Impacts of DNAPL Contamination in Fractured Rock Aquifers Used for Municipal Water Supply

Size: px

Start display at page:

Download "Impacts of DNAPL Contamination in Fractured Rock Aquifers Used for Municipal Water Supply"

Douglas Moore
5 years ago
Views:

1 Impacts of DNAPL Contamination in Fractured Rock Aquifers Used for Municipal Water Supply Beth Parker Professor & NSERC Chair University of Guelph, Ontario, Canada Round Table 2 September 16, 2009

2 Fractured Rocks Sedimentary Rock Granite Karst

3 DNAPLs Commonly Pass Through Overburden Into Bedrock DNAPL source zone initial condition PCE Mackay and Cherry, 1989

4 Silurian Dolostone Belt (shown in blue) Lake Huron Guelph and damabel Formations at site Guelph Cambridge Aquifer supplies Lake Ontario ~ 1 million people Buffalo Lake Erie Satellite Image from NASA (

5 Communities in Grand River Basin using Groundwater nearly 1 million people drinking groundwater

6 Sources of industrial contaminants exist throughout cities

7 Pesticide Plume in Dolostone Aquifer Plume within Municipal Well Field Discovered in 1992 G5 TCE P15 P9 UW16B UW13 Metolachlor G6 Syngenta Field Site P10 P11 P m G17 G18

8 DNAPL Origin for Deep Herbicide and TCE Contamination in a Dolostone Aquifer CONCEPTUAL MODEL FOR INTERMINGLED PLUMES TCE Metolachlor overburden dolostone aquifer Initial DNAPL zones Intermingled

9 Nature of Contamination in Fractured Sedimentary Rock vadose zone SOURCE ZONE PLUME ZONE groundwater zone PLUME FRONT

10 Small Fracture Porosity and Large Matrix Porosity 0.1 to 0.001% 001% 2 to 25% DETAIL A mineral particle A Microscopic view of rock matrix

11 How fast do plumes travel in fractured rock aquifers?

12 AVERAGE LINEAR GROUNDWATER VELOCITY v v K b [ Δh / ΔL] = where φ f = bulk fracture porosity φf K b = bulk hydraulic conductivity

13 Commercially Available DFN Models HydroGeoSpher e

14 Key Issues: How many active fractures? What is their Interconnectivity? Dense Network Sparse p Network

15 Contaminant Plume: Constant Source Well-Connected Fracture Network Simulated 50 years C/C o vert8t.pre v Kb i = ~ 1200 m year Groundwater Travel φ Distance ~ 60 km f / f v f D gw R a = = v D s s ~ 100 Plume front migration much slower than groundwater flow in fractures Strong Plume Front Retardation

16 Contaminant Plume: Constant Source Sparse Network with Major Fractures Simulated 50 years C/C o ver11f.pre v Kb i = ~ 2900 m year Groundwater Travel φ f / f Distance ~ 145 km

17 Key Points Two systems with similar K bulk Much more rapid plume transport in case with fewer, well-connected, larger fractures

18 Cross - Section Showing Plume Extent NW SE?

19 Metolachlor Arrived at Well G6 in 2001 after 20 years of Migration G5 TCE P15 P9 P10 P11 P17 UW16B UW13 Syngenta Field Site Metolachlor G6 Arrival m G17 G18

20 Metolachlor Concentration Arrival in G6 Pumping Well Drinking Water Limit is 25 μg/l Metolac hlor (ug/l) MDL = 0.5 ug/l 0.0 Oct-00 Apr-01 Oct-01 Apr-02 Oct-02 Apr-03 Oct-03 Apr-04 Oct-04 Date

21 Transect to Investigate Plume ( ) OW19 Syngenta Property OW2 UW2 COM DEV Property UW1 UW16B OW16 Transect OW13 UW m Approximate Groundwater Flow Direction OW24 Parking Lot OW42 UW5 UW4 Municipal Supply Well G6 ~620 m southeast UW13 UW6 Conventional Wells Previous UW Coreholes Recent UW Coreholes Meters N

