285
Permeable Reactive Barriers in Europe
was below 30 mg/L. The groundwater exhibited very high carbonate hardness due to the abundant red and shelly limestone in the area. Sulfate levels
were determined at 200 mg/L. The low hydraulic gradient of 2% prompted
to design a full-scale D&G PRB that catches (collects) and drains the contaminated groundwater passively by means of a 90-m-long gravel drain
equipped with additional filter pipes. The drain directs the groundwater
toward a reactor loaded with GAC. The depth of the PRB is about 6 m. The
Denkendorf D&G reactor was constructed as a shaft-shaped structure (ISV)
employing standard civil-engineering techniques. The system meets its
remediation goal of 10 μg/L cVOCs.
A bypass from the passively drained groundwater flow into the reactor
was installed to test innovative reactive materials such as palladium on zeolite (palladium loading: 0.5% (w/w)) directly inside the shaft under field conditions. Investigations were implemented by a member project of the RUBIN
R&D program (Burmeier et al., 2006). The catalyst had a “molecular design”
(due to its “zeolite back bone” wherein the palladium was finely dispersed
in three-dimensional (3D), molecular canals). This design was supposed to
prevent sulfides from poisoning the palladium, being a frequent, serious
problem when palladium is used in contaminated groundwater comprising
relatively high sulfate concentrations (Birke et al., 2003, 2007; Parbs and Birke,
2005). Different other designs and types of catalysts had also been successfully tested using the bypass at the D&G PRB between 2007 and 2012 (Birke
and Burmeier, 2012a,b).
13.2.2.4 Edenkoben
Set up in 1998 (pilot scale), extended to full scale in 2000. Type: F&G (six
gates), restricted accessibility to the gates, ZVI for cVOC degradation. For
detailed design features, see Rochmes and Woll (1998), Rochmes (2000), and
Birke et al. (2003).
A groundwater contamination by cVOCs at Edenkoben was attributed to
the former use of CHC solvents for production processes on-site. Several hot
spots were found on the property, partly situated below some buildings. A
heterogeneous cVOC plume that was more than 400 m wide, originating by at
least three individual, partly overlapping plumes, was identified. These individual plumes contained different contaminants at varying concentrations.
For example, the southern plume chiefly consisted of TCE and cis-DCE to a
total of 8000 μg/L cVOCs. The middle plume comprised 1,1,1-TCA, TCE, and
cis-DCE (up to 20,000 μg/L cVOCs), whereas the northern plume was contaminated predominantly by PCE (≈ 2000 μg/L cVOCs). The average composition of cVOCs was 20% TCE, 50% cis-DCE, and 30% 1,1,1-TCA. The geology
was characterized by infills and a highly heterogeneous sedimentology (silty
overlying strata, 1–6 m thick). Two relevant aquifers had to be taken into
account, the lower aquifer being nonpolluted. The polluted upper aquifer was
split into two permeable layers, separated by silt and silt–sand strata varying
Permeable Reactive Barriers in Europe
was below 30 mg/L. The groundwater exhibited very high carbonate hardness due to the abundant red and shelly limestone in the area. Sulfate levels
were determined at 200 mg/L. The low hydraulic gradient of 2% prompted
to design a full-scale D&G PRB that catches (collects) and drains the contaminated groundwater passively by means of a 90-m-long gravel drain
equipped with additional filter pipes. The drain directs the groundwater
toward a reactor loaded with GAC. The depth of the PRB is about 6 m. The
Denkendorf D&G reactor was constructed as a shaft-shaped structure (ISV)
employing standard civil-engineering techniques. The system meets its
remediation goal of 10 μg/L cVOCs.
A bypass from the passively drained groundwater flow into the reactor
was installed to test innovative reactive materials such as palladium on zeolite (palladium loading: 0.5% (w/w)) directly inside the shaft under field conditions. Investigations were implemented by a member project of the RUBIN
R&D program (Burmeier et al., 2006). The catalyst had a “molecular design”
(due to its “zeolite back bone” wherein the palladium was finely dispersed
in three-dimensional (3D), molecular canals). This design was supposed to
prevent sulfides from poisoning the palladium, being a frequent, serious
problem when palladium is used in contaminated groundwater comprising
relatively high sulfate concentrations (Birke et al., 2003, 2007; Parbs and Birke,
2005). Different other designs and types of catalysts had also been successfully tested using the bypass at the D&G PRB between 2007 and 2012 (Birke
and Burmeier, 2012a,b).
13.2.2.4 Edenkoben
Set up in 1998 (pilot scale), extended to full scale in 2000. Type: F&G (six
gates), restricted accessibility to the gates, ZVI for cVOC degradation. For
detailed design features, see Rochmes and Woll (1998), Rochmes (2000), and
Birke et al. (2003).
A groundwater contamination by cVOCs at Edenkoben was attributed to
the former use of CHC solvents for production processes on-site. Several hot
spots were found on the property, partly situated below some buildings. A
heterogeneous cVOC plume that was more than 400 m wide, originating by at
least three individual, partly overlapping plumes, was identified. These individual plumes contained different contaminants at varying concentrations.
For example, the southern plume chiefly consisted of TCE and cis-DCE to a
total of 8000 μg/L cVOCs. The middle plume comprised 1,1,1-TCA, TCE, and
cis-DCE (up to 20,000 μg/L cVOCs), whereas the northern plume was contaminated predominantly by PCE (≈ 2000 μg/L cVOCs). The average composition of cVOCs was 20% TCE, 50% cis-DCE, and 30% 1,1,1-TCA. The geology
was characterized by infills and a highly heterogeneous sedimentology (silty
overlying strata, 1–6 m thick). Two relevant aquifers had to be taken into
account, the lower aquifer being nonpolluted. The polluted upper aquifer was
split into two permeable layers, separated by silt and silt–sand strata varying