This project, located along Channel 3 at the western edge of the Sienna South levee system, adds another 270,000 gallons per minute of pumping capacity (in addition to Phase 1) to the system during a Brazos River event where gravity drainage from the levee system has been cut off. This phase consists of 6 pumps each capable of pumping 45,000 gpm. This project brings the total pumping capacity of Pump Station No. 4 (along with completed Phase 1) to a total of 540,0000 gallons per minute. Along with Pump Station No. 2 in the south the total pumping capacity after completion of Pump Station No. 4 Phase 2 will be 800,000 gallons per minute. The ultimate total pumping capacity of the south levee system will be 1.2 million gallons per minute.
This project was required due to the Fort Bend County Atlas 14 criteria. In order to release the increased conveyance flows, a new outfall structure was required along Channel 3 just downstream of Pump Station No. 4. This structure consists of 6 – 10’ x 10’ box culvert barrels through the levee and a second major drainage channel outfall to the Brazos River. This project was designed to take advantage of available discharge elevation energy gradient that will allow increased flows to be discharged outside the levee during gravity flow events.
This project was required due to the increased stormwater flows dictated by the Fort Bend County Atlas 14 criteria. This new pipe culvert will drain increased flows from the Southern Colony detention pond located just east of FM 521. The culvert will be bored under FM 521 and discharge to the SPLID internal Main Channel at the confluence of Channel 1. This additional 66” pipe culvert will supplement the already existing 30” discharge pipe.
This project will improve working areas and access to Pump Stations 1 and 3 in the north and Pump Station 2 in the South. Improvements include adding concrete pavement access, crushed stone working areas, concrete gator pump slabs, enhanced levee access and access ladders for pump station wet wells.
The 104-lot development located off Bees Passage just west of Sienna Parkway was designed to store stormwater events in 5 lakes during Brazos River events. This project will convert the Major Drainage Outfall at the southern end of Happy Hollow Lane into a 40,000 gallon per minute pump station that will supplement the existing lake storage during Brazos River events. This project will allow pumping operations to be sustained throughout the event in order to keep internal water levels as low as possible and street ponding to a minimum.
This project will add lighting packages at all major outfalls located within the Sienna levee system. This project also includes establishing permanent Center Point 3-phase power to all of the back-up sluice gate motors that were installed in 2019. The locations of these projects include the North Pump Stations 1 and 3, South Pump Station 2, South Pump Station Outfall Structure, Oyster Creek and Long Point Creek North Outfalls, Oyster Creek South Outfall, Outfall No. 2 at the end of Channel 3-3 and the GCWA Sienna Parkway Structure.