- HyperVentilate Users Manual -

Flowrate Estimation: , OF ;
tion: - Enter your own permeability values (darcy)

Optional
© Medium Sand 3 Ener Reds of Intteace () & Interval Tickness*
@ Fine Sand 4) Optional - Enter your own well vacuum (406" = max)
OSilty Sand
O Clayey Silts
O Input Your Own Permeability Range

5) Click button to calculate Predicted Flowrat Ranges

Permeability Range (darcy)
Cit

Well Radius C2 jin
Radius of Influence [_40_|ft
Interval Thickness* [_6.6__]ft

(_—>Calculate Flowrate Ranges<— )

‘© thickness of seruanad interval, or &
zone (whichever is small

#6»
Figure 12. Card 8 of the."Soil Venting Stack" stack.

Step 3: Location: Card 8 of the “Soil Venting Stack" stack.
Action: Choose the "Fine Sand" soil type, and enter:

well radius = 2in

radius of influence= 40 ft
interval thickness = 6.6 ft

user input vacuum= 200 in H2O0

into the appropriate fields, then click on the
".->Calculate Flowrate Ranges<--" button.

Result: | The flowrate ranges are calculated and displayed. Your screen
should now look like Figure 12. The calculated values are estimates
of the flowrate to a single vertical well (and are only valid estimates
when your conditions are consistent with the assumptions built into
the calculation - see Johnson et al. [1990a, b] for more details).

Step 4: Location: Card 8 of the "Soil Venting Stack” stack.
Action: Click on the right pointing arrow to advance to card 9. Read the
information on this card, then advance to card 10
Result: You are now at card 10 of the "Soil Venting Stack” stack (see Figure
13).

Step 5: Location: Card 10 of the "Soil Venting Stack" stack.
Action: Assume that the soil temperature at our sample site is 18° C. Enter |
this value in the appropriate field, then hit the “return” key. This
action clears all values from the other fields.



- HyperVentilate Users Manual -

References

Hutzler, N. J., Murphy, B. E., and Gierke, J. S., State of Technology Review:
Soil Vapor Extraction Systems, U.S.E.P.A, EPA/600/2-89/024, June 1989.

Johnson, P. C., Kemblowski, M. W., and Colthart, J. D., Practical Screening
Models for Soil Venting Applications, NWWA/API Conference on Petroleum
Hydrocarbons and Organic Chemicals in Groundwater, Houston, TX, 1988.

Johnson, P. C., Stanley, C. C., Kemblowski, M., W., Byers, D. L., and
Colthart, J. D., A Practical Approach to the Design, Operation, and Monitoring of
In Situ Soil Venting Systems, to appear in Ground Water Monitoring Review,
Spring 1990.

Marley, M. C., and Hoag, G. E., Induced Soil Venting for the
Recovery/Restoration of Gasoline Hydrocarbons in the Vadose Zone, NWWA/API
Conference on Petroleum Hydrocarbons and Organic Chemicals in Groundwater,
Houston, TX, 1984.

Marley, M. C., Baehr, A. L., and Hult, M. F., Evaluation of Air-Permeability in
the Unsaturated Zone using Pneumatic Pump Tests: 1. Theoretical Considerations,
in review, 1990.

Thornton, J. S. and Wootan, W. L., Venting for the Removal of Hydrocarbon
Vapors from Gasoline Contaminated Soil, J. Environ. Sci. Health, A17(1), 31-44,
1982.

Newell, C. J., Haasbeek, J. F,, and Bedient, P. B., OASIS: A Graphical Decision
Support System for Ground-Water Contaminant Modeling, Ground Water, 28 (2),
224 - 234, March - April 1990.



- HyperVentilate Users Manual -

Critical Volume Calculation...

typically observed in venting
operations.

cine (t=0)

‘The results are plotted in this way ©

emphasize that the degree of

remediation that can be achieved by

venting depends mainly on the

volume of vapor extracted divided

by the inital mass of residual

Ihydzocarbon. For the example

pictured at the right, approximately

100 liters of sir must be withdrawn

from the subsurface in order to a a 200

remove about 90% of a sin
Qvm(t=0) (a)
Do a Calculation

‘

Figure 29. Card SDS of the "System Design" stack.

Critical Voiume

Predictions... © Enter Distribution
‘Simply enwr the wmperature ot ~ O "Fresh" Gasoline.

the rightand then specify te j @ "Weathered" Gasolina
mavccton secon

If you are unsure about this, click

on the “About Composition..."
roonbeatsermerean | © feneues

Hi} =50
238.
allows you w determine iis i 80.
residual amounts of LL
compounds falling within S 144
boiling point ranges. Type in
your own ranges, or choose

he defactt valves.

Figure 30. Card SD6 of ti the syster Design" stack.
v



vapors, but this in itself does not rule out the possibility
that O, is converted to CO before the vapors pass
through the contaminated soil zone. The best approach
is to measure the O2/CO, concentrations in the vapors
at the edge of the contaminated zone, and in the vapor
extraction wells. If the CO2/O, concentration ratio
increases as the vapors pass through the contaminated
soil, one can surmise that a transformation is occurring,
although other possible mechanisms (inorganic reac-
tions) must be considered. An increase in aerobic mic-

robial populations would be additional supporting evid-_

ence,
In Situ Heating/Venting

The main property of a compound that determines
whether or not it can be removed by venting is its vapor
pressure, which increases with increasing temperature.
Compounds that are considered non-volatile, therefore,
can be removed by venting if the contaminated soil is
heated to the proper temperature. In situ heating/vent-
ing systems utilizing radio-frequency heating and con-
duction heating are currently under study (Dev et al.
1988). An alternative is to reinject heated vapors from
catalytic oxidation or combustion units into the con-
taminated soil zone.

Air Sparging
Due to seasonal ground water rlevel fluctuations, con-

taminants sometimes become trapped below the water
table. In some cases ground water pumping can lower
the water table enough to expose this zone, but in other
cases this is not practical. One possible solution is to
install air sparging wells and then inject air below the
water table. Vapor extraction wells would then capture
the vapors that bubbled up through the ground water.
To date, success of this approach has yet to be demon-
strated. This could have a negative effect if foaming,
formation plugging, or: downward migration of the tesid-
ual occurred.

Application of the Design Appejech .
to a Service Station Remediation.

In the following, the use of the approach discussed
previously and outlined in Figure 2, is demonstrated for
a service station’ remediation.

Preliminary Site Investigation
Prior to sampling it was estimated that 2000 gallons
of gasoline had leaked from a product line at this operat-
ing service station site. Several soil borings were drilled
and the soil samples were analyzed for total petroleum
hydrocarbons (TPH) and other specific compounds
(benzene, toluene, xylenes) by a heated-headspace
method utilizing a field GC-FID. Figure 15 summarizes
some of the results for one transect at this site. The
following relevant information was collected:
© Based on boring logs there are four distinct soil layers
between 0 — 18m (0 - 60 ft) below ground surface
(BGS). Figure 15 indicates the soil type and location
of each of these layers.
@ Depth to ground water was 15m, with fine to medium
sand soils.

0

4
n

8

Diaunee Below Ground Surface (8)

ot
\
Suaic Grownd
HB-21 Recovery
Recovery Well) * suzy
° 0 #

Figure 15. Initial total hydrocarbon distribution [mpfkg-soil]
and location of lower zone vent well.

© The largest concentrations of Tyavocarbons were
detected in the sandy and silty clay layers adjacent
to the water table. Some residual was detected below
the water table. Based on the data presented in Figure
15 it is estimated that ~ 4000kg of hydrocarbons are
present in the lower two soil zones.
Initially there was some free-liquid gasoline floating
on the water table: this was subsequently removed
+ by pumping. A sample of this product was analyzed
and its approximate composition (~20 percent of the
compounds could not be identified) is listed in
Table 2 as the “weathered gasoline.” The corre-
sponding boiling point distribution curve for this mix-
ture has been presented in Figure 3.
® Vadose zone monitoring installations similar to the
one pictured in Figure 14 were installed during the
preliminary site investigation.

Deciding if Venting Is Appropriate

For the remainder of the analysis the contaminated
soils located just above the water table will be the focus.
@ What contaminant vapor concentrations are likely to

be obtained?

Based on the composition given in Table 2, and using
Equation 1, the predicted saturated TPH vapor concen-
tration for this gasoline is:

Cen = 220 mg/L

Using the “approximate” composition listed in Table
2 yields a value of 270 mg/L. The measured soil-vapor
concentration obtained from the vadose zone monitoring
well was 240 mg/L. Due to composition changes with time,
this will be the maximum concentration obtained during
venting.

@ Under ideal flow conditions is this concentration great
enough to yield acceptable removal rates?



"Soil Venting Stack* Cards

Click to Enter Composition of Contamimeant © Enter Distribution
or O “Fresh” Gesoline ,
Choose one of the Defautt Distributions @ “Weathared* Gasoline
(Wecaruke Gi “marinen’ mmovl me © ésemnte

5 y ao (f, oven under te best conditions (semmmated vapors &
C3) Stick to View Distributions, (optional) C Distributions: issu ‘to componttion changes wins), venting cen meet,
out nests.

(Cite cm the bute below w genset tae vetoes...



- HyperVentilate Users Manual-__.

Number of Venting Wells...

Just proceed to follow the steps dictated on.
the folowing cards-—-> id

t 4

Figure'5. Card SD1 of the "System Design" stack.

V.3. Sample Problem Exercise

In the following a sample problem is executed in excruciating detail. Those not wishing to
work along with the example are encouraged to utilize Appendices A through F as
references for more details on the less obvious functions of some cards.

This "Sample Problem Exercise" is divided into to four subsections that address: navigating
through HyperVentilate (§V.3.1), screening sites to see if soil venting is an appropriate
technology (§V.3.2), interpreting air permeability test data (§V.3.3), and guidance for
designing soil venting systems (§V.3.4).

V.3.1 Navigating Through HyperVentilate

Step 1: Location: The “Desktop” or Finder.
Action: Start-up HyperVentilate by double-clicking on the "Soil Venting
Stack” icon, or click once on this icon and then choose “Open" from
the "File” menu. .
Result: | HyperVentilate will start-up and display the title card (Figure 2).

Step 2: Location: Title Card of the "Soil Venting Stack” stack.

Action: . Click on the "About This Stack" button. -

Result: | You are now at card H1 of the "Soil Venting Help Stack" stack
Figure 3).





"Soil Venting Help Stack” Cards

Extraction Well Vapor Composition.

Soll Gus Monitoring
Installation Results



“Soil Venting Help Stack” Cards Bs

[zs ]
Help: 6c) Low Permeability Lenses Help: 6c) Low Permeability Lenses - Equations

Help: Default Boiling Point Ranges

‘The Fortran program HYPEVENT will report residual levels of compounds
falling between user specified boiling point ranges, The default values have
bboea choten £0 that residual levels of compounds with boiling points between
the following compounds are grouped together:

Heip: Boundary Layer Equations

Rea = 1QCon
tm p(t) ToC YR SY Pan - Pol? AE RT

ceamued removal re

‘= efficiency lative to maxima removal rap

‘= cocaive pall vapor diffusion conffivient (crn2/s]
‘viscosity of air = 1.8 x 10-4 gis

Proptne - Isopentane (-50 10 28 C)

Isopentane - Benzene (28 10 80 C)

Benzene - Toluene (80 - 111 C)

Toluene - Xyienes (111 - 144C)

‘= ebeclut ambient preanire = 1.016 x 106 g/an-62
Xylenes - Methylnapthalene (144 - 250C)

Pe =abeclue promur atte wating well [shem2]
cere = defies region in which contamination Se prseat

(Help: Boundary Layer quations - Calculation

KL) Solt Type (choose one) [Tust enter values into the ay © CS tm =7
OMetinn ses O Cayey Sus appropriate fields, then click on _

Osan Sma @ Pine Send the “calcalate” button, Time Remeval
© toput Your Own Permeabiiy Range . 7 i (days) (ke/a)
5 to CS teareyst ra ef te predicted exer TREES
@ Process Variables: $95,

© sae valuce already input from Card 10

Crass) Tost enter valuce into the appropriate Siclds, ta
Relative Emitency = Cass) tick on te *Caleatem” baton,
%)

upwelling”, or local rise in the
water table will occur.

The local water table rise can be

g] Gromé Warr Level (Grud Water Level
Before Sum of Venting After Stutof Venting



“Air Permeability Stack" Cards

|Air Permeability Test - Data Analysis (cont.)

[Ge th previous Can (APE), tio dus you input were Git wo the approximate expreanion piven ou Cand
APS. 1k was exetyand wting both methods dcactibed on card AP7. if you input vaines for ths
exumction well fowrnss (Q) and th sextum thicken (m). Below each cofaams of dam, tho Two
 caicalatd permeability vues re dence by:

aarey{A) - rfera w calcalation method 1 (ae Card APT)
 dary(B)- refer we calcalaten meshod 2 (ace Cand APT)

c2




“Soil Venting Help Stack” Cards B2

can leach, or limit the solubility of
hazardous constivents. When
discussing this technology, the’ E
following definitions ere common:

"Nove that k denotes te “permeability” of a porous
‘media, while K presen the “hydruatic
comducaiviry”. The two are rand by

Kak M08
co aakp, {t= Pam! Pe)
ve

In (Ry /Ry)
(¢ + ecouenton de © party [OO cts")
Pup = Hiacnaty of wane [0.01 gene] = ool permeability w ar flow fer?) or [dacy}
Pap ® densty of wens (1.0 gem?) HM & vinconity of air = 1.8 x 10 glom-0 or 0.018 op
Ry = sbeotots pease at extraction well Lg/cm-s2] or (atm)

‘chooeing pan y Rag shectom ambient preenure = 1.01 2 10° pcan-e or 1 sim
import to orp in mind that (08 X) Ry © rine of vapor extraction weil fom)
aceon Ry = nding of infnencs of vapor extraction well {c=}

Ho thicken of well roe inmerval 2 oil nas (cboase ecaliet value)

” 7 |



- HyperVentilate Users Manual -

Step 10:

Step 11:

Result:

Location:
Action:

Result:

Location:
Action:

Result:

Your screen should now look like Figure 16. Note that your desired
removal rate (=22 kg/d) is less than the estimated maximum removal
rates for a single vertical well (=165 to 1650 kg/d). At this point in
the screening exercise, therefore, soil venting still appears to be a
viable option. . :

Card 13 of the "Soil Venting Stack” stack.

Click on the right-pointing arrow button to advance to card 14 of the
"Soil Venting Stack" stack. Read the text, then advance to card 15
of the "Soil Venting Stack” by clicking on the right-pointing arrow
button. Again, take the time to read the text, then advance to card 16
of the "Soil Venting Stack" stack. The focus of these cards is the
prediction of vapor concentrations and removal rates as they change
with time due to composition changes. It is important to try to
understand the concepts introduced in these cards.

You are at card 16 of the "Soil Venting Stack" stack (see Figure 17).

Card 16 of the "Soil Venting Stack" stack.

This card is used to finalize your input data prior to calculating vapor
concentration and residual soil contamination composition changes
with time. Read the instructions in the order that they are numbered.
Note that the summary table in the upper right corner of the card
contains all the parameter values that you have input thus far. The
instructions describe how to change these values, but at this point
we will retain the displayed values. - Because it is difficult to present
the behavior of each compound in a mixture composed of an
arbitrary number of compounds, the output is simplified by
reporting the behavior in terms of "boiling point" ranges. This
simply represents a summation of all compounds whose boiling
points fall between pre-specified values. Presented in this fashion,

the model results can be interpreted much more quickly. Click on

the "tell me more about BP ranges..." button, read the help card,
then return to card 16 of the "Soil Venting Stack" stack. Click on
the "-->Set Default BP Ranges<--" button. Your screen should now
look like Figure 17. Click on the "Generate Predictions" button

The message "Sit Back and Relax..." will appear on your screen,
followed by a screen on which the following appears:

"Copyright © Absoft Corp 1988

Copyright © Shell Oil Co 1990

HANG ON ----- YOU WILL BE RETURNED TO HYPERCARD...

# OF COMPOUNDS IN LIBRARY = 62"
Then card 17 of the "Soil Venting Stack” stack will appear.





‘This card i
Lis. Dua.

ided as. to let you
mines

“Compound List Update" Stack Cards

add, or delete:

[Molecetar Weight [g/mote]
Vapor Preware @20C {stm}
Boiling Point @1 atm (C]

Ft



_- HyperVentilate Users Manual -

Disclaimer

Shell Oil Co. makes no warranties, either express or implied, regarding the
enclosed computer software package, its merchantability, or its fitness for
any particular purpose. Shell Oil Co. does not warrant that this software
will be error free or operate without interruption. The exclusion of implied
warranties is not permitted by some states. The above exclusion may not
apply to you. This warranty provides you with specific legal rights. There
may be other rights that you may have which vary from state to state.

Apple is a registered trademark of Apple Computer, Inc.
Macintosh and HyperCard are trademarks of Apple Computer, Inc.

£77.11 is a product of Absoft Corp

Comments/Suggestions?
Comments and/or suggestions about the usefulness of this program can be mailed to:

Paul C. Johnson
Shell Development
Westhollow Research Center
P.O. Box 1380
Room EC-649
Houston, TX’ 77251-1380

Please do not call the author and/or Shell with questions about the use or
interpretation of results from this program.





- HyperVentilate Users Manual -

Appendix G: Reprint of:

"A Practical Approach to the Design, Operation, and
Monitoring of In Situ Soil Venting Systems"



terize and delineate the zone of soil afid ground water
contamination. In general, the site characterization is
conducted in two stages. The emergency response and
abatement phase assesses the immediate impact on
potential human and environmental receptors, and is
conducted in a relatively short period of time (days). A
detailed site characterization then follows. Its purpose,
like the emergency response and abatement phase, is
to determine potential migration pathways and assess
the environmental impact associated with present condi-
tions and future migration of the contaminants. Often
the sequence of steps following initial response and
abatement is as follows:
@ Background review: Involves assembling historical
records, plot plans, engineering drawings (showing
utility lines), and interviewing site personnel. This
information is used to help identify the contaminant,
probable source of release, zone of contamination,
and potentially impacted areas (neighbors, drinking
water supplies, etc.).
Preliminary site screening: Preliminary screening
tools such as soil-gas surveys and cone penetrometers,
are used to roughly define the zone of contamination
and the site geology. Knowledge of site geology is
essential to determine probable migration of conta-
minants through the unsaturated. zone.

© Detailed site characterization: Soil borings are drilled
and monitoring wells are installed.

© Contaminant characterization: Soil and ground water
samples are analyzed to determine contaminant con-
centrations and compositions.

Costs associated with site investigations can be rela-
tively high depending on the complexity of the site and
size of the spill or leak. For large spills and complex
site geological/hydrogeological conditions, site investi-
gation costs may begin to approach remediation costs.
In addition, the choice and design of a remediation
system is based on the data obtained during the site
investigation. For these reasons it is important to ensure
that specific information is collected, and to validate the
quality of the data.

If it is presumed that in situ soil venting will be a
candidate for treatment, then the following information
needs to be obtained during the preliminary site investi-
gation: .

