Analysis of brick-sewer performance and an understanding of failure mechanisms have saved Seattle more than $40 million in major rehabilitation costs. More than 20 miles of brick sewers, ranging in diameter from 36 in. to 144 in., were constructed in Seattle between 1890 and 1930. These sewers served almost without notice until 1957, when the 145-ft-deep, 72-in. Ravenna brick sewer collapsed. The collapse created a hole in residential Seattle nearly 100 ft in diameter at ground surface (Fig. 1), filling downstream sewers with hundreds of tons of material.