The preparation of field logs provides documentation of field exploration procedures and findings for geotechnical, geologic, hydrogeologic, and other investigations of subsurface site conditions. This guide may be used for a broad range of investigations.The recorded information in a field log will depend on the specific purpose of the site investigation. All of the information given in this guide need not appear in all field logs.Note 1—The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective sampling. Users of this practice are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.1.1 This guide describes the type of information that should be recorded during field subsurface explorations in soil and rock.1.2 This guide is not intended to specify all of the information required for preparing field logs. Such requirements will vary depending on the purpose of the investigation, the intended use of the field log, and particular needs of the client or user.1.3 This guide is applicable to boreholes, auger holes, excavated pits, or other subsurface exposures such as road side cuts or stream banks. This guide may serve as a supplement to Guide D420.1.4 This guide may not be suited to all types of subsurface exploration such as mining, agricultural, geologic hazardous waste, or other special types of exploration.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.1.6 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care of which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.

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Concepts:This guide summarizes the equipment, field procedures, and interpretation methods for using the metal detection method for locating subsurface metallic objects. Personnel requirements are as discussed in Practice D3740.Method—Metal detectors are electromagnetic instruments that work on the principle of induction, using typically two coils (antennas); a transmitter and a receiver. Both coils are fixed in respect to each other and are used near the surface of the earth. Either an alternating or a pulsed voltage is applied to the transmitter coil causing electrical eddy currents to be induced in the earth. The electrical currents flowing in the earth are proportional to electrical conductivity of the medium. Theses currents generate eddy currents in buried metallic objects that is detected and measured by the receiver (Fig. 1).Parameter Measured and Representative Values:Frequency Domain Metal Detectors:Frequency domain metal detectors apply an alternating current having a fixed frequency and amplitude to the transmit coil which generates a time-varying magnetic field around the coil. This field induces eddy currents in nearby metallic objects that in turn generate time-varying magnetic fields of their own. These eddy-fields induce a voltage in the receiver coil. The presence of metal causes small changes in the phase and amplitude of the receiver voltage. Most metal detectors amplify the differences in the receiver coil voltage caused by nearby metal and generate an audible sound or meter (analog or digital) reading.Ground conductivity meters (frequency domain metal detectors) measure the two-components of the secondary magnetic field simultaneously. The first is the quadrature-phase component which indicates soil electrical conductivity and is measured in millisiemens per meter (mS/m). The second is the inphase component, which is related to the subsurface magnetic susceptibility and is measured in parts per thousand (ppt) (that is, the ratio between the primary and secondary magnetic fields).(1) Conductivity Measurements (Quadrature-Phase Component)Metallic objects within a few feet of the surface will cause induced magnetic field distortions that will result in zero or even negative values of measured conductivity. Deeper metallic objects will cause less field distortion and lead to measured conductivities which are abnormally high in comparison to site background values.(2) Inphase ComponentInphase measurements are more sensitive to metal than conductivity measurements. Thus, inphase anomalies may indicate the presence of metal at a greater depth than the conductivity measurements.Time Domain Metal Detectors:In time domain metal detectors, a transmitter generates a pulsed primary magnetic field in the earth. After each pulse, secondary magnetic fields are induced briefly from moderately conductive earth, and for a longer time from metallic targets. Between each pulse, the metal detector waits until the response from the conductive earth dissipates, and then measures the prolonged buried metal response. This response is measured in millivolts (mV).Equipment—Metal detectors generally consist of transmitter electronics and transmitter coil, power supply, receiver electronics and receiver coil. Metal detectors are usually single individual portable.Typical “treasure-hunter” metal detectors provide an audible signal and/or meter reading (analog or digital) when metal is detected.Quadrature and inphase measurements from ground conductivity meters are shown either on analog or digital meters. These measurements can often be recorded digitally in the field using a small field recorder, strip-chart recorder, or computer.Time domain metal detectors can consist of either one or two receiver coils. When two coils are used, one coil is typically placed above the other. Readings from both coils are recorded simultaneously. In order to improve detection of deeper metallic targets, the differential response from the two receiver coils can be used to suppress the response from smaller, shallower metallic targets. Some time domain metal detectors are mounted on wheels, allowing for the use of odometers to provide location data.Limitations and Interferences:General Limitations Inherent to Geophysical Methods:A fundamental limitation of all geophysical methods is that a given set of data cannot be associated with a unique set of subsurface conditions. In most situations, surface geophysical measurements alone cannot resolve all ambiguities, and some additional information, such as borehole data, is advised. Because of this inherent limitation in the geophysical methods, a metal detector survey alone can never be considered a complete assessment of subsurface conditions. Properly integrated with other geologic information, metal detector surveying is a highly effective method of obtaining subsurface information.In addition, all surface geophysical methods are inherently limited by decreasing resolution with depth.Limitations Specific to the Metal Detection Method:Several factors influence metal detector response: the properties of the target, the properties of the soil/rock, and the characteristics of the metal detector itself. The target’s size, depth, and condition of burial are the three most important factors.The larger the surface area of the target, the greater the eddy current that may be induced, and the greater the depth at which the target may be detected.The metal detector’s response decreases at a rate equal to the reciprocal of its depth up to the sixth power (1/depth6). Therefore, if the distance to the target is doubled, the metal detector response will decrease by a factor of 64. Consequently, the metal detector is a relatively shallow-depth device. It is generally restricted to detecting small objects at relatively shallow depths or larger targets at limited depths. Generally, most metal detectors are incapable of responding to targets at depths much greater than 6 m.Although the shape, orientation, and composition of a target will influence the metal detector response, these factors will have much less influence than will the size and depth of the target. Target deterioration, however, has a significant impact. Metallic containers will corrode in natural soils conditions. If a container is corroded, its surface area will be significantly reduced, and in turn will degrade the response of a metal detector.Because the metal detector’s response weakens rapidly with increasing distance to the target, system gain and instrument stability are important. The size of the coil controls the size and depth of the metallic target that can be detected as shown in Fig. 2.Interferences Caused by Natural and Cultural Conditions:Sources of noise referred here do not include those of a physical nature such as difficult terrain or man-made obstructions but rather those of a geologic, ambient, or cultural nature that can adversely affect the measurements and hence the interpretation.Natural Sources of Noise—Some kinds of soil/rock, particularly those containing high iron content (often known as mineralized soil) affect receiver coil output strongly enough to indicate the presence of a metal target with certain kinds of metal detectors. Some types of metal detectors provide a means for compensating the output for the ground effect. This usually requires the operator to position the detector near the ground (but not near a metal target) and adjust a control until the target signal disappears. Small variations in the soil characteristics and stones (particularly those containing metallic compounds) can cause small changes in the detector output. Often these changes cause small target-like signals, known as “ground noise.” These can confuse the operator because they sound like small targets.Cultural Sources of Noise—Cultural sources of noise can include interference from electrical power lines, communications equipment, nearby buildings, and metal fences. Interference from power lines is inversely proportional to the distance between power line and detector; therefore most metal detectors with small coils are generally unaffected.Surveys should not be made in close proximity to buildings, metal fences or buried metal pipe lines that can be detected by the metal detection method, unless detection of the buried pipe line, for example, is the object of the survey. It is sometimes difficult to predict the appropriate distance from the potential sources of noise. Measurements made on-site can quickly yield the magnitude of the problem, and adjustments can then be made.Precaution must also be taken to remove metal from the operator, or to minimize its effects. Steel-toe boots, respirators, and air bottles can all cause considerable problems with noise.Summary—During the course of designing and carrying out a metal detection survey, the sources of ambient, geologic and cultural noise must be considered and the time of occurrence and location noted. The exact form of the interference is not always predictable, as it not only depends upon the type of noise and the magnitude of the noise but also upon the distance from the source of noise and possibly the time of day.1.1 Purpose and Application—This guide summarizes the equipment, field procedures, and interpretation methods for the assessment of subsurface materials using the metal detection method. Metal detectors respond to the presence of both ferrous and nonferrous metals by inducing eddy currents in conductive objects. Metal detectors are either frequency domain (continuous frequency or wave) or time domain (pulsed) systems. A wide range of metal detectors is commonly available.1.1.1 Metal detectors can detect any kind of metallic material, including both ferrous metals such as iron and steel, and non-ferrous metals such as aluminum and copper. In contrast, magnetometers only detect ferrous metals.1.1.2 Metal detector measurements can be used to detect the presence of buried metal trash, drums (Tyagi et al, 1983) (1) and tanks, abandoned wells (Guide D6285); to trace buried utilities; and to delineate the boundaries of landfill metal and trench metal. They are also used to detect metal based unexploded ordnance (UXO).1.2 Limitations:1.2.1 This guide provides an overview of the metal detection method. This guide does not provide or address the details of the theory, field procedures, or interpretation of the data. References are included for that purpose and are considered an essential part of this guide. It is recommended that the user of this guide be familiar with the references cited and with the ASTM standards D420, D653, D5088, D5608, D5730, D5753, D6235, D6429, and D6431.1.2.2 This guide is limited to metal detection measurements made on land. The metal detection method can be adapted for a number of special uses on land, water, airborne and ice.1.2.3 The approaches suggested in this guide for the metal detection method are commonly used, widely accepted, and proven. However, other approaches or modifications to the metal detection method that are technically sound may be substituted.1.2.4 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.3 The values stated in SI units are regarded as standard. The values given in parentheses are inch-pound units, which are provided for information only and are not considered standard.1.4 Precautions:1.4.1 It is the responsibility of the user of this guide to follow any precautions in the equipment manufacturer's recommendations and to establish appropriate health and safety practices.1.4.2 If the method is used at sites with hazardous materials, operations, or equipment, it is the responsibility of the user of this guide to establish appropriate safety and health practices and to determine the applicability of any regulations prior to use.1.4.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.

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5.1 The use of vapor extraction systems (VES), also called soil vapor extraction (SVE) or venting systems, is becoming a common remedial technology applicable to sites contaminated with volatile compounds (3, 4). A vapor extraction system is composed of wells or trenches screened within the vadose zone. Air is extracted from these wells to remove organic compounds that readily partition between solid or liquid phases into the gas phase. The volatile contaminants are removed in the gas phase and treated or discharged to the atmosphere. In many cases, the vapor extraction system also incorporates wells open to the atmosphere that act as air injection wells.Note 1—Few model codes are available that allow simulation of the movement of air, water, and nonaqueous liquids through the subsurface. Those model codes that are available (5, 6), require inordinate compute hardware, are complicated to use, and require collection of field data that may be difficult or expensive to obtain. In the future, as computer capabilities expand, this may not be a significant problem. Today, however, these complex models are not applied routinely to the design of vapor extraction systems.5.2 This guide presents approximate methods to efficiently simulate the movement of air through the vadose zone. These methods neglect the presence of water and other liquids in the vadose zone; however, these techniques are much easier to apply and require significantly less computer hardware than more robust numerical models.5.3 This guide should be used by groundwater modelers to approximately simulate the movement of air in the vadose zone.5.4 Use of this guide to simulate subsurface air movement does not guarantee that the airflow model is valid. This guide simply describes mathematical techniques for simulating subsurface air movement with groundwater modeling codes. As with any modeling study, the modeler must have a thorough understanding of site conditions with supporting data in order to properly apply the techniques presented in this guide.1.1 This guide covers the use of a groundwater flow modeling code to simulate the movement of air in the subsurface. This approximation is possible because the form of the groundwater flow equations are similar in form to airflow equations. Approximate methods are presented that allow the variables in the airflow equations to be replaced with equivalent terms in the groundwater flow equations. The model output is then transformed back to airflow terms.1.2 This guide illustrates the major steps to take in developing an airflow model using an existing groundwater flow modeling code. This guide does not recommend the use of a particular model code. Most groundwater flow modeling codes can be utilized, because the techniques described in this guide require modification to model input and not to the code.1.3 This guide is not intended to be all inclusive. Other similar techniques may be applicable to airflow modeling, as well as more complex variably saturated groundwater flow modeling codes. This guide does not preclude the use of other techniques, but presents techniques that can be easily applied using existing groundwater flow modeling codes.1.4 This guide is one of a series of standards on groundwater model applications, including Guides D5447 and D5490. This guide should be used in conjunction with Guide D5447. Other standards have been prepared on environmental modeling, such as Practice E978.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.1.7 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.

