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Notice Proposing To Reissue a Variance From Land Disposal Restrictions Granted to Exxon Mobil Corporation, Billings, MT

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Environmental Protection Agency (EPA).


Notice of proposed decision.


This is a notice to interested parties that EPA is proposing to reissue a no-migration variance for land disposal of hazardous waste to Exxon Mobil Refining & Supply Company Billings Refinery (“Exxon”), a division of Exxon Mobil Corporation, formerly known as Exxon Company U.S.A. Authority for the decision has been delegated to the EPA Regional Administrator. The original July 27, 1993 variance (58 FR 40134) approved under Resource Conservation and Recovery Act regulations (40 CFR 268.6) allowed Exxon to place certain untreated hazardous wastes subject to the RCRA land disposal restrictions (42 U.S.C. 36901 et. seq.) at their Billings (Montana) refinery South Land Treatment Unit (SLTU). In the original variance, the unit was referred to as the New South Land Treatment Unit. Exxon submitted a request to EPA on March 24, 1998 for renewal of this no-migration variance in conjunction with their State of Montana hazardous waste permit reissuance. Exxon also petitioned to amend the variance by adding the newly listed hazardous waste, Petroleum Refinery Primary Oil/Water/Solids Separation Sludge (EPA hazardous waste code F037). The proposed variance reissuance includes the F037 waste stream, “Primary Sludge,” generated at the Exxon Billings Refinery.

In granting the original variance, we concluded that Exxon demonstrated to a reasonable degree of certainty that hazardous constituents would not migrate out of the land treatment facility at levels exceeding no-migration criteria for as long as the wastes remain hazardous. We have reviewed the SLTU monitoring data submitted by Exxon for the period the variance was in effect along with other relevant information, and it still supports our original conclusion on Exxon's no-migration demonstration. We also concluded that Exxon adequately met the conditions of the original variance, which were included to ensure compliance with their no-migration demonstration.

The present proposal considered how the terms of the original variance were affected by certain changes in waste application techniques and closure requirements incorporated into the recently issued Montana hazardous waste permit (No. MTHWP-99-02) and one failure to correctly manage a waste stream whose hazardous status had changed during the term of the original variance. We concluded that these factors did not materially affect the overall demonstration of no-migration. The proposed variance reissuance again includes specific conditions tailored to reflect additions of a newly hazardous waste stream (F037), modifications to how no-migration standards apply to specific SLTU monitoring systems, additional monitoring requirements, and improvements to the Exxon waste application tracking system. Certain conditions of the original variance are also included. The full set of variance conditions are presented below.

RCRA regulations require that we provide for public comment on a proposed no-migration variance decision. In addition to seeking written comments through this notice, we have elected to hold a public hearing in Billings, Montana to gather comment on this proposed decision from the local citizens near Exxon's land treatment facility and other interested parties. All comments received will be entered into the public record for this decision making process. Details appear below in the DATES section of this document. A final decision will be made by EPA after considering and responding to public comments. We will then publish a notice in the Federal Register of our decision on the reissuance of the variance and the addition of Primary Sludge (F037). Copies of the statement of basis for the proposed decision are available in the record for today's document and can be requested from Tina Diebold at the address or telephone number listed below.


Comments on the proposed decision must be received on or before June 5, 2000. In addition to the written comments received at EPA's Montana Office, written and oral comments on the proposed decision also will be accepted by the Hearing Officer at the public hearing in Billings, Montana. The public hearing is scheduled for May 23, 2000 from 6 p.m. to 8:30 p.m.


Comments on the proposal should be sent to EPA at the following address: Tina Diebold, Mail Code 8MO, Montana Office, U.S. EPA Region VIII, 301 S. Park, Drawer 10096, Helena, Montana 59626-0096. The public hearing will be held at the Parmly Library at 510 North Broadway, Billings, Montana (large, open meeting room on third floor).

A copy of the record supporting this proposal is available to the public at the Parmly Library at 510 North Broadway, Billings, Montana, and is available for public review during regular library hours. Another copy of the record is available in Helena, Montana, at the EPA Region VIII, Montana Operations Office, Federal Building, 301 South Park. The public may make arrangements to view the documents in Helena by calling Tina Diebold at (406) 441-1130. The record is available for inspection in Helena from 8 a.m. to 4 p.m., Monday through Friday, except Federal holidays.

