Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash Paper 7191 Presented at: Waste Management 07’ Symposium Tuesday, February 25 - March 1, 2007 Session 29: Performance Assessment of Geological Disposal Systems Tuesday, February 27, 2007: 8:30 AM Tucson Convention Center Room: Coconino By: Arturo Woocay and John C. Walton Environmental Science and Engineering The University of Texas at El Paso

Acknowledgement This work was funded by the Nye County, Nevada, Nuclear Waste Repository Project Office through cooperative research grant DE-FC28-02RW12163 from the U.S. Department of Energy, Office of Civilian Radioactive Waste Management

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash3 Overview Introduction Yucca Mountain Region Amargosa Desert Region Water Levels Geochemical Data from the Region Previous Work Introduction to Multivariate Statistical Methods (MSM) Correspondence analysis (CA) k-means Cluster Analysis (KMCA)

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash4 Overview (Cont’d) MSM Results Nine separate hydrochemical facies At least two potential flowpaths Very distinct flowpath under Fortymile Wash Corroborating Isotopic Data Oxygen-18 Hydrogen-2 Hydrogen-2 vs Oxygen-18 compared to GMWL Conclusions

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash5 Amargosa Desert Yucca Mountain Fortymile Wash

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash6 Amargosa Desert Region Water Levels

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash7 Major Ion Chemistry from the Amargosa Desert Region Major Ions pH Ca 2+ (mg/L) Mg 2+ (mg/L) Na + (mg/L) K + (mg/L) Cl - (mg/L) SO 4 2- (mg/L) Total Alkalinity (CaCO3 mg/L) 211 wells/springs Use MSM: CA & KMCA

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash8 Major Ion Chemistry Piper (Trilinear) Diagrams

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash9 Introduction to MSM MSM are powerful tools for : Investigating large complex data sets Identifying parameters that describe a system and its behavior Discovering patterns and relationships

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash10 Introduction to MSM (Cont’d) Some types of MSM: Principal Component Analysis Canonical Correlation Analysis Factor Analysis Correspondence Analysis (CA) Cluster Analysis k-means Cluster Analysis (KMCA)

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash11 Correspondence Analysis A weighted Principal Component Analysis (PCA) of a contingency table Transforms correlated data into mutually orthogonal dimensions Each successive dimension includes decreasing amounts of variation Better that PCA for finding and interpreting nonlinearity in the system Reduce number of dimensions of the system

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash12 k-means Cluster Analysis Nonhierarchical supervised partitioning cluster analysis Minimize variability within each cluster and maximize it between clusters Uses Euclidean distances and centroids One initial “seed” per k-cluster then centroids are recalculated after each observation is clustered The number of desired groups must be predetermined

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash13 MSM Results Using Major Ion data from 211 wells/springs in the Amargosa Desert Region CA conducted in Statistica 7 Reduce the number of variables Detect relationships between variables k-means Cluster Analysis (CA) Nonhierarchical supervised partitioning CA Empirically determined 9 groups Analyze the first 3 CA dimensions

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash14 Interpretation of CA Dimensions Dimensions Coordinates for Major Ion Data Dim 1Dim 2Dim 3 pH Ca Mg Na K+K Cl SO Alkalinity Explained Variation % Dimension 1: Separation of pH, Alkalinity & Na+ from Ca 2+ & Mg 2+ and Cl- & SO 4 2- Dimension 2: Separation of Ca 2+ & Mg 2+ from Cl -, Na + & SO 4 2- Dimension 3: Explains less than 10% of variation

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash15 k-means CA Interpretation

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash16 Biplot of Dimension 1 - Dimension 2 Can Identify 9 Separate Groups with Cluster Analysis

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash17 Summary of Major Ions by Group Group NamepH Ca 2+ (mg/L) Mg 2+ (mg/L) Na + (mg/L) K + (mg/L) Cl - (mg/L) SO 4 2- (mg/L) Alkalinity as CaCO 3 (mg/L) TDS (mg/L) Yucca Mountain West Face Yucca Mountain East Face Mid Fortymile Wash Oasis Valley Amargosa Desert SW High Alkalinity East of Fortymile Wash Amargosa Desert East High Ca & Mg

