By: Joseph Monroe, P.E.
Starting late Christmas night 2015, the St. Louis metropolitan area was battered with significant rainfall for 72 hours.
The rainfall totals during this period ranged from 6-12 in. across the region. The impacts of this precipitation were exacerbated by soil, which was already saturated by 2-4 in. of rain and a trace of snow, which had fallen three days earlier. The runoff from this event set many river and stream crest records in the St. Louis region, as well as areas downstream, caused significant property damage, triggered landslides, closed several interstates and forced general evacuations in areas that have never previously flooded.
Cleanup and recovery were complicated by subsequent rain and snow, followed by bitter cold over the New Year’s holiday weekend, which lingered for several days, freezing floodwaters in place. Within the Illinois Department of Transportation (IDOT) District 8 (locally known as the MetroEast), roadways, property access and ferries were affected for 20 days by this event. The Missouri side of the St. Louis region encountered longer public impacts, which prompted multi-state response coordination and the development of an Emergency Management Assistance Compact (EMAC) between the Illinois and Missouri departments of transportation to help speed recovery for the region.
Throughout the event, first responders were challenged with numerous water rescues, because many people took significant risks by attempting to drive into flooded areas or to walk through flowing waterways to reach their destinations. Even with these heroic efforts, seven deaths were attributed directly to the flood. Social media platforms proved to be an essential tool for providing real-time emergency information to the public and helping limit community exposure to unnecessary risk.
Unrelenting challenge
Precipitation totals for December 2015 were elevated for the entire Mississippi River basin and were punctuated by a storm that entered the Midwest on Christmas Eve. Rainfall from this event spread east, intensified and centered on the I-44 corridor from northeastern Oklahoma throughout the St. Louis Region, including the MetroEast. The storm’s apex was early evening on Dec. 27, in consequence of which the vast majority of the St. Louis region was under flash-flood watches or warnings. Many areas were affected by flooding for the first time ever during the height of the event’s intensity. One might well imagine the shock and concern of local residents in those areas. Plans to install floodgates and implement other flood management measures throughout the area were scheduled for daybreak on Dec. 28. IDOT and Illinois Emergency Management Agency (IEMA) forces began providing assistance to local agencies in anticipation of a formal State Disaster Declaration. Emergency Operations Centers (EOC) were fully staffed, monitoring and responding to the event. These efforts began in spite of the storm not relenting until late that day.
Additional isolated storms occurred the afternoon of Dec. 29 as the flooding issues for the region began to shift from the areas impacted by the “flash” runoff to those more traditionally known as flood-prone. This required almost constant adjustment to detours and placement of roadway closure signage to guide the motoring public through this ever-changing stretch. Detours began to overlap within the area and required several miles of adverse travel for each detour. Several communities were left with emergency access only, while others were evacuated completely. In fact, the supply of warning signs, barricades, cones and electronic message boards was depleted throughout the St. Louis region. Materials from areas outside the flood-affected area were needed to respond to the changing locations of impactful flooding.
Closures and crests
During this transition, I-70 and U.S. 40 in Bond County, Ill., were closed by backwater from Shoal Creek inundating a significant segment of each roadway. Additionally, I-64 in St. Clair County required lane closures for several hours to manage floodwater from Silver Creek. Although relatively short-lived, these are the first known flood-related closures for each facility. A significant mudslide occurred in Grafton, Ill., forcing the evacuation of multiple homes and businesses, and complicating the closure of S.R. 100 through town. In all, 38 Illinois state-maintained roadways were closed in the MetroEast by early Dec. 30. With numerous other local facilities being closed, multiple evacuations and significant property damage, several Illinois counties were proclaimed a disaster by Gov. Bruce Rauner, and emergency operations centers were responding to citizens’ needs around the clock.
As areas hit by flash flooding began to see some improvement, locations along larger rivers and streams began to experience pain. The Illinois and Mississippi rivers began to enter flood stage and crest projections from Grafton to Thebes, Ill., suggested record crests. Areas of rivers and streams in Missouri also began to eclipse previous record crests. The geographical area impacted by flooding continued to grow and became complicated by winter weather and extreme cold. At times, the flood fight would take a back seat to periodic snow events. Fortunately, each snowfall was minor in comparison to the magnitude of flooding.
Flooding eventually would impact I-44, I-55, I-64, I-70 and I-255 in the immediate St. Louis area. I-44 and I-55 were completely closed for several days just south of the city. DOTs across the Midwest deployed electronic signage and issued social media warnings to encourage travelers to avoid the area. Due to the extent of the soil saturation in certain areas, truck movements were further restricted on roads that remained open, resulting in trucks being concentrated on primary arterial roads in suburban St. Louis.
