Underground Storage Tank Ordinance No. 4332
Attachment "B"

General Requirements for Underground Storage Tank Closure
(Removal or Closure in Place)


INSPECTIONS

The El Dorado County Environmental Management Department must be present to witness the extraction of the tank or closure in place, and all associated sampling activities. All inspections to witness UST closure activities must be scheduled with this agency a minimum of three days in advance. 

PERMITS

Underground storage tanks shall not be closed until a valid permit is issued by this agency. The Lake Tahoe basin shall require approval from the Tahoe Regional Planning Agency, as well, prior to any site work.

PROCEDURES

1. Preparation -
Prior to commencing any site work, all utility lines shall be located and properly marked.
Evacuate all fuel from the product lines for proper disposal. Ensure the tank system is properly prepared and free of appurtenances for removal. Use only non-sparking tools for this work.

2. Tank Cleaning -

  • Remove all product/waste from the bottom of the tank using an explosion proof pump that is properly grounded and bonded.
  • Ensure the tank is triple rinsed with an inert substance to remove the remaining sludge and/or scale from the interior of the tank.
  • The rinseate generated from the triple rinsing process must be handled in accordance with all applicable California hazardous waste disposal laws (i.e. disposed of at an authorized facility under proper manifest procedures by a transporter licensed in the State of California). The rinseate may be stored on site in an DOT approved 55 gallon drum for 7 days only.

3. Tank Inerting -
The inerting process replaces the oxygen and some of the flammable vapors within the tank with an inert gas, such as carbon dioxide, using the following procedure:

  • "Dry ice" shall be placed into a clean tank at a minimum ration of 3 pounds per 100 gallons of tank volume. All dry ice shall be evenly distributed over the tank bottom.
  • The goal of inerting is to reduce the level of oxygen in the tank to 10% or less. A meter reading of 6-7% oxygen is considered safe.
  • All openings on the tank shall then be tightly sealed, except for a 1/8 inch vent hole in a bung cap to allow for temperature expansion.

CAUTION: The atmosphere within the tank may reach the explosive limit again after initially being inerted. Therefore, an approved and properly calibrated hydrocarbon detector with an oxygen meter shall be utilized on site.

Closure-In Place Tanks - At this stage the tank system may be Closed-In-Place by completely filling it with an inert material, such as sand or concrete. Prior to Closure-In-Place activities, you must demonstrate that the tank system has not had an unauthorized release. This is accomplished by providing evidence of clean soil/ groundwater samples from soil borings collected beneath the tank system. Reference Attachments C, D, and the soil/groundwater sampling procedures identified below. All soil/groundwater sampling must be approved by this agency.

4. Tank Extraction -

  • Adequately remove the backfill from around the tank. All excavated materials suspected of any contamination, as detected by analysis, instrumentation, odor, or discoloration, shall be excavated and separately stockpiled on site in accordance with all erosion control guidelines identified in Attachment A.
  • Utilizing adequate heavy equipment and safety precautions, the tank shall then be removed from the excavation to a secure inspection area. Tanks should not be dragged at any time. A representative of this agency shall examine the tanks for signs of leakage and structural integrity.

5. Tank Disposal -
The California Department of Toxic Substances Control considers excavated tanks which held a hazardous material to be hazardous waste. Therefore, the handling and treating of these tanks must be in accordance with all applicable hazardous waste regulations (e.g. storage, transportation, manifesting, and treatment).

6. Soil Sampling -

  • All routine underground storage tank closures shall require analytical results of soil samples collected from the excavation in accordance with Attachment C.
  • The number and location of samples shall be performed in accordance with Attachment D or otherwise, depending on site conditions.
  • Samples are to be taken immediately after the removal of the tank using a clean stainless steel or brass cylinder that has been properly prepared by an approved party. The sampling cylinder must be at least three inches in length by one inch in diameter. If samples cannot be safely collected from within the excavation, a piece of heavy equipment may be utilized to obtain a segment from the native soil/backfill interface. About three inches of soil should be removed from the immediate surface area where the sample is to be taken. Thereafter, the cylinder shall be pounded into the soil with a wooden mallet. After sample collection is complete, each end of the cylinder shall be covered with teflon and then capped with a polyethylene lid, taped, and properly labeled. The cylinder containing the soil sample shall then be immediately placed into an ice chest containing ice and kept chilled until delivered to the laboratory for analysis.
  • Samples shall be analyzed, under strict chain-of-custody, by a laboratory certified by the California Department of Health Services.

7. Groundwater Sampling -

  • If groundwater is encountered in the excavation, both soil and groundwater samples shall be required. Groundwater samples shall be analyzed in accordance with Attachment C.
  • The number and location of samples shall be performed in accordance with Attachment D or otherwise, depending on site conditions.
  • The groundwater samples shall be collected in clean volatile organic analysis (VOA) vials. The liquid shall be completely filled to the top of the vial in such a manner that no air bubbles are entrapped. The VOA sample shall then be place into an ice chest containing ice and kept chilled until delivered to the laboratory for analysis.
  • Samples shall be analyzed, under strict chain-of -custody, by a laboratory certified by the California Department of Health Services.

8. Analytical Results -

Upon completion of sample analysis, all test results shall be submitted to this agency within seven (7) days. Any person, owner of real property or authorized agent shall immediately report, upon discovery or receipt of notification, any release or threatened release of a hazardous material to this agency. A complete written report shall be submitted to this agency within five (5) working days of discovery or receiving knowledge of a release.

9. Soil Disposal / Treatment -

  • All excavated material and soil suspected of contamination, as detected by analysis, instrumentation, odor, or discoloration, shall be excavated, separated, and stockpiles on the site in accordance with Attachment A.
  • All contaminated material and soil must be transported to an approved storage, disposal, or treatment facility in accordance with all Federal, State, and local requirements.
  • All contaminated material and soil containing a Total Petroleum Hydrocarbon (TPH) level equal to or greater than 1000 parts per million (ppm) shall be transported by a licensed hauler, under manifest, to an approved storage, disposal, or treatment facility in accordance with all Federal, State, and local requirements.

10.Soil / Groundwater Investigation -
A subsurface investigation to determine the vertical and lateral extent of possible petroleum contamination in the soil and/or groundwater at or in the vicinity of the site shall be required under the following conditions:

  • A tank failure is evident (e.g. a hole in the tank and/or piping is noted or saturated soil/groundwater conditions are observed).
  • Evidence of soil/groundwater contamination, verified by analytical results.

All interpretation of analytical results and protocol for soil/groundwater investigations will be conducted utilizing guidance documents issued by the State Water Resources Control Board, the Regional Water Quality Control Boards, and the California Department Toxic Substances Control.

(Revised 03-01-00)