Last week FBCLID 2 received 10-13 inches of rainfall in just a few days. The majority of the rain occurred on Tuesday, May 10 with some areas receiving more than 6 inches of rain in under 2 hours. The intensity of these rainfall rates exceeds any previously measured in FBCLID 2, including during Hurricane Harvey. While all this rain was falling, the Brazos River was also at elevated levels that automatically close the flood gates in the levee. When this occurs, all rainfall must by pumped out of the levee. The FBCLID 2 pump stations operated continuously during the event and there were no problems or issues with the pumps.
In contrast, during Hurricane Harvey, FBCLID 2 received more than 30 inches of rainfall. While the total amount of rain was far greater, the intensity of rainfall did not approach the incredible rates experienced last week. Rainfall during Harvey was also spread out over 5 days and not concentrated into a few hours. When Harvey made landfall, the Brazos River was very low so the majority of the 30 inches of rainfall flowed out of the levee by gravity and did not require pumping.
The attached chart displays the water levels inside the FBCLID 2 levee during Hurricane Harvey and the recent May 2019 flood. The chart also displays rainfall rates during both events measured in 15-minute increments. The two horizontal black lines approximate the elevations where street flooding and home flooding occur.
Since Hurricane Harvey, FBCLID 2 studied the causes of and solutions to flooding inside the levee. Design and construction have already started on several improvement projects. The project that will provide the most benefit during future storms of this nature is the addition of a Third Pump Station at the end of Ditch A (generally located behind Clements High School). The dashed red and blue lines on the attached chart estimate the water levels inside the levee if the Third Pump Station was operating during Hurricane Harvey and May 2019.
A project schedule for construction of the Third Pump Station is attached. FBCLID 2 is more than a year into design. The required property for the Third Pump Station has been acquired, and the new pumps have already been ordered. The new pumping facility will be constructed around seven pumps with 1500 horsepower motors that can pump a combined 980,000 gallons per minute. The project is currently scheduled for completion in Spring 2021. The existing pump station on Ditch A has a capacity of 241,800 gallons per minute.
A series of projects are also being designed and constructed to improve drainage and increase rainfall storage inside the levee. A construction project to perform maintenance and channel improvements to Ditches B, C and E is already underway. A project to widen Ditch A and increase its storage capacity is entering design. FBCLID 2 is also looking to partner with Fort Bend ISD and/or Sweetwater Country Club to provide additional storage for runoff during the most extreme rain events.
FBCLID 2 Pump Stations continue to operate normally, and personnel will remain at the pump stations 24/7 throughout the event.
Drainage South of US-59/IH69 (Ditches A, B, C, D, E, and G): Water levels in the ditches are now below elevation 53 feet, a decrease of more than 12 feet from the peak on Tuesday, May 7.
Drainage North of US-59/IH-69 (Ditch F):
Water levels in Ditch F remain at elevation 65.2 feet.
Brazos River:
The Brazos River crested on Friday, May 10 but will stay at elevated levels through the weekend.
Brazos River water did not reach the bottom of the FBCLID2 levee.
The flood gates in the levee are closed, so no water from the Brazos River can enter FBCLID 2.
All rainfall through the weekend will still need to be pumped out of the levee.
Additional rainfall is forecasted for the afternoon of Saturday, May 11. The FBCLID 2 drainage system has been pumped down and has already regained almost all of its storage capacity.
