Today, I came across an eye-popping presentation by John Blount, P.E.. Blount served as Harris County’s Engineer for decades. He left his position last year after serving the Engineering Department for 34 years. The presentation discussed how new building regs adopted in 2009 (and later amended) reduced damage rates during Harvey by approximately 20X.
Bount’s report, however, pointed out that – at the time of Harvey – 75,000 homes had been built in subdivisions developed in 2009 or later that conformed to the new, more stringent building codes. These homes were in subdivisions that used current infrastructure requirements for drainage and extreme event-flow analysis. Out of those 75,000 homes, only 467 flooded during Harvey, or 0.6%. That’s 20X less than 12%.
But even more impressive, Blount said that not one of those homes suffered substantial damage.
Factors that Made the Difference
After that, Blount’s 22-page presentation gets fairly technical. It deals with regulations that affect:
Elevation above the 100-year flood plain
Acceptable types of foundations in flood hazard areas
Building in floodways including width, depth, bracing and other construction requirements for piers
Where fill can and cannot be used
Detention pond requirements
Coordination with MUDs and Special Districts
Coastal vs. Riverine Flooding
Wind resistance
Elevation above street level and more
Photos reflect changing standards for building in floodways.
Driving around town after reading this report will be an eye-opening experience. Take any one of the factors mentioned above, for instance, elevation above street level.
As I was driving through Aldine last weekend to photograph the new detention basin along Halls Bayou, I was struck by how many homes, businesses, and apartment complexes were built several feet BELOW the street levels.
Page 12 of Blount’s presentation addresses this issue. “If the structure is a single family residence the finished floor shall be a minimum of 12 inches above the highest adjacent natural grade when measured 10 feet from the edge of the slab or 12 inches above the crown of the adjacent street whichever results in the highest elevation.”
Drive down Aldine Bender Road or Aldine Mail Route and look at the driveways that slope DOWN to properties. No wonder so many homes in this area flood.
Posted by Bob Rehak on 3/7/2022 based on a report by the former Harris County Engineer John Blount
1651 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/03/20220307-Screen-Shot-2022-03-07-at-6.45.35-PM.jpg?fit=1200%2C522&ssl=15221200adminadmin2022-03-07 19:07:272022-03-07 19:07:31How New Building Regs Cut Damage Rates During Harvey by Roughly 20X
Last week, the City of Houston started clearing debris from the culverts under Kingwood Drive near Kingwood High School. Local flood-fighter Chris Bloch has been working for years behind the scenes to document drainage issues such as this one and convince local officials to address them.
Un-named and Long-Forgotten Tributary Finally Getting Attention
One of Bloch’s latest investigations has been an uncatalogued and long-ignored channel under Kingwood Drive. It helps drain Kingwood High School into Bens Branch. But it doesn’t show up anywhere on Harris County Flood Control District maps.
Two Feet of Sediment Block Culverts Under Kingwood Drive
Bloch says, “The channel originates at Kingwood High School’s athletic fields. The ditch is narrow and full of sediment and vegetation. Side channels, which empty into this ditch, are also full of sediment and vegetation. This is the only ditch providing storm water drainage from the high school campus.”
The ditch in question passes through three culverts under the Westbound lanes of Kingwood Drive. They are obstructed by 24 inches of sediment and debris. See below.
Blocked culverts under Kingwood Drive are finally being cleared.Photo courtesy of Chris Bloch.
“Debris indicates stormwater runoff from the campus passes over Kingwood Drive due to the poor conveyance capacity of this ditch.”
Chris Bloch, Kingwood Resident and Retired Engineer
“If cleared of sediment, the cross section area of the three culverts would total 60 square feet.“
More Blockages Downstream
After crossing under Kingwood Drive, the ditch funnels water into a 24-inch corrugated plastic culvert. That carries it across the Kingwood Country Club Driving Range. “This cross-sectional flow area of this culvert is only about 5% of the total area of the three culverts that pass under Kingwood Drive,” says Bloch.
Later, as the ditch crosses two fairways on its way to Bens Branch, sediment and vegetation again partially block it. They also partially block the three culverts under Centerpoint’s easement near Bens Branch.
Bloch believes, “Maintenance and improvement of this ditch upstream of these outfalls would significantly improve drainage of the high school campus.”
Ensuring Long-Term Maintenance
“Although the Harris County Flood Control District (HCFCD) has no property rights for this channel, the District may be willing to partner with property owners to improve drainage,” says Bloch. “The original channel was reported to have been installed by Humble ISD (HISD) prior to the existence of the driving range.”
Bloch says he has been communicating with HISD, HCFCD and the City of Houston about the poor condition of this ditch since 2020. “I recently communicated with Mayor Pro Tem Martin’s office about this ditch and spoke with Mayor Pro Tem Martin himself about it. The de-silting is another small step forward for flood mitigation in Kingwood. I appreciate the involvement of Mayor Pro Tem Martin.”
