SCHEDULE B SUPPLEMENTARY DESIGN GUIDELINES

SUPPLEMENTARY DESIGN GUIDELINES

SUPPLEMENTARY DESIGN GUIDELINE GENERAL USE DESCRIPTION

This schedule contains supplementary design guidelines to be applied in conjunction with the MMCD, which shall apply to all Works and Services constructed within the Town of View Royal.

Supplementary Design Guidelines contained within this Schedule supplement or supersede the MMCD. Where the Town of View Royal Supplementary Design Guidelines are in conflict with the MMCD, the Town of View Royal Design Guidelines shall take precedence.

Section number and clause numbers in the Town of View Royal Supplementary Design Guidelines coincide with the MMCD numbering protocol.

Table of Contents

Section 3.0 – Sanitary Sewers

Off-site sanitary Works and Services shall be designed and in conformance with the MMCD.

Section 4.0 – Storm Drainage

4.3.2 – Stormwater Design Criteria

Replace the portion of Section 4.3.2.1 specifically describing the Minor System and Major System, with the following:

Minor System – Consists of pipe, gutters, catch basins, driveway and local road culverts, local roadside ditches and open channels, to be designed to contain flows up to a 10-year return period to minimize inconvenience of frequent surface runoffs.

All minor system components are to be sized to ensure that the hydraulic grade line of 10-year frequency flows remain below ground surface, and the flood protection elevation of dwellings, or within bank limits in the case of open channels and bio-swales.

Major System – Consists of surface flood paths, roadways, trunk storm sewers and culvert crossings under collect roads, arterial roads and provincial highways, watercourses, and bypass structures for onsite and offsite stormwater management facilities, to be designed to safely convey design flows up to a 1:100-year return period, as directed by the Town, to minimize damage to life and property.

4.3.4 Climate Change Impact Considerations

Add to the end of this section the following:

The Engineer of Record shall disclose and describe the climate change approach used in the design of the storm drainage infrastructure. The “do nothing approach” is not accepted for permanent infrastructure.

4.7 – Runoff Analysis Method

Replace this section with the following:

Rainwater management design should be carried out using one or more of the following methods as indicated below. Disclosure of methodology used and calculations must be submitted with designs. The Rainfall Intensity Duration curve is provided for reference in the figure below.

• Rational Method: Applicable in most cases for the purposes of conveyance design only and for areas less than 10 hectares in size. The rational method must not be used for designing retention or detention structures in any case, including but not limited to the development of flow rates, infiltration rates, and routed storage volumes.
• Hydrograph Method: Applicable for complex systems involving multiple catchments with highly variable land use conditions, where flow attenuation features are involved (e.g. detention pond, constructed wetland), or for gross areas exceeding 10 hectares. Computer models shall be SWMM based, or as otherwise approved by the Town of View Royal.
• Mass Balance: Volumetric based computations may be used to supplement flow analysis for the design of water quality treatment facilities and Best Management Practices intended for rainwater retention.

Note: Aside from the runoff analysis method applied, hydraulic grade lines and associated system performance shall consider governing downstream hydraulic boundary conditions, which may be available from the Town of View Royal. If not available from the Town, or available to the degree necessary to support the design, additional off-site analysis may be required.