5/29/262 UPDATED using NFPA 30, Tables 22.4.1.5 and 22.4.1.1(b). It was brought to my attention that CA has more stringent requirements, so I have updated my post using NFPA 30, Chapter 22 – Storage of Ignitible (Flammable or Combustible) Liquids in Tanks — Aboveground Storage Tanks. My previous post was using IFC Tables.
Using Google Maps and Information from the Fire Authority dealing with the Methyl methacrylate (MMA) event in Garden Grove, CA, I was puzzled by the location of the MMA tank(s). We know at least one (1) of the tanks shown below is an MMA based on the news accounts, videos, and images. We don’t know what the other two tanks contain.
MMA is a Class 2 Unstable (Reactive) Flammable Liquid and would fall under Chapter 57 of the IFC. I am NOT sure what the CA Fire Code calls it or what the state requirements are; however, in my 20 years of working in CA, I have always found the state code to be more restrictive than the IFC. But this analysis is done using the IFC 2024.
Below, I use aerial imagery and the “Tables” from NFPA 30 to explain the “Safe Distances” based on this material and my curiosity about how these MMA Tank(s) were placed this close to the property line. I am sure this event will prompt a thorough “After Action Analysis” of the failures that led up to it, access to these tanks, and the distance to the property line(s).
NOTE: shutting down that rail spur will be an expensive insurance claim as every business on that spur has a “loss of business” claim, even if they are outside the EVAC zone.
5704.2.9.6.1.4 Location of tanks storing unstable liquids. Above-ground tanks for the storage of unstable liquids shall be located in accordance with Table 22.4.1.5 in the 2021 edition of NFPA 30.
22.4.1.5 Tanks storing unstable liquids shall be located in accordance with Table 22.4.1.5 and Table 22.4.1.1(b).
| Table 22.4.1.5 Location of Aboveground Storage Tanks Storing Unstable Liquids | ||||
| Minimum Distance (ft) | ||||
| Type of Tank | Protection | From Property Line that Is or Can Be Built Upon, Including the Opposite Side of a Public Way | From Nearest Side of Any Public Way or from Nearest Important Building on the Same Propertya | |
| Horizontal and vertical tanks with emergency relief venting to permit pressure not in excess of a gauge pressure of 2.5 psi (17 kPa) | Tank protected with any one of the following: 1) approved water spray, 2) approved inerting, 3) a approved insulation and refrigeration, 4) approved barricade | Value in Table 22.4.1.1(b) but not less than 25 ft | Not less than 25 ft | |
| Protection for exposuresb | 2.5 × value in Table 22.4.1.1(b) but not less than 50 ft | Not less than 50 ft | ||
| None | 5 × value in Table 22.4.1.1(b) but not less than 100 ft | Not less than 100 ft | ||
| Horizontal and vertical tanks with emergency relief venting to permit pressure over a gauge pressure of 2.5 psi (17 kPa) | Tank protected with any one of the following: 1) approved water spray, 2) approved inerting, 3) a approved insulation and refrigeration, 4) approved barricade | 2 × value in Table 22.4.1.1(b) but not less than 50 ft | Not less than 50 ft | |
| Protection for exposuresb | 4 × value in Table 22.4.1.1(b) but not less than 100 ft | Not less than 100 ft | ||
| None | 8 × value in Table 22.4.1.1(b) but not less than 150 ft | Not less than 150 ft | ||
| For SI units, 1 ft = 0.3 m. aSee NFPA 69. bSee definition 3.3.46, Protection for Exposures. | ||||
| Table 22.4.1.1(b) Reference Table for Use with Tables 22.4.1.1(a), 22.4.1.3, and 22.4.1.5 | |||
| Minimum Distance (ft) | |||
| Tank Capacity (gal) | From Property Line that Is or Can Be Built Upon, Including the Opposite Side of a Public Way | From Nearest Side of Any Public Way or from Nearest Important Building on the Same Property | |
| 275 or less | 5 | 5 | |
| 276 to 750 | 10 | 5 | |
| 751 to 12,000 | 15 | 5 | |
| 12,001 to 30,000 | 20 | 5 | |
| 30,001 to 50,000 | 30 | 10 | |
| 50,001 to 100,000 | 50 | 15 | |
| 100,001 to 500,000 | 80 | 25 | |
| 500,001 to 1,000,000 | 100 | 35 | |
| 1,000,001 to 2,000,000 | 135 | 45 | |
| 2,000,001 to 3,000,000 | 165 | 55 | |
| 3,000,001 or more | 175 | 60 | |
| For SI units, 1 ft = 0.3 m; 1 gal = 3.8 L. | |||