Out With the Old

A critical step when installing a replacement onsite system is abandonment of the existing onsite system in accord with all rules and regulations

It’s not every day you have an onsite system that needs to be totally abandoned. Still, it’s important to abandon the old system properly when installing a replacement system.

There are several major reasons for this. First, you need to follow your state and local regulations so you do not get blindsided by fines or requirements that force you to go back and redo part of the job. Other reasons are safety for the homeowner and others, and to protect yourself from future lawsuits.

Know and follow

As always, it is your responsibility to know the rules and regulations and follow them. We’ll describe what is important in abandoning a system on our home turf in Minnesota. Your state or county may have different or additional requirements, so if you are not sure — check!

Tank abandonment procedures apply for sewage tanks, cesspools, leaching pits, drywells, seepage pits, vault privies, pit privies and distribution devices. All liquids and solids must be removed and disposed of properly. If that is not part of your regular business, you’ll need to hire a local pumper. Pumping the material to the surface or into a ditch is not proper disposal.

You’ll need to remove and recycle or dispose of any electrical devices. That includes alarm and water level floats and switches. A number of older floats actually contained mercury, which is considered a hazardous waste and needs to be treated accordingly, both to avoid introducing that highly toxic material to the environment and to protect you and your employees from mercury poisoning.

Remove and fill

Abandoned tanks must be removed or, if left in place, crushed and the cavity filled with soil or rock. Any holes left from removal of tanks, privies or distribution devices also need to be filled. It is also im-portant to remove the connection between the building and the tank, if it is not part of the new construction.

We know of a contractor who replaced a system for a commercial establishment but left a previous tank in place, left the connection back to the building, and sealed the outlet to the tank. Then a heavy rain filled the tank, and the water backed up into the establishment, flooding the lower floor. Removal of the connection also prevents future unlawful discharge to the system.

In the case of cesspools, seepage pits and drywells, filling of the cavity is extremely important. People who live in areas where such systems are common are well aware of the safety issues in leaving those open cavities. Hardly a year goes by without some homeowner walking in the backyard and falling into the cavity as it collapses. Often, these trips are fatal. From an installer perspective, you become a lot more cautious after losing a piece of equipment to one of those old pits.

Dealing with drainfields

If the soil treatment and dispersal unit is to be removed, you must handle contaminated materials in a way that prevents human contact. These materials include distribution media, soil or sand within 3 feet of the system bottom, distribution pipes, tanks and soil around leaky tanks. It also includes any soil that received sewage from surface discharge. Septage or any mixed waste must be disposed of or treated according to state, federal or local requirements.

If contaminated material is to be spread or used on-site within one year, it needs to be placed or stockpiled in an area that is protected from erosion and runoff and that meets any local setback requirements from buildings, property lines, lakes, streams or ditches.

A cover of 6 inches of soil material should be placed over the contaminated material. After one year following contact with sewage, the material can be spread on-site and covered with 6 inches of uncontaminated soil or used to fill in abandoned-in-place tanks.

Other contaminated materials, such as pipe, geotextile fabric or rock, should be dried and disposed of in a mixed municipal solid waste landfill.

One last note: Whether your state requires it, or not, keep good records of when and how you abandoned the system. This means even taking photos of the process and the result.



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