DELIVERABLES FOR TASK NO: 4 Shannon Point Riprap Removal Feasibility Study and 60% Project Design

Transcription

1 County: Skagit County Grant No: G PROJECT TITLE: Northwest Straits Project: Skagit County Marine Resources Committee Operations and Projects DELIVERABLES FOR TASK NO: 4 Shannon Point Riprap Removal Feasibility Study and 60% Project Design PROGRESS REPORT: [] PROJECT FINAL REPORT: [X] PERIOD COVERED: September 16 January 31, 2014 DATE SUBMITTED: February 25, 2014 This project has been funded wholly or in part by the United States Environmental Protection Agency. The contents of this document do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

2 Shannon Point Revetment Removal Feasibility and Preliminary Design Report, Anacortes, Skagit County, WA Prepared for: The Northwest Straits Marine Conservation Foundation Prepared by: Coastal Geologic Services, Inc. Preparers: Jim Johannessen, Stephanie Williams, Jonathan Waggoner, and Alexis Blue Jan. 12, 2013

3 COASTAL GEOLOGIC SERVICES, INC. Table of Contents Introduction and Purpose... 1 Site Conditions... 1 Overview... 1 Geology of Bluffs... 2 Beach... 2 Coastal Processes... 3 Rock Revetment... 4 Wetland... 5 Marine Riparian Vegetation... 5 Documented Forage Fish Spawning Areas... 6 Site History... 7 Preliminary Design Alternatives... 7 Alternative 1: Full Restoration... 8 Alternative 2: Full Rock Revetment Removal... 8 Alternative 3: Partial Rock Revetment Removal... 9 No Action: Existing Conditions... 9 Phasing... 9 Conclusions and Recommendations Preferred Alternative Constraints Benefits Slope Stability Assessment for Preferred Alternative Integration of Previous Geology/Stability Work Geology and Stratigraphy Bluff Configuration Location and Elevation of Bluff Toe House Setback to Top of Bluff Implementation Considerations and Analysis Removal by Truck Overland Removal by Barge Rock Reuse Preferred Alternative Cost Estimate Limitations of This Report References ATTACHMENTS: APPENDIX A: Ellis St. Suite 103, Bellingham, WA (360) www@coastalgeo.com

4 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 1 COASTAL GEOLOGIC SERVICES, INC. Introduction and Purpose The purpose of this technical memorandum is to document the site conditions and major project considerations of a potential rock revetment removal along a portion of shore on the southwest shore of Shannon Point within the water body of Rosario Strait just south of Bellingham Channel, in Skagit County, Washington (Figure 1). The site consists of an undeveloped wooded parcel owned by Western Washington University (WWU) and beach, which is largely in City of Anacortes ownership. Coastal Geologic Services (CGS) staff visited the site several times in 2013, including for a site assessment and topographic survey on May 28 th and 29 th, when there was a low tide of 2.4 ft Mean Lower Low Water (MLLW). We conducted an additional site on December 31, 2013 to assess slope stability of the upland development southeast of the southern portion of the causeway. The northwest Straits Foundation requested that CGS complete a topographic survey and feasibility assessment, followed by development of an engineered design for the maximum amount of process and habitat nearshore restoration possible without causing negative impacts to adjacent landowners. This report describes site conditions, determine whether removal of the rock revetment and parts of the railroad causeway fill is feasible, the benefits these actions would result in, and, how and to what extent the removal could be accomplished. The report provides 3 habitat restoration alternatives, and provides an overview of the feasible, preferred alternative. This design has been advanced to the 60% design level with 2 drawing sets attached; one larger format set which will be developed into final construction drawings in the next phase, and a smaller format set for permitting with the US Army Corp of Engineers (USACE). An updated construction cost estimate is also provided. Overview Site Conditions The old railroad causeway is comprised of a 6 to 19 ft high bank from north to south, some of which appears to be native material and some of which is fill added to build up the railroad causeway. The rock revetment spans 766 ft along shore from a bedrock headland at the south end of the site. The causeway and fronting riprap revetment extends across the upper beach to +4.2 ft MLLW. The north end of the causeway and revetment extends down to local Mean Higher High Water (MHHW) for the Shannon Point vicinity, which is +8.0 ft MLLW (NOAA). A local trail runs north along the causeway from a nearby residential street. The houses in the vicinity are built on the native bluff and bedrock. The WWU Shannon Point Marine Center is north of the site. A small wetland exists landward of the filled causeway and rock revetment. All of these elements contribute to the feasibility of the rock revetment removal and will be further explored in the following text.

