Thursday, July 7, 2016

Quantifying Global Impacts to Society from the Consumption of Natural Resources during Environmental Remediation Activities

Environmental remediation activities often require the management of large volumes of water and the consumption of significant amounts of local natural resources, including energy and fossil fuels. Traditionally, proposed remedial approaches for a specific cleanup scenario are evaluated by overall project implementation cost, time frame of the cleanup, and effectiveness to meet cleanup goals. A new paradigm shift, referred to as sustainable remediation, has influenced the remediation industry to consider environmental, social, and economic impacts from cleanup activities. An environmental footprint analysis is the most common method to evaluate environmental implications of cleanup approaches. Presently, these footprint tools do not associate the environmental implications with global impacts. In this article, the method has been extended to integrate the social cost of carbon emissions to quantify global impacts. The case study site is a former aircraft parts manufacturing facility that caused chlorinated solvent contamination in soil and groundwater beneath the building. A groundwater pump-and-treat system was initially installed, followed by its gradual phase-out with concurrent phase in of in situ bioremediation. The case study evaluates the monetized societal benefits from quantifying carbon emission impacts of the proposed cleanup approaches and alternative scenarios. Our results suggest that societal impacts based on monetized carbon emissions can be reduced by 27% by optimizing the remediation processes. The sensitivity analysis results elucidate how variation in carbon prices and social discount rates can influence cleanup decisions for remediation projects.
The social cost of an environmental metric links local consumption of natural resources to monetized global impacts. As shown in table 1, the costs borne by society, represented by the social costs of CO2-eq and noncarbon emissions from electricity generation, decreased over time by phasing out the P&T system and incorporating bioremediation. The cumulative social cost calculated using a 2.5% discount rate is $29,894.67 for scenario I and $21,792.59 for scenario II, a difference of $8,102.08 (i.e., an overall 27% reduction in monetized global impacts).
To put the costs borne by society from remedial activities into a broader context, the monetized global impacts calculated for scenarios I and II at a 2.5% discount rate were used to predict the costs society may bear from cleaning up the remaining hazardous waste sites in the United States. The US EPA projected that a total of 169,000 hazardous waste sites will require cleanup between 2004 and 2033, excluding small underground storage tank sites (US EPA 2012b). These site cleanups vary dramatically owing to the size of the property and the amount of time required to remove and/or contain the contamination. The case study site is relatively small compared to a typical remediation project. In order to use the case study site as a broad representation of typical cleanup sites, the costs borne by society (using a 2.5% discount rate) from scenarios I and II was scaled up fivefold to get a lower and tenfold to get a higher range for an average per-site social cost of remedial activities. Thus, the rough average per-site social cost of remediation might be:

    Scenario I: $150,000 to $300,000
    Scenario II: $110,000 to $220,000

Estimated remediation-related social costs for the remaining 169,000 hazardous waste sites would range between $19 billion and $51 billion. This calculation illustrates that CO2-eq emissions from the local consumption of resources as part of remedial activities over an extended period of time has the potential to be a significant contributor to monetized global impacts.
Choosing an Appropriate Discount Rate
Fig. 7-6: Bioventing System Using Vapor Extraction. Source: EPA
Table 1 shows the costs borne by society for each remedial scenario using various discount rates for the USG social cost of carbon. The discount rate can have a significant effect on the calculated social costs (i.e., monetized global impact). In 2014 U.S. dollars, the difference between the monetized global impacts from the P&T system over the life cycle of the remedial process, using 2.5% and 5% social cost of carbon discounts rates, is $23,985.21. This substantial difference highlights the importance in understanding and incorporating the appropriate discount rate in an SCBA.

By considering a lower discount rate in an SCBA, more weight is placed on long-term, intergenerational impacts. This is simply illustrated by the calculated social costs using a 5% discount rate ($4,089.53 to $5,195.05) (table 2) and with a 2.5% discount rate ($21,267.17 to $29,369.26) (table 2). Then compare the market value of CO2-eq ($749.63 to $6,168.44) (table 2). The higher discount rate places more weight on short-term impacts, and therefore the costs borne by society using the USG social cost of CO2 at a 5% discount rate is closer in value with the total market value of CO2-eq than the social cost of CO2 at 2.5% discount rate. The social cost of carbon at a 2.5% discount rate is more representative of increases in the social cost of carbon over time, because future emissions are expected to produce larger incremental damages as physical and economic systems become more stressed in the response to worsening climate change over time (USG 2013).
Social Cost vs. Market Price of Carbon Dioxide Evaluation

Table 2 presents the monetized global damages of CO2-eq for each remedial scenario, using the USG social cost of carbon at 2.5% and 5% discount rates and several market prices of CO2. In 2009, the social cost of carbon for replacing P&T with bioremediation ($270.10, USG 2.5% discount rate) is less than the total market price of CO2 for maintaining the P&T system for three of the four carbon price regimes ($410.91 to $472.55) This analysis shows that the monetized global impacts of the reduced-footprint remedial system eventually became lower than the cost of the old system. Social planners and remediation decision makers could use this comparative analysis to set sustainability goals for system optimization.

The total market value of CO2 using the RGGI carbon price ranged from $749.63 to $1,034.95. The average total market value of CO2 of the three other carbon price regimes (California GHG Cap-and-Trade, Quebec's Carbon Market, and Synapse) ranged from $4,078.932 to $5,632.65. The difference in the total market value between RGGI and an average of three other carbon regimes is 82%. Each carbon regime is representative of a specific geographical region, and the associated carbon price for each regime is influenced by regional policy, sustainability objects, and stakeholder input. As stated earlier, there is no absolute market for carbon. Therefore, careful consideration should be taken in identifying a representative market price of carbon to use for a cost benefit analysis (CBA). The market price used for the analysis should be representative of the site's geographical location and the stakeholder's sustainability objectives.

The cumulative total market price of CO2-eq (in 2014 U.S. dollars) for scenario I ranged from $1,034.95 to $6,168.44; and for scenario II, it ranged from $749.63 to $4,466.92. The long-term potential benefits from reducing the cumulative market cost of CO2 for a specific project can include a reduction in the required emission credits to be purchased for operating the system, and the affordability to use “saved” CO2 emission credits to install a system at another cleanup site.
Water Footprint

The literature search did not find a representative social cost of water to include in the cost borne by society calculations. Therefore, the monetized global impacts for each remedial scenario are underestimated owing to this missing information.

We found that the amount of water consumed (figure 3) was substantially decreased, and ultimately reduced to zero, by phasing out the P&T system and phasing in bioremediation. This decreasing trend parallels the reduction in costs borne by society from enhancing the remedial approach at the case study site. This aspect of reducing local consumption is of particular global importance in regions that are water stressed. The Sustainable Remediation Forum (SURF) recently published guidance on implementing groundwater conservation and reuse practices at remediation sites (SURF 2013). In alignment with SURF's Guidance, this case study shows the benefits from implementing groundwater conservation practices by transforming the remedial action from an ex situ remedy (i.e., removing contaminated media from the subsurface) to an in situ remedy (i.e., treating contaminated media in place).
by Melissa A. Harclerode*, Pankaj Lal and Michael E. Miller
Journal of Industrial Ecology via Yale University
Special Issue: Linking Local Consumption to Global Impacts
Volume 20, Issue 3, pages 410–422, June 2016
Keywords: environmental footprint analysis;industrial ecology;social cost benefit analysis;social cost of carbon;socioeconomic impacts;sustainable remediation

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