Technical Information
On this page you will find information bulletins, reports, and commentary on technical issues produced by COTRA.
If you need further information or would like to discuss any of these issues, please contact us by email.
COTRA Projects
Well Setbacks
In 2010, the SSR was amended to include prescriptive standards for well setbacks to sewerage systems and holding tanks.
The Ministry of Health produced a rationale document (PDF) supporting this decision. COTRA has reviewed this and published the following response document:
Response and comment on SSR well setback rationale (PDF)
Subsequently, the Ministry published the following policy statement on "grandfathering" of older systems, specifically for repairs of existing systems originally constructed with less onerous setbacks.
Sewerage System Repair Policy (gov.bc.ca) (PDF)
Composting Toilet and Greywater Guidelines
Guidance for Composting Toilet and Greywater Systems in BC - 2016 (PDF)
COTRA authored this Manual of Composting Toilet and Greywater Practice with funding from the BC Ministry of Health, Health Protection Branch.
COTRA continues to provide technical support and peer review for qualified persons engaged in design and construction of composting and greywater systems.
Individual Projects by COTRA Members
Minimum Dispersal Contour Length
COTRA has analyzed measurements of water table mounding below 43 full-scale tests of soil dispersal systems. This analysis supports reducing the minimum dispersal system contour length required in standards in BC and Alberta and other jurisdictions, at least for soil types common in BC.
COTRA members Michael Payne and Ian Ralston wrote a technical paper on the subject and presented this at the NOWRA 2024 conference in Spokane. NOWRA’s Education and Technical Practices Committee reviewed the paper and approved publishing in the NOWRA conference proceedings.
For a copy of Payne & Ralston (2024), please see:
https://www.nowra.org/Customer-Content/www/CMS/files/24Mega_Paper_LinearLoading_Payne.pdf
Guidelines for Water Table Mounding Testing
COTRA memebers Ian Ralston and Michael Payne authored this Guideline for Water Table Mounding Testing to propose a standardized method for water table mounding testing during design of small onsite sewerage systems, to support validation of custom contour loading rates (linear loading rates).
Ralston and Payne. 2024. Guideline for Water Table Mounding Testing (pdf)
COTRA also developed this water table mounding test field data collection table in spreadsheet format for water table mounding testing, intended to include the minimum required information as a basis for designer's custom sheets.