1 October 4, 2016 Seabreeze Associates Limited Partnership Robert B. Fultz, General Partner 865 Highland Drive Boulder Creek, California 95006 Subject: Preliminary Site Investigation and Dune Hazard Report Proposed 9 Lot Residential Subdivision Tax Lot 224, Parcel 2 Partition Plat 2006-43 Map 5S, 11, 36BC Neskowin, Tillamook County, Oregon Dear Mr. Fultz: Introduction and Background As you requested, I am pleased to submit this Dune Hazard Report for the subject property based on my preliminary site investigation. This report had been prepared in general accordance with Tillamook County Land Use Ordinance (TCLUO) 3.530 Beach and Dune Hazards Overlay (BD) Section 5: Site Development requirements; (B.) Dune Hazard and Modified Dune Hazard Reports; (3.) Dune Hazards Report; (a.) Preliminary Site Investigation; (3) preliminary site report. To the extent practical, bold headings of this report correspond with the Dune Hazards Report content required by TCLUO 3.530, (5.) (B.) (3.) (a.) (a.-j.) Proposed development responses to TCLUO 3.530, (5.) (B.) (3.) (c.) Summary Findings and Conclusions, are also presented at the end of this report. R. Warren Krager, R.G. C.E.G. conducted the preliminary site investigation on September 8, 2015. I visited the site again on March 22, 2016. The work included limited subsurface exploration on the subject property using hand tools, disturbed soil sampling, observation of the near surface soil and shoreline observation from the active Pacific Ocean beach or crest of the existing shoreline protection revetment. The following information sources were used in this investigation and report: Proposal Rock Cove Preliminary Plat, dated September 19, 2016, Sheet 1/6 Preliminary Site Layout, Sheet 2/6 Site Vegetation, Sheet 3/6 Preliminary Fill Plan, Sheet 4/6 Conceptual House layout Plan, Preliminary, Sheet 5/6 Preliminary Utility Layout, and Sheet 6/6 Preliminary Drainage Plan, prepared by Jason Morgan, P.E., Morgan Civil Engineering, Inc. (MCE) for Seabreeze Associates LP, Tax Lot 224 Map 5S 11W36BC.
2 100-Year 24 Hour Storm Study with Technical Appendix, Rock Cove Development, Tax Lot 224, Map 5S 11W, 36BC, prepared for Sea Breeze Associates, by Conaway Engineering, dated September 15, 2016. Preliminary Piling Analyses for Proposal Rock Cove by Stricker Engineering, LLC, dated May 25, 2016. Environmental Geology of the Coastal Region of Tillamook and Clatsop Counties, Oregon, Oregon Department of Geology and Mineral Industries (DOGAMI), Bulletin 74, 1972. Geologic Map of the Tillamook Highlands Northwest Oregon Coast Range, Nehalem 15 Minute Quadrangle, United States Geologic Survey (USGS), Open File Report 94-21, 1994. United States Department of Agriculture (USDA) Web Soil Survey (http://websoilsurvey.sc.egov.usda.gov/app/websoilsurvey.aspx) Evaluation of Coastal Erosion Hazards Zones Along the Dune and Bluff Backed Shorelines in Tillamook County, Oregon, DOGAMI Open-File Report O-01-03, by Jonathan C. Allan and George R. Priest, 2001. DOGAMI Open-File Report O-07-01, Assessing the Temporal and Spatial Variability in the Neskowin Littoral Cell, Oregon. Jonathan C. Allan and Roger Hart, 2007. Oregon Beach and Shoreline Mapping and Analysis Program: 2007-2008 Beach Monitoring Report, DOGAMI Open-File Report O-08-15, by Jonathan C. Allan and Roger Hart, 2008. National Assessment of Shoreline Change: Historical Shoreline Change Along the Pacific Northwest Coast, USGS Open File Report 2012-1007, By Peter Ruggiero, Meredith G. Kratzmann, Emily A. Himmelstoss, David Reid, Jonathan Allan, and George Kaminsky Oregon Beach and Shoreline Mapping and Analysis Program: Pacific Northwest Estuaries and Shores, http://www.oregongeology.org/sub/nanoos1/index.htm. Beaches and Dunes of the Oregon Coast, USDA Soil Conservation Service and Oregon Coastal Conservation and Development Commission, March 1975. USDA Soil Survey of Tillamook Area, issued August 1964. DOGAMI LIDAR Viewer, (http://www.oregongeology.org/sub/lidardataviewer/index.htm), accessed September 1, 2016.
