Vacuum trucks were scheduled Monday to begin sucking out the silt, sand and trash from drains still affected by the September 2008 hurricane.
The Federal Emergency Management Agency is paying to deep clean Galveston's storm drains.
The Galveston County Daily News reports work is expected to be completed by March 12.
The city plans to use the removed sand and silt to elevate Galveston's recycling center, in a plan endorsed by the Texas Commission on Environmental Quality.
City crews have been clearing hurricane-clogged drains in response to complaints about flooding, but the workers have been unable to clean the whole system.