Hi George, yip, that former patio area will be a pond shortly . That sump-hole is for the pump,....lowest point in the pond. Will also serve as a bolt hole for the fish if Mr Heron or MrCat show up lookin for a fish meal. I'll be workin on this area for the next few days. Lot of work still to go before its complete . Will get lined with thick wet newspaper,then the butyl pond liner's next. Then more cement and stone work to dress it, water plants etc., ...anyway watch this space George !!