1 Use this area for cover image (Maximum height 6.5cm & width 8cm) Biovapor Model: Use, Application, Comparisons in: Petroleum Vapor Intrusion Workshop Sunday, September 13, 2015 1:00 to 5:00 pm at: 25th National Tanks Conference and Expo Phoenix September 14 – 16, 2015 George DeVaull [email protected]
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Use this area for cover image(Maximum height 6.5cm & width 8cm)
Acknowledgements: Tom McHugh, Paul Newberry, GSI Environmental, Houston.
American Petroleum Institute BioVapor Model
Download at: www.api.org/pviOR Navigate www.api.org to Environment, Health & Safety > Soil & Groundwater Research > Vapor IntrusionFree, asks for registration information (update notification)
Key:• Pick one method; the others are related (and predicted)• Relatively unique to this model (particularly #3)
13
Aerobic Petroleum Biodegradation Rates in SoilAerobic Petroleum Biodegradation Rates in SoilAerobic Petroleum Biodegradation Rates in SoilAerobic Petroleum Biodegradation Rates in Soil
kw = 0.48 /hr (0.08 to 3.0)
Aromatic Hydrocarbons
kw = 40 /hr (7.8 to 205)
Aliphatic Hydrocarbons
• Chemical-Specific Rates
DeVaull, 2011: Biodegradation rates for petroleum hydrocarbons in aerobic soils: A summary of measured data, International Symposium on Bioremediation and Sustainable Environ. Technol., June 2011, Reno.
ww
ieff
Rk
HDL
⋅
⋅=
θ‘reaction length’
Rates for ‘air-connected’ soils
14
Diffusion-Limited Homogeneous Reaction Rates in Soils
Hydrocarbon and oxygen may deplete before permeating through
soil agglomerate. The effect is a reduced observed degradation rate
when diffusion coefficients are lower.
�Quantify: Thiele (1939); Best (1955); Bosma (1997)
Bulk Soil
Oxygen at
Surface
Hydrocarbon
At Depth
Pore Scale
plane of
symmetry
pore
Lp
Concentration
In Soil
soil
particleO2
CxHyO2
CxHy
Concentration in Soil Pores
or microbes, flocs,
biofilm, or soil
agglomerate scale
15
Data: Reduced observed degradation rate
Slower observed water-phase rates at lower air-filled soil porosity
�Predictable by reduced diffusion through soil matrix
BTEX data
median
diffusive column
advective column
soil gas profiles
unsaturated microcosm
kw = kw,0 / ( 1 +Deff / Deff,0 )
0.001
0.01
0.1
1
10
100
1000
0 0.1 0.2 0.3 0.4 0.5
Ae
rob
ic D
eg
rad
ati
on
Ra
te k
w(1
/ho
ur)
Soil Pore Air (cm3/cm
3)
quartiles (range)
Asymptote is high-end
attenuation rate
(aerobic) in groundwater
omit ~
time
16
Reaction Length
For diffusion-dominated transport in (aerobic) vadose zone soils
Distance over which degradation occurs approaches a
lower limit (does not approach zero; not instantaneous)
omit ~
time
�Distance: Diffusion-Reaction Length
� Implication: Modeling could be extended into capillary fringe
� Uses: agricultural fumigant (soil, grain, citrus, tobacco), chemical manufacture, solvent, catalyst, exhaust system scavenger in gasolines containing lead antiknock compounds. Naturally produced by marine algae.
� Aerobic Degradation: aerobic – ubiquitous (HSDB): ‘in one laboratory screening study using
100 soils, half-lives ranging from 1.5 to 18 weeks were determined’
� Uses: production of vinyl chloride monomer, a precursor to PVC. Reported in indoor air from plastic [from China] {Doucette, WJ, et al., 2010: GWM&R 30 (1): 67–73.} Solvent, exhaust system scavenger in gasolines containing lead antiknock compounds. Agricultural fumigant (grain).
� Aerobic Degradation: Davis GB, Patterson BM, Johnston CD. Aerobic bioremediation of 1,2
dichloroethane and vinyl chloride at field scale, J Contam Hydrol. 2009 107(1-2):91-100.
