Resolution 3572 - Laserfiche WebLink

alluvium or fill is thin enough to allow foundations to be placed on structurally sound soils, the liquefaction hazard is minimal. Erosion Hazards Certain types of soils are more prone to erosion than others. As with landslides, erosion is more likely to occur on steep slopes, especially in erosion prone soils types, soils that have been disturbed by human activities, and in the presence of rainfall and storm runoff. The most critical factor for control of erosion is construction management practices which limit clearing, require mitigative controls on development activity, limitation of soil disturbance to dry seasons of the year, re-vegetation, and maintenance of developed sites to prevent erosion after development. Groundwater Aquifers Groundwater aquifers are a porous geological formation which hold surface water that has percolated into the soil. Aquifers in Everett are not used as a drinking water source but are important for the moderation of stream flows. As water infiltrates permeable soils it is held during peak storm periods and is slowly released to moderate the flows that would be carried in a stream if no aquifer were present. Urban development reduces the natural infiltration capacity of the soil by covering the earth with impermeable surfaces, compacting soils which are not covered, removing vegetation, and increasing storm water runoff. In some cases, it may be desirable and practical to encourage infiltration of runoff from developed sites to recharge the aquifer. In other instances where the development is near steep slopes or on soils prone to landslides, it would not be advisable to recharge the aquifer, as saturation of such soils would increase the landslide hazard. Groundwater infiltration is more feasible in single family developments than in other types of developments in which there is a higher percentage of impervious surfaces. Although there are certain soils constraints or geological limitations which can be overcome through careful engineering practices, not all of the hazards associated with development of steep slopes, landslide or seismic hazard areas, or unstable soils can be solved through engineering solutions. Certain areas of the City simply are not suited for development. While it is not the City's intent to deny reasonable use of property, it must be recognized that not all properties can be developed to the full potential of the land use zone in which they are located. The burden to establish adequate long term safety measures must be on the property owner and not the City. B. Goal. 1. Protect the public health, safety and welfare by regulating development of the geologic and soils formations in the City which pose potentially hazardous conditions. 4