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HomeMy WebLinkAboutGEO2023-00073 BLD2023-01135 Replace Bulkhead - BLD Engineering / Geo-tech Reports - 8/17/2023 Aspect CONSULTING August 17,2022 Nye Tides LLC 6249 Old Olympic HWY SW Olympia,WA 98512 Re: Geotechnical Assessment of Bulkhead Replacement Project 23022 North Highway 101 Hoodsport, Washington Project No. 220371-A-0I Dear Ms. Wendy Kramer and Mr. Daniel Nye: This letter summarizes Aspect Consulting, LLC's(Aspect)observations, conclusions,and recommendations regarding the proposed replacement of the existing concrete bulkhead(Project) along the waterfront of the single-family residential property located 23022 Highway 101 North in Hoodsport,Washington(Site),also known as Mason County(County)parcel number 422235000006. The purpose of our study was to observe Site conditions,evaluate shoreline and slope geomorphic processes,assess impacts of these processes on the stability of the uplands, and provide design recommendations of the proposed bulkhead replacement. Aspect completed this evaluation in accordance with our agreed-upon scope of work dated July 7,2022. Project Description The Site is located along the western shore of the Hood Canal.Tidal and wave action have damaged the existing concrete bulkhead and are endangering site improvements, including the residence. Replacement of the damaged bulkhead is recommended to provide long-term protection of the residence. Sealevel Bulkhead Builders,Inc. (Sealevel)has proposed to complete a bulkhead replacement design based on our recommendations and intends to be the contractor for the replacement. This letter provides our recommendations and opinions regarding geotechnical elements of the proposed bulkhead replacement. Surface Conditions Aspect assessed the surface conditions of the Site through a literature review and by field observations. We conducted a geotechnical reconnaissance on July 25,2022. To supplement our field observations,we reviewed County parcel maps,County parcel information,geologic maps, geomorphic maps, light detection and ranging(LiDAR)studies and images, and current and historical aerial photographs and topographic maps. The following sections discuss the results of our assessment. Nye Tides LLC August 17,2022 Project No. 220371-A-01 Site Conditions The Site occupies 0.8 acres and is roughly rectangular in shape(Figure 1; County,2022).The property measures approximately 115 feet east to west and 270 feet north to south and is accessed by an asphalt-paved, gated,shared driveway extending from United States Highway 101 North (Hwy 101)on the west side of the parcel(County, 2022). The Site is developed with a one-and-a- half-story,2,023-square-foot residence near the southern end of the Site with a 640-square-foot detached garage to the north,both built in 1946(County,2022). ��,.dam, � e°•`►, +,�' ►e L � et < r ' Figure 1. County Parcel Map (County, 2022) A 7-foot-tall,concrete bulkhead lines the shoreline from the southern property line extending about 38 feet north of the detached garage(Photograph 1).The septic tank is located less than 10 feet east of the detached garage and is routed to two,20-foot-long drainfield lines abutting the north end of the residence and the concrete bulkhead. The residence is about 7.4 feet west of the bulkhead. Page 2 Nye Tides LLC August 17,2022 Project No. 220371-A-01 s4 .0 }Xy ,t y �l F Photograph 1. Oblique aerial image of Site including residence, garage, boat ramp, and along the shoreline. July 24, 2016 (Ecology, 2022). Topography The Site slopes steeply down from Hwy 101 to the relatively level area of the residential development,encompassing about two-thirds of the Site. The northern third of the Site is undeveloped, unimproved shoreline abutting Hwy 101. The 10-to 15-foot-tall slope between Hwy 101 and the residential development is inclined about 33 degrees(70 percent, 1.5 horizontal:l vertical);the residence is located 26.5 feet east of the toe of this slope. The toe of the slope is retained by two 2.6-to 3-foot-tall concrete and masonry block retaining walls spanning 80 feet in length from the end of the driveway to north of the garage. Shoreline Structures A 175-foot-long, 7-foot-tall concrete bulkhead lines the shoreline in the area of the residential development(Photograph 2). The bulkhead inclines 88 degrees on average except below the south lawn where the bulkhead has a 5 degree forward lean. Much of the bulkhead is in poor condition with multiple wide-aperture vertical and horizontal fractures spanning 142 linear feet of wall (Photograph 3). Two sets of steps extend down from the residence over the bulkhead to the beach. One set is just north of the residence and the other is at the far northern end