Suggestions sought for DIY cleaning of accumulations of solidified, clay
based sediments from long neglected roadside culverts ?

Some culverts run under the pavement of single-lane neighborhood private
lanes and are pretty accessible from at least one end. Others running
parallel to the pavement (e.g., at driveway accesses) tend to be filled in
at the ends and less accessible. Most culverts are cement construction
(some corrugated steel) and range from 8 to 20 inches inside diameter and up
to 20 feet in length. Some are almost 90 percent blocked.

Ideas so far include high pressure hose (but limited water supply from
wells, no city water) and some sort of scrapers affixed to ends of lengths
of metal pipe (not convenient where culvert ends are not accessible above
grade).

David Merrill