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4.1 The 1998 edition of this standard was written solely for selection of drilling methods for environmental applications and specifically for installation of groundwater monitoring wells. The second revision was made to include geotechnical applications since many of the advantages, disadvantages, and limitations discussed extensively throughout this document also apply to geotechnical design use such as data collection (sampling and in-situ testing) for construction design and instrumentation. Besides installation of monitoring wells (D5092/D5092M, D6724/D6724M), Environmental investigations are also made for sampling, in-situ testing, and installation of aquifer testing boreholes (D4044/D4044M, D4050).4.2 There are other guides for geotechnical investigations addressing drilling methods such as in Eurocode (1, 2)5, U.S. Federal Highway Administration, (3, 4), U.S. Army Corps of Engineers, (5), and U.S. Bureau of Reclamation (6, 7). An authoritative Handbook on Environmental Site Characterization and Ground-Water Monitoring was compiled by Nielsen (8) which addresses drilling methods in detail including the advent of Direct Push methods developed for environmental investigations. Two other major drilling guides have been written by the National Drilling Association (9) and from the Australia Drilling Industry Training Committee (10) and these guides are user for the drillers.4.3 Table 1 lists sixteen classes of methods addressed in this guide. The selection of particular method(s) for drilling/push boring requires that specific characteristics of each site be considered. This guide is intended to make the user aware of some of the various drilling/push boring methods available and the applications, advantages, and disadvantages of each with respect to determining geotechnical and environmental exploration.(A) Actual achievable drilled depths will vary depending on the ambient geohydrologic conditions existing at the site and size of drilling/push boring equipment used. For example, large, high-torque rigs can drill to greater depths than their smaller counterparts under favorable site conditions. Boreholes drilled using air/air foam can reach greater depths more efficiently using two-stage positive-displacement compressors having the capability of developing working pressures of 12 to 17 kPa [250 to 350 psi] and 14 to 21 m3/h [500 to 750 cfm], particularly when submergence requires higher pressures. The smaller rotary-type compressors only are capable of producing a maximum working pressure of 6 kPa [125 psi] and produce 14 to 34 m3/h [500 to 1200 cfm]. Likewise, the rig mast must be constructed to safely carry the anticipated working loads expected. To allow for contingencies, it is recommended that the rated capacity of the mast be at least twice the anticipated weight load or normal pulling load.(B) Soil = S (Cuttings), Rock = R (Cuttings), Fluid = F (some samples might require accessory sampling devices to obtain).(C) I = Incremental sampling, C = continuous sampling.4.3.1 On Table 1, practically all methods allow for coring, but some are much more efficient than others. Some drilling systems such as hollow-stem augers or wireline coring allow for practically continuous coring with minimal time for switching barrels while other drilling methods require the whole drilling equipment be removed from the hole. A prime example is the rate of rock coring using fluid rotary and conventional core barrels versus wireline rock coring. Wireline line rock coring is fast with long continuous runs whereas fluid rotary requires more “trip time” to add and remove shorter length core barrels using drill rods. Table 1 delineates methods where coring is possible, and in general, by either continuous (c) or incremental (i) sampling.4.3.2 Sampling for environmental contaminants in soil, unconsolidated formations or groundwater often requires special considerations. In many environmental applications the use of drilling fluids (air, water, mud or foam) is often discouraged or even prohibited as these fluids may dilute the analytes of interest or even introduce analytes of concern not previously present (see 5.4).4.4 This guide is most often used in conjunction with Guide D6169/D6169M on soil and rock sampling because sampling is the primary activity during drilling/push borings. There are several guides that deal with individual drilling methods (see Guides D5781/D5781M, D5782, D5783, D5784, D5872, D5875/D5875M, and D5876/D5876M) and how to the complete them for water quality monitoring well installations (see Practice D5092/D5092M). Practices on hollow-stem auger (D6151/D6151M) and sonic drilling (D6914/D6914M) were written for both geotechnical and environmental purposes and address sampling methods. Practice D2113 on rock core drilling includes sampling methods.4.4.1 This guide covers direct push methods that are only used to make open holes for testing and sampling. This most often accomplished using dual tube systems and using the tubes for access of the subsurface for water sampling, D6001, soil sampling (D6282/D6282M), well installation (D6724/D6724M, D6725/D6725M) and aquifer testing (D7242/D7242M).4.5 Predominant or Typical Drilling/Push Boring Methods Used for Geotechnical and Environmental Applications: 4.5.1 Geotechnical Investigations in Soils (unconsolidated deposits)—The most commonly used drilling methods for geotechnical exploration are fluid rotary drilling when groundwater is present. Hollow-stem auger drilling is also frequently used especially in arid regions where introduction of fluids is to be avoided in unsaturated soils.4.5.2 Environmental Investigations in soils (unconsolidated deposits)—Most of these investigations are focused on soil contamination or, groundwater quality investigations so introduction of drilling fluids is not desirable and methods which generate minimal waste are highly favored. Direct Push methods were developed because they develop minimal investigative derived waste (IDW). Sonic methods are frequently used and generate minimal IDW but large cores. Hollow-stem augers and fluid rotary are used yet they generate large amounts of IDW.4.5.2.1 At most environmental sites hazardous contaminants are present in the subsurface. Because of this fact any drill cuttings or drilling fluids returned to the surface should be properly handled, contained and stored (drums or roll-off bins, etc.) for sampling and laboratory analysis. Laboratory analyses may be required to verify that hazardous contaminants are not present above regulatory action levels prior to proper disposal. If concentrations of hazardous chemicals in cuttings or waste drilling fluids exceed regulatory action levels the waste may require treatment before disposal or may need to be properly disposed in a hazardous waste landfill. Review pertinent regulations before drilling/push boring to maintain compliance. The generation of contaminated waste drill cuttings and fluids significantly increase the potential for worker exposure to hazardous contaminants. Review pertinent regulations (such as OSHA 1910.120, etc.) to maintain compliance with worker safety and monitoring requirements.4.5.3 Rock, Weathered Rock, and Coarse Cobble Boulder Drilling—Wireline rock coring is used in competent rock and results in the best core recovery. For coarse grained unconsolidated deposits and weathered bedrock samples are very difficult to recover and, rotary air drill through drive casing advancers are often used and require larger drills. Larger sonic drills can also drill and recover rock and boulder formations.4.5.4 Sonic drilling methods have increased in use for both geotechnical and environmental explorations. The method offers very rapid continuous coring with the ability to drill difficult formations with large diameter equipment.4.5.5 Shallow hand auger (D4700) is used for both disciplines but in most cases hand applications are used as part of initial site surveys prior to drilling/push boring or just for characterization of shallow soil sampling. Hand auguring is very labor intensive and has almost been abandoned in favor of using direct push equipment.NOTE 1: The reliability of data and interpretations generated by this practice is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 generally are considered capable of competent testing. Users of this practice are cautioned that compliance with Practice D3740 does not assure reliable testing. Reliable testing depends on several factors and Practice D3740 provides a means of evaluating some of these factors.Practice D3740 was developed for agencies engaged in the testing, inspection, or both, of soils and rock. As such, it is not totally applicable to agencies performing these field practices. Users of this test method should recognize that the framework of Practice D3740 is appropriate for evaluating the quality of an agency performing drilling. Currently, there is no known qualifying national authority that inspects agencies that perform this test method. There is training and certification for drillers that are normally required for critical installations such as water well drilling (NGWA, NDA).1.1 This guide provides descriptions of various methods for site characterization along with advantages and disadvantages associated with each method discussed. This guide is intended to aid in the selection of drilling method(s) for geotechnical and environmental soil and rock borings for sampling, testing, and installation of wells, or other instrumentation. It does not address drilling for foundation improvement, drinking water wells, or special horizontal drilling techniques for utilities.1.2 This guide cannot address all possible subsurface conditions that may occur such as, geologic, topographic, climatic, or anthropogenic. Site evaluation for engineering, design, and construction purposes is addressed in Guide D420. Soil and rock sampling in drill holes is addressed in Guide D6169/D6169M. Pertinent guides and practices addressing specific drilling methods, equipment, and procedures are listed in Section 2. Guide D5730 provides information on most all aspects of environmental site characterization.1.3 The values stated in either SI units or inch-pound units (given in brackets) are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.1.4 This guide does not purport to comprehensively address all methods and the issues associated with drilling for geotechnical and environmental purposes. Users should seek qualified professionals for decisions as to the proper equipment and methods that would be most successful for their site investigation. Other methods may be available for these methods and qualified professionals should have flexibility to exercise judgment as to possible alternatives not covered in this guide. The guide is current at the time of issue, but new alternative methods may become available prior to revisions. Therefore, users should consult with manufacturers or producers prior to specifying program requirements.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5.1 Drilling operators generally are required to be trained for safety requirements such as those of construction and environmental occupational safety programs dictated by country, regional, or local requirements such as the US. OSHA training programs. Drilling safety programs are also available from the National Drilling Association (NDA4U.com) or other country drilling associations.21.6 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education and experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 Concepts:  5.1.1 This guide summarizes the equipment, field procedures, and interpretation methods used for the determination of the depth, thickness and the seismic velocity of subsurface soil and rock or engineered materials, using the seismic refraction method. 5.1.2 Measurement of subsurface conditions by the seismic refraction method requires a seismic energy source, trigger cable (or radio link), geophones, geophone cable, and a seismograph (see Fig. 1). FIG. 1 Field Layout of a Twelve-Channel Seismograph Showing the Path of Direct and Refracted Seismic Waves in a Two-Layer Soil/Rock System (αc = Critical Angle) 5.1.3 The geophone(s) and the seismic source must be placed in firm contact with the soil or rock. The geophones are usually located in a line, sometimes referred to as a geophone spread. The seismic source may be a sledge hammer, a mechanical device that strikes the ground, or some other type of impulse source. Explosives are used for deeper refractors or special conditions that require greater energy. Geophones convert the ground vibrations into an electrical signal. This electrical signal is recorded and processed by the seismograph. The travel time of the seismic wave (from the source to the geophone) is determined from the seismic wave form. Fig. 2 shows a seismograph record using a single geophone. Fig. 3 shows a seismograph record using twelve geophones. FIG. 2 A Typical Seismic Waveform from a Single Geophone Note 1: Arrow marks arrival of first compressional wave. FIG. 3 Twelve-Channel Analog Seismograph Record Showing Good First Breaks Produced by an Explosive Sound Source (2) 5.1.4 The seismic energy source generates elastic waves that travel through the soil or rock from the source. When the seismic wave reaches the interface between two materials of different seismic velocities, the waves are refracted according to Snell's Law (3, 4). When the angle of incidence equals the critical angle at the interface, the refracted wave moves along the interface between two materials, transmitting energy back to the surface (Fig. 1). This interface is referred to as a refractor. 5.1.5 A number of elastic waves are produced by a seismic energy source. Because the compressional P -wave has the highest seismic velocity, it is the first wave to arrive at each geophone (see Fig. 2 and Fig. 3). 5.1.6 The P-wave velocity Vp is dependent upon the bulk modulus, the shear modulus and the density in the following manner (3): where: Vp   =   compressional wave velocity, K   =   bulk modulus, μ   =   shear modulus, and ρ   =   density. 5.1.7 The arrival of energy from the seismic source at each geophone is recorded by the seismograph (Fig. 3). The travel time (the time it takes for the seismic P-wave to travel from the seismic energy source to the geophone(s)) is determined from each waveform. The unit of time is usually milliseconds (1 ms = 0.001 s). 5.1.8 The travel times are plotted against the distance between the source and the geophone to make a time distance plot. Fig. 4 shows the source and geophone layout and the resulting idealized time distance plot for a horizontal two-layered earth. FIG. 4 (a) Seismic Raypaths and (b) Time-Distance Plot for a Two-Layer Earth With Parallel Boundaries (2) 5.1.9 The travel time of the seismic wave between the seismic energy source and a geophone(s) is a function of the distance between them, the depth of the refractor and the seismic velocities of the materials through which the wave passes. 5.1.10 The depth of a refractor is calculated using the source to geophone geometry (spacing and elevation), determining the apparent seismic velocities (which are the reciprocals of the slopes of the plotted lines in the time distance plot), and the intercept time or crossover distances on the time distance plot (see Fig. 4). Intercept time and crossover distance-depth formulas have been derived in the literature (5-4). These derivations are straightforward inasmuch as the travel time of the seismic wave is measured, the velocity in each layer is calculated from the time-distance plot, and the raypath geometry is known. These interpretation formulas are based on the following assumptions: (1) the boundaries between layers are planes that are either horizontal or dipping at a constant angle, (2) there is no land-surface relief, (3) each layer is homogeneous and isotropic, (4) the seismic velocity of the layers increases with depth, and (5) intermediate layers must be of sufficient velocity contrast, thickness and lateral extent to be detected. Reference (2) provides an excellent summary of these equations for two and three layer cases. The formulas for a two-layered case (see Fig. 4) are given below. 5.1.10.1 Intercept-time formula: where: z   =   depth of refractor two, ti   =   intercept time, V2   =   seismic velocity in layer two, and V1   =   seismic velocity in layer one. 5.1.10.2 Crossover distance formula: where: z, V2 and V1 are as defined above and xc = crossover distance. 5.1.10.3 Three to four layers are usually the most that can be resolved by seismic refraction measurements. Fig. 5 shows the source and geophone layout and the resulting time distance plot for an idealized three-layer case. FIG. 5 (a) Seismic Raypaths and (b) Time-Distance Plot for a Three-Layer Model With Parallel Boundaries (2) Note 1: While these equations are suitable for hand calculations, more advanced algorithms are used in commercially available software that is generally used to analyze seismic traces. 5.1.11 The refraction method is used to define the depth to or profile of the top of one or more refractors, or both, for example, depth of water table or bedrock. 5.1.12 The source of energy is usually located at or near each end of the geophone spread; a refraction measurement is made in each direction. These are referred to as forward and reverse measurements, sometimes incorrectly called reciprocal measurements, from which separate time distance plots are made. Fig. 6 shows the source and geophone layout and the resulting time distance plot for a dipping refractor. The velocity obtained for the refractor from either of these two measurements alone is the apparent velocity of the refractor. Both measurements are necessary to resolve the true seismic velocity and the dip of layers (2) unless other data are available that indicate a horizontal layered earth. These two apparent velocity measurements and the intercept time or crossover distance are used to calculate the true velocity, depth and dip of the refractor. Note that only two depths of the planar refractor are obtained using this approach (see Fig. 7). Depth of the refractor is obtained under each geophone by using a more sophisticated data collection and interpretation approach. FIG. 6 (a) Seismic Raypaths and (b) Time-Distance Plot for a Two-Layer Model With A Dipping Boundary (2) FIG. 7 Time Distance Plot (a) and Interpreted Seismic Section (b ) (7) 5.1.13 Most refraction surveys for geologic, engineering, hydrologic and environmental applications are carried out to determine depths of refractors that are less than 100 m (about 300 ft). However, with sufficient energy, refraction measurements can be made to depths of 300 m (1000 ft) and more (5). 