1986년 4월에 시화지구 개발타당성 조사 및 기본계획이 마련되어 시화지구 건설사무소가 설치되기에 이른다.
In April 1986, a feasibility study was conducted and a basic plan for the development of the Sihwa District was prepared and the construction office of the Sihwa District was established.