|
CNAPTERFIVE
<br />Draft EIS Reuislons
<br />n.,.,,.,a.,..,«o. ,.,,.,r.«,. ,a.,,., ,.,.ne,.«oa ,t.,.:..,. ,~.:n:..,. ,.r n...o.:...,.. c,.a.. ~.,h ..:....... :..... .an ~n_~
<br />.,:«,..:..... ,en ~n c ..a ...,.o. ~,,.,.,t„ .,.en ~n v .,a:..~.o ~rric ,. a..«..,«:....~ :., «ho t t:.,..,
<br />~',,......,«:,... _ ..e.7 f ...., oAA ... 7 01tn ..,../1 .,..io.,,t,~ ~..... 1C7 ... ~Gn f o« 1..,~ :.. rho i T:.,«~
<br />I~1
<br />U
<br />Page 3-20
<br />...
<br />1~>,AC.
<br />Mean values for fluoride (4.12 to 5.02 mg/1), TDS (1,640 to 2,130 mg/1), iron (0.81 to 1.25 mg/1),
<br />and manganese (0.06 to 0.12 mg/l) exceed Colorado groundwater standazds for samples from
<br />both wells. Sulfate exceeds the standard in 8 of 17 samples from we1120-5. Chloride and zinc
<br />also exceed the standard in one sample each. All values for nitrite were non-detect; however, the
<br />detection limits varied from 0.01 to 25 mg/I. Therefore, based on the EPA method of calculating
<br />means, the mean value for nitrite (1.51 mg/1) exceeds the standard. For we1120-8, sulfate
<br />exceeds the standard in 4 of 19 samples, chloride and chromium exceed the standazds in 1 of 20
<br />samples each, and cadmium exceeds the standard in 1 of 4 samples. The detection limit for the
<br />we1120-8 is above the standard.
<br />Groundwater quality monitoring performed by WRN at its nahcolite solution mining operation
<br />about 2 miles west of the proposed project is summarized in Table 3.4-4 (WRN 1997). Three
<br />WRN wells were completed in the
<br />at about 300 feet bgs. Water
<br />samples collected from these wells is similaz to that recorded for the alluvium and the Uinta
<br />Formation at the Project Site. TDS concentrations range from 504 to 1,644 mg/1, with a mean of
<br />868 mg/1 for the three Upper Aquifer wells at the WRN site. Mean values for fluoride (7.51
<br />mg/1), TDS (868 mg/I), iron (4.69 mg/1), and manganese (0.1 mg/l) exceed the Colorado
<br />groundwater standazds for the upgradient Upper Aquifer well. For the two Upper Aquifer wells
<br />completed at the remote downgradient monitoring site, mean TDS values (768 and 608 mg/1)
<br />exceed the standard. The mean concentration of 'iron exceeds the standard in one well.
<br />Maximum concentrations of sulfate, chloride, aluminum, lead, and manganese also exceed the
<br />standazds for one or both wells.
<br />Additional water quality information for the Upper Aquifer is provided by historical analyses of
<br />samples from wells identified by the USGS database seazch. Table 3.4-3 provides a summary of
<br />the analytical results for five samples collected from one Upper Aquifer wells. TDS ranged from
<br />700 to 9,600 mg/1 in this well, with a mean of 2,620 mg/l. Mean concentrations of TDS (2,620
<br />mg/1), chloride (730 mg/1), fluoride (15.8 mg/1), and iron (0.35 mg/1) exceed Colorado
<br />. groundwater standazds. Sulfate exceeds the standard in 1 of 5 samples, and iron exceeds the
<br />standard in 2 of 5 samples from this well.
<br />5-13
<br />
|