Drainage Improvements Next Target For Jacksonville Storm Resiliency Committee
Jacksonville’s storm resiliency committee looks poised to recommend several changes to city development rules that members hope will improve drainage and reduce flooding.
During Friday’s meeting, Jacksonville’s Storm Resiliency and Infrastructure Development Review Committee (SRAIDRC) unanimously voted to draft and submit legislation recommending specific impervious surface ratios (ISR) for each of the city’s zoning districts.
Impervious surfaces, which the city doesn’t currently regulate, are land areas that repel rainwater and don’t allow it to soak into the ground, such as roads, buildings, housing developments and parking lots. Impervious surfaces can have an effect on streams and rivers in water quality, flow and flooding.
In natural forested watersheds, most rainfall is absorbed into soils, stored as groundwater and then slowly discharged into streams and rivers through seeps and springs. Flooding is less frequent and severe in these conditions because during storms much of the runoff is absorbed into the ground.
According to the U.S. Geological Survey, “as watersheds are urbanized, much of the vegetation is replaced by impervious surfaces, thus reducing the area where infiltration to groundwater can occur. Thus, more stormwater runoff occurs - runoff that must be collected by extensive drainage systems that combine curbs, storm sewers and ditches to carry stormwater runoff directly to streams.”
Put simply, in developed watersheds more water flows into rivers and streams more quickly, increasing the likelihood of more frequent and more severe flooding.
Also on Friday the committee discussed four changes to the city’s Land Development Procedures Manual, commonly referred to as the red book:
- A proposed “Maintenance of Drainage” plan that would identify site-specific methods for maintaining stormwater drainage patterns during the construction phase of a project. Routine compliance inspections would be required, though the city wouldn’t prescribe specific methods. Instead, the owner or project lead would be responsible.
- The expansion of pre-development surveys (required surveys of properties prior to development) to include all of the area extending at least 100 feet beyond the boundaries of developments.
- Inclusion of all rear-lot drainage systems in ongoing development stormwater management certification requirements. This change would also grant city or state officials access to all of these systems for inspection.
- A requirement that once a development project begins (when a site permit is issued or the developer notifies the city) a formal six month inspection report be submitted to the city. Those reports will be required to be submitted every six months until construction is finished.
These proposed additions to the red book would go through the Subdivision Standards and Policy Advisory Committee established via section 654.142 of the city charter.
Committee members were also told on Friday that a previously discussed request for proposal (RFP) has been developed and is now ready for review. That RFP is designed to solicit design professionals or experts to help the city come up with a plan for hardening existing infrastructure. The committee anticipates having that RFP advertised by the end of May.
Public hearings on the bill recently filed by councilmembers Lori Boyer (a member of the SRAIDRC) and Jim Love on the committee’s behalf (2019-0331) will be held on May 28. The ordinance is scheduled to be discussed in committees on June 3 and 4 and will go before the full City Council on June 11, if it’s not deferred.
The SRAIDRC is scheduled to present all of its findings at the City Council’s June 25 meeting - the last meeting with the current group of councilmembers.