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Task 2-Surveying <br /> Surveying and mapping will include detailed topographic mapping of the dam site and eastern reservoir rim, <br /> establishment of construction benchmarks,and an underwater inspection of portions of the project. Base <br /> maps of as-built conditions of the tunnel and spillway structures will be prepared in order to prepare accurate <br /> design plans. A boundary survey will be completed and used to develop a legal description of the property <br /> needed for the outlet discharge structure. <br /> The topographic survey will be subcontracted and accomplished using LiDAR mapping techniques. <br /> Topographic maps of the dam and appurtenant structures with one-foot contours will be prepared. LiDAR <br /> mapping of the ancient block slide and eastern one-third of the reservoir rim covering over 1.7 square miles <br /> will also be performed in order to evaluate and monitor reservoir rim stability. Mapping resulting from the <br /> LiDAR survey will use state plane coordinates and the NAVD88 vertical datum. Four benchmarks will be <br /> established during this task that will serve and control points for construction staking. The benchmarks will <br /> be located to be near the work,but outside the anticipated construction zone. Structure surveys of as-built <br /> dimensions of the tunnel and spillway will be made in the field. <br /> A remote operated vehicle(ROV)will be used to perform an underwater survey of the upstream tunnel portal <br /> and underwater portion of the rock slide at the left abutment. The objective of this survey is to determine the <br /> condition of the cofferdam and gates at the upstream tunnel portal and to gain an understanding of the size <br /> and distribution of materials at the submerged portion of the rock slide that will <br /> be covered by the clay blanket. The ROV survey will be recorded on audio and video,and made available to <br /> the design team and construction contractors during the bidding period. <br /> Deliverables: Topographic Survey, Construction Benchmarks,Boundary Survey, Structure Surveys,and <br /> ROV Survey <br /> Task 3-Geotechnical Exploration <br /> This task includes the field work required to acquire the geotechnical data for design of the rehabilitation. <br /> Comprehensive geotechnical studies of the site were conducted by Chen&Associates(1983)for the 1983 <br /> construction improvements. This work includes drilling of 12 borings, installation of six piezometers and <br /> two inclinometers,and laboratory testing of soil and rock. Currently,there are four functioning piezometers <br /> that are monitored on a regular basis. Only one inclinometer remains on-site and no historical baseline data <br /> appears available for this instrument. <br /> Comprehensive geologic mapping of the reservoir was conducted in 2007 by Robert Kirkham and D&A as <br /> part of the CDM(2008)study. Additional studies of reservoir rim stability were recommended by Mr. <br /> Kirkham. Additional geologic mapping of the block slides on the northeast part of the reservoir will be <br /> performed under this contract,as well as perform LiDAR surveying(as described above)and install <br /> instrumentation at the base of the slide. <br /> A total of four rotary borings(three core and one ODEX),nine auger borings,and 12 test pits are proposed. <br /> The investigation plan is summarized in the table below: <br /> - 3 - <br />