A multi-year study assessing Sherman’s ongoing flood risk revealed a hefty price tag for mitigation strategies that city leaders will be forced to consider during their yearly budgeting process this summer. In total, more than $54 million in projects are needed in the Post Oak Creek Drainage Basin, a 33-square-mile swath of land that includes most of the city.
Over the last two decades, Sherman has experienced a flood approximately every 18 months, with 14 recorded events since 1993, according to the National Climatic Data Center. The worst of those by a large margin struck on June 18, 2007, with the city received 7.6 inches of rain in seven hours. The event was labeled a 50-year flood, meaning the scale of flooding had a 2 percent likelihood of occurrence. The 2007 disaster damaged nearly 400 homes and businesses and apartments and claimed two lives.
The process to generate the flood mitigation report began in 2010 and included four public meetings from 2011 to 2013. The study cost $333,000 to produce, 46 percent of which was paid for by Sherman. The remainder was covered by a grant from the Texas Water Development Board.
“Certainly, having these frequent floods — they’re supposed to be 50- or 100-year floods and they’re happening every 10 years — that’s a driver, so we embarked on this study,” said Sherman Mayor Cary Wacker. “Every city is trying to figure out the most equitable solution to meet the challenges of flooding while not putting the burden on existing business or new business or homeowners to the degree that it is difficult for them to prosper.”
The study broke down mitigation projects into four categories, namely land acquisition, channel improvements, bridge/culvert improvements and storage projects. Sherman Director of Public Works and Engineering Clay Barnett walked the councilors through a summary of the study’s conclusions regarding each category.
Floodplain land acquisition would have the city purchase “repetitive loss properties” that are prone to flooding, converting the lots into green space. The acquisition cost of $8.4 million could be partially defrayed using federal grants in the amount of $5.3 million. The report identified eight phases of acquisition encompassing 52 properties.
Channel improvements, billed at $18.3 million, would use embankments and riprap to bolster the throughput capacity of local waterways. The improvements would be undertaken in three steps along Post Oak Creek. The improvements would extend from the railroad tracks north of Washington Street near Kessler Boulevard to the point where the creek exits the city south of Center Street.
Barnett stressed the importance of flood-related upgrades to transportation infrastructure around Sherman, as a lack of cross-city road access during the 2007 flood proved especially problematic. The projected $13.9 million price tag would go toward building nine new, elevated bridges and widening the culverts underneath. Barnett said the city needs to be wary of not spending capital improvement money to fix-up bridges that officials tag for replacement.
“Here we have (the Center Street bridge). The cost to replace it is $2.7 million, but it needs $145,000 worth of repair. So we need some direction to determine whether or not we should go out and spend the (smaller sum), and how long we’re going to wait until we spend that $2.7 million. We don’t want to spend the $145,000 if we’re going to do the bridge replacement in a few years.”
Council members had numerous questions during Barnett’s presentation on regional storage facilities. Specifically, Council sentiment seemed to agree with Barnett’s assertion that regional storage projects are preferable to on-site detention built by developers on the same lot as new construction.
The study listed seven possible locations for detention ponds, which would increase the city’s ability to absorb storm water and reduce flooding. The two largest would be near residential areas — one location off Houston Street southwest of Wakefield Elementary and the other expanding an existing pond near Fairview Park.
Additional benefits of regional detention cited by Barnett were cost-efficiency, recreational use of the new lakes and improved water quality. The costs of new regional storage facilities was pegged at $13.8 million, $5.4 million of which is grant-eligible.
Barnett also suggested the city find funds to update its floodplain map, which he said would increase business development in some areas and give the city legal grounds to deny it in others. Updated mapping would cost the city $200,000, with an additional $160,000 required to update ordinances and update the city’s land use plan.
After concluding his presentation on the suggested mitigation projects, Barnett loosed several trial balloons regarding funding mechanisms to stimulate Council’s creativity.
Several councilors were intrigued by the concept of a “fee in lieu of detention” policy, which would allow developers to pay into an escrow fund for civic storm water projects instead of building run-off improvements on site. Fee-in-lieu has been implemented in several cities with success, said Barnett, including Austin, San Antonio and Cedar Hill.
“It doesn’t cost the developer any additional money; all it does is put that money in the city’s coffers, and then the city can build that fund and use that to construct future regional detention facilities,” explained Barnett.
Additionally or alternatively, the Council could implement a city-wide Storm Water Utility Fee. The fee would provide a steady source of money to fund priority projects, and would also free up approximately $180,450 from the city’s general fund to finance other efforts, said Barnett. The city would, however, have to fund a $200,000 study by the state before creating the fee. The study would include public hearings during which the public could voice concerns.
While the decisions on which of the study’s proposals will be undertaken — and how they’ll be paid for — won’t come up for formal consideration until the city’s budget process in June, Wacker said having a few months to cogitate on the study’s conclusions will be helpful for city leaders.
“In the budget process, we’ll have a discussion about various funding mechanisms, and perhaps even a combination of those, trying to come up with an equitable way of funding the necessary structures that we need here to mitigate flooding,” said Wacker. “This (study) simply lays out some potential policy changes and some scenarios we can consider. Because it’s a very complex set of problems.”
Concluding the meeting, numerous council members expressed emotions ranging from relief to excitement that the city finally had a list of recommendations in hand, nearly seven years after a portion of the town was underwater.
“It’s a public safety issue, and when people are dying we need to fix it,” said Councilman Tom Watt. “We’ve done nothing on this for a long time. I think we’re showing that we’re ready to be proactive on this; we just have to figure out how to get there. … I think this is a giant step forward.”