According to the subsidence of the dumper room in Xinmi Power Plant and the existing foundation treatment, a pressure grouting reinforcement scheme was formulated with proper construction equipment and parameters determined through the trial-hole. In order to address the gravel backfill foundation, sim-casing drilling with the eccentric bit was used to avoid hole collapse and ensure the smooth progress of construction, and alternate grouting ensured good grouting results. The subsidence observation results show that the design and construction scheme is proper and effective, providing a better idea for the treatment of similar projects.