5.2 Parameter Measured and Representative Values:  5.2.1 The seismic refraction method provides the velocity of compressional P-waves in subsurface materials. Although the P-wave velocity is a good indicator of the type of soil or rock, it is not a unique indicator. Table 1 shows that each type of sediment or rock has a wide range of seismic velocities, and many of these ranges overlap. While the seismic refraction technique measures the seismic velocity of seismic waves in earth materials, it is the interpreter who, based on knowledge of the local conditions and other data, must interpret the seismic refraction data and arrive at a geologically feasible solution. 5.2.2 P-wave velocities are generally greater for: 5.2.2.1 Denser rocks than lighter rocks; 5.2.2.2 Older rocks than younger rocks; 5.2.2.3 Igneous rocks than sedimentary rocks; 5.2.2.4 Solid rocks than rocks with cracks or fractures; 5.2.2.5 Unweathered rocks than weathered rocks; 5.2.2.6 Consolidated sediments than unconsolidated sediments; 5.2.2.7 Water-saturated unconsolidated sediments than dry unconsolidated sediments; and 5.2.2.8 Wet soils than dry soils. 5.3 Equipment—Geophysical equipment used for surface seismic refraction measurement includes a seismograph, geophones, geophone cable, an energy source and a trigger cable or radio link. A wide variety of seismic geophysical equipment is available and the choice of equipment for a seismic refraction survey should be made in order to meet the objectives of the survey. 5.3.1 Seismographs—A wide variety of seismographs are available from different manufacturers. They range from relatively simple, single-channel units to very sophisticated multichannel units. Most engineering seismographs sample, record and display the seismic wave digitally. 5.3.1.1 Single Channel Seismograph—A single channel seismograph is the simplest seismic refraction instrument and is normally used with a single geophone. The geophone is usually placed at a fixed location and the ground is struck with the hammer at increasing distances from the geophone. First seismic wave arrival times (Fig. 2 and Fig. 3) are identified on the instrument display of the seismic waveform. For some simple geologic conditions and small projects a single-channel unit is satisfactory. Single channel systems are also used to measure the seismic velocity of rock samples or engineered materials. 5.3.1.2 Multi-Channel Seismograph—Multi-channel seismographs use 6, 12, 24, 48 or more geophones. With a multi-channel seismograph, the seismic wave forms are recorded simultaneously for all geophones (see Fig. 3). 5.3.1.3 The simultaneous display of waveforms enables the operator to observe trends in the data and helps in making reliable picks of first arrival times. This is useful in areas that are seismically noisy and in areas with complex geologic conditions. Computer programs are available that help the interpreter pick the first arrival time. 5.3.1.4 Signal Enhancement—Signal enhancement using filtering and stacking that improve the signal to noise ratio is available in most seismographs. It is an aid when working in noisy areas or with small energy sources. Signal stacking is accomplished by adding the refracted seismic signals for a number of impacts. This process increases the signal to noise ratio by summing the amplitude of the coherent seismic signals while reducing the amplitude of the random noise by averaging. 5.3.2 Geophone and Cable:  5.3.2.1 A geophone transforms the P-wave energy into a voltage that is recorded by the seismograph. For refraction work, the frequency of the geophones varies from 8 to 14 Hz. The geophones are connected to a geophone cable that is connected to the seismograph (see Fig. 1). The geophone cable has electrical connection points (take outs) for each geophone, usually located at uniform intervals along the cable. Geophone placements are spaced from about 1 m to hundreds of meters (2 or 3 ft to hundreds of feet) apart depending upon the level of detail needed to describe the surface of the refractor and the depth of the refractor(s). The geophone intervals may be adjusted at the shot end of a cable to provide additional seismic velocity information in the shallow subsurface. 5.3.2.2 If connections between geophones and cables are not waterproof, care must be taken to assure they will not be shorted out by wet grass, rain, etc. Special waterproof geophones (marsh geophones), geophone cables and connectors are required for areas covered with shallow water. 5.3.3 Energy Sources:  5.3.3.1 The selection of seismic refraction energy sources is dependent upon the depth of investigation and geologic conditions. Four types of energy sources are commonly used in seismic refraction surveys: sledge hammers, mechanical weight drop or impact devices, projectile (gun) sources, and explosives. 5.3.3.2 For shallow depths of investigation, 5 to 10 m (15 to 30 ft), a 4 to 7 kg (10 to 15 lb) sledge hammer may be used. Three to five hammer blows using signal enhancement capabilities of the seismograph will usually be sufficient. A strike plate on the ground is used to improve the coupling of energy from the hammer to the soil. 5.3.3.3 For deeper investigations in dry and loose materials, more seismic energy is required, and a mechanized or a projectile (gun) source may be selected. Projectile sources are discharged at or below the ground surface. Mechanical seismic sources use a large weight (of about 100 to 500 lb or 45 to 225 kg) that is dropped or driven downward under power. Mechanical weight drops are usually trailer mounted because of their size. 5.3.3.4 A small amount of explosives provides a substantial increase in energy levels. Explosive charges are usually buried to reduce energy losses and for safety reasons. Burial of small amounts of explosives (less than 1 lb or 0.5 kg) at 1 to 2 m (3 to 6 ft) is effective for shallow depths of investigation (less than 300 ft or 100 m) if backfilled and tamped. For greater depths of investigation (below 300 ft or 100 m), larger explosives charges (greater than 1 lb or 0.5 kg) are required and usually are buried 2 m (6 ft) deep or more. Use of explosives requires specially-trained personnel and special procedures. 5.3.4 Timing—A timing signal at the time of impact (t = 0) is sent to the seismograph (see Fig. 1). The time of impact (t = 0) is detected with mechanical switches, piezoelectric devices or a geophone (or accelerometer), or with a signal from a blasting unit. Special seismic blasting caps should be used for accurate timing. 5.4 Limitations and Interference:  5.4.1 General Limitations Inherent to Geophysical Methods:  5.4.1.1 A fundamental limitation of all geophysical methods is that a given set of data cannot be associated with a unique set of subsurface conditions. In most situations, surface geophysical measurements alone cannot resolve all ambiguities, and some additional information, such as borehole data, is required. Because of this inherent limitation in the geophysical methods, a seismic refraction survey is not a complete assessment of subsurface conditions. Properly integrated with other geologic information, seismic refraction surveying is an effective, accurate, and cost-effective method of obtaining subsurface information. 5.4.1.2 All surface geophysical methods are inherently limited by decreasing resolution with depth. 5.4.2 Limitations Specific to the Seismic Refraction Method:  5.4.2.1 When refraction measurements are made over a layered earth, the seismic velocity of the layers are assumed to be uniform and isotropic. If actual conditions in the subsurface layers deviate significantly from this idealized model, then any interpretation also deviates from the ideal. An increasing error is introduced in the depth calculations as the angle of dip of the layer increases. The error is a function of dip angle and the velocity contrast between dipping layers (8, 9). 5.4.2.2 Another limitation inherent to seismic refraction surveys is referred to as a blind-zone problem (3, 2, 10). There must be a sufficient contrast between the seismic velocity of the overlying material and that of the refractor for the refractor to be detected. Some significant geologic or hydrogeologic boundaries have no field-measurable seismic velocity contrast across them and consequently cannot be detected with this technique. 5.4.2.3 A layer must also have a sufficient thickness in order to be detected (10). 5.4.2.4 If a layer has a seismic velocity lower than that of the layer above it (a velocity reversal), the low seismic velocity layer cannot be detected. As a result, the computed depths of deeper layers are greater than the actual depths (although the most common geologic condition is that of increasing seismic velocity with depth, there are situations in which seismic velocity reversals occur). Interpretation methods are available to address this problem in some instances (11). 5.4.3 Interferences Caused by Natural and by Cultural Conditions:  5.4.3.1 The seismic refraction method is sensitive to ground vibrations (time-variable noise) from a variety of sources. Geologic and cultural factors also produce unwanted noise. 5.4.3.2 Ambient Sources—Ambient sources of noise include any vibration of the ground due to wind, water movement (for example, waves breaking on a nearby beach), natural seismic activity, or by rainfall on the geophones. 5.4.3.3 Geologic Sources—Geologic sources of noise include unsuspected variations in travel time due to lateral and vertical variations in seismic velocity of subsurface layers (for example, the presence of large boulders within a soil). 5.4.3.4 Cultural Sources—Cultural sources of noise include vibration due to movement of the field crew, nearby vehicles, and construction equipment, aircraft, or blasting. Cultural factors such as buried structures under or near the survey line also may lead to unsuspected variations in travel time. Nearby powerlines may induce noise in long geophone cables. 5.4.3.5 During the course of designing and carrying out a refraction survey, sources of ambient, geologic, and cultural noise should be considered and its time of occurrence and location noted. The interference is not always predictable because it depends upon the magnitude of the noises and the geometry and spacing of the geophones and source. 5.5 Alternative Methods—The limitations discussed above may prevent the use of the seismic refraction method, and other geophysical or non-geophysical methods may be required to investigate subsurface conditions (see Guide D5753). 1.1 Purpose and Application—This guide covers the equipment, field procedures, and interpretation methods for the assessment of subsurface conditions using the seismic refraction method. Seismic refraction measurements as described in this guide are applicable in mapping subsurface conditions for various uses including geologic, geotechnical, hydrologic, environmental (1), mineral exploration, petroleum exploration, and archaeological investigations. The seismic refraction method is used to map geologic conditions including depth of bedrock, or the water table, stratigraphy, lithology, structure, and fractures or all of these. The calculated seismic wave velocity is related to mechanical material properties. Therefore, characterization of the material (type of rock, degree of weathering, and rippability) is made on the basis of seismic velocity and other geologic information. 1.1.1 The geotechnical industry uses English or SI units. 1.2 Limitations:  1.2.1 This guide provides an overview of the seismic refraction method using compressional (P) waves. It does not address the details of the seismic refraction theory, field procedures, or interpretation of the data. Numerous references are included for that purpose and are considered an essential part of this guide. It is recommended that the user of the seismic refraction method be familiar with the relevant material in this guide and the references cited in the text and with appropriate ASTM standards cited in 2.1. 1.2.2 This guide is limited to the commonly used approach to seismic refraction measurements made on land. The seismic refraction method can be adapted for a number of special uses, on land, within a borehole and on water. However, a discussion of these other adaptations of seismic refraction measurements is not included in this guide. 1.2.3 There are certain cases in which shear waves need to be measured to satisfy project requirements. The measurement of seismic shear waves is a subset of seismic refraction. This guide is not intended to include this topic and focuses only on P wave measurements. 1.2.4 The approaches suggested in this guide for the seismic refraction method are commonly used, widely accepted, and proven; however, other approaches or modifications to the seismic refraction method that are technically sound may be substituted. 1.2.5 Technical limitations and interferences of the seismic refraction method are discussed in D420, D653, D2845, D4428/D4428M, D5088, D5730, D5753, D6235, and D6429. 1.3 Precautions:  1.3.1 It is the responsibility of the user of this guide to follow any precautions within the equipment manufacturer's recommendations, establish appropriate health and safety practices, and consider the safety and regulatory implications when explosives are used. 1.3.2 If the method is applied at sites with hazardous materials, operations, or equipment, it is the responsibility of the user of this guide to establish appropriate safety and health practices and determine the applicability of any regulations prior to use. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this guide means only that the document has been approved through the ASTM consensus process. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 Dual-wall reverse-circulation drilling can be used in support of geoenvironmental exploration and for installation of subsurface water quality monitoring devices in unconsolidated and consolidated sediment or bedrock. Dual-wall reverse-circulation drilling methods allows for the collection of water quality samples at most depth(s), the setting of temporary casing during drilling, and continual sampling of cuttings while drilling fluid is circulating, if warranted or needed. Other advantages of the dual-wall reverse-circulation drilling method include, but are not limited to: (1) the capability of drilling without the introduction of any drilling fluid(s) (for example, drilling mud or similar) to the subsurface; (2) maintenance of borehole stability for sampling purposes and monitoring well installation/construction in poorly-indurated to unconsolidated sediment.4.1.1 The user of dual-wall reverse-circulation drilling for geoenvironmental exploration and monitoring-device installations should be cognizant of both the physical (temperature and airborne particles) and chemical (compressor lubricants and other fluid additives) qualities of compressed air that may be used as the circulating medium.4.2 The application of dual-wall reverse-circulation drilling to geoenvironmental exploration may involve soil or rock sampling, or in situ soil/sediment, rock, or pore-fluid testing.NOTE 2: The user may install a monitoring device within the same borehole wherein sampling, in situ or pore-fluid testing, or coring was performed.4.3 The subsurface water quality monitoring devices that are addressed in this guide consist generally of a screened- or porous-intake device and riser pipe(s) that are usually installed with a filter pack to enhance the longevity of the intake unit, and with isolation seals and low-permeability backfill to deter the vertical movement of fluids or infiltration of surface water between hydrologic units penetrated by the borehole (see Practice D5092). Since a piezometer is primarily a device used for measuring subsurface hydraulic heads, the conversion of a piezometer to a water quality monitoring device should be made only after consideration of the overall quality and integrity of the installation to include the quality of materials that will contact sampled water or gas. Both water quality monitoring devices and piezometers should have adequate casing seals, annular isolation seals, and backfills to deter cross-communication of contaminants between hydrogeologic units.NOTE 3: The quality of the results produced by this guide is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing. Users of this test method are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.1.1 This guide covers how dual-wall reverse-circulation drilling may be used for geoenvironmental exploration and installation of subsurface water quality monitoring devices. The term reverse circulation with respect to dual-wall drilling in this guide indicates that the circulating fluid is forced down the annular space between the double-wall drill pipe and transports soil/sediment and rock particles to the surface through the inner pipe.NOTE 1: This guide does not include considerations for geotechnical site characterizations that are addressed in a separate guide.1.2 Dual-wall reverse-circulation for geoenvironmental exploration and monitoring-device installations will often involve safety planning, administration, and documentation. This guide does not purport to specifically address exploration and site safety.