MODOC COUNTY AIR POLLUTION CONTROL DISTRICT

RULE 8.2 - AERATION OF CONTAMINATED SOIL AND REMOVAL OF UNDERGROUND STORAGE TANKS
(Amended May 1, 1989)

A. Purpose
To limit the emission of organic compounds from underground storage tanks and contaminated soil.

B. Definitions

1. Active Storage Pile : A pile of contaminated soil to which soil is currently being added or from which soil is currently being removed. Activity must have occurred or be anticipated to occur within one hour to be current.
2. Aeration : Exposure of excavated contaminated soil to the air.
3. Aeration Depth : The smaller of the following: the actual average depth of contaminated soil; or 6 inches multiplied by the daily frequency with which soil is turned. The exposed surface area includes the pile of excavated soil unless the pile is covered.
4. Aeration Volume : The volume of soil being aerated shall be calculated as follows: the exposed surface area in square feet shall be multiplied by the aeration depth.
5. Contaminated Soil : Soil which has an organic content exceeding 50 ppm (weight).
6. Organic Compound : Any compound of carbon, excluding methane, carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates and ammonium carbonate.
7. Organic Content : The concentration of organic compounds measured in the composite sample collected and analyzed using the procedures specified by this rule.
8. Vapor Free : The process of purging gases from a tank using dry ice to replace organic vapors with an inert atmosphere.
9. Ventilation : The process of purging gases from a tank by blowing or drawing another gas through the tank.

C. Notification
Five days prior to underground tank removal or excavation of contaminated soil, the person responsible shall give written notification to the District.

D. Underground Storage Tank Removal
Any person wishing to permanently decommission an underground storage tank which previously contained organic compounds shall follow the following procedure:

1. All piping shall be drained and flushed into the tank or other container.
2. All liquids and sludges shall be removed, to the extent possible, from the tank. It may be necessary to use a hand pump to remove the bottom few inches of product.
3. Vapors shall be removed from the tank by either vapor freeing or ventilation.
4. No person shall ventilate or vapor free a tank containing more than 0.001 gallons of liquid organic compounds per gallon of tank capacity unless emissions of organic compounds to the atmosphere are controlled by equipment or control schemes which demonstrate a combined collection and destruction efficiency of 90 percent by weight. All control equipment and control schemes subject to this section shall have written District approval prior to operation.

E. Excavation of Contaminated Soil
The person responsible for aeration of any contaminated soil shall provide the District with the following information no less than 24 hours prior to the spreading or heating of any contaminated soil:

1. The maximum total quantity of soil to be aerated.
2. The maximum quantity of soil to be aerated per day.
3. The maximum degree of contamination.
4. The chemical composition of contaminating organic compounds (e.g., benzene, methylene chloride, etc.).
5. A description of the basis from which these estimates were derived (soil analysis, Soil Vapor Contamination Assessment, etc.).

The District shall be notified within 24 hours if any of the parameters change. During excavation and aeration, daily records shall be kept of the total quantity of soil and the organic content of soil that is aerated each day.

F. Uncontrolled Aeration
A person shall not aerate contaminated soil at a rate in excess of that specified in Table I for the degree of organic content. The limitations in Table I apply to the entire facility, and indicate the volume of contaminated soil that may be added, on any one day, to soil that is already aerating.

Table I
Allowable Rate of Uncontrolled Aeration

G. Controlled Aeration
Soil may be aerated at rates exceeding the limitations of Table I provided emissions of organic compounds to the atmosphere are controlled by equipment or control schemes which demonstrate a combined collection and destruction efficiency of 90 percent by weight. All control equipment and control schemes subject to this section shall have written District approval prior to operation.

H. Storage Piles
Contaminated soil which is not being aerated shall be covered except when soil is being added or removed. No more than 10 percent of the storage pile or 20 cubic yards may be uncovered at any time without prior consent of the Control Officer. Any uncovered contaminated soil will be considered to be aerated. The soil may be covered with a layer of uncontaminated soil no less than six inches deep or it may be covered with a tarp or other covering, provided no head space where vapors may accumulate is formed.

I. Exemptions

1. Storage Piles: Calculations of aeration volume shall not include storage piles that are covered nor shall they include active storage piles.
2. Excavated Hole: The exposed surface of an excavated hole shall not be included in calculations of aerated volume.
3. Sampling: Contaminated soil exposed for the sole purpose of sampling shall not be considered to be aerated. No more than 10 percent of the contaminated soil or 20 cubic yards may be exposed at any time without prior consent of the Control Officer. Removal of soil for sampling shall not qualify a pile as "active."
4. Non-volatile Hydrocarbons: The requirements of this rule shall not apply if the only soil contamination is by a known organic chemical or petroleum liquid, and that chemical or liquid has an initial boiling point of 302°F or higher, provided that the soil is not heated.

J. Soil Sampling
One composite sample shall be collected and analyzed for every 50 cubic yards of excavated contaminated soil to be aerated. At least one composite sample shall be collected from each inactive, uncovered storage pile within 24 hours of excavation. Samples are not required if the soil is uncontaminated.

1. A composite sample shall consist of one sample taken from the center of each of 4 equal sectors of the area required to be sampled using the procedures described below unless other methods are approved by the Control Officer.
2. Samples shall be taken from at least three inches below the surface of the pile using a driven-tube type sampler, capped and sealed with inert materials, and extruded in the lab in order to reduce the loss of volatile materials or by using a clean brass tube (at least three inches long) driven into the soil with a suitable instrument. The ends of the brass tube shall then be covered with aluminum foil, then plastic end caps, and finally wrapped with a suitable tape. The samples shall then be immediately placed on ice, or dry ice, for transport to a laboratory.

K. Measurement of Organic Content
Organic content of soil shall be determined by the EPA Reference Method 8010 or 8015, Regional Water Quality Control Board's Revised Analytical Methods, Attachment 2, 11/8/85, or other methods approved by the Control Officer.