Silverdale Creek Improvements

Conroe, Texas

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Costello prepared Drainage Impact Studies, Conditional Letter of Map Revision (CLOMR), Letter of Map Revision (LOMR) submittals, and PS&E documents to construct channel and detention pond improvements for this 285-acre tract located in the City of Conroe, Texas. The project was completed in two phases to match development patterns in the area and to provide sufficient time to complete permitting through the City, TxDOT, Union Pacific Rail Road, USACE, and FEMA.

The first phase of work encompassed approximately 50 acres, including the main stem of Silverdale Creek. The existing channel was expanded, and two ponds were built to support future development. At the time of the initial study, Costello identified an existing split-flow condition where stormwater diverted to the northbound frontage road of IH-10. The study quantified the flow rate diverted. A USACE Section 404 Permit and FEMA CLOMR and LOMR were approved for the project.

The second phase of work included designing a diversion structure to help manage split-flows from Silverdale Creek. A channel/detention pond system accepted flows and provided mitigation for the loss of floodplain storage, full development of the tract, and the increased conveyance of channelizing the overflow. Wetland areas were identified and preserved in the drainage plan. Fill spoils from the channels and ponds were kept onsite to elevate building pads above the 1% AEP Base Flood Elevations. Design work was coordinated with the City of Conroe to consider a Tree Preservation Ordinance implemented during the project’s design. A CLOMR and LOMR were also prepared for the second phase of work.

For both phases of work, Costello prepared PS&E documents, bid the project for construction, and provided construction phase services.

Relevant Project Services

  • Drainage Impact Analysis
  • 2D Unsteady State Modeling
  • 1D Unsteady State Modeling
  • Surveying
  • Conditional Letter of Map Revision
  • Letter of Map Revision
  • Construction Phase Services

Project Size and Cost

  • 330 acres
  • Estimated cost $3.9M

Unique Project Attributes

  • Pond and channel design preserves environmentally sensitive areas
  • Overflow flow from Silverdale Creek

Challenges Faced

  • Flow split of floodplain along IH-10 and UPRR right-of-way
  • Need to Preserve Environmentally Sensitive Areas

Resolutions & Results

  • Diversion structure constructed to control flows
  • Detention ponds sized to contain flows and support development
  • Channel Thalweg protected and integrated into drainage system design


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