Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0014 - Storage Tanks › Chapter 1 - STORAGE TANKS › Part D - UST SYSTEMS: RELEASE DETECTION › Section 1-16 - Petroleum UST Systems with a Capacity of More Than 2,000 Gallons

Current through July 13, 2024
Petroleum USTs with a capacity of more than 2,000 gallons
					 installed on or after December 1, 2005, shall be double-wall systems and
					 interstitially monitored. Petroleum USTs installed on or before November 30,
					 2005, with a capacity of more than 2,000 gallons shall be monitored at least
					 every 30 days for releases using one or more of the following methods:
(a)
Inventory Control
.
				  Inventory control is not acceptable as a leak detection method except when it
				  is combined with another method or when the UST meets the requirements of
				  Section 14(f). Product inventory control (or another test of equivalent
				  performance) shall be conducted monthly to detect a release of at least 1% of
				  throughput plus 130 gallons in the following manner:
(i) Inventory volume measurements for
				  regulated substance inputs, withdrawals, and the amount still remaining in the
				  UST shall be recorded each operating day;
(ii) The equipment used shall be capable of
				  measuring the depth of regulated substance over the full range of the UST's
				  height to the nearest one-eighth of an inch;
(iii) The regulated substance inputs shall be
				  reconciled with delivery receipts by measurement of the UST inventory volume
				  before and after delivery;
(iv)
				  Deliveries shall be made through a drop tube that extends to within 6 inches of
				  the tank bottom;
(v) Regulated
				  substance dispensing shall be metered and recorded within the local standards
				  for meter calibration or an accuracy of 6 cubic inches for every 5 gallons of
				  regulated substance withdrawn; and
(vi) Water in the bottom of the UST shall be
				  measured to the nearest one-eighth of an inch at least once a month.
(vii) Owners and/or operators using inventory
				  control shall report a suspected release under Section 19 whenever:
(A) The inventory control fails to balance
				  within 1% of total throughput plus 130 gallons for the second consecutive
				  month; or
(B) Daily over/short
				  readings show a consistent non-zero trend for two consecutive months.
(viii) The following are methods
				  of equivalent performance to inventory control:
(A) Vapor monitoring conducted in accordance
				  with Section 16(d);
(B) Groundwater
				  monitoring conducted in accordance with Section 16(e);
(C) Interstitial monitoring conducted in
				  accordance with Section 16(f);
(D)
				  Statistical inventory reconciliation conducted in accordance with Section
				  16(g);
(E) Tracer surveys conducted
				  in accordance with Section 16(h);
(F) Manual tank gauging conducted in
				  accordance with Section 15, provided the tank has a capacity of 2,000 gallons
				  or less; or
(G) Other methods
				  approved under Section 16(i), provided that the request for approval of the
				  method specifically states that the method is of equivalent performance to
				  inventory control.