02-16-2016 Planning Commission Packet

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I � to the provide accessibility for the property west ot�the development site. A sidewalk is proposed on 1 side of a11 roadways with residential front yards. The sidewallc will be extended through the site to Wayzata Boulevard right of way northeasterly to the signalized Wayzata Boulevazd / Old Crystal Bay Road intersection and crosswalks. The intemai street corridors are proposed with a 50 foot wide right of way, a 30 feet wide road measured at back of curb,and a 5 foot sidewalk on 1 side of the roadway. Gradin� The flat existing grade, wetland overflow elevation, and high table require that the proposed grading plan raise the site in the areas of the proposed home sites. The geotechnical report has identified the water table at 1018.7, the lowest home floor proposed in the grading p1an is 1Q23.5 or 4.8 feet above the estimated water ta.ble. The onsite wetland cornplex has an above ground o�erflow elevation of 1022 and so the homes backing up to the wetland have been designed with a lowest opening walkout elevation of 1024 or higher. To reduce and limit the amount of earthwork barrow, the site has been designed to raise Iots only to at or very close to the limiting elevations. The resulting grading plan is a design that has very little change in home elevations generally in the 1 Q32 range for garage floors and 1423.5 and up for the Iowest floors. At this time an earthwork estiunate has not been completed but the site will likely require borrow to estia.blish the necessary home elevations. Sanitary Sewer and W�atermain The site has access to public sanitary sewer and waterma.in via trunk utilities in the intersectzon of Wayzata Bouleva.rd West and Old Crystal Bay Road. The plans propose to connect to an existing sanitary manhole in the southeast corner of the intersection. The connection is proposed by a direction bore to the rnanhole with a proposed inside drop using an IntraFlow-- Inside Drop System by Royal. The boring will only extend from the existing manhole to a point beyond the existing signal system that will allow far open excavation without disturbance to the signal. The inside drop design option will reduce the size of the existing road disturbance. The sewer will be extended throughout the development with two stubs proposed to the groperty to the west of the site. The site proposes to connect to the existing watermain located along the west side of Old Crystal Bay Roaci and south side of Wayzata Blvd within public right of way. The water main will be extended to the west similar to the sewer system and at this time no secondary connection is proposed due to iack of avaiiability of an additional watermain connection point. Stormwater Management The development is located within the '_Vlinnehal�a Creek Watershed Dist�rict and is subject to their review along with the City. The proposed development is rec�uired to meet stormwater management requirements for volume control, water q�ality, and peak rate cozztrol. The development plan provides a stormwater management systern including 1 filtration basin and 2 retention pands. Multiple existing conditions make the site not conducive for stormwater abstraction by infiltration. The szte soils are heavier clay with "D" chara.cteristics and the water t�ble is very close to the surface elevation not allowing the required 3' zn.inunum separation between inf�ltration in most areas, The filtration basin is designed ta receive direct roadway runoff, however, a pretreatment sump mazxhole and basin forebay axe proposed ta provide pretreatment of the roadway runoff. The filtration basin will have an PRD, Rezoning, and Preliminarv Plat Submittal Januarv 2Q, 2016 Orono Preserve Page 5 of 7