The 3 rd International conference on Sustainable Remediation. Case Studies

Transcription

1 The 3 rd International conference on Sustainable Remediation Case Studies Eco-efficient Risk Management of a Creosote Contaminated Site Pirjo Tuomi (PhD, Golder Associates, Finland) Hannu Hautakangas (MSc, Golder Associates, Finland) Heikki Laakso (MSc, Golder Associates, Finland) Antti Kari (MSc, Senate Properties, Finland)

2 The Site Creosote impregnation of railroad ties between 1947 and 1958 Photo: Not from the Site Photo: Creosote contaminated soil at the Site ottobre 15,

3 The Site n Forested and sparsely populated area. Hot spot Top soil contamination Rail road Vadose soil contamination Possibly DNAPL Dissolved plume ottobre 15, House hold wells

4 The Site Top soil contamination Rail road Clay/silt Clay/silt Bed rock DNAPL ottobre 15,

5 The Site Currently, biggest load of dissolved contaminants to GW takes place from saturated zone, not vadose zone Top soil contamination Rail road Clay/silt Clay/silt Bed rock ottobre 15,

6 Risks 1. High concentrations in surface soil (dust, mushrooms, berries) 2. Groundwater use, nearest private wells 3. Plume increasing? Clay/silt Clay/silt Bed rock ottobre 15,

7 Site Wide Risk Management 1. Surface soil: Remediation - Covering - Excavation - Phytoremediation 2. Groundwater use: New uptake well in safe area 3. Plume: a) Studying stability b) Comparing treatment options Clay/silt Clay/silt Bed rock ottobre 15,

8 GoldSET Approach Structured process based on multi-criteria decision analysis Project Description Option Development Indicator Selection Evaluation of Options Interpretation & Decision Making Describe project context & objectives Define range of project options (representative alternatives) Engage influencers & subject matter experts Evaluate risks & opportunities Define decision criteria & indicators Study alternatives Rank and score based on criteria / indicators 8

9 Saturated zone/plume management option listing All remedial options listed Free/residual phase management/removal Dissolved plume 25 different options (from natural attenuation to excavation) Brief description how each option could be applied at the site 13 out of 25 options was discarded as not at all feasible The options selected to further consideration focus on managing or removing DNAPL as there is no point in treating dissolved plume untill the DNAPL is managed 12 out of 25 included significant uncertainties and were likely expensive In order to pick out options for the GoldSET evaluation, rough cost estimates were done ottobre 15,

10 Saturated zone/plume management option screening Large range in cost estimates none of the options were designed in detail Total cost, m eur Option min max Excavation GW flow management (P&T) 2 8 Free phase recovery wells 1 3 Belt skimmers 1 3 Thermal treatment (+ free phase recovery) 4 42 Containment using sheet piles (+ free phase recovery) 1 4 Containment using jet grouting (+ free phase recovery) 3 11 Containment using Cast- in- place pile (+ free phase recovery) 3 10 Soil flushing 6 13 ISCO 3 23 ISGS 1 9 Monitoring stabile plume 0,3 1 ottobre 15,

11 Option descriptions n Free phase recovery wells n n Free phase removal for 5-10 years Monitoring for years Hot spot Top soil contamination Rail road Vadose soil contamination Possibly DNAPL Dissolved plume 11 11

12 Option descriptions n Sheet pile barrier and free phase recovery wells n n n Ground water level management Free phase removal Monitoring for 50 years Hot spot Top soil contamination Rail road Vadose soil contamination Possibly DNAPL Dissolved plume ottobre 15,

13 Option descriptions Excavation Source partly excavated (railroad) Excavation 1-2 years Monitoring years 10 m 10 m ottobre 15,

14 Option descriptions n Monitoring n n Plume stabile Monitoring for 50 years, not until the site is clean (which can take centuries) Hot spot Top soil contamination Rail road Vadose soil contamination Possibly DNAPL Dissolved plume ottobre 15,

15 GoldSET Indicator Selection Environmental impacts Ecology, greenhouse gas emission, energy consumption, use of natural resources, contaminant destruction, waste production, improvement of groundwater quality, improvement of soil quality Social impacts General disturbance, noice, dust, health impact, local employment, local business opportunities Economical effects Option cost, reuse of the property Technical aspects Flexibility, reliability ottobre 15,

16 Indicator weighting Ecological Impacts Resulting from the Project -> 1 Site not sensitive, ecological issues not important. Soil Quality (vadose and saturated) -> 2 Improvement of soil quality is not a primary goal Groundwater Quality -> 3 The free product removal and prevention of waterborne contaminant migration are the most important environmental aspects to be considered. ottobre 15,

17 Options evaluation Quantative indicators Greenhouse gas emissions: ottobre 15,

18 Options evaluation Qualitative indicators Flexibility of the technology Assesses the level of effort required for expansion, potential optimization over time and accommodating changes in operation Scoring Scheme : 0 = Very limited adaptive capacity with significant constrains/ restrictions; significant efforts required. 33 = Limited adaptive capacity with major constrains/restrictions; major efforts required. 66 = Moderate adaptive capacity with some constrains/restrictions; moderate efforts required. 100 = Adaptive capacity is built into the system; minimal or no efforts anticipated. ottobre 15,

19 Interpretation Excavation proven technology, but has significant negative environmental impacts and is clearly most expensive Free phase recovery wells and monitoring stable plume scored well in all aspects, but they do have technical uncertainties Confinement economically good, but otherwise not scored well ottobre 15,

20 Interpretation - Environment Effect on site ecology Air quality Improvement of soil quality Use of natural resources Improvement of GW quality No improvement Waste formation ottobre 15,

21 Conclusions Eco-efficiency evaluation Transparency - why certain options are favoured Including sustainability in the descision process during the early stages of designing Demonstrate negative impacts that are often ignored in descision process Multi-criteria analysis Taking into account Both qualitative and quantitative criteria Criteria in different units ottobre 15,

22 Thank you! Contact: ottobre 15,