The discovery and identification of defects and issues in septic systems is one of the intended benefits of the requirement in the SSR and SPM to have routine maintenance performed by an Authorized Person. When septic systems fail, there is an urgency to make repairs in a timely fashion due to the health hazards associated with them. This learning task will outline the nature and common procedures involved in repairing an existing Type 1 septic system.

Damaged Concrete Septic Tanks

If properly constructed and installed, concrete septic tanks should last as long as the buildings they serve. If a problem occurs, it is usually due to one of the following reasons:

• Poor installation techniques: improper bedding and compaction can cause the tank to settle unevenly and develop cracks
• Manufacturing defects: These can sometimes occur and may not be visible upon pre-installation inspection
• Mechanical damage: rough handling when being installed or heavy traffic over the installed tank can cause it to crack or collapse
• Corrosion: the anaerobic process inside the tank emits hydrogen sulfide gas, and when this mixes with oxygen from the air, hydrochloric acid is produced. This forms at and above the waterline and causes the concrete to spall or flake off over a prolonged period. This continues until the tank wall is so badly compromised that repair or replacement is required.

Concrete Tank Repair

If repair is warranted, the tank must first be exposed, and the lid removed. It is pumped out, cleaned, and allowed to dry. A ladder should be used to allow easy access and egress. An empty tank, even with the lid removed, can be considered a “confined space,” and WorkSafe regulations for confined space entry must be strictly adhered to. Cracks or defects in the tank are then filled with cement or crack filler and allowed to cure. The tank’s inlet and outlet should also be inspected at this time for possible damages needing repair. Once repaired, the tank can be put back into operation.

Damaged Plastic and Fiberglass Septic Tanks

Polyethylene and fiberglass tanks are lighter and easier to handle than are concrete tanks. They are built to withstand normal handling in transportation and installation, and if installed and cared for properly, should last decades. When damage occurs, it can usually be attributed to:

• A manufacturing flaw
• An event in handling, such as a puncture from a forklift
• An installation event, such as improper backfill, uneven compaction under it, or being dropped from a crane

Polyethylene Tank Repair

Before any repairs are contemplated, the tank manufacturer should be consulted. Any repairs must follow their recommendations for safety and liability purposes. Regulations may require that repairs made to plastic tanks should be performed by qualified technicians using specialized equipment. Fusion (heat) welding can effectively repair cracks in polyethylene tanks, as can an epoxy adhesive.

Fibreglass Tank Repair

Repairs to fibreglass tanks can be fairly easy because fibreglass resin bonds to itself quite readily, as this is the same procedure that created the tank to begin with. Repair kits containing resin, a catalyst, rollers, fibreglass sheet material and instructions are available in many sizes. The repair process is quite messy, so appropriate PPE is a must, especially proper gloves that protect the worker from harmful activated resin and sharp glass fibres that must be manipulated by hand. As with the concrete and polyethylene tank repairs, the tank must be pumped out, cleaned, and allowed to dry before repairing. Plastic and fibreglass tanks have access openings rather than removeable lids, so confined space entry procedures will need to be followed.

Regardless of the type of tank, repairs should only be attempted by qualified people after consulting with the manufacturer. If a tank cannot be reliably repaired, it must be replaced.

Damages to a Distribution Box

Because of their size and relative cost, distribution boxes are more likely to be replaced than repaired. Minor cracks in a large concrete D-box may prove less costly and onerous to repair than replace, and if so, follow the same procedures as for concrete septic tank repairs. Damaged plastic D-boxes will most commonly be replaced.

Damages to Field Piping

Field pipe failures are difficult to pinpoint. A careful examination using a pipe camera is usually a necessity, and if used in conjunction with a sonic locating device, any issue such as a break or a root intrusion can be accurately located. Repair of those issues is usually accomplished by replacement of the piping, so excavating equipment will be a must. If the issue at hand is a result of improper installation, much piping and possibly the entire field may have to be replaced. If only a localized issue, a short section of replacement pipe may be all that is required. Shovels and possibly larger excavating equipment may be needed, as well as replacement pipe and clean gravel, as the excavation process may result in contaminating the gravel with cover soil.

If the drain field has become blocked by the accumulation of excessive biomat, the two choices possible for repair are to either dig up the field and replace it, or to “shock” the field. Shock treatment entails the introduction of biological additives into the septic system to help fast track the digestion of organic waste. The products will introduce billions of specific bacteria and enzymes that can clean and restore the drain field by consuming the biomat. This would be the most cost-effective way to restore the field, but water flushed into the system from the house would have to be severely restricted in order to give the enzymes and bacteria the time needed to get the field working again. This option may not be viable if the age of the system suggests that the field has reached the end of its expected life, and field replacement is warranted.

Remember that any repairs to septic tanks or components will involve an AP, who must endorse and record the repair, although not all repairs will require the AP to file (report) them to the local Health authority.

Self-Test 6