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Tina Diebold, Mail Code 8MO, Montana Office, U.S. EPA Region VIII, 301 S. Park, Drawer 10096, Helena, Montana 59626-0096, at (406) 441-1130.

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Wherever “we” is used throughout this document, it refers to EPA.

A. What Conditions and Reporting Requirements Are Proposed for the Exxon No-Migration Variance Reissuance?

As part of this reissuance of the no-migration variance and addition of Primary Sludge (F037), we propose that Exxon comply with the following conditions. These conditions are in addition to those required of Exxon under 40 CFR 268.6. EPA would directly enforce these conditions, and a violation of a condition would constitute a violation of the RCRA land disposal restrictions. Unless otherwise notified by EPA, Exxon shall provide the required notices and reports to the EPA Region VIII Montana Operations Office, Federal Building, 301 South Park, Drawer 10096, Helena, MT, 59626. Exxon shall provide a separate copy to the State of Montana of any report or notice required by the variance if the information is not combined with the reports required under its Montana hazardous waste permit. Exxon shall provide copies to the State at the address specified for its Montana hazardous waste permit reporting requirements.

We interpret the no-migration standard to mean that concentrations of hazardous constituents cannot exceed EPA-approved health-based levels in any environmental medium at the boundary of the land disposal unit. Hazardous constituent levels exceeding those presented in Table 1 of this document constitute migration into ground water at the unit boundary, as measured by soil-pore liquid and below Start Printed Page 21420treatment zone (BTZ) soil-core monitoring, and as measured by ground water monitoring under the Exxon Montana hazardous waste permit and as defined below. In the event that Exxon should detect other RCRA hazardous constituents (defined in 40 CFR part 261, appendix VIII) above health-based levels, this event would also be subject to the notification requirements in 40 CFR 268.6(f). Definitions of the unit boundaries (i.e., points of compliance for no-migration purposes) remain the same as in the original variance (57 FR 10478). Metals levels in the SLTU zone of incorporation (ZOI) soils (the top 23 centimeters of the treatment zone) exceeding the limits listed in item 1.a. below are also evidence of a no-migration standard exceedance.

In accordance with 40 CFR 268.6(k), the proposed variance will be valid for up to ten years from the date of EPA approval of the petition, but no longer than the term of Exxon's Montana hazardous waste permit, unless the permit is renewed or reissued.

1. Montana Hazardous Waste Permit Conditions

Exxon must comply with conditions of the Montana hazardous waste permit effective June 28, 1999 (No. MTHWP-99-02) regarding characterization of wastes disposed of at the SLTU, and monitoring of ground water, soil and soil-pore liquids at that unit. Exxon must provide the results of this characterization and monitoring to EPA on the same schedule as they are provided to the State of Montana under Exxon's Montana hazardous waste permit.

In addition, Exxon must follow the monitoring provisions below specific to this variance, which are intended to supplement the existing Montana hazardous waste permit conditions. Exxon may provide the information required as a condition of the variance to EPA in the annual reports required by its Montana hazardous waste permit. Exxon shall submit annual reports for the previous calendar year by April 30.

a. ZOI Metals Loading Limit

Exxon shall determine if any of the following risk limits have been exceeded when it evaluates the annual SLTU ZOI soil samples for the metals loading limits under its Montana hazardous waste permit: 31 mg/kg for antimony; 15 mg/kg for arsenic; 2 mg/kg for beryllium; 140 mg/kg for total chromium; 400 mg/kg for lead; and 7 mg/kg for mercury. In the event one or more of these criteria are exceeded, Exxon may only place wastes on the SLTU areas(s) for which the metals concentrations are less than or equal to the in-soil concentration limits. Exxon shall submit the analytical results and comparisons in an annual report to EPA. Exxon shall report exceedances of these limits to EPA within ten days of receiving the analytical results.