3 Google Earth Aerial photographs of the Neskowin, Oregon area, photo dates: May 5, 1994, August 15, 2000, June 15, 2003, June 29, 2005, August 1, 2011, July 6, 2012, and July 30, 2014. Tillamook County Land Use Ordinance Article 3.500 Section 3.530 Beach and Dune Overlay (BD), Adopted May 27, 2015. Subject Property 20.54-foot wide, 260-foot long portion of property with ocean shoreline and beach exposure. Figure 1- Site Location Plan, Portion of Tillamook County Tax Lot Map 5S1136BC.
4 Site Description The general location of the subject property is shown in Figure 1. The subject property consists of Parcel 2, Tax Lot 224 of partition plat 2006-46 on Tillamook County Tax Map 5S 11 36BC. The property is a vacant, partially wooded, 3.26-acre parcel, surrounded on all sides by public streets, and by a mix of vacant and developed single-family residential building lots and a public beach access pathway. The exception to the street-enclosed property boundary is a 20.54-foot wide pan-handle strip of land that extends 260 feet west alongside the public beach access right-of-way from Surf Road onto the Pacific Ocean beach. Approximate location of 20.54- foot wide beach front portion of Tax Lot 224. Photo 1 - Existing shoreline protection revetment during low tide on September 8, 2015. The western margin of Surf Road effectively forms the western boundary of Tax Lot 224. The 260-foot westerly pan-handle extension connecting the property to the beach is bordered on the south by public land with existing beach access. To the north of the pan-handle, developed beach-front residences occupy Tax Lots 1600, 1700, 1800, and 1900 on the west side of Surf Road. Tax Lot 2000, also west of Surf Road, is currently undeveloped but is graded, landscaped and fenced. Tax Lot 224 has no active beach or dune frontage other than the 20.54-foot width of the western terminus of the pan-handle that lies south of Tax Lot 2000 adjacent to the existing public beach access. Proposed Project For the purposes of this dune hazard report, there are no ocean front structures or land division improvements planned for the 20.54-foot wide panhandle strip that extends west of Surf Road to the revetment protected shoreline and ocean beach. Development will be limited to portions of the property located east of Surf Road where beach and dune hazards and shoreline erosion risk are considered negligible.
5 This inland portion of Lot 224, which will be developed as a 9-Lot subdivision according to preliminary plat civil engineering design plans by MCE, is subject to TCLUO Section 4.130: Development Requirements for Geologic Hazard Areas. Land use planning, civil engineering design and geologic hazards review are underway concurrently for the proposed subdivision of Tax Lot 224. A separate Geologic Hazard Report will be submitted for Tillamook County Planning review concurrently with this Preliminary Site investigation and Dune Hazard Report for Tax Lot 224. According to my review of the MCE Conceptual House Layout Plan, the nearest home in the subdivision would be more than 270 feet from the west end of the panhandle extension of Tax Lot 224 where beach access and shoreline protection exist. Identification of Dune Landforms, TCLUO 3.530, (5.) (B.) (3.) (a.) (3.) a. According to project background information that you provided, Tillamook County Planner Sarah Absher indicates that Tax Lot 224 contains three dune classifications that need to be addressed. These are: 1) Recently Stabilized Foredune, FD 2) Active Foredune, FDA and 3) Wet Deflation Plain, WDP. These dune classifications are taken to be in accordance with dune landform definitions in Beaches and Dunes of the Oregon Coast, USDA, Soil Conservation Service and Oregon Coastal Conservation and Development Commission, March 1975. Figure 2, shows the USDA mapped Dune categories of the project area. Approximate location of subject property Figure 2- Sand Dunes Map from Beaches and Dunes of the Oregon Coast, 1975. The USDA map indicates dune landforms FD, FDA and WMF in the project area in 1975. There is no WDP dune category mapped in the