Skip to content
You are here > Home > Your Ministry > Ontario Building Code > Appeals & Approvals > Building Code Commission > Rulings of the Building Code Commission > 2000 > BCC Ruling No. 00-34-766

Follow us

BCC Ruling No. 00-34-766

Email this page

BUILDING CODE COMMISSION DECISION ON B.C.C. #00-34-766

IN THE MATTER OF Subsection 24 (1) of the Building Code Act, 1992.

AND IN THE MATTER OF Clause 8.2.2.3.(1)(a) of Regulation 403, as amended by O. Reg. 22/98, 102/98, 122/98, 152/99, 278/99, 593/99, 597/99 and 205/00 (the "Ontario Building Code").

AND IN THE MATTER OF an application by Mr. Thomas Leitz, Owner, Toronto, Ontario, for the resolution of a dispute with Ms. Robin Allen, Area Manager, North Bay-Mattawa Conservation Authority, Ontario, to determine whether the working capacity of an existing gravity fed septic tank provides sufficiency of compliance with Clause 8.2.2.3.(1)(a) of the Ontario Building Code at Lot 22, Concession 6, Plan 42R-8123, Township of Seguin/Foley, Ontario.

APPLICANT
Mr. Thomas Leitz, Owner
45 Russel Hill Road
Toronto, Ontario

RESPONDENT
Ms. Robin Allen
Area Manager
North Bay-Mattawa Conservation Authority

PANEL
Mr. Bryan Whitehead, Vice-Chair
Mr. Frank Wright
Mr. Bill Fellner

PLACE
Toronto, Ontario

DATE OF HEARING
July 13th, 2000

DATE OF RULING
July 13th, 2000

APPEARANCES
Mr. Thomas Leitz, Owner
Toronto, Ontario
The Applicant

Ms. Robin Allen
Area Manager
North Bay-Mattawa Conservation Authority
The Respondent

RULING

1. The Applicant

Mr. Thomas Leitz, owner, Toronto, Ontario, has applied for a building permit under the Building Code Act, 1992 to construct a new cabin as an addition to his cottage at Lot 22, Concession 6, Plan 42R-8123, Township of Seguin/Foley, Ontario.

2. Description of Construction

The Applicant is proposing to construct a new one-bedroom cabin on his property which already has a three-bedroom Group C - dwelling unit. The proposed construction will increase the number of bedrooms from three to four and the total number of fixture units from 22 to 28. As a result, the daily design sewage flow will increase from 1700 litres to 2400 litres. The total finished floor area will be 225 m2.

The Applicant is not proposing any changes or upgrades to his existing sewage system, which has been installed in 1993. The existing sewage system is described as a conventional Class 4 sewage treatment facility. It has a 4540 litre septic tank and transmits effluent to a 86 m leaching bed by gravity. The leaching bed comprises six four-inch distribution pipes.

The subject site is a cottage property with minimum slope and is covered with grass. The T-time of the native soil is reported to range between five to six minutes per centimetre. The depth to high groundwater table is six metres.

The construction in dispute involves the working capacity of the existing septic tank.

3. Dispute

The issue at dispute between the Applicant and the Respondent is whether the working capacity of the existing gravity fed septic tank provides sufficiency of compliance with Clause 8.2.2.3.(1)(a) of the Ontario Building Code (OBC). According to this Clause the working capacity of a septic tank servicing a residential occupancy must be twice the calculated daily design sanitary sewage flow for that occupancy (however, regardless of the type of occupancy and daily design sewage flow, a septic tank must in no case have a working capacity less than 3600 litres). As a result, based on calculated daily design sewage flow of 2400 litres, the required tank size for the subject dwelling is 4800 litres. The existing tank is a two compartment tank without a siphon or pump. The inside dimensions of the tank, as described by the Applicant, are 2388 mm ( length) by 1523 mm (width) by 1399 mm (depth to the bottom of the outlet). The chamber divider measures as 1523 by 1399 mm with an average thickness of 63.5 mm.

Therefore, at issue is whether the volume of the existing septic tank, when considering its interior dimensions, is adequate for a working capacity of 4800 litres.

4. Provisions of the Ontario Building Code

Clause 8.2.2.3.(1) (a) Septic Tanks

  1. The minimum working capacity of a septic tank shall be the greater of 3 600 L and,
    1. in residential occupancies, twice the daily design sanitary sewage flow

5. Applicant's Position

The Applicant submitted that the working capacity of the existing septic tank exceeds the working capacity attributed to it by the manufacturer.

The Applicant argued that manufacturers typically oversize their tanks to accommodate such things as pump chambers and to allow for bowing of forms and un-level tanks. The existing system is a gravity fed system and does not have a pump chamber. Besides he asserted, based on the OBC definition of working capacity (Article 1.1.3.2.) and information regarding the inside dimensions of the existing tank as provided by its manufacturer, the working capacity of the tank is calculated to be 4 953 litres instead of 4 540 litres stamped on it. As he explained this size has been calculated by subtracting the volume of the chamber divider from the overall volume of liquid accumulated to a depth under the outlet pipe.

Based on this calculation the existing tank meets and exceeds the 4800 litres OBC size requirement for a septic tank to serve a four bedroom dwelling unit with a daily design sewage flow of 2400 litres, he concluded.

6. Respondent's Position

The Respondent submitted that she accepts the working capacity of septic tanks based on the manufacturer=s stamp. She stated that the working capacity of the tank under dispute, as indicated by the manufacturer, is 4 540 litres. If it is not, i.e., if Brooklin and other tanks tanks have a working capacity larger than labelled, installers and regulators should be informed, she argued.

The Respondent then concluded that based on manufacturer's stamp on the existing tank, the existing tank cannot handle the increased calculated flow and is required to be upgraded to an acceptable size as required by the OBC.

7. Commission Ruling

It is the decision of the Building Code Commission that the existing labelled 4 540 septic tank provides sufficiency of compliance with Clause 8.2.2.3.(1)(a) of the OBC on the condition that it is equipped with an effluent filter.

8. Reason/s

  1. The required tank volume to permit the additional building is likely contained within the over-sizing of the tank by the manufacturer.
  2. The addition of an effluent filter, which will remove part of the Suspended Solids and the Biological Oxygen Demand would compensate for any very small tank volume shortfall.

Dated at Toronto this 13th, day in the month of July in the year 2000 for application number 2000-47.



_______________________________________________

Mr. Bryan Whitehead, Vice Chair





_______________________________________________

Mr. Frank Wright





_______________________________________________

Mr. Bill Fellner