Northpark Entry Plan Balances Flood Mitigation, Saving Trees, Cost

Social media has been abuzz this week about the Northpark Drive entry to Kingwood. As contractors removed trees from the north side of the road to make room for a detention pond, many people complained.

But it’s important to remember why we’re improving Northpark: to accommodate increased traffic and to create a reliable, all-weather evacuation route. In that regard, the Lake Houston Redevelopment Authority (LHRA) must balance three conflicting needs: flood mitigation, saving trees and cost. Let’s look at how each relates to the objectives.

Reliable, All-Weather Evacuation Route

During Harvey, Hamblen Road, Kingwood Drive and Northpark were all blocked by rising floodwaters. That forced many people to try to snake out of Kingwood through Porter…if they could get there. Many couldn’t.

For decades, we’ve also worried about the possibility of a train disaster that could block off Kingwood’s exits. The longer trains that Union Pacific runs now can block multiple exits simultaneously. The longest trains stretch for more than three miles. And if there were a derailment or toxic spill, it would be difficult getting people to safety.

Raising the elevation of Northpark between Bens Branch and the Kingwood Diversion Ditch eliminates the first problem. And building the bridge over the tracks at 494 eliminates the second.

Finally, widening the road will enable more vehicles to evacuate faster.

Flood-Mitigation Enhancements

All that extra concrete to expand the road, however, reduces rainwater infiltration and increases runoff. To keep the road from flooding, engineers calculated they needed 22 acre feet of stormwater detention capacity near US59.

The solution: build two permanent ponds, one each on the north and south sides of 59 where the groves of trees were. TxDoT already owned the land. So it was available at no cost.

*Looking N toward Kroger Center. Clearing for N pond completed. Clearing for S pond (bottom right) begins next week.*

Water will permanently fill the ponds, just like those at Kingwood Drive. The difference between the normal water surface elevation and the lip of the ponds will equal 22 acre feet. The size of the ponds will keep that gap at an aesthetically pleasing level.

*Looking S*. *Note the protective fencing around the remaining trees. Additional trees may be stored temporarily in the foreground.*

Said another way, the ponds will look like decorative enhancements but serve a vital purpose that few realize.

The outline you see in the photo below will match the perimeter of the pond.

*No more trees will be cut for this pond. The area cleared represents the final outline of the pond.*

The layout below shows how the ponds should look when completed.

*For a more legible, high-res version, click here.*

Saving Trees

According to Ralph De Leon, project manager, “Enough trees will remain to form a pleasing backdrop for the pond, screen the visually noisy area behind them, and create a good first impression for visitors.”

*From 30 feet, you can barely see the shopping center behind the trees. From ground level, it will be completely screened.*

It’s important to remember that when KSA revised the Kingwood entries after TxDoT widened 59, many people wanted ponds at Northpark. They complained that KSA was neglecting Northpark compared to Kingwood Drive.

Many trees are being transplanted. But that’s an expensive proposition; the trees have grown since LHRA first prepared estimates two years ago.

“We’ve already identified the trees that will be saved,” De Leon continued. “Some will move to their permanent location immediately. Others will be stored temporarily at staging locations until the road construction gets further along. Then they’ll be moved to their permanent positions.”

The landscape architects, contractor, and LHRA are evaluating each tree individually. Their objective is to save as many as possible. But dollars pose a constraint.

Cost Limitations

De Leon also says “The cost to move each tree is roughly $11,000. We can’t afford to move the truly huge trees. They cost up to $100,000 per tree. And we just don’t have a budget for those.”

*Machines like these will move trees that range from 4″ to 17″ in diameter.* *Photo courtesy of Davey Tree Company*.

To maximize aesthetics, the Redevelopment Authority will relocate a mix of trees, such as oaks and pines.

*The trees that will move have already been inventoried and tagged.*

Update on Water-Line and Utility Conflicts

In my last Northpark post, I pointed out two conflicts holding up construction of the median farther east – one with a water line to a new church near Russell-Palmer Road and a second with CenterPoint.

The City of Houston has agreed to let the Redevelopment Authority’s contractor design a workaround for the water line that interfered with the placement of box culverts. Contractors left a gap big enough for two sections of culvert and a coffer dam to keep dirt from collapsing into the hole.

Because the culvert is tongue-in-groove, contractors also left enough room for a collar. That will allow the two new sections to slide into place. It will also prevent leaks in any gap that remains.

Regarding the CenterPoint gas line running down the center of the ditch at different depths, CenterPoint decided to move the whole line out of the culvert to the south side of the road. Inbound drivers may notice long lengths of welded blue pipe stacked up between Russell-Palmer and Kings Mill. That’s what that is for.

Next Steps

Contractors will start removing trees for the south entry pond at 59 during the week of 9/24/23. Here is the latest revised schedule. Check back often for more updates as they happen.

Posted by Bob Rehak on 9/23/23

2216 Days since Hurricane Harvey