968 St. Laurent Bulevard, Ottawa. Stormwater Management Report. Prepared for: Eric Haar Architect Inc.

Transcription

1 968 St. Laurent Bulevard, Ottawa Stormwater Management Report Prepared for: Eric Haar Architect Inc. March 2012

2 968 St. Laurent Blvd. Ottawa Storm Water Management Report Table of Contents 1. Introduction Existing Site Drainage Proposed development Proposed Water and Sanitary Services Conclusion... 4 Apendix A... 5 Apendix B... 9 ARCH-Nova Design Inc 2

3 968 St. Laurent Blvd. Ottawa Storm Water Management Report 1. Introduction The subject property is located at 958 St. Laurent Blvd., Ottawa. The proposed work comprises of an existing 2.5 storey small office building for medical facility occupancy. Two small additions are planned, which will increase the floor area for approximately 50%. Minimal site redevelopment is anticipated however overall drainage area and its permeability will remain the same. Municipal drainage and storm water services are provided on the site and on the St. Laurent Boulevard. The owner plans to demolish the three existing additions as shown on the plan. 2. Existing Site Drainage The subject property is 88% covered with impervious surfaces; the building and surrounding parking area. Small green area with three grown trees is in the front along the main street (St.Laurent Blvd). The site is drained through two catch basins located at two entrances of the property. 3. Proposed development The owner plans to construct additions (as shown on the plan) and demolish existing additions. No major work is planned for the surrounding parking. Proposed Stormwater Management remains identical to the existing with the same ratio between the impervious and pervious surfaces. ARCH-Nova Design Inc 3

4 968 St. Laurent Blvd. Ottawa Storm Water Management Report 4. Proposed Water and Sanitary Services Water and sanitary services will be evaluated upon a final architectural plans are provided. An Adequacy of Municipal Services Report will address these services. 5. Conclusion The property at 958 St. Laurent Blvd. will be redeveloped into a small medical services building. The ratio between pervious and impervious areas will remain the same and no additional stormwater facilities (ponding, catch basins and orifices) will be required (see Appendix A) The erosion and sediment control will be provided by the green areas in front of the building as it is now. Drainage around the foundation will be provided by weeping tiles connected to the storm water laterals and further to the storm water main pipe on St. Laurent Boulevard. Prepared by: Zoran Mrdja, P.Eng. Authorized by Professional Engineers of Ontario to provide professional services to public Ottawa, March ARCH-Nova Design Inc 4

5 968 St. Laurent Blvd. Ottawa Storm Water Management Report Apendix A Pre and Post Development Runoff ARCH-Nova Design Inc 5

6 Project Number: 968 St. Laurent Blvd. Ottawa PRE-DEVELOPMENT (Entire Area) The pre-development time of concentration is 20 minutes where: I 5 = / (Tc ) I 100 = / (Tc ) I 5 = 70.3 mm/hr I 100 = mm/hr Surface Type ID Area (ha) Percent of total Area C A X C (ha) Grassed Area % Asphalt/Concrete % % Q 5pre = (2.78)*(C)*(I 5 ) * (A) Q 5pre = 2.78 x 0.88 x 70.3 x 0.12 Q 5pre = 20.6 L/s TOTAL % Weighted C = 0.88 Q 100pre = (2.78)*(C)*(I 100 ) * (A) Q 100pre = 2.78 x 0.88 x x 0.12 Q 100pre = 35.2 L/s POST-DEVELOPMENT (Entire Area) The post-development time of concentration is 20 minutes where: I 5 = / (Tc ) I 100 = / (Tc ) I 5 = 70.3 mm/hr I 100 = mm/hr Surface Type ID Area (ha) Percent of total Area C A X C (ha) Grassed Area % Asphalt/Concrete % Q 5post = (2.78)*(C)*(I 5 ) * (A) Q 5post = 2.78 x 0.88 x 70.3 x 0.12 Q 5post = 20.6 L/s Q 100post = (2.78)*(C)*(I 100 ) * (A) Q 100post = 2.78 x 0.88 x x 0.12 Q 100post = 35.2 L/s TOTAL % Comment: Postdevelopment runoff does not Weighted C = 0.88 increase and current onsite storage has sufficient capacity.

7

8

9 968 St. Laurent Blvd. Ottawa Storm Water Management Report Apendix B Site Plan ARCH-Nova Design Inc 9

10