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GENERAL31182
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Last modified
8/24/2016 7:48:32 PM
Creation date
11/23/2007 6:56:52 AM
Metadata
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Template:
DRMS Permit Index
Permit No
M1999002
IBM Index Class Name
General Documents
Doc Date
1/19/1999
Doc Name
DRAFT ENVIRONMENTAL IMPACT STATEMENT CHAPTER 4
From
STEIGERS CORP
To
DMG
Media Type
D
Archive
No
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<br />CHAPTERFOUR Environmental Conseuuences <br /> <br />Proposed Action , <br />Piceance Site <br />Under the proposed 30 yeazs of mining, a significant impact to groundwater would bean ' <br />accidental release of production fluids or migration of these fluids into the Uinta :Formation <br />portion of the Upper Aquifer. Production fluids could potentially be introduced to this aquifer <br />from casing leaks, from the migration of poor quality groundwater from the Low~;r Aquifer, or ' <br />from leakage from the onsite evaporation pond. As presented in Section 3.4, the total dissolved <br />solids (TDS) of the Uinta portion of the Upper Aquifer is typically less than 1,000 mg/1. Data <br />collected by American Soda in the vicinity of the experimental mine site indicated that TDS in ' <br />the Uinta portion of the Upper Aquifer ranged from 944 to 2,980 mg/1. TDS in the Pazachute <br />Creek portion of the Upper Aquifer exceeded 10,000 mg/1. The groundwater in ttie Uinta <br />Formation is classified by the Environmental Protection Agency (EPA) as an underground source , <br />of drinking water (USDV~. <br />The Upper Aquifer could be impacted if a release of production fluids from the well casings ' <br />occurred directly into the Upper Aquifer. Potentially, this release would be the rF~sult of a well <br />casing failure. A release of this nature would result in the degradation of the aquifer by the <br />addition of higher-TDS production fluids being introduced into the lower-TDS water of the <br />aquifer. Quantification of the impacts from a casing failure is not possible because flow rates <br />and fluid concentrations associated with this type of event cannot be readily predicted. However, <br />American Soda's drilling, casing, and well testing/monitoring program should minimise the , <br />occurrence of well failures; therefore, the probability of a lazge volume release o1'high TDS <br />production fluid into the aquifer is believed to be low. , <br />Poor quality groundwater could potentially migrate from the Lower Aquifer if conditions either <br />exist or aze created through the injection of fluids that introduce an upwazd hydraulic gradient. <br />Upwazd gradients exist when the differential pressure (head) between two aquifers is such that ' <br />fluids have the potential to migrate from the Lower Aquifer (higher head) to the 1Jpper Aquifer <br />(lower head). This differential pressure could be induced either by mining soluti~~n leaking from <br /> <br />the cavity along a fault or fracture zone or by the gradual loss of fluid from the casing of the ' <br />wells. <br />In the case of mining cavity leaking along faults or fractures, this may cause enough disturbance ' <br />in the aquifer to diffuse a plume of high-TDS fluid and result in a pressure differ~:ntial between <br />the aquifers. Should a casing leak within the production wells remain undetected for a protracted <br />period of time, the resulting volume of fluid could also result in a change in the differential ' <br />pressure of the aquifers and the subsequent migration of poorer quality water from the Lower <br />Aquifer into the Upper Aquifer. Quantification of the impacts associated with either leakage of <br /> <br />fluid from the mining cavity or from the loss of solution from a casing leak into the Lower ' <br />Aquifer is not possible because the flow rates and fluid concentrations cannot be predicted with <br />any certainty. However, potential low volume releases of high TDS production fluids from the <br />solution mine cavities (e.g., along fractures) would not likely cause significant impacts to ' <br />groundwater quality in either the Upper or Lower aquifers if detected and mitigared quickly <br />through American Soda's well pressure monitoring program. American Soda al~;o believes that <br /> <br />potential leakage of high temperature, saturated brine from a solution cavity would cool rapidly ' <br />4-14 Groundwater , <br />
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