Tag Archive for: Brooklyn trails

Guefen Clears 17 Acres Between KPHS, St. Martha for 131 High-Density Homes. Will Detention Pond Be Enough?

Guefen Development Partners has announced that it will build a “luxury single family build to rent multifamily community” [sic] on 17 acres between Kingwood Park High School and the St. Martha Church on Woodridge Parkway.

Future site of Preserve At Woodridge. Looking W toward St. Martha Church across a drainage ditch that empties into Bens Branch.

Nine Homes Per Acre with 65% Impervious Cover

Guefen will build 131 units on 14.65 acres. The rest of the 17 acres will contain a detention pond. That works out to nine homes per acre. RG Miller, the firm that engineered the “Preserve at Woodridge” estimates the development will have 65% impervious cover. See the Plans here. (Caution: large file, 21 mb download.)

Grass will definitely be in the minority. I’m not sure what the Preserve is preserving. The site certainly preserves no trees.

Pictures Taken This Week

Here’s what Guefen’s land looks like as of this week.

Looking E. Cleared area between St. Martha and Kingwood Park High School baseball fields will hold 131 homes and a detention pond.
Guefen’s detention pond will border the drainage ditch that empties into Bens Branch about a block south.

Basis of Detention-Basin Calculations

The technically inclined reader may appreciate the detention calculations below. The basis for the calculations is a 16.1 inch rain in 24-hours which is the Atlas-14 amount used throughout Montgomery County. MoCo specifies an average to keep things simple for developers. Their average is slightly less than the 17.3 inches specified by NOAA for the Kingwood area.

See pages 17-24 for the drainage portion of the subdivision plans.

Will the Detention Pond Be Enough?

With other high-density developments going in upstream along Bens Branch, I hope Guefen’s detention pond capacity will suffice. Brooklyn Trails, several blocks upstream on another tributary of Bens Branch, lacks about 30% of the capacity needed to meet Atlas-14 requirements according to my calculations.

Montgomery County’s Subdivision Rules and Regulations specify that outfall ditches, such as the one in the first photo above only need to carry a 25 year rain. (See page 9.) With that in mind, it seems like Guefen’s detention pond so near a ditch would fill up quickly from ditch overflow in a 25-year rain and provide little detention benefit for anything heavier, for instance, 50-100 year rains.

If that ditch ever needs to be widened, like Hall’s Bayou, the fact that so many homes are built so close to it will severely limit mitigation options.

You can’t build mitigation projects if you don’t have the land.

668 SF Homes with “Interior Garages” and “Luxury Vinyl” Flooring

The 131 single-family detached homes will range in size from 668 square feet to 1,255 square feet and feature “luxury vinyl” flooring. The press release boasts of an “amenity suite” including interior garages. It’s hard to imagine how much living space would be left in 668-SF homes with “interior garages.”

So I checked the plans. I found 29 parking spots labeled “garage spcs.” Many more exterior parking spaces exist. But no one, it appears, will be unloading groceries from his/her car directly into a kitchen. Your “interior garage” could be several homes away.

Nor do all the homes front on a street. That’s going to make moving day hard for your college buddies. You know who your real friends are when they’ll go the distance for you.

Speaking of going the distance, in case of an emergency, that firetruck may be parking 250 feet away from some homes. That’s almost the length of a football field.


According to Guefen’s website and press release, the company sees a niche market for this type of housing in the Kingwood area. They are building these homes to rent them, not sell them. The company normally specializes in multifamily and student housing.

While plans show detached homes, they also show five to six feet of separation. That should be enough to dampen most stereos. So party on, Wayne!

Posted by Bob Rehak on 11/10/2021

1534 Days since Hurricane Harvey

HCFCD Recommends Expanding Diversion Ditch as First Priority in Kingwood

At the Harris County Flood Control District’s (HCFCD) Kingwood Area Drainage Analysis meeting tonight, HCFCD recommended that expansion of the Kingwood Diversion Ditch should be the community’s highest priority.

