Assuming base is a square, then the total surface area of the pyramid is the area of the base plus the areas of four equal isosceles triangles with a base length of the side of the square and height equal to the slant height s of the pyramid. So 230.4²+(4/2)230.4s=136212.5, 460.8s=136212.5-53084.16=83118.34. Therefore s=180.38m approx.
The slant height of the pyramid, its height h and half the length of the base side (115.2m) form a right triangle, where s is the hypotenuse. Therefore h²=s²-115.2²=19625.31, h=138.8m approx.