Flood Control Project

I have received a lot of comments off the blog about the flooding issues in our basement. So I thought I would post a note on what we plan to do.   Water in basements is bad, but for model railroaders it is even more of a concern as our railroads are at risk. 

Background. This house is 25 years old. It is located in an area that was first developed around 1900 to provide housing for workers at Potomac Yard on the RF&P.  Our street is located in a relative flat area that is about 20 feet above the level of the Potomac River and 35 feet above sea level. There is a steep ridge to the west. Water from that ridge drains through this area on the way to the river.  

Note there is no storm sewer in the alley or street by our house. 

We have a drain pipe buried in our back yard that exits to the south west.  Our sump exhausts to this drain. We assumed the drain went to a storm sewer in the alley. But, that is not true.  I recently discovered that the city has posted a map of the sewer lines in this area. When I looked at it I discovered to my surprise that there was no storm sewer in the alley behind my house.  Once the drain leaves my lot line I really don't know where it goes.  I assume it drains west toward the storm sewer three houses down. The ground actually slopes up as you go east toward the river in the alley, so  I doubt it flows that way. 

The basement walls are sound.  They don't leak. Water enters the basement through the the sump and the air conditioner drainage hole.

We have lived here about 18 years. In the past we have not had flooding from rain as long as we had electrical power.  We did have an incident in 2011  where the circuit breaker to the sump popped off and we got some water in the basement. I was home when that happened and was able to flip the breaker and the water quickly drained.

When the basement flooded last summer, we were not home. So we didn't know what happened.  

Recent Observations   In the past three weeks I have been home during several heavy rain storms and have been observing and collecting data on how the water flows in and around our house in a storm. We also had a pipe inspection service check our gutters.  

We now know a lot more about what is happening when it rains. 

First, our gutters are not directing water away from the house. When we tested each gutter downspout with the hose, we can see water flow into the sump instead of away from the house. We had a plumber try to run heavy duty snakes in the underground portions of the downspout drainage and discovered that they are  either clogged or just end  about 6 feet below grade.  

By watching the water accumulate in my sump during a rain storm and doing tests with the garden hose and hot water heater over flow pipe, I have been able to get a better idea of the drainage under the concrete floor and around the footers.  The sump has two pipes that input to it. One is the footer drain. The other drains the A/C condensation pipe, which does create a lot of water in the summer.  These seem to do a good job of routing water to the sump. By the way, the sump is located in the front room of the house in the northwest corner under the  train layout. 

On July  22nd our power went out during a brief but intense rain storm. Our back-up battery-powered pump was not pumping, though it was spinning. The battery level was too low, despite no warning from the control panel. This battery back up system is several years old and needs to be upgraded.  I was able to jury rig the main pump with power from my car and watch it work. It took 2 hours to pump the sump dry. The pump has a capacity of 2600 gallon per hour.  

Water level near HVAC closet

The next day,  we had another massive storm. The power did not go out. We had about 1-2 inches of water in the basement. It was deepest in the HVAC closet. The pump ran for 4 hours and the water level did not change much. By the fourth hour, the water level started to go down. It took another hour to drain the water. That means we pumped around 13,000 gallons of water before the water level  dropped.   There are 7.5 gallons per cu-ft. Our basement is about 1,000 square feet. That means we had the equivalent of 1.7 feet of water in the basement. That is much more than the rain that fell on our house and lot. 

Two things could be happening. First, water is draining into the area under our basement from other sources. Second, our pump is working in a loop- that is, it is pumping water to the back yard where is accumulates and then filters back to the sump. I suspect both are happening, though the second seems more likely and problematic. The fact that water  level did not drop in the basement after rain stopped strongly suggests to me that we have a pumping loop.

 

Mulch tide line shows water flood level on back patio

I monitored the water outside and yes, the back yard was flooded with enough water to encroach onto the patio.  Oddly, the patio drained really well and dried very quickly.  Over the years, the landscaping in the back has gotten taller as we added mulch and plantings. I think we have interfered with the drainage pattern. 

The city sent out an email that said the storm on the July 23rd dumped 30 times the water that the city sewer system could handle.  There was widespread flooding. All the neighbors on my block had flooding in their basements to some degree. The good news is that even with this latest rain storm, the water level did not get deeper than 2 inches in the basement. My neighbor 3 doors down was not so fortunate. He got 3 feet of water as runoff from the street entered his basement though an external stair well.  He said the water at the curb was 24 inches deep.  The slight slope of the street from my house to his makes a big difference. 

I have ordered some water tracing dye to further test were the downspouts and sump are exiting. See the next post .

This evening I did an experiment. I put my garden hose in the sump pump output. After about 2 hours, the outlet got saturated and we started seeing a loop. The water from the garden hose was rushing into the sump and was getting pumped right back out.  This tells me that we need to reroute the exhaust from the sump to the front where the drainage will be better.  I also observed that water was rushing into the sump from both the footer drains and from the exterior of the A/C drain pipe. That means water is flowing from locations under my floor other than the footer drains. That is not necessarily bad, but it does mean that a second sump in the HVAC closet would help evacuate water. 

One bit of good news. The new ceramic tile floor was not affected by the flood. We are able to mop and scrub it back to like new condition. 

With this new data I have come up with the following plan. 

1. Redesign the gutter downspouts to ensure they drain away from the house. Drain to the front is preferred, and away from neighbor’s lot line. 

2. Regrade any landscaping that is not sloped away from the house. This is only an issue in the backyard. The front is well graded away from the house.

3. Install a second sump or enlarge current sump so that we have at least 2 @ 1/2HP sump pumps. One pump will exit in existing pipe to the back, one to exit to the front.  I am undecided on whether we need a new battery back up pump. It won't cost much to add and it would provide some redundancy if say the circuit breaker pops. The new sump pumps will be wi-fi enabled so we can monitor their performance and react if power goes out or a pump fails. 

4. Run an electrical line for a new dedicated outlet for the new sump pumps. While I'm at it, install a new wall switch and outlet so I can power my layout with one switch.

5.  Install a natural gas powered 16-22KW whole house generator with automatic cut in during power outages and whole house surge protector.  That way I can run trains in a power outage. 

6. Draft an annual service plan to check all systems and service as needed.