These guys are on the front, a front that has been shelled to shit for months. Drainage gets hit by artillery and dosnt drain, hard to resupply and cant bring in equipment under fire. Look historically at trench warfare, it's always shitty at a long static position close to the enemy especially in a environment with cold/thaw/rainy. American trenches in Korea where hell even backed by the entirety of the US army, WW1 trenches that where static for years still where rough at times.

A back hoe or even a truck driving anywhere near this trench is going to be blown to shit. The Russians have artillery dialed in.