project area by the USDA. From my site visits, it is my interpretation that Tax Lot 224 no longer has an Active Foredune zone, FDA, as originally mapped in this area by the USDA for their 1975 publication. The shoreline dunes have been modified by development of lots west of Surf Road and their subsequent shoreline protection. High tides now reach the base elevation of the existing shoreline protection boulder revetment, effectively preventing any active dune formation to the west of the revetment. The Recently Stabilized Foredune zone, FD in interpreted to be present on Tax Lot 224 near the western terminus of the 20.54-foot wide pan-handle extension of the property. The ocean
6 shoreline and beach access pathway in this area is lined with rip-rap revetment. Most of the natural dune landforms studied and mapped by the USDA and others have been erased and modified by previous development and grading of the ocean front lots that lie west of Surf Road. Approximate location of 20.54- foot wide beach front portion of Tax Lot 224. Photo 2- View to north at public beach access south of Tax Lot 2000. The recently stabilized fore-dune zone, FD, on the pan-handle portion of Tax Lot 224 has now been engineered into an ocean front erosion protection boulder revetment backed by graded building lots and public access right-of-way. The FD zone is now interpreted to extend eastward from the toe of the rip-rap protected slope revetment and includes the graded ocean front lots, homes, yard and driveway areas west of Surf Road. The Wet Deflation Plain, WDP, zone, according to the Beaches and Dunes of the Oregon Coast definition, are broad inter-dune areas which are wind scoured to the elevation of the summer water table. Wet deflation plains are usually mapped landward of the FDA and FD dune forms. However, from my site visit and map review, I do not find that Wet Deflation Plain, WDP, zone dune forms are present on Tax Lot 224. The heavily vegetated and tree covered character of the inland portion of Tax Lot 224 is not consistent with a with a coastal dune wet deflation plain. Instead, the bulk of Tax Lot 224 appears to be mapped by the USDA in a landform classification called Wet Mountain Front, WMF, see Figure 2. The WMF zone is not a dune mapping unit but is directly associated with coastal dunes because it represents wet, sometimes closed depression areas created by dune blocked drainages.
7 Excluding the shoreline protected FD zone near the west end of the 20.54-foot wide westerly pan-handle extension, there is no dune activity or dune landforms recognizable on Tax Lot 224. This inland portion of Tax Lot 224 is largely forested with taller trees estimated at 50 to 60 feet in height. This inland area east of Surf Road is generally enclosed and protected by flanking headlands and has little to no exposure to wind-blown dune sand from the active ocean beach. History of Dune Stabilization in the Area, TCLUO 3.530, (5.) (B.) (3.) (a.) (3.) (b.) Google Earth aerial images indicate that by 1994, three of the four developed ocean front lots to the west of Surf Road and Tax Lot 224 contained homes. The average width of the coastal foredune profile, as measured from Surf Road, was about 200 feet at that time. In the August 15, 2000, Google Earth aerial image, all four of the existing homes that occupy the lots west of Surf Road had been built. By this time, the graded foredune, measured from Surf Lane, had decreased in width to less than 180 feet and shoreline protection revetment had been placed across the eroding foredune slope on Tax Lots 1600, 1700, 1800, 1900, 2000. Revetment was also placed at that time for the 20.54-foot wide panhandle extension of Tax Lot 224 and the public beach access to the south. Subject Property 20.54-foot wide panhandle extension of Tax Lot 224 Photo 3 Existing shoreline protection and development in project area. Photo source: The Oregon Map Tax Lot Viewer. History of Erosion and Accretion in Area, TCLUO 3.530, (5.) (B.) (3.) (a.) (3.) (c.) The Neskowin littoral cell runs from Cascade Head on the south to Cape Kiwanda on the north.
