ML20054F301
| ML20054F301 | |
| Person / Time | |
|---|---|
| Issue date: | 05/31/1982 |
| From: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
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| ML20054F289 | List: |
| References | |
| REF-WM-5 WM-8203-DRFT, NUDOCS 8206160044 | |
| Download: ML20054F301 (31) | |
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DRAFT STAFF TECHNICAL POSITION PAPER l
l HYOROGE0 LOGIC CHARACTERIZATION OF URANIUM SOLUTION MINE AND MILL TAILINGS DISPOSAL SITES WM-8203 Uranium Recovery Licensing Branch U.S. Nuclear Regulatory Corr. mission May 1982 8206160044 820601 PDR WASTE WM-5 PDR J
I TABLE OF CONTENTS Page No.
1.
INTRODUCTION...........................................
1 2.
SUPPORTIVE DOCUMENTS...................................
1 3.
STAFF P0SITION.........................................
2 3.1 Data and Information..............................
3 3.1.1 Surface Features........................
3 3.1.1.1 Topography.........................
3 3.1.1.2 Soils..............................
3 3.1.1.3 Surface Water......................
4 3.1.2 Subsurface Features.....................
4 3.1.2.1 Geology............................
4 3.1.2.2 Hydrostratigraphy..................
4 3.1.2.3 Seismicity.........................
5 3.1.2.4 Groundwater........................
5 3.1.2.5 Hydraulic Properties...............
5 3.1.2.6 Hydrogeochemical Properties........
6 3.2 Methods of Investigation..........................
6 3.2.1 Topography..............................
6 3.2.1.1 Surface Features...................
6 3.2.1.2 50i1s..............................
6 3.2.1.3 Surface Water......................
6 3.2.2 Subsurface Features.....................
7 3.2.2.1 Geology, Hydrostratigraphy, and Seimsmicity......................
7 3.2.2.2 Groundwater........................
7 3.2.2.3 Hydraulic Properties...............
7 3.2.2.4 Hydrogeochemical Information.......
8 3.3 Submittal of Data.................................
8
TABLE OF CONTENTS (continued)
Page No.
APPENDIX A APPLICATIONS FOR BOREHOLE GE0HPYSICS IN DETERMINING SITE CHARACTERISTICS FOR URANIUM MILL TAILING DISPOSAL AND SOLUTION MINING SITES........................................
A-1 1.
INTRODUCTION..........................................
A-1 2.
TYPES OF GEOPHYSICAL L0GS..............................
A-1 2.1 Nuclear Logs......................................
A-1 2.1.1 Natural Gamma Log.......................
A-1 2.1.2 Gamma Gamma Log.........................
A-2 2.1.3 Neutron Epithermal Neutron Log..........
A-2 2.2 Fluid and Mechanical Logs.........................
A-3 2.2.1 Caliper Log.............................
A-3 2.2.2 Temperature Log............
A-3 2.2.3 Flow Log................................
A-4 2.3 Electric Logs.....................................
A-4 3.
DESIGNING A GEOPHYSICAL LOGGING PROGRAM FOR SITE SUITABILITY ANALYSES...................................
A-5 4.
REFERENCES (APPENDIX A)................................
A-7 APPENDIX B DETERMINATION OF HYDRAULIC PROPERTIES........
B-1 1.
INTRODUCTION...........................................
B-1 2.
HYDRAULIC GRADIENT.....................................
B-1 3.
SATURATED HYDRAULIC CONDUCTIVITY.......................
B-1 3.1 Laboratory Methods................................
B-2 3.2 Field Methods.....................................
B-3 3.2.1 Discharging and Recovery Well Methods...
B-3 3.2.1.1.
Theim Equilibrium Method...........
B-3 3.2.1.2 Theis Non-equilibrium Method.......
B-4 3.2.1.3 Hantush-Jacob and Hantush Modified Leaky Artesian Methods...........
B-5
- 3. 2.1. 4 Neumann-Witherspoon Method.........
B-6
TABLE OF CONTENTS (continued)
Page No.
3.2.2 Injection Tests.........................
B-7 3.2.2.1 Packer Tests.......................
B-8 3.2.2.2 Slug Tests and Bail Tests..........
B-8 3.3 Conclusions and Recommendations Regarding Measurements of Saturated Hydraulic Conductivity..
B-8 4.
UNSATURATED HYDRAULIC CONDUCTIVITY.....................
B-10 5.
REFERENCES (APPENDIX B)................................
B-11
1.
INTRODUCTION This position paper is intended as a supplement to U.S. Nuclear Regulatory Commission, Regulatory Guides, " Standard Format and Content of License Applications, Including Environmental Reports, for In Situ Uranium Solution Mining" No. 3.46, and " Preparation of Environmental Reports for Uranium Mills", No. 3.8, to' provide more specific guidance on hydrogeologic characterization for site suitability studies.
This guidance results from operating experience at several uranium mill tailings disposal sites and solution mining facilities, and reflects approaches that are acceptable to the NRC staff.
This paper does not attempt to list all sources or methodologies available for obtaining hydrogeologic data, and reasonable alternatives will be considered on a case by case basis.
2.
SUPPORTIVE DOCUMENTS Prior to develpoment of an application for a uranium mill or in situ solution mining facility, the applicant should review the following documents which can be obtained from the Nuclear Regulatory Commission upon request:
1.
U.S. Nuclear Regulatory Commission, Regulatory Guide 3.46,
" Standard Format and Content of License Applications, Including i
Environmental Reports, for In Situ Uranium Solution Mining."
2.
U.S. Nuclear Regulatory Commission, Rules and Regulations, Title 10, Code of Federal Regulations, particularly Parts 20, 40, and 51.
3.
U.S. Nuclear Regulatory Commission, Regulatory Guide 3.8,
" Preparation of Environmental Reports for Uranium Mills" and Regulatory Guide 3.5, " Standard Format and Contents of License Applications for Urenium Mills."
4.
U.S. Nuclear Regulatory Commission, Regulatory guide 3.11,
" Design, Construction, and Inspection of Embankment Retention Systems for Uranium Mills."
5.
U.S. Nuclear Regulatory Commission, " Staff Branch Position On Explorations for Design and Evaluation of Uranium Mill Tailings Retention Systems," Uranium Recovery Licensing Branch.
6.
U.S. Nuclear Regulatory Commission, Regulatory Guide No. 4.15,
" Quality Assurance for Radiological Monitoring Programs (Normal Operations) - Effluent Streams and the Environment."
7.
U.S. Nuclear Regulatory Commission, Staff Technical Position Paper (WM 8101), " Design, Installation, and Operation of 1
Natural and Synthetic Liners at Uranium Recovery Facilities, "
Uranium Recovery Licensing Branch.
