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.
British Columbia Watershed Security Strategy
COTRA was engaged by the British Columbia Ministry of Water, Land and Resource Stewardship to participate in consultations related to the Watershed Security Strategy. This technical memo was submitted to the Ministry to summarize the discussions and to document technical perspectives relevant to onsite wastewater management and watershed protection.
COTRA Technical Bulletin - Remediation of Soil Dispersal with Hydrogen Peroxide
COTRA has authored a technical bulletin (draft for discussion) examining the potential for remediation of clogged soil dispersal systems through the application of hydrogen peroxide.
The bulletin summarizes peer-reviewed, third-party research and reflects consultations with subject matter experts experienced in the use of hydrogen peroxide for soil dispersal remediation.
COTRA Bulletin - Remediation of Soil Dispersal with Hydrogen Peroxide
COTRA Discussion Paper - Environmental Impact Studies Under the SSR
COTRA has authored a draft discussion paper examining the appropriate scope, level of effort, and recommended procedures for Environmental Impact Studies (EIS) under the BC Sewerage System Regulation (SSR).
This document is intentionally issued as a discussion paper. Its purpose is to support dialogue, critical review, and consensus-building within the onsite wastewater profession, with the goal of informing the evolution of shared, defensible practice.
The paper presents a tiered approach to EIS, scaled to anticipated daily design flow and site-specific risk factors. This approach is intended to assist practitioners, regulators, and decision-makers in applying EIS requirements in a manner that is proportionate, transparent, and risk-based, while remaining practical and affordable.
Consistent with COTRA’s commitment to the One Water approach, the paper emphasizes the importance of understanding and addressing risk to environmental and human health arising from cumulative impacts—whether at the local scale, within a receiving environment, or across a watershed or aquifer. Protecting water resources while supporting long-term system sustainability is a central theme throughout.
Specifically, the paper:
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Describes the relevant regulatory context
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Examines Ministry of Health and Ministry of Environment and Parks guidance related to the Sewerage System Regulation / Municipal Wastewater Regulation jurisdictional flow divide
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Proposes tiered EIS procedures grounded in risk assessment
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Discusses approaches to identifying and addressing cumulative environmental impacts
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Provides recommendations for EIS documentation and reporting
This draft guidance document is intended to initiate and inform professional discussion, with the objective of moving toward greater clarity, consistency, and consensus in EIS practice under the SSR—supporting environmental protection and public health while maintaining system sustainability and affordability.
Ministry of Health/Ministry of Environment and Parks SSR/MWR Jurisdictional Flow Divide guidance document July 2025
Use this link to access the current draft of the Jurisdictional Flow Divide guidance document.
Onsite Sewerage Jurisdictional Flow Divide Interpretation.pdf
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 members 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 field data spreadsheet to record the minimum required information for in situ water table mounding testing.