WHATCOM COUNTY J.E. “Sam” Ryan Planning & Development Services Director 5280 Northwest Drive Bellingham, WA 98226-9097 360-676-6907, TTY 800-833-6384 360-738-2525 Fax Memorandum TO: Planning Commission FROM: Cliff Strong, Senior Planner THROUGH: Mark Personius, Asst. Director DATE: 26 April 2016 SUBJECT: Revised Volcanic Hazard language for 28 April 2016 _________________________________________________________________________ Since we sent out your packet last week, in which we provided some potential lahar language based on your direction, Andy Wiser, staff geologist, has conferred with other geologists and has some proposed revisions. Also, we have additional information for you to consider in your deliberations. Revisions Andy has amended the draft code based on his discussions with other geolgists. This language is attached, and replaces that found in your packet. (Note: it is not in underline/strikeout mode, as there were too many changes.) He has also prepared a map (attached) that shows the proposed Lahar Inundation Hazard Areas, which may help you in analyzing the effects the proposed language might have. The approach consists of: • Defining 7 volcanic hazard areas, 3 of which are lahar inundation areas, which are then broken down into 4 lahar hazard zone types. These are based on the types of hazards most likely to occur in a particular area, as well as travel times. • Allowing most types of development allowed by the underlying zone, but limiting certain large occupancy and special uses to different degrees, depending on the hazard zone. • If a use will have an occupancy of greater than 25, requiring a volcanic hazards assessment, incluing a lahar travel-time analysis, recommendations for siting of improvements intending to avoid volcanic hazards, and a volcanic hazard management and evacuation plan. Emergency Management/Hazard Mitigation Plan As mentioned in the previous memo, the language of the proposed volcanic code is based on the Pierce County code, though modified for Whatcom County due to our own unique geology and the fact that we don’t have the same level of warning system and community-wide practiced response plans in place that they do. There, the communities in the lahar zones have sirens, media alerts, evacuation routes, etc., and schools, hospitals, and other large occupancy uses practice evacuations. Our preparedness and response plan is contained in the Whatcom County Natural Hazards Mitigation Plan (the volcanic hazard portion of which is attached), developed by a consortium of emergency responders under the management of the Whatcom County Division of Emergency Management, in the Sherriff’s office. Attached is the Volcanic Hazard section of that plan. As you’ll see, mitigation strategies (p 2-77 and 78) really only focus on educating people about what to do in case of a volcanic emergency. There’s also another plan, the Mount Baker-Glacier Peak Coordination Plan (attached), which is more specific in terms of preparedness and response to volcanic activity. It deals well with how all the agencies are to coordinate their efforts but again doesn’t really address how to get people out of the hazard areas once something is happening. Ultimately, it may be a good idea to recommend to Council that a more robust emergency plan and volcanic hazard public safety notification system be developed and put into place. CompPlan Policies As you know, regulations must be consistent with the Comprehensive Plan policies. In the draft CompPlan (currently undergoing County Council review), the following goal and policies are relavent. Goal 11F: Minimize potential loss of life, damage to property, the expenditure of public funds, and degradation of natural systems resulting from development in hazardous areas such as floodplains, landslide-prone areas, seismic hazards areas, volcanic impact areas, abandoned mine and exploratory gas well locations, potentially dangerous alluvial fans, and other known natural hazards by advocating the use of land acquisition, open space taxation, conservation easements, growth planning, regulations, and other options to discourage or minimize development, or prohibit inappropriate development in such areas. Policy 11F-4: Establish acceptable levels of public risk for development in known natural hazard areas based upon the nature of the natural hazard and levels of public risk, and maintain regulatory criteria for approving, disapproving, conditioning, or mitigating development activity. Policy 11F-6: Prohibit the siting of critical public facilities in known natural hazard areas unless the siting of the facility can be shown to have a public benefit that outweighs the risk of siting in the particular hazard area. Policy 11F-12: Consider conducting a public process with affected citizens, technical experts, and decision-makers to establish recommended levels of public risk for each of the identified natural hazards. In developing recommended levels of public risk for natural hazards, consider the appropriate variables affecting developments in hazardous areas. These variables may include: • Specific types of risk associated with the particular hazard area; • The gradation of hazards associated with a particular geo- hazard; • Level of detail necessary to map hazard areas; • Different levels of risk associated with different ownership classes (e.g. public ownership versus private ownership); • Different levels of risk associated with different types of land uses; and, • Mitigation measures related to specific adverse impacts of development in hazard areas. Once a set of risk levels have been identified, propose these risk levels for adoption by the County Council as the level to which future development must be designed. Policy 11F-13: Consider establishing acceptable levels of public risk for use in approving and conditioning development activity in known natural hazard areas. The established level of risk may be expressed as the potential hazard posed as determined by scientific and historical methods applicable to each specific natural hazard. Staff would point out that in the process the Planning Commission is using to recommend revisions to the volcanic hazard regulations, we are not “conducting a public process… to establish recommended levels of public risk” as contemplated in the above policies. Rather, we are recommending development regulations based on your discussion and on the best available science we currently have. As we’ve mentioned, we expect that within the next two years we will have much better information on potential lahar risk from updated USGS data and new LiDar imagery on which to reconsider volcanic hazard maps and associated event risks. This is why staff recommends these regulations should be considered as interim until more information is available and a more robust discussion is held with a wider stakeholder base (not just the BIAWC, but emergency managers and responders, property owners, residents, businesses, etc., as well). Potential Volcanic Hazard Area Regulations 16.16.310 Designation, mapping, and classification. C. Classification. For purposes of this chapter, geologically hazardous areas shall include all of the following: 4. Volcanic Hazard Areas. Volcanic hazard areas are those areas that have been affected, or have the potential to be affected, by Case M, Case I, or Case II lahars, or by debris flows or sediment- laden events originating from the volcano or its associated deposits. Also included as hazards are areas that have been, or have the potential to be, affected by pyroclastic flows, pyroclastic surges, lava flows, or ballistic projectiles, ash and tephra fall, volcanic gases, and volcanic landslides. In addition, volcanic hazards include secondary effects such as sedimentation and flooding due to the loss of flood conveyance as a result of river channel and flood plain aggradation. The implications of secondary effects may be observed at some distance from the initiating event, and may continue to impact affected drainages over many decades following the initiating event. Secondary effects may significantly alter existing stream and river channels, associated channel migration zones and flood plains due to stream and river bed aggradation and channel avulsion. Volcanic hazards include areas that have not been affected recently, but could be affected by future events. Volcanic hazard areas are classified into the following categories: a. Case M Lahar Inundation Hazard Areas. Areas that could be affected by cohesive lahars that originate as enormous avalanches of weak, chemically-altered rock from the volcano. Case M lahars can occur with or without eruptive activity. A single, post-glacial, Case M Lahar deposit is known to have traveled down the Middle Fork Nooksack River, and is postulated to have continued down the main stem of the Nooksack River, eventually reaching Bellingham Bay and to have also flowed north to Canada along the pre-historic path of the Nooksack River. Case M Lahars are thus interpreted to pose a threat to the Sumas River drainage due to the potential for bed aggradation and channel avulsion to overtop the low- lying drainage divide that exists between the Nooksack and Sumas River drainages. Case M Lahars are considered high consequence, low-probability events. b. Case I Lahar Inundation Hazard Areas. Areas that could be affected by relatively large non- cohesive lahars, which most commonly are caused by the melting of snow and glacier ice by magmatic activity and associated processes, but which can also have