The Washington Surburban Sanitation Commission will spend $1 billion to complete a federally mandated repair, replacement and rehabilitation project.

The utility, which serves about 1.8 million customers in Montgomery and Prince George’s counties, has until December 2015 to complete the project.

About 5,000 pipes and manholes in 24 of the system’s 29 sewage basins need repair, said Mark Behe of the WSSC sewer rehab unit.

Many parts of the repairs are in environmentally sensitive areas such as along waterways or in parks, Behe told the Montgomery County Planning Board on Thursday.

Most of the pipe repair requires adding a lining that essentially will become a new pipe inside the old one and will last 50 to 100 years, he said.

Planning Commission Chairwoman Francoise Carrier asked if the repairs will mean rate increases for WSSC customers. Behe noted that rates already have gone up for customers.

kalexander@gazette.net