Protecting the Great Walls of Saqsaywaman by Restoring the Original Incan Drainage Infrastucture

The Great Walls of Saqsaywaman, Peru – an ancient Incan archeological site and UNESCO world heritage site – are beginning to show signs of failure after 500 years of remaining structurally sound. Hydrostatic pressure buildup, caused by uncontrolled stormwater runoff, triggered a collapse of one of the walls in 2010. In this thesis, it was hypothesized that restoring the original Incan drainage infrastructure at Saqsaywaman is a potential way to control stormwater runoff in order to protect this cultural icon from further failure. Using field data, investigative engineering analysis, and archeological justification, a possible reconstruction of the original drainage infrastructure was designed. This design consisted of a well-drained terrace system and a surface drainage system of channels and hydraulic drops. Runoff analyses were conducted to validate the efficacy of these possible reconstructions as methods of stormwater control. By implementing the terrace system, it was found that runoff was redirected away from the Great Walls and that surface runoff was reduced by 51% for a hundred-year storm. By implementing the surface drainage system, it was found that most of the remaining 49% of surface runoff from the hundred-year storm was directed out of the site in a controlled manner. In conclusion, the results of the runoff analyses confirm the hypothesis that restoring the site to its original Incan drainage infrastructure is a potential solution to effectively protect the Great Walls from further runoff-induced damage.