Laserfiche WebLink
/•“ftnip*' <br />r <br />I r,' <br />i/' <br />#2596 Brenshell Homes <br />E AW Need Determination <br />December 6,2000 <br />Page 5 <br />A majority of the runoff from the site (and from the roads to be constructed within <br />the Garden Lane corridor and within the site) will be directed to a stormwater pond <br />above the northerly ravine. This pond will serve both water quantity and quality <br />functions, and will result in flow rates in this ravine that are no greater than the pre­ <br />development condition. Reasons for directing a majority of the flows to this ravine <br />include that it has a flatter gradient with less erosion potential, and adding flows to <br />this ravine will have minimal impact to properties downstream as compared to the <br />potential impact if all flows were directed to the southeasterly ravine per the e.xisting <br />natural drainage areas. Further, this ravine discharges to a wetland hydraulically <br />separated from Lake Minnetonka by a driveway and culvert, hence Rirther treatment <br />of runoff will naturally occur within this wetland. <br />Both stormwater ponds are designed to meet National Urban Runoff Program <br />(NURP) standards for water quality. NURP ponds are designed to result in an <br />average reduction of phosphorus of 60%. Additionally, covenants will be established <br />requiring the property owners within the plat to use phosphorus-free fertilizers for <br />lawn maintenance. The water discharged from these ponds is not likely to be a <br />significant source of added pollution to Forest Lake Bay. <br />Road and utility construction and site grading will be occurring primarily in areas <br />where existing slopes are relatively level. The site plan has been revised a number <br />of times to incorporate changes suggested by the City staff and by the area residents, <br />resulting in decreased road lengths, minimization of disturbance of sensitive slopes, <br />and retention of existing vegetation within the ravine areas and on most of the slopes <br />exceeding 12%. <br />g)It is again noted that the property does not meet the criteria for being considered as <br />a bluff area under the Shoreland regulations, and is not subject to bluff impact zone <br />limitations. <br />Virtually all previous development in the Saga Hill area was completed prior to the adoption of <br />development requirements for managing stormwater runoff. As a result, there has been a need to <br />retrofit stormwater management facilities into the neighborhood. An example is the storm pond <br />constructed just west of the south end of Tonkaview Lane; another example is the sediment and rate <br />control berm required of the recently constructed home at 4685 Tonkaview. Additi mally, the draft <br />Oroiio Surface Water Management Plan indicates the need for new water quality ponds to protect <br />the quality of Forest Lake. The ponds proposed with this development will reduce the magnitude <br />and property impacts of those future ponds by trapping pollutants and retaining runoff higher in the <br />watershed.