Private Sewage Disposal: What You Need to Know
Onsite sewage disposal systems are a vital means of handling on-site wastewater for properties that don't have access to mains sewer systems.
If you require an on-site sewage disposal system for your home, business or development there are a number of things you will need to consider to ensure that your system meets all necessary rules and regulations.
The evaluation of a site for on-site sewage systems must be performed by an Approved Designer registered with the Government Service Centre (GSC). Designers must provide proof of their certification or professional designation prior to assessing your land.
Generally, the evaluation will include identifying the location for the onsite sewage system, testing of soil conditions and absorption rate. There should be enough open land available to accommodate the distribution drains forming the drainage field.
Un-serviced building lots require a minimum lot size of 1860 square metres and a width of 30 metres throughout the entire area in which the absorption field is to be installed while semi-serviced building lots require a minimum lot size of 1400 square metres and a width of 23 metres.
These areas must be able to accommodate the septic system while maintaining separation distances and have sufficient space for the installation of a replacement system. The system must be separated from bodies of water, property boundaries, drilled and dug wells, etc.
Ascertaining the condition of soil is one of the most important aspects of onsite evaluation and system design. Testing of soil conditions is normally carried out in order to oversee the laying of distribution drains. The area of land drainage required varies according to the percolation test. At least one test is carried out during adverse conditions, such as during or just after a period of persistent rainfall.
Building lots with slopes in excess of 30% are unacceptable for conventional on-site sewage treatment systems since this can cause a high risk of effluent breakout. Measures therefore need to be taken in order to reduce the slope below 30%. This could include the redistribution of soil to make the ground more level.
The combination of an acceptable average percolation rate, corresponding soil conditions and an acceptable slope, together with all other minimum requirements being met, should produce a suitable site for the on-site disposal system.
Sewage Disposal System Standards
There are a number of requirements that an onsite sewage disposal system needs to meet in order to be installed successfully. The minimum liquid capacity is 2,300 litres and this needs to be watertight so that there are no leakages.
Tanks must be of sufficient volume to serve the number of users. The determination of onsite sewage disposal system size for residential dwellings is based on the number of bedrooms proposed for the dwelling and assumes full occupancy of two persons per bedroom.
Once testing and evaluation is completed, you are required to submit an application. The decision to approve the development of land may be subject to input from various government departments/agencies dependant on the location of the land and the type of development proposed. The Approved Designer, who is acting on your behalf, must provide the Government Service Centre with two complete copies of the water and/or sewage system design.
You or your representative must submit the following documents:
1. A GSC Application to Develop Land, completed and signed.
2. A detailed diagram of the lot:
- lot boundaries (property lines)
- lot size location of adjacent wells and sewage systems separation distances
- existing and proposed buildings ditching brooks & streams
- ponds and other natural water courses
- municipal or private water services
- livestock operations
3. A floor plan for the proposed dwelling/ establishment, including basement and below ground level pipes/plumbing, if applicable.
4. Municipal Approval
5. Results of a percolation test indicating the date the test was performed as well as the name address and phone number of the person responsible for performing the test.
6. Information regarding soil strata and type in the area proposed for installation of the system.
7. Depth of ground water.
8. Design calculations for design of the septic system.
9. Detailed drawings showing all construction details required to install the onsite sewage disposal system, distribution box, absorption trenches and proposed water supply.
10. A profile of the land which accurately describes the grade of the land.
11. A description of the general ground conditions in the area where the system is to be installed.
12. Additionally, dependant on site conditions, adjacent developments.
After the submission, a Certificate of Approval will be completed and provided to you if the application and building site evaluation submission are considered satisfactory.
Aftercare and Maintenance
Once the septic system is installed, you should have the system regularly serviced and maintained. You should never enter an onsite sewage disposal system and should be careful when looking into one since they produce toxic gases.
Most installers offer ongoing maintenance contracts which include regular servicing. Septic pump-out contractors can also inspect your tank for you after the regular sludge pump-out.