Control of naturally occurring brine springs and seeps in an evaporite karst setting

摘要

Naturally occurring brine springs and seepscontribute a daily average of 3300 metric tons of chloride to theRed River through its tributaries. A study to control brinedischarges, thereby improving the water quality of the Red River,has been performed.The study area is located just east of the high plains in theRolling Plains subdivision of the central lowlands physiographicprovince of Texas. Dolomite units throughout the area arefractured along bedding planes, vuggy in places and wathered.Gypsum units are massively bedded to interbedded with thinlayers of dolomite. Cavities occur in either dolomite and / orgypsum. Dissolution of these units has formed sinkholes and depressions.The major source of brine discharge in the study area isthrough springs and seeps. Springs and seeps occur because thepotentiometric head of the brine is higher than the creek bedelevation, and permeability of materials in the discharge area islow compared to the surrounding area.A drilling program and pumping test was performed todetermine the number and location of wells, and pumping rates tocontrol the brine discharge from the area.Transmissivity of the bedrock aquifer system ranges from 149m2 day –1 (12000 gpd ft –1), with an average of 2108 m-2d-1(170000 gpd ft –1). The high value of transmissivity is indicativeof the karst nature of the bedrock aquifer system.During the study, the chloride load in the creek was controlledas a result of elimination of brine spring discharge. Naturallyoccurring brine springs and seeps in the study area, an evaporitekarst setting, can be controlled by installation and operation offour shallow collection wells at a combined pumping rate of 5.86m3 m (1500 gpm).