jdonville,
Thanks for your response.The "unbalanced hydrostatic forces" that we are discussing arise from the following assumptions:1.The manhole itself is empty. 2.The compacted backfill around the manhole (plus the weight of the concrete) resists the bouyancy due to saturated soil conditions...
In our office there is a discussion of the need for reinforcement in the concrete slab for 4 foot diameter wastewater fiberglass manholes. The manufacturer recommends a minimum six inch concrete pad poured to anchor the manhole with additional concrete poured inside the manhole to form a channel...
