## 3 Water Transport Systems of Mining Industry: Evaluating Advanced Inspection Technologies  
### Characterizing Water Transport Systems  
The case study investigates the mining industry's water supply systems primarily source water from nearby mountain ranges and, to a lesser extent, the recovery of industrial wastewater from tailings ponds. These water sources are transported through various aqueducts constructed primarily from carbon steel (API 5L), which is commonly used for oil, gas, and liquid transportation such as steam, water, or slurry. Although some pipeline segments have been replaced over the years, the primary material has remained carbon steel with a thickness categorized as STD to align with industry standards. The five main aqueducts, namely Colaniqui, Inacatac, Salamari, Santaruna, and Tocontai, have varying lengths, diameters, and flow rates, reflective of each aqueduct's unique requirements. * Colaniqui Aqueduct: Transports 50 L/s over 104 km with an elevation drop of 1350 m from the high Andes to mining site. This system has been operational since 1978 with an initial diameter of 16 inches, reducing to 12.7 inches toward the final section. Thickness ranges from 6.35 mm to 4.78 mm. * Inacatac Aqueduct: Primarily supplies drinking water to the mining plant, carrying 155 L/s over 114 km from an elevation of 4041 m. Operational since 1956, the pipeline begins with a 20-inch diameter, reducing to 12 inches with thicknesses ranging from 7.92 mm to 6.35 mm. * Salamari Aqueduct: This 73 km long system transports 470 L/s to mining facilities and features reinforced sections. Pipeline diameters vary between 22.0 and 35.8 inches, with thicknesses between 6.35 and 7.94 mm, indicative of the high-pressure requirements along its route. * Santaruna Aqueduct: With the largest flow rate, the Santaruna aqueduct carries 950 L/s over 64 km. It has diameters ranging from 30.0 to 50.8 inches and thicknesses between 8.89 and 11.11 mm, meeting the heavy-duty needs of mining operations. * Tocontai Aqueduct: The oldest, operating since 1919, this aqueduct spans 91 km, transporting 50 L/s with diameters ranging from 10.0 to 14.0 inches and thicknesses between 4.78 and 6.35 mm. In the mining industry, water transportation pipelines and aqueducts face various environmental and operational challenges that can lead to different types of defects and corrosion mechanisms. The analysis of corrosion potential in water transport pipelines is focused on the internal and external mechanisms affecting five key aqueducts, namely Tocontai, Inacatac, Santaruna, Colaniqui, and Salamari. The assessment incorporates water chemistry indices (Langelier and Ryznar) and external soil aggressiveness parameters, identifying the main factors influencing the durability of steel pipes in these systems. Internal Analysis of Water Corrosion and Scaling Using LSI and RSI Indices:  
The Langelier Saturation Index (LSI) and Ryznar Stability Index (RSI) were applied to evaluate the corrosive or scaling tendencies of the water transported through the aqueducts. The LSI provides a measure of water's chemical balance, while the RSI incorporates empirical data to better estimate corrosion rates and film formation tendencies. The following insights emerged from the analysis. The Tocontai aqueduct exhibited an LSI average of \(-0.7\) (corrosive) and an RSI average of 9.3 (highly corrosive), with no formation of protective carbonate layers and pH values(7.4-8.6), indicating localized corrosion risks due to oxidizing agents and passive layer deterioration. The Inacatac aqueduct showed an LSI average of 0.2 (neutral to slightly scaling) and an RSI average of 7.7 (corrosive), where high dissolved oxygen levels and pH variability (7.4-8.7) promoted corrosion despite neutral LSI. In the Santaruna aqueduct, an LSI average of 1.0 (slightly scaling) and an RSI average of 6.3 (near equilibrium) indicated minimal carbonate formation, though localized corrosion remained a concern, particularly with fluctuating pH levels (7.5-8.6).