Tuesday, I posted about three Harris County Flood Control District (HCFCD) floodwater-detention projects in construction on Greens Bayou. But HCFCD and the Army Corps recently completed three more. All three in the latter category started in 2015 – before the flood bond.
Magnitude of Recent Mitigation Investment on Greens
Looking at all six (in construction + recently completed) helps one understand the magnitude of investment in this watershed during the last six years.
The map below shows the locations of the recently completed projects in black; those still in construction are red. This post will focus on #4, #5 and #6 below.
#4: Greens Bayou Federal Flood Risk Management Project
The Greens Bayou Federal Flood Risk Management Project, also known as the Antoine Stormwater Detention Basin, lies just east of the Cutten Basin, discussed Tuesday. The U.S. Army Corps of Engineers Galveston District (Corps) and Harris County Flood Control District broke ground in 2015. Phase I cost $58 million. Phase II cost $21.4 million. And channel improvements cost $5.7.
Phase I included approximately 3.7 miles of channel conveyance improvements from Cutten Road to Veterans Memorial Drive and approximately 108 acres of stormwater detention storage near the intersection of Antoine Drive and Beltway 8.
Phase II construction began in late 2016. It included completion of the north cell of the basin, located north of West Greens Road and excavation of the south cell, which is located south of West Greens Road.
The Corps designed and built the project. It also planted trees, shrubs, and grasses on disturbed areas. These features will improve stormwater quality, support wildlife and provide opportunities for recreational benefits.
West Greens Drive bisects the Antoine basin, dividing it into two parts. However, box culverts connect them and they function as a single detention pond. The completed basin holds approximately 1,650 acre-feet, or 538 million gallons of stormwater. To put that in perspective, it holds a foot of rain falling over a 2.5 square mile area, or half a foot falling across 5 square miles!
As part of a cost sharing arrangement, the Flood Control District purchased the 138-acre detention basin site. HCFCD also acquired other property and easements, and relocated utilities. The District will maintain the basin and channel in perpetuity.
#5: Kuykendahl Stormwater Detention Basin
Kuykendahl Stormwater Detention Basin sits on a 288-acre property near Kuykendahl Road and Ella Boulevard along an unnamed tributary of Greens Bayou.
Contractors removed 3.61 million cubic yards of soil from the site. It holds 2,325 acre-feet, or 757.6 million gallons of stormwater. That’s a foot of rain falling across 3.6 square miles, or half a foot falling across 7.2.
Following construction, contractors planted 22.19 acres of native tree and shrubs, and 12.79 acres of stormwater quality-treatment wetlands. They also created 14.04 acres of other wetlands to replace those impacted by construction.
Native, woody, riparian vegetation stabilizes banks, shades water, and creates habitat for birds.
FEMA awarded $39.2 million to the Harris County Flood Control District, under the Hurricane Ike Hazard Mitigation Grant Program (HMGP), for construction of this and another stormwater detention basin (see #6 below). The Flood Control District contributed matching funds for both projects.
Ceres Environmental Services Inc. constructed the two basins for $63.7 million. Combined, they were the largest construction contract ever managed by the Flood Control District up to that time. The two basins reduced or removed flooding risks and damages from more than 1,100 structures along Greens Bayou. “Avoided damage” exceeds $90 million in every flood.
Both projects (#5 and #6) are part of Progress Greens, a suite of flood damage reduction projects in the Greens Bayou watershed. All projects under the Progress Greens umbrella will function together to reduce flooding risks and damages for residents and businesses within the 213 square miles of the Greens Bayou watershed.
#6: Glen Forest Stormwater Detention Basin
The Glen Forest Stormwater Detention Basin lies southeast of the Kuykendahl Basin on a 160-acre site east of Interstate 45 and slightly north of Beltway 8. See P500-08-00 in the map below.
The Glen Forest Basin project removed approximately 2.15 million cubic yards of soil in three connected cells. The completed basin holds approximately 894 acre-feet, or 291.3 million gallons of stormwater. That’s 1.4 square miles one foot deep or 2.8 square miles a half foot deep.
Basin design included 2.75 acres of native tree and shrub plantings and 0.81 acres of stormwater quality treatment wetlands.
Natural-channel design features, such as those in #5 above, provide environmental and water-quality enhancement.
Regulation Vs. Mitigation
Areas both up and downstream from these ponds have extremely high-density commercial, industrial and residential development. Drive up Kuykendahl or Imperial Valley, for instance, and you will find mile after mile of apartment complexes. There’s little room for water to soak in during rainstorms.
More sensible development regulations that mandated onsite detention ponds when this area was being built might have prevented a lot of flood damage and heartbreak. Mitigating flood issues is always far more expensive, difficult and time consuming than preventing them. And many times, mitigating them after the fact is not even possible because of the shortage of land.
Value of Coalitions and Cooperation
Projects like the three above don’t happen without the combined efforts of elected representatives at the county, city, state and federal levels, plus community groups such as the Greens Bayou Coalition (GBC).
According to Jill Boullion, former director of the GBC, “The GBC advocated for $55 million in USACE funding from 2009 to 2015 for the Antoine Basin (Project #4) alone. We made many trips to DC, Galveston and Dallas to meet with elected officials, US Army Corps, Office of Management and Budget, and others. The Obama administration finally approved the funding! That was my first advocacy project and, boy, did I learn a LOT!!!”
The moral of that story: never underestimate the value of coalitions and cooperation in moving these projects forward.
Posted by Bob Rehak on 4/22/21
1332 Days since Hurricane Harvey