U.S. Army Corps of Engineers’ (USACE) hydraulic engineers conducted an aerial tour of the West Fork of the San Jacinto River aboard an Army Blackhawk helicopter. USACE Galveston’s hydraulic engineer Michael Garske narrates the video tour, which is fascinating for its candidness.
Objectives
The tour’s objectives: to better understand the area’s dredging needs and to scope out possible locations for storing the spoils.They identified numerous areas with excessive shoaling that contribute to area flooding and require dredging. Engineers estimate they will need to dredge from 1 to 3 million cubic yards.
Sand weighs about 100 pounds per cubic foot. So a cubic yard (27 cubic feet) would weigh almost a ton and a half. Three million cubic yards of sand would completely fill two and a half Astrodomes.
Results not yet final
So where would they put all this dredged material? Nothing is final yet. But it’s interesting to hear the engineers’ comments as they fly over random locations. See the video tour here.
According to reports from Harris County Flood Control, which is coordinating with USACE, the project is slated to start on June 8 and suppliers are being told they need to complete the project within a year.
Various Possible Scenarios Previously Examined
Here are some scenarios based on data from Brown & Root’s 2000 report on dredging, courtesy of David Seitzinger, a Kingwood engineer. Seitzinger points out that Brown & Root also looked at dredging the West Fork. At the time, Brown & Root estimated that it would take 90 to 120 days to bid and mobilize the project. They estimated that one dredge could remove 5,000 cubic yards per day.
If that formula still holds true, a million cubic yards (the low end figure quoted by USACE) could be removed in 100 days using two dredges. If they need to remove 3 million cubic yards, two dredges would take 300 days.
Seitzinger looked at other options, too. Adding a third dredge cuts dredging time by a third – roughly two months to 200 days depending on volume removed.
Using 3 dredges could complete the project by mid-September – the peak of hurricane season – if they only need to remove 1 million cubic yards. That’s the best case scenario.
Worst case? Using two dredges to remove 3 million cubic yards would complete the project around the end of May in 2019.
Of course none of this considers weather stoppages for hurricanes and other flooding rains. “Obviously the more dredges they can get in the river the better,” says Seitzinger.
The Army Corps plays a central role in many of the ongoing projects that affect Lake Houston. Please note the public-facing information sources that contain updates on their projects, including those in the Lake Houston area.
On May 1, Harris County Commissioner’s Court unanimously approved holding a special election on August 25, 2018 for a $2.5 billion flood-bond referendum. August 25th is the anniversary of Hurricane Harvey which affected an estimated 150,000 structures in the region according to FEMA. Ninety thousand of those structures, 60 percent, were outside the 500 year flood plain.
Clearly, Harris County needs to improve drainage. County Judge Ed Emmett says that money in the bond referendum will address needs in all of the Harris county’s 22 watersheds. However, an exact list of projects included in the bond has not yet been defined.
Guiding Principles for Flood Bond
Judge Emmett says he is committed to both transparency and equity in the flood bond package. Historically, the Humble/Kingwood area has been underfunded. The first report by the Greater Houston Flood Mitigation Consortium found that this area contains 3 percent of the region’s population, sustained 14 percent of the region’s damage during Harvey, and historically has received zero percent of the region’s funding. It’s not zero dollars, but the dollars are so small, they get rounded down to zero percent.
What the Flood Bond Includes
Language in the draft bond proposal states in part, “The proceeds from the Bonds will be used for projects to hold or convey storm water, including land acquisition, including buyouts, and the design and construction of reservoirs, detention/retention ponds, channel improvements, restoration, and other improvements (“Flood Protection”) within the following watersheds and their tributaries…” The list of watersheds and tributaries includes the San Jacinto river and three of its tributaries including Cypress Creek, Spring Creek and Luce Bayou.
The proposed bond would increase county taxes a maximum of approximately four cents per $100 of assessed valuation.
If, at this time, I were compiling a list of local projects to mitigate our area’s flooding, the projects would include:
Additional upstream detention
Additional dredging not currently being covered by the Army Corps, i.e., the East Fork and internal drainage ditches
Additional gauges to provide earlier and more accurate warnings before the next flood
Adding tainter gates to the Lake Houston dam, to lower the level of the lake in anticipation of major storms, so that we can shed water faster and earlier to provide an additional buffer against flooding
Partnering with the SJRA on projects that their watershed-wide flood prevention study identifies, especially those that can help the greatest number of people.
Others may have different opinions. What do you think? Contact me through the web form on the contact page.
