Managing Recognized Hazards: Land Use Planning and Zoning, Strategies and Public Education/Notification

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1 Managing Recognized Hazards: Land Use Planning and Zoning, Strategies and Public Education/Notification Mark Molinari, PG, LEG AECOM Seattle, Washington

2 Introduction Overview of zoning, ordinances, codes and permit requirements related to development on and near landslides and slopes Researched and reviewed websites for selected counties and cities in areas known to have significant landslide hazards Focused on western U.S. (WA, OR, CA, UT, CO) Present selected examples to show variation of complexity and detail (or lack thereof) Discuss and present examples of land use management strategies for landslide hazards Discuss and present an example of useful information on landslides aimed at the public

3 Land Use and Development Most land use zoning and development controlled by city or county requirements Building on or near slopes is addressed by a variety of codes (building, municipal, etc.), ordinances, zoning, plans, policies, permit application requirements etc. Some are detailed and/or prescriptive, others very general Some city/county websites are difficult to navigate or find slope related requirements Few have general information or links to sites that more general information that could be beneficial to the public (e.g. U.S. or State Geological Survey)

4 Golden, CO IBC 2012 Building Code w/ additional requirements for slopes >33% Municipal Code also include additional requirements where slopes are in excess of 15% on the site Hillside standards Subdivisions: designed to minimize the disruption or reshaping of existing topographic land forms Hillside standards - Site Development (e) The top of a cut slope shall be made not nearer to a property lot line than ten feet (10'); unless a professional engineer licensed in the State of Colorado certifies that the cut will not substantially impact the lateral support of the adjacent property. (f) The toe of a fill slope greater than four (4) feet in height shall be made not nearer to property lot line than ten feet (10') or three feet (3') of setback for each one foot (1') of fill, whichever is greater.

Colorado Springs, CO Hillside Overlay Zone District with specific requirements Code includes a section titled Geologic Hazard Study and Mitigation Requires a Geologic Hazard Study Listed hazards

5 Colorado Springs, CO Hillside Overlay Zone District with specific requirements Code includes a section titled Geologic Hazard Study and Mitigation Requires a Geologic Hazard Study Listed hazards include: unstable or potentially unstable slopes, landslide areas or potential landslide areas, rockfall, debris flows and debris fans Study to be conducted by a professional geologist or licensed PE (geotechnical) Detailed guidelines, criteria, policies and requirements for preparation, submittal and review are in the City Engineering's Engineering Criteria Manual/Subdivision Policy Manual

6 Landslide Management Strategies Examples Avoidance LA County examples Zoning City of Rancho Palos Verdes, CA Landslide Moratorium and Geological Hazards Areas - City of Rancho Palos Verdes and La Conchita, CA Geologic Hazards Abatement Districts CA Geologic Hazards Zones Santa Clara County, CA Setbacks Salt Lake City and North Salt Lake City, UT; Bainbridge Island, WA; Ventura County Coastal Zone, CA

7 Zoning Rancho Palos Verdes

8 Landslide Moratorium and Geological Hazard Areas Rancho Palos Verdes, CA = an approximately 1,200-acre Landslide Moratorium Area (LMA) where there is a prohibition on the filing, processing, approval or issuance of building, grading or other permits. La Conchita, CA = new or increased area of a habitable structure within the Geological Hazard Area requires the owner to sign a waiver acknowledging: (1) that the property owner is aware that the parcel is situated in a designated Geological Hazard Area and (2) that it is their responsibility to obtain independent expert information regarding the potential risk and making a judgment thereafter regarding whether to proceed with the permit process. If proceeding, the owner must obtain a geotechnical investigation and report for review by the County, which can deny the permit request if it cannot be demonstrated that the hazard can be mitigated

9 Geologic Hazards Abatement Districts (GHADS) - California Public Resources Code Division 17. Geologic Hazard Abatement Districts, Sections Provides for the formation of local assessment districts for the purpose of prevention, mitigation, abatement, or control of geologic hazards 30+ to date Geologic hazard" defined as "an actual or threatened landslide, land subsidence, soil erosion, earthquake, or any other natural or unnatural movement of land or earth. Proposed by one of two means: (1) a petition signed by owners of at least 10 percent of the real property in the district (2) by resolution of a local legislative body Requires plan of control by Certified Engineering Geologist Plan describes in detail a geologic hazard, its location and the area affected thereby, and a plan for the prevention, mitigation, abatement, or control thereof Annual fees paid to establish a fund or payoff bonds if issued

