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August 31, 2010 <br />Mr. Ben Frei <br />Certificate of Designation Application for Frei-Henderson Inert Landfill <br />Completeness Review Determination: Complete <br />Page 4 <br />level data at the site. The DOP must address current groundwater dewatering activities, and <br />future dewatering plans, and how the dewatering activities will impact the hydrogeology. The <br />DOP must assess and address the potential for adverse impacts of filling activities on the <br />hydrogeology (i.e., Will the filling of inert material cause changes to groundwater flow patterns <br />and/or groundwater levels that could adversely impact surrounding properties?) <br />9. Section 4.1- Design Concepts: Section 4.1 indicates that the applicant proposes to place coal <br />ash at least 15 feet below the top of the final grades. If the applicant is successful in <br />demonstrating that coal ash can be used beneficially at the site, the Division will not allow <br />.placement of ash-containing material below-the groundwater table. Furthermore the DOP <br />must incorporate a buffer zone into the design to insure that ash-containing material remains <br />above the highest historical and/or anticipated groundwater level. <br />10. Section 4.2 - Excavation Plan: The DOP :must include a drawing that shows base-grade <br />contours prior to landfilling. Details of the compacted clay liner construction must be included <br />in the DOP. The DOP must include a copy of the "quality control plan " that is referenced in <br />Section 4.2 (see Comment #11). <br />11. Section 4.3 - Final Grades: The proposed final cover does not satisfy the requirements set <br />forth in Sections 3.5.2 and 3.5.3 of the Solid Waste Regulations. The Division requires final <br />landfill side-slopes to be no steeper than 25% (4H:1 V). Variations from other requirements in <br />Sections 3.5.2 and 3.5.3 of the Solid Waste :Regulations may be approved by the Division if the <br />adequacy of the proposed variance can be satisfactorily demonstrated through the waiver <br />process as described in Section 1.5 of the Solid Waste Regulations. Section 4.3 of the DOP <br />indicates that the final grades are proposed to be approximately 2%; whereas, Sheet Number 3 <br />of 3 shows proposed final grades of 1.5%. This discrepancy must be corrected. <br />Pursuant to the requirements in Section 3.3.3 of the Solid Waste Regulations a Construction <br />Quality Assurance/Quality Control Plan ("CQA/QCP") for all engineered features, which <br />would include final cover, must be prepared and approved by the Division prior to construction. <br />In preparing the CQA/QCP, the Division recommends using the testing frequencies and <br />-- -_-= -methodologies outlined in_th_Q_Divisiotj s_recently_ finalized guidance document for preparing <br />Quality Assurance/Quality Control Plans. While the guidance document does not specifically <br />address barrier layers in final covers, the testing frequencies and recommendations provided for <br />soil liners are appropriate for use in construction of a barrier layer in final cover. The guidance <br />document can be found at the following web site: http://www.cdphe.state.co.us/hm/ <br />engdesigngagc.pd£ <br />12. Section 4.4 - Slope Stability: Pursuant to the requirements in Section 3.5.2 of the Solid Waste <br />Regulations, the Division requires final slopes to be no steeper than 25% (4H:1 V). <br />13. Section 4.8 - Surface Water Control: Pursuant to the requirements in Sections 2.1.6, 2.5.7, <br />and 3.2.6 of the Solid Waste Regulations, facilities must design, construct, and maintain <br />stormwater run-on and run-off control systems. The DOP does not adequately address these