8.
U.S. Nuclear Regulatory Commission, Staff Technical Position Paper (WM 8102), " Groundwater Monitoring at Uranium In Situ Solution Mines."
9.
U.S. Nuclear Regulatory Commission, Draft Regulatory Guide ES 114-4, " Guidelines for Groundwater Monitoring at Uranium In Situ Solution Mines" (to be issued late 1982).
10.
U.S. Nuclear Regulatory Commission, Draft Regulatory Guide ES 115-4, " Guidelines for Modeling Groundwater Transport of l
Radioactive and Non-radioactive Materials at Tailings Disposal Sites" (to be issued late 1982).
11.
U.S. Nuclear Regulatory Commission, Regulatory Guide 4.14, Revision 1, " Radiological Effluent and Environmental Monitoring at Uranium Mills."
3.
STAFF POSITION Site suitability for tailings disposal should be an optimization to the maximum extent reasonably achievable, in terms of the following:
remoteness from populated areas; hydrogeologic and other natural conditions as they contribute to immobilization and isolation of contaminants from usable groundwater sources; and potential for minimizing erosion, disturbance, and dispersion by natural forces.
Steps should be taken to eliminate, or minimize to the maximum extent reasonably achievable, seepage of radioactive and non-radioactive materials from tailings disposal impoundments into groundwater, and existing ground water supplies should not be deteriorated such that current or potential use classifications are changed.
Site suitability for a uranium in situ solution mine should be an optimization, to the maximum extent reasonably achievable, in terms of:
hydrogeologic and other natural conditions as they contribute to immobilization and confinement of lixiviant within the ore zone being mined.
Uranium mill tailings disposal facilities and solution mines should not be located in areas where faults, improperly abandoned exploration holes, or other hydrogeologic features could promote the seepage or excursion of wastes er mining fluids.
2
i This position paper lists specific types of information that should be gathered for evaluating adequately the suitability of a hydrogeologic environment for uranium mill tailings disposal or in situ solution mining.
Detailed hydrogeologic evaluations at the site should include those areas within and adjacent to site boundaries that could be affected by mine/ mill construction or operation.
Hydrogeologic data for the site 4
region are generally less detailed. A descriptiori of the site region should at least include discussion of regional flow systems (recharge, discharge, lateral and vertical flow, etc.,) of those aquifers that could be impacted by operations.
Specific and detailed guidance on additional hydrochemical information needed for modeling seepage from uranium mill tailings disposal sites is l
presented in U.S. Nuclear Regulatory Commission Draft Regulatory Guide ES-115-4, " Guidelines for Modeling Groundwater Transport of Radioactive and Non-radioactive Materials at Tailings Disposal Sites" (to be issued late 1982).
3.1 Data and Information The following outline lists the types of information and areas where hydrogeologic and related data should be gathered for evaluating adequately the suitability of a location for uranium mill tailings disposal or in situ solution mining.
3.1.1 Surface Features 3.1.1.1 Topography (a)
Influence of topography on water table configuration (b) Aquifer exposure along cliffs, canyons, etc.
(c)
Influence of elevation and slope on recharge and runoff (d) Other natural or man-made surface features such as rivers, streams, ponds, mines and other facilities that could affect groundwater quality or flow.
3.1.1.2 Soils (a) Soil surveys and classifications including permeabilities and l
infiltration rates.
(b) Hydrogeochemical and hydraulic properties of soils including foundation and subgrade materials used in earthen embankments, so that contaminant migration can be predicted during and after the life of the operation.
Properties include neutralizing capacity, distribution coefficients (Kd's) for specific ions (sorption characteristics), clay mineral identification, delineation of the 3
1 2
_ - -. -, _ -, ~,,,. -,
,.n
leachable ions under specific levels of pH, moisture content, and saturated and unsaturated hydraulic conductivities.
(NOTE: This type of data pertains primarily to uranium mill tailings disposal and evaporation pond sites.)
3.1.1.3 Surface Water (a) Delineation of drainage areas, seeps, springs, ponds, and lakes.
(b) Hydrologic budget for the surface drainage area and tailings impoundments (precipitation, evaporation, infiltration rates, etc..).
(c) Flow rates and directions, and flooding potentials.
(d) Surface water users that could be affected up and down gradient of the site, indicating source, use, quality, and potential impacts.
(e) Comprehensive background water quality analysis of surface water bodies on site and at off site locations that could possibly be affected.
(NRC Staff Technical Position Paper WM-8102, " Groundwater Monitoring at Uranium In Situ Solution Mines", NRC Draft Regulatory 114-4, " Guidelines for Groundwater Monitoring at Uranium In Situ Solution Mines" (to be issued late 1982), and NRC Regulatory Guide 4.14, " Radiological Effluent and Environmental Monitoring at Uranium Mills", provides specific guidance in obtaining surface and groundwater baseline data.) The water should be analyzed for major and minor chemical indicators, radiological species, and any other indicators of special concern to the particular operation or hydrologic system.
Surface water samples should be analyzed for total and dissolved concentrations.
3.1.2 Subsurface Features 3.1.2.1 Geology Mapping of faults, fractures and joint planes, and buried stream bed channels; strike, dip and plunge of beds determined; lithologic features shown in plan view and in cross section including the ore zone (s) and tailings disposal site.
3.1.2.2 Hydrostratigraphy (a) Regional and site specific hydrostratigraphic section(s) delineating aquifers, aquicludes, and aquitards.
At sites being considered for solution mining, it is imperative that the thicknesses and continuity of the ore zone (s) and confining units be fully evaluated.
4
(b) Water levels in the confined and unconfined aquifers determined and water table and potentiometric maps prepared. Water levels should be determined from a fixed measuring points related by leveling to a nearby fixed reference point based on a standard datum such as mean sea level.
Vertical and horizontal groundwater hydraulic gradients and flow directions should be determined.
(c) Delineation of factors affecting groundwater levels such as topography, pumping, evapotranspiration, local and regional sources of recharge and discharge, and seasonal and long-term climatic influences.
3.1.2.3 Seismicity (a) Regional and site specific tectonic features related to seismic events.
(b) Regional and local epicenter maps.
3.1.2.4 Groundwater (a) Groundwater users within approximately 2 miles of site boundaries indicating quantities used, potential use(s), quality, source aquifers, registered and unregistered water wells.
(b) Comprehensive background water quality analysis, on and off site, of aquifers possibly affected (NRC Staff Technical Position Paper WM-8102, " Groundwater Monitoring at In Situ Solution Mines," NRC Draft Regulatory Guide 114-4, " Guidelines for Groundwater Monitoring at Uranium In Situ Solution Mines" (to be issued late 1982), and NRC Regulatory Guide 4.14, " Radiological Effluent and Environmental Mor.itoring at Uranium Mills" provide specific guidance in obtaining l
- .ater quality baseline data).
