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Equipment Report Equipment. Operations and Limitations Corporate Location 750 Patrick's Place Office # 888-858-9830 Brownsburg, IN 46112 Fax # 888-858-9829 hiW://www.BHUG.com Equipment Description — Blood Hound uses a variety of equipment to identify and locate subsurface structures, such as direct connect and inductive utility location transmitters and receivers with multi -frequency broadcasts and reception capabilities, ground penetrating radar, sewer cameras (both robotic and fiber 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 structures. Traditional EM equipment is used as the primary tool to determine the location of all conductive subsurface structures, as well as any utilities that have locating wires (i.e. gas lines) buried with the non-conductive utility to facilitate location. This equipment operates using frequencies ranging 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, estimated depth of the target utility, and distance for. which the target utility must be marked. Frequencies are often changed during operations to improve the quality of the signal, decrease interference, and/or increase the range for the transmitted signal. 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 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 frequency. By measuring peak or null signal measurements, the lateral line location can be determined. Blood Hound uses a variety of Ground Penetrating Radar (GPR) units from multiple manufacturers. Blood Hound employs antenna frequencies 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- processing analysis, including the development of subsurface response maps. The most commonly used antennae operate in a frequency range of 250 to 350 MHz„ which provides the greatest balance of resolution and effective depth penetration. Frequency ranges higher than this provide greater resolution and better penetration through more conductive or signal absorbing materials (i.e. clay soils, concrete, etc). However, this increased resolution comes at the cost of significantly reduced depth penetration. GPR operates by radiating a radio band frequency into the soil from the transmitter contained within the antenna assembly. This signal is reflected to 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. 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 is then projected by making assumptions regarding the transmission rate of the signal through the medium. If the signal velocity assumptions are not accurate, then the depth estimates will not be accurate. Blood Hound also performs Electromagnetic soil conductivity analysis (EM Induction Survey). This method uses a Fisher TW -6 "Split Box" locator mounted on an inductive sweep bar. The bar places the transmitter and receiver four feet apart, with the inductive transmitted field oriented in an opposing orientation from the receiving antenna. This opposing orientation allows for the receiver to not register the presence of the transmitting 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 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 magnetometers. Factors Effecting Performance. of Equipment — There are several factors that can impact the effectiveness of the EM Locating equipment: • Target Utility Composition — EM locating is only effective if the target utility is composed of continuous conductive material. Plastic, concrete, clay, or other non-conductive materials cannot be located using EM locating techniques. In addition, some metals are not highly conductive, which makes locating 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. Additionally, many pipes are composed of individual sections which maybe gasketed . This can impede the current at each pipe joint. • 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 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 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 on an unshielded line, the more degraded the signal will be. • Conductive Pathway to Ground — Locating is accomplished by creating a complete circuit, and the transmitted signal must be able to return to the ground 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. Thus, the signal may not travel along the desired pathway. Additionally, soil conditions can affect the pathway to ground. For example, in highly conductive soils, a signal can inductively find a pathway to ground even in an open circuit. • 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 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 surface. Similarly, shielding between the target utility and the receiver can affect the signal reception and create a loss of signal. Utility Locating — Ground Radar — Vacuum Excavation — Sewer Camera — GPS/GIS Mapping 40