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arca,a.Inc. A RCOSA Exhibit G — Water Information The following Exhibit G describes the water management activities for Arcosa's LWB mining and processing facilities, Including a description of surface water hydrology, a description of groundwater hydrology, Identification of wells, springs, tributary waters, reservoirs, and ditches on affected lands and adjacent lands, a description of water quality protection, an estimate of project water requirements and sources, and a description of water discharge permits for the facility A comprehensive description of the surface water hydrology and groundwater hydrology for this site was originally presented in the report,Engineering Design and Operations Report, prepared by Sergent, Hauskins & Beckwith in 1992 for the Western Aggregates, Inc (former owner) proposed Shale Mine Ash Backfill Project' The descriptions provided below are based on relevant Information from the Report as well as updated information to reflect current hydrologic conditions As noted in a letter from the State Engineers Office (SEO) to DRMS in 1994 in response to a prior permit amendment application, the SEO concluded that there were no impacts to surface water or groundwater quality from the mining activities.There has been little to no change to the mining activities since 1994 thus, water from the operations is not expected to Impact water quality Surface Water Hydrology Surface water features(e g., drainage basins, creeks, canals)within 2 miles of the affected lands are shown on Exhibit G-1 Features include Coal Creek, the South Boulder Diversion Canal, and Rocky Flats Lake. Surface water west of State Highway 93 around the quarry area flows to and develops Into concentrated flow that channelizes in nearby Coal Creek Surface water east of State Highway 93 generally flows overland to the west according to topography and is channelized in diversion channels or swales adjacent to State Highway 93 which ultimately flow west under State Highway 93 and toward Coal Creek Coal Creek is a natural braided stream channel that is cut in the Pierre Shale formation. Coal Creek flows to the northeast along the west and north sides of the western most portion of the affected lands.A saturated coarse gravel, ranging in thickness from 15 to 20 feet, fills the creek bed. The water level within the gravel layer and in Coal Creek fluctuates seasonally and in response to water drawn off by irrigation. The gravel layer recharges seasonally due to rain events and stormwater runoff from surrounding areas, and likely contributes water to the creek flow and surrounding up-gradient deposits such as the Rocky Flats Alluvium during dry periods The South Boulder Diversion Canal is located to the south and west of the affected lands. The canal diverts water from Eldorado Canyon, located west of the affected lands, to the south where it empties into Ralston Reservoir The nearest portion of the Boulder Diversion Canal lies approximately one-half mile southwest of the quarry area. Based on the topography of the areas surrounding the affected lands, stormwater would likely be intercepted by Coal Creek prior to reaching the canal Given the distance from the quarry, regional ' The proposed Ash Backfill protect was approved by the Colorado Department of Health in 1993,however,the protect was dis- approved by Jefferson County The comprehensive summary of regional and local geology,hydrogeology and other pertinent information, including figures and exhibits,from the Sergent,Hauskins&Beckwith design report are discussed in this permit