Flood Solutions

If you are a flood victim, if your only choice has been to sell at a loss or suffer more flood damage the next time, this might be of interest to you. Photos are included, as separate links, this reduces the time to load this document. You can link to a photo and return to the document at any time.

Personal Flood Wall Facts

This site:
The flood issue:
The home:
The mitigation issue:
A workable solution:
The solution:
The requirements:
Materials required:
Costs:

These data are related to a flood wall constructed December 1996 in Oakville, Grays Harbor County, Washington at 7475 State Route 12, by Collins Company for Dave and Ellen Palmer.

This information is for guidance only. Your costs and requirements will vary based upon your elevation, flood level, terrain, availability of wood and sand, and access to a workforce or volunteers.

This site:

Home is on a knoll 50 feet south of the bank of the Black River. The Chehalis River is about one mile south, and the Black River joins the Chehalis about one and one-half miles further west.

The flood issue:

Flood waters from the Chehalis River overflow north through historical flood ways and eventually fill the area between the two rivers. In the January 1990 flood we had two inches of water in the house. In the February 1996 flood we had over two feet of water in the house. We suffered significantly in this flood and the total cost of repair to the home and property exceeded $30,000.

The typical approach after a flood is to repair and replace the damage. We did that. Then we were faced with the big question: What happens the next time? This led us to some difficult decisions. Since flood damaged homes are virtually worthless and since we still owed money and since we had just rebuilt, how could we protect ourselves and our assets from the next flood?

The home:

The home is a split level with attached two car garage. A professional house mover stated that because the cement floor was poured separately from the house wall that this particular home can not be elevated or moved.

The mitigation issue:

This home can not be moved or elevated. This left few alternatives. Among them were:

Eliminate the lower floor. A professional written estimate came in at close to $30,000. This solution would eliminate the entire first floor, replacing it with concrete walls that would be open to flood waters. This would destroy the entire first floor and garage and wipe out over half the value of the home. The estimate did not include the cost of repairing or replacing the entry way, electrical wiring, water lines, septic line, or heat pump/furnace and heat ducts. This solution was discarded as unworkable.
Concrete flood dike. This was not pursued. The excavation required to allow forms and footings substantial enough to hold a dike seemed unworkable. The slope of the land, to the south would have required an immense amount of fill, which would have eliminated use of the garage and prevented access to other buildings. Concrete dikes would also displace an immense amount of water downstream.
Earthen dike. This was not pursued. The amount of fill required to level the site enough to construct an earthen dike was beyond estimation. Leveling the site would also eliminate the use of the garage and prevent access to other building located by the house. Another concern about an earthen dike was the required maintenance. Earth dikes can be penetrated by burrowing animals and tree roots, both of which can weaken the dike. A dike of the size required would have worsened the flood for residents downstream.
Sell. This is a frequently voiced solution. Since the market value would be less than half of the purchase price this did not seem to be a workable solution.

A workable solution:

During cleanup of the February 1996 flood we saw the flood wall constructed around a lumber yard in Aberdeen. This was a steel wall, driven into the ground. Several telephone calls and conversations with the timber company and the U.S. Army Corps of Engineers disclosed that this was an expensive solution. We were referred to a company on Camano Island. This company, Collins Company, has a new product which was used to build ocean and marina walls.

Working with the owner, John Collins, we identified a potential solution, [photo] which we then selected and installed.

The solution:

Our solution consists of a personal flood wall that surrounds the house. The wall is located three to six feet away from the existing outside wall of the house.

The personal flood wall stands three feet above the grade level of the home. The wall is three - four feet thick (depending upon location) and it extends one to three feet into the ground (depending upon the terrain).The three foot above grade height minimizes the water displaced downstream.

The sides of the personal flood wall are made out of plastic. The space between the sides is filled with sand. So the house is surrounded by a wall three to four feet thick filled with sand. The plastic comes in long sheets and each sheet interlocks with another sheet. This interlock will fill with sand and become water tight. Some small leakage can be expected, but one or two sump pumps should be able to pump that water back over the wall.

The wall height was set at one foot above the record 1996 flood level of two feet. This height is also visually acceptable and one does not feel imprisoned behind it. The top of the wall can hold plants, or be covered with decking. Ivy or some other plant could be trained to grow up and across the outside wall.

