Pittsburgh Zoning Map - Potential Steep Slopes Layer

By Carolyn Ristau

Introduction

Pittsburgh’s interactive zoning map includes many layers besides the zoning districts, most of which relate to requirements within or adjacent to the zoning code. For an overview on how to use the interactive zoning map, see our introductory post.

To select different layers, click the stack of paper in the upper right corner. The layers available are listed below. Today’s post features the steep slope or “Potential Steep Slope Overlay Area” layer, pictured above and in bold text below.

1. Zoning

   • Zoning Districts

   • Zoning Districts Outlines

   • Zoning Max. Height Overlay

   • Height Reduction Zone Overlay

   • 1500’ Major Transit Buffer

   • Parking Reduction Areas

   • North Side Commercial Parking Prohibited Area

   • Baum Centre Zoning Overlay

   • Inclusionary Housing Overlay District

2. RCO (Registered Community Organization) Areas

3. City Divisions

   • DPW Divisions

   • Neighborhoods

   • Council Districts 2012

   • Council Districts 2022 (Current)

   • Wards

4. Historic Preservation

   • Mexican War Street Historic Boundary

   • Individual City-Designated Properties

   • Pittsburgh City Historic Districts

5. Environment

   • RIV Riparian Buffer (125 Feet)

   • Stormwater Riparian Buffer

   • Floodplain Areas

   • Landslide Prone

   • Potential Steep Slopes Overlay Area

   • Undermined Areas

6. Addresses

7. Allegheny County

8. City Boundaries

9. Imagery 2021

The Steep Slope Layer

Overview

This layer of the interactive zoning map shows areas of the city that are likely to have slopes or hills with at least a 25% grade. When the steep slope layer is clicked, the pop-up box confirms that the point clicked is in the layer and provides a link to the zoning code section that discusses steep slope regulations (Section 906.08).

Relationship with Zoning

The zoning code contains several regulations pertaining to projects that impact slopes of 25% or greater. These regulations are found in two sections of the code:

• the Environmental Overlay Districts (Chapter 906)

• the Environmental Performance Standards (Chapter 915)

906.08. - SS-O, Steep Slope Overlay District.

906.08.A   Purpose

1. Create a Steep Slope Overlay District (SS-O) that includes any land comprising a steep slope (i.e. a natural slope of twenty-five (25) percent or greater).

2. Recognize the importance of the City's steep slopes in defining the character of Pittsburgh.

3. Assure that the steep slope site is appropriate for development considering natural site limitations, associated hazards, public safety, and the need to provide public services and infrastructure.

4. Assure that the design of the proposed development responds to the site's limitations and attributes.

906.08.C   Development on Slopes in the SS-O district

906.08.C.1   Applicability

To ensure that development occurs in a manner that protects the natural and topographic character of slopes twenty-five (25) percent or greater, all uses and structures permitted in the base underlying district shall be reviewed and approved by the Planning Commission per the procedures of this Section.

The wording of the applicability section suggests that any application for use or structures in the mapped layer requires review and approval by Planning Commission. However, the purpose identifies the Steep Slope Overlay as where there are “natural” slopes of 25% or greater. While Pittsburgh has many slopes as shown in the map layer, most were previously developed and therefore are no longer natural. This reduces the number of applications that require Planning Commission review and approval to a small handful.

On the other hand, the slope or grading regulations in the Environmental Performance Standards Chapter apply regardless of whether the slopes are natural or not.

915.02. - Environmental Standards.

915.02.A   Grading Standards

915.02.A.1   The Grading, Cut, and Fill Standards of this Section Shall Apply to All Slopes.

a. To the maximum extent feasible, the grading shall preserve the natural landforms of the site;

b. To the maximum extent feasible, cutting, filling and severe benching or terracing of existing slopes to create additional building area or larger building sites shall be avoided;

c. Finished grades of fifteen (15) percent or less are strongly encouraged. Cut or filled slopes shall not exceed twenty-five (25) percent unless:

(1) The applicant submits a geotechnical investigation report that certifies the safety and suitability of such slopes; and

(2) The applicant proposes the use of walls, terraces, or other methods at intervals of not less than ten (10) feet to create planting beds that will stabilize the slope, and such measures are approved in the geotechnical investigation report as sufficient to ensure the stability of the slope and ensure that such slope shall pose no significant risk of danger to any property or public improvements located on or off the proposed development site.

d. The top and bottom of the cut or filled slopes shall be located no less than five (5) feet from any property line, street, building, parking area, or other developed area.

e. Retaining walls or gabions may be permitted to support steep slopes, but shall not exceed ten (10) feet in height.

f. Retaining walls shall follow the existing hillside contours if physically feasible and shall avoid visible unnatural straight slope faces. Walls shall be of a color that is compatible with natural rock outcroppings that occur on Pittsburgh hillsides.

In other words, the existing grading should be left in place wherever possible. If changes to the site grading are required and the finished grade will be 25% or more, a geotechnical report is required. Retaining walls not more than 10 feet high and spaced at least 10 feet apart are permitted.

For more information about geotechnical reports, see the city’s website.

Challenges

The steep slope layer approximates where slopes of 25% or greater are located within the city. If a proposed project appears in or near the steep slopes layer, a grading plan will be required to confirm the existing and proposed slope conditions. It isn’t until after that plan has been received and reviewed that it can be determined if a geotechnical report will be required as described above.

There is also a subjective element in determining if an existing 25% slope is natural. Perhaps, the best explanation is that you know it when you see it. Often the determination is based on whether the site was previously developed. However, a previously developed site may include an undeveloped steep slope. This means that the determination of whether Planning Commission review is required may not be made until after the initial staff review.

Conclusion

Start with Pittsburgh’s interactive zoning map to check if your project is potentially in a steep slope area. If it is, consider minimizing any impact to the steepest portions of the site and concentrating planned development in the less steep or previously regraded areas. Also, on projects that are potentially in a steep slope area, submit thorough documentation of the existing and proposed conditions. Consider planning ahead by preparing a geotechnical report if the project impacts a 25% or greater slope. Also include extra margins on money and time, in case the preliminary zoning review returns a determination that a geotechnical report and/or Planning Commission review is required.