This paper studies the feasibility of the Time Lapse GRP (TLGPR) to be a monitoring measures for deep excavation works. The TLGPR aims to quantify the difference between two radargram collected along boundary of construction site at different time. It provides an information on the degree of change, or even formation of void, in the soil mass being retained by lateral support. Non-signal processed data (256 samples per trace) were input to an in-house LabView programme for Wavelet Transform (WT) to determine the peak frequency of A-scan at particular time-depth. By comparing the differences in peak frequency at different time, changes in soil mass identified. Result shows that the TLGPR able to quantify the degree of change between two radargram. Moreover, due to the TLGPR is comparing the difference in frequency domain, it is capable to identify differences which are not visually notable from signal processed image.