Contractors are set to begin a two-phase street repaving project on Monday. In the first phase, expected to take three to four weeks, contractors will reconstruct Broad Street from Washington Street to Atlantic Street. The second phase involves reconstructing Lewis Street from Atlantic Street to New Ocean Street on the Swampscott line; all of New Ocean Street; and Eastern Avenue from New Ocean Street to close to Lynn Shore Drive. That work is scheduled to begin the first or second week of July and be completed by the second week of August, according to Manny Alcantara, acting commissioner of the Department of Public Works. The construction is likely to cause traffic delays. National Grid, which installed underground electrical cables along the streets that are part of the project, is funding $190,000 of the overall $370,000 cost of the repaving. The remainder is being covered by money from the state’s Chapter 90 local road improvement program.