Plaintiffs’ Engineer Alleges LJA Issued Misleading Studies, Followed Wrong Guidelines in Elm Grove Flooding Case
Fourteen documents filed with the Harris County District Clerk’s office on February 27, 2020, lay out the case of plaintiffs in the Elm Grove flooding case against LJA Engineering, Inc. Lawyers for the plaintiffs named LJA as an additional defendant in their most recent amended petition. Other defendants include Perry Homes’ subsidiaries and contractors: Figure Four Partners, LTD.; PSWA, Inc.; Rebel Contractors, Inc. (which recently changed its name); Double Oak Construction Inc.; and Texasite LLC.
Accusations Specific to LJA
The amended petition alleges LJA:
- a. Failed to follow the correct drainage guidelines in Montgomery County;
- b. Failed to provide adequate drainage in the Development;
- c. Failed to adequately model the Development;
- d. Failed to adequately report the modeling;
- e. Removed drainage channels;
- f. Caused post-development discharges and water surface elevation to increase downstream of the Development;
- g. Failed to design detention ponds with adequate capabilities for rain events;
- h. Failed to use the correct hydrology method;
- i. Failed to design emergency overflows for the detention ponds;
- j. Failed to notify the Developer Defendants and Contractor Defendants of the importance of the existing levee; and,
- k. May be liable in other ways described in the consulting engineer’s report.
Consulting Engineer Says LJA Used Outdated Drainage Criteria Manual
The defendants’ consulting engineer, L. David Givler, MSCE, PE, provides the details that back up these claims. Givler is president of Givler Engineering, Inc. Givler’s firm is licensed in Texas to design drainage projects similar to Woodridge Village, which was designed by LJA. A “Certificate of Merit” filed with the court states Givler’s credentials and conclusions. Givler also provides thirteen more exhibits as part of his affidavit. (See links at bottom of post.)
Perhaps Givler’s most explosive finding: LJA based all of its conclusions on an outdated version of the Montgomery County Drainage Criteria Manual (DCM) developed in 1989. MoCo has since updated its DCM twice – in December 2014 and July 2019. Givler asserts that LJA should have used the 2014 version when it submitted its drainage analysis in 2018. The rainfall that MoCo requires engineering firms to design detention basins for have increased since 1989 (see below).
Givler asserts that the increases, along with other other errors and omissions outlined below critically skew modeling results. Ponds that might not overflow based on the 1989 rainfall depths do overflow with 2014 and 2019 rainfall statistics.
Critical Levee Removed, But LJA Did Not Model Effect of That
Givler says in his testimony that grading associated with the construction project removed a levee that had been constructed along the south side of Taylor Gully. “Prior to being removed, the levee had successfully protected the Elm Grove Village Subdivision from flooding,” said Givler. “However, removal of the levee increased the probability for Taylor Gully to overflow southward and to flood the Elm Grove Village Subdivision.”
Givler asserts that the levee successfully protected Elm Grove from flooding in previous extreme events such as Hurricane Harvey, which he characterized as a 330-year storm.
LJA Did Not Use MoCo’s Recommended Method For Modeling Runoff
Mr. Givler also found that LJA did not use Montgomery County’s recommended method for modeling runoff. LJA used something called the Clark’s Unit Hydrograph Method instead of the NRCS Hydrograph Method specified in the 2014 version of the County’s Drainage Criteria Manual. The latter shows significantly higher peak runoff rates, according to Givler. “LJA’s selection of an alternative method (The Clark Method) caused the underestimation of peak runoff rates,” said Givler. “LJA also used low, outdated rainfall depths in its model, which exacerbated the underestimating of the peak runoff rates.”
Givler modeled whether LJA’s designs for the Woodridge Detention Ponds would have successfully held the runoff from the updated drainage criteria manual.
He found that the design for the ponds was “inadequate.” They overflowed. Significantly, Givler also found that LJA underestimated the volume of runoff sent downstream to Taylor Gully.
After May, Protection Not Implemented Against September Storm
“Even after the May 2019 flood, adequate measures had not been implemented to restore the pre-development level of protection or to prevent a recurrence,” said Givler. “Under Woodrige Village pre-development conditions, the Elm Grove Village subdivision was safe from flooding during the 330-year Hurricane Harvey rainfall. However, under construction conditions at Woodrige Village, Elm Grove Village was vulnerable to flooding in the 19-year and 92-year rainfall events.”
LJA Did Not Model Effect of Overflow Channel
Givler also noted that LJA’s plan claimed that the 100-year peak stage for the S2 detention pond would be 73.21. That would be high enough to cause water to backup into the grass-lined channel (bottom elevation 68.50) located at the northeast corner of the pond. “Since the highest adjoining ground elevation south and east of the grass-lined channel is approximately 72,” said Givler, “the peak 100-year stage would discharge to Taylor Gully downstream of the project and to the neighborhood east of pond S-2 [North Kingwood Forest]. Such discharges would increase flooding to the residential lots to the east…”
Emergency Overflow System Not Provided
Another problem that Givler found: Section 7.3.13 of the Montgomery County Drainage Criteria Manual (2014 version) requires an emergency overflow system shall be provided “…designed to carry the 100-year allowable detention basin discharge at full-bank conditions… The emergency overflow system shall direct flows into an outfall channel and prevent flow in the direction of developed areas.” (as quoted by Givler).
