1600 121ST ST SE 2016-01-01 MF Import

pLAN REVIEW COMMENTB veaetated ewalea: A cross section showing the relationship of the swale, rockery, building three, and the wetland buffer should be ehown. A minimum of 4 horizontal feet must be shown for the rockery, both on plan views and cross-sections. Where a swale is located adjacent to a building, a minimum of ten feet of essentially flat ground must be provided between the building and the top of the swale. This diatance must also be shown clearly on the plan view an3 the cross-sectional detail. The entire associated side slope of the swale, from the bottom of the swale to the top of the adjar.ent bank, must have a maximum slope of 3:1 unless rockeries or retaining walls are used. The City is concerned about designing situations with water either flowing or standing near the base of rockeries and retaining walls. A sheet is attached that gives specifications for sit�ations where rockeries and/or r�taininq walls are adjacent to surface ponds or vegetated swales. The appropriate detail should be qiven on the plana. The maximum design depth of flow in the swale should be shown on the swale cross-sectional detail. The portion of the swale passing through the creek bnffer must be protected against erosion due to its steep longitudinal slope. The swale co�ld be lined with rip-rap through this sectfon since this section is _iot counting towards the required length of swale. The proposed qradinq in the swale area needs to be made more clear. Right no�a existing and proposed contour linea, fence location, buffer location, set-back lines, bottom of swale lines, etc., make it difficult Lo check the swale grading. A detail of this area at a scale of 1" = 10' or 20', showing only the exist•ing and proposed contours of the swale, should be provided. Due to the high grouridwater table in the area and the generally shaded conditions, the swale shou]-1 be designed as a biofiltration swale. Spot elevations in the bottom of the swale should be given at the head of the swale, at the sw�le outlet, and at approximatiely 5o foot intervalc along the length of the swal.c.