Aggregate Technologies was the contractor of choice when a contractor needed to remove two Interstate 40 bridges spanning Shell Lake and Blackfish Lake in eastern Arkansas, just west of Memphis, Tennessee.
ATI was involved in the early stages of the project and worked with the Project Manager and engineers to develop a demolition plan based on the lifting capacities of the crane and barge to be used. The weight of each piece of concrete to be removed was calculated which determined the cut locations.
The bridges were about two miles apart and were built using different foundation types. One bridge had pile bents with five 20″ octagonal piles under each bent cap that were driven in place, and the cap was then formed and poured over the piles. One of the old bents interfered with the placement of one of the new bents so it had to come out early in the construction process. ATI operators wire sawed the cap at two locations. They then used a hydraulic automatic gated shear to cut each pile under the cap to allow the crane to lift off the cap sections and place them on a material barge. Due to the proximity of the old piles to the new bent location, the old ones were then pulled using a vibratory hammer/extractor. In many cases pulling the piles is too difficult and time consuming, but ATI has the equipment to cut them off at or below mudline if required.
The second bridge had pier bents with a web wall that joined the two piers together at the bottom half and a bent cap on the top. Each pier bent was systematically wire sawed from the top down to the riverbed, which was 15’ below the waterline. The first cuts were made on the cap so it could be removed in safe manageable pieces, then the piers were sawed off just above the web wall.
Commercial divers had previously drilled pilot holes thru the web walls at the desired wire saw cut locations at the riverbed on all the bents prior to ATI’s arrival. Doing this pre-arrival work eliminated any standby time by operators or divers.
Once the upper half of the piers were removed the web wall was removed by running the diamond wire saw through the pilot holes at the bottom and pulling the wire upwards to the surface. After all the vertical slices were completed the divers placed our transition bracket at the cut elevation and a horizontal cut was made to free each section of the wall. As the wire traversed under each piece of web wall the crane lifted it off and placed it on the material barge to be transferred to shore at the end of the workday. Upon completion of the first bent it was on to the second bent where the process was repeated and so on, until there was no evidence of there ever having been a bridge there.
With Aggregate Technologies diversified and unique selection of equipment – either purchased or invented and manufactured – they can tackle any project above or below the water and even below the seabed. For any inquiries to Aggregate Technologies regarding their underwater cutting capabilities contact the office in Houston at 1-877-SLABSAW or Greg Major 281-753-1105.