of the bulkhead and in the center between the residence and garage. A boat rail system is also installed east of the garage. At the southern end of the bulkhead are several deteriorated concrete groins extending outward from the bulkhead next to several rotting creosote-treated timber pilings(Photograph 4). Page 3 Nye Tides LLC August 17, 2022 Project No. 220371-A-01 �. y' tllE -NNP, rrr err �'t a i MEER E Photograph 2. Concrete bulkhead and residence on the Site. Note multiple cracks on the face (yellow arrows) and cinder blocks (orange arrow) with steel rail at the top of the wall. Timber piles (bottom left), groins (bottom left and center), concrete stairs (bottom center right), and boat rail (bottom right). View to the north. 1/1 IpU/1 _ /UIU/ 1/M/q I�IIq rn 1#1 _ aft' _ _ arsrnr p1 1ttt. 1vl, 11 N ,. a w�4 �• ::.Fc t Photograph 3. Annotated photograph of a section of bulkhead showing multiple vertical (red lines) and horizontal (yellow lines) fractures. Some fractures have been previously filled by homeowners. View to the west. 11,we 4 Nye Tides LLC August 17,2022 Project No. 220371-A-01 Vt K'. Photograph 4. Concrete steps installed in 2011 at the far northern end of the bulkhead and a portion of concrete bulkhead replaced in 2010. View to the west. Based on our review of historical records, it is unknown when the bulkhead was originally constructed. The bulkhead was likely needed in order to construct the residence;therefore, it is assumed that the bulkhead was constructed in or before 1946(Google,2022;NETR,2022; Ecology,2022;DNR,2019). The bulkhead appears to have been repaired and modified multiple times since installation.There are 2 feet of stacked and mortared cinder blocks and steel railing at the top the bulkhead that appear stylistically different and in better condition than the rest of the wall. County records indicate the northern 33 linear feet of bulkhead was replaced in 2010 and an additional set of concrete stairs were installed in 2011 (Photograph 4;County,2022). The lower 3 to 5 feet of wall appears to be a different color than the upper portion of the bulkhead and shows signs of frequent inundation(presence of barnacles and seaweed attached to the concrete;Photograph 5). The staining on the wall face and the lack of vegetation on the beach indicate that the ordinary high water mark(OHWM) line is above the base of the bulkhead. Page 5 Nye Tides LLC August 17,2022 Project No. 220371-A-01 Er�.rRr F. Photograph 5. Concrete bulkhead north of the residence showing concrete steps, newer- looking cement bricks, and cleaned lower portion of bulkhead. View to the west. Vegetation Vegetation on the property consists of grass, landscaped woody and herbaceous shrubbery,Big Leaf Maple trees,Madrona trees,St. John's Wort groundcover,and many evergreen trees(mostly Douglas Fir)on the hillslope between Hwy 101 and the residence. At the Site,the evergreens are generally straight on the slope up from the residence;however,the majority of the evergreens on the unprotected shoreline slope north of the bulkhead have slight to severe trunk curvatures and lean(Photograph 6). In general, straight,vertical-growing evergreens indicate stable slope conditions and leaning trees, or curving trunks, indicate slope instability. We did not observe hydrophilic vegetation that would indicate saturated or perennially wet soil conditions anywhere on the parcel itself. Page 6 Nye Tides LLC August 17,2022 Project No. 220371-A-01 ' 3 ar 1 R R v ' •�� , t y;. `+ .'tip '!�� � k,,.`.. Photograph 6. Curvature and lean in trees growing in the bluff north of the residence on the Site. Hwy 101 at the top of the slope. View to the north. Drainage The garage does not have a roof gutter and downspout system. The west side of the residence roof has one gutter section with no downspout(Photograph 6). It appears at one time there was an underground,terra-cotta,clay pipe system that conveyed water from downspouts to an outlet on the bulkhead,but all downspouts have since been disconnected(Photograph 8). Weep holes are located along the 33 feet of newer bulkhead installed in 2010.about 2 feet above the beach surface. Several terra-cotta,pipe drainage outlets are located along the face of the older concrete bulkhead. We observed no seepage through the bulkhead structure during our reconnaissance. Surface drainage and groundwater conditions at the Site will vary with fluctuations in precipitation, Site usage(such as irrigation), and off-Site land use. Page 7 Nye Tides LLC August 17,2022 Project No. 220371 -01 s _ Photograph 6. Gutters on the west side of the residence without a downspout. View to the east. w, 4 r; M d ' ` k' '.Ut L'iri. ... ,AsKs']IAts..i lr 3 a'S. ' .: .i�.d' t'K.d[.cs' &1s"�li Photograph 