@ Subsurface characteristics — site geology: This
includes the determination of soil stratigraphy (va-
dose and saturated zone) and characteristics of dis-
tinct soil layers (i.e., soil type, permeability estimates).
While they are not essential, the moisture content,
total organic carbon, and permeability of each distinct
soil layer also provides useful information that can
be used to choose and design a remediation system.

© Subsurface characteristics — site hydrogeology:
Depth to ground water, and the ground water gradi-
ent must be known, as well as estimates of the aquifer
hydraulic conductivity. .

© Contaminant delineation: The distribution of con-
taminants in the saturated and vadose zones needs
to be assessed. This includes the extent of the free-
phase hydrocarbon, residual hydrocarbon, and solu-

~— Vapor Extraction Well
Vi
vi — <a Vapor
row oe Contaminated —— Flow
— Soil _ Free-Liquid
Hydrocarbon
Groundwater Table Soluble
Plume

Figure. 1. “Basic" in situ soil-venting system.

Process Output

Leak or Spilt Discovered Background Review
‘Site Characteristics:
‘Emergency Response & Abaicment on

"oat deanraghy
‘character of doin! sod layers

spermesbinty estimates, sol types)
<depihio groundwater

a [Eoenal wate able Mactushons
T7|__ Characterization 77] Sater pemeatty (ema) *
: ‘Eabore ound
Exposure Ancsanent contain ution .
{onan of omtarnat nad fo’
Regulatory Review Tentet ofslcble cota ple
+ empoeton of eanamioun
he 1 vapor concertion (non)
Receptabie > 7
Ye.
No
{emediation Needed
NoFunher Yer
‘Action
Define Ciean-up Objectives
‘Screen Treatment

Alternatives

t

aie permeability of haunct wid layers
{talus ofnuence of vapor wells
‘inal vape concerns

‘System Shut-Off
Figure 2, In situ soil-venting system design process.


~ HyperVentilate Users. Manual -

Design Input Parameters...
(soil stratigraphy & contaminant characteristics)
Please enter the required information for each distinct soil

Select the oul mess @ [ke]
‘units that you prefer © [ih]

. (Clear All Enuies_)
layer, click on the “Update” button, and then proceed Cisar All Entries

‘the next cand (i.e. click on right arrow et bottom). ‘Contaminant
Distribution
‘ipterval | average
Depth BGS* divs hehickness| come.
In} [mois]

tw)

199,

20.
20. 1000,
20. 10000.

fe seoiaisiccic

+ Ex »

Design Input Parameters... [Now:- click on eny ubie heading 0] © Metium fant

Please enter the required information for
each distinct soil layer, and then proceed
fw the nextcard. .

Description of Permeability .
Soil Unit ,

[Medium Sand 10. 100,

| Clavey, Sitt_ 9.01 1

Fine Sand, 1 10

‘Eater of choose from List at top righ ‘+ minimum volune of vapor mquired to achieve remediation
Ga « =

Figure 28. Card SD3 of the "System Design" stack.

Vv ‘

324-235 0 - 92 - 3 QL 3

29


- HyperVentilate Users Manual -

Vapor Concentration Estimation - Calculation

(2) Type in Temperature (*C) (hit <return>)
Click to Enter Composition of Contaminant . © Enter Distribution
@o : ; O “Fresh” Gasoline
Choose one of the Default Distributions @ "Weathered" Gasoline
CF) Click to View Distributions, (optional)

C4) Click to Perform Calculations @ Perform Calculations

‘Sum of Mass Fractions © 1.00000
Results: Calc. Vapor Pressure
. . Calc. Vapor Concentration 203.94878

Gm «le [Pinca

Figure 13, Card 10 of the "Soil Venting Stack" stack.

LHi6 |
Help: Compound List re] j
[View Only Mode} tase

# Compound Name Fraction Weight (g)
propane 0.00 44.1
isobutane a 0.00 58h
n-butane 0 58.1
trans-2-butene 0 56.1 |
cis-2-butene 0 56.1 1.67019
3-methyl-1-butene 0 70.1 0.88399
isopentane 0.0069 72.2 0.73146
1-pentene , [0.0005 70.1 0.64989
2-methyl-1-butene 0.0008 70.1 0.62093
2-methy!-1,3-butadiene 0.0000. [68.1 0.60914
= Sumof Mess Frections
(should be =1)

Return w Vapor Cone. Estimation Card

= Oa IaAnhane|

Figure 14. Card H16 of the "Soil Venting Help Stack” stack.

Vv



- HyperVentilate Users Manual -

Step 14: . Location: Card 18 of the "Soil Venting Stack" stack.
Action: Click on the right-pointing arrow button to advance to card 19.
Result: You are now at card 19 of the "Soil Venting Stack" stack. This card
lists several phenomena that can cause one to achieve less than ideal
removal rates. Take the time to explore each of. these options, then
return to card 19 of the "Soil Venting Stack" stack. ©

Is Veating Appropriate?

This is a complete summary [O)

ofthe data and ert Eel Coney (resis Sie
Contaminant Type: Weathered Gasoline.
a Soll Type: Fine Sand

‘1 4 ‘Well Radius in}:
as been calculated, which Est. Radius of Tnence itu: zn
should give you some Permeable Zone Thickness [ft]: [___6.6
indication of how Flowrate per Well (120" Vac) [SCFM] 6.83
appropriate venting is for itll Flowrate per Well (120" Vac) [SCFM] 68.27
your application. Note that Min. Vol. of Air [Lig-residual]):
this is the number of wells if |, | Estmatd Spill Mess: 4000
circumstances are ideal, Desired Remediation Time (days): - 180

Minimun £ of Wells
(oom ese <a

on Your Input Parameters

18)

Figure 19, Card 18 of the "Soil Venting Stack” stack.



- HyperVentilate Users Manual -

Maximum Removal Teaperure ce)
Rate Estimates Sofl Permesdility Renge (darcy)

Well
select reference below. Radius of Influence (£9
sort Contaminant
@ [Ib/d] . Permeeble Zone Thickness (f1)

O lkg/dl - Well’ - Flowrat: Estimates Mex. Removal Rate Estimates
Noe: Vacuum [SCFM] Ula]
° GnH20) + (single vell) (single well)

these are “maximum 033 332 62.
removal rots”, end shoud | }.10_ |}. 0.66 6.59 124
Y 20 | A302 _ >)
40.
$0 mn 3Z99, 799.

1 68.27.
20) - 3636

Figure 15. Card 12 of the “Soil Venting Stack" stack.

Js Soil Venting Appropriate? rnter @kg
At this point, you compare the @® Estimated Spill Mass[__ 4000) © 1p

maximuin possible removal rate Ld Enter Desired
‘vith your desired removal rate. @ Remediation Time days

1 demain envel can: || * © Crarearin=)

does not exceed your desired
removal rate, then soi! venting Single Vertical Well Results

is not likely to meet your needs, 7

land you should consider another Gauge Vacuum, me 120): : 22, iano]
treatment technology, or make MinFlown @ 200 int20[_10.07] [scrm)
your needs more realistic. Max Fiowne @ 200 inH20|_ 100.66] [scrM]
Max. Est. Removal Rate:
In the next cards, ve will refine }!!4| (lower estimate) - per well 164.892] [kerd)
> it cy| (Upper estimate) - per well 1647.108 } [kg/d]

Figure 16. Card 13 of the "Soil Venting Stack" stack.



- HyperVentilate Users Manual -

Step 8:

Step 9:

Result:

Location:

Action:

Result:

Location:
Action:

Result:

The “Critical Volume of Air" is calculated by the same procedure
used previously in §V.3.2 (steps 10 -13). To initiate this
calculation, "click" on the "Critical Volume of Air**" heading.

Card SDS of the "System Design" stack appears on your screen
(Figure 29). .

Card SDS of the "System Design" stack.

Read the text carefully. The focus of this card is the prediction of
vapor concentrations and removal rates as they change with time due
to composition changes. It is important to try to understand the
concepts introduced in this card. For more information, read the
reference article contained in the appendix. Click on the "Do a
Calculation” button to advance to card SD6 of the "System Design"
stack (Figure 30).

Card SD6 of the "System Design” stack appears on your screen.

Card SD6 of the "System Design” stack.

This card is used to finalize your input data prior to calculating vapor
concentration and residual soil contamination composition changes
with time. Read the instructions in the order that they are numbered,
then enter "18" for the temperature and select "weathered gasoline”
from the three composition options. Because it is difficult to present
the behavior of each compound in a mixture composed of an
arbitrary number of compounds, the output is simplified by
reporting the behavior in terms of “boiling point" ranges. This
simply represents a summation of all compounds whose boiling
points fall between pre-specified values. Presented in this fashion,
the model] results can be interpreted much more quickly: Click on
the "tell me more about BP ranges..." button, read the help card,
then return to card SD6 of the "System Design” stack. Click on the
"-->Set Default BP Ranges<--” button. Your screen should now
look like Figure 30. Click on the "Generate Predictions" button

The message "Sit Back and Relax..." will appear on your screen,
followed by a screen on which the following appears:

“Copyright © Absoft Corp 1988

Copyright © Shell Oil Co 1990

HANG ON ----- YOU WILL BE RETURNED TO HYPERCARD...

# OF COMPOUNDS IN LIBRARY = 62”

Then card SD7 of the "System Design” stack will appear as shown
in Figure 31.



- HyperVentilate Users Manual -

V.3.2 Sample Problem Exercise - Is Venting Appropriate?

In §V.3.2. you will work through an example problem to illustrate how one might decide if
venting is appropriate at any given site. For the purpose of this example we will use the
example site information given in Figure 10.

North South
= .
4 Sandy
Te Clay os oat
location) :
wy - pe p---- 46-2 — 1
0.02 03 dow
Fine to
> Dm rT? Coarse Sand 82 017
2 qn 0.0 ne 1.
d
Any — doe J--- 31 he 0.63
[ T° Silty Clay 967 15
& 40 bis Clayey Silt on Lose
3 -4-4f--—--—--—-— 28699 a 3
A +e Le
a 50 ml Yi Fine to. 23167 +32V
Medium Sand :
17
ot | Los ¥ ;
HB-17 HB-10° HBS HB-3
Static Ground
Water Table

SCALE (fi)
——}.-__..]
0 10 20

Contamination Type: Weathered Gasoline

Figure 10. Sample site data (Johnson et al. [1990a]). Total petroleum hydrocarbons
(TPH) [mg/kg] values are noted for each boring.



increase by 15 percent when the extraction well diameter
is increased from 10cm (4 in) to 20cm (8 in). This implies
that well diameters should be as large as is practically
possible. .

A typical well as shown in Figure 13a is constructed
from slotted pipe (usually PVC). The slot size and num-
ber of slots per inch should be chosen to maximize the
open area of the pipe. A filter packing, such as sand or
gravel, is placed in the annulus between the borehole
and pipe. Vapor extraction wells are similar to ground
water monitoring wells in construction but there is no
need to filter vapors before they enter the well. The
filter packing, therefore, should be as coarse as possible.
Any dust carried by the vapor flow can be removed by
an above-ground filter. Bentonite pellets and a cement
grout are placed above the filter packing. It is important
that these be properly installed to prevent a vapor flow
“short-circuiting.” Any ground water monitoring wells
installed near the extraction wells must also be installed
with good seals.

Vapor Treatment
Currently, there a four main treatment processes
available:

@ Vapor combustion units: Vapors are incinerated and
destruction efficiencies are typically >95 percent. A
suppleméntal fuel, such as propane, is added before
combustion unless extraction well vapor concentra-
tions are on the order of a few percent by volume.
This process becomes less economical as vapor con-
centrations decrease below ~ 10,000 ppm,.

© Catalytic oxidation units: Vapor streams are heated
and then passed over a catalyst bed. Destruction effi-
ciencies are typically >95 percent. These units are
used for vapor concentrations <8000 ppm,. More con-
centrated vapors can cause catalyst bed temperature
excursions and meltdown.

© Carbon beds: Carbon can be used to treat almost any
vapor streams, but is only economical for very low
emission rates (<100 g/d)

© Diffuser stacks: These do not treat vapors, but are
the most economical solution for areas in which they
are permitted. They must be carefully designed to
minimize health risks and maximize safety.

Ground Water Pumping System

In cases where contaminated soils lie just above or
below the water table, ground water pumping systems
will be required to ensure that contaminated soils
remain exposed. In designing a ground water pumping
system it is important to be aware that upwelling (draw-
up) of the ground water table will occur when a vacuum
is applied at the extraction well (see Figure 9b). Because
the upwelling will be greatest at the extraction wells,
ground water pumping wells should be located within
or as close to the extraction wells as possible. Their
surface seals must be airtight to prevent unwanted short-
circuiting of airflow down the ground water wells.

System Integration
System components (pumps, wells, vapor treating

units, etc.) should be combined to allow maximum flexi-

bility of operation. The review by Hutzler et al. (1988)

provides descriptions of many reported systems. Specific

requirements are:

® Separate valves, flow meters, and pressure gauges for
each extraction and ‘injection well.

© Air filter to remove particulates from vapors
upstream of the pump and flow meter.

®@ Knock-out pot to remove any liquid from vapor
stream upstream of the pump and flow meter.

Monitoring .

The performance of a soil-venting system must be
monitored in order to ensure efficient operation, and
to help determine when to shut off the system. At a
minimum the following should be measured:
© Date and time of measurement.
© Vapor flow rates from extraction wells and into injec-

tion wells: These can be measured by a variety of
flow meters including pitot tubes, orifice plates and
rotameters. It is important to have calibrated these
devices at the field operating pressures and tempera-
tures.
© Pressure readings at each extraction and injection
well can be measured with manometers or magnahelic
gauges.
© Vapor concentrations and compositions from extrac-
tion wells: total hydrocarbon concentration can be
measured by an on-line total hydrocarbon analyzer
calibrated to a specific hydrocarbon. This information
is combined with vapor flow rate data to calculate
removal rates and the cumulative amount of contam-
inant removed. In addition, for mixtures the vapor
composition should be periodically checked. It is
impossible to assess if vapor concentration decreases
with time are due to compositional changes or some
other phenomena (mass transfer resistance, water.
table upwelling, pore blockage, etc.) without ‘this
information. Vapor samples can be collected in evacu-
ated gas sampling cylinders, stored, and later ana-
lyzed.
Temperature: ambient and soil.
Water table level (for contaminated soils located near
the water table): It is important to monitor the water
table level to ensure that contaminated soils remain
exposed to vapor flow. Measuring the water table
level during venting is not a trivial task because the
monitoring well must remain sealed. Uncapping the
* well releases the vacuum and any effect that it has
on the water table level. Figure 13b illustrates a moni-
toring well cap (constructed by Applied Geosciences

Inc., Tustin, Catifornia) that allows one to simulta-

neously measure the water table level and vacuum in
a monitoring well. It is constructed from a commer-
cially available monitoring well cap and utilizes an
electronic water level sensor.

Other valuable, but optional measurements are:

© Soil-gas vapor concentrations and compositions:
These should be measured periodically at different
radial distances from the extraction well. Figure 14



Reprinted from the Spring 1990 Issue of
Ground Water Monitoring Review

A Practical Approach to the Design,
Operation, and Monitoring of In Situ-
Soil-Venting Systems

by P.C. Johnson, C.C. Stanley, M.W. Kemblowski, D.L. Byers, and J.D. Colthart

Abstract

When operated properly, in situ soil venting or vapor extraction can be one of the most cost-effective remediation
processes for soils contaminated with gasoline, solvents, or other relatively volatile compounds. The components of
soil-venting systems are typically off-the-shelf items, and the installation of wells and trenches can be done by
reputable environmental firms. However, the design, operation, and monitoring of soil-venting systems are not
trivial. In fact, choosing whether or not venting should be applied at a given site is a difficult decision in itself. If
one decides to utilize venting, design criteria involving the number of wells, well spacing, well location, well construc-
tion, and vapor treatment systems must be addressed. A series of questions must be addressed to decide if venting
is appropriate at a given site and to design cost-effective in situ soil-venting systems. This series of steps and questions
forms a “decision tree” process. The development of this approach is an attempt to identify the limitations of in
situ soil venting, and subjects or behavior that are currently difficult to quantify and for which future study is needed.

Introduction

When operated properly, in situ soil venting or vapor
extraction can be a cost-effective remediation process
for soils contaminated with gasoline, solvents, or other
relatively volatile compounds. A “basic” system, such
as the one shown in Figure 1, couples vapor extraction
(recovery) wells with blowers or vacuum pumps to
remove vapors from the vadose zone and thereby reduce
residual levels of soil contaminants. More complex sys-

tems.incorporate trenches, air injection wells, passive

wells, and surface seals. Above-ground treatment sys-
tems condense, adsorb, or incinerate vapors; in some
cases vapors are simply emitted to the atmosphere
through diffuser stacks. In situ soil venting is an espe-
cially attractive treatment option because the soil is
treated in place, sophisticated equipment is not
required, and the cost is typically lower than other
options.

The basic phenomena governing the performance of
soil-venting systems are easily understood. By applying
a vacuum and removing vapors from extraction wells,
vapor flow through the unsaturated soil zone is induced.
Contaminants volatilize from the soi! matrix and are
swept by the carrier gas flow (primarily air) to the extrac-
tion wells or trenches. Many complex processes occur
on the microscale, however, the three main factors that
control the performance of a venting operation are the
chemical composition of the contaminant, vapor flow
rates through the unsaturated zone, and the flow path
of carrier vapors relative to the location of the contamin-
ants.

The components of soil-venting systems are typically

off-the-shelf items, and the installation of wells and
trenches can be done by reputable environmental firms.
However, the design, operation, and monitoring of soil-
venting systems is not trivial. In fact, choosing whether
or not venting should be applied at a given site is a
difficult question in itself. If one decides to utilize vent-
ing, design criteria involving the number of wells, well
spacing, well location, well construction, and vapor
treatment systems must be addressed. It is the current
state-of-the-art that such questions are answered more
by experience than by rigorous logic. This is evidenced
by published soil venting “success stories” (see Hutzler
et al. 1988 for a good review), which rarely include
insight into the design Process.

In this paper, a Series of questions are presented that
must be addressed to:

© Decide if venting is appropriate at a given site.

© Design cost-effective in situ soil-venting systems.
This series of steps and questions forms a “decision
tree” process. The development of this approach is an
attempt to identify the limitations of in situ soil venting,
and subjects or behavior that are currently difficult to
quantify and for which future study is needed.

The “Practical Approach”

Figure 2 presents a flow chart of the process dis-
cussed in this paper. Each step of the flow chart will be
discussed in detail, and where appropriate, examples
are given.

