Saddle Creek Retention Treatment Basin Project


 

This time lapse video illustrates construction progress at the  Saddle Creek Retention Treatment Basin. The opening perspective is looking southwest from 64th and Arbor Streets and the time lapse covers the period from June 2019 through November 2020. Construction activities occurring on the top half of the screen feature a temporary earth retention system, soil excavation and installation of deep foundations supports. Activities on the bottom half of the screen are occurring in the stream channel and include a new combined sewer diversion structure; two, 120-inch sewers and a new concrete channel liner. The vertical, steel beams you see are known as H-piles. H-piles are commonly used in deep foundations and are driven into the ground to support the structure. This work was completed in April 2020. At the 35 second mark, the camera moves to look northwest at basin construction. You will notice Baxter Arena towards the top of the screen. Construction activities include the concrete slab basin and walls being poured. At the end of the video, the contractor is placing fill material along basin walls. Construction over the next six months will focus on completing the basin exterior walls and interior walls and columns.

 

Schedule

Basin exterior walls are nearly complete. Interior walls and columns concrete pours continue.

  • Early Soils Removal – Q3 2016
  • 66-inch Sewer Install – Winter 2020
  • Basin Concrete – Winter 2020
  • Operations Building – Summer 2021
  • Chemical Building – Summer 2021
  • Substantial Completion – Winter 2023
  • Final Completion – Summer 2023

Cost at Completion

  • Early Soils Removal – $2.2 million

 

Project Description

The purpose of the Retention Treatment Basin (RTB) is to capture combined sewage and store or  treat it during wet weather events. Combined sewage will be diverted from the Saddle Creek Sewer and conveyed to the RTB headworks, where large materials like cans, rocks, tree branches and floatable solids are removed using a grit pit and mechanical screens. Directly following screening, a disinfectant is added to the combined sewage flows to kill or inactivate pathogenic bacteria. For small wet weather events, the combined sewage will be fully captured (retained) in the underground basin.  For larger events, the underground basin will completely fill up and then a dechlorination agent is added just prior to flows discharging through an overflow channel to the creek.

The RTB will use dewatering pumps to empty the facility after a wet weather event has ended. These pumps will convey captured combined sewage volume into the downstream Papillion Creek Interceptor sewer for treatment at the Papillion Creek Water Resource Recovery Facility (PCWRRF).

Above ground improvements include a building to house controls, grit and screening equipment, and chemicals.  The building will provide office space for full-time operations staff, some additional city offices and maintenance for the facility.

An odor control system will be installed to address the risk of odors from the facility. The site will include fencing and lighting for security purposes. Deliveries will occur regularly but are not expected outside of typical business hours.

Over 190,000 tons of soil have been excavated for the construction of the 3.3 million gallon below-ground basin. Once completed, the RTB will capture and treat a combined sewage flow rate of up to 160 million gallons per day.
Steel beams have been driven into the soils below the concrete basin to support the facility’s structure. These 848 steel beams (approximately 13 miles in total) support the weight of concrete, water, soil and other building materials. While 90 percent of the pile driving was completed by May 2020 for the underground basin, additional deep foundation supports will be installed in January 2021 for the above-ground operations and chemical buildings.

The concrete work for the first phase of the channel and diversion structure was completed in early 2020.

Construction from summer 2020 to fall 2021 will focus on placing rebar and concrete pours for the basin. Approximately 25,000 cubic yards of concrete, roughly 2,500 truckloads, will be used to construct the basin and the facility’s walls.

Updated February 2021

Saddle Creek Retention Treatment Basin, Artist's Rendering