7. Disconnected downspout and terra-cotta, clay lined pipe. Surticial Beach and rdal Conditions The beach surface extends from the base of the bulkhead and gradually slopes down to the Hood Canal with inclinations between 8 and 10 degrees(14 to 18 percent). During our reconnaissance, the tide reported at nearby Union,Washington, was between 1 and 0 feet above mean lower low water(MLLW; Tides,2022). We observed the water line approximately 50 feet east of the bulkhead. The beach surface along the base of the bulkhead was composed of fine to coarse gray sand with gravel and few cobbles to approximately 10 feet east of the bulkhead where the dominant clast size became gravel grading into cobbles further down the beach profile. We found Page 8 Nye Tides LLC August 17,2022 Project No. 220371-A-01 accumulations of predominantly sand-sized drift sediments on the south side of the groin structures, as well as the south side of the central concrete stairs. Shoreline Processes The Site is located on the western shore of Hood Canal at a location where the canal is about 1.4 miles wide. The Site has a maximum overwater fetch(the horizontal distance over open water where the wind generates waves)of about 20 miles to the north and about 5 miles to the southeast. During the winter months,the predominant direction of low-pressure systems entering the Puget Sound area is from the south and southwest. The shoreline at the Site is subject to wave impacts from storm-driven waves within the canal, small vessel wakes,and sediment transport due to tidal fluctuations. Drift cells are defined as discrete zones along the shoreline that contain areas of sediment erosion, transport corridors, and deposition or accretion areas. The data regarding coastal processes indicate the Site is a transport zone traveling right to left, north to south(Ecology,2003). Beach levels tend to fluctuate based on the season and as a result of storms. Storm-driven wind, currents,and wave forces tend to remove beach material from the base of the bulkhead and cause the beach to lower(degrade). Calmer periods(such as during the summer)may result in material accumulating on the beach,causing the beach to raise(aggrade). Based on our observations,the shoreline appears to be relatively stable. Geology The geologic map of the Site area indicates the Site is underlain by pre-Fraser Olympic sourced glacial drift, undivided(Qapd;Polenz et al., 2012).Glacial drift is a general term for soils deposited during a glacial stade that include materials that have been glacially overridden and those that have not. Till is material deposited under the advancing and retreating continental glacier and recessional outwash is associated with the retreat. During our reconnaissance,to the north of the garage,we observed outcrops of interbedded dense,' dry to slightly moist,gray to brown, silty sand(SM)2 with gravel and gravel(GP-GM)with sand and cobbles,which we interpreted to be recessional outwash associated with the glacial drift, consistent with the geologic map.We advanced two hand explorations 1.5 feet deep on the beach in front of the bulkhead but were unable to dig below beach deposits.No soil exposures were observed elsewhere at the Site. Alternatives Analysis The Revised Code of Washington(RCW)Section 77.55.23l(1)(b)(WSL, 2021)was revised in July 2021 to require an Alternatives Analysis following a prescribed flow chart that considers options I Relative density was assessed in the hand explorations with a 1/2-inch-diameter,pointed steel T-probe at various depth intervals and effort to advance the auger.Based on this,a relative density was assigned to the unit. 2 Soils were described according to ASTM International(ASTM)D2488,Standard Practice for Description and Identification of Soils(Visual-Manual Procedure;ASTM,2018). Page 9 Nye Tides LLC August 17,2022 Project No. 220371-A-01 ranging from complete bulkhead removal to in-kind hard structure replacement. The following are the Alternatives,from most preferred to least preferred: (i)Remove the structure and restore the beach; (ii)Remove the structure and install native vegetation; (iii)Remove the structure and control upland drainage; (iv)Remove the structure and replace it with a soft structure constructed of natural materials, including bioengineering; (v)Remove the hard structure and construct upland retaining walls; (vi)Remove the hard structure and replace it with a hard structure located landward of the existing structure,preferably at or above the ordinary high water line; or (vii)Remove the hard structure and replace it with hard shoreline structure in the same footprint as the existing structure. Below we present our considerations for each Alternative and our conclusions on the