DESCRIPTION: The Minor Street Drainage Improvement project involves replacing two deficient, undersized crossline pipes under Minor Street that outfall into a tributary to Big Creek, while avoiding/minimizing impacts to utilities and eliminating all impacts to wetlands. A previous culvert design impacted wetlands requiring mitigation while avoiding/minimizing impacts to the utilities. The team proposed a bridge to replace the pipes which eliminated all wetlands impacts. A 30-ft (L) x 36-ft (W) hollow-cored slab bridge along with associated roadway and drainage plans have been developed utilizing MASH guardrail standards.

The project was expedited as the road has been closed due to pipe failure causing the roadway to collapse. Although this section is a local road, the project also required coordination with SCDOT as they were developing a sidewalk project for this section as well as the section on their system.  The team provided final roadway and bridge construction plans, bid document, utility report, geotechnical investigations, and SC DHEC permit within approximately 4 months of Notice to Proceed.

CHALLENGES: The team also conducted significant utility coordination with the Town of Williamston, Duke Energy, and other utilities. The project was designed to accommodate a 12” DIP water line, 6” gas line, 6” asbestos water, 1.5” water line, and 8” HDPE sewer line under the roadway pavement structure/roadway shoulder and overhead utilities adjacent to the roadway. As utility design was not included in the scope of work, utility relocations were addressed in the bid document. 

Coordination was also required with Fort Hill Natural Gas, Charter (TWC), and AT&T. Duke Energy concluded no conflicts, but the lines could be sleeved/shielded. As there were constructability concerns with this option, Duke was contacted for possible relocation of these lines. Information was provided in the bid document for the contractor to coordinate with Duke on the preferred option. Both Charter and AT&T are attached to Duke’s poles and they would relocate, if required. Fort Hill Natural Gas line will remain in place with no impacts.

The bridge was designed to accommodate the underground utilities. The piles and reinforcing steel were located to avoid the utilities. In addition, the two pile caps, 2’-6” and 3’-3” depths, were designed to allow the sewer line to be sleeved within them. The bridge wing walls were also designed to accommodate an existing closed drainage system, upstream of the new bridge, and the replacement of an existing junction box with a new 48”x96” junction box and two 36” SWP which discharge under the bridge.

RESPONSIBILITIES: As a major sub-consultant, J. Bragg Consulting, as Project Engineer and Design Lead, provided the roadway and drainage design, erosion & sediment control plans, other project/plan details and sheets, project specifications and supplemental technical specifications, construction cost estimate, SC DHEC Notice of Intent for land disturbance, right-of-way exhibit, and coordinated with the subconsultants on their respective tasks.