宮城県内におけるオープンループ方式地中熱システム導入に係る地下水利用規制の諸課題

抄録

Legal regulations related to various laws and prefectural ordinances were investigated in view of promoting geo-heat systems using groundwater in Miyagi Prefecture. It was clarified that there were four major issues: (1) the clarification of the applicable scope of “industry” in the Industrial Water Act, (2) the problems with pumping wells outside the definition of the Industrial Water Act, (3) the deregulation of groundwater pumping only for geo-heat systems, and (4) the deregulation of underground seepage in groundwater restoration. As a result of inquiries and discussions about issue (4) with Miyagi Prefecture, Sendai City, and the Ministry of the Environment, Miyagi Prefecture revised their ordinance that if water is returned to the same aquifer from which it was pumped without changing the quality of the water, it does not correspond to underground seepage. Regarding issue (2), the prefecture and city allowed multiple unregulated pumping wells with discharge openings 6 cm² or less of total cross-sectional areas to be installed on the same site to pump water from aquifers shallower than 300 m regulated. These revisions and permissions to the law and ordinance are expected to expand the use of geo-heat systems using groundwater in Miyagi Prefecture.