borehole was performed per one monitoring well. The MIP provides semi-quantitative
data on the presence of volatile organic compounds (VOCs) in the soil and it allows
delineation of the VOCs source (see Chap. 31 for details). Dual tube soil sampling
(Geoprobe Systems
®
, USA) was later utilized to collect four discrete soil samples in
accordance with the standard guide (ASTM 1998) in the nearby soil monitoring probe.
The material was also collected for in situ microcosm experiments.
19.2.3 Remediation Pilot Test Setup
Three different oxygen release compounds were injected near three different monitoring wells (approximately 25 m from one another) situated in the center of the
contamination plume. The injections were performed via direct push top-down
method into the subsurface using Geoprobe 7822 DT drilling rig together with
Geoprobe Pressure-Activated Injection Probe (Geoprobe Systems
® , USA) and
Wanner G10 diaphragm pump (Wanner Engineering, Inc., USA). ORCs tested
were as follows: calcium peroxide (purity of 75%; Ixper 75c, Solvay, Belgium)
as a typical compound used as oxygen source; modified calcium peroxide – 1:1
mixture of calcium hydroxide oxide and calcium peroxide (ORC Advanced
® and
ORC
® Primer, Regenesis, USA) that should provide oxygen release in longer term;
and gelatinous hydrogen peroxide (OXYGEL, Biorem, Belgium) which slowly
releases hydrogen peroxide from the gel matrix. The oxygen release materials were
injected directly into the probes (injection flowrate and pressure 30 L/min, 6–20 bar,
respectively). Four to five injection horizons per probe were performed on the basis
of the MIP profile from the nearby MIP probe. An example of the targeted injection
scheme based on the MIP profile is shown in Fig. 19.1.
The materials, regardless of their actual chemical structure, were injected at the
amount capable of releasing 17 kg of O 2 per borehole. In case of calcium peroxide
and modified calcium peroxide, this means that 100 kg of material diluted in 500 L
of water taken from the aerated bioreactor used within the pump-and-treat technology installed further on site was injected per one injection point. Gelatinous hydrogen peroxide contains 10.6% of releasable oxygen and therefore 160 kg of the
product mixed with 140 L of water taken from the aerated bioreactor was injected
per one injection point.
Mixing water from the aerated bioreactor contained significant numbers of
bacteria capable of aerobic biodegradation, although these bacteria were probably
significantly inhibited by the high pH of the suspensions (and presence of hydrogen
peroxide), some might have survived and later helped to enhance biodegradation of
target contaminants. The scheme of the field study layout is displayed in Fig. 19.2.
The distance between the injection points and the monitoring well was approximately 1.5 m. MIP and soil monitoring probes were approximately 0.75 m far from
the monitoring well.
MIP and soil monitoring probes were performed prior to the injection and the
holes were sealed by cement afterwards.
19 Field Study VII: Field Study of Three Different Injectable. . .
413
data on the presence of volatile organic compounds (VOCs) in the soil and it allows
delineation of the VOCs source (see Chap. 31 for details). Dual tube soil sampling
(Geoprobe Systems
®
, USA) was later utilized to collect four discrete soil samples in
accordance with the standard guide (ASTM 1998) in the nearby soil monitoring probe.
The material was also collected for in situ microcosm experiments.
19.2.3 Remediation Pilot Test Setup
Three different oxygen release compounds were injected near three different monitoring wells (approximately 25 m from one another) situated in the center of the
contamination plume. The injections were performed via direct push top-down
method into the subsurface using Geoprobe 7822 DT drilling rig together with
Geoprobe Pressure-Activated Injection Probe (Geoprobe Systems
® , USA) and
Wanner G10 diaphragm pump (Wanner Engineering, Inc., USA). ORCs tested
were as follows: calcium peroxide (purity of 75%; Ixper 75c, Solvay, Belgium)
as a typical compound used as oxygen source; modified calcium peroxide – 1:1
mixture of calcium hydroxide oxide and calcium peroxide (ORC Advanced
® and
ORC
® Primer, Regenesis, USA) that should provide oxygen release in longer term;
and gelatinous hydrogen peroxide (OXYGEL, Biorem, Belgium) which slowly
releases hydrogen peroxide from the gel matrix. The oxygen release materials were
injected directly into the probes (injection flowrate and pressure 30 L/min, 6–20 bar,
respectively). Four to five injection horizons per probe were performed on the basis
of the MIP profile from the nearby MIP probe. An example of the targeted injection
scheme based on the MIP profile is shown in Fig. 19.1.
The materials, regardless of their actual chemical structure, were injected at the
amount capable of releasing 17 kg of O 2 per borehole. In case of calcium peroxide
and modified calcium peroxide, this means that 100 kg of material diluted in 500 L
of water taken from the aerated bioreactor used within the pump-and-treat technology installed further on site was injected per one injection point. Gelatinous hydrogen peroxide contains 10.6% of releasable oxygen and therefore 160 kg of the
product mixed with 140 L of water taken from the aerated bioreactor was injected
per one injection point.
Mixing water from the aerated bioreactor contained significant numbers of
bacteria capable of aerobic biodegradation, although these bacteria were probably
significantly inhibited by the high pH of the suspensions (and presence of hydrogen
peroxide), some might have survived and later helped to enhance biodegradation of
target contaminants. The scheme of the field study layout is displayed in Fig. 19.2.
The distance between the injection points and the monitoring well was approximately 1.5 m. MIP and soil monitoring probes were approximately 0.75 m far from
the monitoring well.
MIP and soil monitoring probes were performed prior to the injection and the
holes were sealed by cement afterwards.
19 Field Study VII: Field Study of Three Different Injectable. . .
413