1. No excavation shall be made with a cut face steeper in slope than two horizontal to one vertical, except under one or more of the following conditions:
A. A governmental review agency, professional engineer or engineering geologist may classify according to the soil survey the types of soil on the site to be graded. Maximum slopes must then be determined as follows:
(1) Landslide-prone soils where slopes are greater than 25% shall have cut slopes no steeper than three horizontal to one vertical. Soil survey map symbols relative to this requirement are:
(2) Landslide-prone soils where slopes are less than 25% shall have cut slopes no steeper than two horizontal to one vertical. Soil survey map symbols relative to this requirement are:
32-B-2 65-B-2 32-C-2 65-C-2 34-B-2
65-D-2 34-C-2 67-C-2 34-D-2 67-D-2
(3) Soils which are not or have a low probability of being landslide-prone shall have a slope no steeper than one and one half horizontal to one vertical. All soil survey map symbols except the symbols listed above denote soils of low landslide probability.
B. Cut slopes which are steeper than those specified in § 9-110, Subsection 1.A., may be allowed under a grading permit, provided one or both of the following is satisfied:
(1) The material in which the excavation is made is sufficiently stable to sustain a slope steeper than the slope specified above for recognized soil conditions on the site. A written statement, signed and sealed by a professional engineer, stating that the steeper slope will have sufficient stability and that risk of creating a hazard will be slight, must be submitted to the Borough Engineer or his designee.
(2) A retaining wall or other approved support, designed by a professional engineer and approved by the Borough Engineer or his designee, is provided to support the face of the excavation.
C. The excavation is located so that a line having a slope of two horizontal to one vertical and passing through any portion of the cut face will be entirely inside the property lines of the property on which the excavation is made.
D. A written statement from a registered professional engineer, licensed by the Commonwealth of Pennsylvania, and experienced in soils engineering, certifying that he has inspected the site and that the material in which the excavation is to be made is sufficiently stable to sustain a slope steeper than two horizontal to one vertical and that said steeper slope will not endanger any property or result in property damage, is submitted to and approved by the Borough Engineer or his designee.
E. A retaining wall or other approved support designed by a registered professional engineer is provided to support the face of the excavation.
(1) A retaining wall is a structure composed of concrete, steel or other approved building material constructed for the purpose of supporting a cut or filled embankment which would otherwise not comply with the requirements of the standards set forth in this Part, and which is more than four feet in height as measured on the exposed vertical surface of the wall.
(2) If a retaining wall is constructed to satisfy a requirement of this Part, a building permit, as provided for by other Borough regulations, shall not be required. The grading permit will apply to the retaining wall, and the requirements for inspection, etc., as stated herein will be complied with.
(3) Retaining walls must be constructed in accordance with sound engineering practice. The plans submitted for approval shall bear the seal of a professional engineer.
(4) The backfilling of retaining walls and the insertion of subterranean drainage facilities shall be done strictly in accordance with the provisions of this Part and the appropriate Borough specifications.
(5) In general, where a wall is replacing an exposed slope, the vertical face of the wall shall be three feet back from the adjoining property.
(a) A special exception to this requirement may be applied for and granted by the Borough Engineer or his designee if it can be satisfactorily demonstrated that such a variance is necessary to insure normal use of the property, i.e., for a sideline driveway.
(b) An exception to the requirements of this clause may also be made when the proposed retaining wall is a joint venture between adjacent property owners, and appropriate documents so stating are filed with the application for the permit.
2. The top or bottom edge of slopes shall generally be set back from adjacent property lines or street right-of-way lines in order to permit the normal rounding of the edge without encroaching on the abutting property or street.
3. The Borough Engineer or his designee may require an excavation to be made with a cut face flatter in slope than two horizontal to one vertical if he finds the material in which the excavation is to be made unusually subject to erosion, or if other conditions exist which, under applicable engineering practice, make such flatter cut slope necessary for stability and safety.
4. Excavations adjacent to any footing, foundation or structure shall not extend below the angle of repose or natural slope of the soil under the nearest point of same unless such footing, foundation or structure is first properly underpinned or protected against settlement.
5. Before commencing any excavation which will in any way affect an adjoining property or structures thereon, the person making or causing the excavation to be made shall give notice to the owners of adjoining buildings not less than 30 days before such excavation is to be made that the excavation is to be made.
6. Guidelines for minimizing erosion and sediment in the "Erosion and Sediment Control Handbook for Allegheny County, Pennsylvania" should be followed. One or a combination of guidelines should be used to minimize hazard, depending on site conditions and proposed grading. However, the Borough Engineer or his designee may approve grading plans not meeting guidelines of the handbook if the proposed grading will not constitute a hazard. Governmental and/or engineering reports should be used as evidence that proposed grading will not constitute a hazard.
(Ord. 965, 10/13/2022)