Rapid Runoff from World’s Largest Trailer Park Wipes Out Plum Grove Road in Liberty County and More

Rapid runoff from Colony Ridge, perhaps the world’s largest trailer park, in Liberty County contributed to a washout of FM1010. Nearby residents in Plum Grove say it also contributed to the flooding of their homes. Moreover, erosion from the development has contributed to the buildup of sedimentation in the East Fork.

Nine years ago, this area was mostly forested wetlands. Today, it’s mostly mobil homes, many on barren lots, stretching mile after mile.

World’s Largest Trailer Park?

There is no definitive source ranking the size of trailer parks, but multiple references to Sun Valley in Nevada come up when you Google “world’s largest trailer park.” That development is one third the size of this one!

Nine years ago, Colony Ridge didn’t exist.

Satellite image from 2011. The land that would become Colony Ridge was covered with forests, wetlands and rice fields. Paper companies owned most of this land for decades and periodically harvested timber.
Colony Ridge today. This is just the southern section. Two more sections are out of frame on the north.

By the end of 2019, Colony Ridge had grown to cover approximately 10,000 acres and it’s still expanding. It has transformed the landscape massively, and it’s not clear whether the development has provided sufficient detention to keep runoff at its predevelopment rate. Judging by the frequency of flood damage to surrounding homes and roads since Colony Ridge was developed, many local residents believe the answer is no.

Documentation about the design and effectiveness of the drainage systems is hard to come by. Authorities in Liberty County have not returned emails or phone calls. And the information is not posted online.

Entire Population Growth of Liberty County in Last Decade

Colony Ridge alone can account for all of the population growth in Liberty County in the last decade. The U.S. Census Bureau officially estimates that Liberty County’s population grew from 75,000 to 88,000 between 2010 and 2019. Unofficially, one local politician estimates the population of Colony Ridge to be about 20,000. Firm numbers are difficult to come by because many residents are undocumented and uncounted.

Contributing to Flooding?

Thousands of acres of trailer homes with open-ditch drainage and no deed restrictions.
Typical landscape in Colony Ridge is highly susceptible to erosion and rapid runoff.

The lack of deed restrictions means many have not planted grass. That accelerates runoff.

Also consider that the developer created many of the lots by filling in wetlands and clearing trees that used to retain water in storms. The absence of wetlands and trees also accelerates runoff.

Wetlands drained by Colony Ridge from USGS National Wetlands Inventory.

Contributing to Road Blow Out

FM1010 lies in the path of a drainage ditch more than 2.5 miles long and 60 yards wide in places. It cuts like a butcher knife through the heart of Colony Ridge.

Satellite image shows massive erosion in straight-line drainage ditch that stretches for 2.5 miles toward Plum Grove Road, out of frame on the left.

The straight line nature of such ditches accelerates water and erosion even more. During Harvey, a combination of factors (population growth, lack of ground cover and deed restrictions, design of drainage, loss of forests and wetlands, impervious cover and extreme rainfall) all contributed to washing out FM1010. (See images below.)

Acceleration of runoff also shortens the time of accumulation during floods which heightens flood peaks.

Effect of Urbanization on Peak Stream Flows” by Dr. William Dupre, professor emeritus from the University of Houston.

One Person’s Dream Turns into Another’s Nightmare

The developer of Colony Ridge had an attractive vision for a niche market: to provide affordable plots of land without deed restrictions (at least in the early stages) to low-income families trying to escape the City. He marketed mainly to Hispanics who dreamed of owning their own land in America. The result may be a dream for some, but it’s turning into a nightmare for others.

A low-altitude shot looking west toward Plum Grove Road (concealed in tree line in distance).

Unintended Consequences or Foreseeable Tragedy

The giant ditch shown above leads directly to where FM1010 washed out. Along the way, there’s little to slow water down. The developer has installed twin culverts under a road that crosses the ditch. They may help. But judging by the results, they’re not working very well.

Cropped and enlarged from wide image above of Colony ditch.

From the bridge above, the elevation drops more than 27 feet in three quarters of a mile before stormwater goes into a strip of woods between FM1010 and the development. There, it gathered the momentum to blow out the road.

In the last part of its journey across Colony Ridge to the East Fork (left), water drops 27 feet with only a strip of woods to slow it down before it reaches the part of Plum Grove Road that washed out.
FM1010, Plum Grove Road has been impassible since Hurricane Harvey 1020 days ago.
Looking upstream toward Colony Ridge out of frame in the background (upper left)
Looking downstream toward the East Fork about 200 yards to the east.

Detours and Delays

More than 2.5 years after Harvey, this road has yet to be repaired.

The loss of FM1010 makes northbound traffic detour through Colony Ridge or up US59 and then back east. As a result, residents say that it can now take an hour during rush hour to go the five miles from US59 to Plum Grove on FM 2090. But that’s not the only problem.

Rapid Sedimentation Downstream

Downstream from Colony Ridge, we’re now getting rapid sand build ups on the East Fork, much like we have on the West Fork from sand mines. According to boaters, the area shown below was 18 feet deep before Imelda. The deepest point in the channel when this picture was taken last December was 3 feet.

Growing East Fork Mouth Bar

A massive development, such as Colony Ridge, without appropriate safeguards against erosion, contributes to this buildup. They certainly aren’t the only contributors. Sand mines that provided the aggregate for the roads in Colony Ridge have certainly helped.

Posted by Bob Rehak on 6/14/2020

1020 Days since Hurricane Harvey and 269 since Imelda

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.