The water should be analyzed for najor and minor chemical indicators, radiological species, and any ather indicators of special concern to the particular operation or hydrologic system.
l 3.1.2.5 Hydraulic Properties t
l Hydraulic properties of the aquifers - directional transmissivities and hydra;1ic conductivities, leakance coefficients and hydraulic conductivities of confining layers, pore velocity, total and effective porosities, storage coefficients, racharge and discharge boundaries, and bulk density estimates.
(NOTE:
For in situ solution mining operations, the rate of vertical movement of lixiviant through confining bed (s) should be computed for average and worse case hydrogeologic and operating I
conditions.)
I i
5
{
l
3.1.2.6 Hydrogeochemical Properties Hydrogeochemical and hydraulic properties of potentially affected hydrostratigraphic units, so that contaminant migration can be predicted during and after the life of the operation.
Properties include neutralizing capacity, distribution coefficients (Kd's) for specific ions (sorption characteristics), clay mineral identification, decay constants, delineation of the leachable ions under specific levels of pH, moisture content, and saturated and unsaturated hydraulic conductivities.
(NOTE:
This type of data pertains primarily to uranium mill and tailings disposal and evaporation pond sites.)
3.2 Methods of Investigation The following outline lists some of the acceptable methods and general sources for obtaining the hydrogeologic and related data pertaining to the areas listed above.
3.2.1 Surface Features 3.2.1.1 Topography (a) Site surveys (b)
U.S. Geologic Survey Topographic maps 3.2.1.2 Soils (a) Soil sampling and laboratory testing (permeability tests, sieve analysis, dispersivity tests, batch or column tests, laboratory chemical analysis, and mineral identification).
(b)
U.S. Soil Conservation Service, and U.S. Geologic Survey reports and maps 3.2.1.3 Surface Water (a) Water quality data obtained by the applicant (NRC Staff Technical Position Paper WM-8102, " Groundwater Monitoring at Uranium In Situ Solution Mines", NRC Draft Regulatory Guide 114-4, " Guidelines for Groundwater Monitoring at Uranium In Situ Solution Mines" (to be issued late 1982), and NRC Regulatory Guide 4.14, " Radiological Effluent and Environmental Monitoring at Uranium Mills" provide specific guidance in obtaining surface and groundwater quality j
baseline data.)
i (b) Site specific hydrologic data collected by the applicant (stream gauging, precipitation, evaporation, etc.)
i 6
i I
i
(c)
U.S. Geologic Survey topographic maps, Water Resource Investigations and Reports, annual stream flow records, "NAWDEX" and "WATSTORE" computer data retrieval systems (d)
U.S. Meteorologic Reports (from NOAA)
(e) State Engineer or Water Resources Department reports and records 3.2.2 Subsurface Features 3.2.2.1 Geology, Hydrostratigraphy and Seismicity (a) Lithologic and bore hole geophysical logs (additional background information and reference sources on borehole geophysical logging are presented in Appendix A).
(b)
U.S. Geologic Survey maps, Water Resources Investigations and Reports; State Geologic Reports; and State Engineer and Water Resource Department Reports (c) Regional Earthquake Epicenter Map (Algermission, S.T., and Perkins, D.M., "A Probabilistic Estimate of Maximum Acceleration in the Rock in the Contiguous United States,"
U.S. Geologic Survey Open File Report 74-716 1976) 3.2.2.2 Groundwater (a) Water quality and potentiometric data collected by the applicant (NRC Staff Technical Position Paper, WM-8102, " Groundwater Monitoring at Uranium In Situ Solution Mines", NRC Draft Regulatory Guide 114-4, " Guidelines for Groundwater Monitoring at Uranium In Situ Solution Mines" (to be issued late 1982), and NRC Regulatory Guide 4.14, " Radiological Effluent and Environmental Monitoring at Uranium Mills" provides specific guidance in obtaining surface and groundwater quality baseline data.)
(b)
U.S. Geologic Survey maps, Water Resource Investigations and Reports, and "NAWSEX" and "STURST" data retrieval systems l
(c) State engineer and Water Resource Department Reports and records of groundwater users.
(d) Regional water level elevation maps 3.2.2.3 Hydraulic Properties
(
(a) Site specific aquifer pumping tests, and field and laboratory j
permeability tests (Some acceptable methods for determining hydraulic properties of saturated and unsaturated rock units and reference sources are presented in Appendix B.)
7 l
(b)
U.S. Geologic Survey Maps and Water Resource Investigations and Reports; and State Water Resource Department reports 3.2.2.4 Hydrogeochemical Information (a)
Ion exchange capacity and dispersion, permeability, mineral identification, diffusion and distribution coefficients for specific hydrostratigraphic zones should be determined generally in the laboratory using cation exchange, column, and batch tests from samples obtained f om the proposed site.
(b) Published values for hydrogeochemical parameters, found in hydrologic studies completed by consultants for industry, universities, or government, can in some cases be used.
- However, these values should be applied cautiously and application of this data to a specific site should be justified and its limitations discussed.
3.3 Submittal of Data Data pertaining to the various areas of hydrogeologic site characterization discussed above, as well as details on methods used to obtain data, should be submitted in the Environmental Reports discussed in U.S. Nuclear Regulatory Guides 3.8, " Preparation of Environmental Reports for Uranium Mills," and 3.46, " Standard Format and Content of License Applications, Including Environmental Reports, for In Situ Uranium Solution Mining".
8
APPENDIX A APPLICATIONS OF BOREHOLE GEOPHYSICS IN DETERMINING SITE CHARACTERISTICS FOR URANIUM MILL TAILINGS DISPOSAL AND SOLUTION MINING SITES 1.
INTRODUCTION Delineation of hydrostratigraphic units at uranium mill tailings disposal and uranium in-situ solution mine sites is of key importance in site characterization.
Standard methodologies delineating variations in subsurface permeabilities of specific hydrostratigraphic units dominating local flow systems includes drilling test holes and analyzing drilling rates, returned chip samples, core samples, drilling fluid volume returns, and pump test results.
Unfortunately, relatively thin but important units of high permeability may not be recognized using these techniques.
Chip samples are difficult to analyze and often mixed, core recovery is generally not good in low density formations, and unless extremely good judgement is exercised, pump tests are usually conducted over a relatively large vertical column of subsurface material providing an average overall hydraulic conductivity.
Critical units of high permeability can generally be delineated through borehole geophysical logs used in conjunction with other hydrogeologic information, particularly undisturbed geologic cores or pitcher samples.
The reader is referred to Keys and MacCary (1971) for a description of geophysical techniques as related to water resource investigations.
2.
