Published on February 22, 2014
UNIVERSITY OF WYOJ1ING Department of Civil and Architectural Engineering Dept. 3295 • 1000 E. University Ave. Engineering Building, Room 307 4 Laramie, WY 82071-2000 (307) 766-5255 • fax: (307) 766-2221 • www.uwyo.edu Letter of Satisfactory Project Completion Lisa Denke, 2013 Wyoming EPSCoR Summer Undergraduate Fellow 21 August 2013 This letter is written to confirm that Lisa Denke has satisfactorily completed her summer research project entitled "Baseline Data : Pavillion Area Groundwater". She has conducted extensive research on historical groundwater chemistry data and has analyzed the integrity of 15 wells in the Pavillion area. The work she has completed is sufficient to be converted to a technical manuscript for publication in the Journal of Petroleum Technology or another related peer-reviewed journal. Yours sincerely, 'db:~.-:r.-s . Colberg, Ph.D. Professor firstname.lastname@example.org Tel: +1-307-766-6142 www.uwyo.edu/colberg
Baseline Data: Pavillion, WY Area Groundwater Lisa Denke Degree Program: B.S. in Mechanical Engineering Final Report for Undergraduate Summer Research Fellowship Wyoming NSF/EPSCoR Program 22 August 2013 1 | P a g e
Contents BASELINE DATA – PAVILLION, WYOMING AREA GROUNDWATER ............................................................... 3 VALUE OF PROJECT TO ME ....................................................................................................................... 3 . PROJECT DEFINITION ................................................................................................................................ 4 BASELINE DATA AVAILABILITY .................................................................................................................. 4 . DATA AVAILABILITY IN WRDS FOR THE AREA OF INTEREST (AOI) ........................................................ 6 STATISTICAL ANALYSIS OF IONIC CONSTITUENTS ................................................................................. 8 WELLBORE INTEGRITY ANALYSIS ............................................................................................................ 12 CROSS SECTION VISUALIZATION ......................................................................................................... 13 SUMMARY ............................................................................................................................................... 14 ACKNOWLEDGEMENTS ........................................................................................................................... 15 REFERENCES CITED ................................................................................................................................. 15 . 2 | P a g e
BASELINE DATA – PAVILLION, WYOMING AREA GROUNDWATER VALUE OF PROJECT TO ME This project provided an opportunity for me to transition from working in industry to working in research. While the scientific approach is the same, no matter where you work in engineering, there are some differences, mostly in “intangible” aspects of the culture. I returned to school after working for twenty years in industry: this was a huge decision. I gave up my steady job, and more importantly, the part of my identity that was attached to the job. One of the primary reasons I took this step was to improve my ability to work in different environments. Being able to adapt to different cultures will give me more flexibility and career options in the future. Having the opportunity to work in a university research setting has refined my approach to writing: it is invaluable to have Dr. Colberg’s mentoring on writing reports. Being able to make immediate use of the statistics knowledge I learned in class has solidified my skills so I am less likely to forget them. I have often grappled with big datasets in the past, but without the skill set that I gained during the course of this project. I have worked on a number of multidisciplinary projects before. This project gave me the opportunity to build on this by working on both mechanical and chemical aspects of the project. I was able to build on the knowledge I gained in groundwater contamination classes, and contemplate – not to say solve – the causes of the variation in groundwater in the study area. In this project, I had the opportunity to meet a number of people, and to try to puzzle out the Byzantine, non‐structured world of water management. There are a number of different “institutes” and academic departments, as well as government agencies, NGO’s, and corporations, who influence water research. Should I end up working in this field, it will be good background to know some of the players, and understand how the pieces do (or do not!) fit together. 3 | P a g e