5 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 2 COASTAL GEOLOGIC SERVICES, INC. Geology of Bluffs The site consists of bedrock and glacial and nonglacial deposits from the Pleistocene period. The Pleistocene deposits were observed in the field as glacial till from the Vashon Stade (Qgt) underlain by nonglacial Olympia beds (Qc(o)) or Whidbey Formation (Qc(w)). Vashon till (also referred to as glacial till) is an unsorted mix of clay, silt, sand, and boulder sized clasts ranging from sub angular to rounded. Till outcrops in thin veneers over bedrock (Lapen 2000) and become thicker going north. This unit was the dominant material in the bluffs near the project area (Photo Pages 1 and 2), which is consistent with Washington Department of Natural Resources (DNR 2010) 1:100,000 maps of the area as compiled from geologic mapping of the Bellingham Quadrangle (Lapen 2000) (Figure 2). The likely nonglacial unit underlying the till is a silty sand with localized cross bedding and sandy pebble lenses, as well as peat observed on the beach face (Photo Page 2). This unit was observed from beach level up to +8 ft MLLW at the north end of the site and extended higher up the bluff face farther north towards Shannon Point. The contact between the glacial till and the nonglacial units was undulating. The likely nonglacial unit or units are not included in the 1:100,000 digital GIS mapping, but are mapped nearby in the higher resolution 1:24,000 geologic mapping of the Anacortes South and LaConner (Dragovich et al. 2000) and Oak Harbor (Dragovich et al. 2005) quadrangles. In these maps the Olympia beds are described as nonglacial deposits composed of sand, gravelly sand, organic rich sand, silty sand, silt, silty clay, and peat with lesser cobble gravel and gravel; peat logs are common; may locally include outwash sand of the Possession Glaciation and nonglacial sediments of the older Whidbey Formation (Dragovich et al. 2000). The Whidbey formation is described as silt, clay, peat, silty sand, sand, and rare pebbly sand displaying a variety of fluvial characteristics (Dragovich et al. 2005). Exposed bedrock in the project area was confined to the south end where it outcrops as a rocky headland and underlies much of the area to the south of this point. Geologic mapping indicates that bedrock is present from the exposed outcrops at the site to the south and west of Fidalgo Island (DNR 2010, Lapen 2000) (Figure 2).The bedrock is mapped as ultramafic rocks of the Fidalgo ophiolite Ju(f) and described as serpentinite, harzburgite, and lesser olivine chromitite layers, with cross cutting veins of pyroxenite throughout an ultramafic body. Gravity studies indicate this unit is a nearly horizontal slab like body 1 km thick (Carlson 1972). This is consistent with observations made during the site visit, however, without subsurface exploration the depth to the bedrock is unknown. Beach The beach at the site is comprised of mainly cobble and small boulder along the beachface down to a low tide terrace, with pebble and sand along the upper beach (Photo Page 2). The cobble and small boulder is primarily composed of native ultramafic bedrock, especially on the south end near the bedrock headland. Large boulders are scattered throughout the beachface and into the low tide terrace. A sandy beach with suitable forage fish spawning substrate exists just north of the bedrock headland resembling a small pocket beach in plan view (Photo Page 2 and Figure 3). It is likely that the rock

6 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 3 COASTAL GEOLOGIC SERVICES, INC. revetment is covering native upper beach and significantly limited available suitable forage fish spawning habitat. Beyond the low tide terrace is a sandy tide flat with eelgrass, the landward extent of which was surveyed during the site visit. Coastal Processes Coastal processes at this site are influenced by the characteristics of the specific drift cell and associated up drift factors, including geology and stratigraphy, shore orientation and subsequent exposure to wind generated waves. The site is exposed to a fetch (distance over which windgenerated waves are formed) from the northwest, measuring 9.7 miles to Orcas Island directly across Rosario Strait. This is a moderate to high fetch. From the south quadrant, the prevailing and predominant wind direction, the site is largely sheltered by a series of bedrock headlands on north Fidalgo Island, including the headland immediately south of the site. Therefore, fetch from the south is negligible. The beach at the site is part of a larger coastal system that is defined by net shore drift cells. Net shore drift refers to the long term effect of coastal processes in the form of discrete coastal sediment littoral transport systems as mapped by Schwartz et al. (1991) and Johannessen (1992). A net shoredrift cell extends from the beginning of a sediment source to a sediment sink or depositional area (Johannessen and MacLennan 2007). Bluff sediment input, primarily loose to moderately compact glacial and interglacial deposit units, are the primary source of beach sediment in Puget Sound region (Keuler 1988). Drift cell SK D 2 originates 2,000 ft south of the site at Washington Park and extends northward around Shannon Point to the ferry landing (Figure 1). The site is located within the first third of the drift cell. Current and historic geomorphic shoretypes of north Fidalgo Island were identified and mapped for Skagit County by MacLennan and Johannessen (2008) and recently compiled into the Puget Soundwide data set of geomorphic shoretypes for the Department of Ecology (MacLennan et al. 2013). This mapping takes into account the geomorphic shoretype in the context of the net shore drift system. The rock revetment at the site was mapped as modified and as a likely historic feeder bluff prior to development. To the north of the site and down drift of the armored shore, feeder bluffs are mapped around Shannon Point to Cannery Lake extending nearly 2,300 ft. The configuration of the bedrock headland at the southern end of the project area likely contributes to the sandy beach at the site. The predominantly southwesterly waves tend to be refracted by the headland to break parallel to shore resulting in a very low sediment transport potential and retention of fine sediment. In contrast, waves tend to approach the northern portion of the project area at an oblique angle, tending toward higher sediment transport potential. This likely results in the gradual transport of sand out of the system, leaving coarser sediment behind. This is particularly true as the causeway has blocked input of bluff sediment from the former feeder bluffs in the study area. Other geomorphic shoreline mapping conducted for Puget Sound Nearshore Ecosystem Restoration Project (PSNERP) takes into account coastal landforms independent of the net shore drift system. This