The Diversion Ditch project would help address several potential problems. Expanding it would remove 62 structures from inundation areas and another 586 structures would benefit from improved local drainage. In addition, the project:

  • Can divert floodwater from Ben’s Branch, which will be a much more complicated project, taking more time.
  • Has a 300-foot right-of-way, of which only half is being used
  • Has bridges that already span the entire 300 feet.
  • Will help carry floodwaters from rapidly growing south Montgomery County.

History of Diversion Ditch

In the early days of Kingwood, Friendswood Development Company built the Diversion Ditch to reduce water flowing into Ben’s Branch. But since then, upstream development and larger rains have stressed the capacity of both Ben’s Branch AND the Diversion Ditch. Engineers estimate that peak flows have doubled since 1985.

Most of Ben’s Branch is Natural Channel

Ben’s Branch cuts diagonally through the heart of Kingwood. See red lines below. More than half its length – between Woodland Hills and Rocky Woods Drive is natural channel. Widening it will be complicated and take much time.

Red Line indicates approximate path of Ben’s Branch through Kingwood.

Ben’s Branch Now at 2-Year Level of Service

However, areas on both sides of Ben’s Branch are threatened by flooding as you can see in the image below from FEMA’s Flood Hazard Viewer.

Ben’s Branch once had a 100-year level of service, meaning it had enough carrying capacity to prevent homes from flooding in everything but a 100-year rain. Models based on new Atlas-14 rainfall probability frequencies indicate that the channel’s capacity is now down to a 2-year level of service. That means it will flood in minor rains, exactly as St. Martha School did last year.

Worse yet, Ben’s Branch has decreased to a 2-year level of service throughout its length.

HCFCD Kingwood Area Drainage Analysis
Source: Fema’s Flood Hazard Layer Viewer. Cross-hatched equals floodway, aqua = 100 year floodplain, brown = 500-year floodplain. Floodplains shown above are based on pre-Atlas-14 rainfall probability statistics. An Atlas-14 hundred-year rain is about 30-40% higher than the old hundred-year rain.

When flood maps are updated based on Atlas-14 statistics, those floodplains will likely expand…unless we do something to handle more floodwater before then.

However, Ben’s Branch will not move to preliminary engineering right away.

How to Protect Against Bigger Rains and More Upstream Development

The Kingwood Area Drainage Analysis sought to understand what we need to do to restore a 100-year level of service to all ditches and streams based on Atlas 14. Of the 19 ditches and streams studied, nine need improvement. The level of service for some, including Ben’s Branch, has been reduced to 2 years.

Expanding the Diversion Ditch is the fastest way to take pressure off of Ben’s Branch.

The Diversion Ditch intersects Ben’s Branch at the new St. Martha Church. It then flows south to Deer Ridge Park and then winds through River Grove Park. See the white line below.

Kingwood Diversion ditch (white line) intersects Ben’s Branch near the new St. Martha Church.

Expansion Capacity Already Built into Diversion Ditch

Engineers foresaw the day when Kingwood would need more drainage capacity due to upstream development in Montgomery County. They built the Kingwood Diversion Ditch to handle the extra stormwater. They also made the bridges over the diversion ditch wider than they needed at the time. Finally, they dedicated a flood easement on both sides of the ditch that was wider than they needed, so they could expand the ditch later without encroaching on neighboring properties. Here’s how it looks from the air.

Looking north across Northpark Drive toward Bens Branch, which cuts diagonally from left to right through the middle of the frame. Note the ample clearance under the bridge and the wide shoulders of the ditch. St. Martha Church is in the upper left.
Looking south toward Kingwood Drive at the Diversion Ditch. King’s Mill is on right in foreground.