The Site Characterization
Whenever a soil contamination problem is detected
or suspected, a site investigation is conducted to charac-





- HyperVentilate Users Manual -

Il. Definition of Some Terms Appearing in this Manual

button - an object on a “card” that causes some action to be performed when
"clicked" on

card - an individual screen that you view on your monitor

click - refers to the pressing and releasing of the button on your mouse

drag - refers to holding down the mouse button while moving the mouse

field - atext entry location on a "card"

HyperCard - a programming environment created by Apple Computer, Inc.

mouse - the device used to move the cursor within your monitor

select - ‘efers to "dragging" the cursor across a “field”

stack - ~ agroup, or file, of "cards" :

Ill. Software/Hardware Requirements

Apple Macintosh HyperVentilate version 1.01 requires an Apple Macintosh (or
equivalent) computer equipped with at least 1 MB RAM (2 MB preferable), a hard disk,
and the Apple HyperCard Software Program (v 2.0). Check to make sure that your
system software is compatible with your version of HyperCard. ,

IV. Loading HyperVentilate Software

. HyperVentilate is supplied on an 800 kB double-sided, double density 3.5" diskette.
Follow the instructions listed below to insure proper operation of the software.

1) Insert the HyperVentilate disk into your computer's floppy drive. The
Hyper Ventilate disk should contain the files:

_ > "Soil Venting Stack"
- "Soil Venting Help Stack"
- "System Design”
- "Air Permeability Test"
- "Aquifer Characterization”
- "Compound List Update"
- “HypeVent"
- "£77.11"

2) Copy these files onto your hard disk. They must be copied into the folder
that contains the "HyperCard" program, or else the software will not
operate properly.

3) Eject the HyperVentilate disk



- HyperVentilate Users Manual -

System Design...

At the right is a list of the components ONumber of Extraction Wells
of a venting system design. Click on 7
each to conduct the indicated phase of O Well Location
the design process

Remember: It is not our intention to provide a
generic recipe for vacuum extraction sysem O Surface Seals
design; insted we suggest the following a3 a

‘structured thought process. As you shall see, .
even ina structured thought process, intuition | © Groundwater Pumping System
and experience play important roles. There is °

no substitute for a good fundamental O Vapor Treatment
‘wlerstanding of vapor flow processes,
‘wansport phenomena, end groundwater flov!

© Well Construction

Figure 25. Card 24 of the "Soil Venting Stack" stack.

Number of Venting Wells...

venting is eppropriat ata given site.

As illustrated at the right, we willestimate
single vertical well flowrates, calculate the

Just proceed to follow the steps dictated
‘the following cards--->

Figure 26. Card SD1 of the "System Design" stack.

Vv



"System Design” Stack Cards



- HyperVentilate Users Manual -

nee

Appendix F: "Compound List Update" stack cards.

¥





- HyperVentilate Users Manual -

Step 6: Location: Card AP8 of the "Air Permeability Test" stack.
Action: Read the text, click the "clear" buttons to clear any entries from
columns, then enter the following data:

r=53 ft _ r= 32.4 ft
Time Gauge Vacuum Time Gauge Vacuum
[min] [in H20} [min] fin H20]
9 0.1 4 1.2
11 . 0.2. 7 3.0
15 0.2 9 4.3
23 0.4 12 5.5
30 0.7 . 16 6.9
40 : 1.3 24 9.9
100 2.8 30 11
39 13
52 16
71 20
99 21
110 23
121 24.5
141 25.5
flowrate = 15 SCFM
screened interval thickness = 6.6 ft

While entering the data it is convenient to place the curser in the time
column, type in the time value, then use the "tab" key to advance to
the vacuum reading column. Enter the corresponding vacuum
value, then hit the "tab key again. As you see, this advances the
curser to the time column again. Now click the “-->Calculate<--"
button.

Result: | Your results should match those displayed in Figure 22. Soil
permeability values have been calculated by fitting the field data to
the theoretical model described in cards APS - AP7 of the “Air
Permeability Test" stack. ,

Step7: Location: Card AP8 of the "Air Permeability Test" stack.

Action: Review the results, then click on the “Explanation & Statistics"
button.. This advances you to card AP9 of the "Air Permeability
Test" stack, which lists correlation coefficients for the data fitting
process. These values give an indication of how weil the model
describes the behavior observed in the field. Values approaching
unity indicate a good fit. Your results should match those given in
Figure 23,



This equation is derived from the simplistic steady-
state radial flow solution for compressible flow (Johnson
et al. 1988), but should provide reasonable estimates
for vapor flow rates. If k can be measured or estimated,
then the only unknown parameter is the empirical “ra-
dius of influence” R,. Values ranging from 9m (30 ft)
to 30m (100 ft) are reported in the literature (Hutzler
et al. 1988) for a variety of soil conditions, but fortun-
ately Equation 5 is not sensitive to large changes in Rj.
For estimation purposes, therefore, a value of Rj=12m
(40 ft) can be used without a significant loss of accuracy.
Typical vacuum well pressures range from 0.95 ~ 0.90
atm (20 — 40 in H,O vacuum). Figure 5 presents pre-
dicted flow rates per unit well screen thickness Q/H,
expressed in “standard” volumetric units Q*/H (= Q/
H(P,/P atm) for a 5.1em radius (4-in diameter) extrac-
tion well, and a wide range of soil permeabilities and
applied vacuums. Here H denotes the thickness of the
screened interval, which is often chosen to be equal to
the thickness of the zone of soil contamination (this
minimizes removing and treating any excess “clean”
air). For other conditions the Q*/H values in Figure 5
can be multiplied by the following factors:

R, =5.lcem (2 in) R,=7.6m (25 ft) - multiply Q*/H

by 1.09
Ry, =5.1cm (2 in) Ry, = 23m (75 ft) - multiply Q*/H

by 0.90

R, = 7.6cm (3 in) R, = 12m (40 ft) - multiply Q*/H
by 1.08

R, = 10cm (4 in) R)=12m (40 ft) - multiply Q*/H
by 1.15

R,, = 10cm (4 in) Ry; =7.6m (25 ft) - multiply Q*/H
by 1.27

As indicated by the preceding multipliers given,
changing the radius of influence from 12m (40 ft) to
23 m (75 ft) only decreases the predicted flow rate by
10 percent. The largest uncertainty in flow rate calcula-
tions will be due to the air permeability value k, which
can vary by one to three orders of magnitude across a
site and can realistically only be estimated from boring
log data within an order of magnitude. It is prudent,
therefore, to choose a range of k values during this
phase of the decision process. For example, if boring
logs indicate fine sandy soils are present, then flow rates
should be calculated for k values in the range of
0.1<k<1.0 darcy.

Will the Contaminant Concentrations and Realistic
Vapor Flow Rates Produce Acceptable Removal
Rates? . .

Again, estimated removal rates R... must be com-
pared with an acceptable rate Racceptabie. aS determined
from Equation 4. Maximum removal rates are achieved
when the induced vapor flow travels only through the
zone of soil contamination and no mass-transfer limita-
tions are encountered: In other words, all vapor flows
through contaminated soils and becomes saturated with
contaminant vapors. For this “best” case the estimated
removal rate is given by Equation 2:

R= S.temi2)
Ryo 12m (40)
10, LL 310
P= 040m = 203 HO,
1] P,=0.60am = 13.68H,0 u
Vapor
3, is Flowrate
(m"/m-min)
(scf/ft)
a bt
0.80 ayn = 68h HO
a 90am = 34840 | oar
2095 am = 1.7 8 HO
or F 0011
clayey fine medium come
oo {dts sands nds ooo
ry J 1 1. 1001000,
Soit Permeabilty (darcy)

{ft H01 denote vacuums expressed as equivalent water column heights
Figure 5. Predicted steady-state flow rates (per unit well
screen thickness) for a range of soil permeabilities and applied
vacuums (P..).

a io

Figure 6. Scenarios for removal rate estimates.

Res = Cen Q : Q)

Changes in C.., are still being neglected with time
due to composition changes. Other less optimal condi-
tions are often encountered in practice and it is useful
to be able to quantify how much lower the removal rate
will be from the value predicted by Equation 2. We will
consider the three cases illustrated in Figures 6a, b. and c.

~~



- HyperVentilate Users Manual -

Table of Contents

Title : _ _ Page

Foreword
I Introduction
IL _ Definition of Some Terms Appearing in this Manual
mm Software/Hardware Requirements
IV Loading HyperVentilate Software
Vv Using HyperVentilate _
V1 - Starting HyperVentilate.,
V.2 - General Features of Cards
V3 - Sample Problem-Exercise :
V.3.1 - Navigating Through HyperVentilate .
V.3.2 -Is Venting Appropriate?
V3.3 | - Field Permeability Test
V.3.4 - System Design *”
VI References

DBonunnpPPNE Ln.

>

i

ww
RARBE

A Soil Venting Stack Cards”

B Soil Venting Help Stack Cards |

Cc Air Permeability Test Cards

D Aquifer Characterization Cards

E “System Design Cards

F Compound List Update Cards

G A Practical Approach to the Design, Operation, a and Monitoring of In Situ

Soil Venting Systems”



- HyperVentilate Users Manual -

Foreword

HyperVentilate is a software guidance system for vapor extraction (soil venting)
applications. Initial development of this program occured under the Apple Macintosh
HyperCard environment, due to its programming simplicity, ability to incorporate text and
graphics, and interfacing with other Macintosh programs (such as FORTRAN codes, etc.).
The objective was to create a user-friendly software package that could be both educational
for the novice environmental professional, and functional for more experienced users.

HyperVentilate will nor completely design your vapor extraction system, tell you exactly

how many days it should be operated, or predict the future. It will guide you through a .
structured thought process to: (a) identify and characterize required site-specific data, (b) \
decide if soil venting is appropriate at your site, (c) evaluate air permeability test results, (d)

calculate the minimum number of vapor extraction wells, and (e) quantify how results at

your site might differ from the ideal case.

HyperVentilate is based on the article "A Practical Approach to the Design, Operation,
and Monitoring of Soil Venting Systems" by P. C. Johnson, C. C. Stanley, M. W.
Kemblowski, J. D. Colthart, and D. L. Byers [Ground Water Monitoring Review, Spring
1990, p.159 - 178]. The software performs all necessary calculations and contains “help
cards" that define the equations used, perform unit conversions, and provide
supplementary information on related topics. In addition, a 62-compound user-updatable
library (to a maximum of 400 compounds) is also included.

HyperVentilate version 1.01 for the Apple Macintosh requires an Apple Macintosh
(Plus, SE, SE/30, II, IEX, or portable) computer equipped with at least 1 MB RAM (2 MB
. preferred) and the Apple HyperCard Software Program (v.2.0 or greater)

This manual is not intended to be a primer on soil venting (although the software is) and it
is assumed that the user is familiar with the use of an Apple Macintosh personal computer.



- HyperVentilate Users Manual -

Using your newly developed navigational skills and the right pointing arrow located at the
bottom of each card, slowly step your way through the stack until you reach card 7 of the
“Soil Venting Stack" stack (Figure 11). Take your time to read the text and "Help" cards
associated with each card along the, way.

Step 1:- Location: Card 7 of the “Soil Venting Stack" stack.
Action: Read this card. It explains the process that you will use to decide if
’ venting is appropriate. Then advance to card 8 of the “Soil Venting
Stack" stack. ”
Result: You are now at card 8 of the "Soil il Venting Help Stack" stack

(Figure 12).

Step 2: Location: Card 8 of the "Soil Venting Help Stack" stack.
Action: Read the instructions on this card. Take the time to read the
’ information on the two "Help" cards: "Info about Calculation” and
“About Soils (& Unit Conversions)”.

Now we will evaluate the efficacy of applying in situ soil venting to
the lower soil zone (45 - 50 ft below ground surface) in Figure 10,
which is composed of fine to medium sands. It also is the zone of
highest hydrocarbon residual levels (>20000 mg/kg TPH in some
areas),

Is Venting Appropriate?
Read This

At this point ve will proceed through a
simple thought process to decide if soil
venting is a feasible alternative. As .
‘mentioned earlier, the three main factors that
govern the success of a venting operation are:

- vapor flowrate

- vapor concentrations

~ subsurface stratigraphy (or the location of
contaminants relative to the vapor
flowpath) ©

Figure 11. Card 7 of the "Soil Venting Stack" stack.

324-235 0 - 92 - 2 QL 3



- HyperVentilate Users Manual -

Figure 1. Schematic of a typical vapor extraction operation.



Ground Surface,

1/8" OD Tefion Tubing.

Figure 14. Vadose zone monitoring well instaltation.

shows the construction of a permanent monitoring
installation that can be used for vapor sampling and
subsurface temperature measurements. Another
alternative for shallow contamination zones is the use
of. soil-gas survey probes. Data from soil-gas probes
are valuable for two reasons: (1) by comparing extrac-
tion well concentrations with soil-gas concentrations
it is possible to estimate the fraction of vapor that is
‘flowing through the contaminated zone =Cextraction
wei/Csoit gas, and (2) it is possibte to determine if the
zone of contamination is shrinking toward the extrac-
tion well, as it should with time. Three measuring
points are probably sufficient if one is located near
the extraction well, one is placed near the original
edge of the zone of contamination, and the third is
placed somewhere in between.
"These monitoring installations can also be useful for
monitoring subsurface vapors after venting has ceased.

Determining When to Turn Off the System

Target soil cleanup levels are often set on a site-by-
site basis, and are based on the estimated potential
impact that any residual may have on air quality, ground
water quality, or other health standards. They may also
be related to safety considerations (explosive limits).
Generally, confirmation soil borings, and sometimes
soil-vapor surveys are required before closure is
granted. Because these analyses can be expensive and
often disrupt the normal business of a site, it would be
valuable to be able to. determine when confirmation
borings should be taken. If the monitoring is done as
suggested previously, then the. following criteria can be
used:
© Cumulative amount removed: Determined by inte-

grating the measured removal rates (flow rate x con-

centration) with time. While this.value indicates how

much contaminant has been removed, it is usually

-not very useful for determining when to take confir-

mation borings unless the original spill mass is known

_. accurately. In most,cases that information is not avail-

able and cannot be calculated accurately from soil-
boring data.

© Extraction well vapor concentrations: The vapor con-

TM. Box Containing Vapor Sampling
Ponts &Thermocouples

centrations are good indications of how effectively
the venting system is working, but decreases in vapor
extraction well concentrations are not strong evidence
that soil concentrations have decreased: Decreases
may also be due to other phenomena such as water
table level increases, increased mass transfer resist-
ance due to drying, or leaks in the extraction system.
@ Extraction well vapor composition: When combined
with vapor concentrations these data offer more
insight into the effectiveness of the system. If the total
vapor concentration decreases without a change in
composition, it is probably due to one of the phe-
nomena mentioned previously, and is not an indica-
tion that the residual contamination has been signific-
antly reduced. If a decrease in vapor concentration
is accompanied by a shift in composition toward less
volatile compounds, on the other hand, it is most
_ likely due to a change in the residual contaminant
concentration. For residual. gasoline cleanup, for
example, one might operate a venting system until
benzene, toluene, and xylenes were not detected in
the vapors. The remaining residual would then be
composed of larger molecules, and it can be argued
that these do not pose a health threat through volatili-
zation or leaching pathways.
© Soil-gas contaminant concentration and composition:
These data are the most useful because it yields infor-
mation about the residual composition and extent of
contamination. Vapor concentrations cannot, in gen-
eral, be used to determine the residual level, except
in the limit of low residual levels (note that Equation 1
is independent of residual concentration). It is important
to consider the effect of continued soil-venting system
operation on soil-gas sampling results. Results taken
during operation, or immediately after shutdown, can
be used to assess the spatial extent of contamination
and composition of the vapors. After the system is
shut down, vapors will begin to migrate away from
the source and equilibrate on a larger scale. True soil-
vapor concentrations can be measured once equilib-
rium concentrations are attained in the sampling
zone; at least two sampling times will be required to
determine that equilibration has occurred. Due to the
diffusion of vapors, samples taken after shutdown are
not good indicators of the spatial e extent of the conta-
minated zone. -

Other Factors
Increased Biodegradation

It is often postulated that because the air supply to
the vadose zone is increased, the natural aerobic micro-
biological activity is increased during venting. While the
argument is plausible and some. laboratory. data are
available (Salanitro et al. 1989), conclusive evidence
supporting this theory has yet to be presented. This is
due in part to the difficulty in making such a mea-
surement. A mass balance approach is not likely to be
useful because’ the initial spill mass is generally not
known with sufficient accuracy. An indirect method
would be to measure CO, levels in the extraction well



changes in composition and liquid-phase diffusion affect
the behavior. Currently there are no simple analytical
solutions for these situations, but it can be postulated
that they should be less than the rates predicted previ-
ously for pure components.

The use of equilibrium-based models 1b predict
required removal rates will be discussed under the next
question.

What Residual, If Any, Will Be Left in the Soil?
What Vapor Composition and Concentration
Changes Will Occur With Time? How Do These
Values Relate to the Regulatory Requirements?

As contaminants are removed during venting. the
residual soil contamination level decreases and mixture
compositions become richer in the less volatile com-
pounds. Both of these processes result in decreased
vapor concentrations, and hence, decreased removal
rates with time. At low residual soil contamination levels
(<500.ppm) Equation 1 becomes less valid as sorption
and dissolution phenomena begin to affect the soil resid-
ual — vapor equilibrium. In the limit of low residual
contamination levels, contaminant equilibrium vapor
concentrations are expected to become proportional to
the residual soil contaminant concentrations. As venting
continues and residual soil levels decrease, therefore, it
becomes more difficult to remove the residual contami-
nation. It is important to realize that, even with soil
venting, there are practical limitations on the final soil
contamination levels that can be achieved. Knowledge
of these limits is necessary to realistically set cleanup
criteria and design effective venting systems.

The maximum efficiency of a venting operation is
limited by the equilibrium partitioning of contaminants
between the soil matrix and vapor phases. The maxi-
mum removal rate is achieved when the vapor being
removed from an extraction well is in equilibrium with
the contaminated soil. Models for predicting this maxi-
mum removal rate have been presented by Marley and
Hoag (1984) and Johnson et al. (1988). The former con-
sidered only compositions in a residual free-phase, while
the fatter also considered the effects of sorption and
dissolution processes. A complete discussion of the
development of these models is not appropriate here,
but we will discuss the use of the predictions.

The change in composition, vapor concentration,
removal rate, and residual soil contamination level with
time are functions of the initial residual composition,
vapor extraction well flow rate, and initial soi} contami-
nation level. It is not necessary to generate predictions
for every combination of variables, however, because
with appropriate scaling all results will form a single
curve for a given initial mixture composition. Figure 8a
presents the results computed with the model presented
by Johnson et al. (1988) for the “weathered” gasoline
mixture whose composition is given by Table 2. The
important variable that determines residual soil levels,
vapor concentrations, and removal rates is the ratio QU
M(t=0), which represents the volume of air drawn
through the contaminated zone per unit mass of conta-

benzene (20°C' ”
zene ye ” “
Ry =5.lem py Zone
R = 900 em ickness
kgid 5
eid) (cm)
100
10.
) 0
0 10-200 00 400500

Time (d)
Figure 7. Estimated maximum removal rates for a venting

operation limited by diffusion.
a) , 100
Weathered Gasoline
Tac
a 10% moisture content | 80.
frm a-prucw — Clt=0) = 222: % removed
QCIQCIt=0) ooeaien se wt
or {
40,
00
»
Full Composition
0001 0
o 100 200 300
Qumm(t=0) {l/g)
b) 1 - 100
Weathered Gasoline
Texte
a 10% moisture content | ®
% removed
‘changed trom 4gtusewe — C(t=0) = 270 maf
QCRCI=0) 3 phue sem | wo
. 1
40
OL
2
Approximate Composition
0001 ‘0
oO 100 300
Qum(=0) ue

Figure & Maximum predicted removal rates for a weathered .
gasoline: (a) full composition (b) approximate composition.

minant. In Figure 8, the scaled removal rate (or equiva-
lently the vapor concentration) decreases with time as
the mixture becomes richer in the less volatile com-
pounds.