22 Aqueous Metolachlor along the plume longitudinal section 1000 Metolachlor (ug g/l) OW OW Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Date ) Metolachlor (ug/l) OW OW Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Date Metolachlor (ug/l) MDL = 0.5 ug/l Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Date G6

23 Metolachlor Concentrations Based on Multilevel Results on Transect 300 W (October 2005) E UW5 280 UW4 UW13 UW6 UW3 Northing (m) * Metola achlor (u ug/l 180 MDL = 0.5 ug/l 160 Kriging, Anisotropy Ratio: 8: Easting (m)

24 Key Points Plume at quasi-steady state in fracture network Nearly all contaminant mass is in low permeability rock matrix Plume maintained by back-diffusion

25 Conclusion: Pesticide id Plume Although h this industrial i site has a major long-lasting plume, it has not been necessary to remediate because detailed studies show that the plume is not doing harm within the domain of this municipal well field. High resolution data sets prevented expensive and ineffective remediation

26 Field Validation of Fracture Network Characteristics: PCE Contaminated Shale Watervliet Arsenal Building 40 Area Hudson River

27 Bedrock Geology Watervliet Site Ordovician Shale (Snake Hill Formation) Black, slightly metamorphosed, laminated shale Matrix porosity 2-5% Sub-horizontal to steeply dipping fractures and bedding plane separations Calcite / pyrite py accumulation on many fractures

28 Initial Fracture Network Conceptual Model: Based on Borehole Flow Tests Results from USGS Study Published in Journal of Hydrology 2002 Tests in open boreholes

29 One Major Transmissive Zone Identified from BH Flow Logging, 2001 USGS,

30 Flowmeter and ATV Logs Two or Three Flow Zones per Hole Williams and Paillet, 2002

31 Initial Conceptual Model: Few, Large, Continuous Fractures Dominate Flow Williams and Paillet, 2002

32 Standard Practice

33 New Lines of Evidence for Fracture Network Characteristics 1. Rock core VOC profiles 2. FLUTe TM Hydraulic Conductivity Profiles 3. VOC packer sampling during drilling 4. Multi-levels levels for hydraulic head and groundwater sampling 5. Pilot and full-scale MnO 4 injections with multi-level level monitoring High Resolution Data

34 Core Sampling for Migration Pathway Identification cored hole rock core TCE mg/l fractures core samples analyzed non-detect Fractures with TCE migration B.L. Parker, 2000

35 Rock Core VOC Profiles show Transport in Many Fractures VOC Pathways VOC Pathways Overburden Flow zones identified by borehole flow testing

36 Resulting Velocity Profile from FLUTe TM Liner Installation

37 Watervliet FLUTe Transmissivity & Geophysical Profiles at IW-1 ft bgs) Depth (f flow zones identified by BH flow testing

38 DNAPL Serves as a Tracer for Many Hydraulically Active Fractures

39 Alternative Conceptual Model: Lots of Interconnected Fractures FRACTRAN Example: Well-Interconnected t Fracture Network

40 Depth Discrete Multilevel Systems Solinst FLUTe Westbay

41 FLUTe Multilevel System (Temporary Monitoring during Initial Injections) Installation & K-Profiling N 2 tank 5 holes, 150-ft deep IW-1 toiw-4 IW-4, MW-79 9 ports each Sampling manifold

42 Full-Scale NaMnO 4 Injections Carus Chemical Co. NaMnO 4 (40wt%) 500 gal Mixing / Injection Tank Double diaphragm Pump Gravity and low pressure (10-15psi) injection Injection Summary Well-head Seal / Vent

