Bukit Mandai II: From Hill to Hole II

Summary: Bukit Mandai II used to be the 9th highest hill on the island of Singapore. Granite quarrying since the 1920s has reduced the height of the hill and created a large hole. The remnants of this hill is now loosely known as Gali Batu. It sits behind the Gali Batu bus depot, not far from Woodlands Road.

Figure 1. Comparison between a 1939 map (Top) [1] and 2005 map (bottom) [2] showing the before and after of the quarrying activities which decimated Bukit Mandai II. In the bottom map, the red triangle marks the spot where the summit used to be.

This hill would have been the 9th tallest hill in Singapore if non of the Singapore's hills have had their head shaved off or quarried to non-existence. Bukit Mandai II originally had a height of about 305 feet (or about 93 m) and is situated about 1.2 km southwest of Bukit Mandai. The remnants of this hill is now loosely known as Gali Batu, which roughly means "Rock/Stone Digging" no doubt originating from its quarrying past. It sits behind the new Gali Batu bus terminal, not far from Woodlands Road.

On maps, it was an unnamed peak till the 1930s. The first mention that I can find of the name Bukit Mandai II came in the 1939 topographical map of Singapore [1]. 

Granite quarrying activities at Bukit Mandai II seems to have begun in 1925 [3]. This was the original 'Mandai Quarry' (Not to be confused with the later quarries associated with Bukit Mandai), and was owned by the Singapore Municipal Council and Singapore Harbour Board. The quarry was connected to the FMSR (Federated Malay States Railway) line and allows the quarried granite to be transported over to the Southern end of Singapore island for the construction needs around Singapore Harbour (Today's Harbourfront area). On the 1939 map in Fig. 1, is "Topham, Jones & Railton", who was the building contractor for the harbour construction (They were also the building contractor for the Causeway and many other civil and military works in Singapore then). 

The 290 feet marked on the 1939 map in Fig. 1 and labelled "Bt. Mandai II" is not the highest point. A higher point is situated at a point about 100 meters south of the 290 point. The contour line is at 300 feet, and so I will estimate this highpoint to be 305 feet. Throughout all the maps that I have come across, this highpoint has remained unlabeled, so technically I am wrong here to name this high point 'Bt. Mandai II', but that is just some academic detail.

Figure 2. Portion of the 1953 Topographical Map Of Singapore [4] showing the encroaching quarrying activities of "Mandai Quarry". The read triangle maps the summit of Bukit Mandai II, perilously close to the edge of the quarrying hole.  

From the 1953 map (Figure 2) [4], you can see the quarrying activity eating away the hill. By about 1970, the 305 feet highpoint is gone, and the 290 feet (88 m) became the highpoint of Bt. Gombak II, which you see in the 1975 map (Figure 3) [5]. Further quarrying ensures that that point itself eventually also disappeared about late 1980s to early 1990s.  

Figure 3. Portion of the 1953 Topographical Map Of Singapore [4] showing the encroaching quarrying activities of "Mandai Quarry". The read triangle maps the summit of Bukit Mandai II, perilously close to the edge of the quarrying hole.  

Nowadays, it is a rather scenic and secluded area (See Fig. 4). It is technically in a restricted area and is off-limit to casual visitors. 

Figure 4. View of the remnant of Bukit Mandai II. View from the west edge of the quarry 'hole'. 

       
Reference
[1] Singapore & Johore, (Survey Department, Federated Malay States (F.M.S.) and Straits Settlements (S.S.), 1939). Retrieved from National Archives of Singapore.
[2] Singapore Series L802 Edition 10 SMU [1:25,000 Topographical Map] (Mapping Unit, Ministry of Defense, Singapore, 2005). Retrieved from "Historical Maps of Singapore, digitised by Department of Geography, National University of Singapore." https://libmaps.nus.edu.sg/  
[3] http://searail.malayanrailways.com/Industrial/industrial.htm
[4] Provisional Issue [1:25,000 Topographical Map of Singapore] (Survey Department Federation of Malaya, KL, 1953). Retrieved from "Historical Maps of Singapore, digitised by Department of Geography, National University of Singapore." https://libmaps.nus.edu.sg
[5] Singapore Series SMU 025 [1:25,000 Topographical Map] (Mapping Unit, Ministry of Defense, Singapore, 1975). Retrieved from "Historical Maps of Singapore, digitised by Department of Geography, National University of Singapore." https://libmaps.nus.edu.sg/