The Dalles Public Works will begin on Monday to replace a section of deteriorated pre-1909 steel water main line on Trevitt Street.  Traffic control, detours and road closures will be in effect for the duration of the water line project that is expected to take eight to ten days to complete.   This work is being done in preparation for the repaving of Trevitt Street.  On Monday Trevitt Street will be closed beginning at 7 a.m. to thru traffic from West 6th Street to West 7th Street.   Flaggers will be at the intersection of West 6th Street and Trevitt Street to direct one lane traffic through the work zone.  West 6th Street will be opened up to two lane traffic at 5:00 pm.  On Tuesday, Trevitt Street will remain closed to thru traffic.  Motorists are encouraged to use Bridge and Garrison Streets as alternative routes to avoid the work area.  Meanwhile, crack seal work will take place during the first portion of the week on various streets in The Dalles.