most feasible approach to protecting the Site infrastructure. "Feasible"means available and capable of being done after taking into consideration the cost, existing technology,and logistics in light of overall Project purposes per RCW 77.55.231(1)(c)(WSL,2021). Alternatives i through iv: Remove the structure (bulkhead) The residence and septic system are being protected from shoreline processes. If the bulkhead were removed,the residence and septic system would be at risk of falling into the waterway imminently, within 3 years.The inclination from the shoreline to the residence and septic system is greater than 45 degrees. The soils behind the bulkhead are not stable at this inclination and with the addition of shoreline processes,the slope would fail immediately. Unprotected shorelines or soft structure shorelines are effective for slopes less than about 10 degrees. The residence depends upon the hard structure shoreline protection.Natural drainage and stormwater from the residence and garage should be collected,tightlined to the bulkhead,and discharged through a diffuser,as described in the Drainage section. Alternatives i, ii, iii,and iv are not feasible. Alternative v: Remove the structure and construct upland retaining walls The distance between the bulkhead to the residence(7.4 feet)and to the drainfield(a few feet) is extremely limited,creating insufficient space to construct upland retaining walls. The buildable area on the Site is very limited,therefore moving the residence and utilities farther landward from the bulkhead in order to construct an upland retaining wall is not feasible. Therefore,we conclude that constructing an upland retaining wall is not feasible,as defined by RCW 77.5 5.23 1(1)(c) (WSL,2021). Alternatives v is not feasible. Page 10 Nye Tides LLC August 17,2022 Project No. 220371-A-0I Alternatives vi and vii:Replace failed hard structure and replace with hard structure Alternatives vi and vii call for a hard bulkhead landward of the existing bulkhead or at the same location of the existing bulkhead,respectively. In our opinion,a new bulkhead can be feasibly constructed landward of the existing bulkhead and then the existing bulkhead removed;therefore, Alternative A is the chosen solution. This bulkhead replacement will be approximately 175 feet long. The new bulkhead will protect the residence and the drainfield. The Project will include the removal of the creosote timbers that are in the waterway, creating a net gain of ecological function. Conclusions The 175-foot-long, 7-foot-tall existing concrete bulkhead is deteriorating,which will lead to problems with its structural integrity—eventually,total failure will occur. The residence is 7.4 feet from the top of the bulkhead and the septic drainfield is within a few feet of the top of the bulkhead. It is our opinion that the bulkhead should be replaced to protect the residence and septic drainfield before total bulkhead failure. If total failure occurs,the residence would be at immediate risk of falling into the water in less than 3 years, and more likely within weeks to months. To provide structural integrity to the residence,we recommend an anchored, soldier pile wall with precast concrete panel lagging. The existing bulkhead can be removed after installation of the piles and concrete lagging for the new bulkhead.After the old bulkhead is removed,the anchors should be installed immediately. This will not expose the uplands to increased risks from erosion,provided the recommendations below are incorporated into the design. Recommendations For design of the new soldier-pile bulkhead,we recommend assuming the active lateral earth pressure acting on the bulkhead is equal to an equivalent fluid density of 36 pounds per cubic foot (pcf)represented as a triangular distribution against the back of the wall. Active earth pressures should be applied over the full height of the wall accounting for the maximum long-term exposed height of the wall. We recommend a maximum long-term exposed height of 10 feet to account for future beach scour. The ultimate passive earth pressure for the soldier piles extending below the long-term exposed height of the wall and below the beach surface should be 200 pcf. The bulkhead should be designed to be permeable; it will allow a more natural hydraulic connection between the shoreline and the Site. The active earth pressures act over the full soldier pile center-to-center spacing above the base of the bulkhead and over the soldier pile diameter below the base of the wall. Passive pressures act over three times the soldier pile width. The passive values are ultimate values, and we recommend applying a factor of safety of at least 1.5 for design. We also recommend neglecting