A combination of high vacuum extraction and in situ chemical oxidation for the recovery and destruction of chlorinated hydrocarbons

Transcription

1 A combination of high vacuum extraction and in situ chemical oxidation for the recovery and destruction of chlorinated hydrocarbons Project of the Year 500k to 2mill

2 PROJECT SETTING Figure 1: The Mersey Gateway Bridge Figure 2 (right) bridge route and location plan 600M infrastructure project between Widnes and Runcorn 2M advance works contract for the remediation of Catalyst Trade Park Contaminated with chlorinated solvents, arsenic, lead and radioactive materials Project risks due to regulatory position and maintaining Bidder and funder confidence 2

3 Site History Site formerly occupied by chemical works from the 1800 s until the 1990 s Known to have a history of chlorinated solvent use and extensive contamination of ground and groundwater Also associated with production of uranium during the Second World War Rumoured to have been involved with mustard gas trials Need for remediation works identified at a very early stage Despite this, the economic and traffic flow benefits of maintaining this route option outweighed the contamination risks

4 RECENT SITE HISTORY Later uses included experimental/trial chemical processes using a range of chlorinated solvents 4

5 Ground Conditions Approximate boundary of alluvial channel

6 Cone Penetration Testing Works CPT Rig mounted Membrane Interface Probe (MIP) Real time measurement of chlorinated solvent concentrations at 5cm depth intervals

7 CHLORINATED SOLVENTS Approximate boundary of alluvial channel Identified in the made ground, alluvium and glacial sand deposits Highest concentrations observed in the alluvium

8 Figure 8: Aerial Photo of the Site and Treatment Areas Project of the Year Award 500k to 2mill Site Setting 8 REMEDIATION AREAS A wide range of chlorinated solvents, inclu trichlorethanes (TCA), tetrachlorethanes PC trichloroethene (TCE), chlorofororm, carbo tetrachloride and tetrachlorethene (PCE) Contamination DNAPL considered likely to be present whe sum of the chlorinated solvent concentratio >10% of their solubility this defined 5 remediation areas

9 Remediation Objectives and Strategy Figure 8: Aerial Photo of the Site and Treatment Areas Site Setting Project of the Year Award 500k to 2mill Objectives: Betterment through recovery of chlorinated solvents from the made ground and granular alluvium deposits beneath the site using Best Practicable Techniques Strategy: Phase 1 Pilot Trials of Selected Remedial Techniques Phase 2 Active Remediation Stage 1 Multiphase Extraction (MPE) to recover mobile hydrocarbon mass Stage 2 In Situ Chemical Oxidation (ISCO) to target residual hydrocarbon mass

10 PHASE 1 FIELD TRIAL Field Trials to demonstrate the selected remedial techniques are the best practicable techniques. Remedial Options Appraisal identified a combination of Multi Phase Extraction (MPE) and In Situ Chemical Oxidation (ISCO) as the most best practicable techniques. Stage 1 Multiphase Extraction (MPE) to recover mobile hydrocarbon mass Stage 2 In Situ Chemical Oxidation (ISCO) to target residual hydrocarbon mass 10

11 PHASE 1 FIELD TRIAL OBJECTIVES Zone of influence to confirm borehole spacing is adequate Vacuum Influence Vapour Abstraction Rate (Pore Volume Exchange Time) Groundwater Draw Down Hydrocarbon mass recovery rate through monitoring of: Vapour Concentration Vapour Composition Vapour Abstraction Rate Groundwater abstraction Dissolved phase composition DNAPL Characterisation MPE Field Trials Objectives 11

12 Treated Water Storage Tank Granular Activated Carbon Vessel Oil Water Separator HVE System Chemical Mixing Tank

13 PHASE 1 PILOT TRIAL RESULTS Vacuum Influence Vacuum Influence (mbar) Baseline 30 minutes 2 hours 8 hours 13

14 No change in GW Level in Made Ground Layer Groundwater Level 4 m Change in GW Level at BH184 > CBHA6 1 and CBHA6 14

15 Vapour Concentration Multiple Test Wells 1,500 2,500 ppm (1,767 ppm) Single Test Well 105 4,340 ppm (724 ppm) Chlorinated Hydrocarbons = 96.5 % 97.5%

16 PHASE 1 PILOT TRIAL RESULTS Vapour Pore Volume Exchange Rate Single & Multiple Test Wells Vapour abstraction rate between 81 m 3 /hr to 191 m 3 /hr 17 to 22 times pore volume exchanged per day Hydrocarbon Vapour Mass Recovery Rate Single Test Well 0.22 kg/hr to 0.41 kg/hr Multiple Test Wells 0.65 kg/hr Extrapolated Mass Recovery Rate = 8.6 kg/hr or kg/day 16

17 ELUSIVE DNAPL

18 PHASE 1 PILOT TRIAL RESULTS DNAPL Characterisation First positive identification of DNAPL in ground 81.2% Chlorinated Hydrocarbons BTEX, Methyl Benzenes 18

19 PHASE 1 FIELD TRIAL OBJECTIVES ISCO Field Trials Objectives Zone of influence to confirm borehole spacing is adequate Redox Potential in Groundwater Change in dissolved phase concentration Dissolved Oxygen Temperature ph Effectiveness of ISCO in field conditions 19

20 PHASE 1 FIELD TRIAL OBJECTIVES ISCO Injection Method Original Injection Method Revised Injection Method 20

21 Zone of Influence Redox Baseline 1.5 Hours Injection Redox Potential (mv) 3 Hours Injection 18 Hours Post Injection 5 days Post Injection 8 days Post Injection

22 Dissolved Phase Concentration TCE Concentration (µg/l) Baseline 1 Day Post Injection 5 Days Post Injection 8 Days Post Injection 55% 95% Reduction in Concentration

23 FULL SCALE REMEDIATION WORKS 121 MPE treatment wells across eight remediation zones 4 Extraction Systems 2 Injection Systems

24 Multi Phase Extraction Installation of four MPE systems to recover volatiles organic compounds from alluvium and made ground. Contaminant mass recovered as i) vapour phase, ii) dissolved phase in groundwater and iii) as DNAPL. Process is highly measureable using in line flow and concentration measurement. Regular system optimisation to focus treatment on most productive areas.

