CLASSIFICATION AND DESIGN CRITERIA
§ 105.91. Classification of dams and reservoirs.
(a) A dam or reservoir shall be classified in accordance with size and the hazard potential which might occur in the event of an operational or structural failure. In approving a hazard potential 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) The following shall be the classifications and descriptions as used in this subchapter:
SIZE CLASSIFICATION*
Class
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
| Class | 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 |
*Note: Size classification may be determined by either storage or height of structure, whichever gives the higher category.
HAZARD POTENTIAL CLASSIFICATION
Extent of Development
Category
Loss of Life
Economic Loss
1
Substantial Excessive (extensive residential, commercial, agricultural and substantial public inconvenience) 2
Few (no rural communities or urban developments and no more than a small number of habitable structures) Appreciable (damage to private or public property and short duration public inconvenience) 3
None expected (no permanent structure for human habitation) Minimal (undeveloped or occasional structures with no significant effect on public inconvenience)
Extent of Development
| Category | Loss of Life | Economic Loss |
| 1 | Substantial | Excessive (extensive residential, commercial, agricultural and substantial public inconvenience) |
| 2 | Few (no rural communities or urban developments and no more than a small number of habitable structures) | Appreciable (damage to private or public property and short duration public inconvenience) |
| 3 | None expected (no permanent structure for human habitation) | Minimal (undeveloped or occasional structures with no significant effect on public inconvenience) |
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).
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. Immediately preceding text appears at serial pages (117680) and (149139).
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 permit applications—information and fees); 25 Pa. Code § 105.20 (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).
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