careful inspection of the pipe showed "lenses" of concrete. Some of these lenses were held slightly outward due to hold the crack open. Generally, the cracks had not been open long enough for soil enter the pipe
the concrete of the header wall surface at the pipe's discharge had deteriorated sufficiently to expose cf of the coarse aggregate up to about half of the pipe's diameter.Other intervals of deterioration could be seen above this line, with the concrete surfaces progressively more deteriorated from top to bottom. The interior of the pipe that could be observed was similarly deteriorated