020-1 Wyo. Code R. § 1-15 - Petroleum USTs with a Capacity of 2,000 Gallons or Less

Tanks installed on or after December 1, 2005, shall be double-wall systems and interstitially monitored. Tanks installed on or before November 30, 2005, shall be monitored for releases at least every 30 days using one of the methods listed in Section 16. Tanks with a capacity of 550 gallons or less and tanks with a capacity of 551 to 1,000 gallons that meet the tank diameter criteria in Table 1 may use manual tank gauging as the sole method of release detection in accordance with Section 15(a). All other tanks with a nominal capacity of 551 to 2,000 gallons may use manual tank gauging in place of inventory control.

(a) Manual Tank Gauging. Manual tank gauging shall meet the following requirements:

(i) Tank liquid level measurements shall be taken at the beginning and ending of the minimum test duration shown in Table 1 during which no liquid is added to or removed from the tank;

(ii) Level measurements shall be based on an average of two consecutive stick readings at both the beginning and end of the period;

(iii) The equipment used shall be capable of measuring the depth of the regulated substance over the full range of the UST's height to the nearest one-eighth of an inch;

(iv) A suspected release shall be declared and the requirements of Part E shall be followed if the variation between beginning and ending measurements exceeds the weekly or monthly standards in Table 1:

TABLE 1 MANUAL TANK GAUGING VARIATION STANDARDS
Nominal Tank Capacity		Weekly Standard (one test)	Monthly Standard (average of four tests)	Minimum Test Duration Hours*
	550 gallons or less	10 gallons	5 gallons	36
	551-1,000 gallons (when the tank diameter is 64")	9 gallons	4 gallons	44
	551-1,000 gallons (when the tank diameter is 48")	12 gallons	6 gallons	58
	551-1,000 gallons	13 gallons	7 gallons	36
	1,001-2,000 gallons	26 gallons	13 gallons	36

* Nothing can be added to or removed from the UST for the duration of the test.

(b) Other Release Detection Methods. Owners and/or operators of petroleum USTs with a capacity of 2,000 gallons or less may also use any of the release detection methods listed in Section 16(a) through (j).

Notes

020-1 Wyo. Code R. § 1-15

Adopted, Eff. 6/29/2018.