“Recently, HCFCD indicated they would be willing to partner with the property owners of this ditch to improve drainage. Hopefully, once the City completes the sediment removal of the channel on the Kingwood Drive right of way, HISD and the Country Club can get together with the HCFCD to improve drainage across the Country Club property to Bens Branch,” says Bloch.
Posted by Bob Rehak with thanks to Chris Bloch and Mayor Pro Tem Dave Martin
1650 Days since Hurricane Harvey
https://i0.wp.com/reduceflooding.com/wp-content/uploads/2022/03/20220306-Screen-Shot-2022-03-06-at-3.41.40-PM.jpg?fit=1200%2C799&ssl=17991200adminadmin2022-03-06 16:49:082022-03-06 16:49:11City De-Silting Channel Under Kingwood Drive Near High School
Along Halls Bayou, HCFCD is constructing a large stormwater detention basin and making channel conveyance improvements as part of Bond Project C-25. The detention basin will reduce the risk of flooding by taking in excess stormwater during heavy rain events and then releasing it slowly back to the channel when the threat of flooding has passed.
Looking S across Isom Street toward Halls Bayou at far end of detention pond.Photo Taken 3/5/22.Reverse shot. Looking N from over Halls Bayou. Photo taken 3/5/22.At the south end of the detention basin, before Halls Bayou comes out of its banks, water will pour over the wide concrete spillway and fill up the pond. As the level of water in Halls falls, water will go back into the bayou through the twin culverts.
Projected Completion Dates
HCFCD expects to complete construction of the stormwater detention basin during spring 2022 and channel conveyance improvements during fall 2022.
The $6 million stormwater detention basin project (P518-11-00) will provide regional mitigation benefits and also mitigate increased stormwater coming from drainage improvements in the Western Homes subdivision along Aldine Mail Route Road.
The basin will hold 180 acre-feet, or nearly 58.7 million gallons, of stormwater that might otherwise flood homes and businesses. It will be a wet-bottom basin with a vegetated shelf.
Channel Improvement Highlights
North of the basin, HCFCD will shift Tributary P118-21-00 west and enlarge it to increase its capacity. Along Aldine Mail Route Road and north of the road, the channel will be extended as a box culvert system to the Western Homes subdivision. The channel will have a 140-foot top width and 15-foot depth.
How New Building Regs Cut Damage Rates During Harvey by Roughly 20X
Today, I came across an eye-popping presentation by John Blount, P.E.. Blount served as Harris County’s Engineer for decades. He left his position last year after serving the Engineering Department for 34 years. The presentation discussed how new building regs adopted in 2009 (and later amended) reduced damage rates during Harvey by approximately 20X.
Before/After Stats
The Harris County Flood Control District’s (HCFCD) final Harvey report found that 154,170 homes flooded in Harris County during Harvey. HCFCD estimated that was between 9-12% of the structures in the County at the time.
Bount’s report, however, pointed out that – at the time of Harvey – 75,000 homes had been built in subdivisions developed in 2009 or later that conformed to the new, more stringent building codes. These homes were in subdivisions that used current infrastructure requirements for drainage and extreme event-flow analysis. Out of those 75,000 homes, only 467 flooded during Harvey, or 0.6%. That’s 20X less than 12%.
But even more impressive, Blount said that not one of those homes suffered substantial damage.
Factors that Made the Difference
After that, Blount’s 22-page presentation gets fairly technical. It deals with regulations that affect:
For Full Report and an Eye-Opening Experience
To see Blount’s full report on How Building Regs Affected Damage during Hurricane Harvey, click here.
Driving around town after reading this report will be an eye-opening experience. Take any one of the factors mentioned above, for instance, elevation above street level.
As I was driving through Aldine last weekend to photograph the new detention basin along Halls Bayou, I was struck by how many homes, businesses, and apartment complexes were built several feet BELOW the street levels.
Page 12 of Blount’s presentation addresses this issue. “If the structure is a single family residence the finished floor shall be a minimum of 12 inches above the highest adjacent natural grade when measured 10 feet from the edge of the slab or 12 inches above the crown of the adjacent street whichever results in the highest elevation.”
Drive down Aldine Bender Road or Aldine Mail Route and look at the driveways that slope DOWN to properties. No wonder so many homes in this area flood.
To make Blount’s report easy to find in the future, search on the keyword “Blount” or consult the Reports Page under “Construction Regs in Flood Hazard Areas” or “Hurricane Harvey and Flooding” tabs.
It’s bewildering why so many surrounding counties and municipalities have resisted upgrading their building, subdivision and flood plain regs.