TYPES OF GEOPHYSICAL LOGS AND THEIR APPLICATIONS In general, all geophysical logs provide some information towards determining subsurface hydrostratigraphy and associated groundwater flow systems, but some logs provide more meaningful data depending on local geology and borehole construction.
A description of common geophysical logs are presented below.
2.1 Nuclear Logs Nuclear or radiation logs measure radiation emitted from the nucleus of an atom.
They have distinct advantages over most other geophysical logs in that they can derive information from cased as well as open holes filled with any type of fluid.
The most common nuclear logs are natural gamma, gamma gamma, and neutron epithermal neutron.
The primary functions of these logs are to determine variations in lithology, density, moisture content, and porosity within borehole materials.
2.1.1 Natural Gamma Log The record of natural gamma radiation emitted by borehole materials is i
called a natural gamma or gamma ray log.
Its primary uses are for identifying lithology (typically clay units or uranium ore bearing zones) l l
l A-1 l
and to aid in stratigraphic correlation.
The logs may be obtained from open or cased, liquid or air-filled holes.
Heavy radioactive elements are generally concentrated in clays by ion exchange and adsorption, therefore, clay units generally show high gamma intensities making them good stratigraphic markers for correlation.
Because clay reduces percolation inhibiting vertical migration of contaminants. it is very-important to determine the presence, and lateral and vertical continuity-of homogeneous clay units in assessing a site of uranium mill tailings disposal or in situ solution mining.
2.1.2 Gamma Gamma Log The gamma gamma log is produced from an induced radiation tool recording gamma photons that have been back-scattered and attenuated within the borehole and surrounding rocks.
These logs are used for identifying lithology and for measuring bulk density and porosity of borehole formations.
Gamma photons undergo Compton scattering with orbital electrons from the borehole environment.
Due to photon scattering and subsequent lowering of energy levels, less radiation is detected by the sensor in media of high electron density and conversely higher back-radiation is detected in high porosity zones.
This relationship is used to delineate lithologies of different densities.
The gamma gamma log measures continuous variations in bulk density, and is very valuable in assessing locations of permeable hydrostratigraphic units.
Unfortunately, the gamma gamma log has a small radius of investigation (zone from which information is derived) so the tool is best suited for use in small diameter boreholes where caving is not a problem.
Borehole rugosity affects responses to all radiation tools due to the irregularity of materials in the zone of investigation (borehole fluid vs. surrounding wall rock).
The gamma gamma log is most susceptible to rugosity and should be run decentralized within the borehole so that scurce and detector are deriving information from wall rock and not just the borehole fluid medium.
2.1. 3 Neutron Epithermal Neutron Log The energy of neutrons emitted by the neutron epithermal neutron log probe is modified by elastic collisions with borehole elements.
Neutrons are slowed most effectively by hydrogen nuclei which have approximately the same mass as the neutron.
Abundant hydrogen will cause a large energy loss to the emitted neutrons which is detected by the probe.
Conversely, less hydrogen is detected as a smaller energy loss.
Because most natura! hydrogen is in water, the activity registered on the log is inversely proportional to the moisture content of unsaturated media and the porosity of material below the water table (Davis and DeWist, 1966).
A-2
s Dynamic seepage relationships may also be monitored by running neutron logs in the same borehole at various-times and comparing variations in moisture at different zones and times.
The neutron epithermal neutron log is commonly.a key indicator for permeable hydrostratigraphic units within the borehole.
This log has a relatively large radius of investigation and is very sensitive to variations in grain size distribution ind the presence of fractures which may have otherwise gone undetected.
Radiation logs are based upon a statistical return response of photons and neutrons as a function of logging speed.. When the objective of the logging program is to delineate small-scale hydrostratigraphic units which may dominate groundwater flow systems, it is important that the logging speed be slow allowing for a statistically significant return of raditaion to the detector.
A maximum logging speed of 15 feet per minute is commonly used to give the degree of detail necessary for this type of assessment.
Faster logging speeds tend to give an average response over a larger zone of borehole, masking individual hydroscratigraphic units and consequently, decreasing the effectiveness of the logging operation.
2.2 Fluid and Mechanical Logs In addition to aiding in determining lithologic parameters, well logs can also be used for defining the character and movement of water in boreholes and formations.
Characteristics of well bore fluids can be measured directly, where as formation fluids may only be characterized from geophysical logs.
Logs measuring fluid parameters are important in assessing subsurface hydrostratigraphy because they can locate aquifer zones with varying water chemistries.
Mechanical logs can show relative movement of water within boreholes giving an indication of hydraulic potentials within aquifers or groundwater flow systems at a site.
2.2.1 Caliper Log The caliper log is a continuous record of the average diameter of a borehole.
Its primary use is to evaluate the environment, or borehole rugosity, so that other logs can be corrected for hole diameter variations.
The caliper log is also used to provide information on lithology showing zones of incompetence where breakouts occur.
Sensitive caliper logs also indicate the presence of fractures which may constitute flow paths for contaminants.
2.2.2 Temperature Log Temperature logs record the thermal gradient of borehole fluids using a single sensor or thermistor.
The fluid temperature is representative of rock conductivities as long as fluid in the well is in thermal equilibrium with adjacent rocks, and there is no vertical circulation of fluid within the borehole.
Vertical movement of borehole fluid causes mixing of water of varying temperatures which is recorded as a A-3
homogeneous water temperature.
Conversely, influxes or effluxes of water cause rapid temperature changes at specific zones within a borehole.
Such zones can be interpreted to give some indication of migratory paths for contaminants in event seepage or excursions occur.
2.2.3 Flow Log
~
Geophysical logs indicating fluid flow are similar to temperature logs in that they are used for determining hydraulic potentials. They aid in identifying recharge and discharge areas, and head differences between hydrostratigraphic units, which are important parameters to be determined at waste disposal sites.
In-hole flow is commonly measured with an impeller flow meter (.esigned to measure vertical movements.
The direction of fluid movement indicates varying head potentials within aquifer zones and gives an indication of relative aquifer permeabilities.
If water samples are to be taken for water quality analysis, it is important to determine the occurrance of vertical mixing.
In very shallow holes (less than 100 feet deep), or in holes that are completely cased with no openings, fluid and mechanical logs may not be very useful.
Very little gcothermal gradient exists within 100 feet of the subsurface and temperature anomalies usually are not significant enough to allow for flow system identification with the temperature log; although a high temperature contaminant in the near surface could be easily identified.
A completely cased borehole does not allow interaction between hydrostratigraphic units or vertical circulation and a fluid flow log would not be useful in such a case.
In general, when a decision is necessasry concerning which fluid or mechanical logs should be run, the caliper log has the highest priority because of its importance in interpreting other logs.
