The children were discovered by Nicole Elton, a neighbor of the mother, as she arrived at the Boulders Apartments Complex, 750 S. 650 West, on the morning of Sept. 25, 2012.
The girl said she was in the dumpster looking for food for the family, according to Elton. She pulled the toddler from the bin and since the girl was clad only in pants and the boy only a diaper, Elton clothed them and took them to the apartment complex office since their mother wouldn't answer her door.
Provo police were called but could not contact the mother either by knocking on her apartment door or calling her cellphone, said Sgt. Brandon Post.
They also tried to find the father, but discovered he was in the Utah County Jail, Post said.
Police then learned Chavez had two other children, both 8-month-old infants, inside her apartment.
After obtaining a key from apartment management, officers found a very unkempt apartment littered with dirty diapers and empty beer cans, Post said.
The Division of Child and Family Services responded and took custody of all four children.
Chavez was later booked into the Utah County Jail on suspicion of child abuse and/or neglect. She was formally charged by prosecutors on Oct. 3.