More Drainage for Northpark Drive Expansion Project

The drainage project currently underway down the median of Northpark Drive represents only part of the drainage improvements for the expansion project. Another parallel drainage system about 250 yards north of Northpark will carry additional stormwater all the way from U.S. 59 to the Kingwood Diversion Ditch and Bens Branch. Project engineers call it “Ditch One.”

Additional Parallel Drainage Route North of Northpark

In the satellite image below, the two triangles at 59 surround the wooded areas at the Northpark entrance to Kingwood. Detention ponds similar to those at the Kingwood Drive entry will replace those wooded areas.

The water surface elevation of the Northpark ponds will be several feet below grade, as you can see in this video.

The difference between the surface of the ponds and ground level will provide storage capacity to offset the increase in impervious cover created by the expansion of the roadway.

When the south pond fills up, it will overflow to the north pond. And when the north pond fills up, it will drain to the east (right) via an eight-foot culvert. The eight-foot culvert by itself provides additional underground water storage before it reaches the eastbound ditch.

That culvert will go under Loop 494 and the UnionPacific railroad tracks, then turn left (north) until it gets past the businesses on the north side of Northpark. From there, it will empty into a ditch that heads back east again. See below.

Ditch One is barely visible in the photo above for two reasons.

• The tree canopy is dense this time of year.
• Due to lack of maintenance over the years, trees have grown up in the ditch. Contractors will have to clear them out to restore conveyance before completion of the project.

The Big Split

Once water in the ditch reaches the detention basins south of St. Martha Catholic Church, part of the water will enter the Kingwood Diversion Ditch and head south along the western edge of Woodland Hills. The rest will continue east and go down Bens Branch which angles diagonally toward Town Center and eventually reaches Lake Houston near Kings Harbor.

Why Diversion Ditch is Called Diversion Ditch

The split you see in the red line below is why the Diversion Ditch is called the Diversion Ditch. It is a man-made channel designed to take some water out of the natural channel (Bens Branch) to reduce flood risk for homes in the center of Kingwood.

In the photo above, Bens Branch flows R to L. The Diversion Ditch flows south toward Kingwood Drive and Lake Houston. The blue water towers in background are near the firehouse on Kingwood Drive and Deer Ridge Park.

The City just finished cleaning out under the Northpark bridges at the Diversion Ditch. See results below.

Eventually, the Diversion Ditch itself will expand to match the increased conveyance you see under the bridges. Ralph De Leon, project manager for the Lake Houston Redevelopment Authority/TIRZ stated during an interview that constrictions like you see above contributed more to flooding than lack of capacity in the ditch itself.

After reaching a certain height, water struck bridges and backed up, spilling over into neighborhoods.

Kingwood Drainage Priorities

Regardless, expansion of the Diversion Ditch was one of the top two priorities of the Kingwood Area Drainage Analysis. That project has not yet started.

Bens Branch has already gone through four phases of de-silting and de-snagging to help restore its conveyance. That was part of a major maintenance program by HCFCD after Harvey.

The route that Bens Branch will take to get under Northpark Drive east of the diversion ditch has yet to be determined. However, that phase of the project is still at least three years away. TxDoT is currently evaluating multiple alternatives suggested by engineers for the Lake Houston Redevelopment Authority. For more videos of the project, drainage studies and construction plans, see the LHRA website.

Posted by Bob Rehak on 8/17/2023

2179 Days since Hurricane Harvey

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