Bilangan 19:8

19:8 The one who burns it ¹  must wash his clothes in water and bathe himself in water. He will be ceremonially unclean until evening.

Bilangan 19:10

19:10 The one who gathers the ashes of the heifer must wash his clothes and be ceremonially unclean until evening. This will be a permanent ordinance both for the Israelites and the resident foreigner who lives among them.

[19:8]  ¹ sn Here the text makes clear that he had at least one assistant.