OSCAR System Considerations Regarding Rising Water Tables

In the septic business, each season of the year brings different challenges and opportunities. Winter months often have lots of rain, which can be problematic. During and shortly after storm events, the amount of water in the ground increases, raising water tables in some areas close to surface grade. Eventually, the accumulated groundwater will migrate off site into streams, rivers, deep aquifers and the ocean.

With a regular septic system (tank and gravel drainfield), the rising and falling of the water table generally doesn’t affect it. Areas with enough soil depth where a simple gravity system can be installed won’t see the water table rise enough to interfere with the system.

Conversely, in areas that have high season water tables, an OSCAR system would be a natural choice. Most OSCAR systems are installed at-grade or at the surface of the ground so they aren’t affected by the high water. The rest of the system (the septic and pump tanks) is below ground. If these parts of the system aren’t installed to be water-tight, they may suffer from groundwater infiltration. 

Because there are so many possible points of leakage, it’s imperative that best practices are used when designing and installing septic systems. There are good quality tank products that, when installed properly, will prevent all water infiltration. Keep the following considerations in mind.

Overwhelming the System

A one-gallon leak per minute will allow 1400 gallons of liquid to enter the system per day. The OSCAR system, like many other sewage treatment systems, is equipped with electronic controls that limit when and how much water can be pumped out of the tanks to the OSCAR. The limit of water that can be pumped is called the design flow. Usually, the design flow is based on how many bedrooms are in the house. This is an indirect indication of the number of people living in the house. Each bedroom is assigned a maximum daily flow. For example, each may have a maximum flow of 120 gallons per day. This means a four-bedroom system might have a design flow of 480 gallons per day. If we have a one gallon per minute leak, it won’t take more than a day to overwhelm the system.

Fixing Leaks

Depending on where the tanks are leaking, it may be easy or very difficult to find and fix a leak. Also, when troubleshooting leaky tanks, it’s imperative to observe the leak. This must be done during high water events. During a high-water event the tank will be flooded, so it will need to be partially pumped below the level of any plumbing connections. Tanks can leak from access opening connections, protrusions through the riser walls, inlet and outlet openings, the seam between the wall and lid of the tank, and from old plumbing under the house. Some houses that were built with a slab on grade will have all the waste plumbing buried under the slab and potentially in the water table.

Using Old Tanks

When older systems are upgraded on existing homes where the original system failed or an expansion is desired, some design engineers will be tempted to incorporate an existing tank within the new system. Too many times the old tanks have imperfections from outdated manufacturing practices or components corroded from use. Either way, the risk associated with old tanks isn’t worth the hoped-for benefit.

OSCAR System Installations in Idaho

Serving Washington, Oregon, Idaho and Arizona


Posted on January 30, 2021 | Published by Ignite Local | Related Local Business

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