Do an animation

I have a client who wants an animation made for their website landing page. It's for an engineering firm. The idea is to have a 5-10sec long animation that willl run in a loop on the home screen landing page of their website. The animation is basically 3 separate images, each of an engineering project (house, factory, civil) for example and the animation needs to start off like someone drawing a chalk sketch of the picture. After the sketch is drawn, the actual image should fade in from the back replacing the drawing and revealing the real picture. 3 images, three separate animations. I'll add the pictures once received. Bidding can start in the meantime.