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Equipment Report
<br />Equipment Operations and Limitations
<br />Corporate Location:
<br />750 Patrick's Place Office # 888-858-9830
<br />Brownsburg, IN 46112 Fax # 888-858-9829
<br />ht1P.,11www.HHUQ.eAm
<br />Equipment Description —
<br />Blood Hound uses a variety of equipment to identify and locate subsurface structures, such as direct connect and inductive utility location
<br />transmitters and receivers with multi -frequency broadcasts and reception capabilities, ground penetrating radar, sewer cameras (both robotic and fiber
<br />optic push/pull), and other equipment, to locate the lateral position of buried structures, as well as to provide estimates on the depths of subsurface
<br />structures.
<br />Traditional EM equipment is used as the primary tool to determine the location of all conductive subsurface structures, as well as any utilities that
<br />have locating wires (i.e. gas lines) buried with the non-conductive utility to facilitate location. This equipment operates using frequencies ranging
<br />from 512 Hz up to and including 480 kHz. The frequency that is selected is dependent on the type of utility to be located, operator preference,
<br />estimated depth of the target utility, and distance for which the target utility must be marked. Frequencies are often changed during operations to
<br />improve the quality of the signal, decrease interference, and/or increase the range for the transmitted signal.
<br />EM locating operates by conducting an AC electric current through the target utility at a specific frequency. This causes the target utility to radiate a
<br />radio signal at the desired frequency. This radiated radio signal is then detected using the receiver, which is tuned to detect radio fields at the desired
<br />frequency. By measuring peak or null signal measurements, the lateral line location can be determined.
<br />Blood Hound uses a variety of Ground Penetrating Radar (GPR) units from multiple manufacturers. Blood Hound employs antenna frequencies
<br />ranging from 250 MHz up to 1.6 GHz, depending on the specific needs of the survey. Data can be analyzed in real-time, or collected for post-
<br />processing analysis, including the development of subsurface response maps.
<br />The most commonly used antennae operate in a frequency range of 250 to 350 MHz„ which provides the greatest balance of resolution and effective
<br />depth penetration. Frequency ranges higher than this provide greater resolution and better penetration through more conductive or signal absorbing
<br />materials (i.e. clay soils, concrete, etc). However, this increased resolution comes at the cost of significantly reduced depth penetration.
<br />GPR operates by radiating a radio band frequency into the soil from the transmitter contained within the antenna assembly. This signal is reflected to
<br />the receiver contained in the antenna unit, and this received signal is then converted into visual patterns based on the intensity of the reflected signal.
<br />The depth of the target reflection pattern is determined based on the time elapsed from the transmission until the reception of the reflected signal, and
<br />is then projected by making assumptions regarding the transmission rate of the signal through the medium. If the signal velocity assumptions are not
<br />accurate, then the depth estimates will not be accurate.
<br />Blood Hound also performs Electromagnetic soil conductivity analysis (EM Induction Survey). This method uses a Fisher TW -6 "Split Box" locator
<br />mounted on an inductive sweep bar. The bar places the transmitter and receiver four feet apart, with the inductive transmitted field oriented in an
<br />opposing orientation from the receiving antenna. This opposing orientation allows for the receiver to not register the presence of the transmitting
<br />field. When the transmitting field encounters a conductive object (metal), the field is bent, which results in the detection of the field by the receiving
<br />antenna. This equipment allows for the detection of conductive objects, and is not limited to the detection of ferrous metals as is the case with many
<br />magnetometers.
<br />Factors Effecting Performance of Equipment —
<br />There are several factors that can impact the effectiveness of the EM Locating equipment:
<br />• Target Utility Composition — EM locating is only effective if the target utility is composed of continuous conductive material. Plastic, concrete, clay, or
<br />other non-conductive materials cannot be located using EM locating techniques. In addition, some metals are not highly conductive, which makes locating
<br />using EM techniques difficult. For example, cast iron is a poor conductor and cast iron lines can often be difficult to locate using standard EM techniques.
<br />Additionally, many pipes are composed of individual sections which may be gasketed . This can impede the current at each pipe joint.
<br />• Shielding of Target Utility— Since EM locating uses an electronic signal, unshielded lines that are directly buried in the soil (i.e. water lines) can be difficult
<br />to locate for significant distances. This is due to the continuous loss of transmitted signal directly to the ground. As the signal travels along the utility, a
<br />significant portion of the signal is lost to ground, resulting is decreased signal quality. The greater the distance between the transmitter and the location point
<br />on an unshielded line, the more degraded the signal will be.
<br />• Conductive Pathway to Ground — Locating is accomplished by creating a complete circuit, and the transmitted signal must be able to return to the ground
<br />in some form. An open circuit is generally much more difficult to locate since the circuit is not complete, and the emitted signal cannot return to ground.
<br />Thus, the signal may not travel along the desired pathway. Additionally, soil conditions can affect the pathway to ground. For example, in highly
<br />conductive soils, a signal can inductively find a pathway to ground even in an open circuit.
<br />• Depth — The signal induced onto the target path must have sufficient strength to be detectable at the surface. Utility lines deeper than 15 feet are often
<br />difficult to locate due to the inability of the radio frequency being radiated from the target line to effectively radiate through the soil to the receiver at the
<br />surface. Similarly, shielding between the target utility and the receiver can affect the signal reception and create a loss of signal.
<br />Utility Locating — Ground Radar — Vacuum Excavation — Sewer Camera — GPS/GIS Mapping
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