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 The application of direct air-rotary drilling to geoenvironmental exploration may involve sampling, coring, in situ or pore-fluid testing, installation of casing for subsequent drilling activities in unconsolidated or consolidated materials, and for installation of subsurface water-quality monitoring devices in unconsolidated and consolidated materials. Several advantages of using the direct air-rotary drilling method over other methods may include the ability to drill rather rapidly through consolidated materials and, in many instances, not require the introduction of drilling fluids to the borehole. Air-rotary drilling techniques are usually employed to advance drill hole when water-sensitive materials (that is, friable sandstones or collapsible soils) may preclude use of water-based rotary-drilling methods. Some disadvantages to air-rotary drilling may include poor borehole integrity in unconsolidated materials without using casing, and the potential for volitization of contaminants and air-borne dust.NOTE 3: Direct-air rotary drilling uses pressured air for circulation of drill cuttings. In some instances, water or foam additives, or both, may be injected into the air stream to improve cuttings-lifting capacity and cuttings return. The use of air under high pressures may cause fracturing of the formation materials or extreme erosion of the borehole if drilling pressures and techniques are not carefully maintained and monitored. If borehole damage becomes apparent, consideration to other drilling method(s) should be given.NOTE 4: The user may install a monitoring device within the same borehole in which sampling, in situ or pore-fluid testing, or coring was performed.4.2 The subsurface water-quality monitoring devices that are addressed in this guide consist generally of a screened or porous intake and riser pipe(s) that are usually installed with a filter pack to enhance the longevity of the intake unit, and with isolation seals and a low-permeability backfill to deter the movement of fluids or infiltration of surface water between hydrologic units penetrated by the borehole (see Practice D5092). Inasmuch as a piezometer is primarily a device used for measuring subsurface hydraulic heads, the conversion of a piezometer to a water-quality monitoring device should be made only after consideration of the overall quality of the installation to include the quality of materials that will contact sampled water or gas.NOTE 5: Both water-quality monitoring devices and piezometers should have adequate casing seals, annular isolation seals, and backfills to deter movement of contaminants between hydrologic units.1.1 This guide covers how direct (straight) air-rotary drilling procedures may be used for geoenvironmental exploration and installation of subsurface water-quality monitoring devices.NOTE 1: The term direct with respect to the air-rotary drilling method of this guide indicates that compressed air is injected through a drill-rod column to a rotating bit. The air cools the bit and transports cuttings to the surface in the annulus between the drill-rod column and the borehole wall.NOTE 2: This guide does not include considerations for geotechnical site characterizations that are addressed in a separate guide.1.2 Direct air-rotary drilling for geoenvironmental exploration will often involve safety planning, administration, and documentation. This guide does not purport to specifically address exploration and site safety.1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 All observed and calculated values are to conform to the guidelines for significant digits and rounding established in Practice D6026. The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objective; and it is common practice to increase or reduce the significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis method or engineering design.1.6 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 Direct-rotary drilling may be used in support of geoenvironmental exploration and for installation of subsurface water-quality monitoring devices in unconsolidated and consolidated materials. Direct-rotary drilling may be selected over other methods based on advantages over other methods. In drilling unconsolidated sediments and hard rock, other than cavernous limestones and basalts where circulation cannot be maintained, the direct-rotary method is a faster drilling method than the cable-tool method. The cutting samples from direct-rotary drilled holes are usually as representative as those obtained from cable-tool drilled holes however, direct-rotary drilled holes usually require more well-development effort. If drilling of water-sensitive materials (that is, friable sandstones or collapsible soils) is anticipated, it may preclude use of water-based rotary-drilling methods and other drilling methods should be considered.4.1.1 The application of direct-rotary drilling to geoenvironmental exploration may involve sampling, coring, in situ or pore-fluid testing, or installation of casing for subsequent drilling activities in unconsolidated or consolidated materials. Several advantages of using the direct-rotary drilling method are stability of the borehole wall in drilling unconsolidated formations due to the buildup of a filter cake on the wall. The method can also be used in drilling consolidated formations. Disadvantages to using the direct-rotary drilling method include the introduction of fluids to the subsurface, and creation of the filter cake on the wall of the borehole that may alter the natural hydraulic characteristics of the borehole.NOTE 3: The user may install a monitoring device within the same borehole wherein sampling, in situ or pore-fluid testing, or coring was performed.4.2 The subsurface water-quality monitoring devices that are addressed in this guide consist generally of a screened or porous intake and riser pipe(s) that are usually installed with a filter pack to enhance the longevity of the intake unit, and with isolation seals and low-permeability backfill to deter the movement of fluids or infiltration of surface water between hydrologic units penetrated by the borehole (see Practice D5092/D5092M). Since a piezometer is primarily a device used for measuring subsurface hydraulic heads, the conversion of a piezometer to a water-quality monitoring device should be made only after consideration of the overall quality of the installation, including the quality of materials that will contact sampled water or gas.NOTE 4: Both water-quality monitoring devices and piezometers should have adequate casing seals, annular isolation seals and backfills to deter movement of contaminants between hydrologic units.1.1 This guide covers how direct (straight) rotary-drilling procedures with water-based drilling fluids may be used for geoenvironmental exploration and installation of subsurface water-quality monitoring devices.NOTE 1: The term direct with respect to the rotary-drilling method of this guide indicates that a water-based drilling fluid is pumped through a drill-rod column to a rotating bit. The drilling fluid transports cuttings to the surface through the annulus between the drill-rod column and the borehole wall.NOTE 2: This guide does not include considerations for geotechnical site characterization that are addressed in a separate guide.1.2 Direct-rotary drilling for geoenvironmental exploration and monitoring-device installations will often involve safety planning, administration and documentation. This standard does not purport to specifically address exploration and site safety.1.3 Units—The values stated in either SI units or inch-pound units (given in brackets) are to be regarded separately as standard. The values stated in each system may not be exactly equivalents; therefore, each system shall be used independently of the other. Combining values from the two system may result in non-conformance with the standard.1.4 All observed and calculated values are to conform to the guidelines for significant digits and rounding established in Practice D6026.1.5 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objective; and it is common practice to increase or reduce the significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis method or engineering design.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 Hollow-stem auger drilling may be used in support of geoenvironmental exploration (Practice D3550, Test Method D4428/D4428M) and for installation of subsurface water quality monitoring devices in unconsolidated sediment. Hollow-stem auger drilling may be selected over other methods based on the advantages over other methods. These advantages include: the ability to drill without the addition of drilling fluid(s) to the subsurface, and hole stability for sampling purposes (see Test Method D1586 and Practices D1587, D2487, D2488, and D6151) and monitoring well construction in unconsolidated to poorly indurated materials. This drilling method is generally restricted to the drilling of shallow, unconsolidated sediment or softer rocks. The hollow-stem drilling method is a favorable method to be used for obtaining cores and samples and for the installation of monitoring devices in many, but not every geologic environment.NOTE 2: In many geologic environments the hollow-stem auger drilling method can be used for drilling, sampling, and monitoring device installations without the addition of fluids to the borehole. However, in cases where heaving water-bearing sands or silts are encountered, the addition of water or drilling mud to the hollow-auger column may become necessary to inhibit the piping of these fluid-like materials into the augers. These drilling conditions, if encountered, should be documented.4.1.1 The application of hollow-stem augers to geoenvironmental exploration may involve groundwater and soil sampling, in situ or pore-fluid testing, or utilization of the hollow-auger column as a casing for subsequent drilling activities in unconsolidated or consolidated materials (Test Method D2113).NOTE 3: The user may install a monitoring device within the same auger borehole wherein sampling or in situ or pore-fluid testing was performed.4.1.2 The hollow-stem auger column may be used as a temporary casing for installation of a subsurface water quality monitoring device. The monitoring device is usually installed as the hollow-auger column is removed from the borehole.4.2 The subsurface water quality monitoring devices that are addressed in this guide consist generally of a screened or porous intake device and riser pipe(s) that are usually installed with a filter pack to enhance the longevity of the intake unit, and with isolation seals and low-permeability backfill to deter the movement of fluids or infiltration of surface water between hydrologic units penetrated by the borehole (see Practice D5092). A piezometer is primarily a device used for measuring subsurface hydraulic heads, the conversion of a piezometer to a water quality monitoring device should be made only after consideration of the overall quality and integrity of the installation, to include the quality of materials that will contact sampled water or gas.NOTE 4: Both water quality monitoring devices and piezometers should have adequate casing seals, annular isolation seals, and backfills to deter the movement of fluids between hydrologic units.NOTE 5: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/evaluation/and the like. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.1.1 This guide covers how hollow-stem auger-drilling systems may be used for geoenvironmental exploration and installation of subsurface water quality monitoring devices.1.2 Hollow-stem auger drilling for geoenvironmental exploration and monitoring device installations often involves safety planning, administration, and documentation. This guide does not purport to specifically address exploration and site safety.NOTE 1: This guide does not include considerations for geotechnical site characterizations that are addressed in a separate guide.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 Concepts: 5.1.1 All TDEM/TEM instruments are based on the concept that a time-varying magnetic field generated by a change in the current flowing in a large loop on the ground will cause current to flow in the earth below it (Fig. 3). In the typical TDEM/TEM system, these earth-induced currents are generated by abruptly terminating a steady current flowing in the transmitter loop (2). The currents induced in the earth material move downward and outward with time and, in a horizontally layered earth, the strength of the currents is directly related to the ground conductivity at that depth. These currents decay exponentially. The decay lasts microseconds, except in the cases of a highly conductive ore body or conductive layer when the decay can last up to a second. Hence, many measurements can be made in a short time period allowing the data quality to be improved by stacking.5.1.2 Most TDEM/TEM systems use a square wave transmitter current with the measurements taken during the off-time (Fig. 2) with the total measurement period of less than a minute. Because the strength of the signal depends on the induced current strength and secondary magnetic field, the depth of site investigation depends on the magnetic moment of the transmitter.5.1.3 A typical transient response, or receiver voltage measured, for a homogeneous subsurface (half-space) is shown in Fig. 4. The resistivity of the subsurface is obtained from the late stage response. If there are two horizontal layers with different resistivities, the response or receiver output voltage is similar to the curves shown in Fig. 5.5.2.8 Variations in temperature above freezing will affect resistivity measurements as a result of the temperature dependence of the resistivity of the pore fluid, which is of the order of 2 % per degree Celsius (1 % per degree Fahrenheit). Thus, data from measurements made in winter can be quite different from those made in summer.5.2.9 As the ground temperature decreases below freezing, the resistivity increases with decreasing temperature, slowly for fine materials (in which a significant portion of the water remains unfrozen, even at quite low temperatures), and rapidly for coarse materials (in which the water freezes immediately).5.2.10 Further information about factors that control the electrical resistivity or conductivity of different geological materials can be found in Ward 1990 (7).5.2.11 Because the TDEM/TEM technique measures subsurface resistivity, only geological or hydrological structures that cause spatial variations in resistivity are detected by this technique. If there is no resistivity contrast between the different geological materials or structures, if the resistivity contrast is too small to be detected by the instrument, or if the resistivity of the subsurface material is very high, the TDEM/TEM technique gives no useful information.5.3 Equipment—Geophysical equipment used for the TDEM/TEM method includes a transmitter, a transmitter loop of wire, a transmitter power supply, a receiver and one or more receiver coils.5.3.1 The transmitter may have power output ranging from a few watts to tens of kilowatts. Important parameters of the transmitter are that it transmits a clean wave-form (Fig. 2), and that the “turn-off” characteristics are well known and extremely stable, because they influence the initial shape of the transient response.5.3.2 The size of the transmitter power supply determines the depth of exploration, and can range from a few small batteries to a 10-kW, gasoline-driven generator.5.3.3 The transmitter loop wire is usually insulated for safety. The size of the loop and the amount of current flowing through it (and thus the diameter of the wire) determines the desired depth of exploration. The weight of the loop, which is generally stored on one or more reels, can be anywhere from a few kilograms to over 100 kg (from a few pounds to over 225 lb).5.3.4 The receiver measures the time-varying characteristic of the receiver coil output voltage at a number of points along the decay curve and stores this data in memory. Because the voltage is small, and changes rapidly with time, the receiver must have excellent sensitivity, noise rejection, linearity, stability, and bandwidth. The transmitter/receiver combination must have some facility for synchronization so that the receiver accurately records the time of transmitter current termination or variation. This synchronization is done either with an interconnecting timing cable or with high-stability quartz crystal oscillators mounted in each unit. The characteristics of a TDEM/TEM receiver and transmitter are sufficiently specialized that use of transmitters and receivers not specifically designed for TDEM/TEM by their manufacturers is not recommended.5.3.5 The receiver coil must match the characteristics of the receiver itself. It may contain a built-in preamplifier so that it can be located some distance from the receiver. The coil must be free from microphone noise, and it must be constructed so that the transient response from the metal of the coil and