Both Kings Mill and Kings Manor now drain into the Diversion Ditch. But they came long AFTER Diversion Ditch construction. Other new upstream developments that drain into the Diversion Ditch and Ben’s Branch include Brooklyn Trails and Woodridge Forest, both in Montgomery County.

As a result, the Diversion Ditch itself has decreased to a 2- to a 25-year level of service in places. However, it still offers a 100-year level of service in others.

Looking NE toward Deer Ridge Park from over Hamblen Road. A corner of Deer Ridge Estates is on the left. The diversion ditch cuts in front of the park (upper left to lower right) and goes into an area largely undeveloped on its way to the river (out of frame to the right).

Impact on River Grove Park

Once the Diversion Ditch passes through the area shown in the photo above, it enters wetlands and winds through River Grove Park. Two questions arise. How do we protect, from additional flow:

  • The park?
  • People downstream on the West Fork?

The first question is simple: split the flow in two. Take part through the undeveloped area west of the park. See the green below.

Green Line represents one possible route for diversion of the diversion ditch.

The second question is more complicated. We need a retention basin to hold the extra stormwater until the peak of any flood passes on the West Fork. But where? The closer you get to the river, the lower the elevation. Because of that, the basin could fill with floodwater from the river before it fills with floodwater from upstream. Fortunately, some large tracts of land exist on higher ground that could be purchased. HCFCD estimates the need at 1248 acre-feet. Preliminary engineering should start soon to address these issues.

Upstream Development Not Addressed by Analysis

Unfortunately the Kingwood Area Drainage Analysis did not address upstream development issues in Montgomery County. That was beyond the scope of work. Regardless, such issues must be addressed somehow, someday soon. Otherwise, even the improvements we invest in today could soon be overwhelmed by additional floodwaters.

In that sense, these channel improvements represent a stopgap measure. The real solution lies in making everyone in the region realize that we are all in this together.

Additional Resources

If you missed the presentation, you can view it on YouTube.

Here is a PDF that contains the District’s summary of the Kingwood Study. It includes a spreadsheet comparing the improvements plus data sheets on the nine recommended projects.

The ten remaining channels/streams already offer a 100-year level of service. Therefore, no improvements are needed. HCFCD felt Taylor Gully should be the next priority after the Diversion Ditch. But the possible purchase of Woodridge Village may require re-thinking project requirements. Specifically, if Woodridge turns into a giant detention basin, the channel may not need as much deepening or widening.

Posted by Bob Rehak on 10/20/2020

1148 Days since Hurricane Harvey

Dwindling Lot Sizes and Their Impact on Flooding

During the last month, more than a dozen people have written me expressing concerns about nearby developments with high-density housing. They felt it might contribute to flooding their properties. They may be right. But the story is not simple. Many people see benefits, too. Whether you are for or against such developments will depend on circumstances and your point of view.

During the last three decades, the homebuilding industry has seen a trend toward dwindling lot sizes. As lots have shrunk, the percentage of lots occupied by homes has grown. We are now at the point where developers will need a shoehorn to squeeze homes onto lots. Nationally, Texas has the smallest lots with the exception of the Pacific Coast. As one looks at these new smaller lots from the air, it’s hard to see where one could squeeze in a tree. Growth of impervious cover, one factor that contributes to flooding, staggers the imagination. What’s driving this trend? And is flooding an inevitable consequence

Driving the Trend: Affordability

According to the Department of Housing and Urban Development, a combination of housing underproduction and higher consumer demand, particularly among millennial first-time homebuyers who delayed household formation as a result of the 2008 recession, is contributing to rising housing costs. 

Significantly, the cost of entry-level homes has risen much more sharply than overall home prices or the prices of luxury homes. Even when first-time buyers can purchase a new home, they increasingly buy farther from city centers. This trend can impact the amount of time people spend commuting and influence regional infrastructure needs.

Further, the number of cost-burdened owners (those paying more than 30% of their income on housing) has receded to pre-2008 levels, whereas the number of cost-burdened renters remains close to peak levels.