PROJECT DEFINITION This project was undertaken to determine the availability of baseline groundwater data for the Pavillion, Wyoming area. The Area of Interest (AOI) for the project is defined in Figure 1. The AOI is located mainly in the Third Division of the Midvale Irrigation District. 1 The area coincides with Pavillion Gas Field. BASELINE DATA AVAILABILITY DiGiulio et al. (2011) reported on EPA’s extensive measurements of constituents in Pavillion area groundwater. EPA measured the following: 1. Inorganic ions (e.g., sodium and potassium) 2. Synthetic compounds (e.g., isopropanol and triethylene glycol) not found naturally in groundwater 3. Organic compounds (e.g., diesel‐range organics and gasoline‐range organics) While EPA presented a large dataset for the current state of the aquifers, they did not include any baseline data for ion concentrations. My study focused on baseline data for inorganic ions. Inorganic ions were chosen for study because historical data for organic compounds is less likely to exist, and baseline concentrations for synthetic compounds are not needed. Synthetic compounds do not occur in nature, so the baseline concentration is always assumed to be zero. Baseline data for ion concentrations were available for water wells, natural gas wells, and for surface water in the AOI. Although water wells are the focus of my study, data from natural gas wells and surface water have also been included in the cross section analysis (but not in the statistical analysis). Various parties, including educational institutions, government agencies and individuals have gathered and consolidated water quality data over many years. Major efforts, with some overlap, have been mounted by the Wyoming Water Development Office, the United States Geological Survey and the United States Environmental Protection Agency. The most useful baseline data sources for domestic and stock well water have been the following, in descending order: The State of Wyoming Water Resources Data System (WRDS). Funded by the Wyoming Water Development Office, WRDS functions as a clearing house for hydrological and climatological data, including groundwater quality data. Data can be queried from their website at http://www.wrds.uwyo.edu/wrds/dbms/hydro/sel.html. As an example of the type and amount of data available, a query for the parameter “PH WH LABORATORY” yielded 42 wells in the AOI. USGS papers, including the following: o Water Supply Paper 1375. Ground‐Water Resources of the Riverton Irrigation Project Area, Wyoming with a section on Chemical Quality of Ground Water. This source 1 The irrigation project has a long history, and the name of the project has been changed several times by the federal government. It has been called the Riverton Project, Riverton Withdrawal Area, part of the Missouri Basin Project, and the Midvale Irrigation District. 4 | P a g e
contains some data that are also in the WRDS database, and some data that are not in WRDS (Morris et al., 1959). o Water Supply Paper 1576‐I. Ground Water Resources of the Wind River Indian Reservation, Wyoming. Some older data is repeated from WSP 1375. WSP 1576‐I contains some data that are also in the WRDS database, and some data that are not in WRDS (McGreevy et al., 1969). The Wyoming State Engineer’s Office maintains records of permitted water wells, using a combination of a computer database (E‐Permit), scanned documents accessible from links in E‐ Permit, paper files, and microfiche. From the E‐Permit system, it is possible to query whether chemical analysis data exists for a particular well. With this information in hand, one can examine the scanned documents, paper files, or microfiche to determine which water quality parameters were analyzed. Figure 1. Location Map. Large lake at bottom center is Ocean Lake. Wells used for statistical analysis were within the area defined by the blue border. The cross section line is shown in blue. USGS Quadrangles shown include Morton, Lookout Butte, Pavillion Butte, Pavillion, Ocean Lake, Lost Well Butte, Mexican Pass, and Harris Bridge. Basemap data from WYGISC (Wyoming Geographic Information Science Center, 2013). 5 | P a g e
