ST. LOUIS — The region’s sewers, creeks and storm drains were no match for last week’s record-shattering rainfall — a downpour remarkable not just for its unprecedented total, but also for its intensity. Pouring water sprawled over creek banks, across roads, and into homes and vehicles, stranding hundreds and killing two. Levees overtopped in St. Peters and the Metro East. Sewers backed up across the region. But unlike the frequent floods along the area’s major rivers in recent years, water from within was a primary danger this time, as many low-lying neighborhoods filled with rain far faster …