30
Prior Evaluation and Information
Groundwater Evaluation: Risk, Natural Attenuation
• Anaerobic Degradation
• Dehalogenation in the presence of fuel hydrocarbons
31
Risk Evaluation - Narrative
USEPA, 2013: Evaluation Of
Empirical Data To Support Soil
Vapor Intrusion Screening Criteria
For Petroleum Hydrocarbon
Compounds, US Environmental
Protection Agency, Office of
Underground Storage Tanks,
Washington, DC. EPA 510-R-13-
001
�Appendix F. Analysis of Lead
Scavengers: Ethylene Dibromide
and 1,2-Dichloroethane
Presuming No Degradation
32
Vapor Intrusion: Exclusion Distance Evaluation
Supportive, but Sparse Detection Data; mostly non-detect
Example: Peargin and Kolhatkar. 2013
33
Different Approach: Estimate Aerobic Degradation Rates
Example: CA LUFT Site #90099 [data from GeoTracker]� Rejzek, T: Vapor Intrusion of the Lead Scavenger 1,2-Dichloroethane (EDC) at LUFT Sites, presentation at
March 2015 AEHS Conference
� One measured soil gas profile [1,2-DCA] with detections; analysis: same profile, same date, no residual
34
1,2-DCA Aerobic Biodegradation
Data Compilation. Derived water-phase aerobic degradation rates.
kw = 0.087 /hr
1
1
35
EDB Aerobic Biodegradation
Data Compilation. Derived water-phase aerobic degradation rates.
kw = 0.0093 /hr
1
1
36
Data References
Pignatello, JJ, CR Frink, PA Marin, EX Droste, Field-Observed Ethylene Dibromide in an Aquifer After Two Decades, Journal of Contaminant Hydrogeology, 5, 1990, 195-214.
Freitas dos Santos, L. M., A. G. Livingston, Mineralisation of 1,2-dibromoethane and other brominated aliphatics under aerobic conditions, Water Science and Technology, 1997, 36(10), 17-25.
Olaniran, A.O.; A. Balgobind, B. Pillay, Quantitative assessment of the toxic effects of heavy metals on 1,2-dichloroethane biodegradation in co-contaminated soil under aerobic condition, Chemosphere 85 (2011) 839–847.
Herbst, B., U. Wiesmann, Kinetics and Reaction Engineering Aspects of the Biodegradation of Dichloromethane and Dichloroethane, Water Res., 30, 5, 1069-1076, 1996.
Rejzek, T., Vapor Intrusion of the Lead Scavenger 1,2-Dichloroethane (EDC) at LUFT Sites, presentation at the 25nd Annual International Conference on Soil, Water, Energy, and Air, Mission Valley, San Diego, California. March 23 - 26, 2014.
Soil Gas Assessment Report, 101 East Victoria Street, Santa Barbara, California (LUFT Site #90099), GeoTracker [accessed June 2015]. http://geotracker.waterboards.ca.gov/
37
BioVapor - Amend the Chemical Database: EDB, 1,2-DCA
edit the database
addchemical
data
* EDB, 1,2-DCA not included in downloadable BioVapor at API.org
38
Model Comparison: 1-D to 3-D
Example nomagram
�used previously
Soil Gas Screening
3D: Abreu 2009: GWM&R
� & API Publ. 4555
Basement Scenario
Matched Parameters
� Except “Depth”
all aerobic all anaerobic
Application: • Repeat this plot & scenario for EDB & 1,2-DCA•Use BioVapor•This is a sensitivity analysis for depth and source concentration
(att
en
ua
tio
n f
ac
tor)
39
BioVapor Modeling
Benzene
Okay for:
� Total Source Vapor > 10.2E+6 ug/m3; Benzene < 3080 ug/L-water; Separation Distance > 1.22 m (4 ft)
� Target indoor air: 0.31 ug/m3 ; Source Concentration: 7.0E5 ug/m3 in soil gas ; need attn. < 4.4E-7
Acknowledgements: Tom McHugh, Paul Newberry, GSI Environmental, Houston.
American Petroleum Institute BioVapor Model
Download at: www.api.org/pviOR Navigate www.api.org to Environment, Health & Safety > Soil & Groundwater Research > Vapor IntrusionFree, asks for registration information (update notification)