(Portland, OR) -- Portland's Big Pipe did its job during the heavy rain. The Portland Bureau of Environmental Services says the pipe filled with combined storm runoff and sewer water to 100-percent capacity, but there was not an overflow into the Willamette River. After about an hour at capacity, the level in the Big Pipe started to decline. The Big Pipe is a large underground storage tank the gives the sewage treatment plants time to process waste during periods of heavy rain.