7 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 4 COASTAL GEOLOGIC SERVICES, INC. mapping identified the site as a rocky platform transitioning to a bluff backed beach that continues north around Shannon Point to Cannery Lake (Simenstad et al. 2011). Rock Revetment The existing rock revetment was surveyed on May 28 th and 29 th. Existing conditions are presented in the CADD sheet sets in Appendix A. The rock revetment appears to have been constructed of two courses. The first, lower course consists of apparently local native bedrock boulders, averaging 1 3 ft in size. Angular granite rock averaging 3 6 ft in size was placed atop the lower course, likely at a later date. The revetment varied in condition from relatively undamaged at the southern end to completely destroyed portions to the north. The rock revetment was split into sections 1 through 7 for the purposes of describing the revetment and quantifying the rock. The sections were split at natural breaks between reaches of the rock revetment with similar character or dimensions. The character of the rock in the sections and section breaks are shown in Photo Page 3 and Figure 3, respectively. A field assessment of the thickness of rock was made at 23 points along the revetment on May 29, These points were chosen to be representative of specific revetment reaches. These thicknesses were combined with the dimensions measured by the topographic survey to determine crosssectional areas. The cross sectional area and alongshore length of each segment were multiplied to estimate rock volumes. Table 1 summarizes the measurements for each of the 7 revetment sections. Overall, the revetment was estimated to contain 2,512 cubic yards (CY) of rock. Of this, approximately 65% (1,625 CY) consisted of granite, and 35% (875 CY) consisted of native bedrock boulders. No subsurface investigations were made as part of these estimates, so they should be considered preliminary quantities subject to additional refinement through the removal and design process. Table 1. Rock revetment volume estimates by section. See Figure 3 for section locations. Average Rock Alongshore Cross-sectional Section Height (FT) Length (LF) Area (SF) Volume (CY) Total Preliminary investigation at the toe of the rock by Slocum (2011) indicated that the rock was originally placed on the existing ground surface and was not buried. Slocum also noted that drifting sand had

8 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 5 COASTAL GEOLOGIC SERVICES, INC. accumulated to a depth of about a foot at the toe of the revetment in some places, but that the toe did not appear to be deliberately buried (Slocum 2011). Causeway fill material likely consists of local glacial till, nonglacial deposits, native bedrock boulders, and quarry spall. In some areas it appears that imported granitic rock quarry spall was placed near the top of the causeway, possibly to repair or fill areas of the originally constructed causeway (Photo Page 4 and 5). Portions of the causeway were likely cut from the native bluff and that material was used to fill other parts of the causeway. Based on the field observations, GPS points were collected to map where the causeway likely cut into the bluff and where the causeway was likely filled. These are shown on Figure 3 and labeled as native bluff. In the vicinity of the wetland the causeway contains large 1 3 ft native bedrock boulders as fill, as shown in Photo Page 5. The far southern end of the causeway fill may contain more rock as it is adjacent to the cut through bedrock from the south. Exploration into the subsurface materials in these locations was conducted through shallow test pit excavations to determine the character of sediments. Shallow test pits were dug in specific locations of the causeway suspected as having been filled and also two locations behind the causeway (Figure 3). The sediments were described to the best professional judgment of the geologist and are considered the best available information in lieu of larger drilling or excavating equipment, such as a backhoe, which could not be brought to the site due to access and budget limitations (Table 2; Photo Pages 4 and 5). Wetland A wetland is located landward of the sandy beach area and rock revetment at the site. It has been classified by Aqua Terr Systems, Inc. (ATSI 2012) as an approximately 1,400 square foot Category III depressional closed permanently flooded (PEMH) forested wetland. ASTI judged that the wetland had a habitat score of 15. Please refer to the ASTI report for more information. It was recommended by ATSI that a critical areas report be conducted in late spring and the dry season to verify hydrologic regimes and vegetation during alternate seasons. During the May 2013 site visits the wetland was holding water. The north and south ends of the oblong wetland paralleling the backside of the causeway were marked with GPS (Figure 3). Since the potential restoration actions would result in substantial overall habitat improvement, a critical areas report may not be needed. Marine Riparian Vegetation The vegetation adjacent to the shoreline was described by ATSI as forested canopy with understory shrubs and herbaceous vegetation. Vegetation at the site includes Douglas fir (Pseudotsuga menziesii), red alder (Alnus rubra), grand fir (Abies grandis), western red cedar (Thuga plicata), and madrone trees (Arbutus menziesii); elderberry (Sambucus racemosa), snowberry (Symphoricarpos albus), osoberry (also known as Indian plum) (Oemleria cerasiformis), Nootka rose (Rosa nutkana), red huckleberry (Vaccinium parvifolium), thimbleberry (Rubus parviflorus), and salmonberry (Rubus spectabilis) shrubs; and sword fern (Polustichum munitum), salal (Gaultheria shallon), herbaceous native and non native grasses, vetch, and spring flowers groundcover plants. ATSI reported

