Ariz. Admin. Code § R18-13-1003 - Design Criteria

A. 40 CFR 257.70 through 40 CFR 257.74, revised as of December 14, 2020 (and no future editions) are incorporated by reference, modified by the following subsections, and on file with ADEQ.

B. 40 CFR 257.73(a)(4) is amended by deleting "not to exceed a height of 6 inches above the slope of the dike,".

C. 40 CFR 257.73(d)(1)(iv) is amended by deleting "not to exceed a height of 6 inches above the slope of the dike,".

D. 40 CFR 257.74(a)(4) is amended by deleting "not to exceed a height of 6 inches above the slope of the dike,".

E. 40 CFR 257.74(d)(1)(iv) is amended by deleting "not to exceed a height of 6 inches above the slope of the dike,".

F. 40 CFR 257.74(d)(1)(v)(B) is amended as follows: "(B) The combined capacity of all spillways must adequately manage flow during and following the peak discharge from a:

(1) Probable maximum flood (PMF) for a high hazard potential CCR surface impoundment; or

(2) 1000-year flood or 0.5 PMF, whichever is greater for a significant hazard potential CCR surface impoundment; or

(3) 100-year flood or 0.25 PMF, whichever is greater for a low hazard potential CCR surface impoundment."

G. Subsection (F) of this Section is based on Arizona dam safety standards in existence on July 12, 2024, is additional to those in 40 CFR 257, subpart D, as incorporated in this Article, and does not apply to:

1. CCR surface impoundments with a maximum height of less than 6 feet, regardless of storage capacity;

2. CCR surface impoundments with a maximum height of between 6 and 25 feet and a storage capacity of less than 50 acre-feet; or

3. CCR surface impoundments with a maximum height greater than 25 feet and a storage capacity of 15 acre-feet or less.

Notes

Ariz. Admin. Code § R18-13-1003

New section made by final rulemaking at 31 A.A.R. 1363, effective 6/1/2025.