Geologic Hazards and Whatcom County Code. Andy Wiser, L.E.G , ext 50274

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1 Geologic Hazards and Whatcom County Code Andy Wiser, L.E.G , ext 50274

2 Chapter 16.16, Article 3 Geologically Hazardous Areas Purpose: 1. Minimize Risk: Minimize risks to public health and safety and reduce the risk of property damage by regulating development on or adjacent to geologically hazardous areas. 2. Avoid Future Flood Mitigation Measures: Regulate land use to avoid the need for flood control devices or channel modifications on alluvial fans and allow for natural hydrologic processes. 3. Environmental Preservation: Protect aquatic habitats, wetlands, and fish and wildlife by avoiding or minimizing impacts that can result from landslides and erosion. 4. Balance: Maintain natural geological processes while protecting existing and new development. 5. Establish review procedures.

3 CAO-GHA General Standards Avoid - Move development to non-gha / buffer if available under contiguous ownership. 2. Locate critical facilities outside GHA. 3. Subdivision located wholly within GHA is prohibited. 4. Engineer / construct allowed developments to minimize risk. 5. Professional assessment by qualified, licensed professional.

4 Regulated Geologic Hazards Seismic.340 Volcanic.350 Tsunami and Seiche.365 Alluvial Fan.345 Mine.370 Erosion.355,.360, Landslide.325,.330,.335 Each hazard criteria explicitly defined by

5 Presentation Outline Systematic Review of each GHA Code Review Application Screening Tools Best Available Science Short-comings Improvements

8 Seismic Hazards Seismic Hazard Areas. Development may be allowed in seismic hazard areas when design conforms to analysis and design criteria of the International Building Code (2) Seismic hazard areas shall include areas subject to a severe risk of earthquake damage as a result of seismically induced ground shaking, differential settlement, slope failure, settlement, lateral spreading, mass wasting, surface faulting or soil liquefaction.

9 NEHRP Site Class Map

10 NEHRP Liquefaction Susceptibility Map

11 Seismic Acceleration for the county showing the revised acceleration Incorporating the Boulder Creek Fault.

16.16.350 Volcanic Hazard Areas Development may be allowed ; provided, that all reasonable measures have been taken to minimize risks and other adverse effects, and when the amount and degree of the

12 Volcanic Hazard Areas Development may be allowed ; provided, that all reasonable measures have been taken to minimize risks and other adverse effects, and when the amount and degree of the alteration are limited to the minimum needed to accomplish the project purpose (4) - Volcanic hazard areas shall include areas subject to lava flows, pyroclastic flows, pyroclastic surges, mud flows, lahars, debris flows, debris avalanche, ash (tephra) clouds or ash (tephra) fall, lateral blast, ballistic debris, or flooding resulting from volcanic activity. Copyright , John H. Scurlock

13 Screening Tools Gardner and others, 1995, Potential Hazards From Future Activity of Mount Baker Washington Case year recurrence interval Case year recurrence interval Case M - One event (~6,800 years ago) in past 14K

14 For lahar inundation zones the following shall be allowed A. Development that meets reasonable use standards B. Sewer collection below ground, no impact due flooding D. Accessory structures not involving human occupancy shall be allowed E. Single-family developments and duplexes may be permitted in lahar hazard areas subject to WCC (A). (Ord ) C. Critical facilities, as defined in subsection 1 of critical facilities, Article 8 of this chapter, of 50 or more persons may be permitted within lahar inundation zones subject to the conditional use permit requirements of Chapter WCC; provided, that the following criteria are also met: 1. The applicant demonstrates the amount of time that is anticipated for a lahar to reach the proposed project and evacuation route, together with a description of existing or proposed detection and notification systems to be installed and maintained by a public entity 2. The applicant has provided an emergency evacuation plan is located directly adjacent to a safety zone that is within walking distance in an amount of time less than the anticipated time after the triggering of an alarm Short-comings: Little is done to address SFR development, although no subdivision. As a result many homes have likely been constructed that may be subject to lahar inundation.

15 Tsunami & Seiche Hazards Tsunami and Seiche Hazard Areas Code directs T.A. to Volcanic Hazard Areas

16 DNR Evacuation Routes Sandy Point Bellingham Birch Bay & Blaine Lummi Island Lummi Reservation Point Roberts Shortcomings Limited Coverage Mean High Water 3.35 feet AMSL Adopted by geologic consultants, though not rec. for land use planning

17 Alluvial Fan Hazard Areas The following activities may be allowed when all reasonable measures have been taken to minimize risks and other adverse effects, and when the amount and degree of the alteration are limited to the minimum needed to accomplish the project purpose: A. Meets reasonable use standards B. Roads, utilities, bridges, and other infrastructure when located and designed to prevent adverse impacts on critical areas and avoid the need for channel dredging or diking or other maintenance activities that have the potential to substantially degrade river and stream functions. C. Permanent residential structures and commercial developments only if the fan has undergone a county-approved study to assess potential hazards, determine risks, and identify mitigation measures and is deemed suitable for development. The T.A. shall make this determination based on a detailed assessment a 500-year return period debris flow or the maximum credible event that could impact the alluvial fan.

