In-Situ Chemical Oxidation from Pilot Study to Full-Scale Implementation

Transcription

1 21 st International Petroleum Environmental Conference In-Situ Chemical Oxidation from Pilot Study to Full-Scale Implementation October 15, 2014 Joann Lin, E.I.T.

2 Co-authors: Jim Leu, Ph.D., P.E. Michelle Morales, E.I.T Susan Ferris, P.G. Authors Parsons Presenter: Joann Lin, E.I.T. 2

3 Presentation Overview Site Background Review of Pilot Study Full-Scale Ozone/Oxygen Sparging Respiration Test Contingency Planning SVE GW Parameters and Analytical Results Conclusions Lessons Learned 3

4 Off-Site versus On-Site Treatment 4

5 Chronology of Key Site Events 1999 Vapor Intrusion Study 2005 ORC Injection Study 2009 ISCO Bench Test 2012 ISCO Bench Test Groundwater Extraction Soil Vapor Extraction/Air Sparging Remediation 2007 Remedial Process Optimization 2010 ISCO Pilot Test Full Scale ISCO Implementation

6 Site Background Nature and Extent of Impacts Chemicals of Concern identified in saturated zone: Gasoline Range Organics (GRO) Diesel Range Organics (DRO) Motor Oil Range Organics (ORO) Matrix GRO DRO ORO Groundwater (µg/l) 3,500 5, Clean-up Levels (µg/l)

7 ISCO Ozone Pilot Test Site Layout AS-1 7

8 ISCO Pilot Test Pilot Test Injection Specifications Injection pressure: 5.5 to 6.0 psi Sparge flow rate: 3.5 cfm per well Equivalent to ~ 4 lb O 3 /day (2 lb O 3 /day/well) ROI ~20 ft Alternating pulse period 60 minutes 8

9 Pilot Test Results - DRO Concentration Injection Start Injection End 9

10 Ozone Injection Pilot Test Results ISCO using ozone successfully destroyed COCs in saturated zone Byproducts (hexavalent chromium and bromate) were detected in only NMP-1 Hexavalent Chromium (max 44 µg/l) decreased to baseline levels in three months Bromate (max 110 µg/l) decreased to near baseline levels in one month Ozone/VOCs did not impact offsite residence and can be contained within treatment zone 10

11 Full-Scale Ozone Injection Implementation Injection Wells = 6 Treatment Monitoring Wells = 8 Transition and Compliance Wells = 10 Injection pressure: 12 to 25 psi Sparge flow rate: 6.8 cfm per well Ozone Capacity: 27 ppd ROI: 20 ft based on DO and ORP measurements 11

12 Actual Oxygen/Ozone Sparging Layout 12

13 Pre-Field Activities 13

14 Ozone System Layout 14

15 Operation Optimization Standard Injection Interval per well: 60 minutes After four months of operation, focused ozone operation at hot spots Injection intervals were also adjusted based on concentrations and VOC off-gassing Increased from 60 to 90 minutes in AS-2 and OS-3 Decreased from 60 to 30 minutes in AS-1 and AS-3 15

16 Soil Vapor and Groundwater Monitoring Wells 16

17 Soil Vapor Extraction Ozone offgassing was not detected in the ozone treatment wells Due to elevated PID concentration in the wellhead of MW-10 one month after operation, SVE was conducted at MW-10 for three weeks Dual phase extraction was conducted at TW-2, which had elevated PID readings Initial PID were approximately 900 ppmv and decreased to 20 ppmv after 6 months of operation 17

18 Pump Test at TW-2 Placed pressure transducers within TW-2 and two downgradient wells (MW-8 and MW-2) Tested three cases over 33 hours No remediation system (Control) GWE only GWE and SVE In all cases, GW elevation decreased with GWE and SVE operation 18

19 Pump Test at TW ft 2.62 ft 2.52 ft 19

20 Pump Test at MW-8 (35 Foot From TW-2) 5 GWETS On SVE On ft 2.78 ft 2.45 ft GW Level (ft) Time (hours) MW-8 GW Level TW-2 GW Extraction Status TW-2 SVE Status 20

21 Pump Test at MW-2 (40 Foot From TW-2) 5 GWETS On SVE On GW Level (ft) ft ft 0.81 ft Time (hours) MW-2 GW Level TW-2 GW Extraction Status TW-2 SVE Status 21