Housing affordability has become a real issue.

Buyers More Willing to Sacrifice Lot Size than Home Size

Builder Magazine cited a study by Freddie Mac and the National Association of Homebuilders (NAHB). It found that reducing home buyers’ spending on land, rather than housing, is one method to improve housing affordability.

Research published in 2017 by the Federal Reserve shows the median size of a single-family home built from 1980 to 2014 grew by 50 percent, but the median lot size decreased by more than 20 percent during the same period.

In other words, builders are squeezing bigger homes onto smaller lots.

Builder Magazine

A graph from a Federal Reserve Board study dramatically illustrates these trends.

Lot Sizes Hit Record Low in 2019

According to the NAHB and US Census Bureau, median single-family lot sizes have hit a record low.

Regional Variation in Lot Sizes

The same article points out that some of the smallest lots can be found in Texas, a state with almost unlimited amounts of land.

Land Costs now 39% of Building Costs

Land costs largely drive these trends. NAHB says that, on average, 55.6 percent of the final sales price of a new home goes to construction costs and 21.5 percent to finished lot costs. While that’s less than a quarter of the total home cost, it’s 39% of construction costs. The NAHB shows that land costs are the single largest cost component of a new home (largely because construction costs are broken down into smaller categories, such as contractors, materials, etc.).

As a consequence, developers are packing homes into lots tighter than sardines. See the photos below.

Two Porter Examples

Northpark Woods off Sorters-McClellan Road lies in a flood plain. Homes and driveways take up more than half the lots. Also, the detention pond, not shown in this photo, is very close to the floodway of the San Jacinto West Fork, limiting its usefulness in a flood. Both problems raise concerns.
These homes in Porter’s Brooklyn Trails development are sandwiched between railroad tracks and a sewage treatment plant.

The average lot size in Porter’s Brooklyn Trails Development is .12 acres (about an eighth of an acre). The homes range from 1,307 to 2,628 SF. The builder aggressively markets them to first-time buyers stepping up from apartments by promoting “closing cost assistance,” “free washer, dryer, fridge,” and prices starting from $170,000.

Entry sign
Entry sign targeting renters who are more “cost burdened.”

Compensating for a Higher Percentage of Impervious Cover

According to Matt Zeve, deputy executive director of the Harris County Flood Control District, hydraulic models used to calculate detention pond requirements in such developments typically factor in the percentage of impervious cover. So do most flood plain regulations.

However, in the case of Brooklyn Trails, I discovered via a Freedom of Information Act Request to Montgomery County that the developer filed its application for a building permit two weeks before new Atlas-14 rainfall frequency estimates went into effect. This was another case of “beat the clock.”

As a consequence, Brooklyn Trails will only have 60% of the detention pond capacity needed for this area. They got to define the 100 year/24 hour rainfall as 10″ instead of 17.3″. A smaller detention pond means more buildable lots.

Buyers will only pay the upfront costs. Neighbors and downstream residents will pay the backend costs – in flooding. This is bad. But the badness stems more from inadequate detention than lot size.

Three Recent Developments in Spring, TX

New development in Spring, TX
Development in Spring, TX
Spring TX

Many Governments Use Regulation to Reduce Impervious Cover

Google “flooding” and “lot size.” You will find thousands of articles and regulations from across the US. Most see regulation of minimum lot size as a tool to reduce impervious cover and therefore flooding. Rhode Island, for instance, says “Under natural forested conditions, only about 10% of precipitation runs off the surface of the site, 50% soaks into the ground, and a surprising 40% is taken up by trees and other vegetation and sent back into the atmosphere through the process of evapotranspiration.” Total runoff volume for a one-acre parking lot, they say, is about 16 times that produced by an undeveloped one-acre meadow.