USGS National Water Information Service2. A query of NWIS based on the AOI yielded 30 wells. USGS Open File Report 92‐455, Water Resources of the Wind River Indian Reservation, Wyoming, contains water chemistry data in tabular form. The data are also stored in the National Water Information System (NWIS)‐‐Ground‐Water Site Inventory (GWSI) database. Another report, Water‐Resources Investigations Report 95‐4223, contains narrative discussion of the water resources of the reservation. Unfortunately, these two reports exclude the Riverton Withdrawal Area, in which the Pavillion Gas Field is located (Daddow, 1992; Daddow, 1996); however, the reports are useful in providing context. A report prepared by James Gores and Associates, in association with Wester Wetstein and Associates and Hinckley Consulting contains a summary of well locations, along with selected groundwater parameters. The report is entitled ‘Pavillion Area Water Supply Level 1 Study: Preliminary Interim Report for the Wyoming Water Development Commission’. The James Gores report contains ion concentration data, which appear to be derived from WRDS and EPA’s data. Additional databases were searched, but were not found to be useful for this study. For completeness, a list of these databases follows: o US EPA Water Quality Control Information System (STORET). STORET can be accessed at http://www.epa.gov/storet/. The system is split into “modern” and “legacy” data. A query of the “modern” data, based on the AOI and filtered for major inorganics brought up 178 sample locations, but none of them were wells; all of the data are for surface water, such as rivers and lakes. The “legacy” data likewise contained only surface water information. o USGS National Water Quality Assessment Program (NAWQA) is accessible at http://water.usgs.gov/nawqa/. A query for Fremont County on July 17, 2013 yielded ten wells with inorganic chemistry data. None of the wells are in the AOI. o USGS National Water‐Data Exchange (NAWDEX). NAWDEX no longer exists. o USGS OWDC Catalog of Information on Water Data. Catalog of Information on Water Data appears to no longer exist. DATA AVAILABILITY IN WRDS FOR THE AREA OF INTEREST (AOI) Because the most useful source of data was WRDS, this report concentrates on information obtained from that database. The data for the AOI in the WRDS database appears to have been gathered in four main periods: 1. Data collected from 1948 to 1953 2. Two datasets collected in 1960 and 1966 3. Data gathered in the 1970’s 4. Two datasets collected in the periods 1990‐1991 and 1998‐1999 The time period 1948 to 1953 coincides with major construction on the Third Division of the Midvale Irrigation Project and settlement of WWII veterans in the area. At this time, data were gathered to support the homesteading effort, including water quality data needed for drinking water wells. 2 (Formerly, USGS used a system called National Water‐Data Storage and Retrieval System (WATSTORE). WATSTORE redirects to NWIS at http://waterdata.usgs.gov/usa/nwis.) 6 | P a g e
The 1948 to 1953 water well data precedes gas development: Gas field appraisal was started with Gulf well Mae H. Rhodes 1, drilled to 11,000 feet in 1953 in Section 3, Township 3N 2E. Following this initial appraisal, gas field development was undertaken beginning in 1960, with well Ora Wells 14‐12, drilled in 1960 in Section 12, Township 3N 2E. Data availability for cations, anions, TDS and conductivity is shown in the following tables. Because hydroxide concentration can be calculated from pH (and vice‐versa), these two parameters are shown as a single column. The negative log of the hydrogen ion concentration, more commonly known as pH is a parameter of particular interest in this study. The pH of groundwater is typically between 6.0 and 8.5. It is atypical to find a pH values greater than 9 in natural groundwater (Hem, 1986); however, EPA measured several drinking water wells and stock water wells with high pH3. Table 1. Cation Data Availability for AOI Number of Samples ‐ Water Wells in AOI ‐ Cations Collection Dates Calcium Magnesium Sodium Potassium 1948 to 1953 32 32 39 33 1960 and 1966 3 3 3 3 1970's 0 0 43 0 1990/91 and 1998/99 6 6 6 6 Table 2. Anion Data Availability for AOI Number of Samples ‐ Water Wells in AOI ‐ Anions Collection Dates Sulfate Bicarbonate Carbonate 1948 to 1953 39 33 31 1960 and 1966 3 3 3 1970's 70 0 2 1990/91 and 1998/99 6 0 0 Hydroxide or pH Chloride 34 29 4 3 0 0 22 6 3 They also measured high pH in the water monitoring wells, however, those wells are not the focus of this study. 7 | P a g e
