Remediation of gas stations: sustainability assessment of Excavation and removal of contaminated soil (Tools, Metrics and Indicators)

Transcription

1 The 3 rd International conference on Sustainable Remediation Remediation of gas stations: sustainability assessment of Excavation and removal of contaminated soil (Tools, Metrics and Indicators) Lanari C., Ambrosini P., Patata L., Crimi G., Ragni P., Schillaci P. Saipem spa, via Toniolo, 1 Fano (PU)

2 Agenda Ø Vadose zone remediation technologies Ø Applicability of excavation and removal of contaminated soil Ø Case-study Ø LCA evaluation (methodology and results) Ø Conclusions

3 Vadose zone remediation technologies How to select Technologies for soil remediation in vadose zone? Current regolations reference: D.Lgs. 152/06 Potentially applicable Technologies for remediation must refer to the following criteria: protection of both environment and human health achievement of remedial objectives long and short-term effectiveness ease of implementation and management minimal environmental impact economic aspects degree and extent of contamination recommendation of public autorities

4 Vadose zone remediation technologies Gas stations characterized by: limited operational area limited time of operation limited invasiveness required contamination from refinery products such gasoline and diesel site rebuilding, in this case remediation by excavation could take place simultaneously with rebuilding activities Preference is given to technologies of proven effectiveness, applied extensively in numerous situations Which Technologies are used frequently for soil remediation in vadose zone?

5 Vadose zone remediation technologies Soil Vapor Extraction (SVE) / Bioventing (BV) Multi Phase Extraction (MPE) Rif: US-EPA, 1995 Excavation and transport to disposal or reuse after treatment Rif: Schema del sistema di TPE (Da: US-EPA, 1997) Bioremediation (BIOPILE)

6 Applicability of excavation and removal of contaminated soil When this approach is preferred compared to other remedial Technologies? 0 Excavation is not allowed Gas service station: CLOSED SITE 1 Limited extension of the remediation area 2 Need to restitute the area within a short period of time 3 High concentrations in the soil compared to remediation goals 4 Soil with low permeability or high degree of heterogeneity 5 Low depth of contamination

7 Applicability of excavation and removal of contaminated soil Gas service station: OPERATING SITE (...) ( ) Presence of structures and/or substructures hindering the excavation Impossibility of interrupting commercial activity for the time required to remove contaminated soil Site rebuilding (in this case remediation by excavation could take place simultaneously with the rebuilding activities)

8 Case-study 1 CLOSED SITE (small-sized intervention), some information Remove of all structures above- and below -ground Groundwater table between 9 and 14 m below g.l. Hydrocarbon contamination at 4 m below g.l. = mg/kg CSR (Remedial objectives) for Hydrocarbon = 3808 mg/kg Contamination area = 30 m2 Selected applicable technologies Excavation with sheet piles and transport to disposal Excavation without sheet piles and transport to disposal Soil Vapor Extraction (SVE) / Bioventing (BV)

9 Case-study 1 Excavation with/without sheet piles and transport to disposal ACTIVITIES Installation of temporary retaining walls in the excavation Soil excavation Soil storage in the site (include preparation of the area) Soil disposal Monitoring, refilling and area restoration VEHICLES, MATERIAL AND ENERGY Sheet piles, pile-driver, truck Excavator, Loader, Truck Geotextile, Backfill, HDPE, LDPE Excavator, Truck Truck, landfill Quarry material, Truck, Excavator, automobile

10 Case-study 1 Excavation with sheet piles and transport to disposal MAX EXCAVATION DEPTH (m below g.l.) VOLUME OF SOIL TO BE EXCAVATED (m 3 ) VOLUME OF CONTAMINATED SOIL TO DISPOSAL (m 3 ) VOLUME OF NON CONTAMINATED SOIL FOR REUSE DIRECTLY ON SITE (m 3 ) weeks

11 Case-study 1 Excavation without sheet piles and transport to disposal MAX EXCAVATION DEPTH (m below g.l.) VOLUME OF SOIL TO BE EXCAVATED (m 3 ) VOLUME OF SOIL TO DISPOSAL (m 3 ) VOLUME OF SOIL FOR REUSE DIRECTLY ON SITE (m 3 ) weeks

12 Case-study 1 Soil Vapor Extraction (SVE) / Bioventing (BV) ACTIVITIES Piezometers Suction Interconnecting Gas treatment Monitoring and inspection soil after treatment VEHICLES, MATERIAL AND ENERGY PVC, Filter pack, Cement, Bentonite Truck, Drilling machine, Landfill Blower, Truck Mini-excavator, Loader, HDPE, Steel, Truck, Landfill Condensate separator, Transfer pump, Tank, GAC Filters, Truck, Landfill Cement, Bentonite, Truck, Drilling machine, automobile 18 monthssve + 6 months BV

13 Case-study 2 CLOSED SITE (avereged-sized intervention), some information Removal of all structures above- and below -ground Water table between 4 and 6 m below g.l. Hydrocarbon and BTEX soil contamination at buried tanks level Hydrocarbon, BTEX and MTBE contamination in groundwater Contamination area = 1260 m2 Selected applicable Technologies Excavation and transport to disposal Excavation and reuse after treatment (BIOPILE) Multi Phase Extraction (MPE)

14 Case-study 2 Soil excavation ACTIVITIES Soil storage in the site (include preparation of the area) Soil disposal Monitoring, refilling and area restoration Excavation and transport to disposal VEHICLES, MATERIAL AND ENERGY Excavator, Loader, Truck Suction Pump, Storage tank Backfill, HDPE, New jersey, LDPE, Excavator, Truck Truck, Landfill Quarry material, Truck, Excavator, Automobile