Posted by Bob Rehak
May 3, 2018, 247 days since Hurricane Harvey
00adminadmin2018-05-03 21:18:522018-05-03 21:18:52Harris County to Vote on $2.5 Billion Flood Bond Referendum on Harvey Anniversary
If you missed the FloodWarn Workshop at Kingwood College on 5/1/18, you missed a lot of helpful information. All four FloodWarn Workshop presentations are now posted in one PDF in the reports section of this web site or via this link.
National Weather Service
Rainfall during Hurricane Harvey
Katie Landry-Guyton, Senior Service Hydrologist/Meteorologist from the National Weather Service-Houston/Galveston office, talked about various types of floods, then focused on river flooding. She discussed the various types of forecasts and warnings NWS has to help you understand levels of risk. She also discussed details of how NWS formulates forecasts. For weather wonks and flood victims, it’s a must-see.
Harris County Flood Control
Jeff Lindner, Meteorologist/Director, Hydrologic Operations Division of the Harris County Flood Control District then discussed the hydrology of Harris County. Within this context, he addressed four types of floodplains in the county, the District’s flood warning system (FWS), inundation mapping/ forecasting down to the street level, and expansion of the District’s gage network.
San Jacinto River Authority
Jace Houston, General Manager of the San Jacinto River Authority (SJRA), talked about the dam operations at Lake Conroe. Specifically, he explained how they made the decision to start releasing water during Harvey. Houston also introduced the SJRA’s new regional flood management initiative.
FEMA
Rounding out the evening, Diane Cooper of FEMA Floodplain Management and Insurance. Cooper, who has posted several times on this blog, is a Kingwood resident. She focused on flood risk, hazard mapping and flood insurance.
Among the surprising facts cited:
The National Flood Insurance Program processed 26,511 claims as a result of Harvey.
55.2% of those claims came from OUTSIDE of the 100 year flood plain.
Only 17% of Houstonians had flood insurance (about 1 in 6)
30,500 structures were in the 1% risk area (100 year flood plain)
29,000 structure were in the 0.2% risk area (500 year flood plain)
City-wide, Harvey impacted approximately 150,000 structures
That means that more structures were impacted outside the 0.2% Risk Area than inside, approximately 90,000.
Cooper cited this last point as the reason why everyone should have flood insurance whether they are officially in the flood plain or not. This was a common theme all night among all four presenters.
They also pointed out that not all flooding comes from rivers. Much flooding comes from streets. Streets in Kingwood are designed as part of the flood retention system. They can deliver approximately two inches of rainfall per hour through the storm drains to the ditches. When the rainfall rate exceeds that, drains will back up into streets and release the water slowly so as not to overwhelm the ditches.
Moral of the story: even if you’re nowhere near the river or a drainage ditch, you can still flood from your street and, therefore, need flood flood insurance.
Take a Video Tour of the West Fork via Helicopter with the Army Corps
Objectives
The tour’s objectives: to better understand the area’s dredging needs and to scope out possible locations for storing the spoils.They identified numerous areas with excessive shoaling that contribute to area flooding and require dredging. Engineers estimate they will need to dredge from 1 to 3 million cubic yards.
Sand weighs about 100 pounds per cubic foot. So a cubic yard (27 cubic feet) would weigh almost a ton and a half. Three million cubic yards of sand would completely fill two and a half Astrodomes.
Results not yet final
According to reports from Harris County Flood Control, which is coordinating with USACE, the project is slated to start on June 8 and suppliers are being told they need to complete the project within a year.
Various Possible Scenarios Previously Examined
Here are some scenarios based on data from Brown & Root’s 2000 report on dredging, courtesy of David Seitzinger, a Kingwood engineer. Seitzinger points out that Brown & Root also looked at dredging the West Fork. At the time, Brown & Root estimated that it would take 90 to 120 days to bid and mobilize the project. They estimated that one dredge could remove 5,000 cubic yards per day.
If that formula still holds true, a million cubic yards (the low end figure quoted by USACE) could be removed in 100 days using two dredges. If they need to remove 3 million cubic yards, two dredges would take 300 days.
Seitzinger looked at other options, too. Adding a third dredge cuts dredging time by a third – roughly two months to 200 days depending on volume removed.
Using 3 dredges could complete the project by mid-September – the peak of hurricane season – if they only need to remove 1 million cubic yards. That’s the best case scenario.
Worst case? Using two dredges to remove 3 million cubic yards would complete the project around the end of May in 2019.
Of course none of this considers weather stoppages for hurricanes and other flooding rains. “Obviously the more dredges they can get in the river the better,” says Seitzinger.
The Army Corps plays a central role in many of the ongoing projects that affect Lake Houston. Please note the public-facing information sources that contain updates on their projects, including those in the Lake Houston area.
