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radar, rebar scanning). Cored concrete samples will be sent to a laboratory for compressive strength testing. Corrosion visual inspection and testing will be performed by subconsultant RF Yeager (concrete rebound/sounding test per "ASTM D4580", isolated half -cell potential testing per "ASTM C876", pH concrete testing). Subconsultant DN Tanks will assist the inspection of the two prestressed circular concrete reservoirs at the John Garthe site. Exposing of the existing prestressing may be required if the existing wall shows signs of possible distress. Task 4: Engineering Services Structural Analysis Following the review of available City records and the completion of all necessary field investigation, inspection and testing activities, Tetra Tech will perform a structural and seismic analysis of each reservoir. The analysis will identify deficiencies of each structure. Our structural analysis will be performed in accordance with the ACI 350.3-06 standard, "Seismic Design of Liquid -Containing Concrete Structures" and utilize prescriptive geotechnical design parameters. Each component of each reservoir's lateral force resisting system will be analyzed to determine its state of stress when subjected to the loading (demand) required by current design standards using our own proprietary software developed in- house for analyzing conventional and prestressed concrete reservoirs. These values will be divided by the component strength dictated by the same standards (capacity), resulting in the calculated demand/capacity (D/C) ratio for the component. The D/C ratio is a measurement of the structural adequacy of a member when loaded. To easily digest the results of our structural analysis, a demand/capacity matrix will be prepared showing the D/C ratios for each structural component analyzed, for each reservoir, all in one table for side -by -side comparison. An example is provided in Table T-1 on the next page. To help facilitate the interpretation of the D/C matrix, a similar table will be produced showing a color -coded priority (in terms of public safety) assigned for each reservoir structural component analyzed, for each reservoir, also in one table for side -by -side comparison. An example is provided in Table T-2 on the next page. Comprehensive Engineerina Report Following the completion of the structural and seismic analysis, Tetra Tech will prepare a comprehensive engineering report and submit the report to the City for review. The report will include: • An executive summary • Detailed discussion of all records reviewed and all inspections, investigations and testing activities performed for each reservoir • Detailed discussion of findings generated during the field investigation and testing phase documenting the existing condition of each reservoir and the surrounding site • Comprehensive evaluation of the structural & seismic integrity of each reservoir as it relates to applicable standards and codes with a detailed discussion of the results with calculations attached for reference • A discussion summarizing findings of the circular prestressed reservoir specialist subconsultant (Ninyo & Moore), who will perform the inspection for the two John Garthe prestressed circular reservoirs; the results from all field testing will be included in the report appendix • A discussion summarizing findings of the material testing subconsultant (Ninyo & Moore) who will perform the material testing; the results from all field testing will be included in the report appendix • A matrix that quantifies the demand -to -capacity (D/C) ratios for the elements of each reservoir that were check as part of the structural/seismic analysis. • Evaluations of corrosion -observed concrete structure, piping and appurtenances, and evaluations of the concrete deterioration that was observed. • A discussion summarizing findings of the corrosion engineering subconsultant (RF Yeager) who will perform the corrosion testing; the results from all field testing will be included in the report appendix CITY OF SANTA ANA 7 TETRA TECH