9 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 6 COASTAL GEOLOGIC SERVICES, INC. approximately 50 trees 8 20 inches diameter at breast height (DBH) were present along the crest of the rock revetment. Table 2. Test pits excavated for materials observation. Depths reported in below ground surface (BGS) inches. Test Pit # Depth (BGS) Observation TP 1 causeway TP 2 causeway TP 3 causeway TP 4 causeway TP 5 depression TP 6 depression TP 7 causeway TP 8 causeway TP 9 causeway TP 10 causeway 6 inches 5 inches below causeway crest, in scarp on waterward side. Angular native bedrock 4-12 inches diameter and smaller resembling quarry spall/fill, in silty matrix. Likely native fill. 8 inches 1.5 ft below causeway crest on waterward side. Angular granitic rock 6-12 inches diameter and smaller, in silty matrix. Likely native and imported fill. 8 inches 8 ft below causeway crest on landward side. Medium to coarse orange sand with few fines (silt) and sub-rounded pebbles. Likely native fill inches 10 ft below causeway crest on landward side (near depressional wetlandabout 3 ft above wetland). Silty fine sand with few random sub-angular to sub-rounded pebbles. Medium plasticity indicating fines. Likely native fill inches North end of depression landward of causeway. Fine to medium gray sand, sub-rounded pebbles, pebble lens apparent below 1 ft. Native beach material inches North end of depression landward of causeway. Medium to coarse gray sand, few sub-rounded pebbles and cobbles. Native beach material. 8 inches 5 ft from causeway crest on landward side. Silty with fine sand and few sub-rounded to sub-angular pebbles. Medium plasticity indicating fines. Likely native fill. 6 inches At top of causeway. Sandy silt with few medium sub-rounded pebbles. Likely native fill. 6-8 inches 3 ft from causeway crest on landward side. Angular native bedrock 3-8 inches and smaller, resembling quarry spall, in silty matrix. Likely native fill. 6-8 inches 10 ft from causeway crest on landward side (3 ft above depressional wetland). Silt with few angular clasts, high plasticity. Likely native fill. Documented Forage Fish Spawning Areas Forage fish are important prey sources for Pacific salmon and other species that use the nearshore for spawning in the Puget Sound (Penttila 2007). Surf smelt spawning occurs on the upper intertidal beach and to up just above MHHW. Spawn from surf smelt and Pacific sand lance forage fish have been documented in nearby intertidal areas. Surf smelt spawn have been documented up drift in Washington Park and down drift in the vicinity of the San Juan Islands Ferry landing. Pacific sand lance spawn have been documented down drift of the ferry landing on the beach of Ship Harbor and the associated coastal wetland (WDFW 2004).

10 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 7 COASTAL GEOLOGIC SERVICES, INC. Site History Historic topographic mapping (T sheet) from 1885 is presented in Figure 4, which shows the earliest reliable mapping of predevelopment conditions in the area. From south to north the T sheet shows a rocky headland at the south end of the site, a historic beach and intertidal zone that has since been buried by the railroad causeway, bluffs fronting the beach, and a general coarsening of beach sediment. The railroad causeway was apparently not constructed at this time, as it is not identified on the T sheet. The development of the railroad, causeway, and granite rock revetment was researched and documented by ATSI (2012). The railroad was not shown in an H sheet (#1814) dated 1887, but the 1891 supplemental sheet showed the railroad north of the study site. ATSI (2012) reported that the railroad line was constructed in 1890 in attempt to become the west coast terminus for the transcontinental railroad. The shoreline characteristics shown in the T sheet suggest that the beach area near the current wetland is actually historic beach that has been buried by the railroad causeway. Beach material excavated from test pits 5 and 6 (Table 2), which are located landward of the causeway near the wetland, also suggests that the wetland is actually historic upper beach and backshore that has been partially buried and truncated by the construction of the causeway (Figure 4). Based on the shoreline configuration shown in the T sheet, the observed and mapped native bluff points, and the likely beach sediment found at test pits 5 and 6 (Figure 4), one could surmise that from south to north the original causeway was constructed as follows: The bedrock headland was cut down to grade in the railway alignment, extending northward to approximately towards the native bluff south point. Parts of the southern end of the causeway were likely filled with the cut materials from native bedrock and glacial and nonglacial sediments in the vicinity of the recessed beach (now a depressional wetland). The majority of causeway fill likely came from cutting into the high elevation native glacial and nonglacial bluff within the northern reach of the causeway, at the native bluff north point. Interviews with a local resident indicated that the granite for the rock revetment was placed sometime after the construction of the causeway to protect it, perhaps around 1920, even though the railroad was abandoned at approximately this time, (ATSI 2012). Historic vertical and ground photographs are available; however, since the rock revetment predated the photos, these historic photographs show little change in the shoreline. Preliminary Design Alternatives Restoration alternatives were explored for the project area in an effort to maximize habitat restoration in balance with costs. Three alternatives were developed and are outlined below, along with a brief discussion of the No Action alternative. The three alternatives are shown in Figure 8 and summarized in Table 4.

11 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 8 COASTAL GEOLOGIC SERVICES, INC. Alternative 1: Full Restoration This would entail removal of both the revetment and the entire causeway fill. Rock would first be removed from the revetment and hauled off site by barge or overland. Trees and other vegetation would be removed from the top of the causeway. Trees would be retained on site as large woody debris (LWD) on the upper beach, while some smaller vegetation would be hauled offsite. All filled portions of the causeway would then be removed for off site disposal. The causeway fill appeared to consist of gravelly sand fill, however, a small amount of 1 3 ft size native bedrock was visible in the landward side of the causeway near the wetland, so it is possible that more of this rock is present in the causeway fill. Salt marsh habitat may become established landward of where the causeway fill is removed, in the vicinity of the current wetland. Based on approximations of materials to be removed (Figure 8), around 36,430 ft 2 of beach habitat and up to 4,900 ft 2 of potential salt marsh would be recovered with Alternative 1. Site enhancement elements include revegetation, to be determined upon further design development. Beach nourishment is not necessary at this site due to the quality of the existing sand and gravel beach sediment along with input of sediment from adjacent feeder bluffs which will become available upon removal of the revetment rock and causeway fill. Alternative 2: Full Rock Revetment Removal This alternative includes removal of all revetment rock from the project site, including both imported granitic and native bedrock initially used to protect the causeway. Removal of this rock will expose the causeway, which would likely be eroded rapidly in the first 2 3 years in what is termed deferred erosion. After the initial relatively rapid adjustment to armor removal, the erosion rate is expected to slow, but erosion would continue to re expose the upper beach to a similar bluff toe elevation as is present just north of the revetment (approximately ft MLLW). Leaving the causeway fill in place would provide intermittent sediment input to the beach and drift cell. As the large majority of the fill appears to be derived from local excavations into the nearby bluffs, this sediment will serve as beach nourishment to augment the beach and its potential spawning habitat. Trees at the waterward edge of the causeway and other vegetation will be addressed similar to that described in Alternative 1. However, the majority of trees and vegetation would be left on top of the causeway. Soil under many of these trees would erode over the coming years leading to toppling of many trees, which would provide LWD to the nearshore. Alternative 2 will be far more cost effective than full causeway removal due to the substantially smaller volume of excavation and removal. However, additional fill removal may become necessary where the surface of the causeway fill contains debris not suitable for beach sediment (fill not associated with locally derived glacial and non glacial sediments such as angular rock). Any such angular boulders in the exposed fill surface of the causeway should be excavated following removal of the revetment rock and hauled off site for reuse or disposal. As this alternative would leave the causeway fill to erode and nourish the beach, some amount of boulder would end up on the beach from the fill, particularly in the south end of the site where more rock may be present. The condition