Online: www.swg.usace.army.mil
DVIDS: www.dvidshub.net/units/USACE-GD
Twitter: www.twitter.com/USACEgalveston
Facebook: www.facebook.com/GalvestonDistrict
Posted May 5, 2018
248 Days since Hurricane Harvey
Harris County to Vote on $2.5 Billion Flood Bond Referendum on Harvey Anniversary
On May 1, Harris County Commissioner’s Court unanimously approved holding a special election on August 25, 2018 for a $2.5 billion flood-bond referendum. August 25th is the anniversary of Hurricane Harvey which affected an estimated 150,000 structures in the region according to FEMA. Ninety thousand of those structures, 60 percent, were outside the 500 year flood plain.
Clearly, Harris County needs to improve drainage. County Judge Ed Emmett says that money in the bond referendum will address needs in all of the Harris county’s 22 watersheds. However, an exact list of projects included in the bond has not yet been defined.
Guiding Principles for Flood Bond
Judge Emmett says he is committed to both transparency and equity in the flood bond package. Historically, the Humble/Kingwood area has been underfunded. The first report by the Greater Houston Flood Mitigation Consortium found that this area contains 3 percent of the region’s population, sustained 14 percent of the region’s damage during Harvey, and historically has received zero percent of the region’s funding. It’s not zero dollars, but the dollars are so small, they get rounded down to zero percent.
What the Flood Bond Includes
Language in the draft bond proposal states in part, “The proceeds from the Bonds will be used for projects to hold or convey storm water, including land acquisition, including buyouts, and the design and construction of reservoirs, detention/retention ponds, channel improvements, restoration, and other improvements (“Flood Protection”) within the following watersheds and their tributaries…” The list of watersheds and tributaries includes the San Jacinto river and three of its tributaries including Cypress Creek, Spring Creek and Luce Bayou.
The proposed bond would increase county taxes a maximum of approximately four cents per $100 of assessed valuation.
This Houston Chronicle article explains more about the flood bond proposal.
Improvements This Area Could Use
If, at this time, I were compiling a list of local projects to mitigate our area’s flooding, the projects would include:
Others may have different opinions. What do you think? Contact me through the web form on the contact page.
Posted by Bob Rehak
May 3, 2018, 247 days since Hurricane Harvey
FloodWarn Workshop Presentations Now Online
If you missed the FloodWarn Workshop at Kingwood College on 5/1/18, you missed a lot of helpful information. All four FloodWarn Workshop presentations are now posted in one PDF in the reports section of this web site or via this link.
National Weather Service
Rainfall during Hurricane Harvey
Katie Landry-Guyton, Senior Service Hydrologist/Meteorologist from the National Weather Service-Houston/Galveston office, talked about various types of floods, then focused on river flooding. She discussed the various types of forecasts and warnings NWS has to help you understand levels of risk. She also discussed details of how NWS formulates forecasts. For weather wonks and flood victims, it’s a must-see.
Harris County Flood Control
Jeff Lindner, Meteorologist/Director, Hydrologic Operations Division of the Harris County Flood Control District then discussed the hydrology of Harris County. Within this context, he addressed four types of floodplains in the county, the District’s flood warning system (FWS), inundation mapping/ forecasting down to the street level, and expansion of the District’s gage network.
San Jacinto River Authority
Jace Houston, General Manager of the San Jacinto River Authority (SJRA), talked about the dam operations at Lake Conroe. Specifically, he explained how they made the decision to start releasing water during Harvey. Houston also introduced the SJRA’s new regional flood management initiative.
FEMA
Rounding out the evening, Diane Cooper of FEMA Floodplain Management and Insurance. Cooper, who has posted several times on this blog, is a Kingwood resident. She focused on flood risk, hazard mapping and flood insurance.
Among the surprising facts cited:
Cooper cited this last point as the reason why everyone should have flood insurance whether they are officially in the flood plain or not. This was a common theme all night among all four presenters.
They also pointed out that not all flooding comes from rivers. Much flooding comes from streets. Streets in Kingwood are designed as part of the flood retention system. They can deliver approximately two inches of rainfall per hour through the storm drains to the ditches. When the rainfall rate exceeds that, drains will back up into streets and release the water slowly so as not to overwhelm the ditches.
Moral of the story: even if you’re nowhere near the river or a drainage ditch, you can still flood from your street and, therefore, need flood flood insurance.
For more interesting tidbits, download and review all four FloodWarn Workshop Presentations.
Posted May 2, 2018
246 Days Since Hurricane Harvey