Table 4-58 Critical Facility Exposure to Subsidence
| Jurisdiction | FEMA Lifeline | Critical Facility Type | Count |
|---|---|---|---|
| Arvada | Communications | Land Mobile Private Towers | 2 |
| Arvada | Communications | Microwave Service Towers | 2 |
| Arvada | Energy | Electric Substation | 2 |
| Arvada | Energy | Power Plant | 1 |
| Total | 7 | ||
| Golden | Communications | Land Mobile Private Towers | 4 |
| Golden | Communications | Microwave Service Towers | 5 |
| Golden | Food, Water, Shelter | Water Facility | 1 |
| Golden | Safety and Security | Government Facility | 2 |
| Golden | Safety and Security | School | 1 |
| Golden | Transportation | Bridge | 2 |
| Total | 15 | ||
| Unincorporated | Communications | Land Mobile Private Towers | 3 |
| Unincorporated | Hazardous Material | Tier II | 2 |
| Total | 5 |
Source: HIFLD and CERC
Future Development
Section titled “Future Development”As noted in the hazard profile section there are areas of western Arvada, Lakewood and unincorporated areas along the highway 93 and 470 corridors that are experiencing growth in and near potential subsidence hazard areas. Subsidence-resistant construction and mitigation efforts during construction are more cost effective than retroactive mitigation efforts and helps prevent damage from occurring. As such, vulnerability to this hazard is not anticipated to increase with new development, provided that land use planning and engineering regulations and practices are followed. Increased efforts to monitor mining operations, increased accuracy of mapping of former mining works, and emphasis on appropriate grading and ground compaction during development will help alleviate vulnerability for future development in unknown areas of risk. In many ways, the efforts of Jefferson County to pre-empt the subsidence hazard (along with the erosion and swelling soils hazards) is a best-practices example for successful mitigation efforts and projects.
Other development that could occur in or near potential subsidence areas include the proposed Northwest Parkway, a segment of a toll road that has been studied and planned for several years to connect E470 and C470 north of Golden and through western Arvada.
Overall Hazard Significance
Section titled “Overall Hazard Significance”Subsidence events in Jefferson County have had minimal impacts on the planning area, due in large part to careful land use planning. The geographic extent of the hazard is considered limited. The probability of future occurrences is considered occasional and the magnitude/severity for the event of record is limited. In addition, the HMPC considers the hazard to have a low overall impact on the jurisdiction. This equates to an overall impact rating of medium.
This rating is based on the current development policies in place in the County, which limit construction in vulnerable areas. If previously unknown areas of subsidence are discovered, particularly in already- developed areas, this assessment may change. In addition, as development continues out and below the areas of mines worked in steep-slope conditions, those properties may experience a higher vulnerability to landslides caused by subsidence in those areas. This information is also addressed in the landslides profile and can be avoided with continued good mitigation practices.