2 Chronicles 29:3, 16

In the first month of the first year of his reign, he opened the doors of the House of ADONAI and repaired them.

So the kohanim went into the inner part of the House of ADONAI to purify it. They brought out to the courtyard of the House of ADONAI every impure thing that they found in the temple of ADONAI. Then the Levites received it and carried it out to Kidron Valley.