10 Geologic Hazards Abatement Districts (GHADS) - California Land within a district need not be contiguous and may cross political boundaries Land within proposed GHAD must be benefited by it Formation of a district is required to ensure the health, safety, and welfare of the residents Advantages of Forming a GHAD Can be for public or private property or a combination of both Focus on prevention Rapid response and repair capabilities Alternative to costly, time-consuming litigation Covers absence of insurance coverage for earth movement Broader range of available remedial measures Locally autonomous exempt from local permitting requirements Increase public safety

11 Santa Clara County Geologic Hazards Zones Ordinance establishes authority to develop official Santa Clara County geologic hazard zones and maps GHZs produced by combining information from a variety of published and unpublished sources regarding the location and extent of possible faults, landslides, compressible soils, dike failure flooding, and liquefaction. Owner/applicant must submit a geologic report prepared and signed by a Certified Engineering Geologist County Geologist for review by the County Geologist prior to project approval ARTICLE 5. WRITTEN STATEMENT OF DISCLOSURE Sec. C Seller disclosure to the buyer. The seller of real property located partially or wholly within a County geologic hazard zone shall disclose in a written statement to the buyer that the property is located within such zone(s). State laws also require the disclosure of certain geologic hazards to potential buyers.

12 Santa Clara County Geologic Hazards Zones Maps

13 Santa Clara County - Index Map

14 Santa Clara County Example Map Sheet

Setbacks - North Salt Lake City, UT Adopts IBC 2013 without change Setbacks specified as function of slope height Separate requirement for slopes >1:1 Alternate

15 Setbacks - North Salt Lake City, UT Adopts IBC 2013 without change Setbacks specified as function of slope height Separate requirement for slopes >1:1 Alternate setbacks and clearances are permitted, subject to the approval of the building official. The building official shall be permitted to require a geotechnical investigation

16 Setback North Salt Lake City

17 Setbacks Salt Lake City, UT : LAND DEVELOPMENT REQUIREMENTS (BUILDING SITES) C. Soil Engineering Report Or Engineering Geology Required: 1. Soil Engineering Report: The soil engineering report required shall include data regarding the nature, distribution, and strength of existing soils, conclusions and recommendations for grading procedures, design criteria for corrective measures when necessary, and opinions and recommendations addressing the adequacy of the site under the proposed grading plan to support the proposed development. 2. Engineering Geology Report: The engineering geology report required shall include an adequate description of the geology of the site, conclusions and recommendations regarding the effect of geologic conditions on the proposed development, and opinions and recommendations addressing the adequacy of the site under the proposed grading plan to support the proposed development. This requirement may be waived by written recommendation of the building official if it is deemed unwarranted.

18 Setbacks Salt Lake City, UT H a b1 Less than 5' 0 1 5' to 30' H/2 H/5 Over 30' 15 6 a = Setback distance at toe in feet b = Setback at top in feet H = Height from toe to top of cut/fill slope PA = Permit Area (Lot Area Excluding Any Undevelopable Area) H a b1 Less 0 1 than 5' 5' to 30' H/2 H/5 Over 30' 15 6

19 Setbacks - Salt Lake City 3. Undevelopable Slopes: Any natural slopes identified on a slope classification map of thirty percent (30%) or greater shall be designated undevelopable area. In no event shall streets traverse such slopes. 4. e. Exceptions: (to cut and fill slopes) (1) No slopes shall cut steeper than the bedding plane, fracture, fault, or joint in any formation where the cut slope will lie on the dip of the strike line of the bedding plane, fracture, fault, or joint. (2) No slopes shall be cut in an existing landslide, mudflow, or other form of naturally unstable slope except as recommended by a qualified geological engineer. (3) Where the formation is exposed above the top of the cut which will permit the entry of water along bedding planes, this area shall be sealed with a compacted soil blanket having a minimum thickness of two feet (2'). The soil for this blanket shall be relatively impervious and shall be approved by the soils engineer or engineering geologist. I. Setbacks: The setback and other restrictions specified in this section are minimum and may be increased by the building official or by the recommendation of a civil engineer, soils engineer, or engineering geologist, if necessary for safety and stability

20 Setbacks Bainbridge Island, WA City of Bainbridge Island, Geologically hazardous areas. B. Purpose. The intent of this section is to prevent the potential for personal injury or loss of life or property due to flooding, erosion, landslides, seismic events, or soil subsidence. Development must not increase slope instability, and must avoid on-site and off-site impacts, as well as potential risk to structures. Preserving the existing vegetation may be an important part of minimizing those risks. C. Classification. Geologically hazardous areas shall be classified based upon landslide history and the presence of unstable soils, steepness of slopes, erosion potential, and seismic hazards. Areas in this category are a potential threat to public health, safety, and welfare when construction is allowed. While some potential risk due to construction can be reduced through structural engineering design, construction in these areas should be avoided when the potential risk cannot be reduced to a level comparable to the risk if the site were initially stable prior to construction. Classification and rating shall be based upon the risk to the environment and to development in geologically hazardous areas.