While a detailed compositional analysis was availa-
ble for this gasoline sample. an approximate composi-
tion based on a boiling point distribution curve predicts
similar results. Figure 8b presents the results for the
approximate mixture composition also given in Table 2.

Model predictions. such as those shown in Figure 8
for the gasoline sample defined by Table 2, can be used
to estimate removal rates (if the vapor flow rate is speci-
fied), or alternatively the predictions can be used to
estimate vapor flow rate requirements (if the desired
removal rate is specified). For example, if we wanted
to reduce the initial contamination level by 90 percent.



Pressure Vapor Flowmeter

Vapor Tet
Gauge pr Treat

E

Vapor

W4

Pressure Sampling Probes “=

i
Hts

Figure 10. Air-permeability test system,

driven soil- -vapor sampling probes (for <20 ft deep con-
tamination problems) or more permanent installations.
Flow rate and transient pressure distribution data
are used to estimate the soil permeability to vapor flow.
The expected change in the subsurface pressure distribu-
tion with time P'(r,t) is predicted (Johnson et al.) by:

-_2_
~ 4nm(k/u)

rep
4kPaim t (3)

For (r W/4KP aimt)<0.1° Equation’ 13 can be approxi-
mated *

rep
"= ———— |}-0.5772 - |
Pre 5 2-tn( Ee

) + me (4)
am Atm

= “gaugeTM pressure measured at distance r
and time t .
= stratum thickness _
adial distance from vapor extraction well
soil permeability to air flow
iscosity of air = 1.8 x 10+ g/cm-s
ir-filled soil void fraction
ime
= volumetric vapor flow rate from extraction
well
Patm = ambient atmospheric pressure = 1.0 atm =
1.013 x 10° g/cm-s*. -
Equation 14 predicts a plot of p'-vs- In(t) should: be a
straight line with slope A and y-intercept B equal to:

-_2_
© 4am(kip)

r eu

= ——— |-0.5772 - In 15:
4nm(k/y) (arc I 08)
The permeability to vapor flow can then be calculated
from the data by one of two methods. The first is applica-

ble when Q and m are known. The calculated slope A

is used:

ke
~ 4Anm (16)

The second approach must be used whenever Q or m
is not known. In this case the values A and B are both
used:

> ep

k= 7
4Paun

oe + 05772) _ 7)

Equation 13 can also be.used to choose the locations
of subsurface pressure monitoring points before con--
ducting the air permeability test, given an estimation of
k and the flow rate to be used.

Vapor samples should be taken at the beginning and
end of the air permeability test, which should be con-
ducted for a long enough ‘time to extract at least one
“pore volume” Vp of vapor from the contaminated soil
zone. This ensurés that all vapors existing in the forma-
tion prior to venting are removed. The vapor concentra-
tion-at the start of the test is representative. of the equi-
librium vapor concentration, while the concentration
measured after one pore volume has been extracted
gives, an indication of realistic removal rates and the
mixing or diffusional limitations discussed in association
with Figure 6. The time 7p for one pore volume to be
removed is:

= VplQ = €4 TR? H/Q . 18)"

where R, H. €,. and Q are the radius of the zone of
contamination, vertical thickness of the zone of contami-
nation, air-filled void fraction, and volumetric vapor
flow rate from the extraction well. For example, consider
the case where R=12 m, H=3 m. €,4=0.35, and Q=0.57
m? /min (20 ft' min). Then tp=475 m ‘/0.57 m* /min=833
min=14 h. .

Ground Water Pumping Tests

To achieve efficient venting, the hydrocarbon-con-
taminated soil has to.be exposed to air flow, which in
turn.requires that the water table be lowered to counter-
act the water upwelling effect caused by the decreased
vapor pressure in the vicinity of a venting well (Johnson
et al. 1988) and to possibly expose contaminated soil
below the water table. Thus the ground water pumping
system has to have a sufficient pumping rate and be
operated for along enough time period to obtain the.
required drawdowns. Because most venting systems are
installed above phreatic aquifers, two aquifer parame-
ters are needed for the design: average transmissivity T’
and storage coefficient S. These parameters can be esti-
mated using the results of the standard transient ground
water pumping test with a constant pumping rate (Bear
1979). Using the estimated values. the required pumping’
rate may be calculated as follows:

Q = 4aT S(r,ty/W(u) . (19)

where: W(u) is the well function (Bear 1979) of u T°}



- HyperVentilate Users Manual -

Model Predictions

igen
To the right is a summery of the Goll Penmeal (in) Range (
data you have input. If youwishw| Radius of (a
[change any of the info, then click Pome Boy thickness (ff)
on the parameter name, and redo
the calculations on the card you will
‘be taken to. Press the blinking

i”)

to i
fol LLL
to

(Boiling Point Range #4 144
Boiling Point Range #5 250

@ (Senerate Predictions ] (Senerate Predictions } Predictions

eG»

Figure 17. Card 16 of the "Soil Venting Stack" stack.

®D C_-> Import Data<-- Saturated Vapor 0 Img)

FIRST PRESS THE IMPORT Min Volume to Remove (L-aite-
DATA BUTTON! >90% of Initial Residual residual]

These are the results for the Temperature ("C): 18
hat : | Weathered Gasoline

BP a3 BP 84 BP és
Residual | Residual | Residual
[Swul] | [Swvelj
24.010 | 22.140
23.982 | 23.000
23.474 23.820
22.403
20.771

18.503

15.556

Figure 18. Card 17 of the "Soil Venting Stack” stack.
Vv



United States Solid Waste And EPA 500-C-B-92-001
Environmental Protection Emergency Response March 1992
Agency * {OS-420) WF. G

HyperVentilate Users Manual

A Software Guidance System
Created For Vapor Extraction
Applications

Ground Surface oO yt

Printed on Recycled Paper



4Tt, and s(r,t) is the required drawdown at distance r
and pumping time equal to t.

System Design

In this section the questions that must be answered
in order to design an in situ soil-venting system will be
discussed. It is not the authors’ intention to provide a
generic “recipe” for soil-venting system design; instead,
a structured thought process to guide in choosing the
number of extraction wells, well spacing, well construc-
tion, etc. is suggested. Even in a structured thought
process, intuition, and experience play important roles.
There is no substitute for a good fundamental under-
standing of vapor flow processes, transport phenomena,
and ground water flow.

Choosing the Number of Vapor Extraction Wells

Three methods for choosing the number of vapor
extraction wells are outlined in the following text. The
greatest number of wells from these three methods is
then the value that should be used. The objective is to
satisfy removal rate requirements and achieve vapor
removal from the entire zone of contamination.

For the first estimate residual contaminant composi-
tion and vapor concentration changes with time are neg-
lected. The acceptable removal rate Racceptable iS calcu-
lated from Equation 4, while the estimated removal rate
from a single well R,, is estimated from a choice of
Equations 2, 6, 7, or 12 depending on whether the speci-
fic site conditions are most like Figure 6a, 6b, or 6c.
The number of wells Nycu; required to achieve the
acceptable removal rate is:

Nwens = Racceptable/Rest (20)

Equations 2,6, and 7 require vapor flow estimates, which
can be calculated from Equation 5 using the measured
soil permeability and chosen extraction well vacuum P,,.
At this point one must determine what blowers and
‘vacuum pumps ate available because the characteristics
of these units will limit the range of feasible (P,Q)
values. For example, a blower that can pump 100 scfm
at 2 in. H,O vacuum may only be able to pump 10 scfm
at 100 in. HO vacuum.

The second method, which accounts for composition
changes with time, utilizes model predictions, such as
those illustrated in Figure 8. Recall that equilibrium-
based models are used to calculate the minimum vapor
flow to achieve a given degree of remediation. For exam-
ple, if we wish to obtain a 90 percent reduction in resid-
ual gasoline levels, Figure 8 indicates that ~ 100 1-vapor/
g-gasoline must pass through the contaminated soil
zone. If our spill mass is 1500kg (=500 gal), then a mini-
mum of 1.5 x 10* l-vapor must pass through the conta-
minated soil zone. If the target cleanup period is six
months, this corresponds to a minimum average vapor
flow rate of 0.57 m? /min (=20 cfm). The minimum num-
ber of extraction wells is then equal to the required
Minimum average flow rate/flow rate-per-well.

The third method for determining the number of

wells ensures that vapors and residual soi] contamina-
tion are removed from the entire zone of contamination
Nmin- This is simply equal to the ratio of the area of
contamination Acontamination tO the area of influence of
a single venting well #R/:

Acontamination

Non =
min aR?

21)

This requires an estimate of Rj, which defines the zone
in which vapor flow is induced. In general, Ry depends
on soil properties of the vented zone, properties of sur-
rounding soil layers, the. depth at which the well is
screened, and the presence of any impermeable bound-
aries (water table, clay layers, surface seal, building
basement. etc.). At this point it is useful to have some
understanding of vapor flow patterns because, except
for certain ideal cases (Wilson et al. 1988), one cannot
accurately predict vapor flow paths without numerically
solving vapor-flow equations. An estimate for R; can
be obtained by fitting radial pressure distribution data
from the air permeability test to the steady-state radial
pressure distribution equation (Johnson et al. 1988):

2
P(t) = Py [1+ (1 - (782) ayn (2)
w 1.

where P(r), Patm, Py, and R,, are the absolute pressure
measured at a distance r from the venting well, absolute
ambient pressure, absolute pressure applied at the vapor
extraction well, and extraction well radius, respectively.
Given that these tests are usually conducted for less
than a day, the results will generally underestimate Rj.
If no site-specific data are available, one can conserva-
tively estimate R, based on the published reports from
in situ soil-venting operations. Reported R, values for.
permeable soils (sandy soils) at depths greater than
20 feet below ground surface, or shallower soils beneath
good surface seals, are usually 10m - 40m (Hutzler et
al. 1988). For less permeable soils (silts, clays), or more
shallow zones R, is usually less.

Choosing Well Location, Spacing, Passive Wells, and
Surface Seals

To be able to successfully locate extraction wells,
passive wells, and surface seals one must have a good
understanding of vapor flow behavior. Weill locations
should be chosen to ensure adequate vapor flow through
the contaminated zone, while minimizing vapor flow
through other zones.

If one well is sufficient, it should almost always be
placed in the geometric center of the contaminated soil
zone, unless it is expected that vapor flow channeling
along a preferred direction will occur. In that case the
well should be placed so as to maximize air flow through
the contaminated zone.

When multiple wells are used it is important to con-
sider the effect that each well has on the vapor flow to
all other wells. For-example, if three extraction wells
are required at a given site, and they are installed in
the triplate design shown in Figure 11a, this would result

—



“Soit Venting Stack” Cards

System Design... System Mouttoring...



- HyperVentilate Users Manual -

resem
A Practical Approach to the
* Design, Operation, and
Monitoring of In-Situ Soil
Venting Systems

version 1.01
1991 AN Rights Reserved
Shall Ol Company

@Q

a HyperCord tack Created dy:
Paul C. Johnson, Ph.D.
Any J, Stadenau
Shell Development
‘Westhollow Research Center

\ 7

~ Buttons

Figure 2. First Card of the "Soil Venting Stack" stack.

Ons
Buttons have been placed in each
card. Clicking on any button will
perform an action, such as:

Go Home 1 first
card in Venting Stuck

Go to nextcard

Go t Help cord

Print card or
text field

Performa Calculation

When curious, click on Symbols,
Pictures or Text.

Figure 3. Card H1 of the "Soil Venting Help Stack" stack.

Fields
Fields may contain information, or they may be
aplace for you to input numbers.

Scrolling Field:

Click on arrows t move
‘ext up or down:

Boxed Data Field:

‘When you see an I-beam
cursor appear in a boxed
field, click the mouse in the
box to set the cursor. Then
you may enter dats.

A button vill then usually
‘be pushed perform en
ection or calculation.

Click on the arrows, or
‘move the box up or down
‘with the mouse.

In this area, you cen

Try this example:

Enter Number in Box

(1 inches
2.54 centimeters



- HyperVentilate Users Manual -

V. Using HyperVentilate

The authors of HyperVentilate intend it to be an application that requires little pre-
training for the user. It is mouse-driven and instructions are included on each card, so
please take the time to read them when you first use HyperVentilate.

This section of the users manual is divided into three subsections. Start-up instructions are
given in the first, basic features of the cards are described in the second, and a sample
exercise is presented in the third. For reference, copies of all cards, as well as more details
on each are given in Appendices A through F. :

V.1. Starting HyperVentilate -

1)

2)

3)

4)

Those users with color monitors should-use the "Control Panel" (pull down the
"é menu and select "Control Panel", then click on'the "Monitors" icon) tc to set their
monitors to black and white, and two Shades of grey.

To avoid unnecessary veard- -flipping” > set the "Text Arrows" option in your
"Home" stack "User Preferences" card to on. You can get to this card from within
any HyperCard application by selecting "Home" under the "Go" menu. This will
take you to the first card in the “Home” stack. At this point click on the left-
pointing arrow and the "User Preferences" card will appear on your screen. Then
click on the square to the left of "Text Arrows" until an “X" appears in the square.

HyperVentilate is started by double-clicking on the "Soil Venting Stack" file icon

* from the Finder (or Desktop), or by choosing "Open" under the "File" menu (Note

that using a more advanced version of HyperCard than the one under which this
system was developed (v 2.0) may require you to first “convert” each of the seven
HyperCard stacks contained in HyperVentilate). :

Your monitor should display the card shown in Figure 2. Note that there are a
number of buttons on this card; there are two at the lower left corner, and then each
file folder tab is also a button (some cards may contain less obvious "hidden"
buttons; try clicking on the authors name on the title card for example). Clicking on
any of these will take you to another card. For example, clicking on the "About
This Stack" button will take you to the card shown in Figure 3, which gives a brief
description about the use of buttons and-fields. Read this card well.

Explore for a few minutes. Try to see where various buttons will take you, try
entering numbers in fields, or play | with calculations: Again, just remember to read
instructions given on the cards.



- HyperVentilate Users Manual -

Appendix D: "Aquifer Characterization" stack cards.





TABLE 2
Composition (Mass Fractions) of Fresh and Weathered Gasolines

Compound M, Fresh . Weathered * Approximate
Name . (p) Gasoline Gasoline * Composition
propane | 44.1 0.0001 0.0000 0. °
isobutane 58.1 0.0122 0.0000 0
n-butane 58.1 0.0629 0.0000 tt)
trans-2-butene 56.1 0.0007 0.0000 0
cis-2-butene 56.1 0.0000 . 0.0000 0
3-methyl-I-butene 1.1 0.0006 . 0.0000 0
isopentane 72.2 0.1049 0.0069 0.0177
I-pentene . 70.1 0.0000 0.0005 0
2-methyl-I-butene 70.1 0.0000 0.0008 0
2-methyl-1,3-butadiene 68.1 0.0000 0.0000 0
n-pentane . 722 0.0586 0.0095 0
trans-2-pentene 70.1 0.0000 * 0.0017 0
2-methyl-2-butene 70.1 0.0044 0.0021 0
2-methyl-1,2-butadiene 68.1 0.0000 0.0010 0

. 3,3-dimethyl-1-butene 84.2 0.0049 0.0000 0

a cyclopentane . 70.1 0.0000 0.0046 0.0738
3-methyl-1-pentene $4.2 0.0000 . 0.0000 0
2.3-dimethylbutane 86.2 0.0730 . 0.0044 0
2-methylpentane 86.2 0.0273 . 0.0207 tt)
3-methylpentane 86.2 0.0000 0.0186 0.
n-hexane 86.2 0.0283 0.0207 0
methyicyclopentane 84.2 0.0083 0.0234 0
2.2-dimethylpentane 100.2 0.0076 0.0064 0
benzene 78.1 : 0.0076 0.0021 0

. cyclohexane 84.2 0.0000 0.0137 0.1764
i 2,3-dimethylpentane 100.2 0.0390 0.0000 0

3-methylhexane 100.2 0.0000 , 0.0355 0
3-ethylpentane 100.2 0.0000 0.0000 0
n-heptane 100.2 0.0063 0.0447 0
2,2.4-trimethylpentane 114.2 0.0121 . 0.0503 0
methylcyclohexane 98.2 0.0000 0.0393 0
2,2-dimethylhexane 114.2 0.0055 0.0207 0
toluene. 92.1 0.0550 0.0359 0.1926
2,3,4-trimethyipentane - 114.2 0.0121 0.0000 0
3-methylheptane 114.2 0.0000 . 0.0343 tt)
2-methylheptane 114.2 0.0155 0.0324 0
n-octane 4.2 0.0013 0.3000 0
2,4,4-trimethylhexane 128.3 0.0087 0.0034 0
2,2-dimethylheptane 128.3 0.0000 0.0226 0
ethylbenzene 106.2 0.0000 0.0130 0
p-xylene 106.2 0.0957 0.0151 0
m-xylene , 106.2 0.0000 0.0376 0.1641
3,3,4-trimethylhexane . 128.3 0.0281 0.0056 0
o-xylene . 106.2 0.0000 0.0274 0
2,2,4-trimethylheptane : . 142.3 + 0.0105 0.0012 0
n-noname 128.3 0.0000 0.0382 Q-
3,3,5-trimethylheptane 142.3 0.0000 0.0000 0
n-propylbenzene 120.2 0.0841 0.0117 0.1455
2,3,4-trimethylheptane 142.3 0.0000 0.0000 0
1,3,5-trimethytbenzene 120.2 0.0411 0.0493 0
1,2-4-trimethyibenzene 120.2 0.0213 0.0707 .0
n-decane 142.3 0.0000 0.0140 0
methylpropylbenzene . 134.2 0.0351 0.0170 0
dimethylethylbenzene 134.2° 0 | 0.0307 - 0.0289 0.0534
n-undecane 156.3 0.0000 0.0075 0
1,2,4,5-tetramethylbenzene 134.2 0.0133 0.0056 0
1,2,3,4-tetramethylbenzene 134.2 0.0129. 0.0704 0.1411
1.2,4-trimethyl-S-ethylbenzene 148.2 0.0405 0.0651 0
n-dodecane 1703 0.0230 0.0000 0
napthalene Tee 128.2 0.0045 0.0076 0
n-hexylbenzene . 162.3 0.0000 0.0147 0.0357
methyinapthalene 142.2 0.0023 0.0134 0
Total 1.0000 1.0000 1.00000



- HyperVentilate Users Manual -

System Design

Figure 24. Card 22 of the "Soil Venting Stack" stack.

V.3.4 Sample Problem Exercise - System Design

In this example we illustrate the use of HyperVentilate for system design guidance. As in
§V.3.2 and §V.3.3, we use the sample site presented in Figure 10. At this site gasoline
was detected in three distinct soil strata: a fine to coarse zone located 10 - 30 ft below
ground surface (BGS), a silty clay/clayey silt zone located 30 to 42 ft BGS, and a fine to
medium sand zone that extends from 42 ft BGS to the deepest soil boring (60 ft BGS).
Groundwater is detected in monitoring wells at about 50 ft BGS.