passive resistance to a depth of 3 feet below the current beach surface. Due to the low retained height of the bulkhead, and because the bulkhead will not provide direct support to a habitable structure,we do not recommend designing the soldier pile bulkhead for surcharge loads from the residence foundations or seismic earth pressures. Page 11 Nye Tides LLC August 17,2022 Project No. 220371-A-01 We recommend that operating equipment and material stockpiles(both temporary during construction and permanent post-construction)should be located at least 8 feet away(laterally) from the back of the wall. If equipment and material stockpiles are to be located closer than 8 feet from the back of the wall,an appropriate surcharge load should be added to the earth pressures provided above. The surcharge load should be distributed uniformly against the back of the wall over the full exposed height. Concrete Panel Lagging For the design of the pre-cast concrete panel lagging,we recommend assuming the pressures exerted on the lagging are equal to 100 percent of the active earth pressures presented above(i.e., no reduction due to soil arching).This is due to a combination of the fill and native deposits that will be present behind the lagging and the use of relatively stiff/rigid lagging material,which reduce the effects of soil arching. We recommend the lagging extend a minimum of 3 feet below the beach surface for long-term support and to account for potential future beach scour. Spacers should be provided between the concrete lagging to ensure adequate drainage through the face of the bulkhead. Earth Anchor Capacities MANTA RAY®(MR)anchors are driven anchor elements installed into the ground by hydraulic or pneumatic equipment without digging,drilling,or concrete backfill/grouting. During driving of the anchors,the surrounding soil is compacted and densified. Once driven to the appropriate depth,the anchors are tensioned in order to lock the bearing plate into position against the surrounding soil, allowing the anchors to rely on the passive earth pressure resistance against the bearing plate to resist pullout and tensile forces on the anchor. The earth anchor capacities are dependent on the soil conditions,the depth of installation,and the size of the anchor bearing plate. For the lateral earth pressures described above,we recommend appropriately sized anchors installed a minimum of approximately 10 feet behind the face of the bulkhead with an inclination of about 15 degrees below horizontal. For the above anchor type and geometry and soil conditions behind the bulkhead,an allowable anchor capacity of 8 kips can be assumed(includes a factor of safety of 2.0). Drainage We recommend a geosynthetic filter fabric be included along the back of the lagging to prevent piping of upland soil through the new bulkhead. The residence and garage do not have roof gutters attached to downspouts. We recommend installation of gutters and downspouts into a tightline that discharges through the face of the new bulkhead. Plans Review We reviewed the design report and plans prepared by Sealevel dated July 20,2022(Sealevel, 2022). Based this review,we understand the bulkhead will consist of a soldier pile wall about 175 feet in length with an exposed height of about 7 to 9 feet and about 3 feet of embedment below the shoreline surface. The lagging for the walls will be constructed using 5-foot-long,pre-cast concrete panels. Page 12 Nye Tides LLC August 17,2022 Project No. 220371-A-0I The soldier piles will be installed landward of the existing bulkhead,about 2 feet behind the face of the existing bulkhead and will be about 9 to 11 feet below the shoreline and about 7 to 9 feet of stickup above the shoreline surface. This will move the bulkhead landward while keeping a similar height as the existing bulkhead. The piles will consist of W6x20,galvanized, steel beams installed with 5-foot-on-center spacing. The concrete panels will be 5 feet long by 2 feet tall by 4 inches thick and a geosynthetic filter fabric will be included along the back of the lagging to prevent piping of upland soil through the new bulkhead. The earth anchors will be 3/4-inch-diameter,threaded, galvanized, MR-1 earth anchors installed with a 15-degree batter and will extend about 10 feet back into the soil behind the bulkhead. The anchors will be installed on a 10-foot spacing for a total of 20 anchors. Channel steel will be affixed to the face the bulkhead and act as a waler for anchorage to the new earth anchors. Based on our review,the plans generally meet our geotechnical recommendations contained herein. Construction Monitoring Aspect should be involved during construction of the new soldier pile wall bulkhead and during the removal