b. Soil-Pore Liquid Monitoring

Exxon shall evaluate the following metals as part of semi-annual SLTU soil-pore lysimeter monitoring requirements under the Montana hazardous waste permit: antimony, arsenic, barium, beryllium, cadmium, chromium, lead, mercury, nickel, selenium, vanadium, and zinc. Samples from each of the three SLTU lysimeters shall be .45-micron filtered prior to analysis for metals. SW-846 [1] or equivalent analytical methods shall be used which can provide reporting limits of .001 mg/l, except .0002 mg/l for mercury. Exxon shall attempt to collect sufficient sample volumes to meet these performance criteria, following the general analytical priority scheme in its Montana hazardous waste permit. Should sample volumes be insufficient, Exxon shall investigate collecting additional sample volumes in a reasonable time frame for metals analysis once the Montana hazardous waste permit conditions have been met. Additionally, analyses of soil-pore organic monitoring constituents shall meet the SW-846 estimated quantitation limits (EQL) specified for water samples in Exxon's Montana hazardous waste permit and as listed in Table 1, to the extent possible.

c. Soil-Pore Liquid Monitoring Evaluation and Reporting

Exxon shall compare the organic hazardous constituents and the metals results to the leachate soil-pore health-based standards identified in Table 1 below. Exxon shall submit the analytical results and comparisons including information on sample volumes collected, analytical methods used, and EQLs achieved for all sample constituents, in an annual report to EPA. Exxon shall report exceedances of these limits to EPA within ten days of receiving the analytical results. Exxon shall notify EPA and the State if sufficient sample volumes cannot be collected or EQLs cannot be achieved in any semi-annual sampling period.

d. BTZ Soil-Core Monitoring

When collecting the five (5) annual soil cores from the SLTU Below Treatment Zone (BTZ) as required by its Montana hazardous waste permit, Exxon shall also collect intermediate level treatment zone soil samples at three depth intervals of 2-2.5 feet below ground surface (bgs), 3-3.5 feet bgs, and 4-4.5 feet bgs and in the BTZ itself (5-5.5 feet bgs), sufficient for analyses of oil and grease and soil pH. Oil and grease and soil pH results shall be reported for the four depth intervals in each of the five soil core samples. Exxon shall use an oil and grease analytical method which can provide detection limits in the range of 10 to 100 mg/kg consistent with the Montana hazardous waste permit. Exxon also shall analyze any BTZ resamples required under the Montana hazardous waste permit for oil and grease and soil pH. Exxon shall submit the results of the annual BTZ sampling (including the pH and oil and grease results from the intermediate levels) in an annual report to EPA. Exxon shall submit the results of any resampling to EPA on the same schedule as provided to the State under Exxon's hazardous waste permit.

e. Evaluation of BTZ Soil-Core Monitoring

Analyses for organic monitoring constituents shall meet soil low-level required EQLs as specified in Exxon's Montana hazardous waste permit and as specified in Table 1 below. Exxon shall compare the results of BTZ soil samples with soil-core health-based standards identified in Table 1 of this document. Exxon shall submit the analytical results and comparisons in an annual report to EPA. Exxon shall report exceedances of these limits to EPA within ten days of receiving the analytical results. Start Printed Page 21421

Table 1.—Proposed Exxon No-Migration Variance Leachate and Soil-Core Standards

ConstituentsLeachate soil-pore standards (mg/l)Soil-core standards (mg/kg)
I. Volatiles:
Benzene.005 (EQL)—MCL.002 (EQL)
II. Semi-Volatiles:
Benzo(a)anthracene.0001 (EQL)—Risk.08 (EQL)
Benzo(b)fluoranthene.0001(EQL)—Risk.25 (EQL)
Chrysene.0012 (EQL)—Risk9.3
2,4-Dimethyl phenol.7—Risk.43
Cresol (o-)1.8—Risk.69
III. Metals:
Antimony.006—MCLNot proposed
Arsenic.05—MCL  Do.
Barium2—MCL  Do.
Beryllium.004—MCL  Do.
Cadmium.005—MCL  Do.
Chromium.1—MCL  Do.
Lead.015—MCL  Do.
Mercury.002—MCL  Do.
Nickel.7—Risk  Do.
Zinc10—Risk  Do.
Selenium.05—MCL  Do.
Vanadium.24—Risk  Do.

An (EQL) indicates a risk-based standard lying below the expected low-level quantification limit for the routine analytical methods assumed from Exxon's Montana hazardous waste permit. Typical quantification limits would be: SW-846 Method 8260—.005 mg/l aqueous and .005 mg/kg clean soils and Method 8270—.01 mg/l aqueous and .33 mgl/kg clean soil. NS indicates no standard.

