the engineering is not hard, but the venturi siphon and LOTS of hose is crazy expensive for a one time use. The de-watering bags are also expensive, and you'll need heavy equipment to move them, and a downstream place for dumping spoils after drained.

Given the comparatively small size of your pond, Draining the pond then getting a track loader or hoe to clean it out, deepen, and spread muck on the dam's backside should take a day or less. That should cost way less than suction and de-watering, and be far more complete.