the coil shielding is negligible.5.4 Limitations and Interferences: 5.4.1 General Limitations Inherent to Geophysical Methods: 5.4.1.1 A fundamental limitation of all geophysical methods is that a given set of data cannot be associated with a unique set of subsurface conditions. In most situations, surface geophysical measurements alone cannot resolve all ambiguities, and additional information, such as borehole data, is required. Because of this inherent limitation in the geophysical methods, a TDEM/TEM survey alone is not considered a complete assessment of subsurface conditions. Properly integrated with other geologic information, TDEM/TEM surveying is a highly effective method of obtaining subsurface information.5.4.1.2 In addition, all surface geophysical methods are inherently limited by decreasing resolution with depth.5.4.2 Limitations Specific to the TDEM/TEM Method: 5.4.2.1 Subsurface layers are assumed horizontal within the area of measurement.5.4.2.2 A sufficient resistivity contrast between the background conditions and the feature being mapped must exist for the feature to be detected. Some significant geologic or hydrogeologic boundaries may have no field-measurable resistivity contrast across them and consequently cannot be detected with this technique.5.4.2.3 The TDEM/TEM method does not work well in highly resistive (very low conductivity) materials due to the difficulty in measuring low values of conductivity.5.4.2.4 An interpretation of TDEM/TEM data alone does not yield a unique correlation between possible geologic models and a single set of field data. This ambiguity can be significantly reduced by doing an equivalence analysis as discussed in 6.12.3 and can be further resolved through the use of sufficient supporting geologic data and by an experienced interpreter.5.4.3 Interferences Caused by Natural and Cultural Conditions: 5.4.3.1 The TDEM/TEM method is sensitive to noise from a variety of natural ambient and cultural sources. Spatial variations in resistivity caused by geologic factors may also produce noise. Cultural noise be manifested as very obviously erratic curve behavior such as in Fig. 7, or it may be subtle, repeatable, and difficult to distinguish from valid subsurface changes in resistivity.FIG. 7 Oscillations Induced in Receiver Response by Power Lines (5)5.4.3.2 Ambient Sources of Noise—Ambient sources of noise include radiated and induced responses from nearby metallic structures, and soil and rock electrochemical effects, including induced polarization. In TDEM/TEM soundings, the signal-to-noise ratio (SNR) is usually good over most of the measurement time range. However, at late times, the transient response from the ground decays extremely rapidly such that, towards the end of the transient, the signal deteriorates completely and the data become extremely noisy.5.4.3.3 Radiated and Induced Noise—Radiated noise consists of signals generated by radio, radar transmitters, and lightning. The first two are not generally a problem. However, on summer days when there is extensive local thunderstorm activity, the electrical noise from lightning strikes can cause noise problems. It may be necessary to increase the integration (stacking) time or, in severe cases, to discontinue the survey until the storms have passed by or abated.(1) The most important source of induced noise consists of intense magnetic fields arising from 50/60 Hz power lines. The large signals induced in the receiver from this source (the strength of which falls off more or less linearly with distance from the power line) can overload the receiver if the receiver gain is set too high, causing serious errors. The remedy is to reduce receiver gain to the point that overload does not occur. In some cases, this may result in less accurate measurement of the transient because the available dynamic range of the receiver is not fully utilized. Another alternative is to move the measurement array (particularly the receiver coil) further from the power line. The equipment manufacturer’s documentation may also provide information about which repetition rates or base frequencies (if any) provide the best rejection of the noise arising from power lines.(2) It was mentioned above that one of the advantages of TDEM/TEM resistivity sounding was that measurement of the transient signal from the ground was made in the absence of the primary transmitter field, since measurement is made after transmitter current turnoff (Fig. 2). Modern transmitters use extremely effective electronic switches to terminate the large transmitter current. Nevertheless very sensitive receivers can still detect small currents that linger in the loop after turn-off. The magnitude of these currents and their time behavior are available from the equipment manufacturer, who can advise the user as to how closely the receiver coil can be placed to the actual transmitter loop wire.(3) Another source of induced noise, common to ferrite or iron-cored receiver coils, is microphone noise arising from minute movements of the receiver coil in the earth's relatively strong magnetic field. Such movements are usually caused by the wind, and the coil must be shielded from the wind noise, or the measurements made at night when this source of noise is minimal. In extreme cases, it may be necessary to bury the coil.5.4.3.4 Presence of Nearby Metallic Structures—TDEM/TEM systems are excellent metal detectors. Use of such systems for resistivity sounding demands that measurements are not made in the presence of metal. This requires removal of all metallic objects not part of the survey equipment (metallic chairs, toolboxes, etc.) from the area of the survey instruments. The recommendations of the manufacturer with regard to the location of the receiver case itself with respect to the receiver coil must be followed carefully.(1) Power lines can often be detected as metallic targets as well as sources of induced noise. In this case, they exhibit an oscillatory response (the response from all other targets, including the earth, decays monotonically to zero without oscillation). Because the frequency of the oscillation is unrelated to the receiver base frequency, the effect of power line metallic response is to render the transient “noisy” (Fig. 7). Because these oscillations arise from response to eddy currents induced in the power line by the TDEM/TEM transmitter, repeating the measurement produces an identical response, which is one way that these oscillators are identified. Another way is to take a measurement with the transmitter turned off. If the noise disappears, it is a good indication that power line response is the problem. The only remedy is to move the transmitter loop further from the power line.(2) Other metallic responses, such as those from buried metallic trash or pipes can present a problem. If the response is large, another sounding site must be selected. Use of a different geophysical instrument such as a metal detector or ground conductivity meter is helpful to quickly survey the sounding site for buried metal.5.4.3.5 Geologic Sources of Noise—Geologic noise arises from the presence of unsuspected geological structures or materials, which cause variations in terrain resistivity. A rare effect that can occur in clayey soils, is induced polarization. Rapid termination of the transmitter current and thus primary magnetic field can charge up small electrical capacitors at soil particle interfaces. These capacitors subsequently discharge, producing current flow similar to that shown in Fig. 3, but reversed in direction. The net effect is to reduce the amplitude of the transient response (thus increasing the apparent resistivity) or, in severe situations, to cause the transient response to become negative over some portion of the measurement time range. Because these sources of reverse current are most significant in the vicinity of the transmitter loop, using the offset configuration (described in 6.7.1.1) usually reduces the induced polarization effect.5.5 Summary—During the course of designing and carrying out a TDEM/TEM survey, the sources of ambient, geologic and cultural noise must be considered and the time of occurrence and location noted. The form of the interference is not always predictable, as it not only depends upon the type of noise and the magnitude of the noise but upon the distance from the source of noise and possibly the time of day.5.6 Alternate Methods—In some cases, the factors discussed above may prevent the effective use of the TDEM/TEM method, and other surface geophysical methods such as conventional direct current (DC) resistivity sounding (Guide D6431), frequency domain electromagnetic surveying (Guide D6639) or non-geophysical methods may be required to investigate subsurface conditions.1.1 Purpose and Application: 1.1.1 This guide is one in a series of documents that describe geophysical site investigation methods.1.1.2 This guide summarizes the equipment, field procedures, and interpretation methods for the assessment of subsurface materials and their pore fluids using the Time Domain Electromagnetic (TDEM) method. This method is also known as the Transient Electromagnetic (TEM) Method, and in this guide is referred to as the TDEM/TEM method. Time Domain and Transient refer to the measurement of a time-varying induced electromagnetic field.1.1.3 The TDEM/TEM method is applicable to the subsurface site investigation for a wide range of conditions. TDEM/TEM methods measure variations in the electrical resistivity (or the reciprocal, the electrical conductivity) of the subsurface soil or rock caused by both lateral and vertical variations in various physical properties of the soil or rock. By measuring both lateral and vertical changes in resistivity, variations in subsurface conditions can be determined.1.1.4 Electromagnetic measurements of resistivity as described in this guide are applied in geologic studies, geotechnical studies, hydrologic site investigations, and for mapping subsurface conditions at waste disposal sites (1).2 Resistivity measurements can be used to map geologic changes such as lithology, geological structure, fractures, stratigraphy, and depth to bedrock. In addition, measurement of resistivity can be applied to hydrologic site investigations such as the depth to water table, depth to aquitard, presence of coastal or inland groundwater salinity, and for the direct exploration for groundwater.1.1.5 This standard does not address the use of TDEM/TEM method for use as metal detectors or their use in unexploded ordnance (UXO) detection and characterization. While many of the principles apply the data acquisition and interpretation differ from those set forth in this standard guide.1.1.6 General references for the use of the method are McNeill (2), Kearey and Brooks (3), and Telford et al (4).1.2 Limitations: 1.2.1 This guide provides an overview of the TDEM/TEM method. It does not provide or address the details of the theory, field procedures, or interpretation of the data. Numerous references are included for that purpose and are considered an essential part of this guide. It is recommended that the user of the TDEM/TEM method be familiar with the references cited and with the ASTM standards D420, D653, D5088, D5608, D5730, D5753, D6235, D6429 and D6431.1.2.2 This guide is limited to TDEM/TEM measurements made on land. The TDEM/TEM method can be adapted for a number of special uses on land, water, ice, within a borehole, and airborne. Special TDEM/TEM configurations are used for metal and unexploded ordnance detection. These TDEM/TEM methods are not discussed in this guide.1.2.3 The approaches suggested in this guide for the TDEM/TEM method are commonly used, widely accepted, and proven. However, other approaches or modifications to the TDEM/TEM method that are technically sound may be substituted.1.2.4 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education, experience, and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word standard in the title of this document means only that the document has been approved through the ASTM consensus process.1.3 Precautions: 1.3.1 It is the responsibility of the user of this guide to follow any precautions in the equipment manufacturer's recommendations and to establish appropriate health and safety practices.1.3.2 If the method is used at sites with hazardous materials, operations, or equipment, it is the responsibility of the user of this guide to establish appropriate safety and health practices and to determine the applicability of any regulations prior to use.1.3.3 This guide does not purport to address all of the safety concerns that may be associated with the use of the TDEM/TEM method. It must be emphasized that potentially lethal voltages exist at the output terminals of many TDEM/TEM transmitters, and also across the transmitter loop, which is sometimes uninsulated. It is the responsibility of the user of this equipment to assess potential environmental safety hazards resulting from the use of the selected equipment, establish appropriate safety practices and to determine the applicability of regulations prior to use.1.3.4 Units—The values stated in SI units are regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units, which are provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this guide.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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This specification covers requirements and test methods for annular, corrugated profile wall polyethylene pipe and fittings with an interior liner. The pipe and blow-molded fittings shall be made of virgin PE plastic compound having a cell classification 435400C or 435400 and its carbon black content shall not exceed 4 %. Compounds used in the manufacture of rotationally molded fittings and couplings shall be virgin PE having a cell classification of 213320C or 213320E and its carbon black content shall not exceed 4%. On the other hand, compounds used in the manufacture of injection molded fittings and couplings shall be made of virgin PE plastic compound having a cell classification 414420C or 414420E and its carbon black content shall not exceed 4 %. Different tests and measurements shall be performed in order to determine the following properties of pipes: inside diameter, length, minimum inner-liner thickness, perforations, stiffness, flattening, and impact resistance. The pipe and fittings shall be homogeneous throughout and be as uniform as commercially practical in color, opacity, and density. The pipe walls shall be free of cracks, holes, blisters, voids, foreign inclusions, or other defects that are visible to the naked eye and that may affect the wall integrity. The ends shall be cut cleanly and squarely. Holes intentionally placed in perforated pipe are acceptable.1.1 This specification covers requirements and test methods for annular, corrugated profile wall polyethylene pipe and fittings with an interior liner. The nominal inside diameters covered are 300 mm to 1500 mm [12 in. to 60 in.].1.2 The requirements of this specification are intended to provide pipe and fittings for underground use for non-pressure gravity-flow storm sewer and subsurface drainage systems.NOTE 1: Pipe and fittings produced in accordance with this specification shall be installed in compliance with Practice D2321.1.3 This specification covers pipe and fittings with an interior liner using a corrugated exterior profile (Fig. 1).FIG. 1 Typical Annular Corrugated Pipe Profile1.4 The products manufactured under this standard use either virgin or recycled (post-industrial or post-consumer) materials in accordance with the requirements specified for each.1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.6 The following precautionary caveat pertains only to the test method portion, Section 7, of this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 Concepts: 5.1.1 This guide summarizes the basic equipment, field procedures, and interpretation methods used for detecting, delineating, or mapping shallow subsurface features and relative changes in layer geometry or stratigraphy using the seismic-reflection method. Common applications of the method include mapping the top of bedrock, delineating bed or layer geometries, identifying changes in subsurface material properties, detecting voids or fracture zones, mapping faults, defining the top of the water table, mapping confining layers, and estimating of elastic-wave velocity in subsurface materials. Personnel requirements are as discussed in Practice D3740.5.1.2 Subsurface measurements using the seismic-reflection method require a seismic source, multiple seismic sensors, multi-channel seismograph, and appropriate connections (radio or hardwire) between each (Fig. 1, also showing optional roll-along switch).Seismic energy propagation time between seismic sensors depends on wave type, travel path, and seismic velocity of the material. The travel path of reflected body waves (compressional (P) and shear (S) waves) is controlled by subsurface material velocity and geometry of interfaces defined by acoustic impedance (product of velocity and density) changes. A difference in acoustic impedance between two layers results in an impedance contrast across the boundary separating the layers and determines the reflectivity (reflection coefficient) of the boundary; for example, how much energy is reflected versus how much is transmitted (Eq 3). At normal incidence:where:R   =   reflectivity = reflection coefficient,V1V2   =   velocity of layers 1 and 2,ρ1ρ2   =   density of layers 1 and 2,Vρ   =   acoustic impedance, andA   =   impedance contrast.Snell’s law (Eq 4) describes the relationship between incident, refracted, and reflected seismic waves:where:i   =   incident angle,r   =   reflected angle, andt   =   refracted angle.At each boundary represented by a change in the product of velocity and density (acoustic impedance), the incident seismic wave generates a reflected P, reflected S, transmitted P, and transmitted S wave. This process is described by the Zoeppritz equations (for example, Telford et al. (4)).5.1.3.2 Analysis and recognition of seismic energy arrival patterns at different seismic sensors allows estimation of depths to reflection coefficients (reflectors) and average velocity between the reflection coefficient and the earth’s surface. Analog display of the seismic waves recorded by each seismic sensor is generally in wiggle trace format on the seismogram (Fig. 2) and represents the particle motion (velocity or acceleration) consistent with the orientation and type of the seismic sensor (geophone or accelerometer) and source.