Hydrogeochemistry in the coastal area during construction of geological repository

Youn Tae Kim, Seung Gyu Hyun, Jae Yeol Cheong, Nam Chil Woo, Sangdeok Lee

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A geological repository for low and intermediate radioactive waste (bottom at −130 m a.s.l.) was constructed from 2008 to 2014 in the southeastern coastal area in Korea. This research aimed to evaluate the hydrogeochemistry in this area during the construction period and to determine the characteristics that should be monitored during the operational period. During construction, the groundwater level decreased up to 136 m and the upper groundwater flow in the southeastern area reversed. After the groundwater level dropped below the sea level, the electrical conductivity (EC) in several wells along the coastal line started to increase; 23.2% of the measured water was classified as brackish water and the highest EC observed in groundwater was 18.9 mS/cm, nearly 38% of EC in seawater. The response time of the groundwater chemistry differs depending on the depth, even in wells, because of fracture networks. Among locations that showed drastic changes in EC, only the shallow depth of GM-4 showed a peak pattern in EC, but other locations showed increasing EC patterns or patterns with initial increase and sustained high till the end of the construction period. Based on the Cl/Br ratio, the source of the groundwater salinity was seawater intrusion, and ion exchange played an important role. Compared to Cl concentration, sodium was depleted and calcium was in excess in brackish water; however, the SO4/Cl ratio remained constant at a level similar to seawater. Ca and Fe concentrations showed distinguishable characteristics depending on the location, suggesting differences in geological media. During the operational period, periodical evaluation of the groundwater chemistry in the mixing zone and continuous monitoring of EC patterns and seawater fractions are required.

Original languageEnglish
Pages (from-to)40-49
Number of pages10
JournalJournal of Hydrology
Volume562
DOIs
Publication statusPublished - 2018 Jul 1

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hydrogeochemistry
repository
electrical conductivity
groundwater
seawater
brackish water
well
fracture network
coastal area
radioactive waste
groundwater flow
ion exchange
calcium
sodium
sea level
salinity
monitoring

All Science Journal Classification (ASJC) codes

  • Water Science and Technology

Cite this

Kim, Youn Tae ; Hyun, Seung Gyu ; Cheong, Jae Yeol ; Woo, Nam Chil ; Lee, Sangdeok. / Hydrogeochemistry in the coastal area during construction of geological repository. In: Journal of Hydrology. 2018 ; Vol. 562. pp. 40-49.
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Hydrogeochemistry in the coastal area during construction of geological repository. / Kim, Youn Tae; Hyun, Seung Gyu; Cheong, Jae Yeol; Woo, Nam Chil; Lee, Sangdeok.

In: Journal of Hydrology, Vol. 562, 01.07.2018, p. 40-49.

Research output: Contribution to journalArticle

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