Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0011 - Water Quality › Chapter 17 - STORAGE TANKS › Part D - UST SYSTEMS: RELEASE DETECTION › Section 17-16 - 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
					 shall be monitored at least every thirty (30) days for releases using one or
					 more of the following methods:
(a)
Inventory control
. Inventory control is never acceptable as a
				  leak detection method except when it is combined with another method. Product
				  inventory control (or another test of equivalent performance) shall be
				  conducted monthly to detect a release of at least 1.0 percent (1%) of
				  throughput plus one hundred thirty (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 USTs
				  height to the nearest one-eighth (1/8) 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 six (6)
				  inches of the Storage Tank bottom;
(v) Dispensing of regulated substances shall
				  be metered and recorded within the local standards for meter calibration or an
				  accuracy of six (6) cubic inches for every five (5) gallons of regulated
				  substance withdrawn; and
(vi) Water
				  in the bottom of the UST shall be measured to the nearest one-eighth (1/8) of
				  an inch at least once a month.
(vii)
				  Owners and/or operators using inventory control may combine this method with
				  tank tightness testing at least every five (5) years until December 22, 2008,
				  or until ten (10) years after the UST itself first met the requirements of
				  Section 6(a), whichever is sooner;
(viii) Owners and/or operators using
				  inventory control shall report a suspected release under Section 19(c) of this
				  chapter whenever:
(A) The inventory control
				  fails to balance within 1.0 percent (1%) of total throughput plus one hundred
				  thirty (130) gallons for the second consecutive month;
(B) More than 20 daily readings are either
				  positive or negative for the second consecutive month; or
(C) A graph of the daily over/short readings
				  shows a consistent non-zero trend for two (2) consecutive
				  months.
(ix) The following
				  methods are methods of equivalent performance to inventory control:
(A) Vapor Monitoring conducted in accordance
				  with section 16(d) of this chapter;
(B) Groundwater Monitoring conducted in
				  accordance with section 16(e) of this chapter;
(C) Interstitial Monitoring conducted in
				  accordance with Section 16(f) of this chapter;
(D) Statistical Inventory Reconciliation
				  conducted in accordance with Section 16(g) of this chapter;
(E) Tracer Surveys conducted in accordance
				  with Section 16(h) of this chapter;
(F) Passive Acoustical Sensing conducted in
				  accordance with Section 16(k) of this chapter; and
(G) Other methods approved under Section
				  16(j) of this chapter, providing that the approval of the method specifically
				  states that the method is of equivalent performance to inventory
				  control.