To make way for the new $60-million Ritz-Carlton Charlotte at the Bank of America Corporate Center in downtown Charlotte, NC, the water cooling lines of the Bank of America Corporate Center and Founders Hall needed to be relocated under the adjacent College Street — a busy four-lane road.
The new utilities will be located in an underground 60-in. (152 cm) diameter casing bore (installed using a jack and bore system) that is 64-ft. (19.5 m) long, reaching from curb to curb on College Street.
The Ritz-Carlton Charlotte is being built by the Ritz-Carlton Hotel Company, LLC and Bank of America. It will be developed by Colgate Development LLC with the design created by the architectural firm of Smallwood, Reynolds, Stewart, Stewart and Associates. Preliminary plans for the contemporary-style building include 120 deluxe rooms and 30 suites, a 9,000-sq.-ft. Grand Ballroom; 3,000-sq.-ft. Junior Ballroom; two smaller meeting rooms and a 600-sq.-ft. board room. The health club and indoor swimming pool will be on the roof of the hotel. Other features will include a boutique spa and retail shops. The hotel is scheduled to open in late 2008.
Primary contractor for the Ritz-Carlton project is Bovis Lend Lease; however, Matthews Construction Company of Rockhill, NC, was subcontracted to handle a portion of the first phase of the construction.
According to Jimmy Matthews, owner and president of Matthews Construction Company, the company is responsible for the excavation, shoring, trenching, concrete vaults, demolition of the existing asphalt and landscaping, the curb and gutter work, and the jack and bore work.
Before the pit for the boring equipment could be dug, ESP Associates of Charlotte, NC, located the existing utilities using soft dig equipment in which airflow from an ESP vacuum high-pressure airline gently pushed the dirt aside and the vacuum sucked it up. This was used to avoid damaging the utilities.
After all the utilities were located, Matthews used a Cat 330 hydraulic excavator to dig the pit and a Cat 950 wheel loader to carry the excavated dirt to stockpiles.
Coble Trench Safety of Charlotte, NC, was brought in to prepare a safe enclosure for the boring machine. Richard Overman, safety specialist with Coble Trench Safety, assisted Matthews’ employees in constructing the slide rail system.
Coble Trench Safety (CTS) rents, services and sells trench safety equipment and other specialty products for the underground construction industry; specializing in trench shoring and shielding equipment, confined space equipment, steel road-crossing plate, pipe lasers or pipe plugs and test equipment.
To aid in the safety and productivity in the trenches, CTS provides training in trench and excavation safety including introduction to trench and excavation safety, the OSHA excavation standard, protective systems, soil mechanics and soils analysis, job planning and confined space identification/requirement overview. Through videos, slides, and in-class exercises, the one-day training classes provide continuing education and expertise to the underground industry.
Building the Jack and Bore System
According to Overman, the CTS slide rail system used a 12-ft. (3.7 m) wide pile chamber in the center that allowed the boring access to the trench. This was a dig and place installation that minimized loss of material during the excavation.
The slide rail system consisted of two rails placed in a total of eight 24-in. (61 cm) holes. These rails held the panels of the three-sided slide rail system which was 35 ft. (10.6 m) wide, 40 ft. (12 m) long, and 17 ft. (5 m) deep — big enough to accommodate the 60-inch (152 cm) jack and bore operation. Installation of the slide rail system took three days.
Equipment required to install the slide rail system included a 70-ton (63 t) Link-Belt hydraulic truck crane, which was used to set the 5,500-lb. panels, and a Cat 330 hydraulic excavator, which was used to push the panels into place.
Sanders Utility Construction of Charlotte, NC, used an American auger boring machine to concurrently drill the 5-ft. (1.5 m) bore and push the casing in.
“Encountering old foundations along with the H-beams and cables from the old shoring systems when Founders Hall was built was a challenge during the boring process,” said Matthews. “However, when this happened, we simply removed the obstruction and continued boring.”
Installation of Pipes
MCC Mechanical LLC, of Charlotte, NC, is in the process of installing two 20-in. (51 cm) diameter steel pipes that will carry the cooling water from the basement of Founders Hall to the Bank of America Corporate Center parking garage where the cooling towers are located. Matthews has installed two 12-by-12-by-7-ft. (3.7-by-3.7-by-2 m) pre-cast concrete vaults to house the valves for the water lines on the parking deck side of College Street.
Moore & Son Electric Inc. of Charlotte is in the process of installing the conduit duct to carry the electrical lines from Founders Hall under North College Street to the Bank of America Corporate Center Parking Garage. Matthews has installed two 5-by-6-by-7-ft. (1.5-by-1.8-by-2 m) junctions for the electrical lines also on the parking deck side of College Street.
Matthews has averaged 15 workers at the job site daily. Their contract, which began in early June, should be finished by the end of July. CEG