Advance to card 22 of the "Soil Venting Stack” stack to begin (Figure 24).

Step 1: Location: Card 22 of the "Soil Venting Stack" stack.
Action: Use the right-pointing arrow to advance to card 23 of the "Soil
Venting Stack" stack. Read the text, then advance to card 24 of the
"Soil Venting Stack" stack.
Result: Card 24 of the "Soil Venting Stack” stack, which appears in Figure
25, should be displayed.

Step 2: Location: Card 24 of the "Soil Venting Stack” stack.
Action: Read the text, explore using some of the options. You will find that
the options: "Well Location", "Well Construction", “Surface Seals",
"Groundwater Pumping System", and "Vapor Treatment" provide
some useful guidance information on aspects and components of a
soil venting system. Return to card 24.
Result: Card 24 of the "Soil Venting Stack" stack should be displayed.



- HyperVentilate Users Manual -

Appendix B: "Soil Venting Help Stack" stack cards.



- HyperVentilate Users Manual -

Air Permeability Test - Data Analysis (cont.)

r= (32.4 ]ito r )
(min) (i H20) (min) (in H20)

potetesees

derey(A) k= [2.658452] dercy(A) ke :
9.298663 dercy(B) k= [7.767599] dercy(B) k= darcy (B)

+ EXD sr Fo

Figure 22. Card AP8 of the "Air Permeability Test” stack.

Air Permeability Test - Data Analysis (cont.)

On the previous Card (APS), the data you input were fit to the epproximat expression given on Card
APG. It-was analyzed using both methods described on cant AP?, if you input values for the

J extrction well flowrate (Q) and the stratum thickness (mm), Below each column of dat, the two
cslulated permeability values are denoted by:

darcy(A) - refers tb calculation method | (see Cart AP7)
| dere) - refers to calculation method 2 (see Card AP7)

Correlation Coef.
o

During the regression analyses, the deta expressed as.
[pairs of points (In((), P*) ate fit to « line. The'”

"correlation coefficient", x, is a measure of how well dota set #1. [0.941158 ]
the data conform the theoretical curve. Ag r-->1, the
em pointy all fell on the theoretical curve. At the right + date set $2

fare given the correlation coefficient values for the three .
}dat sets. For more info on the meaning of r, consult dam set #3
ony introductory Statistics book. .

0.98602

Figure 23. Card AP9 of the "Air Permeability Test" stack,

Vv



"System Design" Stack Cards

Help: Minimum Number of Wells

Help: Well Parameters

im general wit be th rating of tho well

{a te length of the sted interval of tho i
‘well orth thickncas of the pormesble
‘zane, whicbaves ip emailer. [Z

Prcanetr, and mest pared abuso in the
range 40-1202

Zeataasona

iS

‘Tee “Minimum Number of Wells” ia calcalaand by the two methods discumed below:
‘Baden Are

‘a Gis prone we oximen bs mnimom number of wells roqired
{w provide as flow through the contaminated mee as you have New = Bo
defaotit, 1 Re denotes to eatial exent of commionion, asd Ri ‘
denotes the “radine of influcnce” of am extraction weil, then:

1b) asad on Critical Volume of Vapor =|

‘an this approach wo dcummine the mnmber of wella required 19 News = Yeti
‘eurect ths critical vohume of vapor trem ths coctaminatnd soll zone Qua €AT
‘within the desired time frame. in thin appeosct:

| Veritical = critical vohame of vapor (L/g-scaidual) (© sefficiency of erection
See nan amoeog)

sometimes used to control the
vapor flow paths. Figure 12
ittnstrates the effect that « surface
seal will have on vapor flow

patterns. For shallow treatment
{zones (<S m) the surface seal will

Di wf aurface seal en



-- HyperVentilate Users Manual -

I. Introduction

In situ vapor extraction, or soil venting is recognized as an attractive remediation alternative
for “permeableTM soils contaminated with "volatile" compounds. As Figure 1 illustrates,
vapors are removed from extraction wells, thereby creating a vacuum and vapor flow
through the subsurface. Until the residual contamination is depleted, contaminants will
volatilize and be swept by the vapor flow to extraction wells. While its use has been
demonstrated at service stations, Superfund sites, and manufacturing locations (see Hutzler
et al. [1988] for case study reviews), vapor extraction systems are currently designed more
by intuition than logic. In fact, many systems are installed at sites where the technology is

not appropriate.

“A Practical Approach to the Design, Operation, and Monitoring of In Situ Soil Venting
Systems" [Johnson et al. 1990a - see Appendix G] is a first attempt at creating a logical
thought process for soil venting applications. The article, which is based on earlier results
of Thornton and Wootan [1982], Marley and Hoag [1984], Johnson et al. [1990], and
discussions with several of these authors, describes a series of calculations for determining:
(a) if soil venting is appropriate at a given site, (b) limitations of soil venting, and (c)
system design parameters, such as minimum number of extraction wells and potential
operating conditions.

HyperVentilate is a software guidance system based on the Johnson et al. [1990a]
article. The software performs all necessary calculations and contains “help cards" that
define the equations used, perform unit conversions, and provide supplementary
information on related topics. In addition, a 62-compound updatable chemical library (to a
maximum of 400 compounds) is included. ‘

Initial development of this program occured under the Apple Macintosh HyperCard
environment, due to its programming simplicity, ability to incorporate text and graphics,
and interfacing with other Macintosh programs (such as FORTRAN codes, etc.). The
objective was to create a user-friendly software package that could be both educational for
the novice environmental professional, and a functional tool for more experienced users.
The OASIS [1990] system created: at Rice University for groundwater contamination
problems is another excellent example of the use of HyperCard as a technology transfer
tool.

This document is a users manual for HyperVentilate. It contains sections describing the
installation and operation of the software. During the development of HyperVentilate,
the goal was to create a guidance system that could be used with little or no instruction.
Experienced Apple Macintosh users, therefore, can load and explore the capabilities of this
program after glancing at the "Loading HyperVentilate Software" section. Those users that
are less comfortable about exploring software without a manual are encouraged to read
through it once, and work through the sample problem. It is intentionally brief, and a
beginner should be able to navigate through the system in less than a couple hours. It is

assumed that the user has some previous Macintosh experience. If not, consult a’

Macintosh users manual for a quick tutorial.



- HyperVentilate Users Manual -

At this site the residual hydrocarbon is a "weathered" gasoline, so
choose this selection from the three composition options listed. The
"Fresh” and "Weathered" gasoline selections correspond to pre-
programmed compositions that are useful for estimation purposes. /
If you knew the composition of your residual, then you could enter
it by selecting the "Enter Distribution” option. Click on the “View
Distributions" button to take a look at the compound library and the
pre-specified composition of "weathered" gasoline. 4

Result: You are now at card H16 of the "Soil Venting Help Stack" stack
(see Figure 14).

Step 6: Location: Card H16 of the "Soil Venting Help Stack" stack.
Action: | View the library and pre-specified composition: If you are
interested, explore some of the help cards. Then click on the
“Return to Vapor Conc. Estimation Card” button to return to card 10
of the "Soil Venting Stack" stack.
Result: “You are now at card 10 of the "Soil Venting Stack” stack (Figure
13).

Step7: Location: Card 10 of the "Soil Venting Stack" stack.

Action: Click on the "Perform Calculations" button.

Result: HyperVentilate calculates the maximum possible vapor
concentration corresponding to the specified composition and
temperature. The results are displayed in Card 10 of the "Soil
Venting Stack” stack, which should now look like Figure 13.

Step 8: Location: Card 10 of the "Soil Venting Stack" stack.

Action: Using the right-pointing arrow button, advance to card 11 of the
“Soil Venting Stack" stack. Take the time to read the text, then click
on the "Calculate Estimates" button

Result: | You are at card 12 of the "Soil Venting Stack" stack. The calculated
flowrates and maximum possible removal rates are displayed along
with an updated list of the input parameters that you have entered.
Your screen should look like Figure 15, if you have chosen the
“Ib/d" units.

Step9: Location: Card 12 of the "Soil Venting Stack" stack.
Action: — Click on the right-pointing arrow button. You are now at card 13 of
the "Soil Venting Stack" stack. Read the text, then enter:
estimated spill mass = 4000 kg
desired remediation time = 180d
Now click on the "-->Press to Get Rates<--" button



then Figure 8 predicts that ~ 100 I-air/g-gasoline will
be required. This is the minimum amount of vapor
required, because it is based on an equilibrium-based
modél. The necessary minimum average vapor flow rate
is then equal to the spill mass times the minimum
required vapor flow/mass gasoline divided by the
desired duration of venting. Use of this approach is
illustrated in the service station site example provided
at the end of this paper.

Figure 8 also illustrates that there is a practical limit
to the amount of residual contaminant that can be
removed by venting alone. For example, it will take'a
minimum of 100 I-vapor/g-gasoline to remove 90 percent
of the weathered gasoline defined in Table 2. while it
will take about 200 I-air/g-gasoline to remove the
remaining 10 percent. In the case of gasoline. by the
time 90 percent of the initial residual has been removed,
the residual consists of relatively insoluble and non-
volatile compounds. It is important to recognize this
limitation of venting. and when setting realistic cleanup
target levels, they should be based on the potential envi-
ronmental impact of the residual rather than any specific
total residual hydrocarbon levels. Because mandated
cleanup levels are generally independent of the remedia-
tion method, this also indicates that soil venting will
often be one of many processes used during a given site
remediation. It is not difficult to envision that in the
future soil venting may be followed or coupled with
enhanced biodegradation to achieve lower cleanup
levels.

lt is appropriate to mention at this point that the.
mathematical models presented in this paper are being
used as “tools” to help plan and design venting system.
As with any models, they are mathematical descriptions
of processes that at best approximate real phenomena,
and care should be taken not to misapply or misinterpret
the results.

Are There Likely to Be Any Negative Effects of Soil
Venting? :

It is possible that venting will induce the migration
of off-site contaminant vapors toward the extraction
wells. This may occur at a service station. which is often
in close proximity to other service stations. If this occurs,
one could spend a lot of time and money to unknowingly
clean up someone else's problem. The solution is to
establish a “vapor barrier” at the perimeter of the con-
taminated zone. This can be accomplished by allowing
vapor flow into any perimeter ground water monitoring
wells (which often have screened intervals extending
above the saturated zone), which then act as passive air
supply wells. In other cases it may be necessary to install
passive air injection wells, or trenches, as illustrated in
Figure 9a.

As pointed out by Johnson et al. (1988), the applica-
tion of a vacuum to extraction wells can also cause a
water table rise. In many cases contaminated soils lie
just above the water table and they become water satur-
ated, as illustrated in Figure 9b, The maximum rise
occurs at, or below the. vapor extraction well, where the °
water table rise will be equal to the vacuum at that point

eS 4

Vapot Extraction
Well
Off-Site
‘Contamination
— _
— _ oe
Passive Air Injection Well
or
Perimeter Groundwater Monitoring Well
b)
Vapor Exaction
Well
Unsaturated
Soil Zone
=> _
= _
— =
Sauraed Water Table Upwelling
Soil Zone _ Caused by Vacuum

Figure 9. (a) Use of passive vapor wells to prevent migration
of off-site contaminant vapors. (b) Water table rise caused by
the applied vacuum.

expressed.as an equivalent water column height (i... in
ft H,O). The recommended solution to this problem is
to install a dewatering system, with ground water pump-
ing wells located as close to vapor extraction wells as
possible. The dewatering system must be designed to
ensure that contaminated soils remain exposed to vapor
flow. Other considerations not directly related to vent-
ing system design, such as soluble plume migration con-
trol and free-liquid product yield. will also be factors in
the design of the ground water pumping system.

Design Information

If venting is still a remediation option after answer-
ing the questions above. then more accurate information
must be collected. Specifically, the soil permeability to
vapor flow, vapor concentrations, and aquifer charac-
teristics need to be determined. These are obtained by
two field experiments: air permeability and ground
water pumping tests, described briefly next.

Air Permeability Tests

Figure 10 depicts the setup of an air permeability
test. The object of this experiment is to remove vapors
ata constant rate from an extraction well, while monitor-
ing with time the transient subsurface pressure distribu-
tion at fixed points. Effluent vapor concentrations are
also monitored. It is important that the test be condicted
properly to obtain accurate design information. The,
extraction well should be screened through the soil zone

that will be vented during the actual operation. In many.

cases existing ground water monitoring wells are suffici-

ent, if their ‘screened sections extend above the water
table. Subsurface pressure monitoring probes can be



“Air Permeability Stack" Cards

Air Permeability Tests...

is inne pay ge
'bener estimate of the soil permeability of

Pore Velome Ketimatiow

Baer

1) Soll Layer Thicenem (8

2) Bniensod Radin of Inthacocs ty

Air Permeability Test - Data Analysis

‘The expected decrease in subsurface pressure (increase in gauge vacuum) P is
‘rodicted by: (ee Joimeon et) (1990] for derivation?

=- 2 eo
ross

recy

Air Permeability Test - Data Analysis (cont.)
The permeability, k, can then be calculated by one of two mahods:

(1) The fire is applicable when both Q (flowrate) and en (well screen intereal) are
known accurately, The calculated alope A is used:

re Qh
Tasa

(‘The second approach is used whenever Q or m are not known with confidence.
In this case, bath the slope, A, and intercept, B, are used:

opts
r Frere 09772 + By

Air Permeability Test - Data Analysis (cont.)
For (12 £ pH & Pare t) < 0.1, the governing equation can be approximated by the
‘expression:

. “ig en
p92 _1 9572 dE) + it)

‘This Equation predicts that a plot of P* -vs-In(t) should be « straight line with slope
‘A and y-interoept B equal to:

Q ci ER.
aemaeray 7? Ep

cane (5)

C1



In Figure 6a a fraction $ of the vapor flows through
uncontaminated soil. The fraction can be roughly esti-
mated by assessing the location of the well relative to
the contaminant distribution. In Figure 6a for example,
it appears that roughly 25 percent of the vapor flows
through uncontaminated soil. The maximum removal
rate for this case is then:

= (1-4) Q Con , (6)

In Figure 6b, vapor flows parallel to, but not through,
the zone of contamination, and the significant mass
transfer resistance is vapor phase diffusion. This would
be the case for a layer of liquid hydrocarbon resting on
top of an impermeable strata or,the water table. This
problem was studied by Johnson et al (1988) -for: the
case of a single component. The solution is:

Rest = 10 Ces
m= 5 (Dw) [In /R)/ (Pain ~ Pa” VRE RE (7)

where:

n = efficiency relative to maximum
removal rate

D = effective soil-vapor diffusion coeffici-
ent [cm*/s}

we = viscosity of air = 1.8 x 10* gicm-s

k = soil permeability to vapor flow [cm’}

H = thickness of screened interval [cm]

R, «= radius of influence of venting well
[em]

R, = venting’ well radius [cm]

Pam = absolute ambient Pressure = = 1016x
10° g/cm-s?

PY = absolute pressure at the venting well
[e/cm-s"]

R,<1r<R, =defines region in which contamina-
tion is present.

Note that the efficiency y is inversely proportional
to the screened interval-thickness H because a larger
interval will, in this geometry, puil in unsaturated air
that has passed above the liquid-phase contamination.
Dis calculated by the Millington-Quirk (Millington and
Quirk 1961) expression, which utilizes the molecular
diffusion coefficient in air D°, the vapor-filled soil poros-
ity €4, and ire total soil porosity ey:

te .

D=D° ea (8)
et

where €, and €, are related by:

EA=Er- POM er.)

Here py and ©m are the soil bulk density [g/cm’] and
soil moisture content [g-H,O/g-soil].

Asan example, consider rémoving a layer of contam-
ination’bounded by sandy soil (k=1 darcy). A 5.1em (4
in) radius vapor extraction well is being’ operated ‘at

0.90 atm (0.91 x 10° picm's’), and the contamination
enone from the region R, = Ry = 5. 1cm to Rz = 9m

(30 ft). The well is screened over a 3m (10 ft) interval.

Assuming that: Moe
“pp = 1.6 g/cm*
Ou = 0.10
D° = 0.087 cm’/s
er = 0.30
R,. = 12m

then the venting efficiency relative to the maximum
removal rate (Equation 2), calculated from Equations 7
through 9 jis:

n = 0.09 = 9%.,

Figure 6c depicts the situation in which vapor flows
primarily past, rather than through the contaminated
soil zone, such as might be the case for a contaminated
clay lens surrounded by sandy soils. In this case vapor-
phase diffusion through the clay to the flowing vapor
limits the removal rate. The maximum removal rate in
this.case occurs when the vapor flow is fast enough to
maintain a low vapor concentration at the permeable/
impermeable soil interface. At any time t a contaminant-
free or “dried out” zone of low permeability will exist
with a thickness 8. An estimate of the removal rate Reg
from a contaminated zone extending from R; to R2 is:

Rex = #(R}~ Ri) Cos D/B(t) (10)

where D is the effective porous media vapor diffusion
coefficient (as calculated previously from Equations 8
and 9) and C,;, is the estimated equilibrium vapor con-
centration (Equation 1). With time 8(t) will grow larger.
In the case of a single component system the dry zone
thickness can be calculated from the-mass balance:

> oe — = Coy, D/S(1) ; ; (ny

Reg = (R?- nV CDCR

where Gi is the residual level of contamination in the
low permeability zone [g-contamination/g-soil], and ail
other variables have. been defined. The solution to
Equations 10 and 11 yields the following equation that
predicts the change in removal rate with time:

2C.4 Dt
t) = ¥ —— 12
&(t) oC, (12)
As an example, consider the case where benzene (C, =
3.19 x 10* g/cm* @20.C) is being removed from a zone
extending from R, = 5.lcm to Rz = 9m. The initial
residual level is 10,000 ppm (0.01 g-benzene/g-soil), p,
= 1.6 g/cm’, De = 0.087 cm’/s, and ey = €A = 0.30. Figure
7 presents the predicted removal rates and “dry” zone
thickness 8(t) as a function of time. Note that it would
take approximately One year to clean a layer 1.5m (5
ft) thick, for a compound as volatile as benzene. Equa-
tion 12 predicts high initial removal rates; in practice,
however, the removal. rate will be limited initially by
the vapor-phase diffusion behavior described previously
for Figure 6b.

Mixture removal rates for the situations ns depicted i in
Figures 6b and 6c are difficult to estimate because





a)

extraction
wells

Figure 11. Venting well configurations.

in a “stagnant” region in the middle of the wells where
air flow would be small in comparison to the flow:
induced outside the triplate pattern boundaries. This
problem can be alleviated by the use of “passive wells”
or “forced injection” welts as illustrated in Figure 11b
(it can also.be minimized by changing the vapor flow
rates from each well with time). A passive well is simply
a well that is open to the atmosphere; in many cases
ground water monitoring wells are suitable. If a passive
or forced injection well is to have any positive effect, it
must be located within the extraction well's zone of
influence. Forced injection wells are simply vapor wells
into which air is pumped rather than removed. One
must be careful in choosing the locations of forced injec-
tion wells so that contaminant vapors are captured. by
the extraction wells, rather than forced off-site. To date
there have not been any detailed reports of venting
operations designed to study the advantages/disadvan-
tages of using forced injection wells. Figure 11¢ presents
another possible extraction/injection well combination.
As illustrated in Figure 9, passive wells can also be used
as vapor barriers to prevent on-site migration of off-
site contamination problems.