12 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 9 COASTAL GEOLOGIC SERVICES, INC. of the beach should be reviewed approximately 5 years after removal for the potential to remove additional rock from the potential forage fish spawning band. Based on estimated measurements of materials removed (Figure 8), approximately 15,250 ft 2 of beach habitat would be recovered with Alternative 2. Site enhancement elements include those listed in Alternative 1. Alternative 3: Partial Rock Revetment Removal Partial rock revetment removal includes removal of all granitic rock, leaving the native bedrock scattered along the beach or possibly moving native bedrock from the revetment in the south sections onto the rocky headland area composed of the same material. Trees and other vegetation will be dealt with similarly to that described in Alternative 2. The main filled causeway (Figure 3, Sections 1 3) likely contains sufficient native bedrock to continue to armor the toe of the causeway. Erosion here is expected to remain very low. The northern revetment appears to contain primarily granite, and native bedrock was not observed. This would lead to deferred erosion in the northern reach similar to that described in Alternative 2. Based on measurements and estimates of materials removed (Figure 8), approximately 7,330 ft 2 of beach habitat would be recovered with Alternative 3. Depending on the amount of native revetment rock moved to near the rocky headland slightly more habitat area may be recovered under this alternative. Site enhancement elements include those listed in Alternative 1. Benefits and constraints are summarized in Table 3. No Action: Existing Conditions The no action scenario would consist of leaving all parts of the revetment in place and making no changes to existing conditions. Under no action there will be no habitat benefits to the beaches in the vicinity of the site and the beach area would continue to experience negative impacts such as increased wave reflection and hydraulic turbulence, and continued greatly reduced productivity of the intertidal beach (Johannessen and MacLennan 2007). Additionally, the historic feeder bluff (MacLennan and Johannessen 2008) will continue to be disconnected from the net shore drift cell, and no benefits to adjacent beaches would be realized. With no action, the rock revetment will continue to pose a hazard to the public who wish to use the trail for beach access. Also, there is a potential for further beach habitat burial from toppling boulders from the rock revetment. Phasing Phasing of restoration actions is a possibility with Alternatives 1 and 2. For instance, Alternative 2 could act as a precursor to the full removable of the causeway fill (Alternative 1). While allowing for limited funding to be utilized over the course of a multi phase approach, the phasing approach is often more expensive because mobilization costs are doubled. Therefore, carrying out Alternative 2 is

13 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 10 COASTAL GEOLOGIC SERVICES, INC. recommended. Even if minor beach cleanup is required approximately 5 years after armor removal, this would still be far less expensive in total than carrying out Alternative 1. Table 3. Restoration alternatives summary for the project area at Shannon Point. Restoration Alternatives 1 - Full Restoration 2 - Full Rock Removal 3 - Partial Rock Removal Habitat Benefits Project Constraints Relative Cost Recovery of ~36,430 ft 2 of beach/intertidal habitat Recovery of up to ~4,900 ft 2 of potential salt marsh Increased potential forage fish spawning area Increased bluff sediment input downdrift beaches and forage fish spawning beaches Recovery of ~15,250 ft 2 of beach/intertidal habitat, increasing over time Fresh marsh transition to salt marsh Increased potential forage fish spawning area Erosion of sandy sediment from causeway and bluff will benefit downdrift beaches Recovery of approximately 7,330 ft 2 of beach/intertidal habitat, mainly at the south end of the site Limited erosion of sandy sediment from causeway will benefit down-drift beaches High cost, many round trips; less sediment for the beach Barge access will require clearing boulders from larger beach areas Removal by truck will require more vegetation removal, potential temporary causeway upgrades, and more disturbance to neighbors Barge access will require clearing boulders from larger beach areas Barge access or removal by truck similar to Alt 1 Leaves rock on the beach with less habitat benefit Barge access or removal by truck similar to Alt 1 Highest: Greater than estimates given for Alt 2, more time and more material to remove Moderate: $314,094 removal by truck (removal only; pretax) $100,000 plusremoval by barge (removal only, before tax) Lowest: Less expensive than estimates given for Alt 2 Conclusions and Recommendations Preferred Alternative Alternative 2 is the preferred alternative as it was determined to be both feasible and provides the most restoration benefit with the least constraints, as well as a relatively moderate cost. This alternative would remove a far smaller amount of material as compared to Alternative 1, full removal, and would be far less expensive. Removal of only the granite rock (Alternative 3) is not recommended as a significant amount of armor and infringement on potential forage fish habitat would remain. All of the revetment rock would be removed in Alternative 1 along with likely removal of small quantities of imported fill or native bedrock boulders apparent in the surface of the causeway fill. This material would likely be removed by barge, as initial cost estimates suggest barge removal would be a