19 More commonly: Application of Code Limited research and aerial photo review Site reconnaissance Interviews, if possible Test pits Recommendation typically include: Elevated stem-walls Vegetation screening Deflection berms Recommendations largely duplicated from KWL

20 Short-comings Limited to mapped alluvial fans Run-out potential lacking Cost to applicant excessive

16.16.370 Mine hazards The standards of 16.16.320 and 16.

21 Mine hazards The standards of and (D) [Uninhabited Structures permitted] shall apply.

22 Erosion and Landslide Hazards Both code sections are generally organized as follows: Allowed uses in the hazard area Any use in hazard area requires assessment Must not impact hazard in any way Hazard Buffer Areas Gives T.A. authority to establish buffers based on professional assessment. Buffer should include any potential impacted area or stabilizing condition, i.e. control stormwater, veg. Landslide HA includes an additional Hazard Management Zone ( ) Enables regulation within 300 feet of an active landslide hazard.

Erosion Hazards Slope greater than 15 percent w/ severe rill characterization by the NRCS Coastal and riverine erosion areas Frequently regulated

23 Erosion Hazards Slope greater than 15 percent w/ severe rill characterization by the NRCS Coastal and riverine erosion areas Frequently regulated under the SMP Favors avoidance and minimization Requires soft-shore, bio-eng., unless shown unsuitable Additional regulated under , Land Clearing

24 Landslide Hazard Areas Photo Credit, Doug Clark, WWU, 2004

25 Screening Tools A. Washington State Department of Ecology (WDOE) Coastal Atlas Based on mid-1970 s mapping effort that resulted in S.S. map. Admittedly potentially over- or under-estimates hazard areas. Cautions Site-specific inv. required for land-use decisions.

26 A. Upland Landslide Hazard Layer Compilation of mapped landslide deposits from multiple generations of Whatcom County mapping efforts and the WDNR WRIA-01 Compilation.

27 Slope Gradient

28 C. WDOE Feeder Bluff Map Recent (2013) publication documenting the geomorphic features of all Puget Sound Coastlines. Primary purpose to identify Feeder Bluffs, which act as sediment sources for coastline and beach replenishment. Can function as a good screening tool for identifying erosion- and landslide-prone shorelines.

29 Tools Under Development

30 Questions? Andy Wiser, L.E.G , ext

31 ,.360 Erosion Hazard Areas Allowed providing that all reasonable measures to minimize risk, and alteration is at a minimum need to accomplish project goals For coastal and riverine erosion hazard areas, the following shall be allowed as specified. A. Meets reasonable use standards B. Discharge of surface water drainage into a coastal or riverine erosion hazard area... No alternative, collection upland of hazard, properly anchored, energy dissipater C. Properly designed stormwater systems No impact to stability. D. Utility lines in no alternative is available. No impact to channel migration zone (CMZ) or impact to utility due to continued erosion. Located in channel migration zone. E. Public roads. Road prism and bridge structure not susceptibility to erosion.

32 F. Access to private development sites may be allowed to provide access to portions of the site that are not critical areas, if there are no feasible alternative alignments. Alternative access shall be pursued to the maximum extent feasible, including through the provisions of Chapter 8.24 RCW. Exceptions or deviations from technical standards for width or other dimensions, and specific construction standards to minimize impacts may be specified. G. Stream bank stabilization and shoreline protection may be permitted subject to all of the following standards: 1. Soft armoring techniques preferred. 2. Not increase adjacent erosion or impact sediment supply. 3. Not adversely impact other critical areas, or mitigation req d. 4. Comply with Shoreline Management Program (Ch. 23). 5. Hard bank armoring is discouraged Establish imminent threat 6. Erosion not being caused by upland conditions. 7. Non-structural measure not feasible or sufficient. i.e. Relocate, mitigation, drainage improvements

33 F. New residences shall be located outside identified channel migration hazard areas. Accessory structures not involving human occupancy with a footprint equal to or less than 2,500 square feet shall be allowed; provided, that they are located at the outer edge of the migration zone as defined by this chapter; and provided, that the technical administrator may allow larger accessory structures where mitigating measures are feasible and provided for by the applicant. G. New public flood protection measures and expansion of existing ones may be permitted, subject to WCC Title 17, Article 4 of this chapter, and a state hydraulic project approval; provided, that bioengineering or soft armoring techniques shall be used where feasible. Hard bank armoring may occur only in situations where soft approaches do not provide adequate protection.