43 MW-79 Inj#3a Depth (ft bgs) 0 MW-79 IW-1 to IW-4 20 port packer ft 85 ft 120 ft 80 ft 160

44 MnO 4 Distribution in FLUTe Multilevels May 2005: End of MW-79 Inj#3a Distance from MW-79 (ft) MW-79 packer

45 Comparison: Extent of MnO 4 versus Elevated Sulfate SO 4 SO 4 SO 4 SO 4 Elevated sulfate more widespread; MnO 4 consumed before reaching ports Well interconnected fracture network

46 Key Point: Numerous Interconnected Fractured Evident at this Site Dense Network Sparse p Network

47 Key Point Permanganate was delivered throughout the contaminated zone because of numerous, interconnected active fractures

48 Implications for Well-Interconnected Fracture Network vs. Super Highway Influences: ~ Where and how best to Monitor ~ Predictions of contaminant transport and fate ~ Adequacy of Insitu remediation system designs ~ Accuracy of system performance assessments Note: mass persists in lower permeability zones

49 Conclusions Plumes in fractured sedimentary rock are strongly retarded d and attenuated t due to dispersion, diffusion and sorption St t d ti i Strong retardation requires numerous, interconnected fractures that are evident using new DFN investigation methods

50 Acknowledgements Canadian NSERC Industrial Research Chair: Groundwater Contamination in Fractured Media 14 Corporate sponsors: Site Owners, Municipalities, Technology Companies UoG Research Team: John Cherry, Steve Chapman, Jessi Meyer, Pete Pehme, Amanda Pierce, Paulo Lima, Glaucia Lima, Jonathan Kennel and Ryan Kroeker, Maria Gorecka, Rashmi Jaheda Academic Collaborators: Aravena, Al, Balcom, Molson, Gorecki, Borchardt, Mayer, Hatfield 18 graduate students ( present)

51 Appreciation Muito obrigada à comissão organizadora do evento pelo convite feito a mim para essa apresentação e a todos da audiência pela atenção. Sendo minha primeira visita ao Brasil, sinto-me honrada em poder falar com vocês hoje. Perguntas? Thank you very much to the event s organizing committee for the invitation to give this talk and to the audience for your attention. Being my first visit to Brazil, I am honoured in talking to you today. Questions?

52 The End

55 Approach: Combination of Old and New Methods Standard d (open borehole): Borehole geophysics Straddle packer testing Flow metering New (lined borehole): FLUTe K profiling / hole sealing Temperature profiling in lined hole High resolution multilevel systems focused on aquifer-aquitard aquitard issues

56 Summary Groundwater velocities in fractured rock are very fast Some contaminants can be strongly retarded and attenuated, but depends on rock and contaminant properties Bedrock aquifers and aquitards require high-resolution characterization for improved prediction and decisionmaking DFN Field Approach

57 Nature of Contamination in Fractured Sedimentary Rock Requires a Different Approach vadose zone SOURCE ZONE PLUME ZONE groundwater zone PLUME FRONT

58 Studies of Contaminants in Sedimentary Rocks Offer the Advantage of Diffusion Halos Sedimentary Rock Granite

59 Contamination in Fractured Non-Porous Media (FNPM)

60 Contamination in Fractured Porous Media (FPM)

61 Contamination in Granular Porous Media (GPM)

62 Terminology ogy GPM Granular Porous Media FNPM Fractured Non-Porous Media FPM Fractured Porous Media DFN Approach is Crucial for Time of Travel

63 DNAPL Phase Initially Resides within Fractures Fracture Aperture 2b φ f H 2 O φ m DNAPL φ m Matrix porosity is 1000 times greater than fracture porosity Fracture Spacing

64 DNAPL Disappearance from Fractures by Diffusion Parker et al., Ground Water (1994) Fracture Aperture 2b φ f φ m 2 φ f φ φ f m H O DNAPL φ m Dissolved Fracture Dissolved Phase Spacing Phase Early Intermediate Later Time

