Laserfiche WebLink
~~ ~~~ y <br />~~~' ~ <br />• (~ n, ~ ~/~~ L uCA~II.RB -Exhibit G <br />l\(J' ~' Warer L~farmetion <br />Page S <br />Water level information has been obhained during each monitoring period. A contour map of the <br />potentiomaric surface has been rnnsttucted from the currertt and past water level data. <br />The Pierre Shale unconformtably underlies the valley fill at Dowe Flats. Because it is predominantty <br />comprised of shale, this formation is not oonddaed watet~earictg. Wells south of the project produce <br />small quantities of water from weathered canes in the formation. Below the zone of surficial <br />weathering the Pierce Shale is one of the major low permeability forrctations along the Front Range <br />because of its high clay content. <br />The Niobrara Formation lies below the Pike Shale and is exposed in the southern part of the project <br />area and in the extreme rxrrtherrt part of the project area. There are also scattered outcrops of <br />Niobrara along the higher ridges. 'This formtation also has low permeability and is expected to produce <br />water only from the weathered layer or from zones of secondary perrrteability such as solution cavities <br />or fractures. Solution cavities are not ]mown to exist at Dowe Flats. Ftacxtrce svstans may be vresatt <br />especially on the eastern side o~v ey.'Ife limestone pits south of Colorado Hiphway 66aro <br />• excavated m the Niobrara Formation. These 'ts yield little water from the limestone strata. Because <br />of the thickness and the low pem~teability of the Niobrara ormation, it is antici»atei that rtocte of the <br />deeper aquifers ow the Niobrara will be impacted by the proposed quarry operation at Dowe Flats. <br />Recharge in the unconsolidated valley fill aquifer at Dowe Flats is prirtcrpally from srtowmelt and <br />rainfall. Odrer less significant sources are streamflow and overiying aquifers. The USGS indicxies in <br />Water-Resounxs Investigation 83-4058 that water seeps from numerous reservoirs and irrigation canals <br />into weathered bedrock. The St Vrain Supply Canal, located on the rart}terrt margin of the sine, is <br />a potential source of limited amounts of seepage. This canal flows in the spring and summer and is <br />dry during the winter months. <br />The USGS topographic map of Dowe Flats identifies two springs in the Dowe Flats project area. The <br />locations of these springs are shown on Figure G-3. I.ow altitude aerial photos (approximate scale: <br />1"=400') was examined for evidence of additional springs. No evidence was found. Because the <br />streams are intermittent, there are arras where the emergence of the water in the stmam bed exhibits <br />a seep-like appearance. This can be observed during the spring and summer in the stmam channel <br />• downslrearn from monitoring well DFIvIW-1. Standing water is presort in the stream bed for a <br />