SOUTHWESTERN PARKWAY CSO BASIN CONSTRUCTION

Project Location: Louisville, KY

Owner: Louisville Metropolitan Sewer

GC: Ulliman Schutte

Engineer: Burgess & Niple

Project Revenue:  $700,000.00

Project Timeline: September 2017 – June 2018

The Challenge:

The Southwestern Parkway CSO Basin is in middle of the historic Shawnee Park, near the Ohio River, where existing pump stations are located. The new storage basin and pump station is 490 ft. x 220 ft. x 55 ft. deep. The upper 25 ft. of clay soils are underlain by medium to coarse sand, clay and granular soils to 65 ft. below ground where a dense clay layer begins. These coarse, granular soils contain a high volume of groundwater.

The Solution:

The area was benched down 18 ft. to allow interlocking sheeting to be installed to a depth of 70 ft. and toed into the clay layer creating a “bathtub”. Griffin installed a series of wells inside the sheeting, but a series of leaks was discovered in the sheeting as excavation proceeded. Griffin then installed a series of wellpoints along the sheeting on the southeast corner and along the east side of the excavation to obtain the required drawdown and intercept the groundwater that was leaking into the excavation. Due to the proximity to the river and the depth of the excavation, additional wells were needed to control hydrostatic pressure. Griffin installed another six (6) jetted deep wells to handle the excessive flows coming through and under the sheeting. The two wellpoint systems Griffin designed each had fifty wellpoints jetted down to 20 ft. and each system had an 8-inch wellpoint pump. The dewatering flows from inside the excavation were up to 3,500 GPM to allow the Contractor to excavate and pour the concrete foundation.

The Griffin Difference:

Griffin mobilized crews as soon as possible, most of the time within 2 business days, to modify the system to accommodate the changing site conditions. Griffin’s engineering department designed the right solution with the required high flow-rate to properly manage the groundwater during construction.