Sienna Plantation Wastewater System

Houston, Texas

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Costello provided planning and design to consolidate and regionalize the wastewater collection and treatment system.

Costello designed a new 3.0 mgd south regional wastewater plant that utilizes an advanced membrane bioreactor treatment process, including biological nutrient removal and the ability to capture 100% of the reclaimed water collection/distribution system flow to send to irrigation and pond makeup throughout the development.

South Regional WWTP includes headworks with coarse/fine screening, stacked tray grit separation, teacup solids classifier, four MBR trains, UV disinfection, centrifuge dewatering, and SCADA for fully automated control of plant operations.

Costello also designed a new north regional lift station with force main and modified the south lift station with new force main to reroute flow to the two regional WWTPs from three steel package plants to be decommissioned. 

Costello designed the expansion of the north regional plant (City of Missouri City Steep Bank Flat Bank WWTP) from 3.0 mgd to 4.5 mgd, including conversion of extended aeration to complete mix with nitrification.

Costello coordinated all design work with TWDB and analyzed and recommended improvements to the City’s north collection system.

This project received EPA recognition of a clean water project that demonstrates excellence through the George F. Ames Performance and Innovation in the SRF Creating Environmental Success (PISCES) program. This project also illustrates the cost-saving benefits of the Clean Water State Revolving Fund (CWSRF).

Relevant Project Services

  • Planning and design
  • Collection systems
  • Force mains/gravity sewers
  • Diversions & decommissioning
  • Wastewater treatment plants
  • State/Federal (TWDB) funding
  • Reuse booster pump station
  • Odor control
  • WWTP rehab/expansion
  • Construction phase services

Project Size and Cost

  • North (1.5 mgd ADF) - $8M
  • South (3.5mgd ADF) - $21M

Unique Project Attributes

  • Membrane bioreactor design
  • Full flow capture for reuse
  • Extended aeration to complete mix with nitrification

Challenges Faced

  • Retrofit of Existing WWTP to add 1.5mgd while maintaining 3.0 mgd service w $8M budget

Resolutions & Results

  • Construction complete for majority of work


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