(A) Velocities are mean for a range appropriate for the material (5).(B) Acoustic impedance is velocity multiplied by density, specifically for compressional waves; the equivalent for shear waves is referred to as seismic impedance (units of kg/s·m 2).(C) Subsonic velocities have been reported by researchers studying the ultra-shallow near surface .(A) Layer 1 on Fig. 1.(B) Layer 2 on Fig. 1.(C) R in Eq 3, Absolute value R = 1 total reflectance.5.2.1 The seismic-reflection method images changes in the acoustic (seismic) impedance of subsurface layers and features, which represent changes in subsurface material properties. While the seismic reflection technique depends on the existence of non-zero reflection coefficients, it is the interpreter who, based on knowledge of the local conditions and other data, must interpret the seismic-reflection data and arrive at a geologically feasible solution. Changes in reflected waveform can be indicative of changes in the subsurface such as lithology (rock or soil type), rock consistency (that is, fractured, weathered, competent), saturation (fluid or gas content), porosity, geologic structure (geometric distortion), or density (compaction).5.2.2 Reflection Coefficient or Reflectivity—Reflectivity is a measure of energy expected to return from a boundary (interface) between materials with different acoustic impedance values. Materials with larger acoustic impedances overlying materials with smaller acoustic impedances will result in a negative reflectivity and an associated phase reversal of the reflected wavelet. Intuitively, wavelet polarity follows reflection coefficients that are negative when faster or denser layers overlie slower or less dense (for example, clay over dry sand) layers and positive when slower or less dense layers overlie faster or denser (for example, gravel over limestone) layers. A reflectivity of one means all energy will be reflected at the interface.5.3 Equipment—Geophysical equipment used for surface seismic measurement can be divided into three general categories: source, seismic sensors, and seismograph. Sources generate seismic waves that propagate through the ground as either an impulsive or a coded wavetrain. Seismic sensors can measure changes in acceleration, velocity, displacement, or pressure. Seismographs measure, convert, and save the electric signal from the seismic sensors by conditioning the analog signal and then converting the analog signal to a digital format (A/D). These digital data are stored in a predetermined standardized format. A wide variety of seismic surveying equipment is available and the choice of equipment for a seismic reflection survey should be made to meet the objectives of the survey.5.3.1 Sources—Seismic sources come in two basic types: impulsive and coded. Impulsive sources transfer all their energy (potential, kinetic, chemical, or some combination) to the earth instantaneously (that is, usually in less than a few milliseconds). Impulsive source types include explosives, weight drops, and projectiles. Coded sources deliver their energy over a given time interval in a predetermined fashion (swept frequency or impulse modulated as a function of time). Source energy characteristics are highly dependent on near-surface conditions and source type (6-9). Consistent, broad bandwidth source energy performance is important in seismic reflection surveying. The primary measure of source effectiveness is the measure of signal-to-noise ratio and resolution potential as estimated from the recorded signal.5.3.1.1 Selection of the seismic source should be based upon the objectives of the survey, site surface and geologic conditions and limitations, survey economics, source repeatability, previous source performance, total energy and bandwidth possible at survey site (based on previous studies or site specific experiments), and safety.5.3.1.2 Coded seismic sources will generally not disturb the environment as much as impulsive sources for a given total amount of seismic energy. Variable amplitude background noise (such as passing cars, airplanes, pedestrian traffic, etc.) affects the quality of data collected with coded sources less than for impulsive sources. Coded sources require an extra processing step to compress the time-variable signal wavetrain down to a more readily interpretable pulse equivalent. This is generally done using correlation or shift and stack techniques.5.3.1.3 In most settings, buried small explosive charges will result in higher frequency and broader bandwidth data, in comparison to surface sources. However, explosive sources generally come with use restrictions, regulations, and more safety considerations than other sources. Most explosive and projectile sources are designed to be invasive, while weight drop and most coded sources are generally in direct contact with the ground surface and therefore are non-invasive.5.3.1.4 Sources that shake, impact, or drive the ground so that the dominant particle motion is horizontal to the surface of the ground are shear-wave sources. Sources that shake, impact, or drive the ground so that the dominant particle motion is vertical to the surface of the ground are compressional sources. Many sources can be used for generating both shear and compressional wave energy.5.3.2 Seismic Sensors—Seismic sensors convert mechanical particle motion to electric signals. There are three different types of seismic sensors: accelerometers, geophones (occasionally referred to as seismometers), and hydrophones.5.3.2.1 Accelerometers are devices that measure particle acceleration. Accelerometers generally require pre-amplifiers to condition signal prior to transmission to the seismograph. Accelerometers generally have a broader bandwidth of sensitivity and a greater tolerance for high G-forces than geophones or hydrophones. Accelerometers have a preferred direction of sensitivity.5.3.2.2 Geophones consist of a stationary cylindrical magnet surrounded by a coil of wire that is attached to springs and free to move relative to the magnet. Geophones measure particle velocity and therefore produce a signal that is the derivative of the acceleration measured by accelerometers. Geophones are generally robust, durable, and have unique response characteristics proportional to their natural frequency and coil impedance. The natural frequency is related to the spring constant and the coil impedance is a function of the number of wire windings in the coil.5.3.2.3 Hydrophones are used when measuring seismic signals propagating in liquids. Because shear waves are not transmitted through water, hydrophones only respond to compressional waves. However, shear waves can be converted to compressional waves at the water/earth interface and provide an indirect measurement of shear waves. Hydrophones are pressure-sensitive devices that are usually constructed of one or more piezoelectric elements that distort with pressure.5.3.2.4 Geophones and accelerometers can be used for compressional or shear wave surveys on land. Orientation of the seismic sensor determines the seismic sensor response and sensitivity to different particle motion. Some seismic sensors are omnidirectional and are sensitive to particle motion parallel to the motion axis of the sensor, regardless of the sensor’s spatial orientation direction. Others seismic sensors are designed to be used in one orientation or the other (P or S). Shear wave seismic sensors are sensitive to particle motion perpendicular to the direction of propagation (line between source and seismic sensors) and are sensitive to vertical (SV) or horizontal (SH) transverse wave motion. Compressional wave seismic sensors are sensitive to particle motion parallel to the direction of propagation (line between source and seismic sensor) and thus the motion axis of the seismic sensor needs to be in a vertical position.5.3.3 Seismographs—Seismographs measure the voltages generated by seismic sensors as a function of time and synchronize them with the seismic source. Seismographs have differing numbers of channels and a range of electronic specifications. The choice of an appropriate seismograph should be based on survey objectives. Modern multichannel seismographs are computer based and require minimal fine-tuning to adjust for differences or changes in site characteristics. Adjustable seismograph acquisition settings that will affect the accuracy or quality of recorded data are generally limited to sampling rate, record length, analog filter settings, pre-amplifier gains, and number of recording channels. There is limited need for selectable analog filters and gain adjustments with modern, large dynamic range (>16 bits) seismographs. Seismographs store digital data in standard formats (for example, SEGY, SEGD, SEG2) that are generally dependent on the type of storage medium and the primary design application of the system. Seismographs can be single units (centralized), with all recording channels (specifically analog circuitry and A/D converters) at a single location, or several autonomous seismographs can be distributed around the survey area. Distributed seismographs are characterized by several small decentralized digitizing modules (1–24 channels each) located close to the geophones to reduce signal loss over long-cable seismic sensors. Digital data from each distributed module are transmitted to a central system where data from multiple distributed units are collected, cataloged, and stored.5.3.4 Source and Seismic Sensor Coupling—The seismic sensors and sources must be coupled to the ground. Depending on ground conditions and source and seismic sensor configuration, this coupling can range from simply resting on the ground surface (for example, land streamers, weight drop, vibrator) to invasive ground penetration or burial (for example, spike, buried explosives, projectile delivery at bottom of a hole). Hydrophones couple to the ground through submersion in water in a lake, stream, borehole, ditch, etc.5.3.5 Supporting Components—Additional equipment includes a roll-along switch, cables, time-break system (radio or hardwire telemetry between seismograph and source), quality control (QC) and troubleshooting equipment (seismic sensor continuity, earth leakage, cable leakage, seismograph distortion and noise thresholds, cable and seismic sensor shorting plug), and land surveying equipment.5.4 Limitations and Interferences: 5.4.1 General Limitations Inherent to Geophysical Methods: 5.4.1.1 A fundamental limitation of all geophysical methods is that a given set of data does not uniquely represent a set of subsurface conditions. Geophysical measurements alone cannot uniquely resolve all ambiguities, and some additional information, such as borehole measurements, is required. Because of this inherent limitation in geophysical methods, a seismic-reflection survey will not completely represent subsurface geological conditions. Properly integrated with other geologic information, seismic-reflection surveying can be an effective, accurate, and cost-effective method of obtaining detailed subsurface information. All geophysical surveys measure physical properties of the earth (for example, velocity, conductivity, density, susceptibility) but require correlation to the geology and hydrology of a site. Reflection surveys do not directly measure material-specific characteristics (such as color, texture, and grain size), or lithologies (such as limestone, shale, sandstone, basalt, or schist), except to the extent that these lithologies may have different velocities and densities.5.4.1.2 All surface geophysical methods are inherently limited by signal attenuation and decreasing resolution with depth.5.4.2 Limitations Specific to the Seismic-Reflection Method: 5.4.2.1 Theoretical limitations of the seismic-reflection method are related to the presence of a non-zero reflection coefficient, seismic energy characteristics, seismic properties (velocity and attenuation), and layer geometries relative to recording geometries. In a homogenous earth, no reflections are produced and therefore none can be recorded. When reflection measurements are made at the surface of the earth, reflections can only be returned from within the earth if layers with non-zero reflection coefficients are present within the earth. Layers, for example, defined by changes in lithology without measurable changes in either velocity or density cannot be imaged with the seismic reflection method. Theoretical limits on bed or object-resolving capabilities of a seismic data set are related to frequency content of the reflected energy (see 8.4).5.4.2.2 Successful imaging of geologic layers dipping at greater than 45 degrees may require non-standard deployments of sources and seismic sensors.5.4.2.3 Resolution (discussed in 8.4) and signal-to-noise ratios are critical factors in determining the practical limitations of the seismic-reflection method. Source configuration, source and seismic sensor coupling, near-surface materials, specification of the recording systems, relative amplitude of seismic events, and arrival geometry of coherent source-generated seismic noise are all factors in defining the practical limitations of seismic-reflection method.(1) Highly attenuative near-surface materials such as dry sand and gravel, can adversely affect the resolution potential and signal strength with depth of seismic energy (10). Attenuation is rapid reduction of seismic energy as it propagates through an earth material, usually most pronounced at high frequencies. Attenuative materials can prevent survey objectives from being met.(2) While it is possible to enhance signal not visible on raw field data, it is safest to track all coherent events on processed seismic reflection sections from raw field data through all processing steps to CMP stack. Noise can be processed to appear coherent on CMP stacked sections.(3) Differences in water quality do not appear to change the velocity and density sufficiently that they can be detected by the seismic-reflection method (11).5.4.3 Interferences Caused by Natural and by Cultural Conditions: 5.4.3.1 The seismic-reflection method is sensitive to mechanical and electrical noise from a variety of sources. Biologic, geologic, atmospheric, and cultural factors can all produce noise.(1) Biologic Sources—Biologic sources of noise include vibrations from animals both on the ground surface and underground in burrows as well as trees, weeds, and grasses shaking from wind. Examples of animals that can cause noise include mice, lizards, cattle, horses, dogs, and birds. Animals, especially livestock, can produce seismic vibrations several orders of magnitude greater than seismic signals at longer offset traces on high-resolution data.(2) Geologic Sources—Geologic sources of noise include rockslides, earthquakes, scattered energy from fractures, faults or other discontinuities, and moving water (for example, water falls, river rapids, water cascading in wells).(3) Atmospheric Sources—Atmospheric sources of noise include wind shaking seismic sensors or cables, lightning, rain falling on seismic sensors, snow accumulations melting and falling from trees and roofs, and wind shaking surface structures (for example, buildings, poles, signs).(4) Cultural Sources—Cultural sources of noise include power lines (that is, 50 Hz, 60 Hz, and related harmonics), vehicles (for example, cars, motorcycles, trains, planes, helicopters, ATVs), air conditioners, lawn mowers, small engine-powered tools, construction equipment, and people—both crew members and pedestrians—moving in proximity to the seismic line. Radio Frequency (RF) and other electromagnetic (EM) signals transmitted from radar installations, radio transmitters, or beacons can appear on seismic data at amplitudes several times larger than source-generated seismic signals.5.4.3.2 During the design and operation of a seismic reflection survey, sources of biologic, geologic, atmospheric, and cultural noise and their proximity to the survey area should be considered, especially the characteristic of the noise and size of the area affected by the noise. The interference of each is not always predictable because of unknowns associated with earth coupling and energy attenuation.5.4.4 Interference Caused by Source-Generated Noise: 5.4.4.1 Seismic sources generate both signal and noise. Signal is any energy that is to be used to interpret subsurface conditions. Noise is any recorded energy that is not used to interpret subsurface conditions or diminishes the interpretability of signal. Ground roll (surface waves), direct waves, refractions, diffractions, air-coupled waves, and reflection multiples are all common types of source-generated noise observed on a seismogram recorded during seismic reflection profiling (Fig. 3).FIG. 3 Gained Field Records from Two Different Positions on One Seismic LineNOTE 1: The reflection arrivals are shown on both records.