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<br /> <br />London Mountain Clean Up <br />July 2025 D-3 <br /> <br /> <br /> Pile Quantification & Qualification <br />The extents of each pile will be determined prior to excavation. <br />1) Determine pile volume, horizontal footprint, and underlying natural grade. <br />2) Collect one sample per 10,000 tons of identified material for lab testing <br />a. Test samples for ABA and SPLP <br />b. First sample should be taken at a depth of at least 2-ft within the pile. <br />c. Multiple samples should separated by at least 2-ft of distance. <br />d. Material that has an ABA > 20 will be considered Non-Potentially Acid Forming. Material <br />that tests with an ABA < 20 will be considered Potentially Acid Forming. <br />3) Produce short report of material quantity and quality and keep for records and for regulators <br /> Excavation Procedures <br />1) Prior to any material excavation, sediment control will be established around the perimeter of <br />the pile. <br />2) Uphill of the pile a runoff diversion structure will be installed. This structure may be a ditch or <br />berm. Runoff diversion structures will be capable of diverting the 10-YR 24-HR event around the <br />waste pile. Exhibit G contains a discussion of diversion structures. <br />3) Wattles or similar sediment control structures will be placed around the downhill perimeter of the <br />waste pile area. <br />4) Up to two entry/exit points may exist within the sediment control perimeter. <br />a. Entry/exits will maintain sediment containment by containing either a runoff control ditch <br />or runoff control berm at least 2-ft in total depth that diverts runoff away from the <br />entry/exit. <br />5) A general stormwater management plan will be maintained for all waste pile excavations. <br />6) A CDPHE stormwater discharge permit will be secured for each applicable pile or set of piles as <br />needed. <br />7) Excavation of waste piles will typically be conducted from the top down, removing material in <br />vertical slices to minimize the area of disturbed pile at any given time. See Map C-2 for an <br />example. <br /> Material handling <br />1) All material is to be excavated from the pile area to at least 6-inches below the natural grade or <br />bedrock depth, whichever is less.