Listen to the following transcript from an episode of the audio documentary series 'Arqueología Moderna' concerning the preservation of the ancient adobe city of Chan Chan in northern Peru:
'[Host]: Welcome to Arqueología Moderna. Today, we examine the delicate balance between environmental threats and structural conservation at Chan Chan, the largest mud-brick citadel in the Americas. With intense humidity and rising groundwater tables caused by recurring El Niño weather patterns, conservators face unprecedented preservation hurdles. Lead structural engineer Dr. Valeria Morales describes the team's intervention:
[Dr. Morales]: Many initial proposals recommended coating the exterior adobe walls with synthetic acrylic sealants to block surface moisture. However, our field trials proved that external resins trap humidity inside the clay bricks, accelerating internal decay. Similarly, while perimeter windbreak fences successfully reduce surface erosion from salty marine gusts, they do not resolve moisture below ground level. The definitive solution proved to be hydrologic redirection. We excavated a continuous one-point-eight-meter gravel trench beneath the foundation perimeter, lined with a permeable geotextile membrane. This subsurface channel intercepts rising capillary groundwater and diverts it away into an exterior basin before it touches the clay base, successfully stabilizing the structure without altering the historic facade.'
According to the audio report, which specific measure was successfully implemented to resolve the problem of capillary moisture at the foundation of the adobe walls?
- Excavating a subsurface gravel trench lined with a permeable geotextile membraneCevap
- BApplying synthetic acrylic coatings across the outer surfaces of the adobe bricks
- CErecting perimeter windbreak fences to block salt-laden coastal breezes
- DInjecting chemical hardeners directly into the foundation clay layers