp
ha
TCE
PCE
c12DCE
11DCA
111TCA
LAFB: UA18
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
SS
Alp
ha
TCE
PCE
c12DCE
11DCA
111TCA
LAFB: UA23
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
SS
Alp
ha
11DCE
TCE
PCE
c12DCE
11DCA
111TCA
LAFB: UA24
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
SS
Alp
ha
11DCE
TCE
PCE
c12DCE
11DCA
111TCA
Groundwater to Subslab Attenuation Factors
Groundwater-to-Subslab Alphas
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
UA03 UA22 UA04 UA18 UA21 UA23 UA24 UA19
Full Basement Half Basement, Half Crawlspace
Slab onGrade
Subslab to Indoor Air Attenuation Factors
LAFB: UA21
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
SS IA
Alp
ha
TCE
PCE
111TCA
LAFB: UA18
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
SS IA
Alp
ha
TCE
PCE
111TCA
LAFB: UA23
1.0E-061.0E-051.0E-041.0E-031.0E-021.0E-011.0E+001.0E+011.0E+02
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
SS IA
Alp
ha
11DCE
TCE
PCE
c12DCE
11DCA
111TCA
LAFB: UA24
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
1.0E+01
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
IA A
lpha
11DCE
TCE
PCE
c12DCE
11DCA
111TCA
Subslab to Indoor Air Attenuation Factors
Subslab-to-Indoor Air Alphas
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
UA03 UA22 UA04 UA18 UA21 UA23 UA24 UA19
Full Basement Half Basement, Half CrawlspaceSlab onGrade
Groundwater to Indoor AirAttenuation Factors
LAFB: UA23
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
IA A
lpha
11DCE
TCE
PCE
c12DCE
11DCA
111TCA
LAFB: UA24
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
IA A
lpha
11DCE
TCE
PCE
c12DCE
11DCA
111TCA
LAFB: UA21
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
IA A
lpha
TCE
PCE
111TCA
LAFB: UA18
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
Mar-00 J un-00 Sep-00 Dec-00 Mar-01
Sample Date
GW
IA A
lpha
TCE
PCE
111TCA
Groundwater to Indoor AirAttenuation Factors
Groundwater-to-Indoor Air Alphas
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
UA03 UA22 UA04 UA18 UA21 UA23 UA24 UA19
Full Basement Half Basement, Half CrawlspaceSlab onGrade
Q4 Generic AlphaQ5 Alpha
Comparison with Figure 3(b)of EPA’s VI Guidance
Figure 3b- DRAFTVapor Attenuation Ratios -
Ground Water to Indoor Air Pathway Basement Foundations
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
0 5 10 15 20 25 30
Depth to Contamination from Foundation (m)
Vapor A
ttenuatio
n F
acto
r
SandLoamy SandSandy LoamLoam