2019-09-09_PERMIT FILE - M2018063

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Environment, Inc. Page 2 Ellicott Sand&Gravel LLC -M-2017-063 Adequacy response 01 There is no way to totally avoid a stream capture during a 100 year event. We have reached a conclusion that we need to increase the width of the setback in each stage and armor the inner and outer banks using the Urban drainage guidelines. This is intended to prevent a change to the ordinary flow channel and keep normal flows out of the excavated areas and yet still allow for flood relief. To be able to do this we needed to know if the U.S. Army Corps of Engineers had jurisdiction for Black Squirrel Creek. I met with Tony Martinez with the U.S. Army Corps of Engineers on June 20, 2019 to determine want jurisdiction they had along this stretch of the creek within the boundary I put on the maps. Basically he said the Ordinary High Water (OHW) line was the area that is scoured and has little or no vegetation from the past normal water flow events. I revised Map Exhibit C to show the OHW line defined by Mr. Martinez. This means that for most of the permit area construction along the banks is outside Corps jurisdiction and can be built with out a 404 permit. As for drainage, we met with the Upper Black Squirrel Creek Groundwater Commission board and presented the plan and explained the concern about capturing the excess flow. The consensus of the Board was that it would increase the ground water capture, allowing for more recharge and due to the nature of the sand would soak in fast enough to present little problems. The UBSC Groundwater Commission's board felt that if the channel can be preserved, the capturing of the water and soaking in of said water (recharge) would be a benefit to the basin. One idea was that this would be a fairly short time and that Mr. Schubert (the landowner) had enough water to provide evaporative losses for that period. This may be done by not pumping from his well until the captured water has soaked into the ground and show that the volume of the water lost to evaporation would be accounted for as if it were actually pumped from the ground. They also thought because of the unknowns that it would be impractical to try to plan for such an event until it happens. The Upper Black Squirrel drainage board asked Ellicott Sand & Gravel LLC to stay at least 10 feet above the ground water table. We revised the text on pages 19, & 24 and the maps to show this separation as they suggested. I have revised the Mining Plan and Reclamation Plan Maps to show the revised setback an, the approximate location of the armoring areas and the OHW as mapped by the Corps of Engineers. A detailed Bank Protection Plan is supplied with this response and explains how the armoring will be done and has a typical cross section showing how the armoring will be placed. The height will vary but along each side, the bottom of the armoring will be 5 feet below the creek bed on the outside and 3 feet below the creek bed on the inside. The material to be used will be broken concrete and asphalt rubble that meets the definition of Inert Material. Sufficient material will be stockpiled on the site to do up to 500 feet at a time. This amounts to approximately 2500 cubic yards of inert material rubble. This material will be stored in the setback area so it runs parallel to the drainage as shown on