Table 3. TDS and Conductivity Data Availability for AOI Number of Samples ‐ Water Wells in AOI ‐ TDS & Conductivity Collection Dates Total Dissolved Solids Conductivity 1948 to 1953 27 37 1960 and 1966 4 0 1970's 70 0 1990/91 and 1998/99 0 22 Additional data exist in WRDS for the AOI; Tables 1‐3 present data relevant to the current study. There is interest in whether contamination could be occurring because of agricultural activities. There are baseline data for constituents such as nitrates that could be assessed for this purpose. STATISTICAL ANALYSIS OF IONIC CONSTITUENTS At the time of this writing, it has not been possible to analyze the variation in concentration of ions with depth, because depth information has not been collected for all the wells. In addition, because of the limited nature of this project, it was not possible to exhaustively analyze the bicarbonate and carbonate data. The difficulty in examining the bicarbonate/carbonate data is to reconcile values obtained by two different two calculation methods; improvements to the standard calculation method have recently been published by the USGS (Meyers, 2012). Meyers calls the two methods the “simple speciation method” and the “advanced speciation method.” The “simple speciation method” is the old method, and the “advanced speciation method” is the new method. In both methods, alkalinity, pH, and temperature are measured. Bicarbonate and carbonate are calculated from the alkalinity, pH, and temperature measurements. The new method is valid over a wider range of pH values than the old method. The two methods both yield useful data for broad‐brush analysis such as Stiff diagrams, but for detailed statistical analysis to be accurate, the same method needs to be used on all the data. New data (collected in 2009 thru 2011) from EPA were presented in terms of temperature, alkalinity and pH: hydroxide, carbonate and bicarbonate have been calculated from these parameters and used for the Stiff diagrams shown on the cross section; however, the old “simple speciation method” is not valid above pH 9.2, so the new “advanced speciation method” was used (for all data points). For detailed statistical analysis, this presents a problem, since the data are not directly comparable with the old data from WRDS. The old data in WRDS for bicarbonate and carbonate were likely calculated using the old “simple speciation method.” If enough data for alkalinity, pH, and temperature exist for the old data, it will be possible to recalculate the ion concentrations for the old data using the new method: this would make an “apples‐to‐apples” comparison possible. The constituents affected by the change in method are hydroxide, carbonate, and bicarbonate. Data for chloride, sulfate, calcium, sodium, potassium, pH, TDS and conductivity are not affected. An alpha of 0.05 was used to test for significance. 8 | P a g e
pH A histogram (Fig. 2) was made for pH showing data from three dates. There is a statistically significant increase in pH over time. Data were available in WRDS from two time periods. Recent measurements by the U.S. EPA were also used (DiGiulio et al., 2011). Data from 1948 to 1953 appear to be from WSP 1375 (Morris, 1959). Data from the 1990’s was collected by the USGS. The EPA data includes only water from drinking water and stock water wells: the two monitoring wells drilled by EPA are not included. The old data did not include wells as deep as the monitoring wells, so excluding the monitoring wells is appropriate. Figure 2. Bell Curve for pH Values in Drinking Water and Stock Water Wells. Monitoring wells are not included. The histogram provides some evidence of pH changes over time. Data from the 1940’s/50’s and from the 1990’s largely match. EPA data from 2009‐11 show a marked shift to higher pH values. A T‐test was used to compare the data in order to determine if the change was statistically significant. The results are summarized in Table 4. Table 4. Change in pH – p‐values T‐Test p‐values, compared to 1948 to 1953 WRDS Data 1990's WRDS data field 0.7546331 EPA data w/o monitoring wells 0.0000004 9 | P a g e
