My Credentials:
Electrical Engineering Professional
Studied Chemistry
Worked in aerospace for 5 years on electronics

Background:
Trying to sleep last night, I was scrolling (I know, that is my problem), and I stumbled across a problem that got myself thinking, and I thought, aw hell, why not post the thoughts.

Situation:
7,000 gallon US gallons in tank (Wikipedia.)
34,000 gallon storage tank of methyl methacrylate (MMA) became overheated (FOX KTVU).
Incident began at 3:30 PM PDT at GKN Aerospace (FOX KTVU).
This has been occurring for four days (Wikipedia).
There seems to be a crack occurring in the tank

Weather in Garden Grove:

Process:
Pull MSDS Sheet. Found a Safety Data Sheet from a manufacturer. I do not know if this is the manufacturer. Found data sheet from EPA. Pull up chemical specification from PubChem.
Question from my time in aerospace - is this specialty or proprietary - put this on back burner if search for MMA and company name comes up empty. Until there is a sign that this chemical is specialty, I am regarding it as the EPA and PubChem chemical with no adulterations.

From PubChem (https://pubchem.ncbi.nlm.nih.gov/compound/6658#section=Chemical-Vendors):
"Section 3.2 Experimental Properties"
3.2.1 Physical Description"
"Containers must be heavily insulated or shipped under refrigeration. An inhibitor such as hydroquinone, hydroquinone methyl ester and dimethyl t-butylphenol is added to keep the chemical from initiating polymerization. The chemical may polymerize exothermically if heated or contaminated with strong acid or base."

Screenshot of PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/6658#section=Physical-Description&fullscreen=true

Question being, is methyl methacrylate being stored with the inhibitors? Are these inhibitor chemicals denser than the methyl methacrylate? Do they need to be agitated during shipment? -  Not important for the discussion at the moment.
Is the inhibitor chemical still stored within the container prior to use? Is this enough to prevent polymerization? - These are important questions to answer.
According to the BASF Safety Data Sheet for Methyl Methacrylate, Page 6, "Never use tanks with inert-gas installation for storage."

Screenshot of BASF Safety Data Sheet: https://download.basf.com/p1/000000000030041969_SDS_GEN_US/en_US/METHYLMETHACR._30041969_SDS_GEN_US_en_4-0.pdf

This indicates to me that the stored methyl methacrylate does not have inert chemicals stored with it. This may already be known. Once again, I am not a chemist, nor do I claim to be. I took a few classes once upon a time, please refer to my LinkedIn profile as to where.

"6. Chemical Vendors"

Screenshot of PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/6658#section=Chemical-Vendors&fullscreen=true

This chemical is widely available. If there is something special about it, the company shall have it on file, potentially as proprietary. If I were in person, I would ask the manufacturer for the supplier they sourced from to determine which safety data sheet to use. This will have the safety requirements required to handle during a spill. If they do not, there are other sources listed below, I like to have 3 on hand at least for most projects. (Now watch, I have to mix it up. Have to pick 4 sources at least.)

Screenshot of PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/6658#section=Fire-Fighting&fullscreen=true

Above are the Fire Fighting clauses.

Screenshot of PubChem: https://pubchem.ncbi.nlm.nih.gov/compound/6658#section=Spillage-Disposal&fullscreen=true

From the Safety Data Sheet (https://download.basf.com/p1/000000000030041969_SDS_GEN_US/en_US/METHYLMETHACR._30041969_SDS_GEN_US_en_4-0.pdf):
5. Fire-Fighting Measures
"Extinguishing media
Suitable extinguishing media:
dry powder, water spray, carbon dioxide, foam
Unsuitable extinguishing media for safety reasons:
water jet
Additional information:
Use extinguishing measures to suit surroundings.
Special hazards arising from the substance or mixture
Hazards during fire-fighting:
Risk of violent self-polymerization if overheated in a container. Cool endangered containers with water-spray.
The product is combustible. See SDS section 7 - Handling and storage.
Advice for fire-fighters
Protective equipment for fire-fighting:
Firefighters should be equipped with self-contained breathing apparatus and turn-out gear. Special protective equipment for firefighters
Further information:
Extend fire extinguishing measures to the surroundings. Fight fire from maximum distance. Vapours are heavier than air and may accumulate in low areas and travel a considerable distance up to the source of ignition.
In case of a fire in the vicinity a restabilization system should be used if the temperature in the bulk storage-tank reaches 45°C. Evacuate area of all unnecessary personnel. In case of a fire in the vicinity evacuate all personnel in a greater area if the temperature in the bulk storage-tank reaches 60°C.
Dispose of fire debris and contaminated extinguishing water in accordance with official regulations.
Impact Sensitivity:
Remarks: Based on the chemical structure there is no shock-sensitivity."

Screenshot of BASF Safety Data Sheet: https://download.basf.com/p1/000000000030041969_SDS_GEN_US/en_US/METHYLMETHACR._30041969_SDS_GEN_US_en_4-0.pdf

6. Accidental release measures
"Methods and material for containment and cleaning up
For large amounts: Pump off product.
Spills should be contained, solidified, and placed in suitable containers for disposal. Dispose of absorbed material in accordance with regulations. Ensure adequate ventilation. Suppress gases/vapours/mists with water spray jet. Clean contaminated floors and objects thoroughly with water and detergents, observing environmental regulations. Cleaning operations should be carried out only while wearing breathing apparatus. Pick up with suitable appliance and dispose of."

7. Handling and Storage
"Precautions for safe handling"
"Heated containers should be cooled to prevent polymerization. If exposed to fire, keep containers cool by spraying with water. Emergency cooling must be provided for the eventuality of a fire in the vicinity." - Firefighters have been performing this measure (FOX KTVU).

From the Chemical Book (https://www.chemicalbook.com/msds/methyl-methacrylate.htm):
"Section 8: Exposure controls/personal protection"
"Splash contact Material: Butyl-rubber
Minimum layer thickness: 0,3 mm Break through time: 66 min" - Context indicates these precautions may be for general use - Gloves for handling from Safety Data Sheet - Question - Does the fire department have these types of gloves/safety protection to handle issue? Is this the only material required? According to the U.S. Fish and Wildlife Service, on page 4 of 6, Butyl Rubber Gloves are available (https://www.fws.gov/sites/default/files/policy/pdfs/e4241fw3.pdf). The question being, are these the appropriate weight for European standards, and for American Standards?

Screenshot of U.S. Fish and Wildlife Service: https://www.fws.gov/sites/default/files/policy/pdfs/e4241fw3.pdf