Pittsburgh Zoning Map - Undermined 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 undermined areas layer, pictured above and in bold text below.

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
RCO (Registered Community Organization) Areas
City Divisions
- DPW Divisions
- Neighborhoods
- Council Districts 2012
- Council Districts 2022 (Current)
- Wards
Historic Preservation
- Mexican War Street Historic Boundary
- Individual City-Designated Properties
- Pittsburgh City Historic Districts
Environment
- RIV Riparian Buffer (125 Feet)
- Stormwater Riparian Buffer
- Floodplain Areas
- Landslide Prone
- Potential Steep Slopes Overlay Area
- Undermined Areas
Addresses
Allegheny County
City Boundaries
Imagery 2021

The Undermined Areas Layer

Overview

This layer of the interactive zoning map shows the areas of the city that were previously mined. Almost the entire portion of the city south of the rivers was mined, as were some areas between and north of the rivers. When the undermined areas 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 regulations for the Undermined Areas layer, which are copied below.

Relationship with Zoning

Additional requirements may apply to projects within the undermined layer. These regulations are located in the Environmental Overlay Districts chapter of the Zoning Code (Chapter 906).

906.05. - UM-O, Undermined Area Overlay District.
906.05.A Purpose
The UM-O, Undermined Area Overlay District regulations of this section are intended to reduce the risk of damage to property and danger to life that may be caused by subsidence of the land surface over underground mines. This objective is implemented by requiring investigation of subsurface conditions in undermined areas and by restricting development in such areas or by requiring the use of specialized construction techniques in mine hazard areas.
906.05.B.1 Mines Underlying Property
No Certificate of Occupancy application shall be approved for a use involving new construction or enlargement of an existing structure in an UM-O District until the applicant has submitted all information available from the Pennsylvania Department of Environmental Protection or its successor agencies, Bureau of Mining and Reclamation, Division of Mine Subsidence Insurance and Mine Subsidence Regulations about the location, depth and physical characteristics of any mine that underlies the subject property or adjacent properties and the likelihood of mine subsidence occurring in the pertinent area.
906.05.B.2 Single-Unit Dwellings
A Certificate of Occupancy application may be approved for zoning for construction of a single-unit residential use or for another structure that is comparable in size and construction characteristics to single-unit dwelling, provided that competent evidence is provided to the Zoning Administrator showing that the site has more than one hundred (100) feet of overburden above the mine and that there is no known history of subsidence incidents in the vicinity of the proposed construction site. The permit applicant is advised that it is possible for mine subsidence to occur and affect single-unit dwellings or other structures of comparable size and construction characteristic when such structures are placed in an undermined area even when there is more than one hundred (100) feet overburden. It is strongly recommended that the applicant follow the advice of the Bureau of Mining and Reclamation, and seek the advice of a registered professional as defined in the Land Operations Ordinance of the Pittsburgh Code of Ordinances or a geotechnical consultant with appropriate professional insurance certification and the appropriate academic credentials and professional association.
906.05.B.3 Other Development Prohibited
Until the applicant has submitted evidence that the site is reasonably safe for the construction of the proposed use, no Certificate of Occupancy application shall be approved for zoning for construction on any site that has less than one hundred (100) feet of overburden or any known history of subsidence incidents in its vicinity; for any structure that is larger or heavier than a typical single-unit dwelling; or for any use that might create a hazard to the public if damaged by subsidence. Such evidence shall be based on a site investigation performed by a registered professional as defined in the Land Operations Ordinance of the Pittsburgh Code of Ordinances Title Ten or a geotechnical consultant with appropriate professional insurance certification and the appropriate academic credentials and professional association.
906.05.B.4 Review by Chief
If the site investigations required under the UM-O District includes recommendations for any special construction techniques to ensure safe construction on an undermined site, no building permit or land operations permit shall be issued until construction plans have been approved by the Chief of the Bureau of Building Inspection as safe for the site in question, based upon the findings and recommendations of the site investigation. In the implementation of this requirement, the Chief of the Bureau of Building Inspection may require that construction plans be prepared or approved by a registered professional as defined in the Land Operations Ordinance or a geotechnical consultant with appropriate professional insurance certification and the appropriate academic credentials and professional association.

In other words, any application that includes an addition or new construction in the Undermined Areas layer must submit evidence on the status of the mine from the state. This evidence is typically a coal status report, which includes the date of last known activity in the mine and the amount of overburden between the mine and the surface. For applications involving a single-family dwelling, a geotechnical report is only required if the amount of overburden identified in the coal status report is less than 100 ft. For all other applications with additions or new construction in the undermined areas layer, a geotechnical report is required in addition to the coal status report.

Note: the code is a bit outdated regarding staff titles and office names: the Chief of the Bureau of Building Inspection is now the Director of the Department of Permits, Licenses, and Inspections (PLI); and the Pennsylvania Bureau of Mining and Reclamation, Division of Mine Subsidence Insurance and Mine Subsidence Regulations is now the Office of Active and Abandoned Mining Operations.

Challenges

It is possible for only a portion of a site to be within the Undermined Areas layer, and for the rest of the site to not be undermined. When a parcel is only partially in a layer, the challenge is the point selected to click may be in the portion not in the layer. It is important to be aware if any of the proposed development site is within the layer, and where the proposed development might be located in relation to any undermined areas on the site.

Conclusion

Start with Pittsburgh’s interactive zoning map to check if your project is in an undermined area. If it is and the application is for an addition or new construction, request a coal status report from the state to include as supplemental documentation with your zoning application. If the application is for anything other than a single-family dwelling, plan to provide a geotechnical report as well. If the application is for a single-family dwelling, ordering a geotechnical report can wait until the coal status report comes back in case the overburden is at least 100 ft., in which case the geotechnical report would not be required. If the reported overburden is exactly 100 ft., plan to double-check with review staff if a geotechnical report is required.