At the current rate of work, Perry Homes could easily take 3-4 years to complete the detention ponds on its Woodridge Village development. The chances of getting another rain event like May 7th during that period? 27.1% if it takes Perry 3 years and 34.4% if it takes 4.
Perry has moved only a few shovels full of dirt since early August to expand detention capacity. That’s when construction activity came to a virtual standstill.
Despite an October 17th letter from Perry Homes’ lawyer to the City Attorney promising to accelerate work on detention ponds, the company has not.
This significantly raises Perry Homes’ legal liability if Elm Grove floods again.
How to Determine Cumulative Probabilities
How do you compile those statistics? Start by classifying the storm. The May 7th storm that flooded approximately 200 homes was a 10-year event, according to USGS, NOAA and National Weather Service statistics below.
Next, figure the cumulative probability of it happening again during a given time period. If you ask, “What are the chances of another May 7th happening in any year,” the answer is always 10%. But if you ask, “What are the chances of another May 7th happening in the next three-years,” the answer is different.
You calculate the cumulative probability using the following formula:
Probability of at least one 10-year storm in next 3 years = 1 – (9/10)3rd = 27.1%. Four years equals 34.4%.
The possibility exists that the rainfall rate may have been slightly higher in Elm Grove on May 7th. But these are official statistics and conservative for the purposes of estimating risk. They don’t even include the chances of getting hit by even larger storms in the same year (as we did with Imelda).
Legal Risk of Not Mitigating Flood Risk
Perry Homes has shown little desire to mitigate flood risk by expanding detention capacity at Woodridge – even after promising the City of Houston it would do so.
After clearcutting virtually the entire site, Perry had installed only 7% of the required detention ponds when the May 7th flood hit and only 23% by the time Imelda hit on September 19. Since then? Virtually nothing!
What Perry Homes Has and Hasn’t Done
Since the October 17th letter laying out a 26-month timetable for completing work on Woodridge detention ponds, Perry Homes HAS:
- Removed several brush piles from their northern property (shown above)
- Slightly widened 300 feet of Taylor Gully
- Concreted a portion of the 300 feet (see below).
- Moved a small amount of dirt from the S2 pond that eroded into it back up onto the banks (see below).
- Spread some grass seed on the northern portion of the development (see two photos below)
Perry Homes has NOT:
- Finished work on the S2 detention pond.
- Started work on other detention ponds.
- Managed to keep ponding water from reducing the volume of S2.
- Established grass on pond banks to reduce erosion as regulations require.
- Finished the spillway into S2 from Taylor Gully.
- Fenced in their detention ponds as regulations require.
- Installed maintenance roads around the ponds as regulations require.
- Released its internal investigation into the causes of Elm Grove flooding as it promised Channel 2 news.
Perry Homes Increases Risk to Residents and Itself
Since August when Perry Homes virtually stopped working on Woodridge, the company has done nothing to allay the major causes of flooding: clearcutting and lack of detention. It has slow-walked this project. Whatever its motivation, Perry Homes has significantly increased the risk of flooding Elm Grove residents again. In doing so, it also increases its own risks.
If Perry Homes does flood Elm Grove again, its slowdown and disregard for the promises it made to the City in its October 17th letter could prove the difference between negligence, gross negligence and punitive damages.
According to the Sawaya Law Firm, “Gross negligence is the extreme indifference to or reckless disregard for the safety of others. Gross negligence is more than simple carelessness or failure to act. It is willful behavior done with extreme disregard for the health and safety of others. It is conduct likely to cause foreseeable harm.”
Kathy Perry Britton knows that slow-walking the expansion of detention capacity will increase the risk of another major storm hitting Elm Grove before she finishes. But I doubt her lawyers are telling her that risk could be as high as 34%.
Posted by Bob Rehak on 12/15/2019 with help from Jeff Miller
838 Days since Hurricane Harvey and 87 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.