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BCC Ruling No. 00-33-765

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BUILDING CODE COMMISSION DECISION ON B.C.C. #00-33-765

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

AND IN THE MATTER OF Sentence 8.6.2.2.(2) and Table 8.6.2.2.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. John Hyjek, Owner, Oil Springs, Ontario, for the resolution of a dispute with Mr. Bob Hexter, Chief Building Official, County of Lambton, Ontario, to determine whether the proposed Whitewater treatment system discharging to the proposed shallow buried trench sewage system designed to be buried in shallow sand fill provides sufficiency of compliance with Sentence 8.6.2.2.(2) and Table 8.6.2.2.A. of the Ontario Building Code at Lot #10, Concession II, County of Lambton, Ontario.

APPLICANT
Mr. John Hyjek, Owner
Oil Springs, Ontario

RESPONDENT
Mr. Bob Hexter
Chief Building Official
County of Lambton

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. Ken Dickson
Dickson Environmental Consulting
Wallaceburg, Ontario
Agent for the Applicant

Mr. Mark Wetering
Junior Planner
County of Lambton
Designate for the Respondent

RULING

1. The Applicant

Mr. John Hyjek, R.R. #3, Oil Springs, Ontario, has applied for a building permit under the Building Code Act, 1992 to install a Class 4 sewage system at Lot #10, Concession II, County of Lambton, Ontario. 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 install a Class 4 shallow buried trench sewage system in order to serve a Group C - residential building currently under construction. The building is described as having two bedrooms, a total of 17 fixture units, and a finished area of 126.34 m2. The calculated daily design sewage flow is 1100 litres.

The proposed system is to consist of a "Whitewater" treatment system with a capacity of 1900 litres per day, a pump chamber and a shallow buried trench system. The shallow buried trench system will consist of four runs of chambers with total length of 40 m. These chambers are to be placed on 150 to 200 mm imported sand fill with a percolation time of less than 10 minutes over a native soil with a percolation time over 125 minutes. The trench system would be covered with a layer of 250 mm pea stone or coarse sand prior to backfilling by the native topsoil. The proposed leaching bed area would be 441 m2 (21 by 21 metres) and the mantle would extend four metres from the pipe. The treated effluent is proposed to be pumped directly from the treatment unit to the distribution pipes for final disposal. The free access sand filter component of the system, as required by the manufacturer and set out as a condition for approving the Whitewater system by the then-approval authority (the Ministry of the Environment) for soils with a percolation time between 50 to 125 minutes is not proposed.

The site is a 40-hectare farm having a minimal slope and is mostly covered with bush. The depth to bedrock or high groundwater table, as described by the Applicant, is 1.8 metres. The percolation time of the native soil is reported to be greater than 125 minutes.

The water to the site is supplied by municipal waterline.

The construction in dispute involves the proposed change in configuration of the Whitewater treatment system.

3. Dispute

The issue at dispute between the Applicant and the Respondent is whether the proposed Whitewater treatment system discharging to the proposed shallow buried trench system designed to be buried in shallow sand fill provides sufficiency of compliance with Sentence 8.6.2.2.(2) and Table 8.6.2.2.A of the OBC (Ontario Building Code).

Sentence 8.6.2.2.(2) sets out standards for the quality of the effluent that is allowed to be discharged to a shallow buried trench system. According to this provision, the effluent applied to a shallow buried trench system must not exceed the maximum concentrations given in column three of Table 8.6.2.2.A, which identifies the thresholds for the tertiary level effluent. The treatment units listed in the Supplementary Guidelines to the 1997 OBC, including the Whitewater system, are also deemed to comply with the requirements of column three of Table 8.6.2.2.A (Sentence 8.6.2.2.(5)).

Table 8.6.2.2.A.

Other Treatment Unit Effluent Quality Criteria

Forming Part of Sentence 8.6.2.2.(1), (2) and (5)

Parameter

Secondary Effluent1

Tertiary Effluent1

BOD5

40

15

CBOD5

30

10

Suspended Solids

30

10

Column 1

2

3

Note to Table 8.6.2.2.A.:
1. Maximum concentration based on 30 day averages in milligrams per litre (mg/L)

Designers/installers may either use a treatment unit that is listed and described in the Supplementary Guidelines, or a treatment unit that complies with Table 8.6.2.2.A. Where a treatment unit is selected from the Supplementary Guidelines to the 1997 OBC, the unit shall follow all the requirements specified for that unit. Otherwise, the installation shall be according to the requirements of Part 8.