It is best to conduct all geophysical logging in an open borehole if possible.
This maximizes sonde responses as well as options in selecting tools to be run.
In all open holes, a caliper log is a must when radiation logs are to be interpreted.
2.3 Electric Logs In general, electric logs provide information about lithology, hydrostratigraphic unit thickness, fracture location and fluid movement.
They are a measure of natural potentials and resistivities and can only be run in open (uncased) holes that are filled with a conducting fluid, such as mud or water.
There are many types of electric logs which can be run in boreholes, the choice is dependent upon the purpose of the survey.
The spontaneous potential log is a record of the small differences in voltage (measured in millivolts) that develop at the contacts between borehole fluid and borehole media, usually shale or clay.
Other electric logs (resistance and resistivity logs) consist of single point and differential resistance, short normal, long normal, lateral, microlog, microfocus, and guard or lateral resistivity log.
Each of these devices has a specific application depending on lithology, depth of mud invasion, A-4
and area of interest within the borehole.
It is not necessary to run all of these electric logs to determine variations in lithology, aquifer locations, and relative conductivities of porous media.
The petroleum industry has developed electric logging techniques for use in evaluating the zone invaded with muds due to drilling holes under high pressure.
Since this is commonly not the case in a test hole, the long normal and lateral logs need not be run to determine engineering properties.
For more information on various types of resistivity logs, it is suggested the reader check the Schlumberger manuals (1972 and 1977), Guyod (1966),
and Pirson (1963).
3.
DESIGNING A GEOPHYSICAL LOGGING PROGRAM FOR SITE SUITABILITY ANALYSES The number of boreholes to be geophysically logged and the selection of specific logs for hydrostratigraphic analysis at a site is dependent upon general site geology and complexity of the site's hydrostratigraphy.
A site composed of unconsolidated sediments requiring casing in all boreholes would not be as amenable to electric or fluid-flow logging as a site composed of consolidated rock which would hold an open borehole.
In general, the preferable suite of radiation logs is natural gamma, gamma gamma, and neutron epithermal neutron.
Temperature, caliper, and electric logs, usually SP and single point resistance, should also be run.
Unless logs are taken entirely within casing, the caliper log needs to be run whenever radiation tools are used.
In cased holes, the caliper log will not yield borehole rugosity information, but is useful in examining casing for pinching, swelling, or broken areas.
The objective of geophysical logging is to provide a continuous sampling of subsurface hydrostratigraphic units at a site for variations in density and porosity. Once the hydrostratigraphy has been delineated further logging would be necessary only to determine if any geologic structure off-sets, or in any way effects, general subsurface characteristics:
The optimum geophysical well logging program includes:
1.
Collecting a continuous core or extracting samples systematically throughout the length of each borehole or boreholes representative of the area.
2.
Maintaining a constant hole diameter (four inches) enabling entry of geophysical probes but not so large as to decrease the radius of investigation, and to eliminate the difficulties of interpreting logs from multidiameter holes.
3.
Obtaining logs in an open hole without casing.
4.
Removing drilling fluid from the borehole and borehole walls before commencing logging.
A-5 I
l
5.
Logging though mud or revert rather than casing the hole in cases when the hole will not stand open with fresh water.
6.
Installing plastic casing which is cemented to the formation before logging if casing is required during drilling as a result of hole instability.
A-6
REFERENCES (APPENDIX A)
Davis, S.
N., and DeWeist, R. J. M., 1966, Hydrogeology: John Wiley &
Sons, Inc., 463 pp.
- Guyod, H., 1966, Interpretation of Electric and Gamma Ray Logs in Water Wells:
Log Analysis, vol. 6, no. 5, pp. 29-44.
Keys, W. S., and MacCary, C. M.,1971, Application of Borehole Geophysics to Water Resources Investigations of the U.
S.' Geol. Survey:
Book 2, Chapter E-1, 126 pp.
Pirson, S.
J., 1963, Handbook of Well Log Analysis:
Englewood Cliffs, N.
J.,
Prentice Hall, Inc.
Schlumberger, 1972, Log Interpretation, Volume I-Principles, Schlumberger Limited.
Schlumberger, 1977.
Log Interpretation Charts, Schlumberger Limited.
i A-7 k
APPENDIX B DETERMINATION OF HYDRAULIC PROPERTIES 1.
INTRODUCTION Hydraulic gradient, hydraulic conductivity (saturated and unsaturated),
transmissivity, permeability, storage, and leakance are some of the hydraulic properties that influence the rate of movement of contaminants in subsurface environments, and should be evaluated for adequate site characterization.
Hydraulic gradient is determined in the field by measuring hydraulic heads in piezometers and can be extrapolated over large areas from a network of monitor wells.
Saturated and unsaturated hydraulic conductivities, and other hydraulic properties are determined by a variety of field and/or laboratory methods.
2.0 HYDRAULIC GRADIENT Hydraulic gradient is the rate of change of hydraulic potential over the distance between the two points at which the potentials are measured.
The validity of data used to determine hydraulic gradients depends on the correct horizontal and vertical placement of piezometers and well screens.
Applicants are referred to the the papers by Brown, R.H.,
Konoplyantsev, A.A., Ineson, J. and Kovalevsky, V.S., 1975, Ground Water Studies, An International Guide for Research and Practice, and
- Patton, F.D., 1979, Ground Water Instrumentation for Mining Projects, for detailed information on proper piezometer construction, placement, and monitoring.
3.0 SATURATED HYDRAULIC CONDUCTIVITY Saturated hydraulic conductivity is a measure of ability of a porous medium to transmit fluid under a potential gradient.
It can be determined by field or laboratory methods.
There are advantages and disadvantages in almost all methods.
In selecting methods many factors must be considered including purpose of the test, reliability of the method, cost of the test and apparatus, time required to conduct the test, skill required to perform the test, geological setting and aquifer location, desired results, and data application.
The following is a list of some selected methods for obtaining saturated hydraulic conductivity:
i Laboratory Methods Direct methods 1.
Constant Head Permeameter i
2.
Falling Head Permeameter
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Indirect Methods 1.
Hazen Formula 2.
Kozeney - Carmen Equation 3.
Other empirical - theoretical equations (Todd, p. 54, 1959)
Field Methods Discharging and Recovery Well Methods 1.
Thiem Equalibruim Method 2.
Theis Method 3.
Hantush - Jacob and Hantush Modified Leaky Aquifer Methods 4.
Neumann - Witherspoon Leaky Aquifer Method Injection Tests 1.
Packer Tests 2.
Slug Tests 3.1 Laboratory Methods Standard direct methods for determining saturated hydraulic conductivity with laboratory permeameters are presented in U.S. Department of the Interior, Bureau of Reclamation, 1974, Earth Manual, laboratory tests E-13 and E-14.
