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ATKiNS <br />Task 02 Survey of Oxidation Ditch and Bridges. <br />Oral history and initial visual observations suggest that there is significant <br />movement of the walls of the basin. A survey will be performed to determine the <br />extent of the any movement in the walls and/or bridges. The results of the survey <br />will be used in Task 03 as part of the structural evaluation. <br />a. Survey Set -Up and Implementation <br />The survey will begin with the establishment of 72 Monitoring Targets on 27 <br />different locations around the tank's outside walls and crossing bridges to obtain <br />horizontal and vertical positions. The Monitoring Targets will be established at <br />bottom, middle, top of walls and along the 3 (three) crossing bridges on the top <br />of the tank. The Monitoring Targets will be located 3 (three) times: full, empty, <br />then full again. <br />b. High -Resolution Scan <br />The storage tank will be scanned utilizing a High -Resolution Laser Scanner to <br />generate a 3-D model to capture existing the tank's features for use in evaluating <br />any movement and in facilitating the design of any recommended structural <br />repairs. The scan will be conducted through the utilization of a combination of <br />robotic total stations, first -order digital level with a bar-coded INVAR rod, Fixed <br />Scanning Technology and RTK GPS. <br />c. Survey Details <br />A list of specific tasks and location of the Monitoring Targets associated with this <br />survey are included in Exhibit B. The survey is anticipated to take up to 10 working <br />days. <br />Task 03 Structural Component Evaluation and Data Collection <br />a. Staff Interviews <br />The objective of the staff interviews is to determine what the goals and objectives <br />are for this structure. Discussions will include a review of the structure's historic <br />and current function, IRC's risk tolerance, future use(s), and long-term anticipated <br />design life. <br />b. Review of Existing Records <br />Consultant will prepare a data request to obtain and review readily available <br />information including as -built drawings of the ditches and history of any <br />maintenance or upgrades associated with the structural components of the <br />ditches, calculations, or past reports prepared for these structures. <br />c. Structural Inspection and Evaluation <br />Consultant will visit site to perform a non-destructive structural evaluation of <br />oxidation ditch structure and associated bridge structures. The goal for inspection <br />is to visually observe and document condition of the structures and record any <br />defects observed during inspection. Photographs will be taken of defects <br />observed during inspection for areas that can be safely accessed during time of <br />inspection. The record of defects will be used as a baseline for comparison in the <br />114 <br />