Stormwater Management in Extreme Events

Dr. Bill Hunt’s talk at the Museum of Natural Sciences in Raleigh on August 9th focused on the historic flooding hurricanes NC has seen in recent years, and what that means for stormwater management. We all remember when 6 feet of water stood on I-40, making Wilmington was an island and closing 3200 roads statewide. Our highways were (in theory) designed for the 1/500 year storm event, but Florence was a 1/2000 year event in Wilmington.

An NCDOT staff member in the audience shared that they worked with NC Division of Emergency Management and the Navy (yes, the Navy) to ensure that Wilmington had adequate supplies. Looking forward, DOT is working with the National Weather Service and others to stress-test our highway system, as well as learning from Louisiana’s experience during Hurricane Katrina to study bridge span vulnerability (many bridges went out during Katrina due to wave action.)

So what does this mean for stormwater management using green infrastructure? Stormwater managers know that green infrastructure has been designed to effectively treat moderate-sized rain events. How can stormwater BMPs / SCMs safely convey or pass larger storms, while still meeting their treatment goals? Dr. Hunt said that we will probably need to design our SCMs to be a bit bigger and made out of more durable materials. Thinking more broadly about green infrastructure, he also emphasized the need for preserving lands that routinely floods as public amenities. Designing parks, ballfields, or urban agriculture areas that can survive being submerged and somewhat battered in storms will allow us to “live with water” better.

Dr. Hunt and others in the audience also emphasized the importance of breaking down our institutional and subject matter silos. Stormwater, transportation, and emergency managers–and developers–can learn from one another about how best to manage risk and maintain the resilience of the systems where we work, play and live.

How are you designing your SCMs and planning land use for extreme events? How are your partnerships with other managers evolving? Leave a comment below about what’s helping you solve these challenges we all face.

Hurricane Florence and the Hazards of Stormwater Runoff

The Atlantic Hurricane season is now upon us for 2018. The season began on June 1st and runs through to the end of November. Although it is possible for storms to form outside of this time frame, we can expect the bulk of the weather to fall in this period. As Hurricane Florence nears the Carolina coast, many local stores are experiencing empty gasoline pumps and barren store shelves. Hurricane Florence will generate 140 mph (225 kph) winds and drenching rain that could last for days. North Carolina Gov. Roy Cooper has declared a state of emergency and prompted those who live on the coast to evacuate inland. While many think a hurricane only harms coastal communities, flash flooding, high winds, tornadoes, landslides, and mud slides can cause incredible damage to inland communities both during and long after a major storm event like Florence.

It is important to understand that even after a hurricane passes through your neighborhood, you could still be at risk. The precipitation that does not soak into the ground where it falls is referred to as “stormwater runoff“, which can continue to accumulate and cause flooding issues for several days after the rain stops. This runoff is incredibly good at picking up whatever it comes into contact with as it travels downward to the lowest elevation, so it can sometimes also contain hazardous substances such as debris, chemicals, oils and grease, sediment, bacteria, and other pollutants.

Contamination of local waterways is a major threat that can arise from heavy rainfall. Runoff may pollute rivers, lakes, aquifers, and other water bodies nearby. This can add chemicals and hazardous substances to water sources that people drink and swim in. Runoff may be harmful for humans or livestock which may attempt to feed off of plants or water sources that have been affected by runoff. When water runs off roofs, yards, streets, and parking lots into storm sewers or directly into waterways, it carries with it sediments that clog streams and reduce oxygen in the water, as well as chemicals that can be fatal to aquatic ecosystems and lead to undrinkable water supplies for humans.

What To Do During Hurricane Florence

To avoid contributing to runoff pollution during Hurricane Florence, residents can take certain precautions such as cleaning up any debris or waste in yards and streets, and refraining from fertilizing and watering yards, or using toxic products directly before the hurricane. Other steps you can take include reducing the amount of impervious surfaces on your property, lining impervious surfaces with gravel trenches, using the water that drains off your roof, replacing lawn areas with native plants, adding organic matter to your soil, planting trees, creating a rain garden, installing berms and vegetated swales, as well as reducing the slope of your yard. It is also important to ensure pet waste is disposed of properly, as pet waste left on the ground can be washed into surface waters, causing significant bacterial contamination and boosting the nutrients to unsafe levels. It is also important to secure septic systems to ensure that waste does not seep into runoff.

Rain is never going away, and neither is human infrastructure. However, growing technologies like permeable pavement, rain garden construction in urban centers, and public education can go a long way in protecting the health of the lakes, rivers, and oceans that so many people and animals call home. By working together to preserve plant life that filters storm water and taking steps in our everyday lives to slow runoff and instead use it for something like a rain garden, we can begin to tackle the problem of stormwater pollution together.

City of Raleigh Hosting Hurricane Season Flooding Series August 28 and 29

The City of Raleigh sees the most flooding impacts from hurricanes in September and October. To help you prepare, the City is holding public meetings that cover:

  • Why flooding happens;
  • What to expect in different areas of the city;
  • What the City does to reduce impacts from flooding; and,
  • Available community resources.

WRAL meteorologist Greg Fishel will be there to lend his expertise as well!

Click on the links below to find out more information about the series – no reservations are required.

Flooding Series: What you Need to Know During Hurricane Season
August 28 at 6 p.m.
Walnut Creek Wetland Center, 950 Peterson St.

Flooding Series: What you Need to Know During Hurricane Season
August 29 at 6 p.m.
Lake Lynn Community Center, 7921 Ray Road

The Importance of Infrastructure in the face of Natural Disasters

Continuing with our lead-up to “Imagine a Day Without Water”, this post focuses on the recent disaster-related impacts of failing infrastructure from Hurricanes Maria and Irma, some of the most powerful storms to hit the United States in many years. There is currently a capital need of $123 billion per year to close the gap between increasing demand and decreasing maintenance of water infrastructure – and this gap is widening every day.

At the intersection of both negligence and disaster-caused infrastructure lies Puerto Rico. The country, recently hit by Hurricane Maria, has very little functioning infrastructure, and many residents will be without power for up to six months. Therefore, they are without access to water and sewer infrastructure as well. Seeing as Maria was the strongest storm to hit Puerto Rico in almost 80 years, it would be easy to assume that the current infrastructure issues are the result of the unprecedented storm. However, as Dr. Yarimar Bonilla, Rutgers professor and Puerto Rican native, points out in a recent NPR segment, the problem started long before with the government’s decision to prioritize paying off debt rather than performing basic maintenance on the country’s electric, water, and wastewater systems. She notes that much of the damage could have been avoided if the proper maintenance work had been done when it was necessary. Now, with the addition of the storm damage, the issue is much more difficult (and costly) to solve. Listen to the full podcast here.

In Florida, Hurricane Irma overloaded local infrastructure, causing physical damage and health risks. Raw sewage and wastewater flooded the streets as a result of failed pumping stations and backed up sewers. Due to overwhelmed and under-maintained infrastructure, rebuilding will take even longer, as efforts can only begin when the area is “clean, dry, and free from potential health hazards.” The situation in Florida points to the necessity of designing infrastructure systems to fit local needs, such as extreme weather. Read more about the affects of Hurricane Irma on infrastructure here.

Keeping our natural waterways clean is important, but so is making sure our manmade water systems stay so as well. Make sure your local, state, and federal officials know you value investing in our nation’s infrastructure!