25 SITE SETTING Multi Phase Extraction (MPE) System Design Dewatering Unit (MPE) System High Vacuum Extraction Unit Oil Water Separator Water Treatment System Air Stripper Granular Activated Carbon Vapour Treatment Granular Activated Carbon 25

26 Project of the Year Award 500k to 2mill Treatment System KPIs: System Performance Hydrocarbon Mass Recovered 100% reuse of abstracted groundwater Health, safety and environmental incidents Programme Daily monitoring and maintenance Daily to weekly optimisation Full time site team Real time monitoring of system key performance indicators 24/7 operation >90% operational time throughout the remedial programme

27 Contaminant Mass Recovery Monitoring Individual Well Hydrocarbon Vapour Mass Recovery Rate (kg/hr)

28 Contaminant Mass Recovery Monitoring

29 Daily Hydrocarbon Mass Recovery Rate

30 Multi phase extraction the three phases. Results Over 5.4 million m 3 of vapour and nearly 7.5 tonnes of total vapour mass recovered Over 46 million litres of water treated Almost 7 tonnes of dissolved phase hydrocarbon recovered Abstracted groundwater treated and re injected to eliminate discharges to foul sewer and aid treatment process System design enhanced neat solvent recovery from wells Systems modified to aggressively recover this free phase product Total free phase hydrocarbon mass recovery of 2.7 tonnes

31 Carbon Dioxide Supersaturated Water Injection First UK field pilot trial of carbon dioxide supersaturated water injection to enhance solvent recovery. Enhanced volatilisation of volatile hydrocarbons and mobile trapped solvent in the soil matrix. CO 2 SWI Pilot Scale Plant Schematic Diagram of CO 2 Injection in Subsurface

32 Innovation Project of the Year Award 500k to 2mill Recovered Hydrocarbon Vapour Concentration Carbon Dioxide Supersaturated Water Injection Mass recovery rate increased by up to 394%. Figure 16: (above) CO 2 SWI Pilot Scale Plant Figure 17: (right) Schematic Diagram of CO 2 Injection in Subsurface

33 In Situ Chemical Oxidation (ISCO) Destructive technology used to treat remaining chlorinated hydrocarbon mass Continuous monitoring of groundwater to demonstrate the oxidant had been successfully delivered. Monitoring and modeling to map treatment effects on contaminant concentrations. (above) Chemox injection manifolds and flow meters (right) details surfer plots of injection monitoring results

34 SITE In Situ SETTINGChemical Oxidation (ISCO) and Multi Phase Extraction (MPE) System Design ISCO Injection System MPE System Dewatering High Vacuum Unit Extraction Unit Oil Water Separator Water Treatment System Air Stripper Granular Activated Carbon Vapour Treatment Granular Activated Carbon 34

35 Remedial Techniques ISCO Volume Distribution of Hydrogen Peroxide and Ferrous Sulphate Injected Almost 600,000 litres of oxidant injected Injected Volume (m 3 ) - Injection Borehole - Monitoring Borehole

36 Remedial Techniques ISCO

37 Dissolved Phase Chlorinated Hydrocarbons Effective Solubility (Baseline) (4 days post injection) Legend Monitoring Borehole Chemical Oxidant Injection Borehole Effective Solubility (Fraction) (15 days post injection) 98% reduction in chlorinated hydrocarbon concentrations A2-3 A2-5 A2-2 A2-8 A2-1 A2-4 BH187 A2-7 A2-10 A2-13 WS30 A2-9 A2-6 A2-12 A2-11

38 Verification Monitoring Borehole Monitoring Data Over Time

39 DISSOLVED PHASE TRICHLOROETHENE (TCE) CONCENTRATION OVER TIME 39

40 PROJECT OUTCOMES Remediation works delivered on time to strict timescale and on budget Collaborative, cooperative and transparent working, in the spirit of NEC3 Contract Proactive engagement and consultation lead to rapid regulatory approval No lost time incidents demonstrating that an efficient and sustainable remedial solution could be achieved without compromising health and safety. Performance beyond compliance certification achieved Considerate constructors scheme. Sign off by regulators within 1 week and successful achievement of Betterment target. 17 tonnes of contaminant mass recovered. 40

41 ACKNOWLEDGEMENTS Environment Agency: Janice Holland, Jeni Templeman HBC EHO: Will Watson, Chris Culley Halton Borough Council: Steve Nicolson, Jeff Hayes Ramboll: Phil Studds, Peter Fitch, Nigel Cossons Celtic Technologies: Trevor Bamber, Chris Hughes, Chris Wood, Paul Lambe, John Lambe, Sean Filkins, Dewi Atkins, David Duncan 41

42 Thank You Chris Taylor King Celtic and Biogenie