Possible source of systematic error It is possible for pH values to change between the field and the lab. A discussion of this phenomenon, as well as an analysis for 92 groundwater wells can be found in Field vs. Lab Alkalinity and pH: Effects on Ion Balance and Calcite Saturation Index (Shaver, 1993). It is assumed that the EPA pH values were measured in the field, and I am seeking confirmation from EPA on this point. The 1990’s data from WRDS have both field and lab values, but there only 6 lab values. This is not enough data for statistical testing, so the lab values are not included in the histogram or T‐test analysis. They do, however, provide insight as to the magnitude and direction of the change we could expect. The table below summarizes the change in pH for these six wells. The change from the lab to the field averages 0.3 pH units. The difference between the means of the 1948‐53 data and the recent EPA measurements is 0.9 pH units. This source of systematic error would not explain the entire change in pH. Difference in Direction of Station_ID pH, Field vs. Lab Difference '431046108313401 0.3 Field value higher '431215108435501 ‐0.7 Lab value higher 431252108290502 ‐0.2 Lab value higher '431441108360601 ‐0.5 Lab value higher '431532108364501 ‐0.4 Lab value higher '431811108270401 ‐0.3 Lab value higher It is not stated in WSP 1375 whether the 1948‐53 samples were tested in the field or in the laboratory. The WRDS database indicates that they are lab values, but I don’t know how they came to that conclusion. If the 1948‐53 values are lab values, they may be biased high: the true pH values at that time may have been even lower. This would increase the certainty of the conclusion that there has been a statistically significant change in pH. The error is in the “wrong direction” to try to explain away the difference by calling it systematic error. Sulfate By inspecting the Stiff diagrams on Cross Section 1, we can see that sulfate varies with depth: shallow water appears to have more sulfate than the deeper water wells and gas wells, with the exception of gas well 14‐10. If the entire dataset (unsorted for depth) is considered, there is no statistically significant change in concentration with respect to time. Table 5. Mean and standard deviation, sulfate. Standard Average SO4, Deviation SO4, mg/l mg/l 1948 to 53 WRDS data 1187 869 1970s WRDS 1067 1009 EPA data w/o monitoring wells 998 1002 10 | P a g e
Table 6. P‐values, sulfate. T‐Test p‐values, compared to 1948 to 1953 WRDS Data 1970s WRDS 0.516322 EPA data w/o monitoring wells 0.341376 Chloride From examination of the Stiff diagrams, chloride appears to increase with depth; however, there is not a statistically significant change with respect to time, if the entire dataset (unsorted for depth) is considered. Table 7. Mean and standard deviation, chlorides. 1948 to 53 WRDS data 1990'S WRDS EPA data w/o monitoring wells Standard Average Deviation Chlorides, mg/l Chlorides, mg/l 46 67 16 22 23 16 Table 8. P‐values for chloride. T‐Test p‐values, compared to 1948 to 1953 WRDS Data 1990'S WRDS 0.0621 EPA data w/o monitoring wells 0.0822 Calcium For calcium, sufficient data exist to compare the 1948‐53 dataset with the EPA dataset from 2009‐11. A statistically significant change in calcium concentration has occurred (p‐value = 0.03). Table 9. Average and Standard Deviation for Calcium Standard Average Deviation Calcium, Calcium, mg/l mg/l 1948 to 53 WRDS data 192 196 EPA data w/o monitoring wells 104 130 Magnesium For magnesium, sufficient data exist to compare the 1948‐53 dataset with the EPA dataset from 2009‐ 11. A statistically significant change in magnesium concentration has occurred (p‐value = 0.01). 11 | P a g e
Table 10. Average and Standard Deviation for Magnesium Standard Average Deviation Magnesium, Magnesium, mg/l mg/l 1948 to 53 WRDS data 62 71 EPA data w/o monitoring wells 22 40 Sodium For sodium, sufficient data exist to compare the 1948‐53 dataset with the EPA dataset from 2009‐11. There is not enough evidence to say that sodium has changed, when the entire dataset is compared (p‐ value=0.17). Table 11. Average and Standard Deviation for Sodium Average Sodium, mg/l 1948 to 53 WRDS data 314 EPA data w/o monitoring wells 389 Standard Deviation Sodium, mg/l 191 305 Potassium For potassium, sufficient data exist to compare the 1948‐53 dataset with the EPA dataset from 2009‐11. A statistically significant change in potassium concentration has occurred (p‐value = 0.01). Table 12. Average and Standard Deviation for Potassium Standard