The concerns of the condition of the spit my not be bad. In fact, if they are buried 40 in the ground and in creates, they are all protect from the environment of Burma. However, the location could change my remarks as well as yours. Most of Burma lies between the Tropic of Cancer and the Equator. The Tropic of Cancer divides the country into two regions: the tropical south that covers two-thirds of the country, and the sub-tropical and temperate north, which is the remaining one-third of Burma. This causes two distinct seasons: the dry season from mid-October to Mid-May, and the wet season.
There is a cooler spell during the wet season from December to February. The coastal regions and the western and southeastern ranges receive more than 200 inche of precipitation annually, while the delta regions receive about 100 inches. The central region is not only positioned away from the sea but also on the drier, lee side- in the rain shadow- of the Rakhine Mountains. Precipitation gradually decreases northward until in the region’s dry zone it amounts to only 20 to 40 inches per year. The Shan Plateau, because of its elevation, usually receives between 75 and 80 inches annually.
With that you need to look at the type of soil that they buried it. Burma dominate soil group is acrisol. From what I read, acrisol has a pourops surface soils under the protective of the forest. This hold true for most soil groups in Burmuda. However, when not protected, the A-horizon is degraded and slakes to form a hard surface. This will aloud insufficint penatration of the water during the wet season. The info that I am trying to find is how deep the horizon are and better info on the properties. From the sound of it is really deep if they are to buried it 40 feet.