Woodridge Village Excavation and Removal August

Woodridge Village Excavation Slows in July

During July 2023, Harris County Flood Control District (HCFCD) contractor Sprint Sand and Clay, LLC, excavated 5,754 cubic yards from a new Woodridge Village stormwater detention basin. That brought Sprints’ grand total up to 135, 751 cubic yards. 

5,764 cubic yards equals another 3.6 acre feet. The previous month, Sprint excavated 5 acre feet. So, excavation during July declined 28%. At the current rate, Sprint would take another 8 months to bring detention volume up to Atlas-14 requirements (see table below). 

At the end of July, excavation had reached 92.6% of Atlas-14 requirements, up slightly from June, when it had reached 92%. 

Why Atlas 14 is Important

Atlas-14 defines the current standard for safely containing a 100-year rainfall. The lack of detention basin capacity contributed to the flooding of hundreds of homes along Taylor Gully twice in 2019, after Perry contractors clearcut the property.

HCFCD and City of Houston purchased the property from Perry in March 2021. Excavation of additional stormwater detention capacity started in January 2022. At the time, it had only 70% of the required detention capacity under Atlas 14.

NOAA is already working on revising Atlas 14. Atlas 15 will incorporate predicted climate-change impacts and feature recurrence intervals up to 1000 years.

However, the good news is that Sprint’s contract could eventually take the site well beyond Atlas-14.

Before/After Photos Show July Progress

I took the first photo below on July 1, 2023.

Woodridge Village E&R as of July 1, 2023
Woodridge Village July 1, 2023, looking NE.

I took the other photos below at the end of July.

July 29, 2023. The big difference appears to be the area filled with water.

The outline has changed little. But additional water in the absence of rain and the presence of blistering heat suggests excavation may have reached the water table.

During the month of July, when temperatures pushed a 100 degrees every day, the nearest gage received only 2 inches of rain. And most of that was three weeks before the photo above.

HCFCD often prefers wet bottom retention basins because they reduce mowing costs, but the design of this basin is not yet complete.

Those circular patterns may indicate the use of scrapers to lower the bottom of the new basin gradually.
However, north (right) of the exposed water, contractors still seem to be using excavators to expand the edges of the area.

Under HCFCD Excavation and Removal contracts, contractors are free to excavate where they want within the provided footprint.

Rough layout for new Woodridge basin.
Green area indicates rough outline of new basin.

Where Does Woodridge Village Excavation Go From Here?

HCFCD’s Excavation and Removal contract with Sprint Sand & Clay calls for excavating up to 500,000 cubic yards. Sprint excavated approximately 8,000 cubic yards (5 acre feet) in June. 

Any excavation beyond Atlas-14 needs would create a safety hedge against future needs should they increase. 

NOAA is already working on updating the Atlas 14 requirements and should release Atlas 15 before the end of this decade.

Here’s how the various stages look in a table.

Acre Feet of Stormwater Detention% of Atlas-14 Requirement% of Ultimate
Site Had When Purchased from Perry Homes27170%47%
Has as of 8/1/23356.592.5%61.5%
Atlas 14 Requires385100%66%
If Sprint Excavates All 500K Cubic Feet580150%100%
Calculations based on original construction plans, HCFCD monthly reports, Atlas-14 Requirements and Sprint contract. Sprint could excavate down to or even slightly past the small grove of trees in the top center.

Sprint will make only $1,000 from its Woodridge Village excavation contract with HCFCD, but will make its profit by selling the dirt at market rates. It’s a good deal for taxpayers, but carries some uncertainty with it.

If the demand for dirt dries up, excavation could slow or stop.

But simply excavating the dirt isn’t the end of the job. Harris County still needs to slope the sides, plant grass, and tie the new basin into the site’s existing stormwater-detention-basin network. Engineers are reportedly working on plans for all that, according to HCFCD.

Posted by Bob Rehak on 8/1/2023

2163 Days since Hurricane Harvey