34 Erosion Hazard Area Buffers A. The size of the buffer shall be based on the findings of a qualified professional and shall protect critical areas and processes and minimize the risk of property damage, death or injury resulting from erosion caused in whole or in part by the development or that the development may be subject to over the life of the development. B. The buffer shall include the uphill area subject to potential erosion, the downhill area subject to potential deposition, and any area subject to landslide as a result of erosion. C. The buffer shall include woody vegetation adequate to stabilize the soil and prevent soil movement. If the designated buffer area lacks adequate woody vegetation, the technical administrator shall have the authority to require vegetation enhancement or other measures to improve slope stability. D. Developments on sites that are directly adjacent to a wetland, or marine shoreline or other habitat conservation area as defined in Article 7 of this chapter may be subject to additional buffer requirements and standards as set forth in the subsequent articles of this chapter.

1. Surface erosion hazards regulated by WCC 20.80.730.

35 1. Surface erosion hazards regulated by WCC Shoreline Management Program dictates review, as well.

36 A. Developments that meet reasonable use standards B. Utility lines that are above-ground, properly anchored and/or designed so that they will continue to function in the event of a slope failure and will not increase the risk or consequences of slope instability... Such utility lines may be permitted only when the applicant demonstrates that no other feasible alternative is available... C. Access roads engineered and built to standards that avoid the need for major repair or reconstruction beyond that which would be required in non-hazard areas..applicant demonstrates that no other feasible alternative exists, including through the provisions of Chapter 8.24 RCW. If such access through critical areas is granted, exceptions or deviations from technical standards may be specified. D. Storm water conveyance when no other storm water conveyance alternative is available. located above-ground and designed so that it will continue to function and will not increase the risk or consequences of static or seismic slope instability or result in increased risk of mass wasting activity.

37 Standards Landslide hazard management zones. Alteration may be allowed within 300 feet of an active landslide hazard area when the T.A. determines that the following standards are met: A. The proposed alteration includes all appropriate measures to eliminate, reduce or otherwise mitigate risks to health and safety. B. The proposed alteration is located outside of an active landslide hazard area and any required buffer, as set forth in WCC C. The development will not decrease slope stability on adjacent properties, and shall not increase the risk or frequency of landslides. D. The removal and disturbance of vegetation, clearing or grading shall be limited to the area of the approved development. E. The development is outside of the area of upslope or downslope surface movement or deposition in the event of a slope failure. F. The development will not increase surface water discharge or sedimentation to adjacent properties beyond predevelopment. G.The proposed will not adversely impact other critical areas. H. Shall minimize alterations to slope contour, and be designed to minimize impervious surfaces unless needed to maintain stability.

38 Standards Landslide hazard area buffers T.A. shall have the authority to require buffers from the edge of any landslide hazard areas in accordance with the following: A. The size of the buffer shall be based on the findings of a qualified professional and shall protect critical areas and minimize the risk of property damage, death or injury resulting from landslides caused in whole or part by the development. B. The buffer shall include the uphill hydrologic contribution area and/or the uphill and downhill area subject landslide impacts. C. The buffer shall include woody vegetation adequate to stabilize the soil and prevent soil movement., the T.A. shall have the authority to require vegetation or other measure to improve slope stability. D. Developments on sites that are directly adjacent to a wetland, marine shoreline or other habitat conservation area as defined in Article 7 of this chapter may be subject to additional buffer requirements and standards as set forth in the subsequent articles of this chapter. (Ord ).

43 WCC (F): Surface erosion hazards will be regulated under WCC , land clearing.

44 VOLCANIC HAZARDS

48 TSUNAMI AND MINE HAZARDS Standards Tsunami and Seiche hazard areas. The standards of WCC and shall apply Standards Mine hazard areas. The standards of WCC and (D) shall apply.

CHAPTER GEOLOGICALLY HAZARDOUS AREAS Applicability Regulations.

CHAPTER GEOLOGICALLY HAZARDOUS AREAS Applicability Regulations. CHAPTER 19.07 GEOLOGICALLY HAZARDOUS AREAS 19.07.010 Applicability. Geologically hazardous areas may pose a threat to the health and safety of citizens when incompatible development is sited in areas of