2026 10 20 Council Meeting Packet

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The Masterplan’s analysis incorporates FEMA studies, historical USGS stream- gage information, 
TDOT bridge and culvert records, City GIS and engineering plans, field survey, LiDAR, land -use 
information, soil data, and current precipitation -frequency data. HEC -HMS and HEC -RAS were 
used to evaluate watershed runoff and the primary riverine system, while PCSWMM was used to 
evaluate the City's closed storm sewer systems. The models were calibrated to available historical 
information, with an emphasis on  the May 2003 flood. Although additional stream and rainfall 
monitoring would improve future calibration, the Plan concludes that the models provide a 
reliable foundation for infrastructure planning and flood mitigation. 
T
he primary -system analysis identifies several bridge and culvert crossings with inadequate 
capacity or freeboard. Along Oostanaula Creek, bridge crossings received poor or failing capacity 
ratings, while every evaluated Oostanaula crossing was deficient in freeboard. North Mouse 
Creek crossing at Hwy 305 and Decatur Pike perform better  under most events, with 305 being 
more vulnerable to lower frequency intervals storms that  result in overtopping . This is 
particularly problematic as this is a primary corridor in and out of North Athens via exit 52. 
T
he secondary -system analysis confirms significant deficiencies in all three focus areas. The 
Tellico & Towanda Trail area experiences issues beginning with events as small as the two -year 
storm. Leveck to Downtown Athens generally has less than a two -year level of service, with 
substantial capacity problems throughout several branches of the system. Cook Dr south along 
North White Street likewise has less than a two-year level of service, with substantial surcharging 
and flooding along the corridor. The recurring issues are generally attributable to undersized or 
shallow pipes, poor or negative slopes, bottlenecks, elevated tailwater conditions, and the 
incremental way the system developed over time through various additions prior to the advent 
of engineering practices that insisted attention be paid to iteratively upsizing  stormwater 
infrastructure and stormwater best management practices. 
T
he primary -system recommendations  establish a broad strategy for the City's streams, 
floodplains, bridges, and culverts. A central recommendation is that the hydraulic models 
developed as part of the masterplan remain active planning tools rather than static studies. The 
Plan recommends stream gages, rainfall monitoring, periodic channel surveys, and coordination 
with future land -use, transportation, and economic -development decisions.  There are 
opportunities for Athens to partner with other agencies to install and maintain such tools. 
Fo
r deficient bridge and culvert crossings, the Plan recommends prioritizing replacement of 
structures with low levels of service, considering retrofit or deck -raising of structures with 
adequate capacity but inadequate freeboard, and coordinating closely with FEMA and TDOT. 
Because several affected structures are within TDOT rights-of-way, interagency coordination will 
be necessary. 
W
ithin the North Mouse Creek watershed, the Plan focuses heavily on North Mouse Creek 
Tributary 1. Regional Park has experienced substantial sediment accumulation, and dredging was 
advanced into construction. The Plan identifies stream erosion between Layman Road and 
Regional Park Drive as a significant driver  of this sediment and recommends stream restoration 
and bank stabilization to reduce recurring sediment deposition and protect exposed utilities. 
T
hat culminates into the  proposed Layman Road project. Existing culverts experience 
overtopping at relatively frequent storm intervals, including overtopping of the Layman Road 
crossing during approximately a two-year event. The proposed alternative removes a section of 
18
Work Session 
October 12, 2026