15 Case-study 2 Excavation and transport to disposal MAX EXCAVATION DEPTH (m below g.l.) VOLUME OF SOIL TO BE EXCAVATED (m 3 ) VOLUME OF CONTAMINATED SOIL TO DISPOSAL (m 3 ) VOLUME OF NON CONTAMINATED SOIL FOR REUSE DIRECTLY ON SITE (m 3 ) months

16 Case-study 2 Excavation and reuse after treatment (BIOPILE) BIOPILE ACTIVITIES Soil transport and unloading Soil movement Soil sieving Pile construction Pile humidification Pile oxygenation Pile dismantling Soil transport to reuse Truck VEHICLES, MATERIAL AND ENERGY Backhoe Sieving system PE pipes coated with coconut fiber, Loader Water solution Blower Backhoe Truck 2 3 months

17 Case-study 2 ACTIVITIES Piezometers Suction Interconnecting Gas treatment Water treatment Monitoring and site close after treatment Multi Phase Extraction (MPE) VEHICLES, MATERIAL AND ENERGY PVC, Filter pack, Cement, Bentonite Truck, Drilling machine, Landfil High-vacuum pump, Phase separator, Transfer pump, Tank, Truck Mini-excavator, Loader, HDPE, Truck, Landfill GAC Filters, Truck, Landfill GAC Filters, Truck, Landfill Cement, Bentonite, Truck, Drilling machine, Landfill, automobile 36 months

18 LCA (methodology and results) What is LCA Life Cycle Assessment is a quantitative technique for assessing the environmental aspects associated with a product or system or process over its life cycle, standardized by ISO of series. identifying opportunities to improve the environmental performance of products at various points in their life cycle. support decision-makers in industry, government and other bodies (e.g. for the purpose of strategic planning, priority setting, product or process design) marketing and procurement (e.g. green procurement, implementing an ecolabelling scheme, making an environmental claim, or product declaration

19 LCA (methodology and results) How LCA works Goal and scope definition Intended application, audience, product system, functional unit, data required, system boundary, limitations. Inventory analysis Energy and material inputs. Products, coproducts and waste. Emissions to air water and soil Impact assessment Impact categories, indicators and characterization models, Results Interpretation Findings are considered together and consistent with scope and goal

20 LCA (methodology and results) Preliminary comparison of remediation technologies in two case studies The functional unit is 1m3 of contaminated soil Data quality: project data Goal and Scope Inventory Simapro V7.3.3 Ecoinvent V2.2 Impact Assessment IPCC 2007 GWP 100 ReCiPe endpoint (H)

21 LCA (methodology and results) LCA Case study-1 IPCC 2007 GWP:characterization The least impacting technology is excavation and disposal with sheet piles because, compared to the solution without sheet piles, the volume of soil to be excavated and transported to the disposal site is substantially reduced. The GWP is equal to 974 kg CO2eq, about one third of the highest impacting solution The SVE technology generates a high global warming potential, similar to that determined by excavation and disposal without sheet piles.

22 LCA (methodology and results) LCA Case study-1 IPCC 2007 GWP:contribution analysis Contribution analysis shows the environmental impact of single processes For all technologies the processes with the highest impact are those tied to the consumption of fuel for motors or for energy production

23 LCA (methodology and results) LCA Case study-2 IPCC 2007 GWP:characterization The least impacting technology is MPE: 124 kg CO2eq/m3. The difference among technologies for this application is limited. In terms of GWP the benefit of reusing decontaminated soil is low. The amount of CO2eq emitted is much lower than in case study C1, both for a scale factor and because the contaminated soil is more confined. Consequently the relationship between moved and decontaminated soil is minor.

24 LCA (methodology and results) LCA Case study-2 IPCC 2007 GWP:contribution analysis Contribution analysis shows the environmental impact of single processes Transport is the process with the highest impact in the excavation and disposal technology. For MPE the greatest emissions are determined by the consumption of electric energy

25 LCA (methodology and results) LCA Case study-1 ReCiPe 2008 (H) H/ H damage assessment and normalization Normalization Damage assessment Even with ReCiPe, excavation and disposal with sheet piles is the least impacting technology (same result obtained with IPCC method). The highest impacting technology is excavation and disposal without sheet piles. The SVE technology presents intermediate impact.

26 LCA (methodology and results) LCA Case study-2 ReCiPe 2008 (H) H/ H damage assessment and normalization Normalization Damage assessment The results obtained using the ReCiPe model are similar to those of the IPCC model. The least impacting technology is MPE, but the difference among the three technologies is neglectable.

27 Conclusions In some cases, excavation and removal of contaminated soil is necessary (the best technology): need to restitute the area in a short period of time; high concentrations in the soil compared to remediation goals; site rebuilding (remediation by excavating contaminated soil could take place simultaneously with the rebuilding activities). Based on the results of LCA Case-study 1 (IPCC 2007 and ReCiPe 2008), the excavation and removal technology is less impacting than SVE.

28 Conclusions The results obtained with LCA Case-study 2 (IPCC 2007 and ReCiPe 2008) showed that the technology with the lowest impact is MPE, although the difference with excavation and removal is minor. Reuse of decontaminated soil (with BIOPILE treatment ex situ) produces a lower benefit compared to disposal in a landfill. With reference to MPE and SVE technologies, based on the contribution analysis we can conclude that the highest impact is caused by the electric power needed to charge the systems. Therefore, it could be both interesting and convenient to use machinery with highly efficient electric motors and limited consumption, or renewable energy.

29 thanks / authors details We wish to thank Paolo Ricci and Euro Buongarzone for their collaboration (FAPLEN Department, Saipem spa) Paolo Ambrosini paolo.ambrosini@saipem.com