Environmental Engineering Reference
In-Depth Information
11.6.3.1 Case Study For a Benzene-Contaminated Site
A benzene spill occurred along the highway near a small town of 1600 residents follow-
ing a train derailment, resulting in the leaching of a certain amount of benzene into the
groundwater aquifer used by the residents for their domestic well water. The area of the
affected site was 6 ha. Since the concentration of benzene in the groundwater was 55 μg/L,
this needed to be reduced to the maximum allowable contaminant level (MCL) of 5 μg/L
for drinking water. The software was used for comparison of remediation options for ben-
zene contaminated groundwater at the given site. Identiied options included:
• Pump and treat followed by activated carbon treatment of the groundwater
• Pump and treat and followed by air stripping of the groundwater
• Biosparging and soil vapor extraction (SVE)
• Monitored natural attenuation
Table 11.4 provides a list of the indicators used for the analysis. Weights (1-3) were assigned
to each indicator listed in Table 11.4. Although a life cycle assessment is not performed by
the software, the indicators should be designed to consider the changing technological and
environmental conditions and at different stages in the process. Results showed that, with
respect to the environment, natural attenuation and biosparging and SVE appear to be more
appropriate for this site. They appear to have minimum impact on soil quality and on fauna
and lora resulting from the project, soil vapor intrusion, greenhouse gas emissions, energy
consumption, and quantity of wastes. Meanwhile, activated carbon and air stripping seem
to be less appropriate because of the disturbance to the natural condition of the site due
to excavation and groundwater extraction, higher energy consumption due to pumping of
groundwater, and higher production of greenhouse gases due to the heavy trucks usage.
Activated carbon and air stripping have the highest initial costs, whereas natural atten-
uation and biosparging have higher monitoring costs. However, the selection of natural
attenuation may require additional institutional controls to adhere to local regulations and
TABLE 11.4
List of Selected Sustainability Indicators Considered for the Analysis
Type of Indicator
Environmental Aspects
Economic Aspects
Social Aspects
Soil quality
Sediment quality
Contaminated soil erosion
Groundwater quality
Free product
Surface water quality
Waterborne contaminant migration
Water usage
Impact on fauna during project
Impact on fauna after project
Soil vapor intrusion
Greenhouse gas emissions
Energy consumption
Quantity of wastes
Hazardous wastes
Residual impact of technology
NPV of option costs
Potential litigation
Financial recoveries
Environmental reserve
Standards, laws, and regulations
Service reliability and
performance
Reuse of the property
Corporate image
Reliability
Technological uncertainty
Logistics
Community health and safety
Worker's health and safety
Drinking water supply
Direct local employment
Opportunities for local business
generation
Public disruption
Quality of life
Public use
Cultural heritage
Impact on the landscape
Management practices
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