Council approves pumped-detention variance for proposed Manvel ER after safety assurances

Manvel City Council approved a design-criteria modification on March 17 to allow pump-assisted detention at the proposed freestanding emergency facility on Highway 6, ending a split Planning, Development and Zoning recommendation. The applicant had requested a variance to permit pumped detention because available outfall elevations on Highway 6 are shallow.

Assistant City Engineer Matt and staff outlined criteria required for pumped systems: nonresidential use; no residences within 1,000 feet of the pump facility; a backup natural-gas generator for the pump system that meets life-safety redundancy; gravity-based detention for at least 50% of required storage; and approval by the relevant drainage district (BDD4). The applicant told council the ER facility would meet those conditions, that pumps are tied to the building’s life-safety generator with automatic transfer within 10 seconds, and that a portable pump would be kept on site in case of an unlikely dual failure.

Councilmembers who oppose pumped detention as a matter of engineering preference nonetheless voted to approve the modification for this site because the project met the ordinance criteria and because staff and the applicant provided multiple safeguards. Mayor Davis noted the approach is site-specific and does not bind council to approve similar requests elsewhere. The vote was unanimous 5–0.

Staff said final permitting will still require drainage-district approval and coordination with TxDOT on outfall and access. The applicant remains responsible for maintenance covenants and agreed to provide the city with the proposed stormwater maintenance plan.