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Ellicott Sand & Gravel LLC Schubert Ranch Sand Resource <br /> M-2018-063 August 26, 2019 <br /> BANK PROTECTION PLAN <br /> This bank protection plan is presented to explain the bank <br /> armoring on both side of the Black Squirrel Creek and the tops of <br /> the excavated slope that run parallel to the channel . This <br /> armoring is being proposed to keep the Black Squirrel Creek <br /> within in the historic banks so the excavated area will not <br /> capture if a epic flood event were to occur after reclamation is <br /> complete . The minimum width of the top of the armored banks will <br /> be 150 feet . <br /> We have followed the 2014 Urban Drainage and Flood Control <br /> District (UDFCD) Publication guideline document for planning and <br /> design of the armoring on the mining side bank and the bank <br /> armoring on the creek channel side . Ellicott Sand & Gravel LLC <br /> has no way or predict is or when a storm event could occur that <br /> would cause flooding outside the historic channel . The armor is <br /> intended to define the channel and protect the banks should a 100 <br /> year event occur after an area has been mined. All armoring done <br /> in or along the dry channel will be done outside the Ordinary <br /> Highwater Line (OHW) to avoid needing a U.S . Army Corps of <br /> Engineers permit . The existing OHW is shown on all map exhibits <br /> in the permit packet as an orange line . If this changes a mining <br /> advances around the permit area the armoring locations will <br /> change to meet the conditions at that time . The armoring will be <br /> covered with a 6 inch layer of growth medium and seeded with the <br /> approved seed mix <br /> We have no information on the flow velocities or volume of flows <br /> for a 100 year event in this stretch of Black Squirrel Creek. <br /> Black Squirrel Creek is a true ephemeral drainage where the only <br /> water that travels down the drainage is during isolated storm <br /> events that create mini floods . In most cases the OHW is 10 feet <br /> or less across . The 100-year Floodplain information provided by <br /> El Paso County has been added to all of the Map Exhibits in the <br /> Reclamation Packet and is shown as a blue line . <br /> There are general items that will be common to both armoring <br /> areas . In general, all armoring material will be recycled <br /> concrete and asphalt fragments that meet the definition of Inert <br /> Materials, there will be no exposed rebar in the concrete and it <br /> will be sized to D50 or greater. D50 is specified as 12 inch + <br /> with fines mixed it to fill voids . The toe of the armoring will <br /> be a minimum of 3 feet below the existing creek channel thalweg <br /> as described below. ESG will keep enough material stored on the <br /> mine to complete armoring needed on an area as it is mined and <br /> ready for armoring. At a minimum 2500 cubic yards will be <br /> stockpiled on the mine for use in armoring. This is enough to <br /> armor a minimum of 500 feet of excavation bank and 500 feet of <br /> channel bank. The stockpile of armoring material will be placed <br /> parallel to the water flow so it will not interfere with flows in <br /> the flood plain if flooding occurs and within the 150 foot <br />