c/EPA
Uniled States
Environmental Protection
Agency
EP/V540/M5-89/003
April 1989
CIV



SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
MMi
Demonstration Bulletin
In-Situ Vacuum Extraction
Terra Vac, Inc.
TECHNOLOGY DESCRIPTION: This in-situ
vacuum extraction technology is a process for the
removal and venting of volatile organic compounds
(VOCs) from the vadose or unsaturated zone of soils.
Often, these compounds can be removed from the
vadose zone before they have a chance to
con:aminate groundv/ater. In using this technology,
subsurface organic contaminants are "vacuumed up"
via a well, vapor/liquid separated, and then exposed
to activated carbon before the "vapor" is allowed to
be released into the atmosphere.
The technology uses readily available components
such as extraction and monitoring well(s), manifold
piping, vapor/liquid separator, vacuum pump, and
emission control equipment, such as activated carbon
cansters. Once a contaminated area is completely
defined, an extraction well (or wells) is installed
(depending upon the extent of contamination) and is
connected by piping :o a vapor/liquid separator device
(Figure 1). A vacuum pump draws the subsurface
contaminants through the well, separator device, and
an activated carbon canister before discharge of the
air streams is allowed to the atmosphere. Subsurface
vacuum and soil vapor concentration are monitored
via i/adose zone monitoring wells.
The technology does not require highly trained
operators or soil excavation, and it also is not depth
limited. The technology works best when it is applied
towards the remediation at s tes which are
contaminated by liquids having high vapor pressures.
However, the process is limited in applicability;
diffusion rates through dense soils (such as
compacted clays) are much lower than through sandy
soils, and if activated carbon is used, then spent
carbon must be processed. In addition, depending on
the soil type and the depth to groundwater, the radius
of influence of a single extraction well can range from
tens to hundreds of feet. Typical contaminant
recovery rates also range between 20 and 2500
pounds per day and are a function of volatility of the
organic compound recovered. Therefore, the more
volatile the organic compound, the faster the process
works. The developer also states that the process is
more cost effective where contaminated soils are
predominantly above the water table, although
systems have been designed for vapor and
groundwater recovery.
WASTE APPLICABILITY: This technology is
applicable to organic compounds that are highly
volatile at ambient temperatures in soils and
groundwater.
Vacuum
Pump
Skid
Suck
S«coiid*ry
Activated
Cartoo
Canister

1

f





Tank
Truck
Primary
Activatr-d
Carbon
Canisters
Figure 1.
Process diagram for in-situ vacuur
extraction.

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Table 1. Reduction of Weighted Average TCE Levels in Soil
TCE Concentrations (mg/kg)
Extraction Well
Pretreatment
Posttreatment
% Reduction
e
1
33.98
- 29.31
13.74

2
3.38
2.36
30.18

3
6.89
6.30
8.56

4
96.10
4.19
95.64
e
Monitoring Well

I


1
1.10
0.34
69.09

2
14.75
8.98
39.12
e
3
227.31
84.50
62.83

4
0.87
1.05
-

DEMONSTRATION RESULTS: The in-situ vacuum
extraction demonstration occurred at the Groveland
Wells Superfund Site in Groveland, Massachusetts.
Four extraction wells were employed to pump
contaminants to the process system. Four monitoring
wells were utilized to measure the impact of treatment
on site contamination. During the SITE demonstration,
1300 pounds of volatile organics, mainly TCE, were
extracted during a 56-day operational period. The
volatiles were removed from both highly permeable
strata and low permability clays.
The demonstration operated from December
1987 to April 1988.
The process successfully removed:
Trichloroethylene
(all volatile compounds)
Concentrations of volatile organic compounds in
the soil gas were reduced 95% during the 56-
day operational period.
Contaminated water that is collected may
require further treatment.
Care must be taken during equipment design
and set-up to correctly size the carbon
collection canisters, insulate above-ground
apparatus, and shield the vacuum blower.
• The system runs with little operator attention.
FOR FURTHER INFORMATION:
EPA Project Manager:
Mary K. Stinson
U.S. EPA Risk Reduction Engineering Laboratory
Woodbridge Avenue
Edison, New Jersey 08837
201-321-6683 FTS: 340-6683
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/540/M5-89/003

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