(1) Ground Roll—Ground roll is a type of surface wave that appears on a reflection seismogram (see Figs. 2 and 3). Ground roll is generated by the source and propagates along the ground surface as a lower velocity, higher amplitude, dispersive wave. Ground roll can dominate near-offset seismic sensors, making separation of reflections at close offsets difficult. Ground roll can be misinterpreted as reflection arrivals, especially if the incorrect offsets or geophone interval are used.(2) Direct Waves—The seismic energy arriving first in time at the sensors closest to the source is known as the direct wave. Direct waves are body waves that travel directly from the source seismic sensor through the uppermost layer of the earth.(3) Refractions—Refracted seismic energy travels along a velocity contrast (contact separating two different materials) returning to the surface at an angle related to the velocity above and below the contrast and with a linear phase velocity equal to the seismic velocity of the material below the velocity contrast. Refractions are generally the first (in time) coherent seismic energy to arrive at a sensor, beginning a source-to-sensor offset beyond those where direct wave energy arrives first. For a more detailed discussion of refractions and their use as a geophysical imaging tool, see Guide D5777.(4) Diffraction—Diffractions are energy scattered from discontinuous subsurface layers (faults, fractures) or points where subsurface layers or objects terminate (lens, channel, boulder). Diffractions are generally considered seismic noise when undertaking a reflection survey.(5) Air-coupled Waves—Air-coupled waves are sound waves traveling through the air, exciting the ground near the seismic sensor and then recorded by the seismic sensor. Air waves generated by the source arrive on seismograms with a linear velocity (distance from source¸ arrival time) of ~330 m/s (velocity of sound in air). Cultural noise generated by aircraft is a form of air-coupled wave. Air-coupled waves can reflect from surface objects and in some cases appear very similar to reflections from layers within the earth on seismograms. Air-coupled waves can alias to produce false trace-to-trace coherency and be misinterpreted as reflections.(6) Reflection Multiples—Reflection multiples are reflections that reverberate between several layers in the subsurface. Multiple reflections or reverberations between layers are reflections and therefore appear on seismograms with all the characteristics of reflections. Multiples can best be distinguished by their arrival pattern and cyclic nature on seismograms and their lower than expected normal move-out velocity.5.5 Alternative Methods—Limitations discussed above may preclude the use of the seismic-reflection method. Other geophysical (see Guide D6429) or non-geophysical methods may be required to investigate subsurface conditions when signal-to-noise ratio is too low or the resolution potential is insufficient for the survey objectives.1.1 Purpose and Application: 1.1.1 This guide summarizes the technique, equipment, field procedures, data processing, and interpretation methods for the assessment of shallow subsurface conditions using the seismic-reflection method.1.1.2 Seismic reflection measurements as described in this guide are applicable in mapping shallow subsurface conditions for various uses including geologic (1), geotechnical, hydrogeologic (2), and environmental (3).2 The seismic-reflection method is used to map, detect, and delineate geologic conditions including the bedrock surface, confining layers (aquitards), faults, lithologic stratigraphy, voids, water table, fracture systems, and layer geometry (folds). The primary application of the seismic-reflection method is the mapping of lateral continuity of lithologic units and, in general, detection of change in acoustic properties in the subsurface.1.1.3 This guide will focus on the seismic-reflection method as it is applied to the near surface. Near-surface seismic reflection applications are based on the same principles as those used for deeper seismic reflection surveying, but accepted practices can differ in several respects. Near-surface seismic-reflection data are generally high-resolution (dominant frequency above 80 Hz) and image depths from around 6 m to as much as several hundred meters. Investigations shallower than 6 m have occasionally been undertaken, but these should be considered experimental.1.2 Limitations: 1.2.1 This guide provides an overview of the shallow seismic-reflection method, but it does not address the details of seismic theory, field procedures, data processing, or interpretation of the data. Numerous references are included for that purpose and are considered an essential part of this guide. It is recommended that the user of the seismic-reflection method be familiar with the relevant material in this guide, the references cited in the text, and Guides D420, D653, D2845, D4428/D4428M, Practice D5088, Guides D5608, D5730, D5753, D6235, and D6429.1.2.2 This guide is limited to two-dimensional (2-D) shallow seismic-reflection measurements made on land. The seismic-reflection method can be adapted for a wide variety of special uses: on land, within a borehole, on water, and in three dimensions (3-D). However, a discussion of these specialized adaptations of reflection measurements is not included in this guide.1.2.3 This guide provides information to help understand the concepts and application of the seismic-reflection method to a wide range of geotechnical, engineering, and groundwater problems.1.2.4 The approaches suggested in this guide for the seismic-reflection method are commonly used, widely accepted, and proven; however, other approaches or modifications to the seismic-reflection method that are technically sound may be equally suited.1.2.5 Technical limitations of the seismic-reflection method are discussed in 5.4.1.2.6 This guide discusses both compressional (P) and shear (S) wave reflection methods. Where applicable, the distinctions between the two methods will be pointed out in this guide.1.3 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This guide is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration for a project’s many unique aspects. The word “Standard” in the title of this guide means only that the document has been approved through the ASTM consensus process.1.4 The values stated in SI units are regarded as standard. The values given in parentheses are inch-pound units, which are provided for information only and are not considered standard.1.5 Precautions: 1.5.1 It is the responsibility of the user of this guide to follow any precautions within the equipment manufacturer’s recommendations, establish appropriate health and safety practices, and consider the safety and regulatory implications when explosives or any high-energy (mechanical or chemical) sources are used.1.5.2 If the method is applied at sites with hazardous materials, operations, or equipment, it is the responsibility of the user of this guide to establish appropriate safety and health practices and determine the applicability of any regulations prior to use.1.5.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 Uses—The requirements of this practice are intended to provide manholes suitable for installation in pipeline or conduit trenches, landfill perimeters, and landfills with limited settlement characteristics. Direct installation in sanitary landfills or other fills subject to large (in excess of 10 %) soil settlements may require special designs outside the scope of this practice.4.1.1 Manholes are assumed to be subject to gravity flow only.4.2 Design Assumption—The design methodology in this practice applies only to manholes that are installed in backfill consisting of Class I, Class II, or Class III material as defined in Practice D2321, which has been compacted to a minimum of 90 % standard proctor density. The designs are based on the backfill extending at least 3.5 ft (1 m) from the perimeter of the manhole for the full height of the manhole and extending laterally to undisturbed in situ soil. Manholes are assumed placed on a stable base consisting of at least 12 in. (30.5 cm) of Class I material compacted to at least 95 % standard proctor density or a concrete slab. The foundation soils under the base must provide adequate bearing strength to carry downdrag loads.4.2.1 Manholes installed in sanitary landfills or other fills experiencing large settlements may require special designs beyond the scope of this practice. The designer should evaluate each specific site to determine the suitability for use of HDPE manholes and the designer should prepare a written specification for installation, which is beyond the scope of this practice.1.1 This practice covers general and basic procedures related to the design of manholes and components manufactured from high-density polyethylene (HDPE) for use in subsurface applications and applies to personnel access structures. The practice covers the material, the structural design requirements of the manhole barrel (also called vertical riser or shaft), floor (bottom), and top, and joints between shaft sections.1.2 This practice offers the minimum requirements for the proper design of an HDPE manhole. Due to the variability in manhole height, diameter, and the soil, each manhole must be designed and detailed individually. When properly used and implemented, this practice can help ensure a safe and reliable structure for the industry.1.3 Disclaimer—The reader is cautioned that independent professional judgment must be exercised when data or recommendations set forth in this practice are applied. The publication of the material contained herein is not intended as a representation or warranty on the part of ASTM that this information is suitable for general or particular use, or freedom from infringement of any patent or patents. Anyone making use of this information assumes all liability arising from such use. The design of structures is within the scope of expertise of a licensed architect, structural engineer, or other licensed professional for the application of principles to a particular structure.1.4 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are provided for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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In geotechnical, hydrologic, and waste-management investigations, it is frequently desirable, or required, to obtain information concerning the presence of ground water or other liquids and the depths to the ground-water table or other liquid surface. Such investigations typically include drilling of exploratory boreholes, performing aquifer tests, and possibly completion as a monitoring or observation well. The opportunity exists to record the level of liquid in such boreholes or wells, as the boreholes are being advanced and after their completion.Conceptually, a stabilized borehole liquid level reflects the pressure of ground water or other liquid in the earth material exposed along the sides of the borehole or well. Under suitable conditions, the borehole liquid level and the ground-water, or other liquid, level will be the same, and the former can be used to determine the latter. However, when earth materials are not exposed to a borehole, such as material which is sealed off with casing or drilling mud, the borehole water levels may not accurately reflect the ground-water level. Consequently, the user is cautioned that the liquid level in a borehole does not necessarily bear a relationship to the ground-water level at the site.The user is cautioned that there are many factors which can influence borehole liquid levels and the interpretation of borehole liquid-level measurements. These factors are not described or discussed in this test method. The interpretation and application of borehole liquid-level information should be done by a trained specialist.Installation of piezometers should be considered where complex ground-water conditions prevail or where changes in intergranular stress, other than those associated with fluctuation in water level, have occurred or are anticipated.1.1 This test method describes the procedures for measuring the level of liquid in a borehole or well and determining the stabilized level of liquid in a borehole.1.2 The test method applies to boreholes (cased or uncased) and monitoring wells (observation wells) that are vertical or sufficiently vertical so a flexible measuring device can be lowered into the hole.1.3 Borehole liquid-level measurements obtained using this test method will not necessarily correspond to the level of the liquid in the vicinity of the borehole unless sufficient time has been allowed for the level to reach equilibrium position.1.4 This test method generally is not applicable for the determination of pore-pressure changes due to changes in stress conditions of the earth material.1.5 This test method is not applicable for the concurrent determination of multiple liquid levels in a borehole.1.6 The values stated in inch-pound units are to be regarded as the standard.1.7 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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5.1 Concepts: 5.1.1 This guide summarizes the equipment, field procedures and interpretation methods used for the characterization of subsurface materials and geological structure as based on their properties to conduct, enhance or obstruct the flow of electrical currents as induced in the ground by an alternating electromagnetic field.5.1.2 The frequency domain method requires a transmitter or energy source, a transmitter coil, receiver electronics, a receiver coil, and interconnect cables (Fig. 5).Perhaps the most important constraint is that the depth of penetration (skin depth, see section 6.5.3.1) of the electromagnetic wave generated by the transmitter be much greater than the intercoil spacing of the instrument. The depth of penetration is inversely proportional to the ground conductivity and instrument frequency. For example, an instrument with an intercoil spacing of 10 m and a frequency of 6400 Hz, using the vertical dipole, meets the low induction number assumption for earth conductivities less than 200 mS/m.5.1.5 Multi-frequency domain instruments usually measure the two components of the secondary magnetic field: a component in-phase with the primary field and a component 90° out-of-phase (quadrature component) with the primary field (Kearey and Brook 1991). Generally, instruments do not display either the in-phase or out-of-phase (quadrature) components but do show either the apparent conductivity or the ratio of the secondary to primary magnetic fields.5.1.6 When ground conditions are such that the low induction number approximation is valid, the in-phase component is much less than the quadrature phase component. If there is a relatively large in-phase component, the low induction number approximation is not valid and there is likely a very conductive buried body or layer, that is, ore body or man-made metal object.5.1.7 The transmitter and receiver coils are almost always aligned in a plane either parallel to the earth's surface (axis of the coils vertical) and generally called the vertical dipole (VD) mode or aligned in a plane perpendicular to the earth surface (axis of the coils horizontal) generally called the horizontal dipole (HD) mode (Fig. 3).5.1.8 The vertical and horizontal dipole orientations measure distinctly different responses to the subsurface material (Fig. 2). When these vertical and horizontal dipole mode measurements are made with several intercoil spacings or appropriate frequencies, they can be combined to resolve multiple earth layers of varying conductivities and thicknesses. This FDEM method is generally limited to only 2 or 3 layers with good resolution of depth and conductivity and only if there is a strong conductivity contrast between layers that are relatively thick and relatively shallow (in terms of the intercoil spacing).5.1.9 The conductivity value obtained in 5.1.4 is referred to as the apparent conductivity σa. For a homogeneous and isotropic earth or half space (in which no layering is present), the apparent conductivity will be the same for both the measurements. Since the horizontal dipole (HD) is more sensitive to the near surface material than the vertical dipole (VD), these two measurements can be used together to tell whether the conductivity is increasing or decreasing with depth.5.1.10 For instruments referred to as Ground Conductivity Meters (GCMs), the system parameters and constants in 5.1.4 are included in the measurement process, giving a calculated reading of σa, usually in mS/m. In some instruments, the ratio of the in-phase components of the secondary to primary magnetic fields (Hs/Hpp) is displayed in ppt (parts per thousand).5.1.11 For other frequency domain instruments, the measurements for both the in-phase and quadrature phase of the secondary magnetic field are given as ratios.5.1.12 For a homogeneous horizontally layered earth, the measured apparent conductivity calculated by the instrument is the sum of each layer's