As described in the Supplementary Guidelines to the 1997 Ontario Building Code, when installing a Whitewater treatment unit in soils between 50 to 125 min/cm, a single pass free access sand filter must also be installed. However, for the proposed system it appears that the Applicant is not intending to install such a sand filter according to the Supplementary Guidelines. Instead, he is proposing that the free access sand filter be replaced with a layer of sand fill placed beneath the trench system.

Another issue raised during the hearing was the requirement for a mantle as per Clause 8.7.4.2.(1)(a) that concerns the leaching bed fill proposed by the Applicant in lieu of the free access sand filter. According to this clause, if the absorption trenches of a leaching bed are constructed in leaching bed fill with a percolation time identified under Clause 8.7.2.1.(1)(b), this fill (in this case, the 150 mm sand fill with a percolation time of less than 10 minutes proposed to be placed under the shallow buried trench system) must extend at least 15 meters beyond the outer distribution pipes in direction that provides horizontal movement of the effluent entering the soil. The mantle proposed by the Applicant, extends only four meters beyond the distribution pipes.

Therefore, at issue is whether the proposed elimination of a free access sand filter and the addition of 150 mm sand fill under the shallow buried trench system would affect the sufficiency of the system in complying with the relevant provisions of the OBC.

4. Provisions of the Ontario Building Code

Sentence 8.6.2.2.(2) Other Treatment Units

  1. A treatment unit that is used in conjunction with a leaching bed constructed as shallow buried trenches shall be designed such that the effluent does not exceed the maximum concentrations stipulated in Column 3 of Table 8.6.2.2.A.

Clause 8.7.4.2. Construction Requirements

  1. A leaching bed comprised of absorption trenches may be constructed in leaching bed fill provided that the unsaturated soil or leaching bed fill complying with Clause 8.7.2.1.(1)(b) extends
    1. ,
    2. for at least 15 m beyond the outer distribution pipes in any direction in which the effluent entering the soil will move horizontally.

Clause 8.7.2.1. General Requirements

  1. A leaching bed shall not be located:
    1. ,
    2. in soil or leaching bed fill having a percolation time

i. less than one minute, or greater than 125 minutes if constructed as a shallow buried trench, or

ii. less than one minute, or greater than 50 minutes for all other leaching beds.

5. Applicant's Position

The Agent for the Applicant submitted that the elimination of the free access sand filter is compensated for by placing the chamber system on a layer of sand fill with a percolation time of less than 10 min/cm.

The Agent started his argument by addressing the issues raised in the Technical Background Information (TBI) report prepared by the Housing Development and Buildings Branch of the Ministry. With respect to Sentence 8.7.4.1.(1) and Table 8.7.4.1.A. (loading requirements), the Applicant argued that the loading rate of the proposed system is 2.49 L/m2/day, which is less than the loading rate of 4.0 L/m2/day permitted by the OBC for soils with a percolation time of more than 50 min/cm.

The Agent continued that the low loading rate would compensate for the mantle size, which is proposed to extend only four metres beyond the outer distribution pipes instead of the 15 metre requirement under the OBC. With a loading rate less than the maximum specified by the OBC, there should be no lateral flow that requires a full mantle, he argued. However, comments made regarding the requirement for a minimum sand fill of 250 millimetres (Clause 8.7.4.2.(1)(a)) resulted in the Agent volunteering to increase the sand fill to 250 millimetres.

The Agent also considered that with a low loading rate and partial evapotranspiration of the effluent before reaching to the subsoil, the formation of biomat and resultant clogging of the pores of the native soil is unlikely. The Agent suggested that he had reached an agreement with the County regarding the size of the mantle.

The Agent argued that the system generally used in the County of Lambton is a conventional filter bed system. This system utilizes filter media sand in the bed to treat the effluent to the secondary level. As a result, the effluent that is applied to the top of the contact area sand for the final disposal has a secondary quality. According to the proposed design, however, a tertiary level effluent will be applied to the same sand fill prior to final discharge to the environment, he emphasized.

