Agenda - Council - 09/22/2020 - Laserfiche WebLink

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CC Regular Session 5. 20. Meeting Date: 09/22/2020 By: Bruce Westby, Engineering/Public Works Information Title Adopt Resolution #20-215 Accepting Quotes and Awarding Contract for 9591 Inverness Lane Drainage Improvements, Improvement Project #20-08 Purpose/Background: Purpose: The purpose of this case is to adopt Resolution #20-215 accepting the quote of and awarding a construction contract to Dryden Excavating, Inc. for 9591 Inverness Lane Drainage Improvements, Improvement Project #20-08. Background: In December of 2015, the property owner at 9591 Inverness Lane first contacted Staff to discuss some drainage concerns regarding the operation of the drainage ditch east of Jarvis Street on both sides of Inverness Lane, which had just been improved that summer as part of the Jarvis Street Reconstruction project. After numerous conversations with Elk River Staff, who led this street reconstruction project, and with Staff from Bolton & Menk, who designed the project, prepared plans and specifications, and inspected construction, some grading modifications were made as part of the project punch list work. On June 12, 2016, the property owner at 9591 Inverness Lane reached out again to let us know the ditch appeared to be flowing well and that his concerns had been addressed. In early 2019, the property owner contacted Staff again to report that the swale traversing their back yard, which conveys stormwater runoff from several properties upstream, was full of water and was roughly 10 feet from the back of their house and encroaching under the rear edge of their deck. The property owner said the swale had never been this full of water before. That spring, Staff began working on plans to improve drainage in the ditch east of Jarvis Street, including collecting survey shots and investigating options for improving drainage in the ditch east of Jarvis Street to prevent water from backing up into the rear yard of this property. During late winter and early spring, snow and ice in the ditches and the culvert under Inverness Lane prevents stormwater runoff from flowing properly, causing stormwater to back up into the swale in the rear yard of 9591 Inverness Lane. Staff confirmed the ditch to the south of Inverness does not have proper slope for drainage. Staff originally looked at re -grading the ditch east of Jarvis Street to the existing pond one lot south of Inverness Lane. Due to existing private utilities, poles, impacts to existing mature trees, and to avoid steep ditch side slopes, Staff determined piping the runoff through this stretch to be the most feasible approach. This project proposes to remove the two existing bituminous flumes on either side of Inverness Lane, along with the 12-inch concrete culvert under Inverness Lane. Instead, 18-inch concrete storm sewer pipe will be placed between two 48-inch diameter concrete catch basins with 2-foot deep sumps in the bottom to capture sand and other debris that would otherwise end up in the bottom of the City's stormwater ponds, where it is more costly to remove. Then, 18-inch high -density polyethylene (HDPE) storm sewer pipe will be extended south within City right-of-way east of Jarvis Street to the south edge of the property immediately south of Inverness Lane. The HDPE pipe will then tie into the existing ditch that routes runoff to the east to the existing stormwater pond by the golf course. Fill will be placed over the storm sewer pipe, and a shallow swale will be graded above the pipe to direct runoff from the street and adjacent properties to the existing ditch and stormwater pond. The attached plans show the proposed improvements and have been shared with the property owner.