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As an interim measure (IM), up to 100 cubic yards of surface soils contaminated with suspected nickel penetrate will excavated and disposed of in accordance with all applicable regulations. All wastes are assumed to be Class I or Class II non-hazardous wastes, and will not require any further additional handling or stabilization. However, if wastes are determined to be hazardous, then management activities will be in accordance with Sections V and VI of the Waste Analysis Plan (WAP), Addendum 2 specific to delivery order RL33 Sampling and Analysis Plan.

Prior knowledge of the waste stream may indicate that material from AOC 50 may be considered characteristically hazardous due to elevated metallic concentrations. Stabilized and non-stabilized over-excavated soils removed from AOC 50 will be tested for inorganic compounds according to the methodology and parameters listed in this document. Although nickel is primary suspected contaminant, other metallic constituents may include hazardous levels of barium, cadmium, chromium, lead, as well as zinc. Therefore, contaminated soils may contain contaminant concentration levels for which treatment standards might be applicable.

3.1 - Waste Segregation and Storage

Knowledge of previous waste management practices indicates that material at AOC 50 may be characterized as a mix of potential hazardous and non-hazardous waste. The primary contaminant of concern is suspected to be is nickel penetrate. Prior to the mobilization of the remediation contractor, one sample will be collected of the spent penetrate to characterize the nature of the material. This will help identify the if waste is characteristically hazardous, and whether the SOW will need modification to handle the hazardous IDW.

Prior to the excavation of soils, all visible fragments of suspected nickel penetrate will be collected and segregated into 55-gallon containers. It is anticipated that freestanding metallic fragments can be collected either manually, or discretely with the appropriate machinery. The remaining soils to be excavated will be removed by heavy machinery, and placed into rolloff-type boxes.

All wastes will be stored on-site until the waste characteristics can be determined and the final disposition can be arranged. If the metallic solids have been pre-determined to be hazardous wastes, those solids will be relocated to Building 86 pending fnal disposition. It is expected that the quantity of hazardous residuum would be low, and can be contained within 55-gallon drums. This small quantity will be disposed of as a hazardous material to an appropriate facility.

3.2 - Hazardous Waste Stabilization

As required by a contract modification, hazardous waste material will be stabilized with an approximate 14% (by weight) portland cement mixture prior to disposal. The standard operating procedures for waste stabilization are provided by the subcontractor in the Brief Work Plan (Eagle Construction and Environmental Services, Inc., 1997). Portland cement has been identified as the most appropriate solidification/stabilization (S/S) agent due to its ability to reduce leaching, its structural integrity, and material efficiency.

Portland cement is proven to significantly reduce the leachability of metals, in particular lead. A study prepared for the Environmental Protection Agency (EPA) performed a comparison of different techniques for the S/S of contaminated soils. This study concluded that when the appropriate immobilization agent is used, "S/S can reduce the leachability of many metals to near the normal detection limits�as determined by the [toxicity characteristic leaching procedure] TCLP" (Acurex, Corp, 1989). An appropriate binding agent is chosen such that the hazardous waste and does not adversely affect setting, curing, or permanence of the matrix. Contaminants that interfere with any of these processes are considered contaminant restrictions. The S/S comparative study finds that there are very few contaminant restrictions for portland cement.

When compared to the other major S/S media, such as lime kiln dust and equal weight lime and fly ash, portland cement also tends to produce the most robust matrix while maintaining a high soil to cement ratio. The material strength of the resultant matrix is maintained for a variety of contaminants with differing water contents even at a high soil to cement ratio. Therefore, large quantities of soils and sludges may be solidified with little cement, while maintaining structural integrity.

Portland cement is the most widely used S/S agent used, and is especially suitable for immobilizing metals contaminated soils and sludges due to the pH of the cement mixture. As concluded by the EPA study, "The portland cement proved to be a superior binder by many criteria and appears to be the binder of choice of the [ones] evaluated here".

3.3 - Parameters and Test Methods

As previously mentioned, the suspected contaminant of concern at AOC 50 is nickel penetrate. Analytical methods defined in Table 6 below will be used for the detection of this constituent. If the laboratory results from these analyses indicate that the soils are hazardous, those soils will be stabilized upon an SOW modification. If the soils are not hazardous, they will be disposed of as specified in the FSP. If stabilization is necessary, leachable constituents from waste or other materials will be a concern for the stabilized soils. These soils will be sampled by extraction, using method SW1311, as required by 268.7(a). These analytical techniques will follow procedures described in "Test Methods for Evaluating Solid Waste", U.S. EPA, SW-846 and the AFCEE QAPP.

3.4 - Sampling Frequency

Over-excavated soils which are intended for off-site disposal and are not stabilized will be sampled at a maximum frequency of one per 50 cubic yards, or in an amount required by the landfill facility. Soils that are stabilized will be sampled at a frequency of one per batch, approximately 20 cubic yards per batch to verify the success of the treatment.

3.5 - Special Procedural Requirements

The stabilization treatment will be performed on applicable and appropriate soils in batch treatment operations. The treated waste streams will be stored on site until confirmation is received that the appropriate LDR treatment standards have been meet. In accordance with LDR regulations (40 CFR Part 268), all treated waste shipped off-site will be analyzed, to determine whether the waste meets applicable LDR treatment standards contained in 40 CFR ��268.41-48. All waste destined for off-site disposal will be tested for applicable parameters in 40 CFR ��268.41-48 to ensure that accurate LDR notifications and certifications are provided. All analytical results completed in support of LDR requirements will be retained within the facility operating record.

Wastes resulting from stabilization operations that exceed applicable LDR treatment standards will be either retreated until the LDR standards are met or sent off-site for further treatment to attain the numeric LDR standards. LDR notifications will be supplied with the shipment of waste with the information required under 40 CFR 268.7. In addition to the LDR notification, any additional data on the generated wastes will be provided to the subsequent permitted treatment, storage, or disposal facility (TSDF).

The treated waste can be disposed of in a Subtitle D landfill if they are determined after treatment to have attained the LDR treatment standards and no longer exhibit any hazardous waste characteristics.

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