Section 105.91. Classification of dams and reservoirs

(a) A dam or reservoir shall be classified in accordance with Size Category and the Hazard Potential Category which might occur in the event of an operational or structural failure. In approving a classification, the Department will consider, without limitation:

(1) The height of the dam and storage capacity of the reservoir.

(2) The physical characteristics and extent of actual and projected development of the dam site and downstream areas.

(3) The relationship of the site to existing or projected industrial, commercial and residential areas and other land uses downstream which may be affected by a dam failure.

(b) Size Category will be determined by either storage or height of structure, whichever results in the higher category. Hazard Potential Category will be determined by either loss of life or economic loss, whichever results in the higher category. The following shall be the categories and descriptions as used in this subchapter:

SIZE CATEGORY

Category	Impoundment Storage (Acre Feet)	Dam Height (Feet)
A	Equal to or greater than 50,000	Equal to or greater than 100
B	Less than 50,000 but greater than 1000	Less than 100 but greater than 40
C	Equal to or less than 1000	Equal to or less than 40

HAZARD POTENTIAL CATEGORY

Category	Population at Risk	Economic Loss
1	Substantial (Numerous homes or small businesses or a large business or school).	Excessive such as extensive residential, commercial, or agricultural damage, or substantial public inconvenience.
2	Few (A small number of homes or small businesses.)	Appreciable such as limited residential, commercial, or agricultural damage, or moderate public inconvenience.
3	None expected (no permanent structures for human habitation or employment.)	Significant damage to private or public property and short duration public inconvenience such as damage to storage facilities or loss of critical stream crossings.
4	None expected (no permanent structures for human habitation or employment.)	Minimal damage to private or public property and no significant public inconvenience.

The provisions of this § 105.91 adopted September 10, 1971, effective September 11, 1971, 1 Pa.B. 1804; amended August 11, 1978, effective August 28, 1978, 8 Pa.B. 2229; amended September 26, 1980, effective September 27, 1980, 10 Pa.B. 3843; amended October 11, 1991, effective October 12, 1991, 21 Pa.B. 4911; amended January 7, 2011, effective January 8, 2011, 41 Pa.B. 219. Immediately preceding text appears at serial pages (313670) and (207719) to (207720).

Notation

Authority

The provisions of this § 105.91 amended under the Dam Safety and Encroachments Act (32 P. S. § § 693.1–693.27); The Clean Streams Law (35 P. S. § § 691.1—691.1001); section 7 of the act of June 14, 1923 (P. L. 704, No. 294) (32 P. S. § 597); sections 514, 1901-A, 1908-A, 1917-A and 1920-A of The Administrative Code of 1929 (71 P. S. § § 194, 510-1, 510-8, 510-17 and 510-20); and the Flood Plain Management Act (32 P. S. § § 679.101—679.601).

Cross References

This section cited in 25 Pa. Code § 87.112 (relating to hydrologic balance: dams, ponds, embankments and impoundments—design, construction and maintenance); 25 Pa. Code § 90.112 (relating to hydrologic balance: dams, ponds, embankments and impoundments—design, construction and maintenance); 25 Pa. Code § 105.12 (relating to waiver of permit requirements); 25 Pa. Code § 105.13 (relating to regulated activities—information and fees); 25 Pa. Code § 105.13b (relating to proof of financial responsibility); 25 Pa. Code § 105.53 (relating to inspections by owners and inspection reports); 25 Pa. Code § 105.98 (relating to design flood criteria); and 25 Pa. Code § 105.442 (relating to authorization for general permits).