14 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 11 COASTAL GEOLOGIC SERVICES, INC. significant cost savings and less upland disturbance over truck removal. Project planning should include acquiring firm bids from reputable contractors prior to a final decision on removal method. Alternative 2 would result in a large, immediate gain of upper beach habitat through direct removal of all of the revetment rock on site. Additionally, causeway fill would nourish the beach and drift cell over time, enlarging the beach area through erosion of high elevation fill and also the deposition of this sediment. Causeway fill would provide a short to medium term sediment source to the drift cell as it is eroded by wave action. Over approximately 5 years or less, most of the fill is expected to be eroded, restoring the upper intertidal and adjacent, narrow backshore areas. This will also likely result in landward sediment transport in part of the current small, closed freshwater. This wetland is only present now due to the causeway, as no feature was mapped in the T sheet and this is an unlikely location for such a feature naturally. Constraints and benefits of the preferred alternative are outlined first below, followed by a detailed evaluation of these constraints, which are the key factor to determine if the benefits can be realized on the ground. Constraints Stability of three parcels at the south end of the revetment (parcels P117670, parcel P117669, parcel P117668) are further assessed from slope stability under the recommended revetment rock removal and subsequent erosion of the causeway fill of the preferred alternative. Other parcels in the vicinity are either built on bedrock, or do not appear to be impacted by the proposed actions. Access and method of removal, whether by truck overland or by barge is described more thoroughly below. It appears that removal by barge may be lower cost and lower impact to neighbors. Cost of the project is a major consideration. For the length of shore restored, the balance between cost and habitat benefit appears favorable. Parcel owners within the proposed removal area, Western Washington University and the City of Anacortes (Figure 6), are willing project partners at this stage and do not appear to be constraints. Benefits The site presents a very good opportunity for nearshore habitat restoration. This restoration opportunity was identified as a priority within drift cell SK D 2 (MacLennan and Johannessen 2008) based on the extent of beach burial (southern end of revetment was estimated to +4.2 ft MHHW), potential forage fish spawning habitat, and length of shore/volume of sediment to re enter the drift cell. The bulkhead at the site appears unnecessary as it was originally constructed to protect a cut and filled causeway in the late 1800 s with additional rock added in the 1920 s. The shore modifications appear to have covered a moderate amount of upper beach habitat and created a barrier between

15 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 12 COASTAL GEOLOGIC SERVICES, INC. the historic bank and upper beach and coastal waters. Restoration recommendations provided in this feasibility assessment are generally consistent with those found in the Management Measures report created to provide guidance for conceptualizing and designing nearshore restoration projects in Puget Sound (Clancy at al. 2009). Management Measure 1: Armor Removal, is beneficial by providing the following: Improved connectivity between upland and littoral drift processes Restoring sediment transport processes and shoreform diversity Increasing shoreline resilience in the face of projected sea level rise Restoring a valued ecosystem component that would in turn directly benefit salmon, forage fish, clams, and eelgrass Social and political benefits including improved aesthetic and recreational values. See discussion of Alternative 2 and Preferred Alternative above for specific project benefits. Slope Stability Assessment for Preferred Alternative Slope stability of the bluffs landward of the southern portion of the rock revetment and causeway are more thoroughly discussed in this section to discern if proposed revetment removal actions could further destabilize slopes and pose a threat to the houses. The slopes in this vicinity are documented as stable by the Department of Ecology Coastal Zone Atlas (Ecology 1979; Figure 5), however evidence of slope instability was present during the field visits. Property ownership in the vicinity of the project area has been researched through the Skagit County Assessor, shown in Figure 6, and includes nearby properties of the Sunset Cove development which are the subject of this slope stability investigation. Integration of Previous Geology/Stability Work Geotechnical reports were obtained from the City of Anacortes to further explore previously documented conditions relating to slope stability of the uplands at this location. The preliminary geotechnical engineering report for Sunset Cove Project (subdivision development in Anacortes) produced by Associated Earth Sciences, Inc. (AES 1992) had the most relevant information for the area in question. AES found very low and low landslide hazards along the northern boundary of the Sunset Cove development prior to development based on the geologic unit (lodgement till) and slopes. Subsurface geology was explored by AES at 5 exploration pits, 2 of which are on the north end of the development and within the area of further slope stability exploration. Exploration pits EP 3 and EP 5 were recorded by AES as topsoil overlying glacial outwash and till at relatively shallow depths, both reaching interpreted lodgement till at approximately 7 ft below ground surface (Table 4 for data log; Figure 7 for location map). AES (1992) had recommended house setbacks of at least 25 ft from top of slope where slopes were 40 percent or greater as part of landslide mitigation. The sediment description from the subsurface exploration by AES shows till extending 50 ft farther west than was mapped by DNR at 1:100,000 (coarse) scale mapping. Other than simply a scale of mapping issue for the WDNR data, this discrepancy is likely due to the tendency of lodgement till to

16 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 13 COASTAL GEOLOGIC SERVICES, INC. Table 4. AES (1992) exploration pit logs at EP 3 and EP 5 and record of subsurface sediments. be deposited directly over other geologic units, as the bedrock can be very clearly observed in lower elevations in the vicinity of the house at parcel P where EP 5 was located. It is very possible that lodgement till overlies some portions of bedrock at this location. Moving east from this location

