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SITING NEAR HAZARDOUSOPERATIONS

24 CFR 51C

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Acceptable Separation Distance (ASD) 24 CFR Part 51 Subpart C

Regulation Applies to stationary, above-ground storage containers holding:– more than 100 gallons capacity of liquid industrial fuels (such as gasoline, fuel oil, kerosene and crude oil) and

– more than 100 galllons of hazardous liquids or gases that are not liquid industrial fuels

Siting of HUD-Assisted Projects Near Hazardous Operations

To prevent injury to project occupants and damage to property

Sets standards for determining safe distance from stationary aboveground storage tanks that are more than 100 gallons in size, and within line-of-sight of the project

Establishes acceptable separation distances for blast overpressure from explosive substances and thermal radiation from flammable substances

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Blast Overpressure

The ASD standard for blast overpressure is 0.5 PSI

Equivalent to the overpressure produced by 1 pound of TNT

THERMAL RADIATIONTHERMAL RADIATION

The standard for thermal radiation is set at 1,500 BTU/ft.2

Human exposure to this thermal radiation causes intolerable pain after 15 seconds.

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Examples of Hazardous Operations Applicable to 51C

Bulk fuel storage and distribution facility

Examples of Hazardous Operations Applicable to 51C

Petrochemical plant

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What is a “HUD-Assisted Project”?(section 51.201- p.18)

“ ...development, construction, rehabilitation, modernization or conversion with HUD subsidy …of any project …intended for residential, institutional, recreational, commercial or industrial use...

“rehabilitation” and “modernization” refer only to such repairs and renovation....as will result in an increased number of people being exposed...by increasing density, conversion to habitation or making a vacant building habitable.”

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Exclusions: Standards do not apply

UndergroundStorage Containers

Natural gas holdersWith Floating Tops

Exclusions: Standards do not apply

High PressurePipelines

Mobile tanks en Route

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The Regulation does not apply to:

• Employees of facilities which manage or process explosive or flammable materials (OSHA covers employee safety)

• Individual fuel supply for one to four family housing units.

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Assessment Process—How and WhatStep 1:

Define Project

Step 2:

Gather Data for ASD

Step 3:

Calculate ASD

Step 4:

Does it meet standard?

Step 5: Mitigation

•Project •Site Location•Maps, site plans or photos

Identify:Tanks within a mile Capacity (in gallons)Chemical namePhase (gas or liquid)

Determine and apply mitigation option

No further action required

What if the proposed project still cannot meet the ASD?

• Consider Mitigation Options

–Burying the hazard

–Modifying the building design to compensate for the ASD

–Choosing a different site

–Resorting to a barrier

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ASD Calculations

• On line Assessment tool to calculate ASD http://www.hud.gov/offices/cpd/environment/asdCalculator.cfm• The manual calculation in the guidebook “Siting of HUD-Assisted Projects Near Hazardous Facilities” and the Regulation (24 CFR Part 51 Subpart C) remains viable.

Where to find the HUD-Hazard Guidebook-

ASD Determination Procedureshttp://www.hud.gov/offices/cpd/environment/training/guidebooks/hazfacilities

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Mitigation Module

Module provides mitigation options if the ASD cannot be met.

•No action alternative

•Other reasonable alternatives

•Mitigation

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Containers with DikesThe diked area provides some spill protection

ASD calculations for above ground storage containers using dikes – use diked area

Container

Dike

Self contained above ground Storage Tanks For SCAC containers (Self Contained Above Ground Container) ASD calculations must be done for containers without a dike area – tank volume

SCAC-Use tank volume

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Case Study: River SubdivisionStep 1: Understand the Project

–Housing Project for Adults

–Location: Happy Valley, CA

– Hazardous Operations in the Vicinity:

• Bulk Fuels Storage facility with

• 10 – 30,000 gallon and

• 1 – 18,000 gallon containers

• all storing Liquid Propane Gas (LPG)

Step 2: Gather Data

Use photos and plans of the project site

Proposed Subdivision

Propane Tanks

Available Distance from the hazard to the site

Two Structures partially block Line of Sight

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ASD Calculator Example: Happy Valley

Step 4- Does the project meet the Standards?

ASD for Buildings = 242.26 ft.

ASD BO = 674.27 feet

ASD for People = 1140 ft

Proposal meets ASD for blast over pressure for buildings and ASD for thermal radiation for buildings but not the ASD for thermal radiation for people.

Distance from Project site to hazard = 680 ft

Result : Mitigation is required for the proposal to

meet ASD of thermal radiation for people

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Step 5 - Happy Valley Result

• The two building structures provided a reduction on the Thermal Heat Flux (heat) transmitted to the site. The intervening buildings reduced the heat flux to safe levels (78 BTU/ft2 – hr) acceptable to the Department, with the standard of thermal radiation for people of 450 BTU/ft2 – hr.

The Project was ACCEPTED! WHY?

* Only Licensed PE can make this Determination

ASD Appendix F (Thermal Radiation) p.51

Volume ASD ASD(gals.) Fire width Bldgs People

People

Undiked tank 100 20 17 107

10,000 200 145 720

Diked tank 100 10 10 60

10,000 100 76 400

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ASD Appendix G

(Blast Overpressure) p.52

Tank Volume ASD

100 115

1,000 220

10,000 465

1,000,000 2,150

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