By: Matthew Gutzwiller, E.I.T.
Hydrology & Hydraulics - Site Development Project Manager
EHRA Engineering was selected for the Harris County Flood Control District’s (HCFCD) Zube Stormwater Detention Basin and Conveyance Improvements project, designed to reduce flooding in the Little Cypress Creek watershed and to redefine floodplain boundaries of Little Cypress Creek, ensuring that low-income housing and commercial development in the region are less impacted by flooding in the future. The project illustrates EHRA’s capabilities in grant funding, specifically U.S. Department of Housing and Urban Development (HUD) funding; coordination with multiple agencies; and designing large-scale multiple phase drainage projects.
“Although the client’s scope did not directly plan on turning the project areas into recreational facilities, EHRA’s design allowed for other entities to make enhancements such as adding a splash pad, frisbee golf course, and walking trail,” EHRA Project Manager Matthew Gutzwiller said. “This otherwise undefined area represents EHRA’s mission to build better communities.”
The Zube regional stormwater detention basin is part of the Little Cypress Creek Frontier Program. Phase 1, completed in 2016, included excavation and fill within the Little Cypress Creek floodplain to establish the ultimate alignment of the south and east berms of the basin.
Phase 2 consisted of analysis and planning for the proposed inline control structure for the detention basin connecting the Phase 1 existing berms. The control structure was designed to be an ADA accessible structure consistent with overall Zube Park recreation uses and was a necessary component to meet requirements of a federal grant program. During design of the Phase 2 conditions, an Ultimate Design Plan was developed for HCFCD approval prior to submitting an individual permit application to the United States Corps of Engineers (USACE). Ultimate Design conditions included deepening the main channel over 5 feet and extending the channel length through natural stable change techniques - the significance of these improvements dictated the need for submitting an individual USACE permit versus the typical process of applying for a general permit.
Shortly after Phase 2 was completed, work began on Phase 3. During this phase, development within the overall watershed slowed and over 20 planned excavation locations had not been excavated, leading to a significant increase in costs for HCFCD. As a result, HCFCD reduced the scope and costs of the project while ensuring that the requirements of the Individual Permit for the channel and buffer around the channel were still met. To support this effort, EHRA worked with HCFCD to provide recommendations and options to meet the current funding limitations for HCFCD fiscal years and assisted with the planning of construction activities to align with funding availability.
During the two-year period before the Independent Permit was issued, EHRA responded to multiple USACE inquiries, including providing a detailed construction schedule with accompanying detailed instructions to outline the period in which the existing channel bottom is disturbed. The USACE’s goal was to minimize the overall length of the permit, the time period in which the construction and plantings must be completed. EHRA worked with the USACE to include plantings that provide habitat opportunities for wildlife within the channel buffer and develop a complex construction schedule that segments the project to ensure the disturbance period of the existing channel and the associated plantings occur within a specific time period to provide the greatest chance for survival.
EHRA prepared bid documents and construction drawings for Phase 3 of the project, which featured the complex scheduling of construction to minimize the period of disturbance within the existing channel in accordance with the USACE Individual Permit conditions.
A federal HUD grant was awarded to the Harris County Community Services Division to help improve conditions for the surrounding low-income community. EHRA coordinated with the Harris County Community Services Division, Harris County Precinct 3 and HCFCD throughout design and construction to ensure not only that grant conditions were met, but that each agency’s constraints and requirements were met. One of the challenges presented with the grant funding involved the coordination needed with the State of Texas General Land Office (GLO) to release funding associated with the grant. A major portion of the review process was ensuring that every environmental requirement and explanation of the requirement was produced and submitted to the GLO.
Phase 3 of the Zube Stormwater Detention Basin and Conveyance Improvements project is awaiting construction with a projected start date of June 14th and has a tentative construction completion of Winter 2022/2023.