65 Terminology ogy GPM Granular Porous Media FNPM Fractured Non-Porous Media FPM Fractured Porous Media DFN Approach is Crucial for Time of Travel

66 Diffusion Into Rock Matrix Porous Rock Matrix Fracture Diffusioni Halo

67 Fick s First Law C J = -φ D D m e x w

68 Stylistic Comparison of Contaminant Profiles C/C o core vert8t.pre C t i t 50 C t t S Contaminant 50 years: Constant Source Well-Connected Fracture Network

69 Core Hole for Rock Core Analyses in Areas of Previous DNAPL Occurrence cored hole vadose zone groundwater zone

70 Wire-line Core Barrel

71 Stylistic Similarity of Field and Model Field Profile 35B TCE (mg/l) Model at X=70m; 50 years 50 TCE (mg/l) Depth (m bgs) Z (m) Note: Assumed TCE solubility = 1400 mg/l to convert model C/Co to mg/l

72 Watervliet FLUTe Transmissivity & Geophysical Profiles at IW-1 flow zones identified by BH flow testing gs) Depth (ft bg

73 PCE and Degradation Products in Groundwater South North Discrete Interval sampling ( ) TCE PCE cis-dce TD = 160 ft bgs

74 Hydraulic Head and VOCs CMT Multilevel MW Head (m AMSL) CMT MW-75 [VOC] (μg/l) CMT MW-75 PCE TCE CMT Layout cis-dce VC 1 Depth (m bgs) /02/ /05/ /25/

75 Key Points: VOCs in Groundwater VOCs present in nearly all sample intervals Large concentrations deep (> 50m) despite upward hydraulic gradients DNAPL penetration and transport in well- interconnected fracture network

76 Any Given Borehole Gives Only a Few Large Transmissive Fractures FRACTRAN Example: dense fracture network

77 Guelph Formation Dolostone in Nearby Outcrops

78 Investigate Plume Characteristics and Behavior Using Transect G5 TCE P15 P9 P10 P11 P17 UW16B UW13 Syngenta Field Site Metolachlor G m G17 G18

79 Multilevels in UW Coreholes along West-East Cross-Section UW5 UW13 OW13 UW6 OW13-BR 330 W E 310 OW24 UW4 OW42 OW9 UW3 290 Overburden (masl) El levation TCE and Metolachlor Plume Sampling Port Dolostone Aquifer Shale Pressure Transducer & Sampling Port Distance (m) 320

80 Fractured Porous Rocks Bedding planes and joints in dolostone Sandstone with shale interbeds Interbedded sandstone and shale

81 Hydrogeology ogy Terminology ogy GPM Granular Porous Medium sands & gravels Karst Conduit some limestones & dolostones FNPM Fractured Non-Porous Medium granites FPM Fractured Porous Medium sandstone shale mudstones clays,silts

82 Distribution of Sedimentary Rocks in North America Sedimentary bedrock Igneous, volcanic, and metamorphic bedrock Source: Heath, 1988

83 Nearly all people and industry reside in areas overlying sedimentary bedrock Igneous, volcanic, and metamorphic bedrock Sedimentary bedrock with most of population Population year 2000

84 What do we know about fracture networks? Photos (outcrop, borehole image, core logs)

85 Orthogonal Fracture Sets in Sandstone California i Site

86 FLUTe liner pressed tightly against borehole wall to seal without liner with liner

88 MW-25 between 9 and 12 mbgs d Doloston e Guelph Formation Mti Matrix Porosity (1-20%) MW-25 between 73 and 76 mbgs Amabel Formation

A High Resolution Vertical Gradient Approach for Delineation of Hydrogeologic Units at a Contaminated Sedimentary Rock Field Site

A High Resolution Vertical Gradient Approach for Delineation of Hydrogeologic Units at a Contaminated Sedimentary Rock Field Site Jessica Meyer 2013 - Solinst Symposium High Resolution, Depth-Discrete