Cal. Pub. Res. Code § 19522

If a manufacturer of fiberglass is unable to obtain sufficient amounts of cullet within any certification period, the manufacturer shall certify this fact to the department and provide the department with the specific reason for failing to use cullet, including verification of a best faith effort to use the cullet, and evidence that the cullet failed to meet minimum quality specifications pursuant to Chapter 3 (commencing with Section 19515) and, therefore, presented a significant barrier to meeting the requirements of Chapter 2 (commencing with Section 19510).