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17. Section 3.2.2.3 indicates that the factors contributing to the IRM injection well <br /> malfunctioning must be identified. The outcome of this study could impact the type of <br /> system chosen to return the treated water to the aquifer. <br /> This issue may be included as an injection well design data gap. Please <br /> address this more clearly in Section 2.3.2. <br /> Similarly, this issue should be reiterated in Section 2.3.3. This is similar to the <br /> concern identified in Section 2.4.2.5 on chemical and biological issues related <br /> to spreading basins and infiltration galleries. <br /> 18. Section 3.2.2.3 states that "The IRM injection wells have been inoperable due to <br /> chemical scaling, biofouling and, possibly, other unidentified contributing factors ..." <br /> Section 3.2.2.9 states that the Langeher Index of the groundwater entering the <br /> treatment plant will be calculated to assess the need for pretreatment of the <br /> groundwater. If the treated groundwater is to be disposed of in injection wells, the <br /> following is recommended: <br /> The Langeher Index of the air stripper effluent should be calculated to determine <br /> if this water will require additional treatment to prevent scaling problems in the <br /> injection wells. <br /> The potential for injection well plugging by iron and manganese compounds <br /> should be evaluated. <br /> The potential for biofouhng in the injection wells should be evaluated. <br /> The potential for plugging by suspended solids should be evaluated. <br /> The ground-water treatment scheme may need to be revised depending upon the <br /> results of the above evaluations. <br /> 19. Section 5.1.2.3, regarding ARARs, includes text which refers to "closure or discharge <br /> of dredged or fill material." It is not clear to EPA why this text appears in the <br /> document. Further, it is not clear why this document attempts to provide narrative to <br /> the ROD's ARARs Tables. In the development of the ROD, the FFA parties agreed to <br /> delete that text which attempted to reiterate the requirements presented in the ARARs <br /> Tables. <br /> Please justify the inclusion of this text in this document or modify this section to <br /> be consistent with the approach taken in the ROD. <br /> 20. Section 5.1.2.11 erroneously refers to "injection wells and/or surface impoundments." <br /> EPA111JAN94 5/6 <br />