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<br />VII-9 <br /> <br />. <br /> <br />the water yielding properties. The composition vari~s in the Carbondale <br /> <br /> <br />Valley from fine silt and clay to coars,' sands and gravels. No trends have <br /> <br /> <br />been noted regarding areas composed of coarse-grained material or those com- <br /> <br /> <br />posed of fine-grained material. It appears that the grain size distribution <br /> <br /> <br />varies from locality to locality and is found in lens-like deposits laid <br /> <br /> <br />down in a shifting river channel. <br /> <br />, <br />The alluvial material in the Carbondale area can be separated into two <br />J <br />aquifers, the Crystal River Alluvium and the Roaring Fork River Alluvium. <br /> <br />Appendix D includes test results and locations of well water samples taken <br />in the Carbondale area. <br /> <br />. <br /> <br />From data collected to date, the Crystal River Alluvium is relatively thin, <br /> <br /> <br />extending 20 to 70 feet below ground surface. Water quality in this alluvium <br /> <br /> <br />is highly variable, depending upon the source of recharge. Hardness is gen- <br /> <br /> <br />erally near the critical concentration. In most wells sampled in the Cry,tal <br /> <br /> <br />River Alluvium, the hardness values exceed 300 ppm. The quantitative charac- <br /> <br /> <br />teri,.tics of the Crystal River Alluvium are highly variable with reported <br /> <br /> <br />yields ranging from less than 5 gpm to more than 100 gpm. <br /> <br />The other source of alluvial ground water is the alluvium north of Carbondale <br /> <br /> <br />and adjacent to the Roaring Fork River. Four wells were inventoried in the <br /> <br /> <br />vicinity of the Roaring Fork. Three of these wells were somewhat distant to <br /> <br /> <br />the stream and indicate hardness values of near 300 ppm. However, the four <br /> <br /> <br />wells pump small quantities of water (i .e. about 5 gpm) and therefore, it is <br /> <br /> <br />assumed, receive very little di rect recharge from the Roaring Fork. Other <br /> <br /> <br />than these small capacity domestic wel Is, additional wells have not been <br /> <br /> <br />reported in the Roaring Fork Alluvium in the immediate Carbondale area. <br />. <br /> <br />In the Basalt area a number of wells have been drilled into the Roaring <br /> <br /> <br />Fork alluvium and have reported good yields. Near the Basalt sewage treat- <br /> <br /> <br />ment facilities, three wel Is were drilled to shallow depths of about 30 feet. <br /> <br />. <br />