§ 816.84 - Coal mine waste: Impounding structures.

§ 816.84 What special requirements apply to coal Coal mine waste: Impounding structures.

New and existing impounding structures

?(a) Impounding structures

constructed of coal mine waste or intended to impound coal mine waste

must

shall meet the requirements of § 816.81

of this part

.

(

b) You may not use coal mine waste to construct impounding structures unless you demonstrate, and the regulatory authority finds in writing,

a) Coal mine waste shall not be used for construction of impounding structures unless it has been demonstrated to the regulatory authority that the stability of such a structure conforms to the requirements of this part and

that

the use of coal mine waste will not have a detrimental effect on downstream water quality or the environment

as a result of acid drainage or toxic

due to acid seepage through the impounding structure.

You must discuss the

The stability of the structure and the

prevention and

potential impact of acid

drainage or toxic

mine seepage through the impounding structure shall be discussed in detail in the design plan submitted to the regulatory authority in accordance with § 780.25 of this chapter.

(

c

b)

(1)

You must design, construct, and maintain each

Each impounding structure constructed of coal mine waste or intended to impound coal mine waste shall be designed, constructed and maintained in accordance with

paragraphs

§ 816.49 (a) and (c)

of § 816.49 of this part. (2) You may not retain these structures

. Such structures may not be retained permanently as part of the approved postmining land use.

(

3

2) Each impounding structure constructed of coal mine waste or intended to impound coal mine waste that meets the criteria of § 77.216(a) of this title

must

shall have sufficient spillway capacity to safely pass, adequate storage capacity to safely contain, or a combination of storage capacity and spillway capacity to safely control, the probable maximum precipitation of a 6-hour precipitation event, or greater event as specified by the regulatory authority.

(

d) You must design spillways

c) Spillways and outlet works shall be designed to provide adequate protection against erosion and corrosion. Inlets

must

shall be protected against blockage.

(

e) You must direct surface runoff

d) Drainage control. Runoff from areas above the disposal facility

and

or runoff from

the

surface of the facility that may cause instability or erosion of the impounding structure shall be diverted into stabilized diversion channels designed

and constructed

to meet the requirements of § 816.43

of this part

and designed to safely pass the

runoff

round off from a 100-year, 6-hour design precipitation event.

You must use the appropriate regional Natural Resources Conservation Service synthetic storm distribution to determine the peak flow from surface runoff from this event(e) Impounding structures constructed of or impounding coal mine waste shall be designed so that at least 90 percent of the water stored during the design precipitation event can be removed within a 10-day period.

(f) For an impounding structure constructed of or impounding coal mine waste, you must remove at least 90 percent of the water stored during the design precipitation event shall be removed within the 10-day period following the design precipitation event.

[48 FR 44029, Sept. 26, 1983, as amended at 53 FR 43606, Oct. 27, 1988; 81 FR 93392, Dec. 20, 2016; 82 FR 54979, Nov. 17, 2017]