Plum Island’s 145 fire hydrants will be replaced now that Newburyport has awarded a $3.25 million contract to Salem-based contractor Granese & Sons. The hydrants contain inferior materials and low-quality workmanship; they were installed a decade ago as part of a larger water and sewer project. Newburyport received about $4.5 million last year after CDM Smith, Inc., the Boston-based engineering firm that oversaw the original Plum Island project, agreed to a financial settlement. The replacement project will mean water shutdowns, road detours, and possible road closures because of repaving. A detailed schedule for the multiyear project is available by contacting the city’s Department of Public Services at 978-465-4464, ext. 1701, or firstname.lastname@example.org.Linda Greenstein can be reached at email@example.com.