Average Deviation Potassium, Potassium, mg/l mg/l 1948 to 53 WRDS data 4 2 EPA data w/o monitoring wells 3 3 WELLBORE INTEGRITY ANALYSIS I downloaded well files from the Wyoming Oil and Gas Conservation Commission website, including well history narratives and cement bond logs. History narratives and cement bond logs were available for most of the wells. For each well, I read the well history narrative, with special attention to the cement jobs. I reviewed bond logs, and determined the top of cement from the Variable Density Log (VDL) waveforms. To obtain a bond log, the logging company lowers a sonde into the well. The sonde emits sound, and the sound penetrates the casing, cement, and formation. The sound echoes back, and the tool plots the echo waveforms as the VDL. Echoes of sound from these materials have different characteristics: 12 | P a g e
The pipe waves are regular and straight. The collars connecting each section of pipe are visible where pipe waves predominate. If the pipe is free to move (not cemented), the pipe waves will be the only waves present. Cement will dampen the vibration of the pipe, and attenuate the pipe waves. Lightweight cements will have less effect, and some pipe waves may still be present. Formation waves will be irregular in form, in contrast to the pipe waves, which are very regular. The formation is a natural material, and exhibits random variations in the attenuation of sound. If cement is “channeled,” both pipe waves and formation waves will be visible. Channeled cement refers to the condition where cement is present only partway around the circumference of the pipe. Channeled cement is insufficient to isolate the gas zone from the aquifer, because fluids from the gas zone can migrate through the channels. Figure 3. VDL section of bond log from Pavillion 41‐10, showing pipe waves (left of line) and formation waves (right of line). Figure 4. Cross section of pipe cemented in hole, showing channel. Annulus on left side is full of mud, while the annulus on the right side is cemented. I downloaded data from the WOGCC for the completion of each well, and examined the data to find the shallowest fractured completion in each well. CROSS SECTION VISUALIZATION I constructed a cross section showing the following: For domestic and stock water wells: o Depth and location along cross section o Stiff diagram showing water chemistry where available 13 | P a g e
For EPA monitoring well MW1: o Surface casing o Cemented intervals o Completion interval (blue) For gas wells: o Depth of surface casing o Cement integrity of surface cement o Cement integrity of longstring (production string) cement o No intermediate casing is shown. None of the wells in the cross section have intermediate casing. o Depth to top completion (frac) interval o A graphic suggestion of a hydraulic fracture, for the top frac interval only. The graphic shows the frac as a “penny shaped fracture” of 120 feet radius, but the fracture dimensions are unknown. The graphic is centered at the top perforation. o Because this study is focused on the shallow subsurface, wells were truncated at 2400 feet elevation above mean sea level (MSL). Depending on the elevation at the wellhead, the exact depth below ground surface (BGS) varies, but 2400 feet elevation MSL is about 3000 feet depth BGS. Surface elevations for wellheads vary, but are around 5400 feet. o Stiff diagrams for water analysis. Water analyses were retrieved from the WOGCC website. Important sources of surface recharge to shallow aquifers, such as canals, drain ditches, and ponds, are shown as graphics to indicate their location along the line of section. Formation contacts are not shown: the entire section is within the Wind River Formation, or the overlying alluvial materials. SUMMARY Water quality parameters, including pH and ion concentrations, were analyzed for domestic and stock water wells in and near Pavillion Gas Field. I found significant change for pH, calcium, magnesium, potassium. I was unable to find a significant change in sulfate or chloride concentration4. Time did not permit a statistical analysis of bicarbonate and carbonate ion concentration. A cross section including water and gas wells, as well as sources of surface recharge, is attached. The cross section shows wellbore integrity issues with seven of fifteen gas wells. Cement is missing over long sections of several wells. Cement is essential to confine fracturing