Blue Mud and Human Sacrifice

Here's another detail for your file of gruesome facts about the Maya, from an article about their famous blue paint:

Among the more remarkable discoveries of the paint in context was a 14-foot thick (4 meters) layer of blue mud at the bottom of a naturally formed sinkhole, called the Sacred Cenote, at the famous Pre-Columbian Maya site Chichén Itzá in the Yucatán Peninsula of Mexico. When the Sacred Cenote was first dredged in 1904, it puzzled researchers, but some scientists now believe it was probably left over from blue-coated human sacrifices thrown into the well as part of a Maya ritual.

The Sacred Cenote is about 200 feet (60 m) in diameter, so a 14-foot thick layer would be 440,000 cubic feet, or 12,000 cubic meters.  How many bodies do you suppose it would take to color that much clay blue?