Northpark expansion project

Deeper Dive into Northpark Expansion, Drainage Plans

On 7/27/23, I interviewed Ralph De Leon, Northpark project coordinator for the Lake Houston Redevelopment Authority (TIRZ 10) and Kevin Perkins, a project manager for HNTB, one of the contractors on the job. The discussion covered both the eastern and western phases of the project from Woodland Hills Drive on the east to US59 and beyond on the west.

Since Tuesday, the contractors have made visible progress. Let’s cover that first. Then I’ll cover some surprising facts I learned about the project, including flood-mitigation plans; why the project has taken so long; how it will expand to 10 lanes near the railroad and Loop 494; parts of the project that will be elevated; bridge reconstruction; Atlas-14 conflicts; and more.

Box Culverts Arrive

By mid-day today, contractors had box culverts stacked several blocks in the median between Russell-Palmer Road and Flowers of Kingwood. They also had three excavators working Thursday, compared to one on Tuesday. And they were cutting concrete in the cross-overs.

Looking west from the diversion ditch (foreground). Only the 66″ round concrete pipe by the first excavator was there on Tuesday.
Looking east down the Northpark Drive median in opposite direction. Those rectangular culverts measure 6’x8′.
Note men cutting concrete in the median between Flowers of Kingwood (upper left) and the fireworks stand (out of frame, lower right).

The 6×8 box culverts stacked in the distance will extend under the cross-over and connect to the round concrete pipe using the junction box stacked in front of the four round pipes. See below.

Box culverts were stacked up to the red rib truck in the background.

The box culverts will convey 35 square feet of stormwater compared to slightly fewer square feet for the round pipe.

That “step-down” as stormwater moves toward the diversion ditch will provide inline detention.

Also note that the existing culverts under the crossovers provide even less conveyance/storage than the new pipe. The old pipes were much smaller and frequently become clogged with weeds and grass due to long maintenance intervals.

According to Perkins, the new pipe/culvert solution offers less friction from end-to-end. The pipes shouldn’t become clogged like the old pipes did because grass and weeds won’t grow in them. Also, their consistent dimensions under the cross-overs should let more water pass through faster.

To make sure water can get into the culverts quickly during heavy rains, contractors will use extra large inlets, similar in size to those used on freeways.

Why Project Has Taken So Long

De Leon and Perkins discussed approval delays at length, mostly related to multiple groups giving input and approvals.

  • The project goes into, out of and back into the City of Houston.
  • It straddles two counties, each with different leadership and regulations.
  • A TIRZ, several MUDs, homeowner associations, commercial associations, KSA and Lone Star College are also involved.
  • Harris County Flood Control District is reviewing all the plans and approvals.
  • TxDoT has final say over design criteria.
  • Funding will come from State, Federal, and local authorities.
  • The Union Pacific (UP) Railroad has had multiple changes in leadership since the project started.
  • Gaining utility easements and rights of way has taken much longer than expected. For instance, Entergy wants 50 months to move a SINGLE transformer, almost half again as long as it will take to build the ENTIRE bridge over 494 and the UP railroad tracks.

Getting all those dominos to line up has challenged everyone involved.

Project Will Expand to 10 Lanes Near Loop 494

Where the western phase of the project crosses Loop 494 and the UP railroad tracks, traffic surveys indicate that 80% of the traffic will go over the bridge. Regardless, TxDoT requires two lanes of feeder road in each direction to handle local traffic not going over the bridge. Six lanes of bridge and four lanes of feeder will require some property acquisition still to be completed. Not all of the expansion will fit over the center ditch.

Pedestrian Underpass

The eastern phase of the project will contain a pedestrian underpass similar to others found throughout Kingwood. Engineers hope to keep water out by making the entrances higher than surrounding areas so water drains away. The tunnel will be 10 feet wide to accommodate special extra-wide wheelchairs for people with curved spines. Ten feet will accommodate two such wheelchairs moving in opposite directions.

Elevated Roadway with Cheek Walls

In certain areas that experience repetitive flooding, especially east of the drainage ditch where Bens Branch cuts under Northpark Drive, the road will be elevated. Feathering out the bed toward the sides would require killing hundreds, if not thousands of trees. So instead, contractors will elevate the road using “cheek walls.” Highway 59 makes extensive use of cheek walls for the same reason – to conserve space and allow trees to grow.

Two 10-Foot Sidewalks to Lone Star College

West of 59, contractors will build two 10-foot sidewalks along Rock Creek south of Northpark. The sidewalks will help cash-starved Lone Star College students ride bicycles to class when weather permits. Katherine Perrson, now retired head of the college, made the request.

Leaving Room for Diversion Ditch Expansion

The City has hired a contractor called NBG Constructors to clean out the diversion ditch under both Northpark Drive bridges and return the channel to its original as-designed capacity. Over the years, sedimentation has constricted the flow as you can see below.

Note accumulated sediment constricting flow under bridge.

Eventually, Harris County will widen the diversion ditch. HCFCD rated it one of the two most important projects in Kingwood. As part of the Northpark Expansion project, both bridges will be rebuilt, but with enough width to accommodate eventual expansion of the ditch.

Meets Harris County Atlas-14 Requirements

When complete, the project will meet Harris County Atlas-14 requirements for 77339 which are more stringent (about 40% higher) than Montgomery County’s. That’s because virtually all of the water associated with this project will drain into Harris county. MoCo standards are lower because Montgomery averages requirements across the entire county. Rainfall drops off with distance from the Gulf.

Detention Basins and 59 Entry

To reduce the chance of flooding near 59, contractors will build two detention basins on either side of Northpark at 59. They will connect with each other underground and also connect with another basin and channel north of Northpark via an 8 foot pipe.


All this won’t happen overnight. De Leon is working on updating the timetable and will post it with a new project website that gives Kingwood and Porter residents weekly or bi-weekly updates. More news to follow, including a deeper dive into the drainage analysis and how some water will be diverted around Northpark.

Posted by Bob Rehak on 7/27/23

2158 Days since Hurricane Harvey