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Determ- Assigned Specialist ination Resource Rationale for Determination. Initials Date (N)J. Seebach JJB-There is no surface water present,and no communication (N)Project Lead with the water table due to impermeable Mancos Shale beneath the gravel. There are no drinking water consumers within several miles or down-gradient from the pit. JAS—A stormwater pollution prevention plan(SWPPP)would be prepared prior to mining in compliance with Section 402 of the Clean Water Act and would describe measures to minimize erosion and prevent soils from leaving each site during mining activities.The measures outlined in the SWPPP would stabilize Water disturbed areas during and after mining. 3/19/2021 NI Resources/Quality JJB (drinking/surface/ JAS 6/13/2024 ground) El Mitigation: • Pit should be designed to have no overland flow enter or leave the project site.This may entail constructing ditches on the uphill side of the pit to move water around the pit and constructing a berm on the downhill side to ensure no water leaves the pit during heavy precipitation events. • Site should be inspected periodically to ensure that berms,ditches,and other BMPs as described in the SWPPP are functioning properly. (N)B.Wade Would not be allowed on site,except for in vehicles.A port-a- (N)Project Lead potty is permitted during crushing operations and must be NI Hazardous removed after crushing completion. JJB 3/19/2021 Materials BCW 5/15/2024 ❑ Mitigation: (N)Project Lead Reviewed the soil survey for the site.Resource is not present. NP (Prime o lands Unique)(❑) JJB RL 3/19/2021 El Mitigation: (N)Project Lead JJB-Topsoil has already been removed and stockpiled from (N)J. Seebach the pit and would be replaced upon reclamation. JAS-A stormwater pollution prevention plan(SWPPP)would be prepared prior to mining in compliance with Section 402 of the Clean Water Act and would describe measures to minimize erosion and prevent soils from leaving each site during mining activities.The measures outlined in the SWPPP would stabilize disturbed areas during and after mining.Design features would JJB 3/19/2021 NI Soils address concerns about the resource within the project area. JAS 6/13/2024 ❑ Mitigation: • The site shall be inspected periodically to ensure no erosional features are forming at the site and if discovered,stabilized at the earliest practical time. • During reclamation of the site,all final slopes shall be 3:1 or less unless it can be demonstrated impractical for discrete areas beforehand with the concurrence of BLM. Disappointment Valley Gravel Pit Expansion EA DOI-BLM-CO-S010-2024-0021-EA Tres Rios Field Office 24