For shallow contamination problems (<4m below
ground surface) vapor extraction trenches combined
with surface seals may be more effective than vertical
wells. Trenches are usually limited to shallow soil zones
because the difficulty of installation increases with
depth,

Surface seals, such as polymer-based liners and
asphalt, concrete, or clay caps, are sometimes used to
control the vapor-flow paths. Figure 12 illustrates the
effect that a surface seal will have on vapor-flow pat-

a)
“open soil surface

b)

impermeable seal

Figure 12. Effect of surface seal on vapor flow path.

a)
b)

Pressure gauge :
air-tight monitoring well connection
‘eapiwater sensor assembly wire wo tense «

<e— _ double tffon

inner septa seal
monitoring
well cap

Figure 13. (a) Extraction well construction, and (b) dir-tight
ground water level measuring system.

terns. For shallow treatment zones (<5m) the surface
seal will have a significant effect on the vapor flow paths,
and seals can be added or removed to achieve the
desired vapor flow path. For wells screened below 8m
the influence of surface seals becomes less significant.

Well Screening and Construction oo
Wells should be screened only through the zone of
contamination, unless the permeability to vapor flow is
so low that removal rates would be greater if flow were
induced in an adjacent soil layer (see Figure 6). Removal
rate estimates for various mass-transfer limited sce-

narios can be calculated from Equations 7 and 12.
Based on Equation 5, the flow rate is expected to



assessments,

_« Curtis C. Stanley received his degree in geology with
an engineering minor from North Carolina State Uni-
versity in 1979, He is currently a senior hydrogeologist
for Shell Oil .Co..(Westhollow Research Center, 2236
Two Shell Plaza, Houston, TX 77082) and is responsi-
ble for hydrogeologic response at Shell’s retail facilities.
Stanley is a Certified Professional Geological Scientist
and also a Certified Ground Water Professional with
the NWWA’s Association of Ground Water Scientists
and Engineers. He is also a member of API’s Ground
Water Technology Taskforce and is an EPA Peer
Reviewer.

Marian W. Kemblowski, Ph.D., is a senior research
engineer in the Environmental Science Department at
Shell Development Co. (Westholiow Research Center,
Houston, TX 77082) where he has worked since 1985.
He obtained his M.S. degree in civil engineering from
the Technical University of Warsaw, Poland, in 1973
and his Ph.D. in ground water hydrology from the Insti-
tute for Land Reclamation in Warsaw, Poland, in 1978.
In 1980 - 1981 he was a visiting hydrologist in the New
Mexico School of Mining and Technology. From 1981
to 1985 he worked as an assistant scientist at the Uni-
versity of Kansas, His principal research interests are
in the areas of numerical analysis, transport in porous
media, and ground water monitoring systems.

Dattas L. Byers is a technical associate in the Envi-
ronmental Science Department at Shell Development.

After receiving his B.S. degree in zoology from the Uni-
versity of Nevada, Las Vegas, he was employed by the
Texas Water Quality Board as a quality control chemist
Sor 3% years. In 1977 he joined Shell (Westhollow
Research Center, Houston, TX 77082) where he cur-
rently is providing technical assistance and support for
research in the fate of chemicals in soil and gorund
water, .

James D. Coithart, Ph.D., has been in a variety of
R&D and technical planning positions since joining
Shell (Westhollow Research Center, Houston, TX
77082) in 1966. He has a B.E. from Yale University
and a Ph.D. from Rice University, both in chemical
engineering. Currently he is the research manager of
Shell Development Co. Air, Waste, and Groundwater
Group.

U.S, GOVERNMENT PRINTING OFFICE : 1992 0 - 324-235 QL 3





~ HyperVentilate Users Manual -

To read about these, click on the "Number of Wells” column
heading. Your card SD4 should resemble Figure 32.

Tt is important to recognize that model predictions are intended to
serve as guidelines, and are limited in their ability to describe
behavior that might be observed at any given site. One should use
all the information available, in addition to idealized model
predictions to make rational. decisions about the applicability of soil
venting. ne
Yoi can read about the effect of venting at this site in the article:
“Soil Venting at a California Site: Field Data Reconciled with
Theory", by P. C: Johnson, C. C.-Stanley, D. L. Byers, D. A.
Benson, and M. A. Acton, in Hydrocarbon Contaminated Soils and
Groundwater: Analysis, Fate, Environmental Health Effects, and
Remediation Volume J, P. T. Kostecki and E. J. Calabrese, editors,
” Lewis Publishers, p.253 - 281, 1991. .



ble hydrocarbon. Soi! samples should be analyzed to
determine which contaminants are present at what
levels (contaminant composition). Specific analytical
methods should be used to identify target compounds
(ie., benzene, toluene, or xylenes) and total hydrocar-
bons present. For soil analyses these methods are:

EPA 8240, 8020, 8010 - volatile organic chemicals
(VOCs)

EPA 8270 - semivolatile organic chemicals

EPA 418.1 - total petroleum hydrocarbons (TPH).

The corresponding methods for water samples are:

EPA 8240, 8020, 8010 - volatile organic chemicals
{VOCs)

EPA 8270 - semivolatile organic chemicals

EPA 418.1 - total petroleum hydrocarbons (TPH).

With the current high cost of chemical analyses it
is important to intelligently select which analyses
should be performed and’ which samples should be
sent to a certified laboratory. Local regulations usu-
ally require that a minimum number of soil borings
be performed. and target compounds must be ana-
lyzed based on the suspected composition of the con-
tamination. Costs can be minimized and more data
obtained by utilizing field screening tools, such as
hand-held vapor meters or portable field gas chroma-
tographs (GCs). These instruments can be used to
measure both residual soil contamination levels and
headspace vapors above contaminated soils. At a
minimum, soil samples corresponding to lithology
changes or obvious changes in residual levels (based
on visual observations or odor) should be analyzed.

For complex contamination mixtures, such as gas-
oline, diesel fuel, and solvent mixtures, it is not prac-
tical or necessary to identify and quantify each com-
pound present. [n such cases it is recommended that
a “boiling point” distribution be measured for a
representative sample of the residual contamination.
Boiling point distribution curves, such as shown in
Figure 3 for “fresh” and “weathered” gasoline samples,
can be constructed from GC analyses of the residual
soil contamination (or free product) and knowledge of
the GC elution behavior of a known series of compounds
(such as straight-chain alkanes). Compounds generally
elute from a GC packed column in the order of increas-
ing boiling point, so a boiling point distribution curve
is constructed by grouping all unknowns that elute
between two known peaks (i.¢., between n-hexane and
n-heptane). Then they are assigned an average boiling
point, molecular weight. and vapor pressure. Use of
these data will be explained later.

The cone penetrometer, which is essentially an
instrumented steel rod that is driven into the soil, is
becoming a popular tool for preliminary site screening
investigations. By measuring the shear and normal
forces on the leading end of the rod, soil structure
can be defined and permeability or hydraulic conduc-
tivity can be estimated, Some cone penetrometers are
also constructed to allow the collection of vapor or
ground water samples. This too! has several advan-

y &
PEPPERELL
Pegg edad.
10 +} +} —+- +++ +4
Cumulative "
Weight og
Fraction
0.6: “Fresh” Gasoline
“04
02 “Weathered” Gasoline
00.

40 0 40 80 120 160 «2000-240
T fo

Figure 3. Boiling point distribution curves for samples of
“fresh” and “weathered” gasolines.

tages over conventional soil boring techniques (as a
preliminary site characterization tool): (1) the subsur-
face soil structure can be defined better; (2) no soil
cuttings are generated: and (3) more analyses can be
performed per day.

© Temperature (both above and below ground surface)
Contaminant vapor concentrations are dependent on
temperature, and therefore. removal rates are
strongly influenced by subsurface temperatures.
Above-ground temperatures will influence the selec-
tion of materials and construction of the above-
ground vapor treatment system.

Results from the preliminary site investigation
should be summarized in contour plots, fence diagrams,
and tables in preparation for deciding whether venting
is appropriate, and for the final design of the system.

Deciding if Venting Is Appropriate

As previously stated, the three main factors govern-
ing the behavior of any in situ soil-venting operation
are the vapor flow rate, contaminant vapor concentra-
tions, and the vapor flow path relative to the contamin-
ant location. In an article by Johnson et al. (1988), simple
mathematical equations were presented to help quantify
each of these factors. Following it is illustrated how to
use these.“screening models’and the information col-
lected during the preliminary site investigation to help
determine if in situ soil venting is appropriate at a given
site. In making this decision the following questions will
be answered:

1, What contaminant vapor concentrations are likely
to be obtained?

2. Under ideal vapor flow conditions (i.e., 100 - 1000
scfm vapor flow rates), is this concentration great
enough to yield acceptable removal rates?

3, What range of vapor flow rates can realistically
be achieved?

4. Will the contaminant concentrations and realistic
vapor flow rates produce acceptable removal rates?

5. What residual,-if any. will be left in the soil? What



- HyperVentilate Users Manual -

(O) --> Import Data <-- Saturated Vapor
Concent

FIRST PRESS THE IMPORT
DATA BUTTON!

tration at time=0

| Min Volume w Remove
>90% of Initial Residual

‘Temperature (°C):
‘Conteminant Type:

trait}
Ere

18
Weathered Gasoline

BP #2
Residual
[#vnul]

BP a BP 84
Residual | Residual
[% woul] | (Boel)

BP tS
Residual

11.650
9.263
6.785

24.010
23.982
23.474
22.403
20.771

Figure 31. Card SD7 of the "System Design" stack.

Design Input Parameters...

Please enter (1) the desired time period for

remediation, (2) the design gauge
then (2) click the “update” button.

Now: - click on any wbdle heading t get more info,
- Use tab key W move between cells

vacuum, and

0}

© Come)

Minimum Number of Wells

Description of
Soil Unit

Design | Flowrar per Vapor

Vacuum
(in H20) it

Basedon | Based on Critical

| Medium Sand_

0138.4.

9.2

9.9)

| Chayey Silt.

| 0.0

$43,0)

{Pine Sand

0. 1.9

34.

NA.

NA!

NA!

NA

fo Ls fox bn fn fs bo

NA!

Figure 32. Card SD4 of the "System Design" stack.

34



Vapor Flow Rates...

[Vapor flow rates from each
extraction well and into any injection
wells should be monitored.

Sample measuring devices inchide
pitot mbes, oriface plates and,
rotameters. It is important 19 have
calibrated these devices at the field
operating pressures and temperatures

“Soil Venting Help Stack" Cards

Pressure/Vacuum Readings...

[The vapor concentration and
composition frorn each extraction
well should be analyzed periodically
This data is muiptied by the
extraction well flowrate to caloviate
he removal rate (i.e. ibiday), and
cumulative amount of contaminast
removed.

By itself, vapor concentration data
does nat give a complete picture of

to $f), i is important to monitor the
water table level to ensure that
[comaminated soils remain exposed to
vapor flow. Measuring the water
able bevel during venting is not a
trivia! task because the monitoring
well must remain sealed. Uncapping

BS



- HyperVentilate Users Manual -

Figure 20, Card 20 of the “Soil Venting Stack” stack.
V.3.3 Sample Problem Exercise - Field Permeability Test.

Note: ’ It is recommended that you always plot and visually inspect your data prior
to attempting to fit it to any theory.

In this example, we use HyperVentilate to analyze air permeability test data from the site
pictured in Figure 10. We will focus on results from the lower fine to medium sand zone
(45 - 50 ft below ground surface). Advance to card 20 (Figure 20) of the "Soil Venting
Stack" stack to begin.

Step 1: Location: Card 20 of the "Soil Venting Stack" stack.
Action: Using the right-pointing arrow, advance to card 21 of the “Soil
Venting Stack" stack. Read the text, then click on the "Air
Permeability Test" button.
Result: You are at card AP] of the "Air Permeability Test" stack.

Step 2: Location: Card AP1 of the "Air Permeability Test” stack
Action: — Read the instructions, then click on the "Show Me Set-up" button.
Take a look at the figure, then click the "Return" button to return to
card AP1 of the "Air Permeability Test" stack. Now click on the
"Test Instructions" button.
Result: You are at card AP3 of the "Air Permeability Test" stack.

: Card AP3 of the “Air Permeability Test" stack.





XN.

Number of Venting Wells...

"System Design” Stack Cards

Design Input
(oui seratigrepiy d onctensinent cherectecistics)

€1

Seats tome @ al
nite that you prefer © [Ib)

Pease caer te; disioa ol

ayer, cick on the “Update” buon, and then proceed | © -Clesr All Entries )

too next cand (i.e. click on cight arrow at bosom).

|
La
i

‘Desesipton of

1 ohetiorn S..
2.4 Sores Si.......}

aaa

BBs 225s 5/5

Design Input Now: -click on any uble ending w pot mor inf]
‘Pease exes (1) th denied tine period for uae tab kay to move berwean alla
‘Temodistion, (2) th design gauge vacuum, and
Soyaree pe bone ®
Q ® Mina Namterof Wola
[lime for | Besige | Rowrar per Vepor
Desctipson of mn | Beate ica
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lel aeaal.... 0a rm
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4 Nab. NA ASA
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wale Nal "a pl val

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@  camporicon © “Fresh” Gasoline

‘chooee one) @ “Weathered” Gasoline

+ micimen vehene of vp miedo aceveremacisina

‘De

(ar tmport Date) Seterated Vapor, (aaaEAS] Inet

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. tt

[FIRST PRESS THE DMPORT Min Volume te
DATA BUTTON 294% of Initiat

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Lea? ] Conc.
esi | Bit

bEREEE TL

Removal Efficiency...

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surly conforms 10 our notion of a “sandben”.
‘There are thee geacmal danses of ications tat
veil cass venting ramoval recs © be lem than
(toe prodicand fx te idcal cape. Bach of tieve
‘re dcoated in "A Practical Approach wo the
‘Design, Operusicn, and Monitoring of In Sins Soi
‘Venting Systems". You cn leare mow about
(each by clicking on ths buns w the Bight

In aditen, when contansinmes ws located dose

1 grocnd wars, the effect ofthe varus 6a the
‘water tte level can nificant impact a venting
-syema's performance. To leem about thi, dick
‘90 ths “Ground Water Upweling” bute.



8 Disclaimer

od} The HyperVentilate software package was completed under a Federal Technology Transfer
Act Cooperative Research and Development Agreement between EPA and Shell Oil
d Company, signed in 1990.

EPA is facilitating the distribution of HyperVentilate because the Agency has found the
software and manual to be helpful tools, especially in teaching users about in situ soil
venting and in guiding them through a structured thought process to evaluate the
applicability of soil venting at a particular site. EPA's Office of Underground Storage
Tanks advocates the use of innovative cleanup technologies, and in situ soil venting is
recognized as an effective remediation alternative for many underground storage tank sites.

i HyperVentilate is based on the document titled, “A Practical Approach to the Design,
i. Operation, and Monitoring of Soil Venting Systems" by P. C. Johnson, C. C. Stanley, M.
1 W. Kemblowski, J. D. Colthart, and D. L. Byers, published 1990 by Shell Oil Company.
The program asks a series of questions and forms a “decision tree" in an attempt to identify
the limitations of in situ soil venting for soils contaminated with gasoline, solvents or other
relatively volatile compounds. ‘
EPA and Shell Oil Company make no warranties, either express or implied, regarding the
HyperVentilate computer software package, its merchantability, or its fitness for any
particular purpose. EPA and Shell Oil Company do not warrant that this software will be
error free or operate without interruption. EPA and Shell Oil Company do encourage
testing of this product. ©

EPA will not provide installation services or technical support in connection with the
HyperVentilate computer software package. Neither will EPA provide testing, updating or
debugging services in connection with the enclosed computer software package.

The HyperVentilate computer software package and this manual are not copyrighted.

For anle by the U.S. Government Printing Office
Superintendent of Documents, Mail Stop: SSOP, Washington, DC 20402-9828

2 (993

HEADQUARTERS LIBRARY
ENVIRONMENTAL PHUTECTION AGENCY
WASHINGTGN, D.C. 20460



"Soil Venting Stack” Cards

‘Cacesoed ta "A Practical Appmech © te Design,
‘Opention, ent Motocing of ta Sis Soil Venting
Syvems", Toucan era moo stout ach by
(Ccking om Gs vatons t tried.

Ta atditon, vhen comuminans em lected close ©
(ome weer, ta affect of te vacua on te

Field Tests
[Brier t the ocign of an in site soil

‘Por the syeuse design process, you shoul ensemhi Ge folowing taformetion:

tie plans (showing sukrfae wits, wks, surface sactano, ¢€.)

‘= Plo of te suhrectice (geologic com> sections, weer hie maps, anf soi boing eat Bound eer
+ cxmtumntnant composition (x boing pots: iuivatica)

ee yeomuby eat aan (pecmeebity vals vepar concensrtoas)

> agit channctcirtea (q00end wees patient, eyeticr pemawehaiy, 6.)

Cots Senn



"Soil Venting Stack" Cards

‘This HyperCard Stack was created to help guide environmental scientists
‘through the thought process necessary to decide if and how soil venting might
‘to applied to remediate a given site, The organization end logic of this stack
follows the papar:

A Practical Approach to the Design, Operation,

and Monitoring of In-Sita Soil Venting Systems”
F.C. Johason, C. C. Suaisy, M. W. Kemblowsht, J.D. Cottbast, & D. L. Byers

published in Ground Water Monitoring Review, Spring 1990, p. 159-178

‘Het this potas you do not feel comforuhle with the use of the bunnies, please
itch once wn “?* for mom tsife on the mechanics of this suck...

In-Situ Soil Venting System Design Process
‘You oun cick on any block be this dingsam w grt mors infomnetion shout Get particular sep. Or ou

(can begin at he start of to process by cicking oo sitter te “Leak ox Spi Docowesed® tos, ox Ge
git dinced axow ut the bom of tis cat.

(Lous x 891 Decor)

SE) P=] a)

el

No

[Whenever a soil contamination protiam is detected
or suspected, a site investigation is conducted to
characterize and delineate the 20ns of soil and
|groundveter contamination. in general, the site
[characterization is condurted in two stages. The
lemargeucy response and abatement phase assossas
tho icumediate impact on potentiat tuman and
lecvironmental receptors, and is conducted ina
relatively short pariod of time (days). A detailed
site characterization then follows. Its purpose, like
the emergency response and abstement phase, is to
determine potential migration pathways az assess
the environmental impect associated vith present

[At this point ve will proceed through a
simpte thought process to decide if soil
venting is 2 fonsible alternative. As
{mentioned earlier, the three main factors that
| govern the success of a variting operation are:





- HyperVentilate Users Manual -

Step 3: _ Location: Card H1 of the "Soil Venting Help Stack" siack.