To support his assertion, the Agent submitted lab results from the same type of system installed in Windsor that demonstrates the effluent quality. This installed system has neither a septic tank proceeding the Whitewater unit nor a free access sand filter following it. However, from the lab results, it provides a tertiary level effluent, he argued.

The Agent then argued that the MOE classification of a Whitewater unit allowed the elimination of the free access filter sand, if the percolation time of the native soil is less than 50 minutes. The 150 mm sand fill (subsequently proposed to be 250 mm) proposed to be located under the shallow buried trench system will have a percolation time of less than 50 minutes and it was argued that the sand filter was no longer required.

The Agent concluded that instead of cutting a shallow buried trench system into the native subsoil, he is proposing to bury it in shallow sand fill and he offers this as a compensating measure for the free access sand filter.

6. Respondent's Position

The Respondent submitted that the OBC's recognition of "Whitewater" treatment systems and its description in the Supplementary Guidelines only concerns the treatment component of the sewage system and that the sewage system itself must comply with the related provisions of the Ontario Building Code.

The Respondent argued that the requirement for a free access sand filter in treatment systems such as Whitewater systems is to "provide a sufficient level of treatment to ensure proper disposal in heavier soils". There is no evidence to show that the proposed sand under the chamber is equivalent to the required free access sand filter and that it can provide the same level of treatment equivalent to the approved design. Thus, it is the County's position that the proposed sand fill as a compensating measure for the free access sand filter cannot be deemed acceptable.

The Respondent continued that the "construction of the absorption trenches including the shallow buried trench system does not refer to a reduction of the construction requirement itself". So it is the County's opinion that the chamber system should comply with the OBC requirements for shallow buried trench systems. The Respondent indicated that they had not initially been concerned about the absence of the mantle, however, during the hearing the issue of the mantle became more important.

In summation, the Respondent stated that the installation of Whitewater treatment unit is acceptable if it is installed in conjunction with the required free access sand filter, as described in the Supplementary Guidelines to the 1997 OBC.

7. Commission Ruling

It is the decision of the Building Code Commission that the proposed Whitewater treatment system discharging to a shallow buried trench on a 150 mm sand fill layer, without the provision of a free access sand filter and without a full mantle fails to provide sufficiency of compliance with Clause 8.7.4.2.(1) (b). The 15 metre mantle must be supplied and the sand fill must be at least 250 mm thick.

The Commission agrees that the Whitewater system likely meets the requirements of Sentence 8.6.2.2.(2) because it has been included within the Supplementary Guidelines and a free access sand filter may not be required by Sentence 8.6.2.2.(2). However, no information was provided relative to Clause 8.9.2.2 (1)(b) that the manufacturer does not require the free access sand filter where the percolation time of the native soil is between 50 and 125 minutes per centimetre

8. Reason/s

  1. A 250 mm sand mantle is required by Clause 8.7.4.2 (1)(b) of the OBC. The low loading rate does not negate the need for a mantle as the loading rate not only could be exceeded during peak uses, but it also may be augmented by precipitation, both resulting in effluent moving laterally.
  2. The Commission is not satisfied that a 150 or 250 mm thick layer sand fill is sufficient to "mask" the percolation time of the native soil, and as such it can not compensate for the high percolation rate of the native soil and elimination of the free access sand filter.
  3. Based on the fact that the "Whitewater" system is a listed treatment unit under the OBC (SG-5), it can be assumed that the equipment meets the requirements of Table 8.6.2.2.A. If the equipment meets these requirements, under Sentence 8.6.2.2.(2), there is no requirement for a free access sand filter.
  4. The equipment must be installed and operated in accordance with the requirements of the manufacturer (Clause 8.9.2.2.(1)(b)). Since the understanding in the past has been for the requirement for the free access sand filter, the manufacturer has placed this requirement in their design. Therefore, the free access sand filter is required, unless the manufacturer is prepared to make submissions under 8.6.2.2.(2).

Dated at Toronto this 13th, day in the month of July in the year 2000 for application number 2000-38.



_______________________________________________

Mr. Bryan Whitehead, Vice Chair





_______________________________________________

Mr. Frank Wright





_______________________________________________

Mr. Bill Fellner