2020 Idaho Code
Title 39 - HEALTH AND SAFETY
Chapter 1 - ENVIRONMENTAL QUALITY — HEALTH
Section 39-176E - CONSTRUCTION REQUIREMENTS FOR NEW PHOSPHOGYPSUM STACKS — LATERAL EXPANSIONS OF EXISTING PHOSPHOGYPSUM STACKS.

39-176E. CONSTRUCTION REQUIREMENTS FOR NEW PHOSPHOGYPSUM STACKS — LATERAL EXPANSIONS OF EXISTING PHOSPHOGYPSUM STACKS. Any operator desiring to construct a new phosphogypsum stack, a material component thereof, or a lateral expansion shall submit to the department of environmental quality for review and approval prior to commencing construction a design and construction plan, including construction quality control, that includes minimum design and construction requirements to control and minimize the movement of waste and waste constituents into the environment. Plans and specifications submitted to satisfy the requirements of sections 39-176A through 39-176F, Idaho Code, shall be certified by a registered professional engineer. The minimum design requirements include the following features and standards:

(1) Run-on and runoff controls for the phosphogypsum stack systems for the collection, control, and treatment, as needed, of run-on and runoff from the systems;

(2) Liner and leachate control systems that achieve the following minimum design standards:

(a) Phosphogypsum stacks shall be constructed atop a composite liner or approved alternative of equivalent hydraulic conductivity and durability. Liners shall be constructed of materials that have appropriate physical, chemical, and mechanical properties to prevent failure;

(b) All liner and leachate control system components shall have appropriate quality control and quality assurance standards, specifications, and procedures for construction.

(c) Phosphogypsum stacks shall have a leachate control system. Any leachate emanating from a phosphogypsum stack system shall be routed to a collection pond, such as a decant pond or similar water structure, to be contained within the system or recirculated to the production plant, or, if discharged, treated if required to meet applicable water quality and discharge requirements. Collection ponds shall be constructed with a composite liner or an approved alternative of equivalent hydraulic conductivity and durability;

(d) Auxiliary holding ponds shall be designed with a synthetic liner or an approved alternative of equivalent hydraulic conductivity and durability; and

(e) Process wastewater conveyances shall be constructed with a liner or pipe.

(3) Perimeter dikes that shall incorporate minimum design standards for freeboard, safety, and slope stability design factors, construction methods, and other related parameters. Appropriate quality control and quality assurance standards, specifications, and procedures for perimeter dike construction shall be implemented;

(4) Any lateral expansion must be constructed in accordance with the same requirements as a new phosphogypsum stack. Except for incidental deposits of phosphogypsum entrained in the process wastewater, or conditioned phosphogypsum used as a cushion layer against rock slope, placement of phosphogypsum outside the phosphogypsum stack footprint is considered a lateral expansion; and

(5) A groundwater monitoring plan.

History:

[39-176E, added 2020, ch. 51, sec. 5, p. 121.]