THE SOLUTION

EAST (GUITAR) TOWER

Griffin dewatered for the 70 ft. x 50 ft. sheeted foundation and elevator core utilizing nine (9) deep wells. The original plan called for six (6) deep wells; however, the foundation was within a lake that was previously backfilled and compacted causing the permeability of the soil and production of the wells to vary from one side of the excavation to the other. During installation a pump test was conducted. The site specific data was used to update the original design model to determine the likely impact of the planned dewatering system. The updated model showed that additional flow (and wells) would be necessary to accomplish drawdown. All wells were installed to ±40 ft. The entire system pumped approximately 650 gallons per minute (GPM) and provided water level drawdown to approximately 20 ft. below ground surface for the 4-month duration of the dewatering system operation.

POOL TOWER

The pilecaps for this structure required wellpoint dewatering of two (2) separate sheeted foundation areas with a total perimeter of 800 linear ft. The water level was maintained approximately 12 ft. below grade for the 3-month duration of the dewatering system operation.

EAST POOL PAVILION BASEMENT LEVEL

The basement level of this structure required wellpoint dewatering of a total sheeted perimeter of 500 linear ft. The water level was maintained at approximately 19 ft. below grade for the 4-month duration of the dewatering system operation. A supplementary wellpoint system was installed in the base of the excavation to dewater one (1) deep elevator pit.

POOL EQUIPMENT BASIN

The subsurface pool equipment room required wellpoint dewatering of a total perimeter of 300 linear ft. Approximately 100 ft. of the excavation was completed by open cutting and the remaining 200 ft. was sheeted. The water level was maintained approximately 15 ft. below grade for the 4-month duration of the dewatering system operation.

VALET TUNNEL

Griffin dewatered for the 650 linear ft. tunnel to move cars between the casino entrance and the parking garage. The original plan called for seventeen (17) deep wells. Once construction began a pump test was completed. This information was utilized to update the original design model to determine the anticipated performance of the planned dewatering system. It was determined that additional drawdown would be needed at the major utility crossing at the deepest point of the tunnel. To obtain the required drawdown, two (2) wells were added and well spacing was modified to maximize drawdown throughout the tunnel. All wells were installed to ±40 ft. The entire system pumped approximately 2,000 GPM and provided water level drawdown to approximately 20 ft. below ground surface for the 6-month duration of the dewatering system operation.

OCULUS BASEMENT

This basement feature required wellpoint dewatering of the sheeted excavation with a total perimeter of 320 linear ft. This feature was added partway through construction as a change to the original scope. Dewatering of hallways leading to and from basement (60 linear ft. each) was also included, as was dewatering at the tie-in to valet tunnel. The water level was maintained approximately 15 ft. below grade for the 3-month duration of the dewatering system operation.