17 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 14 COASTAL GEOLOGIC SERVICES, INC. along the bluff both the AES report and DNR mapping concur on the presence of glacial (or lodgement) till with a shallow cap of glacial outwash. Field reconnaissance visits with additional topographic survey were conducted by CGS to assess the existing slope stability of the bluff properties landward of the revetment removal area. This investigation included three parcels (from west to east) P117670, P117669, and P (Figure 6). Several factors were assessed to discern the existing slope stability and to give an objective account of whether the proposed revetment removal actions would cause greater slope instability in this area. The following factors directly affecting slope stability conclusions for this determination, and are discussed below: Geology and stratigraphy Bluff configuration Location and elevation of the (original) bluff toe House setback to top of bluff Geology and Stratigraphy Surface geology mapped by DNR for the subject investigation area (as outlined in Geology of Bluffs section above) documented bedrock at parcel P and till underlying parcels P and P Explorations by AES found till underlying at parcel P117670, but the till likely overlies the bedrock in this location. Bedrock slopes are generally stable, provided that intersections of slope and bedding or slope and fracture planes at an adverse orientation are not prevalent (Easterbrook 1976), which is not observed in this native bedrock. Therefore the stability of structures built over this native bedrock will not be affected following potential exposure of the bank toe and will not be endangered by removal of the rock revetment. The stratigraphy of the bluffs at parcels P and P117668, as documented and observed during field reconnaissance, are composed of glacial till possibly overlying sands and silts of the Whidbey Formation at an unknown depth. This Whidbey Formation sequence has inherent weaknesses under present conditions. Several saturated slump blocks and seeps were apparent toward the lower 1/3 of the bluff at parcel P This condition would not be changed by potential revetment removal. Bluff Configuration To further assess the bluff conditions of these properties, cross sections (Profiles A and B) were generated along the slope from LiDAR elevation contours and corrected with on site survey measurements where possible (Figure 7). Profile A runs from the beach and causeway through parcel P and EP 5 and Profile B runs from the beach and causeway through the wetland and upslope to the center of parcel P Based on the data presented in Figure 7 Profile A is approximately 50 ft higher. The total bluff height, however, is broken up by the causeway that was blasted into the bedrock; the bluff top is 25 ft above the causeway. Bluff height at Profile B is approximately 55 ft with the base of the bluff at an elevation of ft MLLW. The slope at parcel P was bowl shaped with steep slopes of up to 68 degrees towards

18 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 15 COASTAL GEOLOGIC SERVICES, INC. the upper 1/3 of the bluff face (Figure 7). While Parcel P exhibited similar bluff height as that of Profile B (and parcel P117668) it also exhibited a gentler grade and apparent longer recurrence interval of past slope failures compared to parcel P The aspect of this bluff is north and is offered natural protection from wave attack provided by the bedrock headland at the southern end of the project area. The bluff at parcel P exhibits a north northwest aspect and represents the highest and steepest of the three parcels assessed, however the toe of the bluff is also inset further south than at the other parcels. Location and Elevation of Bluff Toe Parcel P is likely located on bedrock so the lower slope or more of this parcel is inherently stable. Parcel P is set back approximately 100 ft from the waterward toe of the revetment and at an elevation of +14 ft MLLW, as measured in GIS. Should the revetment rock be removed and the causeway fill material left to naturally erode, the bluff toe at this parcel is well protected from wave attack based on the distance from the causeway and beach, with the bank toe elevation 6 ft above MHHW (MHHW = +8 ft MLLW). Parcel P is set back approximately 140 ft from the waterward toe of the revetment and also an elevation of +14 ft MLLW, as measured in GIS (Profile B in Figure 7). The bluff toe at this location is well away from wave attack following potential removal of the revetment. House Setback to Top of Bluff As measured in GIS and survey data, all 3 of the houses on the respective parcels assessed have an adequate set back of 65 to 80 ft from the bluff crest. This is far greater than the minimum setback recommended by AES (1992) of 25 ft. Overall, it is the conclusion of these geologists that removing the revetment rock would not further destabilize the banks near the houses in the study or pose threats to the homes associated with these bluffs, and that the proposed revetment removal action is therefore feasible. Property management including proper vegetation management and surface water drainage control are recommended for the bluff properties assessed here that already exhibit a degree of slope instability. Implementation Considerations and Analysis Methods of rock removal include overland using trucks or by water with a barge. Both methods have been explored through review of existing information (ATSI 2012) and new interviews with contractors, along with our professional judgment based on over 20 years of implementing projects in the Puget Sound region. Two removal methods are outlined here along with preliminary, planning level cost estimates. Removal by Truck Overland Considerations for removal overland by truck include:

