Materials:   Picture frame, foam board, CeluClay brand Papier Mache, basswood strips, finely ground dirt, various model railroad grasses.

Construction:   I started with an inexpensive 11x14 picture frame and a piece of foam board.  Since construction was going to be wet I protected the foam board with a heavy coating of polyurethane varnish - this is a very important step.   I then cut thin basswood into strips and then into planks.  I was not exact in measuring  trying to create a random sizing that I would expect to be the case for the real hardstand.  After cutting the planks I gave them all a wash with acrylic paints. 
Next came the fun part - well, fun if you like gooey messes.  I mixed the CeluClay with water until it was smooth and about the consistency mashed potatoes and spread it over the foam board which was mounted in the picture frame.  Once the area was filled I evened it out with wet hands.  Now comes the tedious part - laying in all the planks.

Once the planks were set I misted some water over them and sprinkled finely ground dirt over the whole scene.  I used a wet paint brush to work the dirt between the planks and to remove the excess from the tops of the planks.  While everything was still good and wet I sprinkled various colors of fine 'grass' followed by randomly placed clumps of larger grass, including some growing between the planks.  A couple of oil stains and it was finished.

This will take a very long time to dry, and you will probably have some shrinking.  I went back a week later when it was close to fully dry and filled in some of the cracks that developed with ground dirt.