Todd (1959), Wenzel (1942) and Cedergren (1977) also outline procedures for measuring the hydraulic conductivity of materials with laboratory permeameters.
Indirect methods for determining saturated hydraulic conductivity attempt to quantify by mechanical analyses the many physical properties of a granular material, such as grain size and distribut'an, shape, porosity, and relate them to hydraulic conductivity.
The granular material is analyzed for parameters which influence its intrinsic permeability.
Cedergren (1977) states that saturated hydraulic conductivity determined from an indirect method should be viewed as an approximation, and Wenzel (1942) wrote that the direct determination of saturated hydraulic conductivity is generally preferable to indirect methods.
Indirect methods should be used only when geological conditions are well known and laboratory samples accurately represent field conditions.
Indirect methods may be used when other methods are too costly or too difficult to perform under existing conditions, and should always be tested against other types of measurements.
Problems with indirect methods include:
- 1) choosing a formula and specifying values of constants to obtain reliable results, 2) disturbed samples may no longer represent field conditions, 3) difficulty of including all possible variables of the granular material in the l
equation, and 4) careful mechanical analysis of the material is required.
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3.2 Field Methods 3.2.1 Discharging and Recovery Well Methods Discharging and recovery well methods have advantages over other permeability tests because they facilitate testing of relatively large areas and thicknesses of saturated porous media under in situ field conditions.
Therefore, the saturated hydraulic conductivity obtained should more closely represent that true field value of the hydrostratigraphic unit being tested.
Several discharging and recovery well methods are available for determining saturated hydraulic conductivity.
They are based on the Thiem (1906) steady-state or equalibrium method, and the Theis (1935) nonequalibrium method for non-leaky aquifers.
For leaky artesion aquifers the Hantush-Jacob (1955), Modified Hantush (1960), and Neuman-Witherspoon (1969 a, b, and 1972) methods should be employed.
Modifications to all these methods are available and must be applied if water table conditions, partial aquifer penetration, boundary conditions, declining pumping rates, barometric pressure changes, tidal effects, or multiple confined aquifers are encountered.
Selection of one of these methods should be based on existing geologic and hydrologic conditions, length of the test, distribution of observation wells, and data application.
3.2.1.1 Theim Equilibrium Method The Theim (1906) equilibruim method is used to calculate hydraulic conductivity within homogeneous, isotropic, confined or unconfined aquifers of infinite areal extent with no leakage or recharge.
This method requires a pumping well which fully penetrates the aquifer and at least two nearby observation wells to monitor water level changes in the pumped zone.
The well is pumped at a constant rate until a steady-state condition is approximated.
This occurs at a time such that additional drawdown in a pair of observation wells is considered negligible; a somewhat subjective decision.
The Thiem equilibrium method is based upon the following assumptions:
1.
The aquifer is homogeneous, isotropic and infinite in areal extent.
2.
The pumped well and/or observation wells fully penetrate the aquifer.
3.
The hydraulic gradient is zero with depth, and the horizontal gradient is equal to the slope of the cone of depression at any point.
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4.
Flow is uniform and horizontal.
If the pumped well or observation wells only partially penetrate the agt'ifer, special considerations must be observed.
Corrections for partial penetration are outlined by Lohman (1972) and Walton (1962).
The Thiem equilibrium method may yield acceptable results when the above assumptions are met.
The major drawback to the method is the length of time needed to reach " steady-state" and cost of running a long duration test.
Under water table (unconfined) conditions, many days may be required to approach equilibrium conditions.
For this reason, nonequilibrium methods are considered more acceptable and are widely used.
3.2.1.2 Theis Non-equilibrium Method The Theis (1935) nonequilibrium method is used extensively to determine
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the hydraulic characteristics of aquifers.
Parameters determined include transmissivity (T), storage coefficient (S), and saturated hydraulic conductivity (K).
The equations derived by Theis apply to nonleaky artesian aquifers although they may also be applied to water table aquifers as long as a correction factor is applied to the measured drawdowns.
The Theis nonequilibrium method is based upon the following assumptions:
1.
The aquifer is homogeneous and isotropic.
2.
The aquifer has an infinite areal extent.
3.
The discharging well fully penetrates the aquifer.
4.
The well has an infinitesimal diameter.
5.
The water removed from storage is discharged instantaneously with decline in head.
6.
Transmissivity is constant.
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A constant discharge well and a minimum of one observation well are needed to conduct this test.
Drawdown in the pumped well should not be allowed to drop below the bottom of the confining layer overlying the artesian aquifer being tested.
Solutions to the Theis equation are obtained by graphical methods involving curve matching of field data to a type curve representing a solution to the equation.
The reader should refer to Wenzel (1942), Todd (1959), Davis and DeWeist (1966), Walton (1962), Domenico (1972), and Lohman (1972) for detailed discussions on several ways in which type curves and field data may be I
prepared.
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Under water table conditions, observed drawdowns in wells should be corrected before they are used in the Theis equation. This correction factor derived by Jacob (1944) is used to adjust drawdown data for a decrease in transmissivity due to dewatering the aquifer.
Finite boundaries, either recharge or barrier, create special problems in aquifer pump test data analysis.
If boundaries are present, one of the basic assumptions for the Theis method is not met.
If boundary conditions are present field drawdown data departures from the type curve should occur.
Boundary conditions require matching data to a special set of type curves.
These type curves are avalable in Lohman (1972).
The Theis nonequilibrium method gives valid results when the assumptions are approximated and a sufficient amount of drawdown data are available.
The value of hydraulic conductivity obtained represents the average over a large area under natural conditions.
Various authors describe a simplified straight line or " Jacob type" graphic solution to the Theis equation.
This method is an approximation method whose accuracy diminishes as distance between pumped well and observation well increases, or when the pumping time is too short.
Normally, this occurs when p>0.01.
The method should not be considered as an adequate substitute for more precise curve matching techniques, but only as a check on those methods.
3.2.1.3 Hantush - Jacob and Hantush Modified Leaky Artesian Methods The Hantush-Jacob (1955) equation is used to determine aquifer characteristics for nonsteady-state radial flow in leaky artesian aquifers as well as the calculation of saturated hydraulic conductivity (K) of a single leaky confining layer.
The leaky artesian formula is based on the following assumptions:
1.
The aquifer is homogeneous and isotropic.
2.
The aquifer has infinite areal extent.
3.
The aquifer is confined between an impermeable bed and a bed through which leakage can occur.
4.
The coefficient of storage is constant.
5.
Water is released from storage instantaneously with a decline in head.
6.
The well has an infinitesimal diameter and fully penetrates the aquifer.
7.
Leakage through the confining bed into the aquifer is vertical and flow in the aquifer is horizontal.
