Floods
 FLOODS AND FLASH FLOODS-Fact Sheet
EMERGENCY INFORMATION
Floodwaters can be extremely dangerous. The force of six inches of swiftly moving water can knock people off their feet. The best protection during a flood is to leave the area and go to shelter on higher ground.
Flash flood waters move at very fast speeds and can roll boulders, tear out trees, destroy buildings, and obliterate bridges. Walls of water can reach heights of 10 to 20 feet and generally are accompanied by a deadly cargo of debris. The best response to any signs of flash flooding is to move immediately and quickly to higher ground.
Cars can be easily swept away in just 2 feet of moving water. If floodwaters rise around a car, it should be abandoned. Passengers should climb to higher ground.
DANGER ZONES
Floods and flash floods occur within all 105 counties in Kansas, although some areas of the state are more susceptible. Communities particularly at risk are those located in low-lying areas, near water, or downstream from a dam.
WHAT IS A FLOOD?
Floods are the most common and widespread of all natural disasters--except fire. Most communities in Kansas can experience some kind of flooding after spring rains, heavy thunderstorms, or winter snow thaws. Floods can be slow, or fast rising but generally develop over a period of days.
Dam failures are potentially the worst flood events. A dam failure is usually the result of neglect, poor design, or structural damage caused by a major event such as an earthquake. When a dam fails, a gigantic quantity of water is suddenly let loose downstream, destroying anything in its path. WHAT IS A FLASH FLOOD?
Flash floods usually result from intense storms dropping large amounts of rain within a brief period. Flash floods occur with little or no warning and can reach full peak in only a few minutes.
DID YOU KNOW...Individuals and business owners can protect themselves from flood losses by purchasing flood insurance through the National Flood Insurance Program. Homeowner's policies do not cover flood damage. Information is available through local insurance agents and emergency management offices.
Flooding has caused the deaths of more than 10,000 people since 1900. Property damage from flooding now totals over $1 billion each year in the United States.
More than 2,200 lives were lost as a result of the Johnstown, Pennsylvania flood of 1889. This flood was caused by an upstream dam failure.
Nearly 9 of every 10 presidential disaster declarations result from natural phenomena in which flooding was a major component.
On July 31, 1976, the Big Thompson River near Denver overflowed after an extremely heavy storm. A wall of water 19 feet high roared down the Big Thompson Canyon where many people were camping. 140 people perished and millions of dollars of property were lost.
Flood Safety
In an average year, more than 130 people are killed nationwide by flooding and flash flooding, with flood-related damages exceeding $3.5 billion. In October 1998, flash flooding killed a dozen people in just a few hours in and around the Kansas City area. In September 2003, flash flooding killed 6 people in a small area on the Kansas turnpike.
Floods can take several hours to days to develop.
Flood Watch
When a flood watch is issued move your furniture and valuables to higher floors in your home. Make sure your car’s gas tank is full in case an evacuation notice is issued. Check your Family Disaster Kit.
Flood Warning
Listen to local radio and TV stations or NOAA weather for information and advice. If told to evacuate, do so immediately and turn off water, electricity and gas at the main valve or switch.
Flash flood can take only a few minutes to a few hours to develop.
Flash Flood Watch
Be alert to signs of flash flooding and be ready to evacuate on a moment’s notice. Listen to local radio and TV stations or NOAA weather for information and advice.
Flash Flood Warning
Evacuate immediately! You may have only seconds to escape. Act quickly! Move to higher ground away from rivers, streams, creeks, and storm drains. Never try to cross water-covered roads. Do not drive around barricades. If your car stalls in rapidly rising waters, abandon it immediately and climb to higher ground. If on foot, do not attempt to walk through floodwaters. Keep children and pets away from floodwaters, storm drains, and sewers. They could be sucked down a drainage tube.
What Can I do Now?
Know your risk. Do you live or work in a floodplain? Check the frequency of flooding in your area by contacting your local floodplain administrator.
Reduce potential flood damage by raising your furnace, hot water heater, and electric panel if they are in areas of your home that may flood. Consult with a professional to see if further damage reduction measures can be taken.
Prepare a Family Disaster Kit.
