After months of presentations, discussions, and debates, Manvel city council finally approved a Master Drainage Plan to be made part of the city’s Comprehensive Plan. Council heard a final report from the plan’s author at its last meeting and this week heard from the city’s consulting civil engineer, Dan Johnson.
Johnson has favored the adoption of the Plan since its inception more than one year ago. He likens the Drainage Plan to the Thoroughfare Plan in that the city can work with developers to construct the portion of the road that runs through their project. “The city will have to, at some point in time, connect the dots” but the majority of the cost will be borne by developers coming into the city. Likewise, developers will allocate the required rights of way and construct the necessary improvements to meet the mandates of this just adopted drainage plan.
Johnson attempted to allay concerns expressed by some council members in not suggesting pro-actively meeting the plan, which he described as easily costing upwards of $130 million. Existing homeowners will see no adverse impact and trees will not be destroyed. As development happens the plan will be implemented. The current requirement that no improvement produce a negative impact on down-stream flooding will remain, so any development of any size must prove that sufficient retention is made part of their construction program before any building permits can be issued.
Council member Melody Hanson has been the most vocal skeptic of the plan. She considers it misdirected and favors too much developers and future growth and not enough for the people who live in the city now and are burdened by poor drainage. “It seems so imbalanced to me,” she asserted at a previous meeting. Johnson’s comments and enthusiastic endorsement of the Plan apparently failed to sufficiently remove her doubts as she was the lone dissenting vote on the Plan’s adoption.
The Plan was presented initially in early 2014 and cost the city $50,000. The underlying objective was to provide recommendations for drainage improvements in order to meet continued growth and future needs. It will provide direction on how much right-of-way a project will need to donate or provide as part of the drainage plan for their development.
Two scenarios were proposed in the Plan. The one favored by Dan Johnson as offering greater viability both practicably and politically basically entails a combination of strategies that includes individual on-site detention as the key portion. This scenario would require less land for common drainage flows through bayous, creeks, and reliefs. A second scenario provides for regional detention ponds that would be accessed from developments. This scenario would allow for a more attractive city in that each development would need not engineer a unique detention pond just to manage its impact. It also would allow developers greater flexibility in what and how they can design. Since the portion of the development that would have been required for detention would no longer be necessary more land would be available for the project. The downside to this scenario is that more community property would be required to house the regional detention ponds and the common drainage flows through bayous, creeks, and reliefs would need to be even larger that the first scenario.