During a called work session, the Madison City Council took another step in its ongoing effort to bring the city's stormwater system up to par on May 17.
City Engineer Aaron Wadley and Rodney Way of Inversa Systems – the city's engineering firm hired to assess the condition of stormwater infrastructure – spoke to the council about issues found during the assessment.
Way said Inversa conducted an inventory of stormwater structures and conveyances and looked at the condition of both.
Way said that Inversa's study included 3,975 structures: inlets, outlets, headwalls, end walls, end sections, catch basins, junction boxes, manholes, flumes, etc. The study also evaluated 3,573 stormwater conveyances: box culverts, circular pipes, ditches, elliptical pipes, pipe culverts, swales, trench drains, streams, and dual-inlet connections covering a total length of 60 miles.
Way said that 5% of the structures Inversa was able to examine seemed to be in poor condition, 41% appeared to be in good condition, and 15% were in fair condition. The condition of 39% is still not known because Inversa could not enter the structures and assess conditions. More evaluations using robotic cameras and other methods will be required.
Among conveyances, 59% were listed as in good condition, 10% as fair, 4% as poor, and 27% as yet unknown.
"Overall, the city's drainage systems are in pretty good shape, considering its age," Way said.
However, Inversa recommended that Madison conduct maintenance on 44% of the stormwater system and continue monitoring 19%. Thirty-seven percent has yet to be thoroughly evaluated. Way said maintenance could mean something as simple as cleaning, removing vegetation, or making small maintenance-related repairs.
Inversa recommended that Madison conduct maintenance on 47% of its conveyances, while 23% had deficiencies that need further investigation.
Inversa found up to 25% blockages in several pipes but said those were relatively minor. Blockages at or above 25% need to be addressed much sooner.
Way said that when pipes become totally blocked, the water can pile up on the road, damaging the road infrastructure and costing the city even more money. The assessment said Inversa found 306 conveyances that were 26-50% blocked, 201 conveyances that were 50-75% blocked, and 187 that appeared 100% blocked.
Twenty-nine examples of severe erosion and 395 examples of moderate erosion were uncovered.
Way also said 238 examples of cracks or joint separations and 48 examples of pipe damage were found.
Wadley said a more thorough investigation using robotic cameras and technicians entering some areas could reveal more information about the infrastructure.
Similar results were found for the city's conveyances.
Way said the short-term cost to remove debris and clean the system over the next year would be around $1.2 million, with another $1.4 million over the next four years mainly dedicated to maintenance. Overall, Way said the cost of maintaining the stormwater system would approach $7 million over the next seven years.
Wadley said the city could perform some of the work and save more than $2 million on the total cost.
Funds could come from TSPLOST, LMIG, federal grants available through GDOT, and others through the U.S. Senate.
"Through the good work of Inversa and Aaron Wadley, we are positioning ourselves to get grants," Klimm said. "This will be very expensive, but it's expensive because we have deferred maintenance we haven't done in the past. I give this mayor and his council extraordinary credit for saying we need to deal with this issue once and for all deal with this issue. The systems aren't getting any better; they're all getting worse, and they need to be addressed in a timely fashion."
City staff have been working on a stormwater ordinance and utility to be established under the Public Works Department. The ordinance and utility will be implemented over four years.
Council would set a base rate for residential customers, while commercial rates would be billed as a flat rate plus a fee per 1,000 square feet of impervious surface on a business property.
Klimm said Madison needs the stormwater utility ordinance to provide for future maintenance.
"We've heard the pleas from some of our residents, and they deserve a response," Klimm said.