The closure of the Brussels Ferry and other local access points left only two points of egress for Calhoun County. North of St. Louis, southbound U.S. 67 became impassable by the rising waters of the Mississippi and eliminated access to Missouri from Alton, Ill., across the Clark Bridge. For those living in or near Calhoun County, adverse travel to access St. Louis surpassed 60 miles and increased a one-way trip to as much as 90 miles. (To put this in perspective, the northwestern edge of St. Louis County can be visible in locations throughout Calhoun County on a clear day.) While daily commutes increased by more than one hour each way, the reduced access to emergency healthcare was more worrisome.
In fact, access to basic needs became an issue for many in the region isolated by the flooding. Emergency management teams in both Illinois and Missouri worked to provide generators and fuel to warming centers and coordinate delivery of items most people take for granted on a daily basis, such as water, dry food stuffs, and basic health and medical sundries. On a larger scale, local agencies worked feverishly to protect their infrastructure with sandbags and makeshift barriers. The local efforts resulted in myriad requests through the emergency operations centers in both states. In Illinois, IDOT delivered plastic, sandbags, sand, rock, flares, batteries, fuel, life jackets, generators, pumps and plows, not to mention technical support.
The flooding in the St. Louis region during the 2015-2016 winter set many river and stream crest records for the area.
Records and response
Area rivers and streams crested during the first few days of 2016, setting many new records. The Mississippi River crest surpassed the previous record set during the flood of 1993 by almost 5 in. the evening of Jan. 2, 2016. Many areas started to return to normalcy during the first week of 2016; however, other locations were much less fortunate. The extreme cold froze many places where floodwaters ponded or suffered from not enough of a grade to overcome both subfreezing temperatures and lack of evaporation during the remainder of January. U.S. 67 southbound out of Alton was covered by more than 7 ft of water in places during the height of flooding. While many areas drained, others became covered with thick ice. With the Missouri Highway Department still fighting flooding and icing on I-44 and I-55, U.S. 67 remained closed, affecting Illinois residents, inflicting daily adverse travel, and restricting access to emergency healthcare for many. With the recovery on the Illinois side of the region picking up momentum, Illinois and Missouri entered into an EMAC to specifically address the U.S. 67/S.R. 367 corridor in Missouri. Crews from IDOT District 8 teamed with Missouri DOT to pump, plow, spread salt, place brine and remove debris between West Alton and the S.R. 367 interchange with I-270 in Bellefontaine Neighbors, Mo., for more than three days to reopen the roadway.
The event created many private and public impacts, which often overlapped. All agencies at both state and local levels were stretched in both Missouri and Illinois. As expected, good internal communication was critical to successfully navigating responses through the storm. However, communication outside the normal day-to-day channels proved to be paramount to reducing response times and providing needed supplies to communities affected throughout this incident. The totality of IDOT’s response included:
Numerous media responses (traditional and social platforms providing real-time information);
- 732,000 rolls of plastic;
- 1,003,530 sand bags;
- 10,515 tons of rock;
- 4,546 tons of sand;
- 141 dedicated trucks for transport;
- Deployment and operation of 19 pumps;
- Installation and maintenance of 17 generators;
- 1,149 other miscellaneous requests; and
- Installation, loan and maintenance of signs, cones and barricades too numerous to track.
The takeaway
Several lessons were learned while managing a winter flood. As those who handle highway operation responsibilities will attest, worker history, local knowledge and methodologies which have stood the test of time are often an agency’s biggest resource when dealing with emergencies. Under this winter event, IDOT’s advantage of managing past floods was also occasionally its challenge, as past floods of this magnitude were almost exclusively managed in warmer weather. Simple things such as fuel mixtures, pump and generator operations, and handling of material stockpiles were affected by the weather. After-action debriefings showed most should have been expected when placed in the context of normal winter operations. One advantage the weather provided was a relatively captive public audience. With the many platforms of social media at the agencies’ disposal, they were able to communicate directly to those affected by the event. Feedback received after the event from the public clearly noted an appreciation of all outreach efforts. Further, the public supplemented IDOT and the Missouri Department of Transportation (MoDOT) efforts by forwarding emails, retweeting posts and linking to both DOTs’ websites, which further enhanced delivering crucial information to the traveling public throughout the St. Louis region.
About The Author: Monroe is with the Illinois Department of Transportation.