of the existing bulkhead.The integrity of the new bulkhead and overall Site stability depend on proper Site preparation and construction procedures. In addition, engineering decisions may have to be made in the field if variations in subsurface conditions become apparent. We recommend a pre-construction meeting be organized at the start of construction that includes you, your contractor,and Aspect. During this meeting,we will gain an understanding of the goals and schedule to be upheld during construction. References ASTM International(ASTM),2018,2018 Annual Book of ASTM Standards, West Conshohocken, Pennsylvania. Google,2022,Google Earth Pro Program,Years reviewed: 6/1994, 11/2003, 7/2005,4/2006, 5/2009,9/2009, 8/2011, 9/2011, 5/2013,2/2015, 8/2016,6/2017, 7/2018,and 6/2021, accessed July 25,2022. Mason County(County),2022, Mason County WA GIS Map,https:Hgis.co.mason.wa.us/mason/, accessed July 25,2022. National Oceanic and Atmospheric Administration(NOAA), 2003,Datums for 9445958, Bremerton,WA,https://tidesandcurrents.noaa.gov/stationhome.html?id=9445958, accessed July 29,2022. Nationwide Environmental Title Research,LLC(NETR),2022, Historical Aerials,Years reviewed: 1951,1980,and 1981,https://www.historicaerials.com/,accessed July 25,2022. Polenz,M.,B.A. Miller,N. Davies, B.B. Perry,K.P. Clark,T.J. Walsh,R.J. Carson,and J.F. Hughes(Polenz et al.),2012,Geologic Map of the Hoodsport 7.5-minute Quadrangle, Mason County, Washington, Washington State Department of Natural Resources, Washington Division of Geology and Earth Resources,Open File Report 2011-3, Scale: 1:24,00,August 2012. Page 13 Nye Tides LLC August 17,2022 Project No. 220371-A-01 Sealevel Bulkhead Builders,Inc.(Sealevel), 2022,Daniel Nye/Nye Tides LLC,Project: Replace failing concrete bulkhead with a concrete soldier pile bulkhead,Drawing 1/2 and 2/2,June 29,2022,report July 20,2022. Tides,2021,Union,Union Tide Chart for July 25,2022, https://www.tides.net/washington/2847/?year=2022&month=7&day=25,accessed July 15, 2022. Washington State Department of Ecology(Ecology),2003, Washington State Coastal Atlas Map, https://fortress.wa.gov/ecy/coastalatlas/tools/Map.aspx, Scale 1:24,000,accessed July 25, 2022. Washington State Department of Ecology(Ecology),2022,Coastal Zone Atlas of Washington, Shoreline Photos from July 24,2016,July 21,2006,May 22,2001, May 24, 1992,June 25, 1977, and 1944, available at: https://fortress.wa.gov/ecy/coastalatlas/,accessed July 5, 2022. Washington State Department of Natural Resources(DNR),2019,Washington Lidar Portal,Hood Canal 2015 DTM Hillshade;Olympics 2017 DTM Hillshade; and Olympics South Opsw 2019 DTM Hillshade,lidarportal.dnr.wa.gov,accessed September 18,2020. Limitations Work for this project was performed for Nye Tides LLC,and this report was prepared consistent with recognized standards of professionals in the same locality and involving similar conditions,at the time the work was performed.No other warranty,expressed or implied, is made by Aspect Consulting,LLC(Aspect). Recommendations presented herein are based on our interpretation of site conditions, geotechnical engineering calculations,and judgment in accordance with our mutually agreed-upon scope of work. Our recommendations are unique and specific to the project,site,and Client. Application of this report for any purpose other than the project should be done only after consultation with Aspect. Variations may exist between the soil and groundwater conditions reported and those actually underlying the site. The nature and extent of such soil variations may change over time and may not be evident before construction begins. If any soil conditions are encountered at the site that are different from those described in this report,Aspect should be notified immediately to review the applicability of our recommendations. Risks are inherent with any site involving slopes and no recommendations, geologic analysis,or engineering design can assure slope stability. Our observations,findings,and opinions are a means to identify and reduce the inherent risks to the Client. It is the Client's responsibility to see that all parties to this project, including the designer, contractor,subcontractors,and agents,are made aware of this report in its entirety. If project developments result in changes from the preliminary project information,Aspect should be contacted to determine if our recommendations contained in this report should be revised and/or expanded upon. Page 14 Nye Tides LLC August 17,2022 Project No.220371-A-01 The scope of work does not include services related to construction safety precautions. Site safety is typically the responsibility of the contractor,and our recommendations are not intended to direct the contractor's