What was placed over the sump in the trenches of world war 1?

During World War I, trenches often had a sump to collect water and waste. To manage this, a cover or lid made of wood or metal was typically placed over the sump to prevent debris from falling in and to reduce the risk of disease. This practice helped maintain hygiene in the unsanitary conditions of the trenches, which were often flooded and filled with stagnant water.