Item 1: PH on Ordinance Amending Metro Plan (Delta Sand and Gravel)

Home Browse Search

ongoing compliance with the ACDP requirements ensures that any potential dust conflicts from any of those activities is and will be minimized. We find that the applicant’s requirement to operate all expansion area mining and processing activities in conformance with the current LRAPA ACDP (modified to add the expansion area to the existing permit and its requirements), and the applicant’s demonstration that it will operate within the expansion area in conformance with the permit requirements provides a legal basis to conclude and find that any potential dust conflicts from the proposed mining of the expansion area have been, and will be, minimized as required by Goal 5. Flooding EGR has concluded that the Delta Sand and Gravel Company method of mining will create no obstructions or other physical features that could impede flood flows across the proposed expansion area. Essentially that conclusion means that flood flows should not be impeded across the proposed expansion area if no fill within the floodway occurs. All mining activity proposed for the expansion area will occur as excavation taking place below existing ground surfaces. Within that mining methodology overburden will be removed and stockpiled in areas higher in elevation than base flood elevations and/or stockpiled at locations on company property that are below existing ground elevations. EGR concludes that the proposed mining methodology on the proposed expansion area will not impede flood flow, reduce flood storage volume within the flood plain or increase the velocity of water flowing across the proposed expansion area. EGR further concludes that the proposed mining methodology completely avoids all potential flood impacts. Opponents of the application argue that the existence and operation of the aquaclude (see subsequent discussion and findings regarding the aquaclude) will cause flooding on adjacent residential lands because groundwater will be prevented by the aquaclude from migrating from those lands to the mining site during heavy rain events. EGR has addressed that argument and has demonstrated, in its rebuttal materials provided during the planning commission joint public hearing and deliberation, that the movement of groundwater is not connected to surface water that constitutes flooding during such events. Nonetheless, in response to the opponents’ argument, the applicant and EGR have provided a modified aquaclude construction that leaves the top elevation of the clay-filled aquaclude one foot below the measured elevation of the wetland that exists on the meandering scar, approximately six to eight feet below ground surface. While continuing to impede the rate of flow of groundwater from the adjacent property to the expansion area (and mining pit), the aquaclude would allow the passage of a limited amount of groundwater from the adjacent property, over the clay material and into the mining area during heavy rain events. That elevation will also ensure that the aquaclude has no negative impact on the water level of the wetland at different times during the year. We find that EGR has provided significant evidence to support it conclusion that the aquaclude will minimize potential conflicts resulting from the movement of groundwater from adjacent lands to the mining area and that its existence and operation will not produce flooding on adjacent lands. We find that approval of the application will not result in flooding conflicts with adjacent land uses. Groundwater EGR recommends that a low permeability barrier, groundwater dam or other flow restriction of the upper aquifer should be constructed, at the applicant’s expense, as the excavation proceeds to the west. EGR concludes that the construction of a low permeability barrier could actually result in lower pumping of water, with significant benefit to the aquifer and Page 17 – FINDINGS OF FACT