New York also recommends larger minimum lot sizes to reduce the number of building lots that may be created, providing greater area for natural systems to process stormwater and reduce flood risk. They also advocate “maximum lot coverage standards.” That helps explain why land-starved New England has the largest minimum lot sizes in the country – .6 acres (see US map above).

But the story is a little more complicated than just reducing the amount of impervious cover. With sufficient, mandatory detention and enforcement of regulations, theoretically, developers could offset the volume of water soaked up by all those trees and grasses.

High-Density Developments Have Benefits, Too

In addition to lower home costs, high-density developments offer several other benefits. You may or may not value or agree with.

Higher density uses infrastructure more efficiently. For instance:

  • One fire station could cover two or three times as many homes without compromising response time.
  • You can also pack more homes on a street; that uses less concrete for streets.
  • Smaller lots mean more homes on available land, which generally increases tax revenues for cities and counties.
  • They also limit urban sprawl, which can preserve floodplains beyond the reach of the City.
  • Less sprawl also means less commuting, which reduces energy consumption and gives people more time to spend with families.
  • Higher density creates tighter neighborhoods, where people interact more with each other.
  • And finally, higher density encourages more walking, which leads to healthier lifestyles.

We need more research to quantify these tradeoffs. In the meantime, “dwindling lot size” doesn’t automatically go into the win or loss column. Smaller lots have value, just as they have drawbacks. The real issue has to do with building enough detention to offset the high rates of runoff. And whether you still have a Millennial living in your spare bedroom.

Posted by Bob Rehak on October 11, 2020

1139 Days since Hurricane Harvey

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.

Big Stories to Watch in 2020

As we enter 2020, keep your eyes on these stories.

Elm Grove Lawsuits and Mitigation

In 2019, Elm Grove flooded twice with runoff from the Perry Homes/Woodridge Village development in Montgomery County. Hundreds of homeowners sued Perry Homes’ subsidiaries (PSWA and Figure Four Partners) and their contractors.

On 12/17/19, attorney’s for the plaintiffs filed a fourth amended petition. Since the original filing, plaintiffs have named Double Oak Construction and Texasite LLC as additional defendants.

The judge set a jury trial date for July 13, 2020. To date, Perry Homes has done nothing to reduce the threat of flooding from their job site.

The 268-acres clear-cut acres that contributed to Elm Grove Flooding.

That brings us to the subject of mitigation.

What can be done to restore the safety of residents?

Perry Homes has demonstrated no interest in reducing the threat to downstream flood victims.

Protecting homeowners will require massive intervention from an outside source. But who? And how?

Harris County Bond Fund Mitigation Projects

In 2019, Harris County Flood Control began work on 146 of 239 of the projects identified in their $2.5 billion flood bond.

Many of those projects required studies and partners. Three affecting the Lake Houston Area are:

Many projects could actually enter the construction phase next year.

Recommendations from each study should come out in 2020. Then many more projects will get underway.

Upstream Development

In 2019, we saw what upstream development did to homes in Elm Grove and North Kingwood Forest bordering Taylor Gully.

I recently learned of two new developments in the Ben’s Branch watershed.

  • A developer intends to build 18 acres of apartments where the woods adjacent to the new St. Martha Church now stand.
  • Another developer intends to build hundreds of homes on tiny lots on an 80-acre site just north of St. Martha’s.

These two projects represent dozens of others gobbling up farm and forest land in southeast Montgomery County.

This drainage ditch feeds into Ben’s Branch at Northpark Drive. The 18 acres of trees on the other side of the ditch could soon become apartments.

Businesses such as the St. Martha School and Kids in Action already flooded twice this year. So did dozens of homes along Ben’s Branch.

Additional upstream development has the potential to make flooding even worse. This is like death by a thousand cuts. Residents just don’t have the time or energy to monitor each development to ensure that owners follow rules and regulations for wetlands, floodplains, drainage, etc. Neither evidently does Montgomery County. Which brings us to…

Montgomery County Standards and Enforcement

Montgomery County competes for development by touting its lack of regulations. That’s a huge problem for downstream residents.

