The implications of DSTP on the Markham Canyon.

A GEOLOGY AND NATURAL HAZARDS study of Lae city by Buleka et al (1999) remains one of the best-studied documentation of the area between the Markham river and Busu River. This is also the area of interest to the DSTP. The Wafi Golpu (WG/JV) Environmental Impact Statement (EIS) only make 2-3 references to this document, but do not go into the parts of the report that describes the geo hazard of the areas. In this report, the area of study is described as;

“a very complex geologic environment dominated by the effects of turbidity currents, submarine landslides, debris flows and erosion.”

“The sea floor features suggest that there may be considerable interaction and interdependence between the processes, and factors making it difficult to separate precise cause – effect relationships. The observed sea floor features likely represent the combined effects of both short and long term factors, such as annual river discharge and rapid sediment supply, annual sea floor erosion, episodic earthquakes and uplift/subsidence events, changes in the locations of river mouths, and long term regional uplift and subsidence.”

The status quo as reported by Buleka et. al. (1999) is based on the sedimentation rates from the existing river (Markham, Busu and Bumbu rivers) under the existing rain regime and geological plate movements. However, with the extra tailing placement which will be flowing on a daily basis – this is equivalent to increasing the sediment load from the Busu. In other words, it is like making a new river.

….. Markham River discharges 2 million tons of sediment load per year, while Busu discharges slightly less than Markham (Buleka et al (1999).

The mine is predicted to discharge 360,000 million tons over 28 years. that is about 12,857 million tons per year on top of the load from Markham and Busu. In other words, the DSTP is like a big river that is discharging a sediment load that is over 6,000 times bigger than Markham. This will be deposited into the Markham Canyon. Could the Markham canyon stand the increased sediment load?

According to the Buleka report, the continental shelf on the Busu side runs for 500 m before it reaches the Markham Canyon. According to the mine plan, if tailings pipe end at 200 m, there is another 300 m before the canyon. If there is a sediment build up and then eventually a slump – there is enough load to cause a tsunami. Or it may clog Markham canyon changing the bathymetry of the existing system affecting the current Lae Wharf location.?

The Huon Gulf sees two prevailing currents during the year. The South East trade winds that blow from the south piling water against Lae city and squeezing part of it out through the Vitiaz Strait. ?The North westerly that blows water from the Bismark through the Vitiaz Strait and into the Solomon sea.

Buleka et al (1999) demonstrate long shore drift from Busu and offshore environment hitting the Lae area between Voco point and the main wharf. Longshore waves is always in the direction of prevailing wind.. Longshore drift can cause?erosional or depositional effects as observed with sediments filling up of Vocco Point to the eroded coastline further toward DCA Nambis. Increased sedimentation from the mine waste has implications for Lae city waterfront and the Lae Port which have bigger economic implication on Papua New Guinea.

Furthermore, other studies have measured up to 170 earthquakes in this general area between 2000 and 2016. Indeed, it is unpredictable the stability of increased sediment placement into the Huon Gulf.

The implication on Lae city as a home, as well as the landing site for cargoes for economic development is unknown . We say NO to DSTP into Huon Gulf because long term impact is unknown and unpredictable. Without knowledge, we are compromising our future for short term economic gain.

Reference

BULEKA, J., PRIOR, D., VAN DER SPEK, A., (1999) GEOLOGY AND NATURAL HAZARDS OF LAE CITY AND SURROUNDINGS, PAPUA NEW GUINEA. CCOP COASTPLAN Case Study Report No. 3 Geological Survey Division, Department of Mineral Resources, Papua New Guinea