Action: — Play with the buttons and scrolling field. Practice entering a number
in the field in front of “inches”. Place the cursor in the box. It will
change from a hand to an “I-bar” as it enters the field. Hold down
the mouse button and drag the I-bar across the entry, which will
become hilited. Now type in another number, or hit the delete key.
Practice until you feel comfortable selecting text and entering
numbers. Then click on the "Click for Calculation" button. When
you are done practicing, click on the “Return” button.

Result: “Return to the title card of the "Soil Venting Stack" (Figure 2).

Step 4: Location: Title Card:of the "Soil Venting Stack" stack. -
Action: — Click on the "Economics" file folder tab.
Result:, | You are now at card 27 of the "Soil Venting Stack" stack. Take a
. quick glance at this card, which is displayed in Figure 6. *

Step 5: Location: Card 27 of the "Soil Venting Stack” stack.
Action: — Click on the “House” button in the lower left comer.
Result: You are back at the title card (Figure 2).

Step 6: Location: Title card of the "Soil-Venting Stack" stack,
Action: — Click on the "Go to First Card" button.
Result: | You are now at card 1 of the "Soil Venting Stack” stack (Figure 7).

hold button down) to sea costs
associated vith that item.

Economics... FP . "Click" on any item below (8&

For typical service station sites;
clean-up costs can range from
$100K - $250K for the venting
operation alone, depending on
the complexity of the site, clean-
up time, permitting
requirements, and the type of

The two major costs are
generally associated with the
vapor treatment unit and

Figure 6. Card 27 of the "Soil Venting Stack" stack.

Vv.



~ HyperVentilate Users Manual -

Appendix C: "Air Permeability Test" stack cards.



"Aquifer Characterization” Stack Cards _ DI

Aquifer Characterization:

Aquifer Characterization:
These parameters (K and S) can be estimated using the results of » standard tranisicnt

Presa the “References” buon below for more information on slug tests, bail tests,
‘pump tess, and data analysis. ;

Aquifer Characterization:
‘Since most venting systems are installed above “phreatic aquifers” (aquifers with
unconfined upper surfaces), the two primary aquifer parameters needed for design
are:

K = hydraulic conductivity

S = effective porosity (or specific yield)

‘The first parameter represents « convenient combination of the fundamental
| parameters: permeability, density, and viscosity:

ke
Be fuid deoaty

> wcockereson duo w gravity
be vecosity

3. Bear, “Hydraulics of Groundwater", McGraw-Hill, 1979, ISBN 0-07-004170-9,
ep. 463 - 490.

R.A. Froeze and J. A. Cherry, “Groundwater”, Prentice-Hall, 1979, ISBN



- HyperVentilate Users Manual ~

About Soit Ventiag ...

Soil Venting (a.k.a. “in-situ soil
venting”, “vacuum extraction", 8&
“in-situ vapor extraction") is
rapidly becoming one of the most
practiced soil remediation processes

for permeable soils contaminated
with relatively volatile

The underlying phenomena that

influence the success of any soil

| venting operation are easily
understood. By applying a vacuum

More information about soil venting can be found in the following articles:

IM. C. Marley and G. E. Hoag, Induced Soil Venting for the RecaverpfRestarmtion of Gesoline
Hydrocarbons in the Vadose Zone, NWWA/API Conference on Petroleum Hydrocerbons and
‘Ongendc Chemicels in Groundwatr, Houston, TX, 1984.

P. C. Johnson, M. W. KemblowsX, and J. D. Colthart, Practical Screening Models for Soll
in Groundwater, Houston, TX, 1968.

'N. J. Huwler, B. E. Murphy, and J. S. Gierke, Sue of Technology Review: Soil Vapor Extrection
Systems, U.S.E.P.A, CR-814319-01-1, 1988.

D. J. Wilson, A. N. Clarke, and J. H. Clarke, Soil Clean-up by in-situ Aeration. I. Mathematical
Modelling , Sep. Science Tech. , 23:991-1037, 1988.

Figure 9. Card H2 of the "Soil Venting Help Stack” stack.



HyperVentilate
‘Users Manual.

A Software Guidance System Created for Vapor Extraction Applications

A Practical Approach to the
Design, Operation, and
Monitoring of In-Situ Soil
Venting Systems
version 1.01.

Shell O11 Company

a HyperCart Stick Crested by:
Paul C. Johnson, Ph.D.
Amy J. Stabenaa

Shell Development
‘Westhollow Research Center

a Rik: Go to First Card |
by

Paul C. Johnson, Ph.D.

@

Shell Development
Westhollow Research Center
Environmental R&D :
P. O. Box 1380 H
Houston, TX 77251

Apple® MacintoshTM HyperCardTM
compatible version 1.01



- HyperVentilate Users Manual -

Card SD7 of the "System Design" stack.

Read the instructions, then click on the "-->Import Data<--" button.
Your screen should look like Figure 31. The table in the lower part
of the card lists model predictions: vapor concentration and residual
soil concentration (expressed as a percentage of their initial values),
as well as the composition of the residual (expressed as a percentage
of the total for each boiling point range) as a function of the amount
of air drawn through the contaminated soil. Note that as the volume
of air drawn through the soil increases, the vapor concentration and
residual soil levels decrease, and the composition of the residual
becomes richer in the less volatile compounds (BP Range #5). In
the upper right corner of the card are displayed the saturated, or
initial, vapor concentration and the minimum amount of air that must
be drawn through the soil per gram of initial contaminant to achieve
at least a 90% reduction in the initial residual level. This value is
used in future calculations as a design parameter.

: Card SD7 of the "System Design" stack.

Click on the "Return to System Design" button

A dialog box will appear asking: "Transfer Critical Volume Value?".
Click on the "Yes" button. You will now be prompted by another
dialog box asking: "What soil unit # is this value for?". Enter "1"
into the appropriate place then click on the "OK" button. You will
now be transferred back to card SD3 of the "System Design” stack.
Note that the value "128.48" has been entered into the "Critical
Volume of Air**" column for the medium sand soil unit.

: Card SD3 of the "System Design" stack.

Enter "128" into the “Critical Volume of Air**" column for the
clayey silt and fine sand soil units. For this example problem enter
"100" for the efficiency in all three soil units

Card SD3 should now resemble Figure 28.

Card SD3 of the "System Design" stack.

Click on the right-pointing arrow at the bottom of the page to
advance to Card SD4 of the "System Design” stack.

Card SD4 of the "System Design” stack should appear on your
screen.

: Card SD4 of the "System Design” stack.

Assume that you wish to remediate this site in 180 days. Enter
"180" in the "Time for Clean-up" column for each soil unit. Click
on the "Update" button.

HyperVentilate calculates a range of flowrates to a single vertical
well, then uses this value and other input parameters to determine
the minimum number of wells required based on two approaches.

Vv



vapor composition and concentration changes will occur
with time? How do these values relate to the regulatory
requirements?
6. Are there likely to be any negative effects of soil
venting? .
Negative answers to questions 2 or 4 will rule out
in situ soi] venting as a practical treatment method.

What Contaminant Vapor Concentrations Are Likely
to Be Obtained?

Question 1 can be answered based on the results of
soil-vapor surveys, analyses of headspace vapors above
contaminated soi! samples, or equilibrium vapor models
(Johnson et al. 1988). In some cases just knowing which
compounds are present is sufficient to estimate if venting
is feasible. In the absence of soil-vapor survey data,
contaminant vapor concentrations can be estimated.
The maximum vapor concentration of any compound
(mixture) in extracted vapors is its equilibrium or “satur-

ated” vapor concentration, which is easily calculated
from knowledge of the compound's (mixture’s) molecu-
lar weight, vapor pressure at the soil temperature, resid-
ual soil contaminant composition, and the ideal gas law:

xPiMy;
Cost = — 1
wh ep )
where:
Cs, = estimate of contaminant vapor concentration
[mg/L]

x, = mole fraction of component i in liquid-phase
residual (x; = 1 for single compound)

P, = pure component vapor pressure at tempera-
ture T [atm]
M,,; = molecular weight of component i [mg/mole]
R= gas constant = 0.0821 |-atm/mole-°K
T = absolute temperature of residual [°K].
Table 1 presents data for some chemicals and mix-

TABLE 1 .
Selected Compounds and Their Chemical Properties (Johnson et al. 1988)
Compound M, T, (1 atm) PY 20C Cost
. (g/mole) (C) ~ (atm) (mg/L) ©

n-pentane 72.2 36 0.57 . 1700
n-hexane 86.2 69 . 0.16 560
trichloroethane 133.4 75 0.132 720
benzene 78.1 80 0.10 320
cyclohexane 84.2 81 0.10 340
trichloroethylene 131.5 87 0.026 140
n-heptane . 100.2 98 0.046 190
toluene 92.1 11k 0.029 110
tetrachloroethylene 166 121 0.018 . 130
n-octane 114.2 126 0.014 65
chlorobenzene 113 132 0.012 55
p-xylene 106.2 138 0.0086 37
ethylbenzene 106.2 138 0.0092 40
m-xylene 106.2 139 0.0080" 35
o-xylene 106.2 144 0.0066 29
styrene 104.1 145 0.0066 28
n-nonane 128.3 151 0.0042 22.0
n-propylbenzene 120.2 159 0.0033 16
1,2,4 trimethylbenzene 120.2 169 0.0019 93
n-decane . 142.3 173 0.0013 76
DBCP 263 196 . 0.0011 li
n-undecane 156.3 196 0.0006 38
n-dodecane 170.3 216 0.00015 1
napthalene 128.2 218 0.00014 0.73
tetraethyllead 323 dec.@200C 0.0002 26
gasoline’ 95 - 0.34 1300
weathered gasoline? 11 - 0.049 220

‘Corresponds to “fresh” gasoline defined in Table 2 with boiling point distribution shown in Figure 3.
*Corresponds to “weathered” gasoline defined in Table 2 with boiling point distribution shown in Figure 3.
T, (1 atm) - compound boiling point at 1 aim absolute pressure.

M,,- molecular weight.

Cex - equilibrium vapor concentration (see Equation 1).

Py’ (20 C), - vapor pressure measured at 20 C.



- HyperVentilate Users Manual -

Step 12: Location:
Action:
Result:

Step 13: Location:
Action:

Result:

Card 17 of the "Soil Venting Stack" stack.

Read the instructions, then click on the "-->Import Data<--" button.
Your screen should look like Figure 18. The table in the lower part
of the card lists model predictions: vapor concentration and residual
soil concentration (expressed as a percentage of their initial values),
as well as the composition of the residual (expressed as a percentage
of the total for each boiling point range) as a function of the amount
of air drawn through the contaminated soil. Note that as the volume
of air drawn through the soil increases, the vapor concentration and
residual soil levels decrease, and the composition of the residual
becomes richer in the less volatile compounds (BP Range #5). In
the upper right corner of the card are displayed the saturated, or
initial, vapor concentration and the minimum amount of air that must
be drawn through the soil per gram of initial contaminant to achieve
at least a 90% reduction in the initial residual level. This value is
used in future calculations as a design parameter.

Card 17 of the "Soil Venting Stack" stack.

Click on the right-pointing arrow to advance to card 18 of the "Soil
Venting Stack" stack.

You are at card 18 of the "Soil Venting Stack" stack, which should
resemble Figure 19. Read the text. A summary of your input
parameters appears on the right side of this card. At the bottom
appears two calculated values representing the range of the minimum
number of wells required to achieve a 90% reduction in the initial
residual level in the desired remediation time. These values
correspond to idealized conditions, however, they can be used to
gauge the efficacy of soil venting at your site. For example, in this
case the minimum number of wells ranges between 0.7 - 7, which is
not an unreasonable number for a site the size of a service station. If
the range had been 100 - 1000, then it might be. wise to consider
other remediation options.

It is important to recognize that model predictions are intended to
Serve as guidelines, and are limited in their ability to describe
behavior that might be observed at any given site. One should use
all the information available, in addition to idealized model
predictions to make rational decisions about the applicability of soil
venting. .





face vacuum and water table upwelling was monitored.
Figure 18b presents the results. Note that the water
table rise paralleled the vacuum increase, although the
water table did not rise the same amount that the
vacuum did.

Figure 19 compares the reduced measured TPH
vapor concentration C(t)/C(t=0) with model predic-
tions, C(t=0) was taken to be the vapor concentration
after one pore volume of air had passed through the
contaminated zone (=80 mg/L), m(t=0) is equal to the
estimated spill mass (=4000 kg), and V(t) is the total
volume of air that has passéd through the contaminated
zone. This quantity is obtained by integrating the total
vapor flow rate with time, then multiplying it by the
fraction of vapors passing through the contaminated
zone ¢ (=0.33). As discussed, the quantity @ was esti-
mated by comparing soil-gas concentrations from the
vadose.zone monitoring installations with vapor concen-
trations in the extraction well vapors. There is good
quantitative agreement between the measured and pre-
dicted values.

Based on the data presented in Figures 15 through
19 and the model predictions in Figure 8, it appears that
more extraction wells (~ 10 more) are needed to reme-
diate the site within a reasonable amount of time (< 2
years).

Conclusions

A structured, technically based approach has been
Presented for the design, construction, and operation
of venting systems. While an attempt has been made to
explain the process in detail for those not familiar with
venting. operations or the underlying governing phe-
nomena, the most effective and efficient systems can
only be designed and operated by personnel with a good
understanding of the fundamental processes involved.
The service station spill example presented supports the
validity and usefulness of this approach.

There are still many technical issues that need to be
resolved in the future. The usefulness of forced or pas-
sive vapor injection wells is often debated, as well as
other means of controlling vapor flow paths (impermea-
ble surface covers, for example). A well-documented
demonstration of the effectiveness of soil venting for
the removal of contaminants from low-permeability
soils is also needed. It is clear from the simplistic model-
ing results presented in this paper that venting will be
less effective in such situations. Without a comparison
with other viable treatment alternatives, however, it is
difficult to determine if soil venting would still be the
preferred option in such cases. Other topics for future
study include: enhanced aerobic biodegradation by soil
venting, the possibility of decreasing residua? contami-
nant levels in water-saturated zones by air sparging/
vapor extraction, and optimal operation schemes for
multiple vapor extraction well systems.

References
Bear, J.1979. Hydraulics of Groundwater, McGraw-Hill.
Dev, H., G.C. Sresty, J.E. Bridges, and D. Downey,

COOC(=®) predicted
* — CONC(t=0) measured

_ 08
C(H/C(t=0)

md) b00 ke

3,4 $5 6
Vp/m(t=0) (/g) ..

Figure 19. Comparison of model predictions and messured

response.

1988. Field test of the radio frequency in situ soil
decontamination process. In Superfund '88: Proceed-
ings of the 9th National Conference, HMCRI, Novem-
ber 1988.

Hutzler, N. J., B.E. Murphy, and J.S. Gierke. 1988. State
of Technology Review: Soil Vapor. Extraction Sys-
tems, U.S EPA, CR-814319-01-1.

Johnson, P.C.; M.W. Kemblowski, and J.D. Colthart.
1988. Practical screening models for soil venting
applications..In Proceedings of NWWA/API Confer-
ence on Petroleum Hydrocarbons and Organic Chem-
icals in Ground Water, Houston, Texas.

Marley, M.C., and G.E. Hoag. 1984 Induced soil venting
for the recovery/restoration of gasoline hydrocarbons
in the vadose zone. In Proceedings of NWWA/API
Conference on Petroleum Hydrocarbons and Organic
Chemicals in Ground Water, Houston, Texas.

Millington, R.J. and J.M. Quirk. 1961. Permeability of
Porous Solids, Trans. Faraday Soc., 57:1200-1207.

Salanitro, J. P., M.M. Western, and M.W. Kemblowski.
1989. Biodegradation of aromatic hydrocarbons in
unsaturated soil microcosms. Poster paper presented
at the Fourth National Conference on Petroleum
Contaminated Soils, University of Massachusetts,
Amherst, September 25-28.

Wilson, D. J., A.N. Clarke, and J.H. Clarke. 1988 Soil
Clean-up by in situ aeration. I. Mathematical Modell-
ing, Sep. Science Tech., vo]. 23 pp. 991-1037.

Biographical Sketches

Paul C. Johnson, Ph.D., joined Shell
Development Co.’s (Westhollow Research Center,
Room EC-649, P.O. Box 1380, Houston, TX 77251-
1380) Environmental Science Department in 1987 after
earning his B.S. in chemical engineering from the Uni-
versity of California, Davis, and his Ph.D. in chemical
engineering from Princeton University. His current.

- areas of research include the development and evalua-

tion of soil treatment processes, modeling and measur-
ing transport phenomena in porous media, and the
development of transport models for predicting emis-
sions and exposures used in envvironmental risk





- HyperVentilate Users Manual -

Step 3: Location: Card 24 of the "Soil Venting Stack” stack.
Action: Select "Number of Extraction Wells" from the list of options.
Result: | Card SD1 of the "System Design” stack should be displayed, as
pictured in Figure 26.

Step 4: Location: Card SD1 of the "System Design" stack. ‘
Action: Read the text, then use the right-pointing arrow to advance to card
SD2.
Result: Card SD2 of the “System Design" stack should be displayed.

Step5: Location: Card SD2 of the “System Design" stack.
Action: Read the instructions on the card, enter the following values into the
table, then click on the “Update” button: .

: Soil Zone ~
Parameter Medium Sand __Clayey Silt Fine Sand
subsurface interval (ft BGS) 10-30 30-43 - 43 - 50
description of contaminant gasoline gasoline gasoline
radial extent of contamination (ft) 20 20 20
interval thickness (ft) 20 13 7°
average contaminant concentration 100 1000 10000

Result: | Card SD2 should now resemble Figure 27.

Step6: Location: Card SD2 of the "System Design" stack.
Action: — Use the right-pointing arrow to advance to card SD3 of the "System
Design" stack.
Result: Card SD3 of the "System Design" stack should be displayed.

Step7: Location: Card SD3 of the "System Design” stack.
Action: Read the text. Note that "clicking" on many of the table headings
will take you to "help" cards. Take a few minutes to explore the
use of these, then enter the following information:

Soil Zone .
Parameter Medium Sand_Clayey Silt Fine Sand
permeability (darcy) * 10-100 0.01 - 0.1 1-10
design vacuum (in H20) 40 40 . 40
Well Construction:
Radius of Influence (ft) 40 40 40
Extraction Well Radius (in) 2 2 2
Extraction Well Screen Thickness (ft) 10 5 3



- HyperVentilate Users Manual -

Appendix A: "Soil Venting Stack" stack cards.



Equation 4 was used to calculate Racceptable- ASSum-
ing Mspin = 4000kg and + = 180 d, then:

Racceptabie = 22 kg/d

Using Equation 2, C.. = 240 mg/L, and Q = 2800
min (100 cfm):

Res = 970 kg/d
which is greater than Racceptable-
© What range of vapor flow rates can realistically be

achieved?

Based on boring logs, the contaminated zone just
above the water table is composed of fine to medium
sands, which have an estimated permeability i< k < 10
darcy. Using Figure 5, or Equation 5, the predicted flow
rates for an extraction well vacuum P,, = 0.90 atm are:

0.04<Q<04m%m-min Ry =5.tcm, Ry = 12m

0.43 <Q<43 ftvft-min R, = 2.0 in, R, = 40 ft.