Posted by Bob Rehak on 3/7/2022 based on a report by the former Harris County Engineer John Blount
1651 Days since Hurricane Harvey
City De-Silting Channel Under Kingwood Drive Near High School
Last week, the City of Houston started clearing debris from the culverts under Kingwood Drive near Kingwood High School. Local flood-fighter Chris Bloch has been working for years behind the scenes to document drainage issues such as this one and convince local officials to address them.
Un-named and Long-Forgotten Tributary Finally Getting Attention
One of Bloch’s latest investigations has been an uncatalogued and long-ignored channel under Kingwood Drive. It helps drain Kingwood High School into Bens Branch. But it doesn’t show up anywhere on Harris County Flood Control District maps.
Two Feet of Sediment Block Culverts Under Kingwood Drive
Bloch says, “The channel originates at Kingwood High School’s athletic fields. The ditch is narrow and full of sediment and vegetation. Side channels, which empty into this ditch, are also full of sediment and vegetation. This is the only ditch providing storm water drainage from the high school campus.”
The high school building suffered $67 million in damages during Harvey and lost another $10 million in contents.
The ditch in question passes through three culverts under the Westbound lanes of Kingwood Drive. They are obstructed by 24 inches of sediment and debris. See below.
“If cleared of sediment, the cross section area of the three culverts would total 60 square feet.“
More Blockages Downstream
After crossing under Kingwood Drive, the ditch funnels water into a 24-inch corrugated plastic culvert. That carries it across the Kingwood Country Club Driving Range. “This cross-sectional flow area of this culvert is only about 5% of the total area of the three culverts that pass under Kingwood Drive,” says Bloch.
Later, as the ditch crosses two fairways on its way to Bens Branch, sediment and vegetation again partially block it. They also partially block the three culverts under Centerpoint’s easement near Bens Branch.
Bloch believes, “Maintenance and improvement of this ditch upstream of these outfalls would significantly improve drainage of the high school campus.”
Ensuring Long-Term Maintenance
“Although the Harris County Flood Control District (HCFCD) has no property rights for this channel, the District may be willing to partner with property owners to improve drainage,” says Bloch. “The original channel was reported to have been installed by Humble ISD (HISD) prior to the existence of the driving range.”
Bloch says he has been communicating with HISD, HCFCD and the City of Houston about the poor condition of this ditch since 2020. “I recently communicated with Mayor Pro Tem Martin’s office about this ditch and spoke with Mayor Pro Tem Martin himself about it. The de-silting is another small step forward for flood mitigation in Kingwood. I appreciate the involvement of Mayor Pro Tem Martin.”
“Recently, HCFCD indicated they would be willing to partner with the property owners of this ditch to improve drainage. Hopefully, once the City completes the sediment removal of the channel on the Kingwood Drive right of way, HISD and the Country Club can get together with the HCFCD to improve drainage across the Country Club property to Bens Branch,” says Bloch.
To see Bloch’s full report, click here.
Posted by Bob Rehak with thanks to Chris Bloch and Mayor Pro Tem Dave Martin
1650 Days since Hurricane Harvey
New Halls Bayou Detention Pond Rapidly Nearing Completion
Along Halls Bayou, HCFCD is constructing a large stormwater detention basin and making channel conveyance improvements as part of Bond Project C-25. The detention basin will reduce the risk of flooding by taking in excess stormwater during heavy rain events and then releasing it slowly back to the channel when the threat of flooding has passed.
I first covered this project six months ago when construction began. It’s come a long way since then.
Photos of Detention Basin Taken Saturday 3/5/22
Projected Completion Dates
HCFCD expects to complete construction of the stormwater detention basin during spring 2022 and channel conveyance improvements during fall 2022.
The $6 million stormwater detention basin project (P518-11-00) will provide regional mitigation benefits and also mitigate increased stormwater coming from drainage improvements in the Western Homes subdivision along Aldine Mail Route Road.
The basin will hold 180 acre-feet, or nearly 58.7 million gallons, of stormwater that might otherwise flood homes and businesses. It will be a wet-bottom basin with a vegetated shelf.
Channel Improvement Highlights
North of the basin, HCFCD will shift Tributary P118-21-00 west and enlarge it to increase its capacity. Along Aldine Mail Route Road and north of the road, the channel will be extended as a box culvert system to the Western Homes subdivision. The channel will have a 140-foot top width and 15-foot depth.
These projects are part the Watershed-Wide Project Implementation Program for Halls Bayou.
Project Locations
Regardless, activists in Halls claim they get no support from HCFCD and that places like Kingwood get all the flood bond money. As a consequence, the county administrator is revising the flood bond prioritization framework yet again to favor projects in Halls and other low-to-moderate income watersheds.
Posted by Bob Rehak on 3/5/2022
1649 Days since Hurricane Harvey