8 On the south end at the town of Neskowin, coastal erosion has been particularly severe in response to historically recent major El Niño events and possibly by the progressive rise in sea level and increase in wave heights in recent decades. According to Allen and Hart, 2007, in their comparative studies of short term erosion rates, the Neskowin Littoral cell had one of the highest rates of erosion in Oregon with over 3 feet per year, averaged over 261 transects. Variability in the short term was also relatively high, with change rates ranging from 10 feet to 8 feet per year. Site Location Note: DOGAMI mapped creek. Not 1998 shoreline. Figure 3- DOGAMI Open-File Report O-01-03 Coastal Erosion Hazard Zones. DOGAMI Open-File Report O-01-03 maps most of the subject property in moderate (amber) to low (yellow) and non-existent coastal erosion hazard zones. It should be noted that the panhandle property extension west from Surf Road is in the high Coastal Erosion Hazard Zone. Long before construction of Surf Road and development of the ocean front lots to the west of Tax Lot 224, there were areas of open sand on the subject property. The 1964 air photo used in the USDA Soil Survey of Tillamook Area, Oregon shows what may be open sand, grass covered area and a few small trees in the general area of the property.
9 Approximate site location in area mapped as active dune, Ad. Figure 4 1964 USDA Soil Survey of Tillamook Area, Oregon. Soil map and air photo of project area. It appears that the highest tides and storm waves or tsunami inundation events, have at times in the past, deposited ocean drift logs several hundred feet inland onto the subject property east of Surf Road. I observed a large log that I interpret as having been deposited during a past high ocean wave event. It is also possible that the log was pushed into position during grading of the lots west of Surf Road. This log lies at about elevation 20 feet above mean sea level.
10 Photo 3 Possible ocean drift log deposited by ocean storm wave surge, now more than 200 feet inland from the rip rap protected shoreline. General Topography and Spot Elevations, TCLUO 3.530, (5.) (B.) (3.) (a.) (3.) (d.) A topographic survey plan was provided for my use and reference, and is shown in Figure 5. Full topography for the 20.54-foot wide western extension of Tax Lot 224 along the public access way was not available. However, the eastern end of the pan handle at the intersection of Surf Road and Seasand Lane lies at elevation 22 feet above mean sea level. Elevations on the interior of the property surrounded by existing streets ranges from about 16 feet to 23 feet above mean sea level. Some of the eastern part of the site has been mapped by others as containing wetland areas. The level grassy meadow area in the eastern half of Tax Lot 224 corresponds to the lowest site elevation, at about 16 feet above mean sea level. The highest elevation on the property appears to be located at the crest of the roadway embankment near the eastern corner of the property. Higher ground above elevation 19 feet also occurs on the western edge of the property where fill for Surf Road was placed.
11 Subject Property Figure 5 Existing elevations and proposed fills on Tax Lot 224 from Proposal Rock Cove Preliminary Plat, Preliminary Fill Plan, Sheet 3 of 6, Tax Lot 224, Map 5S 11W36BC, prepared by Morgan Civil Engineering dated September 19, 2016. Slopes on Tax Lot 224 are mild to non-existent except for existing manmade roadway embankment on the eastern margin and other graded roadway shoulders and beach access slopes. In general, the elevation on the western part of the property is about three feet higher than the level meadow on the eastern part of the site. The lots to the west of Surf Road are also higher in elevation. However detailed topography or spot elevations for these lots was not available. The Light Detection and Ranging (Lidar) image below provides a visual perspective of local topographic relief, geographic features, and the general location of the subject property with the Pacific Ocean on the west and the slopes of Cascade Head to the south.
12 Proposal Rock Site location Figure 6 DOGAMI Lidar viewer shaded relief bare earth topographic interpretation image. Base Flood Elevation and areas subject to flooding, including flood areas shown on NFIP maps of Tillamook County, TCLUO 3.530, (5.) (B.) (3.) (a.) (3.) (e.) According to the FEMA Flood Map in Figure 7, the subject property is not mapped in a flood zone.
