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On-Site Treatment of a Dissolved Chromium Plume: From Bench Trial to Remediation to Results
Barry Rakewich, P.Ag., EP Kyle Jackson, C.E.T. Nichols Environmental (Canada) Ltd.
From Bench Trial to Remediation to Results Barry Rakewich, P.Ag., - - PowerPoint PPT Presentation
From Bench Trial to Remediation to Results Barry Rakewich, P.Ag., - - PowerPoint PPT Presentation
On-Site Treatment of a Dissolved Chromium Plume: From Bench Trial to Remediation to Results Barry Rakewich, P.Ag., EP Kyle Jackson, C.E.T. Nichols Environmental (Canada) Ltd. Outline Site History Phase II ESA Bench Trial
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Site History
September 2003 Environmental Review Completed June and July 2009 Violations of Sewer Use Bylaw April 2011 Phase I ESA June to Dec 2011 Phase II ESA 29 MWs July to Sep. 2012 Pump and Treat Installation September 2012 In Situ Chemical Reduction February 2012 Phase II ESA 3 MWs September 2012 Initiate Pump and Treatment August 2013 In Situ Chemical Reduction October 2015 End of Pump and Treatment September 2017 Most Recent GW Sampling September 2012 Bench Trial
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Site Layout
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Phase II ESA
Completed numerous Phase II ESAs to
gain delineation
June 2011 (M11-01 to M11-06) July/August 2011 (M11-07 to M11-16) Nov/Dec 2011 (M11-17 to M11-29) Feb 2012 (M12-30 to M12-32)
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Phase II ESA – June 2011
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Phase II ESA – July/Aug 2011
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Phase II ESA – Nov/Dec 2011
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Phase II ESA – Feb 2012
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Phase II ESA
Assessment Criteria
Alberta Tier 2 Soil and Groundwater Remediation Guidelines (February 2016) Site zoned Medium Industrial (IM); also permits commercial land use
Commercial Land Use
Subsoils predominately silty-clay and were confirmed through sieve analyses
Fine-Grained Soils
Surface water retention pond (~1.1 km)
Exclude the protection freshwater aquatic life (FWAL) pathway
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Phase II ESA
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Phase II ESA
Pre-Treatment Chromium Concentrations
- 0.05
M11-01 Jul-11 0.0638 0.059 M11-02 Aug-11 0.6620 0.149 M11-03 Aug-11 4.15 4.1 M11-05 Aug-11 308 300 M11-14 Nov-11 20.3 19.7 M11-22 Dec-11 70.1 63
BOLD = Applicable Guideline Criteria BOLD = Parameter Exceeds Recommended Guideline Criteria *Alberta Tier 2 Soil and Groundwater Remediation Guidelines (Table 2). February 2016. (All concentrations in mg/L = ppm, unless noted)
- -- = No value provided in guidelines
Hexavalent Chromium Alberta Tier 2 Guideline (Commerical Land Use)* Sample ID Total Chromium Sample Date
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Phase II ESA
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Bench Trial
Ferrous Sulphate (FeSO4) Sodium Metabisulphite (Na2S2O5) Readily Available Readily Available Solubility - 29.51 g/100 mL (25 °C) Solubility - 67 g/100 mL (25 °C) pH adjustment not required Effectiveness highly pH dependent Presence of iron produces rapid flocculation Production of SO2 by-product can be an irritant ½ cost of sodium metabisulphite per Highly corrosive when mixed with water
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Bench Trial
Ferrous Sulphate (FeSO4) Sodium Metabisulphite (Na2S2O5) 30 mg/L 25 mg/L 99% Reduction of Cr6+ after 5 mins 53% Reduction of Cr6+ after 5 mins Rapid flocculation/settling Marginal flocculation/settling
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Remediation Design
Pump and Treatment
Focus on high concentration plume Large diameter bored wells w/submersible pumps installed in ‘hot spots’ Treatment/settling tanks w/secondary containment Filter pot discharge to sanitary
In-Situ Chemical Reduction (ISCR)
Focus on low concentration plume and Site boundaries Entire site surfaced with concrete Established network of pre-cored injection points High-pressure direct injections at GW interface
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Pump and Treatment
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Pump and Treatment
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Pump and Treatment
Installed 3 – 60 cm diameter recovery wells
Recovery wells consisted of galvanized CSP (resulted in dissolved zinc in GW)
Submersible pumps (3.5 HP) installed into each of the three wells, capable of 5 gpm.
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Pump and Treatment
On-site treatment plant consisting of two – 20,000 L ASTs
Secondary containment system
Sample ports and filter pot prior to discharge
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Pump and Treatment
Groundwater Recovery – Volume in Litres
2012 (September to November) 17,800 2013 (March to November) 119,300 2014 (May to October) 85,000 2015 (May to October) 112,600
Total 334,700
Average Batch Volume = 7,500 L treated with 35 kg of FeSO4 ~1550 kg of FeSO4 utilized during treatment process
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Pump and Treatment
Operation and Maintenance Costs
2012 (installation) $75,000 2012 (operational) $15,000 2013 (operational) $30,000 2014 (operational) $33,000 2015 (operational) $31,000
Total Costs $184,000
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Pump and Treatment
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ISCR
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ISCR
Injection Summary – Volume in Litres
15% Ferrous Sulphate
September 2012 1,000 August 2013 7,900 July 2015 12,000
Total 20,900
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ISCR
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Results
Post-Treatment Chromium Concentrations
- 0.05
Jul-11 0.0638 0.059 Sep-17 0.0306 <0.01 Aug-11 0.6620 0.149 Apr-17 0.0120 <0.01 Aug-11 4.15 4.1 Sep-15 0.0055 <0.01 Aug-11 308 300 Sep-17 0.193 0.01 Nov-11 20.3 19.7 Sep-17 17.6 0.05 Dec-11 70.1 63 Sep-17 0.105 0.11
BOLD = Applicable Guideline Criteria BOLD = Parameter Exceeds Recommended Guideline Criteria *Alberta Tier 2 Soil and Groundwater Remediation Guidelines (Table 2). February 2016. (All concentrations in mg/L = ppm, unless noted)
- -- = No value provided in guidelines
Sample ID Sample Date Total Chromium Hexavalent Chromium Alberta Tier 2 Guideline (Commerical Land Use)* M11-01 M11-02 M11-03 M11-05 M11-14 M11-22 % Reduction Hexavalent Chromium 100% 100% 100% 99.99% 99.75% 99.83%
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Results
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Results
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Results
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Conclusions
Outcome - success in plume reduction Learning – do not use galvanized CSP Learning – Explore pathway elimination Next Steps…
Confirmatory Soil and GW Sampling in 2018 Risk Management for residual plume Decommissioning
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