Long Term Floodplain Solutions

Elevation of the lowest floor at least two feet above the Base Flood Elevation (BFE) can look significantly different for each property. Most commonly this involves filling-in any basement and installing new foundation or piers to allow the house to sit an a height at least two feet above the BFE. The process of raising a house typically involves separating the main part of the house from any foundation/basement, moving the house off the foundation/basement, removing or retrofitting old foundation/basement, building or reenforcing new house supports, moving the house on to the new elevation supports, and reconnecting utilities and any finishing construction that's needed. 

Pros:

• More resilient to flooding risk
• Less failure points
• Lower floodplain insurance costs
• Potential to create covered parking

Cons:

• Expensive (likely costing tens of thousands of dollars more than $30,000)
• Slow

Wet floodproofing involves allowing water to automatically come into the building during a flood. Most commonly this method is appropriate for things like crawl spaces or storage areas where flooding will cause minimal damage and cleanup can be done quickly after a flood goes down. The process of providing wet floodproofing generally involves some retrofitting to replace materials that will be damaged if exposed to water for 72 hours and construction of ways for that water to get into the structure, typically flood openings. If the area desired to be flooded is not made of the correct materials than that area will need to be rebuilt. 

Pros:

• May be cheaper than other options
• Less stress on foundations/walls (pressure is equalized on both sides of walls during a flood)

Cons:

• Cleanup after floods still required
• Regular maintenance of flood openings required
• Opportunity for failure point during floods if openings get blocked

Relocation involves more than most other options as a new location needs to be determined and purchased before the building can be moved. The building then needs work to become ready to move. The new location will also require work to prepare for the building, typically a foundation or basement needs to be constructed first. Then after the move the structure needs to be placed on the new location and finishing construction is likely needed to tie everything together. Depending on the specific program being used this process could financially fall on the property owner, developer, City, other groups, or mix of more than one of these groups. 

Pros:

• Long term solution to likely flooding
• Could create public open spaces and storage capacity for flood waters
• Can be done along with a remodel project

Cons:

• Expensive (moving a house can cost in the neighborhood of $25,000 per mile to move)
• Lots of coordination needed (the new site needs to be ready when the house is ready to be moved)
• If part of a federally backed buyout the owner will need to retain ownership of both lots until the project is fully completed

Dry floodproofing involves installing materials, always deployed or setup just before a flood, to block water from coming into a building during a flood. This method is not allowed to be used for residential building within the City of Sioux Falls. Most commonly this method is appropriate for things like blocking small openings below the Base Flood Elevation (BFE). Areas like walkouts or underground accesses are more typical users. But systems can be installed along large stretches of an area to create a wall that holds back flood water. If used, the materials used need to be maintained, stored in an organized fashion and known location, staff trained in installation with ongoing practice. It should be noted that there are designs available that require less setup and can automatically deploy during a flood, but maintenance is still needed.  

Pros:

• May be less invasive than other options
• Little to no cleanup after an event

Cons:

• May require additional engineering design and increase cost (the taller the need the higher the expense)
• Regular maintenance required
• May require human intervention to setup before a flood

Levees and floodwalls both create higher ground next to an area that is at risk of flooding during an event. Each style requires maintenance and construction. While installing a levee or floodway may work for some properties FEMA will not allow a building to be completely surrounded by these structures to then remove that structure from the floodplain. These type of improvements are usually done in larger areas by governments due to the costs of design and construction. It is uncommon for individual property owners in Sioux Falls to construct these types of methods to hold back flood waters. Very specific design criteria are required in order to build these improvements to FEMA and the Army Corp. standards. 

Pros:

• Can be done on a large scale to protect large areas
• Generally these improvements can be long lasting

Cons:

• Will require additional engineering design and increase cost (the taller the need the higher the expense)
• Regular maintenance is mandatory
• Will push water up or down stream which may impact other property owners, study required
• City of Sioux Falls requires compensatory storage is provided for the protected area

Demolition may not be everyone's idea of a solution for flooding but removing the structure does remove the possibility of flooding for that structure. Typically demolition is used by governments to remove structures who get impacted by flooding so that the cycle of flooding and repair does not continue to repeat itself. Most often this process is done as part of a property buyout, which can be part of State or Federal grants to help make specific areas handle flooding better. If an individual property owner in Sioux Falls is using demolition most likely it's in connection with a new building being built at that location.

Pros:

• Building will no longer need repairs after floods
• Creates more storage space for flood waters
• Quick process
• No building maintenance

Cons:

• Can be expensive, especially when considering a replacement structure
• Contractor and razing permit required