This detention facility is designed as a regional mitigation basin strictly for the benefit of the watershed with no availability to be sold or allocated for public of private projects as part of a joint project with the City of Pearland. This area was identified in the Master Drainage Plan and the specific property was found to be available during the design process of the McHard Rd. Extension project. It is approximately 35 acres and the volume will be maximized to provide ultimate benefits to the surrounding community.
The Mykawa Drainage Improvement project includes the installation of a double row of 4′ x 10′ RCB that will enclose the current ditch to the west of Mykawa from Cherry Street to Orange Street. The project also includes the construction of two separate detention mitigation ponds for the proposed improvements, the land for these two ponds has already been axquired as part of this project and is included in the scope of the project. One pond is located adjacent to the BDD4 complex and the other is located north of Oranage Street, generally between the railroad tracks and SH 35.
This project is part of the Texas Water Development Board grant program 75/25 local match agreement. The District was awarded the grant to enclose the ditch with reinforced concrete boxes and to construct mitigation ponds associated with the project. The goal of these improvements is to provide flood relief to the surrounding area and localized flooding which includes the neighborhoods of Willowcrest and Willowick.
The District has identified the need for improvements to the weir structures at the Bailey Detention Pond (south of Bailey; west of Wells Dr.) and the Cowart Diversion Detention Pond (between Veterans Dr. and Wells Dr.).
A drainage study of the Hood Ditch area was completed in August 2017 which identified several projects that would reduce flooding along Hood Ditch. The improvements at the Diversion Pond were included in this study and was used as a guide to scope this project.
The proposed optimization of the existing weir to Bailey Pond has also been identified by observations during rain events and the LOMR for Coward Creek Diversion improvements. These improvements will provide efficient use of the available volume in both ponds and will reduce the flooding risk to residents along the north/south streets between Bailey and CR 100.
The West Lea Drainage Improvements project will be a multi-phased project that will incorporate improvements to the interior of the West Lea subdivision drainage system, the drainage ditch that conveys storm water from the subdivision, and Mary’s Creek which is the receiving stream.
Mary’s Creek will be reconstructed to install in-line storage through benching sections on the north bank of the channel. The extents of the channel benching will start from the weir at the West Mary’s Detention Basin to the channel crossing at Magnolia Pkwy. A total of approximately 3,800 linear feet of benching will be constructed with stop blocks placed at an interval of approximately 500 feet in order to keep the channel conveyance similar to the existing condition, thereby creating additional storage in the floodplain with the benched sections.
The Mary’s Creek benching project will coincide with the rehabilitation of the West Lea Ditch and drainage improvements within the West Lea subdivision. These improvements will not alter the runoff volume from the West Lea subdivision, only the timing of inflow into Mary’s Creek, reducing the contribution of runoff to Mary’s Creek during peak times. The benching section on Mary’s Creek will provide additional capacity without impacting the 100-year storm frequency.