22 Ozone Treatment Wells - ph ph EW Jul-13 Aug-13 Sep-13 Oct-13 Dec-13 Jan-14 Feb-14 Mar-14 Apr-14 May-14 Jun-14 Jul-14 Aug-14 Sep-14 Sample Date MW-2 MW-3 MW-5 EW-1 EW-2 EW-6 V-11 V-13 TW-2 TW-3 22

23 Ozone Treatment Wells - Conductivity 16,000 14,000 12,000 Conductivity (um mhos/cm) 10,000 8,000 6,000 4,000 2,000 TW-3 TW-2 EW-1 EW-2 0 Jul-13 Aug-13 Sep-13 Oct-13 Dec-13 Jan-14 Feb-14 Mar-14 Apr-14 May-14 Jun-14 Jul-14 Aug-14 Sep-14 Sample Date MW-2 MW-3 MW-5 EW-1 EW-2 EW-6 V-11 V-13 TW-2 TW-3 23

24 Ozone Treatment Wells - ORP EW ORP (m mv) Jul-13 Aug-13 Sep-13 Oct-13 Dec-13 Jan-14 Feb-14 Mar-14 Apr-14 May-14 Jun-14 Jul-14 Aug-14 Sep-14 Sample Date MW-2 MW-3 MW-5 EW-1 EW-2 EW-6 V-11 V-13 TW-2 TW-3 24

25 GRO Concentration Trends 25

26 GRO Contour Prior to Remediation Persulfate and Ozone N 1, Oxygen 26

27 GRO Contour After One Year of Remediation Persulfate and Ozone Oxygen 27

28 DRO Concentration Trends 28

29 DRO Contour Prior to Remediation Persulfate and Ozone 1, ND 100 1,000 Oxygen 29

30 DRO Contour After One Year of Remediation Persulfate and Ozone Oxygen 30

31 Oxygen Respiration Test Conducted oxygen respiration at AS-2 and AS-3 Sparged for 24 hours Monitored DO at V-11 and MW-5 0, 2, 4, 6, 24 hours Determined dissolved oxygen utilization rate (DOUR) by measuring DO decrease over time Oxygen Sparging DOUR = 12 mg DO/L/day Air Sparging DOUR = 15 mg DO/L/day 31

32 Oxygen Sparging Respiration Test Results 12 Dissolved Oxygen (mg/l) y = -0.4x R² = y = x R² = Time (hours) V-11 MW-5 Linear (MW-5) Linear (V-11) 32

33 Air Sparging Respiration Test Results Dissolved Oxygen (mg/l) y = x R² = y = x R² = Time (hours) MW-8 MW-9 Linear (MW-8) Linear (MW-9) 33

34 Full-Scale Design Based on Pilot Study Test Parameter Pilot Study Full-Scale (Design) Full-Scale (Actual) Number of Injection Wells Flow Rate per Well Radius of Influence 2 ozone wells 6 ozone wells 4 ozone wells; 2 oxygen wells 3.5 cfm 6.8 cfm 6.8 cfm 20 feet 20 feet 20 feet Injection Capacity 4 ppd 10 ppd 27 ppd Injection Pressure psi 15 psi psi Injection Interval per Well 60 minutes 60 minutes 60 minutes 34

35 Conclusions GRO and DRO were reduced significantly at ozone treatment wells No byproducts (bromate or hexavalent chromium) were detected in transition and compliance wells SVE was utilized for VOC offgassing at MW-10 Dual phase extraction at TW-2 was successful Interaction between persulfate and ozone along the western fence boundary may yield better results Based on the DOUR, oxygen sparging is similar to air sparging 35

36 Questions Thank You 36

37 Extra Slides 37

38 Site Background - Site Specific Information Former natural gas processing station ( s) Interbedded layers of sand and silty sand (0-30 ft bgs) Three hydrostratigraphic layers: Shallow unconfined zone (15-30 ft bgs) Confining layer (30 70 ft bgs) Deep zone (70 90 ft bgs) Shallow unconfined zone Groundwater velocity: 0.4 ft/day Flow direction: southeast and northeast 38

39 ISCO Ozone Pilot Test Site Layout 39