Minnesota Administrative Rules
Agency 144 - Health Department
Chapter 4720 - PUBLIC WATER SUPPLIES
Part 4720.3960 - CHEMICAL STORAGE

Subpart 1. Storage space.

Storage space must provide for:

Subp. 2. Containers.

Covered or unopened shipping containers must be provided for storage unless the chemical is transferred into an approved covered storage unit. Solution tanks must have overlapping covers.

Subp. 3. Capacity.

Solution storage or day tanks supplying feeders directly must have sufficient capacity for one day of operation. When the chemical solution is prepared from a powder or slurry, two solution tanks are required to assure continuity of feed.

Subp. 4. Storage containers.

Storage must be constructed of or lined with materials compatible with the chemical being handled.

Subp. 5. Mixing equipment.

Mixing equipment must be provided where necessary to assure a uniform chemical solution strength.

Subp. 6. Measurements.

Means must be provided to accurately determine the amount of chemical applied either by measurement of the solution level in the tank or by weighing scales. A meter must be provided on the water fill line to a fluoride saturator. Liquid chemical storage tanks must have a liquid level indicator.

Subp. 7. Drainage.

Means to drain tanks must be provided in the storage space, but there must be no direct connection between any drain piping and a sewer. Drain piping must terminate at least two pipe diameters, but not less than three inches, above the overflow rim of a receiving sump, conduit, or waste receptacle.

Subp. 8. Overflow pipes.

Overflow pipes must be turned downward, be screened, have a free discharge, and be in a conspicuous location.

Subp. 9. Subsurface storage.

Where subsurface locations for solution or storage tanks are provided, the tanks must be free from sources of possible contamination and located to assure drainage for groundwater, accumulated water, chemical spills, and overflows.

Subp. 10. Compatibility of chemicals.

Incompatible chemicals must not be stored or handled in common areas.

Subp. 11. Venting.

Gases from feeders, storage, and equipment exhausts must be conveyed to the outside atmosphere above grade and remote from air intakes. Acid storage tanks must be vented to the outside but not through vents in common with day tanks.