NOTE: Function tests are not required on confirmed "safe suction" dispensing lines.
When permanently closing a tank by filling with inert solid material, the tank may not be filled until a closure report is approved by the department. The tank must be filled within 30 days after department approval. The owner and operator must notify the department within 15 days after filling the tank with inert solid material.
NOTE: The following cleaning and closure procedures may be used to comply with subrule 135.15(2):
* American Petroleum Institute Recommended Practice RP 1604, "Closure of Underground Petroleum Storage Tanks";
* American Petroleum Institute Standard 2015, "Safe Entry and Cleaning of Petroleum Storage Tanks, Planning and Managing Tank Entry From Decommissioning Through Recommissioning";
* American Petroleum Institute Recommended Practice 2016, "Guidelines and Procedures for Entering and Cleaning Petroleum Storage Tanks";
* American Petroleum Institute Recommended Practice RP 1631, "Interior Lining and Periodic Inspection of Underground Storage Tanks," may be used as guidance for compliance with this subrule;
* National Fire Protection Association Standard 326, "Standard for the Safeguarding of Tanks and Containers for Entry, Cleaning, or Repair"; and
* National Institute for Occupational Safety and Health Publication 80-106, "Criteria for a Recommended Standard...Working in Confined Space" may be used as guidance for conducting safe closure procedures at some hazardous substance tanks.
At UST sites with a history of petroleum storage, soil and groundwater samples shall in every case be analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) with each compound reported separately in accordance with rule 567-135.16 (455B). If there has been a history or suspected history of petroleum storage other than gasoline or gasoline blends (i.e., all grades of diesel fuels, fuel oil, kerosene, oil and mineral spirits), or such storage history is unknown or uncertain, soil and groundwater samples shall also be analyzed for total extractable hydrocarbons in accordance with rule 567-135.16 (455B).
All such samples shall be collected separately and shipped to a laboratory certified under 567-Chapter 83 within 72 hours of collection. Samples shall be refrigerated and protected from freezing during shipment to the laboratory.
When a UST is removed from an area of confirmed contamination, the department may waive closure sampling if written documentation is submitted with the closure notification. Documentation should include laboratory analytical reports and a site map showing tank and piping locations along with contamination plume and sampling locations.
If, however, the first saturated groundwater zone is not encountered within 10 feet below the lowest elevation of the tank excavation, the requirement for groundwater sampling shall not apply unless:
If sands or other highly permeable soils are encountered, alternative sampling methods may be required.
If contamination is suspected or found in any area within the excavation (i.e., sidewall or bottom), a soil sample must be taken at that location.
The numbers of samples required for tanks are as follows:
Nominal Tank Capacity (gallons) | Number of Samples | Location on Centerline |
1,000 or less | 1 | center of tank |
1,001 - 8,000 | 2 | 1/3 from ends |
8,001 - 30,000 | 3 | 5 feet from ends and at center of tank |
30,001 - 40,000 | 4 | 5 and 15 feet from ends |
40,001 and more | 5 | 5 and 15 feet from ends and at center of tank |
The minimum numbers of soil borings and samples required are as follows:
Nominal Tank Capacity (gallons) | Number of Samples | Location of Samples |
6,000 or less | 4 | 1 each end and each side |
6,001 - 12,000 | 6 | 1 each end and 2 each side |
12,001 or more | 8 | 1 each end and 3 each side |
Identification of free product requires immediate response in accordance with 135.7(5). If contamination appears extensive or the groundwater is known to be contaminated, a full assessment of the contamination will be required. When a full assessment is required or anticipated, collection of the required closure samples is not required. If contamination appears limited to soils, overexcavation of the contaminated soils in accordance with 135.15(4) may be allowed at the time of closure.
Owners and operators or other interested parties are not required to submit documentation that USTs meet the exemption conditions and may rely on this subrule as guidance. However, should a question arise as to whether USTs meet the exemption, or owners and operators or other interested parties request acknowledgment by the department that USTs are exempt, they must submit an affidavit on a form provided by the department. The affiant must certify that based on a reasonable investigation and to the best of the affiant's knowledge, the USTs were taken out of operation prior to January 1, 1974, the USTs have not contained a regulated substance since January 1, 1974, and the USTs do not currently contain an accumulation of regulated substances.
If the department has a reasonable basis to suspect a release has occurred, the release investigation and confirmation steps of rule 567-135.6 (455B) and the corrective action requirements as provided in rules 567-135.7 (455B) through 567-135.12 (455B) shall apply.
Iowa Admin. Code r. 567-135.15