2. Annual Benzene Loading Limit

The total amount of benzene that may be disposed of at the SLTU may not exceed a cumulative mass loading of 49 Kg per calendar year. Exxon must determine the benzene content of each wastestream, including each load of Primary Sludge (F037) prior to placement at the land treatment unit. Representative samples of each wastestream must be analyzed for benzene as they are generated during the land application season in accordance with the promulgated edition of SW-846. The term “as generated” means each time the wastes are removed from the wastewater system, created through a spill, or a tank is cleaned out, and the wastes are taken or will be taken to the land treatment unit, which may be several times a year. A tracking system must be in place which continually estimates and updates the cumulative benzene waste loading during the operating season. Exxon must submit a summary of these waste analyses demonstrating its compliance with the loading limit to EPA in an annual report. When the 49 Kg benzene limit is reached, Exxon must not dispose of any additional waste containing detectable levels of benzene at the SLTU until the next calendar year. Exxon shall notify EPA when the 49 Kg limit is reached within ten days of receiving the analytical results.

3. Waste Characterization

Exxon must identify in the annual report to EPA the following additional information for each applied waste at the SLTU: the location of waste generation (e.g., Tank 17 sewer, Tank 108 contaminated soil); analytical results of waste determination for any wastes for which the hazardous status was not known when it was generated, mass of waste; application date(s); the hazardous waste code (if any); and the matrix (e.g., soil or sludge). In the report, Exxon must distinguish between the F037 waste generated from the sewer (e.g., “F037 sewer sludge”) and the F037 waste generated from the Alkyllation Unit Neutralization Basins (e.g., “F037 lime sludge”). In the annual report, Exxon must also include the total quantity of waste applied at the SLTU during the last operating season and a break down of the total quantity of hazardous and of non-hazardous waste.

4. Application of F037 Sewer Sludge

Exxon's application of Primary Sludge generated from the sewer system (F037 sewer sludge) to the SLTU is restricted to times when Exxon also applies API Separator Sludge (K051). Exxon must combine the F037 sewer sludge with the API Separator Sludge prior to or during application at the SLTU. Exxon shall incorporate this condition in its waste tracking system to ensure that any time F037 sewer sludge is cleared for application to the SLTU, it is accompanied by K051 waste.

5. Application of F037 Lime Sludge

Exxon's application of Primary Sludge generated from the Alkyllation Unit Neutralization Basin (F037 lime sludge) to the SLTU is limited to when it has determined pH adjustment of the ZOI Start Printed Page 21422soils is needed according to the applicable criteria and methods identified in its Montana hazardous waste permit. For the years in which Exxon uses F037 lime sludge to adjust the pH of the ZOI soils at the SLTU, Exxon must submit to EPA the following information in the annual report: pH of the F037 lime sludge applied to the SLTU, and the other measurements and tests used to determine the need for pH adjustment as well as the quantity of F037 lime sludge applied and the quantity of any other substance (e.g., lime) used to adjust the pH of the ZOI soil at the SLTU.

6. Waste Tracking

As part of its waste tracking process, Exxon must confirm receipt of analytical results for any wastes for which the hazardous status is not currently known prior to application of the waste at the SLTU. Exxon must comply with its Montana hazardous waste permit conditions with regard to restrictions on the application of waste to the SLTU, such as any restrictions based on the pH of the waste.

7. Information Requests

Upon request by EPA, Exxon shall provide to the EPA within a reasonable time, any relevant information requested to determine compliance with the conditions of this variance.

8. Access

Exxon shall allow EPA, or authorized representatives, upon the presentation of credentials and other documents as may be required by law to: (a) inspect at reasonable times any records, facilities, equipment (including monitoring and control equipment), practices, or operations related to the disposal of restricted hazardous wastes at the SLTU; and (b) sample or monitor at reasonable times, for the purposes of assuring compliance with the conditions of this variance or to determine migration or as otherwise authorized by RCRA, any wastes intended or proposed for disposal at the SLTU and the soil, air, soil-pore liquids or ground water in or surrounding the SLTU.

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Dated: April 13, 2000.

Stephen S. Tuber,

Acting Regional Administrator, Region VIII.

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1.  These methods are found in the third edition of “Test Methods for Evaluating Solid Waste Physical/Chemical Methods,” EPA, SW-846, which is available from the Government Printing Office (GPO). This compendium of EPA test methods is commonly referred to as “SW-846” and we will use this term to refer to the compendium throughout this document.

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[FR Doc. 00-10039 Filed 4-20-00; 8:45 am]