Development of a groundwater monitoring system at Horonobe Underground Research Center

Nanjo, Isao; Amano, Yuki   ; Iwatsuki, Teruki  ; Kunimaru, Takanori; Murakami, Hiroaki  ; Hosoya, Shinichi*; Morikawa, Keita

The observation technique of hydrochemical condition in low permeable sedimentary rock around the facility is one of R&D subjects. We report, (1) development of hydrochemical monitoring system to observe water pressure, pH, electric conductivity, dissolved oxygen, redox potential and temperature, (2) hydrochemical observation results around URL under construction. The applicability of the hydrochemical monitoring system is evaluated for low permeable sedimentary rock bearing abundant dissolved gases. The hydrochemical observation during facility construction demonstrates that pH and redox potential of groundwater almost did not changed even at hydraulic disturbed zone (water pressure decreased zone).