Cal. Health & Safety Code § 25116.5

(a) “Intermediate manufacturing process stream” means a material, or combination of materials, that meets all of the following conditions:
1. (1) It is produced as part of the manufacturing process.
2. (2) It is used onsite on a batch or continuous basis, in either the same or in a different manufacturing process to produce a commercial product.
3. (3) It is not a recyclable material.
4. (4) The person who produced the material or combination of materials is able to demonstrate all of the following:
  1. (A) The material, or combination of materials, is used, alone or in combination with other materials, in a manufacturing process that is designed for its use.
  2. (B) The material, or combination of materials, is not accumulated or stored in amounts greater than can be used in the manufacturing process.
  3. (C) The material, or combination of materials, is not handled, stored, or processed in a manner that is inconsistent with its intended use or the operating requirements of the manufacturing process.
  4. (D) The material, or combination of materials, is not burned or incinerated for the purpose of abandoning or relinquishing the material or combination of materials, except as may otherwise be allowed under both this chapter and the federal act.
(b) Notwithstanding subdivision (a), a material is not an intermediate manufacturing process stream if it has been released in violation of this chapter, or any other applicable law, or an order issued pursuant to this chapter or other applicable law, unless it has been released into an appropriate containment area or structure and has been promptly recovered and returned to the manufacturing process, without prior treatment, for use in the originally intended manufacturing process.