4.6 Statistical Inventory Control (SIR)
Statistical Inventory Control (aka SIR or Statistical Inventory Reconciliation) is a method of leak detection that uses the same data that you would collect to perform Inventory Control. This includes:
1. tank inventory (in gallons)
2. total daily withdrawals (amount of product removed from the tank in gallons)
3. total daily deposits or transfers (amount of product added to the tank in gallons)
As the name implies, statistical analysis is performed on that data to identify trends to determine whether a leak exists in the UST System. SIR can be used on both tanks and piping, either together or separate.
If you are using SIR as the method of leak detection you must submit your inventory, transfer and withdrawal data to the SIR vendor within four (4) business days of the end of each month.
SIR vendors are required to submit to the UST owner / operator the results of their analysis within ten (10) business days after the postmark when the data was submitted by the UST owner or operator.