21 Setbacks Bainbridge Island, WA D. Minimum Submittal Requirements. 1. All Geologically Hazardous Areas and Buffers. a. Indemnification. An indemnification or hold harmless agreement shall be required for all projects in geologically hazardous areas and buffers except erosion hazard areas and tsunami hazard areas. The form of the agreement shall be approved by the city and executed prior to the commencement of construction or site alteration. 2. Development Design and Location. The following requirements shall apply to any land or vegetation modification or construction within a landslide hazard area and/or its buffer as described herein: a. Buffer Requirement. A buffer equal to the height of the slope or 50 feet, whichever is greater, shall be established from all edges of a landslide hazard area except where no other reasonable alternative exists, reduction may be allowed as follows:

22 Public Outreach City of Seattle City of Seattle and Santa Clara County have websites with additional general information on landslides and geologic hazards for the public City of Seattle Good Example of Public Meeting Technical Information Aimed at General Public Do s and Dont s of Slope Development/Maintenance Following Slides Courtesy of Bill Laprade of Shannon & Wilson

23 Public Notice

24 City of Seattle Public Landslide Meetings INTRODUCTION LANDSLIDES IN SEATTLE The Geology, Types Of Landslides VEGETATION ON SLOPES CITY LANDSLIDE MITIGATION PROGRAM CITY LANDSLIDE POLICY AND ENVIRONMENTALLY CRITICAL AREAS REGULATIONS (ECA) MANAGEMENT TOOLS FOR HOMEOWNERS QUESTIONS AND ANSWERS ONE-ON-ONE Questions And Answers With City & Private Sector Experts

25 City of Seattle Public Landslide Meetings INTRODUCTION Alan Justad, Community Relations Department of Planning and Development (DPD) LANDSLIDES IN SEATTLE THE GEOLOGY, TYPES OF LANDSLIDES Bill Laprade, Engineering Geologist and VP Shannon & Wilson VEGETATION ON SLOPES Mark Mead, Urban Forester Seattle Parks and Recreation CITY LANDSLIDE MITIGATION PROGRAM Bill Benzer, Senior Geotechnical Engineer Keith Ward, Senior Geotechnical Engineer Seattle Public Utilities CITY LANDSLIDE POLICY AND ENVIRONMENTALLY CRITICAL AREAS REGULATIONS (ECA) Alan Justad, DPD MANAGEMENT TOOLS FOR HOMEOWNERS Bill Laprade, Shannon & Wilson QUESTIONS AND ANSWERS ONE-ON-ONE QUESTIONS AND ANSWERS WITH CITY & PRIVATE SECTOR EXPERTS

26 City Experts Seattle Public Utilities Seattle Parks and Recreation Seattle Department of Transportation Seattle Department of Planning and Development

27 Outside Experts American Society of Civil Engineers (Geotechnical Group) Association of Environmental & Engineering Geologists ABC Construction International Society of Arboriculture

28 Development Regulations for Landslide-Prone Property in Seattle Environmental Critical Areas Ordinance Stormwater, Grading and Drainage Ordinance Professional Assessment Permit/Inspections

29 Environmentally Critical Areas: Geologic Hazard Areas in Seattle Known landslide areas Potential landslide areas (over 15% slope with certain soils) Steep slopes (40% or greater average slope) Liquefaction-prone

Don t List Don t put fill on steep slope. Don t concentrate water on slope if you don t have anything better. Don t denude vegetation on slope without revegetation plan.

30 Don t List Don t put fill on steep slope. Don t concentrate water on slope if you don t have anything better. Don t denude vegetation on slope without revegetation plan. Don t put fill on slopes, especially top. Don t cut into toe of slope. Don t remove tree stumps. Don t place yard debris on slopes. Don t walk away from it. Don t install permanent irrigation system in LPAs.

31 Do List Maintain drainage. Perform periodic inspections of property (before and during storms). Check weep holes on walls. Do be alert during and following storms. If you have an irrigation system, shut it off and check it out seasonally. Keep fill and yard waste off slopes. Leave stumps in the ground.

California Susceptibility Map and Loss Simulation - CDMG State Landslide Deep-seated Landslide inventory map as a basis Use rock strengths based on rock type and combine with slope steepness Generate

32 California Susceptibility Map and Loss Simulation - CDMG State Landslide Deep-seated Landslide inventory map as a basis Use rock strengths based on rock type and combine with slope steepness Generate landslide susceptibility map using HAZUS methodology Use estimates of direct private property loss and Caltrans infrastructure loss data from several historical storms Estimate loss ratios Simulate losses from future storm scenario using ARkStorm Source: Wills et al, 2014 ASCE Natural Hazards Review

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