conductivity weighted by the appropriate HD or VD response function (Fig. 2).5.1.13 When the subsurface is not homogeneous or horizontally layered (such as when there is a geologic anomaly or man-made object present), the apparent conductivity may not be representative of the bulk conductivity of the subsurface material. Some anomalous features can, because of their orientation relative to the instrument coils, produce a negative apparent conductivity. While this negative value is not valid as a conductivity measurement, it is an indication of the presence of a geologic anomaly or buried object.5.1.14 Many common geologic features such as fracture zones, buried channels, dikes and faults, and man-made buried objects, can be detected and identified by relatively well-known anomalous survey signatures (Fig. 3).5.2 Parameters Measured and Representative Values: 5.2.1 The FDEM method provides a measure of the apparent electrical conductivity of the subsurface materials. For ground conductivity meters (GCMs), this apparent conductivity is read or recorded directly. For instruments not using the “low induction number approximation” the measurement is given by the ratio of the secondary magnetic field to the primary magnetic field (Hs/Hp).5.2.2 Some GCMs also give an in-phase measurement corresponding to the in-phase component of the secondary magnetic field in parts per thousand (ppt) of the primary field. The in-phase component is especially useful for mineral exploration, detecting buried man-made metallic objects, or for measuring the soil or rock magnetic susceptibility and verifying the assumption that the subsurface is nonmagnetic (McNeill, 1983).5.2.3 Fig. 6 shows the electrical conductivities for typical earth materials varying over five decades from 0.01 mS/m to a few thousand mS/m. Even a specific earth material (Fig. 6) can have a large variation in conductivity, which is related to its temperature, particle size, porosity, pore fluid saturation, and pore fluid conductivity. Some of these variations, such as a conductive contaminant pore fluid, may be detected by the FDEM method.FIG. 6 Earth Material Conductivity Ranges (Sheriff, 1991)5.3 Equipment: 5.3.1 The FDEM equipment consists of a transmitter electronics and transmitter coil, a receiver electronics and receiver coil, and interconnect cables. Generally these vary only from one instrument to another in transmitter power, coil size, intercoil separation and transmitter frequency.5.3.2 Some instruments are designed with a rigid, fixed intercoil separation usually less than about 4 meters and are used for relatively shallow measurements of less than 6 meters.5.3.3 For deeper measurements of up to 100 meters, depending on the instrument, the instrument consists of separate coils interconnected by cable, (Fig. 5) and generally operates at several intercoil spacings. Instruments using the “low induction number approximation” usually have a single frequency for each intercoil spacing and are generally referred to as Ground Conductivity Meters (GCMs). Measurements of apparent conductivity, σa, are calculated and displayed in millisiemens per meter (mS/m).5.3.4 FDEM instruments taking multiple frequency measurements at a fixed intercoil separation usually give their results as a ratio of the secondary to primary magnetic fields (Hs/Hp). These instruments usually have some frequencies that satisfy the low induction number approximation from which the apparent conductivity is calculated. The larger multiple coil separation, multiple frequency instruments are mainly used for mineral exploration, whereas the smaller multiple frequency instruments are used for much the same applications as the GCMs.5.4 Limitations and Interferences: 5.4.1 General Limitations Inherent to Geophysical Methods: 5.4.1.1 A fundamental limitation inherent to all geophysical methods lies in the fact that a given set of data cannot be associated with a unique set of subsurface conditions. In most situations, surface geophysical measurements alone cannot resolve all ambiguities, and some additional information, such as borehole data, is required. Because of this inherent limitation in geophysical methods, a frequency domain or ground conductivity survey alone can never be considered a complete assessment of subsurface conditions. It should be noted that multiple methods of measuring electrical conductivity in the earth (that is, FDEM, TDEM, DC Resistivity) will only produce the same answers for the ideal conditions of a nonmagnetic, frequency-independent, isotropic homogeneous half-space. The presence of heterogeneities (for example, layering, objects), anisotropy, magnetic materials, and frequency dependent mechanisms will result in varying geometric patterns of electrical current flow in the ground and consequent different values of measured apparent conductivity between the methods. Properly integrated with other information, conductivity surveying can be an effective method of obtaining subsurface information.5.4.1.2 In addition, all surface geophysical methods are inherently limited by decreasing resolution with depth.5.4.2 Limitations Specific to the FDEM Method: 5.4.2.1 The interpretation of subsurface conditions from frequency domain measurements assumes a nonmagnetic homogeneous horizontally layered earth. Any variation from this ideal results in variations in the interpretation from the actual subsurface. There are areas with soils that contain significant quantities of ferromagnetic or superparamagnetic minerals or metal fragments in which this assumption is no longer valid. This can be tested with electromagnetic instruments (see 5.2.2). If the assumption is incorrect, then the apparent conductivity will be higher than it should be.5.4.2.2 Ground conductivity meters (GCMs) using a single frequency and one intercoil spacing are limited to detecting lateral variations. With two coil orientations, (horizontal and vertical dipole modes), a qualitative interpretation of whether the conductivity is increasing or decreasing with depth is available. Information as to the layering or vertical distribution of the subsurface conductivity can be derived from measurements at different heights above the surface.5.4.2.3 For soundings, using both coil orientations and multiple intercoil separations, only two or three layers can be reasonably interpreted. There must still be a significant conductivity contrast between layers and layer thicknesses.5.4.2.4 Equivalence problems occur when more than one layered model fits the data because combinations of layer conductivities and thicknesses produce the same sounding responses. For example, a thin highly conductive layer will look much like a thicker, less conductive layer of approximately the same conductivity thickness product. These problems are sometimes resolved by using borehole conductivity or resistivity data, knowing the general geology of the area, or by knowing what is being looked for and what response is expected. FDEM systems give the best results when searching for a conductive layer in a resistive medium. It is difficult to resolve resistive thin layers in a conductive medium even if the layers have a significant electrical contrast.5.4.2.5 Frequency domain instruments are best used under relatively high electrical conductivity conditions (greater than 1 mS/m). For low conductivity materials (less than 1 mS/m), useful measurements are better obtained with resistivity methods (Guide D6431).5.4.2.6 Ground conductivity meters (GCMs) have a straight-line (linear) relationship between the true bulk conductivity of a homogeneous half space and the apparent conductivity read by the instrument, provided that the true conductivity is within the region controlled by the low induction number approximation for the physical parameters of the particular instrument-intercoil separation and frequency. As the conductivity of the half space increases, making the approximation less and less valid, the apparent conductivity measured by the GCM or calculated using the low induction number approximation (5.1.4) deviates more and more from the true ground conductivity. Fig. 7 shows this nonlinearity for a short one-meter (3.3 ft) intercoil spaced instrument operating at 13 kHz, and shows that, for this spacing, nonlinearity of response is not a problem for most earth materials.FIG. 7 Non-linearity for a Short-spaced Instrument5.4.2.7 The deviation from linearity, however, can be quite significant for instruments with large intercoil spacings (upwards of 20 m) and relatively high frequency of operation. Here the nonlinearity can start at relatively low values of conductivity and can result in negative values at high values of the true conductivity (Fig. 8).FIG. 8 Non-linearity for a Long-spaced Instrument5.4.3 Natural and Cultural Sources of Noise (Interferences): 5.4.3.1 Sources of noise referred to here do not include those of a physical nature such as difficult terrain or man-made obstructions but rather those of a geologic, ambient, or cultural nature that adversely affect the measurements and hence the interpretation.5.4.3.2 The project's objectives in many cases determine what is characterized as noise. If the survey is attempting to characterize geologic conditions, responses due to buried pipelines and man-made objects are considered noise. However, if the survey were attempting to locate such objects, variations in the measurements due to varying geologic conditions would be considered noise. In general, noise is any variation in the measured values not attributable to the object of the survey.5.4.3.3 Natural Sources of Noise—The major natural source of noise in FDEM measurements is naturally occurring atmospheric electricity (spherics). This interference is caused by solar activity or electrical storms. Information about solar activity can be obtained on the Internet at the National Oceanic and Atmospheric Administration web site (http://www.noaa.gov). Electrical storms many miles away can still cause large variations in measurements. When these conditions exist, it is best to abandon the survey until a better time. Increasing the transmitter power can significantly reduce the effect of spherics. This increases the secondary field strength and hence the signal to noise ratio. Unfortunately such a process is at the expense of a larger and heavier transmitter coil.5.4.3.4 Cultural Sources of Noise—Cultural sources of noise include interference from electrical power lines, communications equipment, nearby buildings, metal fences, surface or near surface metal, pipes, underground storage tanks, landfills and conductive leachates. Interference from power lines is directly proportional to the intercoil spacing and mainly only affects large intercoil spacings (greater than 15 or 20 m). Frequency domain instruments with small intercoil spacings are generally unaffected.5.4.3.5 Surveys should not be made in close proximity to buildings, metal fences or buried metal pipelines that can be detected by frequency domain, unless detection of the buried pipeline, for example, is the object of the survey. It is sometimes difficult to predict the appropriate distance from potential noise sources. Measurements made on-site can quickly identify the magnitude of the problem and the survey design should incorporate this information (see 6.3.2.2).5.4.4 Alternate Methods—In some instances, the preceding factors may prevent the effective use of the FDEM method. Other surface geophysical (see Guide D6429) or non-geophysical methods may be required to investigate the subsurface conditions. Alternate methods, such as DC Resistivity (Guide D6431) or TDEM, which may not be affected by the specific source of interference affecting the frequency domain method may be used to show an electrical contrast.1.1 Purpose and Application: 1.1.1 This guide summarizes the equipment, field procedures, and interpretation methods for the assessment of subsurface conditions using the frequency domain electromagnetic (FDEM) method.1.1.2 FDEM measurements as described in this standard guide are applicable to mapping subsurface conditions for geologic, geotechnical, hydrologic, environmental, agricultural, archaeological and forensic site characterizations as well as mineral exploration.1.1.3 The FDEM method is sometimes used to map such diverse geologic conditions as depth to bedrock, fractures and fault zones, voids and sinkholes, soil and rock properties, and saline intrusion as well as man-induced environmental conditions including buried drums, underground storage tanks (USTs), landfill boundaries and conductive groundwater contamination.1.1.4 The FDEM method utilizes the secondary magnetic field induced in the earth by a time-varying primary magnetic field to explore the subsurface. It measures the amplitude and phase of the induced field at various frequencies. FDEM instruments typically measure two components of the secondary magnetic field: a component in-phase with the primary field and a component 90° out-of-phase (quadrature component) with the primary field (Kearey and Brook 1991). Generally, the in-phase response is more sensitive to metallic items (either above or below the ground surface) while the quadrature response is more sensitive to geologic variations in the subsurface. However, both components are, to some degree, affected by both metallic and geologic features. FDEM measurements therefore are dependent on the electrical properties of the subsurface soil and rock or buried man-made objects as well as the orientation of any subsurface geological features or man-made objects. In many cases, the FDEM measurements can be used to identify the subsurface structure or object. This method is used only when it is expected that the subsurface soil or rock, man-made materials or geologic structure can be characterized by differences in electrical conductivity.1.1.5 The FDEM method may be used instead of the Direct Current Resistivity method (Guide D6431) when surface soils are excessively insulating (for example, dry or frozen) or a layer of asphalt or plastic or other logistical constraints prevent electrode to soil contact.1.2 Limitations: 1.2.1 This standard guide provides an overview of the FDEM method using coplanar coils at or near ground level and has been referred to by other names including Slingram, HLEM (horizontal loop electromagnetic) and Ground Conductivity methods. This guide does not address the details of the electromagnetic theory, field procedures or interpretation of the data. References are included that cover these aspects in greater detail and are considered an essential part of this guide (Grant and West, 1965; Wait, 1982; Kearey and Brook, 1991; Milsom, 1996; Ward, 1990). It is recommended that the user of the FDEM method review the relevant material pertaining to their particular application. ASTM standards that should also be consulted include Guide D420, Terminology D653, Guide D5730, Guide D5753, Practice D6235, Guide D6429, and Guide D6431.1.2.2 This guide is limited to frequency domain instruments using a coplanar orientation of the transmitting and receiving coils in either the horizontal dipole (HD) mode with coils vertical, or the vertical dipole (VD) mode with coils horizontal (Fig. 2). It does not include coaxial or asymmetrical coil orientations, which are sometimes used for special applications (Grant and West 1965).FIG. 1 Principles of Electromagnetic Induction in Ground Conductivity Measurements (Sheriff, 1989)FIG. 2 Relative Response of Horizontal and Vertical Dipole Coil Orientations (McNeill, 1980)1.2.3 This guide is limited to the use of frequency domain instruments in which the ratio of the induced secondary magnetic field to the primary magnetic field is directly proportional to the ground's bulk or apparent conductivity (see 5.1.4). Instruments that give a direct measurement of the apparent ground conductivity are commonly referred to as Ground Conductivity Meters (GCMs) that are designed to operate within the “low induction number approximation.” Multi-frequency instruments operating within and outside the low induction number approximation provide the ratio of the secondary to primary magnetic field, which can be used to calculate the ground conductivity.1.2.4 The FDEM (inductive) method has been adapted for a number of special uses within a borehole, on water, or airborne. Discussions of these adaptations or methods are not included in this guide.1.2.5 The approaches suggested in this guide for the frequency domain method are the most commonly used, widely accepted and proven; however other lesser-known or specialized techniques may be substituted if technically sound and documented.1.2.6 Technical limitations and cultural interferences that restrict or limit the use of the frequency domain method are discussed in section 5.4.1.2.7 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education, experience, and professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged without consideration of a project's many unique aspects. The word standard in the title of this document means that the document has been approved through the ASTM consensus process.1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.1.4 Precautions: 1.4.1 If the method is used at sites with hazardous materials, operations, or equipment, it is the responsibility of the user of this guide to establish appropriate safety and health practices and to determine the applicability of regulations prior to use.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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