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash18 Hydrochemical Facies and Processes

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash19 Dimension 1

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash20 Dimension 2

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash21 MSM Conclusions GW chemistry reflects prominent surface features more that contemporary water levels GW chemistry below Oasis Valley and following the Amargosa River GW below Yucca Mountain different from Fortymile Wash Some connection between Amargosa Valley and Death Valley Possible upwelling from carbonate aquifer Very distinct signature around Fortymile Wash

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash22 Corroborating Isotopic Data Oxygen-18 Hydrogen-2 Hydrogen-2 vs Oxygen-18 compared to GMWL

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash23 δ 18 O

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash24 δ2Hδ2H

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash25 Deviation form the GMWL

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash26 δ 2 H vs. δ 18 O Cold (7 o C) S = 6.1 More humid and colder climate than contemporary (Clark and Fritz 1997, p. 49 after Gat, 1980) Craig , Int At Engy Agy (IAEA) global network IAEA World Met Org (WMO) true

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash27 δ 2 H vs. δ 18 O Down Fortymile Wash Following the Amargosa River Mixing with Amargosa River

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash28 Conclusions Distinct signature along Fortymile Wash Closely follows topography Lower TDS than adjacent water Younger than adjacent groundwater Implying: focused infiltration in the past of colder surface water in the wash that decreased as runoff events diminished Runoff events diminished as climate became warmer and dryer Contemporary groundwater flow may be slower than currently predicted

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash29 Questions?

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash30 Predicted Saturated Zone Particle Trajectories from Yucca Mountain From: Technical Basis Document No 11: Saturated Zone Flow and Transport Revision 2

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash31 ISIP Background The Nuclear Waste Policy Act (NWPA) in 1983 directed DOE to develop a geologic repository to dispose of the nation’s spent nuclear fuel and high-level waste. In 1987, Congress amended the NWPA and designated Yucca Mountain as the only site to be considered. The NWPA authorizes Nye County as the "site" jurisdiction and host county, to conduct on-site representation at Yucca Mountain. In 1987 Nye County Board of Commissioners creates the Nye County Nuclear Waste Repository Project Office (NWRPO) to monitor and assess the federal effort to find a repository site. In 1993, the County hired a full-time on-site representative and the Independent Scientific Investigations Program (ISIP) is established. Though ISIP the County gathers data for independent analysis of geologic and hydrologic conditions and monitors and reviews DOE's scientific characterization of Yucca Mountain ISIP activities involve drilling and instrumenting boreholes, analyzing the geology and geochemistry of drill cuttings, instrumenting tunnels and drifts, monitoring, data analysis, and numerical modeling activities to address the concerns of Nye County.

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash32 ISIP Background The Nuclear Waste Policy Act (NWPA) in 1983 directed DOE to develop a geologic repository to dispose of the nation’s spent nuclear fuel and high-level waste. In 1987, Congress amended the NWPA and designated Yucca Mountain as the only site to be considered. The NWPA authorizes Nye County as the "site" jurisdiction and host county, to conduct on-site representation at Yucca Mountain. In 1987 Nye County Board of Commissioners creates the Nye County Nuclear Waste Repository Project Office (NWRPO) to monitor and assess the federal effort to find a repository site. In 1993, the County hired a full-time on-site representative and the Independent Scientific Investigations Program (ISIP) is established. Though ISIP the County gathers data for independent analysis of geologic and hydrologic conditions and monitors and reviews DOE's scientific characterization of Yucca Mountain ISIP activities involve drilling and instrumenting boreholes, analyzing the geology and geochemistry of drill cuttings, instrumenting tunnels and drifts, monitoring, data analysis, and numerical modeling activities to address the concerns of Nye County.

February 27, 2007Woocay-Walton: Multivariate Statistical Analyses of Groundwater Surrounding Fortymile Wash33 Nye County, Nevada Located in the south-central portion of Nevada Third largest county in US (11,560,960 acres) About 22 % designated for federal restricted access or for U.S. government classified activities. Includes: Nevada Test Site Nelis Air Force Range Tonopah Test Range Yucca Mountain Project