Every year, wildfires have the potential to impact properties throughout Western Canada. As residents return to their property after a wildfire, they may have questions regarding their onsite wastewater treatment systems (OWTS) and water wells. This article provides general guidance for these items.

Onsite wastewater treatment systems

Since most components of an OWTS are underground, there is typically minimal direct impact from the wildfire. However, some at grade or above ground components could be affected, such as, LFH At-Grade Systems, chambers, cleanouts, tank risers, lids, inspection ports, or electrical junction boxes/control panels for pumps and mechanical systems. If the property owner notices damage to any of these components, a licensed OWTS professional and/or a Compliance Inspector should be contacted for information and recommendations on how to address these items.

Even if the system has escaped fire damage it still may have been impacted by fire suppression activities on the property. If heavy equipment, such as fire trucks, have driven near the OWTS tanks or across any portion of the soil based treatment area, they may have caused damage to system components or caused compaction of the soil. Each could have an effect on the function of the OWTS. If this appears to be the case, a licensed OWTS professional and/or a Compliance Inspector should be contacted for information.

Wildfires will typically reduce the infiltration of rainwater into the soil. The greater the intensity of the heat, the more impermeable the soil surface will become. Although typically only 1 – 5 cm (1⁄2” – 2”) thick, this crust on the soil surface can significantly decrease the recovery of vegetation as well as promote soil erosion of the site. Look for signs of erosion such as loss of soil or gullying and take steps to divert drainage around the soil treatment area. Bales of straw will provide temporary relief, but lightly scarifying the soil and reseeding with grasses is ultimately necessary to help anchor the soil.

With post wildfire recovery efforts, there maybe an opportunity and necessity to protect the OWTS. The area around the septic tank(s) and the soil based treatment area could be protected from traffic and other associated activities to prevent damage to the system. Snow fence or yellow caution tape is suggested.

An inspection by a licensed OWTS professional may include:

• Inspecting all assessable OWTS components (tanks, advanced treatment units, drop boxes, electrical connections, etc.) and assess for damage, whether ash or vegetative debris has entered the system. All sewage tanks should be pumped and cleaned out.
• Check for damage to above and below ground OWTS components. Wet spots, sewage odors, or disruptive sounds from mechanical components may signal structural issues.
• Make sure wastewater moves between the parts of the system as intended.
• Check for damage to piping where pipes enter the home.
• Make sure that inspection ports are free of blockage and damage. Replace and secure access covers as needed.
• Check the soil based treatment area and the area over the septic tank for damage from fallen debris or firefighting equipment. Repair with sod or seeding to provide good plant cover.
• If the OWTS was damaged, a month after the system is restarted, schedule a follow-up visit to check for proper operation.

Water Wells

Like an OWTS, most of the components of the well and water system are underground and should not be directly impacted by fire. However, one should closely examine the above ground components such as the well casing (the “well head”) and electrical wiring for signs of fire damage. Specifically, one should verify that the electrical wiring to the well head has not been damaged. You should also check the sanitary seal on the well head for fire damage. If the well casing was constructed of PVC (Polyvinyl Chloride), it may have been totally melted away by the extreme heat of the wildfire. The casing could be melted as deep as 0.6 – 1.5 m (2’ – 5’) below grade. This is an item that should be addressed immediately by a licensed water well contractor, as this condition may allow contaminants a direct conduit to the drinking water aquifer. All repairs to the well should be conducted by a licensed water well contractor. As with the OWTS, look for signs of erosion and take steps to divert drainage around and away from the well.

Sources:
Excerpts obtained from the Colorado Department of Public Health and Environment publication, “Guidance for Property Owners Impacted by Wildfires with Homes Served by Wells and Onsite Wastewater Treatment Systems”, June 2018

Excerpts obtained from the National Environmental Health Association publication, “Guidance for Septic Systems Before, During and AfterA Wildfire”, April 2019