BIOREMEDIATION OF EXCAVATED PETROLEUM
The DEQ provides this information to facilitate approval of workplans for one-time biotreatment of petroleum contaminated soils using conventional landfarming techniques. Bioremediation will only be approved when appropriate controls are in place to protect the underlying soil, groundwater and ambient air.
The cost of hauling and disposing is often less than building and maintaining an adequate treatment cell. If biotreatment is chosen as the remediation alternative, this must be an active process with appropriate and timely aeration and watering as well as possibly additional amendments such as fertilizer or microbes. The default cleanup goal for the soils should be 50 mg/kg TPH. Levels higher than 50 mg/kg may be approved on a case by case basis depending on the proposed use of the soils after remediation, and the presence of adequate controls (for example, a fenced site on property where public access is restricted- an airport or interstate highway median- may have higher levels than 50 mg/kg allowed based on the potential exposures at that site). It is important to evaluate costs for different remedial options. Bioremediation is not a passive treatment and requires capital as well as operational and on-going analytical costs. We encourage careful comparison of biotreatment costs to conventional landfill disposal costs. Disposal in a landfill is often more economical, depending upon the volume of soil and the level of contamination.
It is unlawful for any person to cause pollution of the waters of the state or to place or cause to be placed any wastes in a location where they are likely to cause pollution of any air, land or waters of the state. Any such action is a public nuisance. If the DEQ determines there is such pollution, an order can be entered requiring such manner of treatment or disposition of the polluting material as may be necessary to prevent further pollution. For voluntary clean-up activities of petroleum contaminated soils, the DEQ and the remediator can enter into a consent order, which contains the terms of the remediation.
The terms of the consent order require submittal of a workplan for approval by the DEQ. The workplan sets forth design, construction and operational standards. Failure to follow an approved workplan could be a violation of the order and subject to enforcement actions under the Environmental Quality Code. (Specifically: 27A O.S. § 2-6-105(A), 27A O.S. § 2-6-105(B) and 27A O.S. § 2-3-506(B))
Risk-based Decision Making
Decision-making regarding appropriate methods of dealing with petroleum contaminated soil will be based on protection of human health and the environment, both present and future. The responsible party may choose disposal or biotreatment based on cost considerations, with the understanding that the Department’s goal is to achieve protection in both an economical and expedient manner. Reuse of soils remediated to higher levels than those detailed in the Remedial Options Section must be approved on a site-specific basis.
Contaminated soil often is excavated from a site prior to testing. Regardless of where it is staged, the material must be placed on plastic (10-mil or thicker), bermed, and covered with 10- mil or thicker plastic to prevent run-off and vapors from forming without appropriate controls. Staging is only temporary until disposal is approved or a workplan for bioremediation is approved by the Department.
Sampling and Analysis
Petroleum contaminated soil should be adequately characterized. If information is available as to the type of spill then certain testing methods may be more appropriate than others. Gasoline may be characterized with Total Petroleum Hydrocarbon (TPH)/Gasoline Range Organics (GRO) and Benzene, Ethylbenzene, Toluene and Xylenes (BTEX), EPA Method 8020/8015(Modified). If the release is old, or the exact nature of the materials released is unknown, then Volatile Organic Compounds (VOCs) and Semi-volatile Organic Compounds (SVOCs) as well as the hazardous metals may need to be sampled and analyzed. Known diesel contamination may be analyzed with the Diesel Range Organics (DRO) portion of EPA Method 8015(Modified). (NOTE: Generally, composite samples should be collected for every 200 cubic yards of material. If testing is done on soil still in place, discrete samples should be collected every 20 linear feet, or according to approved grid.)
Biotreatment proposals must be accompanied by a workplan that includes all of the information on the attached WORKPLAN CHECKLIST. The workplan may be prepared while soil testing is still being carried out, but appropriate analyses must accompany the workplan when it is submitted to the department. The following subjects should be addressed:
Location of proposed treatment area
The following checklist may be used to determine if the required elements of the workplan are addressed:
1.________ Consent Agreement signed by responsible party and DEQ.
2.________ Characterization of soil, including laboratory data, QA/QC Plans.
3. _________ Location of proposed bioremediation site, including flood plain maps.
4. _________ Ownership verification for proposed site.
5. _________ Groundwater maps, depth to groundwater, distance to surface water, floodplain maps.
6. _________ Location of water wells within 500 feet; nearest public water supply wells.
7. _________ Volume of material to be treated.
8. _________ Design plans including liner construction.
9. ________ Control of public access.
10. ________ Air Quality Applicability Determination (if volatiles present) [405-702-4100]
11. ________ Schedule for Operations, including tilling, irrigating, nutrient addition
12. ________ Storm water control – How will storm water be handled? How will cell be dewatered if excess rain occurs?
13. ________ Proposed disposition of soil after remediation.