Virginia Tech recently did a webinar addressing thestrategies for preparing your septic system for storms and flooding. The climate is changing. We’re not going to be able to stop it, so we have to be prepared for the future that is going to arrive. There have always been great storms, but they are forecast to become more frequent and intense.
According to Phillip Brown, professor at Virginia Tech the 1
degree Celsius increase in temperature that we’ve experienced since the
industrial age has produced a 7% increase in the moisture in the atmosphere. More
moisture brings more intense rainstorms. In addition, the likelihood of
flooding has increased. Sea level is 8-9 inches higher than it was in 1880 and rising
faster than in the past. In 2022 sea level was 4 inches higher than it was in 1993. Higher sea
level allows storms to push further inland. More intense storms bring more
frequent flooding to inland areas.
Locally (here in Prince William County Virginia), rainfall
averages approximately 44 inches per year, but varies from year to
year. Climate forecasts are for our region to get wetter with more
intense rainstorms and droughts to get more severe. (ICPRB). The relationship
between climate change and flooding is complex. Shoreline flooding is the
result of land subsidence, sea level rise, building in the flood plain and
storm surge. The most well-established connection between climate change and inland
flooding is that more warming leads to more intense rainfall, which in turn
increases flood severity in the inland areas. Recent data shows that
inland flooding in Prince William County has increased. We can assume that the
flood is coming.
According to Dr. Brown, septic failure can contaminate
groundwater impacting your well and your neighbors, and bring diseases into the
home. Failed septic systems can release excessive nutrients into waterway resulting
in algal blooms and fish kills. Also, failed septic systems can result in
sewage backing up into your house. The best way to make sure your septic system
survives a flood or excessive rain event is to maintain the system. First and
foremost, is to pump your septic tank every 2-3 years. I do not care what the
regulations say. PUMP IT. As a tank fills with solids over the years, the
retention time falls and the open space that usually exists in a tank is
smaller. You need the about 100- 200 gallons of open space a regularly pumped
tank has.
Make sure that the drain field has good grass and ground
cover. Finally, make sure that the manhole covers are sound and secure. This is
to prevent anyone from falling in and keeping some of the flood waters out.
Just before a storm, make sure any drainage ditches are
clear and the water drains away from the house and the septic system. Many
septic systems do not operate on gravity and need pumps to move the effluent
from the septic tank to the drain field. Alternative systems may have many
other components like blowers, filters that require electricity to operate. If
you experience flooding cut the breakers and stop using anything but minimal
water. With a low flow toilet, you have days of flushing in the available space
in your septic tank. That, however, means that you cannot let any other water
down the drain until the system is up and running again.
After flood waters recede septic systems should not be used
immediately. Drain fields will not work until underground water has receded and
the soil has dried out. Whenever the water table is high or your septic drain
field has been flooded, there is a risk that sewage will back up into your home
due to the water pressure from the flooded drain field. Though septic lines may
have broken during the flood it is more likely that the lines were just
submerged.
The only way to prevent a flooded system from backing up is to relieve pressure
on the system by using it less- so do not allow your tank to pump or drain to
the drain field until the soils dry out. Basically, there is nothing you can do
but wait, do not use the system if the soil is saturated and flooded. The
wastewater will not be treated and will become a source of pollution, if it
does not back up into your house, it will bubble up into your yard. Conserve
water as much as possible while the system restores itself and the water table
fails.
Do not return to your home until flood waters have receded. If there was
significant flooding in your yard, water will have flooded into your septic
tank through the top. The tops of septic tanks are not water tight even with
good manhole covers. Flood waters entering the septic tank will have lifted the
floating crust of fats and grease in the septic tank. Some of this scum may
have floated and/or partially plugged the outlet tee. If the septic system
backs up into the house check the tank first for outlet blockage. Remember,
that septic tanks can be dangerous, methane from the bacterial digestion of
waste and lack of oxygen can overwhelm you. Hire someone with the right tools
to clear your outlet tee.
Do not pump out the septic tank while the soil is still saturated or right before
a storm hits. Pumping out a tank that is in saturated soil (or soon to be
saturated soil) may cause it to “pop out” of the ground. (Likewise, recently
installed systems may “pop out” of the ground more readily than older systems
because the soil has not had enough time to settle and compact.) If the tank
pops out, it will pull and damage all the piping and connections. The system
will have to be rebuilt.
Call a septic service company (not just a tank pumping
company) and schedule an appointment in a few days. Do not use the septic
system for a few days (I know) have the service company clear any outlet
blockage, or blockage to the drain field, check pumps and valves and partially
pump down the tank if your soils are not dry enough or fully pump the tank if
the soil has drained enough. The available volume in the tank will give you
several days of plumbing use if you conserve water to allow your drain field to
recover. Go easy the septic system operates on the principals of settling,
bacterial digestion, and soil filtration all gentle and slow natural processes
that have been battered by the storm.
If your yard is unlikely to flood, even with catastrophic
amounts of rain. (My house and septic sit about 20 feet above the rest of the
yard.) You still should conserve water until your septic system dries out.