Check to see if you have insurance that covers flooding. If you are interested in purchasing flood insurance, call 1-888-CALL-FLOOD.
Keep insurance policies, important documents, birth certificates, marriage licenses, and other valuables in a safe-deposit box.
Family Disaster Kit
Your kit should include:
First aid kit and essential medications
- Canned food and can opener
- At least three gallons of water per person
- Protective clothing, rainwear, and bedding or sleeping bags
- Battery-powered radio, flashlight, and extra batteries
- Special items for infants, elderly, or disabled family members.
Identify where you could go if advised to evacuate. Choose several locations. Anticipate a Flood
Signs to watch for:
- Unusually hard rain over several hours or steady substantial rain over several days.
- Rains in conjunction with a spring thaw.
- Listen to your local radio and TV stations or NOAA weather.
Sandbags
Sandbags can be used to fill gaps in a permanent protection system, to raise an existing levee or to build a complete emergency levee.
Sandbags alone, when filled and stacked properly can hold back floodwater, but they are most effective when used with polyethylene (plastic) sheeting.
The bags may be burlap or plastic. Plastic bags can be reused; burlap bags tend to rot after use.
HOW TO FILL SANDBAGS
Fill the bags one-half to two-thirds full. The bag, when filled, should lie fairly flat. Over-filled bags are firm and don't nestle into one another; tight bags make for a leaky sandbag wall. Tying is not necessary
HOW TO STACK SANDBAGS
Stack sandbags so the seams between bags are staggered. Flip the top of each bag under so the bag is sealed by its own weight
SANDBAG BARRIERS
Short Sandbag Walls
- For walls four bags high or less, a simple vertical stack can work. Bolster the wall on the dry side every 5 feet with a cluster of bags or by providing other support.
- You may use the building to support a short vertical stack.
- Vertical stacks are used to block doorways also.
- Caulking weep holes on brick veneer buildings can slow the passage of water into a building, but water will pass through the brick itself unless it has been sealed or the building has been wrapped. Blocking doors and weep holes is not a reliable flood protection method.
Sandbag Levees
- Where you need protection from water deeper than 2 feet, the stack of sandbags should look more like a levee.
- To incorporate 6-mil plastic sheeting into the stack, first lay the sheet along the ground where the outside edge of the sandbag levee will be. It should be 6 mils or heavier, and three times as wide as the intended height of the levee. As you add bags, bring the sheeting up between them in stair-step fashion.
- You can add plastic sheeting to the face of a sandbag levee instead of weaving it between the bags (see diagram). In either case, don't stretch the plastic; it should be slack wherever it isn't completely supported by the bags.
- Add height to the levee by adding bags to the inside and crown.
- A bonding trench will help prevent the levee from sliding.
- When blocking an opening, the plastic sheeting should overlap the permanent structure at least 2 feet on each end. Continue the sandbagging a couple of feet beyond the opening in front of a permanent wall or levee to get a good seal.
Cost & Considerations
Sandbags are inexpensive and are often provided by a community government free of charge. Filling, carrying and stacking them is hard, time-consuming work. When planning a levee, floodwall or other protection system that involves last-minute activity, think about how much time you have to get ready for the water. Some people have two days; some only two hours.
If you plan to rely on sandbags, stockpile sand on your property. It should be relatively free of gravel and covered to protect it from animals and erosion. If you're depending on the community for sand and sandbags, take your own shovel when you go to the distribution site.
Tips
Be sure you can install the system in the amount of time you have to prepare for a flood.
Keep the necessary materials on hand (sand, sandbags, a shovel, polyethylene sheeting, caulking).
Polyethylene sheeting will improve the performance of any sandbag barrier.
When trying to close an opening in a brick floodwall, stuff the grooves with caulking. Cotton caulking, like that used in wooden shipbuilding; will be fairly easy to remove after the flood. A permanent or temporary floodwall or levee is not a complete protection system. You must take additional steps to prevent back-flow of floodwater through plumbing.
Even good systems leak; water seeps in underground; rain may fall inside your barrier. Have a pump to remove this water.
Before each flood season, have a practice run: find the materials; test the pumps.
