Drainage design covers storm drain systems, culverts, ditches, and stormwater management. Design storm frequency: Interstate 50-year, arterial 25-year, collector 10-year. Culvert design per FHWA HDS-5 using HY-8 software. Storm drain systems designed using the rational method for areas <200 acres and NRCS methods for larger watersheds. Stormwater quality per MA MS4 permit requirements and Massachusetts environmental regulations.
All work under this section shall comply with MassDOT current standards and applicable AASHTO, ASTM, and federal requirements. The Engineer has authority to accept or reject materials and workmanship that do not conform to the specifications.
Source: MassDOT Highway Design Manual, 2024 Edition. Pages 23–24 of 37.