Explosive and Flammable Facilities

Introduction

There are inherent potential dangers associated with locating HUD-assisted projects near hazardous facilities which store, handle, or process hazardous substances of a flammable or explosive nature. Project sites located too close to facilities handling, storing or processing conventional fuels, hazardous gases or chemicals of an explosive or flammable nature may expose occupants or end-users of a project to the risk of injury in the event of an explosion.

Blast overpressure and thermal radiation standards are used as a basis for calculating acceptable separation distances (ASDs) for HUD-assisted projects from specific, stationary hazardous operations which store, handle, or process substances of fire or explosive prone nature. HUD-assisted projects must meet ASDs or else mitigation measures must be undertaken.

HUD Guidance

When considering explosive and flammable facilities in the context of HUD-assisted projects, two lines of inquiry are appropriate:

1. Aboveground stationary storage tanks near the project

Does this project include any of the following activities: development, construction, rehabilitation that will increase residential densities, or conversion?

If so, within 1 mile of the project site, are there any current or planned stationary aboveground storage containers:

  • Of more than 100 gallon capacity, containing common liquid industrial fuels OR 
  • Of any capacity, containing hazardous liquids or gases that are not common liquid industrial fuels?

For a list of common industrial fuels, consult Appendix I of the Regulation and HUD’s guidebook “Acceptable Separation Distance.” Stationary aboveground containers that store natural gas and have floating tops are excluded from 24 CFR 51, Subpart C as well as underground storage containers, mobile conveyances (tank trucks, barges, rail road tank cars), and pipelines, such as high pressure natural gas transmission pipelines or liquid petroleum pipelines. If your project is a single family (1-4 unit) FHA-insured property, do not include/identify tanks that are ancillary to the operation of your project (e.g., comfort heating, cooking, water heating) because they are excluded from 24 CFR 51, Subpart C. 

Is the Separation Distance from the project acceptable based on standards in the regulation?

The Acceptable Separation Distance (ASD) can be calculated based on the volume of the container, the contents, and whether or not the container is diked. A diked container is not the same as a double walled container. A doubled-walled container, for ASD calculations, is a container without a dike, and it shall be evaluated as a single-walled container. The regulation only considers storage tank contents that are products classified as flammable or combustible. This information can be found in the Material Safety Data Sheet. Once the volume of the container (gallons), dike dimensions, and phase of state of the product (liquid or gas) are known, the ASD can be calculated by either using the electronic calculator.

The ASD is measured from the center of the assessed container to the perimeter of the proposed HUD–assisted project site. If the ASD is not met, mitigation is required, or another site must be considered. Options to mitigation are discussed in the HUD guidebook Acceptable Separation Distance.

If the separation distance is not acceptable, a barrier is required to mitigate the project. Otherwise, the project should be moved to a different location. Work with a licensed engineer to determine whether an existing barrier (natural or man-made) is sufficient mitigation or to design a barrier. For more guidance on barriers and mitigation, contact Nelson Rivera, a licensed engineer at HUD, at nelson.a.rivera@hud.gov or 202-402-4455. 

2. Hazardous facilities included in the project

Does the proposed HUD-assisted project include a hazardous facility (a facility that mainly stores, handles or processes flammable or combustible chemicals such as bulk fuel storage facilities and refineries)?

If so, is the hazardous facility located at an acceptable separation distance from residences and any other facility or area where people may congregate or be present? See guidance above on calculating the ASD.

Compliance and Documentation

The environmental review record should include:

One of the following on aboveground storage tanks:

  • A determination that the project does not include development, construction, rehabilitation that will increase residential densities, or conversion
  • Evidence that within one mile of the project site there are no current or planned stationary aboveground storage containers of more than 100-gallon capacity containing common liquid industrial fuels or of any capacity containing hazardous liquids or gases that are not common liquid industrial fuels
  • A determination along with all supporting documentation that the separation distance of such containers from the project is acceptable
  • Documentation of the existing or planned barrier that would serve as sufficient mitigation, including correspondence with a licensed engineer

AND one of the following on hazardous facilities:

  • A determination that the project does not include a hazardous facility
  • A determination along with all supporting documentation that the hazardous facility is located at an acceptable separation distance from residences and any other facility or area where people may congregate or be present
  • Documentation of the existing or planned barrier that would serve as sufficient mitigation, including correspondence with a licensed engineer

View Explosive and Flammable Facilities - Worksheet.

View Explosives - Partner Worksheet.