Even today, the project does not include such an overflow system.
Runoff During Construction More Severe than Ultimate Buildout Conditions
Givler modeled actual construction conditions after the May storm. He found that “…with the project site cleared and stripped of vegetation, runoff conditions were more severe than even the ultimate buildout condition. LJA’s analysis does not address this condition,” he says. His analysis showed that under construction conditions, LJA’s partially-constructed detention ponds were inadequate, unable to contain the May 2019 runoff and the 100-year runoff.”
The temporary construction conditions he says, “caused the ponds to overflow and to discharge runoff to the Elm Grove Village subdivision at a peak rate of approximately 2,110 cubic feet per second.”
“LJA Failed to Act as a Reasonably Prudent Engineering Firm”
In his conclusions, Givler alleges that “LJA failed to act as a reasonably prudent engineering firm.” He added, “…three professional engineers and the engineering firm were negligent in the provision of professional services that they rendered, and they committed various actions, errors, or omissions in providing professional services by violating standards required by Montgomery County.”
In Givler’s opinion, LJA failed to comply with Montgomery County standards by:
- a. Using an alternate (Clark) hydrology method rather than the NRCS method recommended by Montgomery County, resulting in the underestimation of the amount of runoff that the watershed would discharge to the detention ponds.
- b. Using rainfall depths in the hydrology models which are smaller than what was required by the applicable county standard (2014 DCM) and that are much smaller than recently adopted values (2019 DCM).
- c. Designing detention ponds, which are too small to contain and too small to detain or attenuate the 100-year design flood.
- d. Failing to design adequate freeboard for the detention ponds.
- e. Failing to design adequate emergency overflows for the detention ponds.
- f. Designing a project, which diverts runoff to properties of others in a harmful and detrimental manner.
- g. Allowing peak runoff discharges downstream of the project to increase due to the impact of the project and due to the limited effectiveness of the detention ponds.
- h. Allowing water surface elevations downstream of the project to increase due to the impact of the project and due to the limited effectiveness of the detention ponds.
- i. Erroneously representing that the project had no impact on downstream areas.
- j. Failing to notify the contractor of the importance of the existing levee.
- k. Failing to guide the contractor in a logical construction sequence that would reduce the flood risk during construction.
Violation of Professional Standards and Ethics Also Alleged
Mr. Givler also alleges that LJA and three of its employees violated standards established by the State of Texas and the Texas Board of Professional Engineers in the Texas Engineering Practice Act. “This negligence caused and/or contributed to the endangerment of lives, health, safety, property and welfare of hundreds of people near the project,” he says. They did this, he asserts, “by issuing misleading reports, which failed to indicate the increase in flood potential.”
“I recognize that additional documents may be produced,” said Givler, “which I will be asked to review and, therefore, reserve the right to add to or to modify this affidavit based on information that may be provided to me at a later time.”
Except for general denials, neither LJA, nor any of the other defendants in this case have responded publicly yet to Givler’s specific allegations.
When LJA and the other defendants make their positions public, I shall review them and give them “equal time.”
The big questions I have at this time are:
- Why would a firm with LJA’s substantial reputation make the blunders that Givler asserts? Were they pressured into producing a favorable report that made the economics of the project “work”?
- Five previous developers owned this land and, after studying it, decided not to develop it. That certainly should have raised red flags for LJA and Perry, and caused them to review this closely. There must have been scuttlebutt circulating among local professionals. One engineer I consulted said Friendswood walked away from this property decades ago because it would have been too hard to develop. However, Perry decided to move forward based on dubious studies and incomplete data. Why?
- What did Concourse Development, Woodbridge 268, Reddy Partnership, Kingwood 575, Lennar Homes of Texas/Friendswood know that Perry Homes did not?
Check out the original text of Mr. Givler’s affidavit and exhibits for yourself to ensure I summarized them fairly. His affidavit includes his findings, professional opinions, conclusions and Exhibit 1, his resume.
Exhibit 2 includes the list of documents Givler reviewed in developing his affidavit.
Exhibit 3 includes topographic mapping for construction and pre-construction conditions.
Exhibit 4 includes a topographic map showing the location of the former levee.
Exhibit 5 includes the approval letter by Montgomery County.
Exhibit 6 includes the rainfall values used by LJA.
Exhibit 7 includes a meteorology report.
Exhibit 8 includes reported locations of flooded properties.
Exhibit 9 includes the drainage impact analysis submitted by LJA on March 26, of 2018.
Exhibit 10 includes the drainage impact analysis submitted by LJA on August 28, of 2018.
Exhibit 11 includes Givler’s hydrology model for pre-development conditions.
Exhibit 12 includes Givler’s hydrology model for construction conditions.
Exhibit 13 includes Givler’s hydrology model for post-development conditions.
Exhibit 14 includes LJA’s design for detention pond S2, the one north of Village Springs.
Posted by Bob Rehak on March 8, 2020 based on testimony from David Givler PE
922 Days since Hurricane Harvey and 171 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.