# Title 69 — Public Service Commission

## Article 69-05.2 — Surface Coal Mining and Reclamation Operations

## Chapter 69-05.2-20 — Performance Standards - Dams and Embankments Constructed of or Impounding Coal Processing Waste

Coal Processing Waste - General Requirements
Coal Processing Waste - Site Preparation
Coal Processing Waste - Design and Construction
### § 69-05.2-20-01. Performance standards - Dams and embankments constructed of or

impounding coal processing waste - General requirements.
Dams and embankments constructed of or impounding coal processing waste as a temporary
disposal method must comply with this chapter and permanent disposal of the waste must comply with
section 69-05.2-19-02. Waste may not be used to construct the dams and embankments unless it has
been demonstrated to the commission that the stability of the structure conforms to the requirements of
subsection 1 of section 69-05.2-20-03. It must also be demonstrated that the use of waste material will
not have a detrimental effect on downstream water quality or the environment due to toxic seepage
through the dam or embankment. All demonstrations must be approved by the commission. Prior to
commission approval, the state engineer will have an opportunity to review the plans and design of the
structures.
History: Effective August 1, 1980; amended effective May 1, 1990.
General Authority: NDCC 38-14.1-03
Law Implemented: NDCC 38-14.1-24, 38-14.1-25
### § 69-05.2-20-02. Performance standards - Dams and embankments constructed of or

impounding coal processing waste - Site preparation.
Before coal processing waste is placed at a dam or embankment site:
1. All vegetative material must be cleared from the site, and suitable plant growth material
removed and stockpiled according to this article; and
2. Surface drainage that may cause erosion to the embankment area or the embankment
features, whether during construction or after completion, must be diverted by diversion
ditches that comply with the requirements of section 69-05.2-16-06. Adequate outlets for
discharge from these diversions must comply with section 69-05.2-16-10. Diversions to carry
drainage from the upstream area away from the impoundment area and runoff from the
surface of the impoundment facility must be designed to carry the peak runoff from a one
hundred-year, six-hour precipitation event. The diversion must be maintained to prevent
blockage, and the discharge must comply with section 69-05.2-16-10. Sediment control
measures must be provided at the discharge of each diversion ditch before entry into natural
watercourses according to chapter 69-05.2-16.
History: Effective August 1, 1980; amended effective May 1, 1990.
General Authority: NDCC 38-14.1-03
Law Implemented: NDCC 38-14.1-24, 38-14.1-25

### § 69-05.2-20-03. Performance standards - Dams and embankments constructed of or

impounding coal processing waste - Design and construction.
1. The design of each dam and embankment constructed of coal processing waste or intended
to impound the waste must comply with subsections 9 through 21 of section 69-05.2-16-09,
modified as follows:
a. The design freeboard between the lowest point on the embankment crest and the
maximum water elevation must be at least three feet [91.44 centimeters].
b. The dam and embankment must have a minimum safety factor of 1.5 for a normal pool
with steady seepage saturation conditions, and the seismic safety factor must be at least
1.2.
c. The dam or embankment foundation and abutments must be designed to be stable under
all conditions of construction and operation of the impoundment. Sufficient foundation
investigations and laboratory testing must be performed to determine the safety factors of
the dam or embankment for all loading conditions appearing in subdivision b and for all
increments of construction.
d. Each structure that meets the criteria of 30 CFR 77.216(a) must have sufficient spillway
capacity to safely pass the probable maximum precipitation of a six-hour precipitation
event, or greater event specified by the commission, when the impoundment is at high
water elevation.
2. Spillways and outlet works must be designed to provide adequate protection against erosion
and corrosion. Inlets must be protected against blockage.
3. Dams or embankments constructed of or impounding waste materials must be designed so
that at least ninety percent of the water stored during the design precipitation event can be
removed within a ten-day period.
4. For dams or embankments constructed of or impounding waste materials, at least ninety
percent of the water stored during the design precipitation event must be removed within the
ten-day period following the event.
History: Effective August 1, 1980; amended effective May 1, 1990; May 1, 1992; June 1, 1994.
General Authority: NDCC 38-14.1-03
Law Implemented: NDCC 38-14.1-24, 38-14.1-25