  • Montgomery County still bases flood maps on data from the 1980s.
  • Large parts of the county remain unmapped for flood hazards.
  • The County last updated its Drainage Criteria Manual in 1989.
  • Developers ignore many provisions within it.
  • County Commissioners voted to leave loopholes open that allow developers to avoid building detention ponds.
  • The County even paid an engineering company to investigate itself for its role in the Elm Grove Disaster.

You get the idea. If you thought some benign government entity watched over new developments to protect downstream residents, think again. Below you can see the 80-acre site I mentioned above.

Source: USGS National Wetlands Inventory.

Note how it was covered in wetlands. Developers did not ask permission from the Corps to remove them. They just decided on their own that they didn’t need to ask.

Below, you can see how virtually half the site is in a flood zone or floodway.

Source: FEMA’s national flood hazard layer viewer. Brown = 500 year flood plain, aqua = 100 year, cross-hatched equals floodway.

Here’s how it looks in Google Earth. Developers have already cleared the site.

Developers intend to build high-density homes in the floodplains. They will also build their detention pond in the floodway. Those hazard areas will likely expand when and if the County incorporates new Atlas-14 data into their flood maps.

Layout for Brooklyn Trails development in Montgomery County

None of this seems to bother the leadership of Montgomery County. And that’s a bigger problem than any one development.

In 2020, expect more focus on the decision-making process and decision makers who have created a permissive culture of indifference to flooding problems.

Sand Mines

Sand mines operate so closely to the San Jacinto that their walls frequently break and pour polluted process water into the drinking water for 2 million people. If they get caught, they pay a small fine and continue operating with impunity.

Left: Liberty Materials Mine in Conroe that undercut five pipelines carrying highly volatile liquids. Center: Triple PG mine in Porter where erosion during Imelda exposed one natural gas line and threatens 5 more HVL pipelines. Right: Another Liberty Materials mine that allegedly dumped 56 million gallons of white goop into the West Fork.

Upstream Detention

During Harvey, the release of 80,000 cubic feet per second from Lake Conroe added to downstream flooding. The goal: to find enough upstream detention capacity to help offset future releases. The San Jacinto River Basin Study will examine that possibility. It’s unlikely that one reservoir will provide enough capacity. However, multiple smaller reservoirs may.

Peak flow map during Harvey.

The study partners will release their results in the second half of 2020. Land acquisition and construction could take several additional years.


Dredging is another essential element of flood mitigation on the West Fork of the San Jacinto. Sand buildup near the mouth of the river has created a giant sediment dam. The Army Corps removed three feet in a dredging effort that ended on Labor Day. But much remains.

Luckily, State Representative Dan Huberty sponsored legislation that allocated another $30 million. The Harris County Flood Bond allocated $10 million. The City of Houston allocated $6 million. Plus two more grant requests are still pending that could increase the total even more. And a disposal site for the material has already been permitted.

Mouth Bar of the West Fork. Photo taken 12/3/2019.

Last week, Harris County commissioners voted to proceed with additional dredging. Project managers are studying the most cost effective ways to proceed. We should see more dredging soon.

This money could also be used on the growing mouth bar of the East Fork.

State Highway 99 Extension

The extension of the Grand Parkway (State Highway 99) east and south to I-10 will open up vast new expanses of forest and farmland to high density development. The biggest threat will be to the East Fork watershed as construction moves through southeast Montgomery County and the northeast tip of Harris County into Liberty County.

Eastward clearing for SH99 has reached Caney Creek near Lake Houston Park.

Those are my predictions for the biggest stories of 2020. There’s a lot of good news in the forecast and much to remain vigilant about. Life seems to be a constant struggle between those who would increase and decrease our margin of safety when it comes to flooding.

Posted on 12/21/2019 by Bob Rehak

844 Days after Hurricane Harvey

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.