(1) An owner and permittee using inventory
control as a release detection method must meet this rule's requirements.
Inventory control may not be used as a release detection method for underground
Use of inventory
control as a release detection method is allowed for a period of:
(a) Ten years after the installation of the
UST system; or
(b) Ten years after
the UST system achieved compliance with corrosion protection requirements;
(c) In no case may inventory
control be used as a primary release detection method after December 22, 2008;
After the period of use has
expired as listed in subsections (a) through (c) of this section, an owner and
permittee must use one of the release detection methods in OAR 340-150-0435
(3) Regulated substance (i.e., product)
inventory control must be recorded daily and reconciled monthly to detect a
release of at least 1.0 percent of flow-through plus 130 gallons on a monthly
(4) Inventory volume
measurements for regulated substance inputs (deliveries), withdrawals and the
amount still remaining in the UST must be recorded each operating
(5) The equipment used to
measure the level of regulated substance in the UST (e.g., stick or automatic
tank gauge) must be capable of measuring the level of the regulated substance
over the full range of the tank's height to the nearest one-eighth of an
(6) Regulated substance
inputs must be reconciled with delivery receipts by measuring the tank
inventory volume before and after each delivery.
(7) Regulated substance deliveries must be
made through a drop tube that extends to within one foot of the tank bottom. To
meet Stage I air quality vapor control requirements, drop tubes must be within
six inches of the tank bottom.
Regulated substance dispensing must be metered and recorded within the local
standards for meter calibration or an accuracy of six cubic inches for every
five gallons of the regulated substance withdrawn.
(9) The measurement of any water level in the
bottom of the tank must be made to the nearest one-eighth of an inch at least
once a month.
inventory reconciliation (positive or negative) that exceeds the comparison
number of 1.0 percent of flow-through plus 130 gallons or greater leak rate in
any single month is considered to be a release detection failure. If this
occurs, an owner and permittee must:
Report to DEQ a release detection failure that occurs for two consecutive
months within 24 hours as a suspected release (OAR 340-150-0500
immediately begin investigation as 340-150-0510 specifies; and
(b) Immediately investigate all
larger-than-normal or reoccurring variations in results, including widely
fluctuating water levels in the UST, and report such variations to DEQ as a
suspected release if the variation cannot be accounted for, without waiting to
obtain a second month of data.
An owner and permittee must have USTs
tightness tested (OAR 340-150-0445
) at least once every five years when
inventory control is used as the sole or primary release detection
(12) An owner and permittee
must retain at a minimum the most current 12 consecutive months of release
detection records and the last two tightness test results.
An owner and permittee may use the
practices described in the American Petroleum Institute RP 1621, "Bulk Liquid
Stock Control at Retail Outlets" to comply with the requirements of this rule.
[Note: Publications referenced are available from DEQ or from