Great news! Tuesday, Harris County Commissioners Court approved a $700,000 contract with Neel-Schaffer, Inc. for a Kingwood Area drainage study. The engineering firm will identify flooding sources in the Kingwood area and develop potential solutions.

Data shows that portions of Kingwood have potential for significant offsite flows from Montgomery County as well as ponding locations due to inadequate overland flow conveyance. Said another way, new upstream development is taxing Kingwood’s drainage infrastructure. This project will help ensure that a 100-year flood plain remains a 100-year flood plain, and doesn’t turn into a 10-, 20- or 50-year flood plain.

Drainage Study Details Outlined in Contract

The contract for the work indicates its scope and details. Discussion of those begins in Appendix A on page 14. The goal of the study is to identify mitigation strategies that will return 12.4 miles of existing drainage ditches and streams within Kingwood to their originally designed 100-year service levels.

Agreement with TIRZ 10

TIRZ 10 is a Tax Increment Reinvestment Zone established in Kingwood at the time of annexation. The TIRZ provided a replacement financing mechanism for water, sewer, drainage costs for the development of residential subdivisions once the MUDs were dissolved.

Harris County Flood Control District (HCFCD) entered into an interlocal agreement with TIRZ 10 (Kingwood) to perform a drainage study of five main Kingwood streams to their confluence with the West and East Forks of the San Jacinto River. The five include:

• G103-33-00 Bens Branch – From Rocky Woods Drive to WFSR (Length= 3.1 miles)
• G103-33-01 – From North park Drive to the confluence with Bens Branch (Length= 1.3 miles)
• G103-38-00 (Kingwood Diversion Ditch)- From Harris County Boundary to WFSR (Length = 4.0 miles)
• G103-80-01 (Green Tree Ditch) – From Woodland View Dr to the EFSR (Length= 1.5 miles)
• G103-80-03.1B (Taylor Gully)- From Harris County Boundary to Whiteoak Creek (Length= 2.5 miles)

Flood Control Will Fund Remainder of Streams/Ditches

In addition to the interlocal agreement, Harris County Flood Control District will also study all remaining streams and ditches within the Kingwood Area. Those include another 19.9 miles:

• G103-33-00 Bens Branch – From Harris County Boundary to Rocky Woods Drive (Length = 2.2 miles)
• G103-33-02 – From North park Drive to the confluence with Bens Branch (Length= 0.2 miles)
• G103-33-03 – From Hidden Pines Dr. to the confluence with Bens Branch (Length= 0.1 miles)
• G103-33-04 – From W Lake Houston Pkway to the confluence with Bens Branch (Length= 1.2 miles)
• G103-36-00 (Bear Branch)- From Woodland Hills Dr. to WFSR (Length= 2.7 miles)
• G103-36-01 – From Woods Estates Dr. to the confluence with Bear Branch (Length= 0.8 miles)
• G103-36-02 – From Woodland Hills Dr. to the confluence with Bear Branch (Length = 0.9 miles)
• G103-36-02.1- From Kingwood Dr. to the confluence with Bear Branch (Length= 0.4 miles)\
• G103-36-03- From Royal Circle Dr. to the confluence with Bear Branch (Length= 0.4 miles)
• G103-38-01- From Laurel Springs Ln. to the confluence with Kingwood Diversion Ditch (Length= 1.3 miles)
• G103-38-01.1- From Red Oak Terrace Ct. to the confluence with Kingwood Diversion Ditch (Length = 0.4 miles)
• G103-38-02- From Harris County Line to the confluence with Kingwood Diversion Ditch (Length= 0.7 miles)
• G103-39-00- From Palmetto Ln. to the WFSR (Length= 1.3 miles)
• G103-41-00 (Sand Branch) – From Sycamore Creek Dr. to the WFSR (Length= 2.0 miles)
• G103-41-01- From Elk Creek Dr. to the confluence with Sand Branch (Length= 0.8 miles)
• G103-45-00- From Trail Tree Ln. to the WFSR (Length= 0.4 miles)
• G103-46-00- From Forest Cove Dr. to the WFSR (Length = 1.0 miles)
• G103-46-01- From Sweet Gum Ln. to the confluence with G103-46-00 (Length= 0.7 miles)
• G103-80-01.1- From Autumn Sage Ln. to the confluence with Green Tree Ditch (Length= 0.3 miles)
• G103-80-03.1A (Mills Branch) – From Same Way to Whiteoak Creek (Length = 1.5 miles)
• G103-80-04 (Blackland Gully) – From Maple Knob Ct. to the EFSR (Length = 0.6 miles)

For a map showing the location of these numbered ditches/streams, click here.

Stakeholder Meetings Part of Plan

The scope of work includes several stakeholder meetings with TIRZ 10, homeowner associations, and the community at large. Their purpose: to increase public awareness and understanding of the magnitude of the watershed problems, their complexities and the cost of solutions.

Drainage Study Data Acquisition Phase

The contractor will start by collecting all available information and data including:

• Construction plans
• Previous drainage studies
• HCFCD historical flooding data
• High Water Marks
• Watershed Masterplan data
• FEMA Repetitive Loss properties
• Flooding reports
• LiDAR DEM data
• Aerial maps
• HCFCD watershed maps
• Hydrologic and hydraulic models
• City of Houston GIMS data
• Any other pertinent technical data in the development of this scope of services.

Field Reconnaissance Phase

Neel-Schaffer engineers will then conduct field reconnaissance of the existing drainage systems, outfalls, and drainage patterns within the project area. That will include field measurements of 27 bridge crossings, 32 culvert crossings, 16 pedestrian bridge crossings and 6 drop structures to be incorporated in the development of hydraulic models.

During this stage, Neel-Schaffer will also measure high water marks; update floodplains; and analyze stream performance and capacity to illustrate flooding issues to the County, TIRZ and community.

Identification of Structural and Non-Structural Mitigation Alternatives

The Engineer will determine structural and non-structural improvement alternatives to bring all streams back up to the 100-year level-of-service.

Neel-Schaffer will perform this analysis using full conveyance at peak flows. Engineers will identify the major constraints that affect the available solutions for each stream.

They will then consider both structural and non-structural alternatives for mitigation.

Structural Alternatives

Structural alternatives include:

• Improved drainage channels including widening, deepening, and/or lining for increased conveyance capacity.
• Watershed diversions using enclosed conduits (following existing roadway alignments or other public ROW).
• New regional or sub-regional detention basins and modification of existing detention basins including inlet and/or outlet structures.
• Enhanced conveyance using selectective clearing and re-shaping of natural channels.
• Enhanced flood storage in natural and park areas using small-scale berms and grading.

Non-Structural Alternatives

Non-Structural Alternatives include:

• Property buy-outs.
• Coordinated ROW dedications for future improved channels and regional detention basins.
• Regional detention fees for new development.

Drainage Study Will Consider Detention Ponds

This contract includes identifying detention needs, identifying potential locations, and developing schematic layouts of the detention ponds. It also includes:

• Proposed Right of Way acquisition
• Preliminary Cost Estimates
• A project priority and implementation plan

It is not clear at this point how long this project will take.

This post is dedicated to Barbara Hillburn, the president of the Kingwood Lakes HOA, who fought long and hard to get a project like this started. Thank you, Barbara!

Posted by Bob Rehak on 8/14/2019 with thanks to Barbara Hillburn and Precinct 4 Commissioner Jack Cagle

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