1409 MADRONA AVE 2017-06-20 - Laserfiche WebLink

City of Everett May 3, 2010 Page 2 the northwest. The staircase will protect the slope from erosion by providing a safer route for the property owner to access the lower portion of his property. This would result in fewer disturbances to the slope, and lessen the potential for erosion. The critical slope will be more stable after the staircase is constructed. The foundations to support the staircase would likely consist of sono-tubes filled with structural concrete. The staircase configuration and foundation supports would be reviewed by a geotechnical engineer. These foundations would also provide stability to the slope. b. The trail surface meets all other requirements including all applicable water quality standards. Use of pervious surfaces is encouraged The construction of the staircase would allow rainwater to fall between the staircase slats and infiltrate into the hillside. A staircase is not a pollution generating surface; therefore no water quality treatment is necessary. The Hillside Restoration Plan previously submitted to the City, calls for a mix of deep rooting tress, shrubs and forbs to stabilize the slope and improve water quality. c. Critical area and buffer widths shall be increased where possible, equal to the width of the trail corridor, including disturbed areas. The construction of the staircase would be approximately four feet wide and 60 feet long. The staircase would have a smaller footprint and fewer impacts than the construction of a trail because the staircase will be elevated and include approximately 8 support footings. The support footings would be the only impact to the critical area as the staircase itself would be elevated. There is no way to increase the buffer width because of the elevated profile. Ten additional trees of the same species and sizes as listed in the Slope Restoration Plan will be placed at the base of the slope in areas that will be cleared for stabilizing the walls. The action of planting these trees will be deferred until, and if, the construction of the staircase has been permitted at the base of the slope to prevent conflicts. The trees will be field sited, with spacing of at least 10 feet between them. d Trails proposed to be located in landslide or erosion hazard areas shall be constructed in a manner that does not increase the risk of landslide or erosion and in accordance with an approved geotechnical report. The construction of the staircase will reduce the risk of landslide and erosion hazards by providing a safe access route down the hillside. The supports will likely consist of sono- tubes filled with structural concrete. The staircase configuration and foundation supports would be reviewed and designed by a structural engineer. The Hillside Restoration Plan calls for the planting of native, deep rooting vegetation which will also contribute to the long- term stability of the slope F:\J-miscUHON\Appl&SEPA\Building&Grading Permit Submittal000324_19 37 060134Path Narrative.doc