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HomeMy WebLinkAboutOES 07-03 Ciú¡ o~ REPORT TO COUNCIL Report Number: OES 07-03 Date: February 12, 2003 From: Richard W. Holborn, P. Eng. Division Head, Municipal Property & Engineering Subject: Rear yard Drainage, Lots on Baylawn Drive and Primrose Court Recommendation: 1. That Report OES 07-03 regarding rear yard drainage on Baylawn Drive and Primrose Court be received; and 2. That copies of the report dated January 2003 prepared by Sernas Associates called "Baylawn Drive, Lots 1 to 4 Rear yard Drainage" be supplied to the affected lots; and 3. That the affected property owners be advised that the City of Pickering is prepared to coordinate and implement the recommended improvements at the City's cost in an attempt to reduce and mitigate the ongoing drainage concerns on private property. Executive Summary: Not Applicable Financial Implications: The cost to investigate, prepare a report on findings and provide recommendations was $4,000. This was funded by the Municipal Property & Engineering budget 2290-2392. Should the City decide to undertake the recommendations outlined in the report, it is estimated that the cost would be $15,000. This amount has not been included in any 2003 budget account. Background: City staff have been requested to investigate an ongoing rear yard drainage issue affecting approximately six (6) lots on Baylawn Drive and Primrose Court in the NW quadrant of Fairport Road and Finch Avenue. The lots were created through two separate plans of subdivision (40M-1554 and 40M- 1721) in the early 1990's and were assumed in 1994. The affected property owners requested another review of the drainage situation in June 2000 after a wet spring, and experiencing ongoing drainage problems. Report OES 07-03 Date: February 12, 2003 Subject: Rear yard Drainage, Lots on Baylawn Drive and Primrose Court Page 2 There is uniqueness to the design and planning of the subdivisions such that in order to create more usable backyards, the existing creek that traversed the rear property lines was engineered to be eliminated. The portion of the creek remaining (to the west of the affected lots), and the rear yards were engineered to drain into a large rear yard catch basin which is connected to the street storm sewer on Baylawn Drive. The problems that are being encountered consist of dead sod, wet, spongy conditions, swales not defined, catch basin inlets higher than the surrounding ground, and standing water. These issues were all confirmed during site visits by City staff. The City hired an engineering consulting firm Sernas and Associates, in October 2002 to coordinate a study of the soil, and groundwater in the area, in order to develop a recommendation and associated cost estimate. The soils and groundwater investigation determined that the underlying soil is too dense and impermeable, the surficial soil retains the surface water that is discharged to it, and the former creek in the rear yards of the affected lots may still be exhibiting its natural discharge (basil flow). . The recommendations acknowledge that the soil and groundwater conditions cannot be changed, but the drainage can be improved to relieve (not eliminate) the problems stated earlier. The recommendations consist of installing a series of sub-drains to collect and drain the surface and groundwater and to which the roof leaders can be connected. The sub- drains will be connected to the rear yard catch basins. A second stage of construction would consist of a series of interceptor swales. The estimated cost of all the works is $15,000 according to the report. In order for the improvements to be effective, all affected properties must cooperate, participate and allow access for construction. It must also be stated that the City's participation is going beyond standard practice, as work is being undertaken on private property to address private drainage issues with public funds. Should Council agree to undertake these works, it must be clearly acknowledged that this is a unique situation in that the original engineering design of the subdivision did not adequately address the ground water and soils conditions. The affected owners will be requested to sign off and acknowledge that the City has provided due diligence and best efforts to mitigate the problems, and that no further recourse is available. Report OES 07-03 Date: February 12, 2003 Subject: Rear yard Drainage, Lots on Baylawn Drive and Primrose Court Page 3 Attachments: Not Applicable Prepared By: ,,0. ~ ~/'/:t.Áa~?i>/:to),1 t~~o~. Richard W. ~olborn Division Head Municipal Property & Engineering RWH:ds Attachments Copy: Chief Administrative Officer Recommended for the consideration of Pickering City Council /" , .