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k 8.
Water does not come from storage within the confining bed.
9.
The water body supplying leakage remains at a constant head.
Solutions to the leaky artesian formula are obtained by graphical methods similar to the one used in the Theis method.
Prepared type curves for the Hantush-Jacob Method are presented by Walton (1962) and Lohman (197:).
Because the adjustment of hydraulic gradient through a confining bed generally lags considerably behind the decline in head in the aquifer, water yielded by an artesian aquifer is derived largely, if not entirely from storage in the confining unit.
Therefore, most time drawdown plots deviate from the Theis curve to a greater degree than if leakage alone were involved (Lohman, 1972).
Hantush (1960) developed a modified theory for confined leaky aquifers taking into account the storage of water in semipervious confining beds.
Use of this method will yield lower values for aquifer transmissivity and storage than will methods applied under the often mistaken assumption that leakage alone is involved (Lohman, 1972).
However, the method does not appear to allow for the determination of hydraulic properties of individual confining units when a leaky aquifer is bounded by more than one semipervious confining layer.
3.2.1.4 Neuman - Witherspoon Method The Neuman-Witherspoon (1969a, 1969b, and 1972) method is used for analyzing aquifer pump test data in a confined leaky aquifer where water is released from storage in the aquitard as well as from water " leaking" from the unpumped aquifer.
The method requires that observation wells be placed not only in the aquifer being pumped but also in the confining layers (aquitards) above and/or balow.
The ratio of the drawdown in the aquitard to that measured in the aquifer at the same time and same radial distance from the pumped well is used to evaluate hydraulic properties of the aquitard.
Hydraulic properties of the confined aquifer can also be determined.
The features of the Neuman-Witherspoon (1972) method are as follows:
1 1.
The method applies to arbitrary, multiple leaky aquifer situations.
2.
The pumped aquifer can be either confined or unconfined.
3.
The confining layers can be heterogeneous and anisotropic.
The ratio method gives the average vertical permeability over the thickness z of the aquitard being tested.
4.
The method relies only on early drawdown data, and tharefore, the pumping test can be of relatively short duration.
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5.
The drawdown data in the unpumped aquifer or in the aquitard provide an in situ indication of the time limit at which the ratio method ceases to give reliable results.
6.
Because the method is more sensitive to time lag than to the actual magnitude of s'/s, (where s' is the drawdown in the aquitard and s is the drawdown in the aquifer) the accuracy with which drawdowns are measured in the aquitard is not overly critical.
7.
The method does not require prior knowledge of the aquitard thickness.
8.
The ratio method is simple to use and does not involve graphical curve-matching procedures.
This lack of curve-matching procedures is an advantage because curve matching is often prone to variations in individual judgement and because a more reliable result can be obtained by taking the arithmetic average of results from several values of the radio s'/s.
The Neuman-Witherspoon method for conducting leaky aquifer pumping tests is currently the method most applicable to the multiple leaky aquifer-aquitard systems associated with most uranium deposits.
The method yields values of hydraulic conductivity for individual confining units, which, from a regulatory standpoint, is the most important property of an aquifer system to assess, as the confining units contribute to immobilization or isolation of mining fluids and wastes.
Drawbacks to this method are the additional expense of constructing wells in the aquitard(s) and aquifer (s) surrounding the aquifer being pumped, and the specific storage of the aquitard(s) must be known.
- However, specific storage can be determined in the field using borehole of tensiometers, and in the laboratory using standard consolidation tests on cores.
In the absence of field or laboratory measurements, specific storage can be estimated by correlating with published values for similar sediments.
3.2.2 Injection Tests In situ hydraulic conductivity values can be determined by means of injection and recovery tests conducted in a single piezometer.
Such tests yield valuable information on the hydraulic properties of a hydrogeologic unit when conducted under well controlled conditions.
These tests are simpler and cheaper in comparisca to aquifer pumping tests and they can provide adequate data in many cases where pumping tests are not justified (Freeze and Cherry, 1979).
(NOTE:
The various types of injection tests discussed below are not generally applicable to solutim. mining sites. )
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l 3.2.2.1 Packer Tests Several arrangements of borehole injection tests are described by the U.S. Bureau of Reclamation (1974) (Designation E-18).
These tests involve pumping water-into the formation being tested through the open end of a cased borehole or a section of borehole isolated by packers (packer testing) and should be used to evalute relative rather than absolute permeabilities.
Although injection and packer tests can be very useful, there are several problems inherent in them.
Some of the most frequent causes of error in these tests are listed by Cedergren (1977).
1.
Leakage along casing and around packers.
2.
Clogging due to sloughing of fines or sediment in the test water.
3.
Air locking due to gas bubbles in soil or water.
(Probably the most serious limitation.)
4.
Flow of water into cracks in soft rocks that are opened by excessive head in test holes.
In addition, when injection or packer tests are performed in initially unsaturated materials, the flow systems from which saturated hydraulic conductivity is calculated are influenced by boundary conditions and the unsaturated conductivity at the boundaries of the wetting front.
These effects are impossible to evaluate and correct, and are likely to invalidate tests performed in unsaturated materials.
3.2.2.2 Slug Tests and Bail Tests Hvorslev (1951) and Cooper el al (1967) developed techniques for interpreting water level change versus time arising from bail tests (when water is removed) or slug tests (when water is injected).
Both tests are initiated by causing an instantaneous change in the water level in a piezometer through a sudden introduction of a known volume of water.
Slug tests and bailer tests are useful for obtaining estimates of the hydraulic properties of a medium in the immediate vic.inity of the piezometer tested.
Results from these tests should not stand alone, but should be compared to and used with results from more accurate tests (i.e., aquifer pumping tests).
The reader is referred to Freeze and Cherry (1979) for detailed descriptions of slug tests and bail t.ests.
3.3 Conclusions and Recommendations Regarding Measurements of Saturated Hydraulic Conductivity The selection of methods most applicable to any particular groundwater flow problem should be based on the desired accuracy of the results, and l
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the geology and hydrology of the area in question.
It is generally accepted that field techniques are preferable to laboratory methods because the determination of hydraulic conductivity is made in place.
Furthermore, permeability determined in the field is applicable to a wider area and represents an average for the formation accounting for variations in the arrangement of the water-bearing material (Wenzel, 1942).
However, if that average value of hydraulic conductivity is applied to calculating the rate of movement of a contaminant, the predicted velocity will be too low because the most rapid rate of preferential movement will be determined by the highest permeability layer within the hydrostratigraphic unit.
This problea can be eliminated by testing all layers of greatest permeability individually with peizometers.
Layers of relatively high or low permeability can be identified by well logs, packer tests, drill cores, and geophysical j
logging methods.