site safety methods,techniques,sequences,or procedures.The scope of our work also does not include the assessment of environmental characteristics,particularly those involving potentially hazardous substances in soil or groundwater. All reports prepared by Aspect for the Client apply only to the services described in the Agreement(s)with the Client.Any use or reuse by any party other than the Client is at the sole risk of that party,and without liability to Aspect. Aspect's original files/reports shall govern in the event of any dispute regarding the content of electronic documents furnished to others. Please refer to Appendix A titled "Report Limitations and Guidelines for Use" for additional information governing the use of this report. We appreciate the opportunity to perfonn these services. Sincerely, Aspect consulting, LLc of Was/7/ CO y En ' eering Geologist 271633194��0 �SOd Geoff° 8/17/2022 FS CASTE �G� 8/17/2022 srUNAL� F- Alison J. Dennison Alison I Dennison,LEG Henry H. Haselton,PE,PMP Senior Engineering Geologist Principal Geotechnical Engineer adennison@aspectconsulting.com hhaselton@aspectconsulting.com Attachments: Appendix A—Report Limitations and Guidelines for Use VA220371 Nye Tides Shoreline\Deliverables\Geotechnical Assessment—Nye Tides Bulkhead.docx Page 15 APPENDIX A Report Limitations and Guidelines for Use ASPECT CONSULTING REPORT LIMITATIONS AND GUIDELINES FOR USE Geoscience is Not Exact The geoscience practices(geotechnical engineering,geology,and environmental science)are far less exact than other engineering and natural science disciplines. It is important to recognize this limitation in evaluating the content of the report. If you are unclear how these 'Report Limitations and Guidelines for Use" apply to your project or property,you should contact Aspect Consulting, LLC(Aspect). This Report and Project-Specific Factors Aspect's services are designed to meet the specific needs of our clients. Aspect has performed the services in general accordance with our agreement(the Agreement)with the Client(defined under the Limitations section of this project's work product). This report has been prepared for the exclusive use of the Client. This report should not be applied for any purpose or project except the purpose described in the Agreement. Aspect considered many unique,project-specific factors when establishing the Scope of Work for this project and report. You should not rely on this report if it was: • Not prepared for you; • Not prepared for the specific purpose identified in the Agreement; • Not prepared for the specific subject property assessed; or • Completed before important changes occurred concerning the subject property,project,or governmental regulatory actions. If changes are made to the project or subject property after the date of this report,Aspect should be retained to assess the impact of the changes with respect to the conclusions contained in the report. Reliance Conditions for Third Parties This report was prepared for the exclusive use of the Client.No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against liability claims by third parties with whom there would otherwise be no contractual limitations. Within the limitations of scope,schedule,and budget, our services have been executed in accordance with our Agreement with the Client and recognized geoscience practices in the same locality and involving similar conditions at the time this report was prepared. Property Conditions Change Over Time This report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time,by events such as a change in property use or occupancy, or by natural events, such as floods, earthquakes, slope instability,or groundwater fluctuations. If any of the described events may have occurred following the issuance ASPECT CONSULTING of the report,you should contact Aspect so that we may evaluate whether changed conditions affect the continued reliability or applicability of our conclusions and recommendations. Geotechnical, Geologic, and Environmental Reports Are Not Interchangeable The equipment,techniques,and personnel used to perform a geotechnical or geologic study differ significantly from those used to perform an environmental study and vice versa. For that reason,a geotechnical engineering or geologic report does not usually address any environmental findings, conclusions, or recommendations(e.g., about the likelihood of encountering underground storage tanks or regulated contaminants). Similarly,environmental reports are not used to address geotechnical or geologic concerns regarding the subject property. We appreciate the opportunity to perform these services. If you have any questions,please contact the Aspect Project Manager for this project.