Have an evacuation plan. Decide in advance when you will abandon a flood fight and save your life.
Sewage Disposal Following a Flood
WHAT WILL HAPPEN?
In an emergency such as a flood, sewer lines will probably be damaged and become inoperable. Sewage may backup and broken water lines may become contaminated by sewage.
If stoppage in sewer lines is suspected or obvious, discontinue discharge of wastewater in house or building sinks and drains and stop flushing toilets. Avoid contact with any overflow wastewater or sewage.
IF I CAN’T FLUSH THE TOILET, WHAT CAN I USE?
- Large extra-strength trash bags (double bags) may be placed in water tight plastic or metal containers, with tight fitting lids, or used as liners in toilets. Household disinfectant can be used for odor control. Final disposal can be by burying or by sanitary sewer when notified by public health officials.
- Dig a latrine or trench two to three feet deep. This can be used to bury human waste. Spread a thin layer of powdered lime or dry chlorine bleach and a layer of earth each time it is used.
- Portable camp toilets, RV toilets, porta-potties, etc., may be used.
- High occupancy complexes such as apartments, condominiums, and office buildings should consider making arrangements to obtain commercial chemical toilets.
WHAT ABOUT SEWAGE OVERFLOW IN MY HOUSE?
Wash all contaminated areas with detergent and water, then rinse with sanitizing solution of one-tablespoon household bleach (5.25% sodium hypochlorite) to each gallon of water.
Be sure to clean and sanitize all contaminated areas—pay special attention to cooking utensils, work surfaces and other surface areas such as floor and walls which your family and pets may come in contact.
Reclaim Precious Heirlooms and other Items from Floodwaters
Floodwaters leave significant structural devastation in their wake, but sometimes the most wrenching losses are the smallest-personal items such as heirlooms, photographs, textiles and books. With proper handling, however, some of these items may be reclaimed from the floodwaters.
Handle wet photos carefully; the surfaces may be fragile. Wet photos may be rinsed in clean water and sealed in a plastic garbage bag with a tie or a zip-lock type plastic bag. If possible, put wax paper between each photo. If a freezer is available, freeze the photos immediately. Later, photos may be defrosted, separated and air-dried.
If no freezer or refrigerator is available, rinse wet photos in clean water and dry them, face up, in a single layer on a clean surface (a table, window screen or clean plastic laid out on the ground). Don’t dry photos in direct sunlight. Don’t worry if the photos curl as they dry. A photo expert can be contacted later about flattening them.
Valuable textiles, such as quilts, laces, needlework or tapestries, will be weaker and heavier when wet and will require extra care. Wear plastic disposable gloves, protective clothing, goggles, and if possible, use a respirator while working on flood-damaged textiles.
Do not attempt to unfold extremely delicate fabrics if they fragile layers are stuck together. Wait until they are dry and consult a conservator.
To remove mud and debris, re-wet the textiles with gently flowing clean water or with a fine hose spray. Gently press water out with the palm of your hand. Don’t wring or twist dry. Remove excess water with dry towels, blotting paper or blank newsprint, especially if the dyes are bleeding. Avoid stacking textiles while drying. Reshape the textile while it is damp to approximate its original contours.
Don’t place textiles in sealed plastic bags. Air-dry indoors with the lights on to inhibit mold and circulate the air with air conditioning, fans and open windows. Use a dehumidifier in the room with the wet textiles and drain the collecting container often.
If heirloom items are broken or begin to fall apart, place broken pieces, bits of veneer and detached parts in labeled open containers. Don’t attempt to repair objects until completely dry or, in the case of important materials, until you consult with a professional conservator.
Remove wet paintings from the frame but not from the stretcher. Air-dry; face up, away from direct sunlight.
If the books are underwater or soaking wet, pick up each one with both hands and place it in a non-paper container (milk crate, wire basket, etc.) so it can be transported safely to an area where it can dry. Keep the book closed while you move it; wet books are very fragile. Remember: the wetter the book, the heavier it is and the more likely to be damaged by rough handling.