When discharging and recovery aquifer test methods are performed for site characterization, it is necessary that the tests be conducted for sufficient length to insure an adequate assessment of aquifer confinement.
If injection tests are to be utilized to measure saturated hydraulic conductivity, it is particularly important to make sure fluid is injected into a saturated zone or that a very large saturated zone is created by the test prior to measuring K.
Injection tests which inject water into an unsaturated zone do not have a sound theoretical base and may give erroneous results, because they measure the rate of movement of a wetting front outward from the point of injection.
The permeability of an unsaturated zone is a direct function of moisture content.
Consequently, the value of K calculated from such a test will always be less than the true value of K.
If the value of K obtained from such an injection test in unsaturated material is applied to the rate of movement of a contaminant, the predicted rate of movement of the contaminant will always be lower than the rate that will occur in the field.
The use of injection tests in unsaturated porous media is perhaps the most common source of miscalculation in the analysis of potential groundwater contamination near proposed uranium mill tailings disposal facilities.
Factors of primary importance in all measurements of saturated (and unsaturated) hydraulic conductivity are:
1.
Selection of a method compatible with hydrogeologic conditions.
2.
Recognition of the limitations and assumptions of the method used.
3.
Testing only the proper hydrostratigraphic unit as defined before the test.
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4.
'Have the test conducted and analyzed by someone thoroughly familiar with the test, geology, and the test's application to the hydrogeologic environment in question.
4.
UNSATURATED HYDRAULIC CONDUCTIVITY The following is a list of some selccted methods for obtaining unsaturated hydraulic conductivity:
I.
Laboratory Methods A.
Steady-State Methods 1.
Short Column 2.
Lonq Column B.
Unsteady-State Methods 1.
Outflow-Inflow Methods 2.
Instantaneous Profile Methods 3.
Unit Gradient - Drainage Method C.
From Water Retardation Data II Field Methods A.
Double Tube Method B.
Injection Tests The method selected for determining unsaturated hydraulic conductivity depends on whether precise measurements on a relatively small number of samples are needed or extensive characterization of the medium in the field is needed.
For more details on each method, including a description of apparatus required, reliability of the method, its limitations and assumptions, and geologic conditions best suited to the test method, and a list of additional references on the subject of unsaturated hydraulic conducivity, the reader is referred to Klute, A.,
1972, The Determination of the Hydraulic Conductivity and Diffusivity of Unsaturated Soils:
Soil Science, Vol. 113, Number 4, pp. 264-276.
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REFERENCES (APPENDIX B)
Brown, R.
H., Konoplyantsev, A.
A., Ineson, J. and Kovalevsky,-V. S.,
1975, Ground Water Studies, An International Guide for Research and Practice:
The Unesco Press, Paris, France.
1 Cedergren, H. R., 1977, Chapter 2 on Permeability in Seepage, Drainage, and Flow Nets, 2nd ed., John Wiley & Sons, pp. 26-85.
Cooper, H. H., Jr., J. D. Bredehoeft, and I. S. Papadopoulos, 1967.
Response to a finite-diameter well to an instantaneous charge of water, Water Resources Res., 3, pp. 263-269.
Davis, S.
N., and Dewiest, R. J. M., 1966, Hydrogeology:
John Wiley &
Sons, Inc., 463 pp.
Domenico, P.
A., 1972, Concepts and Models in Groundwater Hydrology:
McGraw-Hill Book Co., 405 pp.
Freeze, R. A., and Cherry, J. A.,1979, Groundwater:
Practice-Hall, Inc., Englewood Cliffs, N.J., 604 pp.
Hantush, M.
S., and Jacob, C.
E., 1955, Nonsteady Radial Flow in an Infinite Leaky Aquifer:
Trans. Amer. Geophys. Union, vol. 36, pp.95-100.
Hantush, M.
S., 1960, Modification of the Theory of Leaky Aquifers:
J. Geophys. Res., vol. 65, pp. 3713-3725
- Hazen, A., 1893, Some Physical Properties of Sands and Gravels with Special Referance to Their Use in Filtration:
245h Ann. Rep., Mass State Bd. Health, Boston, pp. 542-556 Hvorslev, M.
J., 1951, Time lag and soil permeability in groundwater observations.
U.S. Army Corps Enges. Waterways Exp. Sta. Bull. 36, Vicksburg, Miss.
Jacob, C. E., 1944, Notes on Determining Permeability by Pumping Tests Under Water-Table Conditions:
U.S. Geol. Survey mimeo Rept.
- Klute, A., 1972, The Determination of the Hydraulic Conductivity and Diffusivity of unsaturated Soils:
Soil Science, Vol. 113, Number 4, pp. 264-276.
- Kozeney, J., 1927, Uber Kapillare Leitung des Wassers in Boden, Sitzber, Wiener Akad. Wiss., vol. 136, pt. 2.
Lohman, S. W., 1972, Ground Water Hydraulics:
U.S. Geol. Survey, Professional paper 708, 70 pp.
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l l
Neuman, S. P. and P. A. Witherspoon, 1969a. Theory of flow in a confined l
two aquifer system. Water Resources Research, V. S. No. 5, pp. 803-816.
l Neuman, S. P. and P. A. Witherspoon, 1969b.
Applicability of Current Theories of Flow in Leaky Aquifers.
Water Resources Research. V. 5, No. 5, pp. 817-829.
Neuman, S. P. and P. A. Witherspoon, 1972.
Field Determination of the Hydraulic Properties of Leaky Multiple Aquifer Systems. Water Resources Research.
V. 8, No. 5, pp. 1284-1298.
Patton, F. D., 1979, Ground Water Instrumentation for Mining Projects:
Proceedings, 1st International Mine Drainage Symposium, Miller Freeman Publ. Co., 500 Howard St., San Francisco, California.
Todd, D.
K., 1959, Ground Water Hydrology; John Wiley and Sons, Inc.,
New York, 336 pp.
Thiem, G., 1906 Hydrologische Methoden, Leipzig, J. M. Gebhart, 56 pp.
Theis, C.
F., 1935, The Relation Between the Lowering of the Piezometric Surface and the Rate and Duration of Discharge of a Well Using Grouad Water Storage:
Am. Geophys. Union Trans., vol. 16, pp. 519-524.
U.S. Dept. of the Interior, Bureau of Reclamation, 1974, Earth manual:
Washington, D.C., 810 pp.
Walton, W.
C., 1962, Selected Analytical Methods for Well and Aquifer Evaluation:
Ill. State Water Survey Bull. 49, 81 pp.
Wenzel, L. K.,1942, Methods for Determining Permeability of Water-Bearing Materials with Special Reference to Discharging Well Methods:
U.S. Geol. Survey Water Supply Paper 887, 192 pp.
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