13 Location of Tax Lot 224 Figure 7 - FEMA Flood Map service center, Map of Neskowin, Oregon Area. Location of Perennial Streams or Springs in Vicinity, TCLUO 3.530, (5.) (B.) (3.) (a.) (3.) (f.) The are no identified perennial streams or springs on Tax Lot 224. Local unnamed storm water drainages generally flow into a low area on eastern portion of Tax Lot 224. No known drainage outflow has occurred from Tax Lot 224. Location of State Beach Zone Line, TCLUO 3.530, (5.) (B.) (3.) (a.) (3) (g.) See Figure 1 on page 2 of this report. Location of Beach Front Protective Structures in Vicinity, TCLUO 3.530, (5.) (B.) (3.) (a.) 3. (h.) Beach front protective structure occurs on Tax Lots 1600, 1700, 1800, 1900, 2000 and the 20.54-foot wide panhandle extension of Tax Lot 224. See Photo 1 and Photo 2 of this report. Elevation and Width of Foredune Crest, TCLUO 3.530, (5.) (B.) (.3) (a.) (3.) (i.) Detailed surveys of elevation and width of foredune crest have not been provided for the panhandle extension portion of the property. However, for this project these dune measurements are considered irrelevant because the pan-handle portion of this lot has been previously graded and improved with the beach access and coastal erosion protection revetment. Any natural dune features on Tax Lot 224 have been substantially modified or erased entirely by previous ocean front development. To a much greater extent, any natural dune landforms on Tax Lots 1600, 1700, 1800, 1900, 2000, have also be previously been modified by dune grading, home development and placement of beach front protective rip rap revetment structure. Permits for the home construction, grading and shoreline protection work for the ocean front properties west of Tax Lot 224 were not researched as part of my work scope for this report.
14 Summary Findings and Conclusions TCLUO 3.530, (5.) (B.) (3.) (c.) According to Tillamook County Code the Preliminary Site Investigation report must include the following summary findings and conclusions: 1) The proposed use and hazards it might cause to life, property and the natural environment; Applicant response: The proposed 9 Lot subdivision of Tax Lot 224 is not located in a Beach and dune hazard area or high rick shoreline erosion zone. The proposed development will not result in hazards to life, property and the natural environment. 2) The proposed use is reasonably protected from the described hazards for the lifetime of the structure; Applicant response: The proposed 9 Lot subdivision of Tax Lot 224 is reasonably protected from dune and shoreline hazard risks for the typical design life of the subdivision and its infrastructure. 3) Measures necessary to protect the surrounding area from any hazards that are a result of the proposed development; Applicant response: There are no dune or shoreline hazards that increase as a result of the proposed development. Therefore, no measures are considered necessary to protect the surrounding area from hazards that are a result of the proposed subdivision. 4) Periodic monitoring necessary to ensure recommended development standards are implemented or that are necessary for the long-term success of the development; Applicant response: Based on the limited dune and shoreline hazards associated with proposed development of Tax Lot 224, it is not considered necessary to recommend periodic monitoring of dune or shoreline conditions to ensure recommended development standards are implemented or that are necessary for the long-term success of the development. Conclusions I can foresee no dune or shoreline concerns for the proposed residential development of Tax Lot 224 as the proposed lots will have no direct no ocean shoreline frontage. The adjacent residential lots west of Tax Lot 224 have been previously graded, developed and provided with shoreline erosion protection revetment. Proposed developable areas of Tax Lot 224 are located east and inland of the previously developed and protected oceanfront lots. It my professional opinion that this preliminary site investigation and Dune hazard report has adequately addressed known beach and dune hazards and ocean shoreline erosion conditions relevant to the proposed subdivision of Tax Lot 224. If shoreline access conditions will remain unchanged as a result of the proposed subdivision, I see no reason for recommendation of a detailed site investigation and dune report.
15 The west end of the 20.54-foot-wide panhandle extension of Tax Lot 224 has actual shoreline exposure, but this portion of the property has been in previous use as part of the public beach access from Surf Road and will to likely continue to function as such. Accordingly, recommendation of development standards is not warranted under dune hazard criteria. Limitations The engineering geologic services performed for this preliminary site investigation and dune hazards report have been conducted with that level of care and skill ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is made. Because of the dynamic nature of the coastal environment, as well as the influence of relatively unpredictable events, such as El Niño or La Niña climatic events, severe storms, earthquakes, or sea level rise, accurate long-term prediction of geologic hazards for this property and building site is not possible. The interpretations, conclusions and recommendations in this report are based on available short to intermediate term coastal erosion records and trends. Conditions beyond our knowledge or control may affect beach and dune hazards or other geologic hazard risk to this site and region. If you have any questions regarding the information presented in this report, please do not hesitate to contact me at 360-903-4861 or warrenkrager@gmail.com. Sincerely, R. Warren Krager, R.G., C.E.G. Oregon Licensed Engineering Geologist E-957