16.50.410 Classification of Geologically Hazardous Areas.
The level of risk for each geologic hazard type is described in this Section. Documentation of specific areas in which a known or suspected risk exists for each of the following hazard areas is provided in the pertinent city critical area map. The provisions of this title apply only to those areas for which a known or suspected risk exists, as identified in Table 16.50.5 below.
Classification | Documentation and Data Sources |
|---|---|
Known or Suspected Risk | Documentation or projection of the hazard by a qualified professional exists. |
Low or No Risk | Documentation exists by a qualified professional regarding low hazard risk or lack of hazard. |
Risk Unknown | Documentation, data, or projection of the hazard risk by a qualified professional are not available or sufficient to determine the presence or absence of a geologic hazard. |
(1) Erosion Hazard Areas – Known or Suspected Risk. The Thatuna Soil Series within the city is identified as having a potentially severe erosion hazard, as identified in Table 16.50.6 below. The Thatuna Series within the city consists of: the Thatuna Silt Loams on slopes of 7 to 25 percent and 25 to 40 percent and the Thatuna-Tilma Silt Loams on slopes of 7 to 25 percent.
Thatuna Soil Series Erosion Hazard Potential | ||
|---|---|---|
Soil Series Name | Slope (%) | Erosion Hazard |
Thatuna Silt Loam | 7 – 25 | Moderate to Severe |
Thatuna Silt Loam | 25 – 40 | High to Severe |
Thatuna-Tilma Silt Loams | 7 – 25 | Moderate to Severe |
(2) Landslide Hazard Areas – Known or Suspected Risk. Areas of severe limitations to building development as identified by the USDA-NRCS for reasons other than slope for one or more types of building development include the soil series in Table 16.50.7 below.
Soil Name | Risk Level: Reason | ||
|---|---|---|---|
Dwellings w/o Basements: | Dwellings w/ Basements | Small Commercial Buildings | |
Caldwell | Severe: floods | Severe: floods, wetness | Severe: floods |
Garfield | Severe: shrink-swell, low strength | Severe: shrink-swell, low strength | Severe: shrink-swell, low strength |
Gwin-Tucannon | Severe: slope | Severe: depth to rock, slope | Severe: slope |
Konert | Severe: floods, wetness, shrink-swell | Severe: floods, wetness, shrink-swell | Severe: floods, wetness, shrink-swell |
Latah | Severe: floods, wetness, shrink-swell | Severe: floods, wetness, shrink-swell | Severe: floods, wetness, shrink-swell |
Naff | Severe: slope, shrink-swell | Severe: slope, shrink-swell | Severe: slope, shrink-swell |
Thatuna-Tilma | Severe: shrink-swell, slope, wetness | Severe: wetness, shrink-swell, slope | Severe: shrink-swell, wetness, slope |
Tucannon | Severe: slope | Severe: depth to rock, slope | Severe: slope |
(3) Seismic Hazard Areas – Low or No Risk. There are no known specific faults that are likely to create a significant seismic hazard within the city.
(4) Mine Hazard Areas – Known or Suspected Risk. No subsurface mines exist in the city. Open mines such as basalt rock pits and sand/gravel pits that exist within the city are mine hazard areas.
(5) Volcanic Hazard Areas – Low or No Risk. Pullman is not located within a volcanic hazard zone. If a volcanic eruption were to occur in the western part of Washington, the only anticipated impact in Pullman would be ash deposition.
(6) Other Hazard Areas. Other geologically hazardous areas may be designated by the Director of Community Development if documentation thereof is available. (Ord. 21-15 §6, 2021; Ord. 19-6 §24, 2019; Ord. 07-27 §6, 2007; Ord. 03-18 §42, 2003).