Our normal access to the house has been the back and front doors and the garage. Since we did not want to lose this access, temporary openings were designed at the back and the front. These are normally wide open and closed only when a flood is imminent. Closing the openings requires only one person and will take four to eight hours.

The requirements:

A wall of this type consists of [photo] plastic panels, interconnected to each other. Special fittings are used at the corners. The panels are preassembled into lengths which can be handled by the crew. These lengths of panel are held together by pressure treated 2 X 4's. These 2 X 4's run horizontally along the inside top and bottom of each set of panels. (When [photo] filled with sand the wall is indestructible.)

When placed into the trench the inside panel is connected to the outside panel by long threaded bolts. On the outside of each panel, at about the same location as the inside 2 X 4's, a 4 X 4 is installed. This is the lateral support that holds the wall together. The bolt runs through the 4 X 4. The bolts are installed at three foot intervals.

Using this type of wall as a model, the steps required to complete it are:

Work with the contractor to define a site plan for the wall. This includes drawings which show the planned openings and the excavation requirements.
Locate and mark all buried electrical, television, water, septic, downspout lines.
Excavate a trench around the house. The depth will be determined by the terrain. On a flat parcel the depth would likely be one foot. Avoid cutting any of the marked lines.
If utility lines are in the way (too close to the surface), have them replaced by an authorized technician.
Sever all downspout lines. During a flood they will back up.
Install a shutoff valve in the septic tank line. During a flood it will back up.
Remove all dirt (spoils) dug out of the trench. The trench will need to be backfilled with sand.
Build predetermined lengths of flood wall off site.
Move lengths of flood wall into place and connect the sheets. Cut openings where needed to avoid underground lines.
Install threaded bolts connecting the inside and outside wall through the whalers (which provide lateral rigidity to inside and outside wall members).
When entire wall is erected fill the wall with sand. Don't fill in the planned openings.
Backfill the trench with sand.
Compact the backfill.
Remove the walls from the planned opening and build replacement panels.
Install new downspouts which will discharge water over and outside the new personal flood wall.
Pray for a drought!

Materials required:

To protect our home which is 51 feet by 36 feet, we required the following materials:

200 cubic yards of sand
900 lineal feet of pressure treated 2 X 4's
900 lineal feet of pressure treated 4 X 4's
2,300 square feet of Floodguard wall material
40 lineal feet of Floodguard corners

Trenching required a backhoe - front loader for two days, with operator and helper.

Filling the wall required a front loader for three days, plus [photo] five conveyor belts.

Construction of the wall required a crew of four to five people and took 10 days. There were many weather caused slowdowns and delays. We built our wall during a very rainy period and the mud and the ground water slowed down construction and made a hard job very difficult.

Our site, which slopes, required a lot of extra effort. As the panel height increased, it became more and more difficult to handle and install them. A flat site would have been much easier and good weather would have really aided construction.

Because of the terrain at the site, 5 conveyor belts were needed to move the sand into the wall. These belts saved a lot of physical effort but required a lot of attention and care and feeding. Moving each conveyor required four strong people. Putting sand in the conveyors also required the use of a front loader for 3 days.

On a flat site, with open access, one large front loader could likely fill the wall in one ten-hour day.

Costs:

Your costs will vary with the site, terrain, height and width of the wall, as well as the cost of pressure treated timbers and sand in your location.

The cost of Floodguard material for our job, at $7 per square foot (plus tax) was $16,500. The contractor told us that the material cost was one-third of the normal project cost. He was right.

Overall you can expect costs to range from $100 per lineal foot up to $140 per lineal foot of finished wall. If your site is flat and the same height and you can get volunteer help you might be close to the $100 figure.

If you live in a jurisdiction which has applied for FEMA Mitigation Grants (a competitive process) your project might be eligible for consideration. You might already have a Small Business Administration disaster assistance loan. In that case the Small Business Administration might work with you.

Our county did not apply for FEMA grants. We were not eligible for any FEMA consideration. We had worked with the Small Business Administration and they have worked with us. In order to finance this solution it was necessary for us to obtain two second mortgages on our property. One second mortgage is with the Small Business Administration the other is with a commercial bank. This is an expensive solution, but the only one which allowed us to retain our home without fear of future flood loss.

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For more information:
Collins Co.
1232 N. Shore Drive
Camano Island, WA 98292
360-387-9298

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