Credit 3.6: Onsite Sewage Treatment
This credit applies to design of onsite sewage treatment systems in order to minimize the release of pollutants to downstream receiving waters.
Onsite sewage systems, also known as septic systems, are particularly common in rural and cottage situations. Waterfront properties, which tend to be smaller and have wetter soils, pose extra challenges for septic systems. Soil conditions can make your system less efficient in treating wastewater and allow harmful pollutants to get into the water body you live beside. As a waterfront resident, please pay particular attention to your septic system.
Where this credit applies
This credit applies wherever waterfront properties are not served by a centralized sewage system and rely to onsite sewage treatment, and where those onsite sewage facilities are being installed, renovated or maintained.
How to proceed
New systems: Installation of new or upgraded onsite sewage systems (OSS) is regulated by health authorities on both sides of the US/Canada border. In Washington State, state law requires OSSs to be designed by a licensed designer and approved by county health authorities. In BC, new or upgraded OSSs must be designed and installed by a professional engineer or registered onsite wastewater practitioner to meet the provincial Sewerage Systems Regulation, and approved by the local health authority. In both places, the authorized installer will provide you with an as-constructed drawing of the system components and a maintenance plan.
To apply for the credit for new systems, submit the installation and maintenance documentation approved by the applicable inspector or authority.
Existing systems: Confirming that an existing OSS meets current standards typically requires an inspection by a qualified professional. In Washington State, San Juan County requires homeowners to have their systems inspected annually for systems within designated sensitive areas (such as shellfish growing areas), and every three years for all other systems. Inspections can be completed by a San Juan Co. licensed wastewater inspectors or certified homeowner. To become a certified homeowner entails attending a county-sponsored inspection and maintenance workshop, a four-hour session offered each year throughout the county.
To apply for the credit for existing systems, submit the inspection documentation signed by the applicable inspector. In BC, inspections may be conducted by a person approved by the Association of Professional Engineers and Geoscientists of BC (APEGBC) or the Applied Science Technologists and Technicians of BC (ASTTBC).
For the bonus point, a maintenance plan for a septic or other onsite sewage system must address the following:
Location of the tank, tank inlet, and drainage field on the property relative to all other buildings and activity areas (part of the site plan described earlier in this guide in the “Existing Conditions Plan” and “Site Design Plan” sections).
The type of sewage system: gravity, pressure distribution, mound, sand filter, or other type.
The date of the last inspection of the system by an authorized inspector, and by whom.
The latest date when the septic tank and pump tank (if applicable) were pumped out.
Annual inspection by you for septic system failure; look for soggy areas over the drain field, sewage smell in vicinity of tank and field, slow drainage from sinks, toilets back up, etc.
Who to call in the case of signs of failure.
Also take note of best management practices in your maintenance plan, such as:
Avoid pouring or flushing into the septic system: for example, oil, grease, disinfectants (kills the bacteria in the system), solvents, paints, caustic cleaners, cigarette butts, sanitary supplies, diapers, condoms, tissue, napkins, tea leaves, coffee grinds, and fats. These can all plug a septic tank or drain field.
Protect the system from physical damage; for example, do not park over the drain field, bury it under landscaping or plastic (it has to breathe), plant trees or large shrubs over or nearby (roots can damage the field).
Do not use septic system additives.
Do not allow roof or perimeter drains or other surface water sources to discharge on or near the OSS.
Do not overload the system with too much water; for example, from a running toilet or leaky faucet.
Do not irrigate or water on or near the OSS.
Do not install a garburator.
This credit offers 2 base points plus 1 bonus point.
|Onsite Sewage Treatment||
|For an existing on-site sewage treatment system: provide recent inspection documentation signed by a qualified inspector. Indicate the location of any existing sewage treatment structures on the existing conditions plan.ORFor a new or replacement on-site sewage treatment system: provide design and installation documentation approved by the local authority. Indicate the location of any new or replacement sewage treatment structures on the site design plan.||
|Prepare and follow a septic system maintenance plan or checklist||
For more information
BC Health. Maintenance and Operation of Sewage Disposal Systems. www.healthlinkbc.ca/healthfiles/hfile21.stm
Regional District of Nanaimo “SepticSmart” program – www.rdn.bc.ca/cms.asp?wpID=1159
San Juan County On-site System Operation and Maintenance Program http://sanjuanco.com/health/ehswaste.aspx
Washington State Regulations – Chapter 246-272A WAC: On-site sewage systems http://apps.leg.wa.gov/wac/default.aspx?cite=246-272a