Project Highlights

ACEC/SC Engineering Excellence Award

The project consists of 33 miles of alignment between US 17 in North Myrtle Beach and US 501 near Aynor, South Carolina. The alignment spans the Atlantic Intracoastal Waterway in North Myrtle Beach and the Waccamaw River near Red Bluff, South Carolina. There are also numerous wetland trestles. There are a total of 42 bridges with an overall length of about five miles. There will also be long stretches of embankment over swamplands.

Phase I of the project consists of six lanes between US 17 and SC 90, and two lanes from SC 90 to US 501. Total fill volume is approximately 8.7 million cubic yards. Under a contract with Fluor Daniel Infrastructure, S&ME has been performing work on Phase I since June, 1998. Phase II includes widening of the two-lane portion to four lanes.

All 42 bridges are supported by precast concrete piles up to 100 ft. long. There are 29 trestles constructed of precast caps and post-tensioned decking. Twelve of the remaining bridges feature cast-in-place columns, caps, diaphragms and overhangs with AASHTO girders. S&ME provided an on-site laboratory for testing of all concrete poured on the project. Tensile and elongation testing was performed on samples of all steel reinforcing used at our metallurgical laboratory in Knoxville, TN. The on-site laboratory was inspected and approved by the SCDOT Research and Materials Laboratory prior to startup. Peak production required 21 on-site inspectors and technicians at the project and 5 at off-site fabrication yards.

S&ME responsibilities are summarized below:

• Observe undercutting or stabilization of embankment subgrades

• Observe placement of structural fill and perform soil density tests

• Pre-pour inspection of precast and cast-in-place concrete formwork and sampling of plastic concrete

• Observe asphalt laying operation and sample asphalt pavement

• Conduct acceptance tests of construction products

Half of the project length falls in swampland. S&ME engineers were present in all fill areas to approve subgrade prior to placing new fill. In many cases, undercutting was reduced or eliminated by use of geogrid stabilization or similar measures. Long Bay was spanned in four weeks over a 4,000-foot distance. S&ME technicians witnessed fill placement and performed field density tests at prescribed intervals. Borrow pit production was monitored daily and frequent classification and plasticity tests were performed.

Precast concrete piles up to 100 feet long support all 42 bridges. There are 29 trestles constructed of precast caps and post-tensioned decking. Twelve of the remaining bridges feature cast-in-place columns, caps, diaphragms and overhangs with AASHTO girders.

S&ME provided an on-site laboratory for testing of all concrete poured on the project. Tensile and elongation testing was performed on samples of all steel reinforcing used at our metallurgical laboratory in Knoxville, Tennessee. The on-site laboratory was inspected and approved by the SCDOT Research and Materials Laboratory prior to startup. During 1999 S&ME provided at least 16, full time, on-site technicians on this project.