On-site Septic and Sewage Disposal Design

We design septic systems for your home, to fit your lifestyle, to protect your family and the environment.

Septic services we provide:

Septic Planning and Design
Installation and Construction Management
Field Review and Inspection
Building Referrals
Registered Covenants
Water Well Variances

Building a new home or planning a renovation? If the property is not serviced by municipal sanitary sewer, we can design, plan and install a new on-site sewage disposal system. If the property is already serviced by a septic system and you are planning a renovation or adding secondary suite we can perform a septic evaluation and determine if the system meets requirements or requires upgrades.

Planning a subdivision? Requirements for property development vary by jurisdiction but generally require a septic feasibility study to confirm each lot can support an on-site septic system. We complete a site assessment, prepare a preliminary septic design for each lot and document the results in feasibility report to support your application.

Our Design Process

1. Site Evaluation

A proper site evaluation is key to the design and provides information to select a suitable, cost-effective treatment system. Our site assessments include a Desk Study and On-Site Evaluation.

The desk study is an important part of the planning process that is often overlooked. The desk study provides useful information about the site and allows the designer to work more efficiently in the field. We first gather information from the owner including legal information about the property, building and building use. We then use our extensive library of maps and online information to identify easements, water bodies, general soil and geological conditions as well as other important information to identify suitable areas for the septic system.

The on-site evaluation is used to accurately determine the conditions present at site. We conduct soils and drainage testing and estimate the seasonal high water table on the property. We confirm the location of onsite and neighboring water wells and environmentally sensitive areas. During the evaluation our staff discusses details of the project with the owner and reviews landscape plans, and potential future add-on’s such as a pool, workshop or rental suite.

2. System Design

The results of the site evaluation and details of the residence/facility are used to design a suitable Type 1, 2, or 3 system. The design is done in accordance with the requirements of the current BC Standard Practice Manual (SPM). We develop a set of design and construction drawings for filing with the Health Authority and use by the installation contractor for construction. Systems designed by Blackstone Engineering can be installed by one of our preferred installers or by a qualified installer hired directly by the owner. This provides flexible cost saving options for the owner. For more information on construction options contact us.

3. Filing with the Health Authority

Once the design is finished, we submit the system design drawings along with the required application form and other documents to the local Health Authority for registration. Once the septic system has been registered construction of the system may begin. Each filing is valid for two years, and construction must be completed within this period.

4. Construction Review

During construction, Blackstone Engineering staff will perform field reviews at pre-determined stages of construction to ensure compliance with critical design assumptions. The inspection stages are clearly identified on the construction drawings. These visits allow the designer to ensure that the system is being constructed in general conformance with the design and to authorize changes if unforeseen site conditions are identified.

5. Final Documentation

Once construction is completed and approved, a record drawing and system operation and maintenance plan is prepared. These, along with a signed Letter of Certification are submitted to the Health Authority. Once accepted by the Health Authority, copies of all the documentation are provided to the owner. The system maintenance is described in the maintenance plan. It is the responsibility of the owner to ensure that the maintenance is completed as prescribed. Failure to carry out the system maintenance can lead to system malfunction, premature failure, and costly repairs. Blackstone Engineering can provide maintenance services if requested.

SEPTIC SYSTEM TYPES

The type of septic system required for your project can vary depending on the intended use of the facility or residence, on-site soil and groundwater conditions, available space for a septic field, and local requirements. Septic systems in BC are divided into three categories:

Type 1

Type 1 systems use a septic tank as the primary means of sewage treatment and are the most basic type of on-site septic. The septic tank consists of two chambers and has a screened effluent filter at the outlet. Depending on site constraints, soil conditions and groundwater levels, Type 1 disposal fields can consist of several types including: conventional subsurface trenches, at-grade seepage bed, or sand mound.

Type 2

Type 2 systems are septic systems that use a primary trash tank and a secondary treatment plant as the means of sewage treatment. Type 2 treatment plants produce a higher quality effluent compared with a Type 1 system which allow for smaller disposal field. In some cases, Type 2 systems are used in jurisdictions that require nitrogen removal. Type 2 systems are common for many of the larger homes currently being constructed around the lower mainland.

Type 2 treatment can employ a variety of treatment methods. Our systems typically use an aerobic treatment processes which uses an air blower to add oxygen to wastewater. This creates an environment for bacteria to thrive and consume the organics in the sewage. Type 2 disposal fields can consist of several types including: conventional subsurface trenches, at-grade seepage beds, subsurface drip or sand mounds.

Type 3

Type 3 systems use a primary trash tank, a secondary treatment plant and incorporate a disinfection system as the means of sewage treatment. Type 3 treatment plants produce extremely high quality, clear, odorless effluent. Type 3 treatment can employ a variety of treatment methods. Our systems are typically use an aerobic treatment processes and an ultraviolet light (UV) for disinfection. Type 3 disposal fields can consist of conventional subsurface trenches, at-grade seepage beds, subsurface drip or sand mounds. Type 3 disposal fields are typically smaller than Type 1 and Type 2 fields. If space is limited, Type 3 systems are sometimes used even when ground conditions allow for a Type 1 or Type 2 system.

In BC, Type 3 systems are required to be designed and overseen by a Professional Engineer.