10/8/ W01. Daniel Catiglione First Gulf Corporation 3751 Victoria Park Avenue Toronto, ON M1W 3Z4

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1 10/8/2014 Daniel Catiglione First Gulf Corporation 3751 Victoria Park Avenue Toronto, ON M1W 3Z4 Dear Sir, Subject: Lower Morrison Creek Meander Belt Width Assessment MMM was retained by First Gulf Corporation to determine the meander belt width of the Lower Morrison Creek adjacent to the property at 514 South Service Road, in the Town of Oakville. The proposed development works at 514 South Service Road includes a proposed 4-storey Office Building and a proposed parking lot. The study area is shown in Figure 1. The study area is located adjacent to the Lower Morrison Creek, which is under the jurisdiction of Conservation Halton (CH). Therefore, the meander belt allowance or setback limits needs to be determined to ensure that the proposed developments are outside those limits. Scope of Work The scope of work involves: 1. Meander Belt Determination for the watercourse adjacent to the project site using an analytical method recommended by TRCA s Belt Width Delineation Procedures to estimate the tributary s meander belt. Meander Belt Allowance The meander belt allowance is used when planning authorities are considering development along unconfined rivers or streams. The meander belt allowance is the maximum extent that a watercourse migrates. When development or other activities are contemplated near a watercourse, it is desirable to designate a corridor that is intended to contain all of the natural meander and migration tendencies of the channel. Outside of this corridor, it is assumed that private properties and structures will be safe from the erosion potential of the watercourse. The meander belt can be determined using the following approaches: 1. Annable Approach: Annable has developed geomorphologic relationships of rural watercourses in Southern Ontario using 47 river data consisting of stream types B, C, E, 1 of 3

2 514 South Service Road 10/8/2014 and F. The type of watercourse in the study area could not be identified and the following empirical equation [Eqn. (1)] for meander belt width developed based on data from all stream types was used: 0.53 Wb =.2Q (1) 35 b In Eqn. (1), Qb = Bankfull discharge or peak flow with a return period of 1.5 yrs. This approach has been widely tested and applied for Ontario streams. 2. Parish Geomorphic Approach (2004): According to the Parish Geomorphic approach, the meander belt can be determined empirically from the drainage area and the stream power of the watercourse. The stream power can be determined from Eqn. (2) and the meander belt can be determined from Eqn. (3). SP = γqs (2) In Eqns. (1) and (2), SP = stream power (W/m 2 ) γ = specific weight of water (9806 kg/m 2 /s 2 ) Q = 2-yr flow s = channel gradient (m/m) Wb = meander belt width (m) DA = Drainage area (km 2 ) Wb = ln( SP DA) (3) It should be noted that the abovementioned procedures are only applicable for unconfined watercourses. In unconfined systems the watercourse is not confined within a visible valley and the flow of the water is free to shift across shallower lands. However, the Lower Morrison Creek adjacent to the project site cannot be considered as an unconfined watercourse. Therefore the abovementioned equations are inapplicable for the Lower Morrison Creek adjacent to the project site. Results and Discussion The meander belt width assessment equations for unconfined watercourses are inapplicable for the Lower Morrison Creek. The Lower Morrison Creek channel reach adjacent to the project site behaves more as a confined watercourse because of the significant development works enveloping both sides of the channel reach and restricting its probable migration tendencies. Therefore the channel reach is forced to follow a pre-defined path. Maintaining a buffer of approximately 7.5 m or utilizing the top of banks is in fact more applicable for the channel reach of Lower Morrison Creek adjacent to the project site. A project site plan dated January 31, 1978 (prepared by McConnell, Maughan Limited) shows the surveyed original flow path of the Lower Morrison Creek dating November 21, 1960 (attached at the end). The project site plan (January 31, 1978) shows that adjacent to the project site, the flow path of the Lower Morrison Creek has remained almost the same since The amount of migration from 1960 to 1978 ranges from 7-12 m. Furthermore, from 1978 to 2014 there has not been any noticeable channel migration. This indicates that the confined Lower Morrison Creek adjacent to the 2 of 3

3 514 South Service Road 10/8/2014 project site has gradually adopted a stable channel plan and profile. Conclusions and Recommendations The purpose of this work was to determine the meander belt width of the Lower Morrison Creek adjacent to the project site, in the Town of Oakville. The Lower Morrison Creek located west of the project site is a confined watercourse. Therefore, the analytical equations typically used in determining meander belt widths are not applicable in this case. Maintaining a buffer of 7.5 m on both sides (meander belt width of 15 m) or using the top of bank as the development limits would be more appropriate. Historical project site plan (McConnell, Maughan Limited January 31, 1978) also confirms a stable channel form with insignificant channel migration tendencies adjacent to the project site. If you need any additional information, please let us know. Sincerely, Yours truly, MMM GROUP LIMITED Asif Quader, P.Eng., Ph.D. Project Engineer Water Resources 3 of 3

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