Laserfiche WebLink
City of Orono <br />Surface Water Management Plan February 2019 44 <br />limestone weirs will assist with dissolved phosphorus removal and reduce erosion by <br />slowing runoff flow through the ravine, and planting of native vegetation will stabilize <br />slopes, reduce erosion, and assist in phosphorus removal. <br />Prioritization:Medium <br />Estimated Cost: Unknown <br />Project Partner(s): MCWD <br />Funding Source(s): City, MCWD, Grant funding <br />Timeframe: Unknown <br />N-2. Tonkawa Road Ravine Stabilization <br />Collaborate with MCWD to stabilize an existing ravine (approximately 400’) in the <br />neighborhood of 420 Tonkawa Road that has eroded to a depth of several feet. Due to <br />excessive sediment and organic material loads from erosion, North Arm Bay of Lake <br />Minnetonka is being prematurely filled in and additional load is being transported <br />downstream. This contributes to increased sediment and phosphorus loads and reduced <br />dissolved oxygen in runoff, and is extremely detrimental to water quality. In order to <br />reduce detrimental impacts on downstream systems, this ravine needs to be stabilized. <br />To repair the ravine, the City will design a stable cross-section, install limestone grade <br />control weirs with plunge pools, and plant deep rooting native vegetation. Placement of <br />boulder toe protection will stabilize side slopes and reduce erosion, installation of <br />limestone weirs will assist with dissolved phosphorus removal and reduce erosion by <br />slowing runoff flow through the ravine, and planting of native vegetation will stabilize <br />slopes, reduce erosion, and assist in phosphorus removal. <br />Prioritization:Medium <br />Estimated Cost: Unknown <br />Project Partner(s): MCWD <br />Funding Source(s): City, MCWD, Grant funding <br />Timeframe: Unknown <br />N-3. Farview Lane Ravine Stabilization <br />Runoff draining from Stormwater Pond 4-3, located in the northeast corner of the <br />intersection of Farview Lane and Fox Street, currently flows through a 15” culvert <br />under Fox Street, then through a section of ravine before flowing through an 18” <br />culvert under Farview Lane, and then through a final section of ravine before outletting <br />to Maxwell Bay of Lake Minnetonka. The culvert under Farview Lane is in extremely <br />poor condition, and the road slope is beginning to undercut due to culvert failure on the <br />upstream end. In addition, the ravine has eroded to a depth of a few feet, resulting in <br />the transport of eroded sediments. Due to excessive sediment and organic material <br />loads from erosion, Maxwell Bay of Lake Minnetonka is being prematurely filled in <br />and additional load is being transported downstream. This contributes to increased <br />sediment and phosphorus loads and reduced dissolved oxygen in runoff, and is <br />extremely detrimental to water quality. In order to reduce detrimental impacts on <br />downstream systems, this ravine needs to be stabilized. To repair the ravine, the City <br />will design a stable cross-section, install limestone grade control weirs with plunge <br />pools, and plant deep rooting native vegetation. Placement of boulder toe protection <br />will stabilize side slopes and reduce erosion, installation of limestone weirs will assist <br />with dissolved phosphorus removal and reduce erosion by slowing runoff flow through <br />the ravine, and planting of native vegetation will stabilize slopes, reduce erosion, and <br />assist in phosphorus removal. Also, due to imminent failure of the road crossing, storm <br />sewer improvements should be considered for this area. As such, this project should be <br />coordinated with Section 5.4. <br />Prioritization:Medium