fluid and gas to the production zone: cement “squeeze” repairs are needed. Water composition varies in this complex aquifer system. With some exceptions, it appears that the deeper aquifers in the area have better quality water. The Stiff diagram will be “fatter” if there are more dissolved solids in the water, and “skinnier” if there are fewer dissolved solids. The deeper aquifer wells have a similar mineral composition as the water in the gas reservoir, but a “skinnier” diagram for aquifer wells indicates significantly less TDS in the aquifers as compared to the gas reservoir. It appears that sulfate is more prevalent in the shallow aquifers, and the deeper water has fewer sulfates. 4 EPA noted a change in chloride concentration in their analysis of the monitoring wells. The monitoring wells were not used in my analysis: only drinking water and stock water wells were included. 14 | P a g e
ACKNOWLEDGEMENTS I wish to express my appreciation to my advisor, Dr. Patricia Colberg, for building my technical expertise, and for her mentoring on this project, and Dr. David Bagley for his clear explanations of water chemistry topics, and for facilitating access to software resources. I wish to thank EPSCoR for funding the work and providing a research project opportunity I would not have had otherwise. REFERENCES CITED Daddow, R. L. 1992. Ground‐Water and Water‐Quality Data through 1991 for Selected Wells and Springs on the Wind River Indian Reservation, Wyoming. Open File Report 92‐455. United States Geological Survey, Denver, CO. Daddow, R. L. 1996. Water Resources of the Wind River Indian Reservation, Wyoming. Water‐ Resources Investigations Report 95‐4223. United States Geological Survey, Denver, CO. DiGiulio, D.C., Wilkin, R.T., Miller, C., and Oberley, G. 2011. Draft Investigation of Ground Water Contamination near Pavillion, Wyoming. EPA 600/R‐00/000. U.S. Environmental Protection Agency, National Risk Management Research Laboratory, Ada, OK. Environmental Protection Agency FTP Site. ftp://ftp.epa.gov/r8/pavilliondocs/RawLabData/. Accessed June 2013. GeoCommunicator Land Survey Information System. http://www.geocommunicator.gov/GeoComm/lsis_home/home/. Site accessed June, July and August 21, 2013. Hem, J.D. 1986. Study and Interpretation of the Chemical Characteristics of Natural Water. Water Supply Paper 2254. United States Geological Survey, Alexandria, VA. McGreevy, L.J., Hodson, W.G., Rucker, S.J. Ground Water Resources of the Wind River Indian Reservation, Wyoming. Water Supply Paper 1576‐I. United States Government Printing Office, Washington. 1969. Morris, D.A, Hackett, O.M., Vanlier, K.E., Moulder, E.A., and Durum, W.H. 1959. Ground‐Water Resources of the Riverton Irrigation Project Area, Wyoming with a section on Chemical Quality of Ground Water. Water Supply Paper 1375. United States Government Printing Office, Washington. Meyers, D.N. 2012. Office of Water Quality Technical Memorandum 2012.05: Replacement of the Simple Speciation Method for Computation of Carbonate and Bicarbonate Concentrations from Alkalinity Titrations. United States Geological Survey, Alexandria, VA. Petty, J.C. 1994. Water Quality and Associated Best Management Practices on the Ocean Lake Hydrologic Unit Area, Fremont County, Wyoming. Masters Thesis, University of Wyoming, Laramie, WY. Sample Locations for Mapping. Excel File. Received from US EPA, Region 8, June 17, 2013. 15 | P a g e
Shaver, R.B. 1993. Field vs. lab alkalinity and pH: Effects on ion balance and calcite saturation index. Groundwater Monitoring and Remediation, Spring 1993. National Ground Water Association, Westerville, OH. Water Resources Data System. http://www.wrds.uwyo.edu/wrds/dbms/hydro/sel.html. Site accessed June, 2013. Worman, B.N. and Quillinan, S.A. 2011. Surface Geology of the Pavillion Groundwater Investigation (map). Wyoming State Geological Association, Laramie, WY. Wyoming State Engineer’s Office FTP Site. ftp://seoftp.wyo.gov/geolibrary_data/SEOwells.zip. Accessed June, 2013. Wyoming State Engineer’s Office microfiche files. 122 West 25th Street, Herschler Building, Cheyenne, Wyoming 82002. Accessed June 2013. Wyoming Geographic Information Science Center. http://www.uwyo.edu/wygisc/. Accessed June, July and August 21, 2013. Wyoming Oil and Gas Conservation Commission Website. http://wogcc.state.wy.us/. Accessed June, July and August 2013. 16 | P a g e
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