The thickness of this zone and probable screen thick-
ness of an extraction well is about 2m (6.6 ft). The total
flow rate per well through this zone is estimated to be
0.08<Q<0.8 m*/min (2.8 cim<Q<28 cfm).

@ Will the contaminant concentrations and estimated
flow rates produce acceptable removal_rates?

Using C.s=240 mg/L, the maximum removal rates
likely to be obtained are’ calculated from Equation 2:

28 kg/d < (Res)max < 280 kg/d. *

Tobe conservative, we will guess that only 50 percent.

of the vapor actually flows through contaminated soils,

s0 our estimated removal rate per well will be half of,

these values. The estimated acceptable removal rate
Racceptable = 22 kg/d falls within this range. Of course
this calculation did not take into account the possibility
of vapor concentration decreases during venting. This
will be taken into account in the next subsection.

@ What residual, if any, will be left in the soil?

A target cleanup level for most gasoline spill sites
is <1000 mg/kg TPH residual; in some states the target
level is <100 mg/kg TPH. If the initial residual level is
~10,000 ppm, then at least 90 percent of the initial
residual needs to.be removed. According to the curves
in Figure 8, which represent the maximum removal rates
for the gasoline analyzed at this site, approximately 100
I-vapor/g-residual will have to pass through the conta-
minated zone to achieve this target. Based on our esti-
mated initial residual of 4000kg TPH, 4 x 10° I-vapor
are required. Over a six-month period this corresponds
to an average flow rate Q=1.5 m’/min (54 cfm). Recall
that since this corresponds to the maximum removal
rate, it is the minimum required flow rate.
® Are there likely to be any negative effects of soil vent-

ing?

Given that the contaminated soils are located just
above and below the water table, water table upwelling
during venting must be considered here.

Air Permeability Test

Figure 16 presents data obtained from the air per-
meability test of this soil zone. In addition to vapor
extraction tests, air injection tests were conducted. The
data are analyzed in the same manner as discussed for
vapor extraction tests. Accurate flow rate (Q) values
‘were not measured, therefore, Equation 17 was used to

a oy =x
) Cy
Pressure -2 fee a
Decrease 9
Gn H,0) 4
a
“2 -3
4 o
. a
a
84(o BD 34m] 9 On g
‘|& HB-6D (r=16.m) a
|. HB-14D (7=9.8 m)
10.
1 10. 100 1000
Time (min)
b)
¥ 50
a HED (34m)
Pressure gy | | HB-6D (16m) of?
Increase 9 HB-MD (98m)
(aH,0) + B10 (=76m)| 9
7 em
o
2». F fo?
ge to
#9
10 at ao
a 4t,o
Oto?
fy a ne Oe
1 10 100 1000
Time (min)

Figure 16. Air permeability test results: (a) vapor extraction
test; (b) air injection test. (In HO] denote vacuums expressed
as equivalent water column heights.

determine the permeability to vapor flow. The k values
ranged from 2 to 280 darcys, with the median being ~8
darcys.

System Design

@ Number of vapor extraction wells:

Based on the 8 darcys permeability, and assuming
a 15cm diameter (6 in) venting well, a 2m screened
section, P;, = 0.90 atm (41 in H2O vacuum) and R,=12m,
then Equation 5 predicts: ‘

Q = 0.7 m/min = 25 cfm : :

Based on the preceding discussion, a minimum aver-
age flow rate of 1.5 m/min is needed to reduce the
residual to 1000 ppm in six months. The number of wells
required is then-1.5/0.7 = 2, assuming that 100 percent
of the vapor flows through contaminated soils. It is not
likely that this will occur, and a more conservative esti-
mate of 50 percent vapor flowing through contaminated
soils would require that twice as many wells (four) be
installed.

A single vapor extraction well (HB-25) was installed
in this soit layer with the knowledge that more wells
were likely to be required. Its location and screened
interval are shown in Figure-15. Other wells were installed
in the clay layer and. upper sandy zone, but in this paper
only results from treatment of the lower contaminated



- HyperVentilate Users Manual -

Read the text, look at the sample data (click on the "show me sample
data” button) then enter the following values for this example:

__ Soil layer thickness = 6.6 ft
___ estimated radius of influence = 50 ft
__ air permeability test flowrate =15CFM

Click on the "-->Calculate<—" button to estimate how long the air
permeability test should be conducted.
Your results should match those displayed below in Figure 21.

: Card AP3 of the "Air Permeability Test" stack.
Click on the "Return" button to return to card AP1 of the "Air
Permeability Test" stack. Then click on the "Data Analysis” button.
You are now at card APS of the "Air Permeability Test" stack.

Card APS of the "Air Permeability Test" stack.

Read the text, then step through cards AP6 and AP7, until you reach
card AP8 of the "Air Permeability Test” stack.

You are now at card AP8 of the “Air Permeability Test" stack.

Air Permeability Test - Lastractions

1)
dentify soil zones to be treated

2) Pore Yolume Estimation:
Install vapor extraction well(s) in this Ener
zone(s). Existing monitoring vells ‘

. 1) Soil Layer Thickness [ft]:
may be used, when the screen interval 2) Estimated Radius of Influence (ft):
extends only into the zone to be treated. 3) Air Perm. Test Flowrat [CFM]:
Note the extraction vell radius and

borehole size. Insure that the well is

not “connectéd” to other soil zones :
. Pore Yolune: 15543
through the borehole (use cernent/grout Bid lime wp Extract a Pore Voiume-[0.72

to seal annular borehole region).

Figure 21. Card AP3 of the "Air Permeability Test" stack.



zone will be discussed. A ground water pumping well was
installed to maintain a 2m drawdown below the static water
level. Its location is also shown in Figure 15.__

System Monitoring

Three vadose monitoring wells similar in construc- ~

tion to the one pictured in Figure 14 were installed so
that the soil temperature, soil-gas concentrations, and
subsurface pressure distribution could be monitored at
three depths. One sampling port is located in the zone
adjacent to the aquifer. The vapor flow rate from HB-
25 and vapor concentrations were measured frequently,
and the vapor composition was determined by GC-FID
analysis. In addition, the water level in the ground water
monitoring wells was measured with the system pictured
in Figure 13b. The results from the first four months of
operation are discussed in following text

In Figure 17a the extraction well vacuum and corre-
sponding vapor flow rate are presented. The vacuum
was maintained at 0.95 atm (20 in H2O vacuum), and
the flow rate was initially 12 scfm. It gradually decreased
to about 6 scfm over 80 d. For comparison, Equation S
predicts that Q=12 cfm for k=8 darcys. Increasing the
applied vacuum to 0.70 atm (120 in HzO vacuum) had
little effect on the flow rate. This could be explained
by increased water table upwelling, which would act to
decrease the vertical cross section available for vapor
flow. The scatter in the flow rate measurements is prob-
ably due to inconsistent operation of the ground water
pumping operation, which frequently failed to perform
properly.

Figure 17b presents the change in vapor concentra-
tion with time. Fifteen specific compounds were identi-
fied during the GC-FID vapor analyses; in this figure
the total concentration of known and unknown com-
pounds detected between five boiling Point ranges are
presented:

methane - isopentane (<28 C)

isopentane - benzene (28 - 80 C)

benzene - toluene (80 - 111 C)

toluene - xylenes (111. - 144 C)

>xylenes (>144 C).

There was a shift in composition toward less volatile
compounds in the first 20 days, but after that period
the composition remained relatively constant. Note that
there is still a significant fraction of volatile compounds
present. Within the first two days the vapor concentra-
tion decreased by 50 percent, which corresponds to the
time period for the removal of the first pore volume of
air. Comparing the subsequent vapor concentrations
with the concentrations measured in the vadose zone
monitoring wells indicates that only (80 mg/L)/(240 mg/
L)*100=33% of the vapors are flowing through contamin-
ated soil.

Figure 18a presents calculated removal rates (flow
fate x concentration) and cumulative amount (1 gal =
3 kg) removed during the first four months. The
decrease in removal rate with time is due to a combina-
tion of decreases in flow rate and hydrocarbon vapor
concentrations. After the first four months approxi-
mately one-fourth of the estimated residual has been

Time @

0 20 © © . % 10. 120

Time (4)
Figure 17. Soil-venting results: (a) vacuumv/flow rate data,
(b) concentration/composition data.
a) @ > 400 «

© Cumulative
Recovered
(gal)

b)

Time (min)
1f1H,0} denove vacuums expressed as equivalent water column heights

Figure 18, Soil-venting results: (a) removal rate/cumulative _
recovered, (b) water table. rise.

removed from this lower zone.
On day 80 the vacuum was increased from 20 - 120
in HO vacuum and the-subsequent increase in subsur--



- HyperVentilate Users Manual -

V.2. General Features of Cards

Figures’4 and 5 are examples of cards from the "Soil Venting Stack” stack and "System
Design" stack. There are a few general features. of these cards that users should
understand: : :

a) Each card (with the exception of the first card of the "Soil Venting Stack" stack) has
been numbered for easy reference with the printouts given in Appendices A through
F. In the "Soil Venting Stack" these numbers appear in the bottom center of each
card (i.e. number "3" in Figure 4). In other stacks these numbers appear at either
the top or bottom comers of the card (i.e. "SD1" in Figure 5).

b) Arrow buttons are included at the bottom of some cards. Clicking on right-pointing
arrow will advance you to the next card in the stack; clicking on the left-pointing
arrow will take you in the opposite direction. :

¢) The identifying card numbers in the “Soil Venting Stack" stack are also fields into
which text can be typed. You can skip to other parts of the "Soil Venting Stack"
stack by selecting this field, typing in the card number of your destination (within
the “Soil Venting Stack"), and then hitting the “return" key.

d) Many cards have a house button in the lower left corner. Clicking on this button
will take you to the first card of the "Soil Venting Stack" stack, which is the card
displayed at start-up (see Figure 2).

In-Situ Soil Venting System Design Process
You cen click on any block in this diagram t get more information about thet particular step. Orgoe

can begin at the start of he process by clicking on either he “Leak or Spill Discovered" box, or the
right-directed arrow at the bottom of this card.

Preliminary Site
Investigation

Screen Treatment

«Hs

Print Flow Diagram,

Figure 4. Card 3 of the "Soil Venting Stack" stack.
Vv.



- HyperVentilate Users Manual -

Appendix E: "System Design" stack cards.



tures accidentally released to the environment. There
are more sophisticated equations for predicting vapor
concentrations in soil systems based on equilibrium par-
titioning arguments, but these require more detailed
information (organic carbon content, soil moisture) than
is normally available. If a site is chosen for remediation,
the residual total hydrocarbons in soil typically exceed
500 mg/kg. In this residual concentration range most of
the hydrocarbons will be present as a separate or “free”
phase, the contaminant vapor concentrations become
independent of residual concentration (but still depend
on composition), and Equation 1 is applicable (Johnson
et al. 1988). In any case, it should be noted that these
are estimates only for vapor concentrations at the start
of venting. which is when the removal rates are generally
greatest. Contaminant concentrations in the extracted
vapors will decline with time due to changes in composi-
tion, residual levels, or increased diffusional resistances.
These topics will be discussed in more detail.

Under Ideal Vapor Flow Conditions (ie., 100 - 1000
scfm Vapor Flow Rates), Is This Concentration Great
Enough to Yield Acceptable Removal Rates?
Question 2 is answered by multiplying the concentra-
tion estimate C,,,, by a range of reasonable flow rates,
Q:
Res = Ces: Q (2)

Here R,., denotes the estimated removal rate, and
C.s, and Q must be expressed in consistent units. For
reference, documented venting operations at service sta-
tion sites typically report vapor flow rates in the 10 -
100 scfm range (Hutzler et al. 1988), although 100 —
1000 scfm flow rates are achievable for sandy soils or
large numbers of extraction wells. At this point in the
decision process what is still being neglected is that
vapor concentrations decrease during venting due to
compositional changes and mass transfer resistances.
Figure 4 presents catculated removal rates Res, [kg/d]
for a range of C,., and Q values. C.., values are presented
in [mg/L] and [ppmcua] units; where [ppmcya] tepresents
methane-equivalent parts-per-million votume/volume
(ppm,) units. The [ppmcy44] units are used because field
analytical tools that report (ppm,] values are often cali-
brated with methane. The [mg/L] and [ppmgya] units are
related by:

[ppmcys] * 16000 mg-CH,/mole-CH, * 10%

(0.0821 ]-atm/°K-mole) * (298 K) @)

[emg/L] =

For field instruments calibrated with other compounds
(i.e., butane, propane), [ppm,] values are converted to
[mg/L] by replacing the molecular weight of CH, in
Equation 3 by the molecular weight [mg/mole] of the
calibration compound. —

Acceptable or desirable removal rates Racceptable CaN
be determined by dividing the estimated spill mass Mepin,
by the maximum acceptable cleanup time 7:

Racceptabte = Mspin/t (4)

For example, if 1500kg (~ 500 gal) of gasoline had
been spilled at a service station and it was wished to

(PPM ey)
133 1330 15300 153000
a a

10053

for
T mT bi
a A. 1 10 100
_ Vapor Concentration (mg/l)

* Gomey,) - concentration in meane equivalent ppm (volo) nits

Figure 4. In situ soil-venting removal rate dependence on
vapor extraction rate and vapor concentration.

complete the cleanup within eight months, then Raccepta-
ble = 6.3 kg/d. Based on Figure 4, therefore, C.. would
have to average >1.5 mg/L (2400 ppmcia) for-Q=2800
min (100 cfm) if venting is to be an acceptable option.
Generally, removal rates <1 kg/d will be unacceptable
for most releases, so soils contaminated with compounds
(mixtures) having saturated vapor concentrations less
than 0.3 mg/L (450 ppmeys) will not be good candidates
for venting, unless vapor flow rates exceed 100 scfm.
Judging from the compounds listed in Table 1, this corre-
sponds to compounds with boiling points (T,)>150 C,
or pure component vapor pressures <0.0001 atm evalu-
ated at the subsurface temperature.

What Range of Vapor Flow Rates Can Realistically
Be Achieved?

Question 3 requires that realistic vapor flow'rates for
the site-specific conditions be estimated. Equation 5,
which predicts the flow rate per unit thickness of well
screen Q/H [cm* /s], can be used for this purpose:

Q_ kK U- CamPe)l
HO Pe inRYR) °

= soil permeability to air flow [cm? | or [darcy]
viscosity of air = 1.8 x 10“ g/cm-s or 0.018 cp

Py, = absolute pressure at extraction well [g/cm-s’}
or [atm]

Paim = absolute ambient pressure ~ 1.01 x 10° g/cm-s*
or 1 atm

R,° = radius of vapor-extraction well [cm]

R, = radius of influence of vapor extraction well
fem]. .



B Field:
‘Butons have been placed in each | Fields may contain information, or they may be
card, Clicking on any button will] place for you to input numbers,
perform an action, such as:

Glick co arrows w move
‘excep or down

‘Help: In-Situ Soil Venting System Design Process
‘This is the decision process that one must follow to:
1) decide if soil venting is applicable at a given site

& :

2) design an effective soil venting system

[kis an abridged vertion of Figure 2 in "A Practical Approach 10 the Design,
Operation, & Monitoring of In-Situ Soil Venting Syatema", by P. C. Yoknson,
C.C. Sunley, M. W. Kemblowai, J. D. Colthart, and D. L. Byers. -

"Soil Venting‘Help Stack" Cards B1

Mone information sbout sil venting can te found inthe following aries:

MC. Macey and O. 2. Hoag, Induced Soil Veating forthe Recowery/Resteration of Cesaline
Hydrocarbons i the Vedewe Zane, NWWAJAPI Conference on Pecoleun Ryérocarbosa and
Organic Chezsicals in Groundwater, Honetan, TX, 1984,

P.C.Jetmson, MW. Kexablewsk, esd J.D. Cohan, Practical Screning Model or Sel
| Veating Applications, NWWAJAPI Conference on Petroleum i
in Groundwaes, Houston, TX, 1968.

.1, Hamer, B. E. Map, ent J.S. hte, oof Tey evel Vie rn
Syma, USEPA, CRAIOI9-01-1, 1988.

D1. Wilson, AX. Carte, and J. Care, So Cean-p by insite Acrain. 1. Masbate!
Modeling, Sep. Science Toch., 23991-1037, 1988.

Help: Preliminary Site Investigation

oy

|More information about site investigation and remediation can be found in the
following articles:

| API Publication 1628 .

"A Guide to the Assessment and Remediation of Underground Petroleum
Releases",

American Petroleum Institute, 1220 1. Street Northwest, Washington DC, 20005 ,|

to a high-temperature Combustion
[chamber

ota Kiln, fixed hearth, maliple



"Soil Venting Help Stack" Cards B3

‘A complete tite essessment must determine the following:

i
fle

Contaminant Delineation # Compound Name
‘eamat of fee-phere hydrocarbon

88

pores

T
2
3
la
s
é
I
5
9

it

10

HTH

Zewwensoney

Help: 6b) Liquid Layers

Let's Do @ Caicuiation



SOFTWARE held by Library
Database Coordinator,
please inquire at Circulation Desk



- HyperVentilate Users Manual -

This HyperCard Stack was created to help guide environmental scientists
through the thought process necessary to decide if and how soil venting might
be applied to remediate a given site. The organization and logic of this stack
follows the paper:

"A Practical Approach to the Design, Operation,
and Monitoring of In-Situ Soil Venting Systems”

vy:
P. C. Johnson, C. GC. Stanley, M. W. Kemblowski, J. D. Colshart, & D. L. Byers

published in Ground Water Monitoring Review, Spring 1990, p. 159-178

If at this point yor do not feel comfortable with the use of the buttons, please
click once on °?* for more info on the mechanics of this stack...

Figure 7. Card 1 of the "Soil Venting Stack" stack.

Step7: Location: Card 1 of the "Soil Venting Stack" stack.
Action: Click on the right-pointing arrow.
Result: You are now at Card 2 of the "Soil Venting Stack" stack (Figure 8).

Step 8: Location: Card 2 of the "Soil Venting Stack” stack.

Action: Read the text, and click on the "down" and "up" arrows on the
displayed text field under “About Soil Venting..." to make the
field scroll. Then click on the left-pointing arrow at the card bottom.

Result: You are now back at card 1 of the "Soil Venting Stack" (Figure 7).

Step9: Location: Card 1 of the "Soil Venting Stack” stack.
Action: — Click on the right pointing arrow. .
Result: You are again at card 2 of the "Soil Venting Stack" stack (Figure 8).
By now you should feel comfortable using the left- and right-
pointing arrows to travel through the stack.

Step 10: Location: Card 2 of the "Soil Venting Stack" stack.

Action: — Click on the "?" button in the lower right comer of the card. This
button indicates that there is a "Help" card containing additional
information.

Result: | You are now at card H2 of the "Soil Venting Help Stack” stack
(Figure 9). Scroll through the list of references, then click on the
"Retum”" button to return to card 2 of the "Soil Venting Stack" stack.

At this point you should feel comfortable navigating around in HyperVentilate.