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Application for Encroachment Permit <br /> County of San Joaquin,California <br /> Sheet 2 <br /> The State of California's Department of Water Resources (DWR) is undertaking a <br /> geotechnical evaluation of aging and deteriorating levees in the Sacramento and San <br /> Joaquin River Valleys and Delta. Please see attached fact sheets of the levee evaluation <br /> program and the geophysical electromagnetic survey, the subject of this application. <br /> As a part of the unprecedented efforts, a number of proven methods and innovative <br /> technologies are being used to assess the levees' structural integrity and identify which <br /> areas are most in need of improvements or repairs. This application involves the <br /> geophysical electromagnetic survey. <br /> Geophysical electromagnetic (EM) surveys are one of the unique tools that will be used <br /> to evaluate levee subsurface conditions. The proposed type of geophysical <br /> electromagnetic surveys involves a low-level helicopter passes over selected levees; this <br /> is referred to helicopter-borne multi-frequency electromagnetic (HEM) survey or <br /> airborne electromagnetic survey. A survey "bird," which resembles an airborne torpedo <br /> (see attached fact sheets), is suspended from the helicopter about 100 feet above the <br /> levees. As the helicopter flies parallel to the levees, the EM technology senses variations <br /> in the ground's electrical conductivity to depths of more than 100 feet underground. The <br /> goal is to map important changes in soil types and ground conditions, identifying zones <br /> where permeable soils are present or excessive water penetration is taking place. <br /> Pursuant to FAA regulations and safety of non-participating public, the helicopter pilot <br /> needs to maintain a buffer zone of 200 feet wide along the flight path of the survey <br /> "bird." Along the segment of roadways within this buffer zone of the HEM routes listed <br /> below, we are requesting closure during the survey. The helicopter will be traveling <br /> about 30 miles per hour(mph) during the survey; therefore, we anticipate closure of these <br /> of segments of roadways to be about 2 to 4 hours. <br /> Map Sheet see attached Roadway <br /> S-13 Brookside Road <br /> S-16 March Lane <br /> S-16 E4@Qk4&W&44ead p 0 A <br /> S-21 Cardinal Avenue <br />