The best way to dry books is with cool, dry, circulating air. Never dry them by using an oven, microwave hair dryer or iron. If the volume is very wet, place it flat on a clean table or bench that is covered with absorbent material (paper towels, blotters or un-inked newsprint) between sections of pages. Don’t distort the binding, though. Change the sheets, as they become wet. To speed drying, change the location of the blotters each time they are replaced. With books that have coated pages, use waxed paper instead of absorbent sheets between pages.
If the volume is damp or only partially wet, stand it upright on its driest edge with its pages fanned open. If you are using fans to keep the air circulating, make sure the spines or covers are facing the breeze. If needed, insert blotting materials between pages.
Once the book is dry but feels cool to the touch, close it and place it on its side with a slight weight on it. Check regularly for mold growth. You can also freeze the books to be defrosted and dried later, when conditions improve.
Using Valves, Plugs, Caps and Seepage Barriers in Flood Protection
When there is more water outside than inside a floodwall, levee or building, water continually tries to get inside.
Obvious paths of intrusion are sewer drains for the bathtub and toilet and drainage tubes in floodwalls and levees. Floor drains in some areas of buildings also could provide such a path.
Any drain with its inside opening below flood level must be blocked. The drains may not be obvious – such as air-conditioning condensate drains – so look carefully.
Valves
A single valve installed in the main drain line can prevent back-flow through several interior drains. There are advantages and disadvantages to each of the three valve styles:
Flap Valves
Flap valves are the least expensive but the most prone to failure. A bit of trash stuck on the valve gasket can prevent a flap valve from closing completely. The advantage of a flap valve, aside from its lower cost, is that it reduces back-flow without your intervention. A 4-inch PVC flap valve costs about $40
Ball Valves
Ball valves close by turning the valve handle a quarter turn; this rotates a ball within a drain tube to block flow. A 4-inch PVC ball valve costs about $85. This valve provides a more positive closure than a flap and it will seal even in the presence of some debris.
Gate Valves
Gate valves close by turning the handle several complete rotations to slide the gate across the drain tube. Gates provide the tightest closure possible with valves; the metal valve can overcome the resistance of small debris. A manual 4-inch brass gate valve costs around $110. A hydraulically activated gate valve costs about $850.
Installing any of these valves in an existing sewer line is equally difficult, since it requires digging up the sewer line. However, the benefits far outweigh the trouble and cost of preventing unhealthy sewage back-flow, even if you don’t keep surface flood water out of the building.
It may be beneficial to combine a flap valve (for automatic closure) with a ball or gate valve that requires manual closure but provides a more positive seal.
Caps and Plugs for Open-ended Drain Lines
When the outlet of a drain is exposed, as it is with drain tubes through a floodwall or levee, one simple solution to back-flow is to block the line with a threaded or unthreaded cap.
In a closed sewer system, a valve in the outside sewer line should prevent back-flow through tubs, toilets and other plumbed drains inside the building.
If you don’t have a valve, or the valve fails, you may be able to block the drain openings inside the building.
To do that, you’ll need to access the openings. For a tub or floor drain, that may mean removing the strainer. For a toilet, it means removing the toilet. (Don’t forget to turn off the water to the toilet first and disconnect the water inlet to the tank.)
A product sold for plugging a drainpipe is a gripper plug. Tightening the screw causes the plug to expand and “grip” the inner wall of the pipe. A 4-inch plug sells for about $4.
SEEPAGE
The solution to seepage problems, if you have seepage, is to block underground flow with a barrier that increases the distance water must travel through the ground to get past your barrier
TIPS
- Prevent sewage back-flow with a valve installed in the main sewer line.
- For back-flow protection without human intervention, use a flap valve. Back it up with a positively sealing ball valve, gate valve or plug. More elaborate valve systems are available.
- Caps or plugs may be used instead of valves on exposed storm drains to prevent back-flow. Flow is blocked in both directions.
- On open-ended drain tubes, keep valve gaskets, cap seats and threads clean so they will function properly. Know where removable caps are kept.
- In an emergency, prevent sewer back-flow by stuffing a plastic bag full of rags into the sewer pipe at the clean-out.
- Never use pumps and barriers to create a water-level difference of more than 3 feet without proper design by a competent professional.
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