19 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 16 COASTAL GEOLOGIC SERVICES, INC. Opening up the right of way at the north end of Puget Road (the beginning of the foot trail near 2 driveways) would likely require moving and replacing existing small rock walls, fences, mailboxes, trees Avoid using the driveway at 2420 Puget Road (See Barrett property on Figure 6) Steep grade from access point going down to the causeway to the north Small trees growing in and adjacent to trail would need to be removed South end of foot trail was recently graded and graveled, and adjacent areas seeded with grass; these and other areas along the causeway in the project area may need to be temporarily improved prior to commencing project work Entire construction working and access area would need to be revegetated and repaired All trees would need to be cleared from the top of the causeway to allow truck access Strandberg Construction provided a preliminary cost estimate for overland rock removal (ATSI 2012). This estimate totaled $213,584 without tax for the removal of 1,700 CY of rock, and not including design, surveying, permitting, or oversight (Table 4 ATSI 2012). We project that this estimate from Strandberg Construction would increase to approximately $314,094 without tax for removal of 2,500 CY of rock quantified for this feasibility assessment. Removal by Barge Considerations for removal by barge include: Would likely need to avoid grounding on eelgrass Only access is several points along the southern half of the beach where beach is sandy and mostly devoid of large boulders (also where majority of the rock is located) Would likely need to move a small number of large boulders from the intertidal sandy beach Work would be tide dependent, with different work areas limited by tide height Would require storage facility for rock Larry Jay, the owner of JTC barge transport company, was consulted and performed a site visit along with Johannessen on June 22, Jay was given the survey sheets (Appendix A) and the estimated total volume of 2,500 CY. Jay gave a preliminary estimate of $100,000 (not including tax) to complete removal of all the rock (Alternative 2). However, this was based on incomplete assessment of all project logistics, and the use of a higher total cost will therefore be incorporated into the cost estimate, below. JTC was told to plan on bringing half of the removed rock to the north shore of Fidalgo Island and stockpile it in several discrete locations along the eastern end of the proposed new Guemes Channel trail corridor on the upper beach (pending plans from City of Anacortes; reuse is further discussed below) for future use by the City of Anacortes. The estimate would likely be the same whether JTC was taking all of the rock away or leaving half on the north shore, as the full volume of rock would be much more than Jay would like to resell. Moving the rock from the beach to a storage yard is a considerable amount of work including multiple handling efforts, and the value of the rock in place is

20 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 17 COASTAL GEOLOGIC SERVICES, INC. therefore quite small. Constraints include not being able to land the barge on the boulder and cobble beach along the central and western end of the potential, future Guemes Channel Trail corridor. This cost estimate is greatly reduced from the quote provided by Culbertson Marine Construction of $700,000 to $800,000 (ATSI 2012). A more detailed cost estimate using CGS cost estimating and project implementation experience along with the quote from JTC will be further developed in both the 30% and 100% design stages, which will include additional project elements such as sales tax, permitting, potential site enhancement, monitoring, and construction oversight. Rock Reuse CGS had several discussions with City of Anacortes Parks Director Gary Robinson during the preparation of this report. The purpose of these discussions was to determine reasonable reuses of the riprap removed from this site, if practical. The City will have final say as to the appropriate fate of the armor rock. Other than letting a contractor take the rock away for resale in trade for offering a lower removal charge, two potential uses of the rock were mentioned: Repair of the failing former railroad revetment along the central and eastern reach of the planned future Guemes Channel Trail Construct a trail extension from the south edge of the riprap removal area northeastward to the uplands near the south property line of the WWU Shannon Point Marine Center Guemes Channel Trail The potential Guemes Channel Trail extension would run from the recently completed western portion of the trail over to the Lovric s Sea Craft marina area. This is an approximately 3,500 4,000 ft long reach. The already completed western portion is on the order of 2,000 ft long. The City of Anacortes Public Works Department is beginning design work for repair of the old railroad grade for the Guemes Channel Trail extension. Portions of the 1890s railroad grade, the foundation of the trail extension, have small and large washouts. It is understood that riprap will need to be imported to repair some or all of these washout areas. City engineers are considering bridging some of these gaps, or washouts, in preparation for future trail construction; however the cost may be prohibitive. We also understand the City has hired a permit specialist which is currently in discussion with the engineers about these trail issues. Since the quantity of rock needed for the Guemes Channel Trail work is unknown, it is very difficult to attempt to plan logistics for this potential action. However, unloading and staging rock in discrete locations along the future Guemes Channel trail is a good option for rock storage if future development of the trail is nearly certain. Potential New Trail Extension/ Ramp As explained by Gary Robertson of the City of Anacortes Parks Department, the City is considering developing a new trail starting from the short trail reach off of the north end of Puget Way. This trail would run near the southern property line of the WWU owned Shannon Point Marine Center (Figure 6). The proposed trail would gain elevation to the east as it reached the uplands. The route could run on some combination of the southern edge of the WWU Shannon Point Marine Center and/or through the community owned parcel between the houses and

21 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 18 COASTAL GEOLOGIC SERVICES, INC. the WWU property. The trail would continue eastward to reach the Washington State Ferry Terminal area. In order to gain trail access to the uplands, a means of reaching the trail from the south edge of the riprap removal area (where the short trail section exists) is required. This would entail placement of trail access across approximately horizontal ft with an approximate net elevation gain of approximately ft. This trail route would need to avoid the upland residential properties. A 30 ft community owned easement exists along the north edge of this strip of properties (Figure 6), which the City is investigating whether or not the restrictions and uses attached to this parcel will allow for trail development. Alternatively, the trail would run immediately north of this 30 ft east west oriented parcel. The area below the developed upland lots is on a slope that abuts the backshore wetland landward of the railroad causeway within the study area. The wetland could be a substantial constrain on adjacent filling and grading. The entire area is forested with immature alder, elderberry, young Douglas fir, and scattered western redcedar and western hemlock trees. Groundcover species include sword fern, nettles, and a variety of other native species along with very small amounts of Himalayan blackberry. The geology was investigated briefly. The upper portion of the bank in this slope appeared to contain gravelly sand which overlies sand with lesser amounts of gravel. Below that clay and perhaps glacial till were encountered. Determining the exact nature of the soils here will require additional investigation. It appears as some amount of fill soil was pushed over the crest of the bank from above containing boulders and a variety of other grain sizes. The slopes south and southeast of the wetland on this potential trail area varied. The upper bank slope was as steep as 50 degrees from vertical (Figure 7). The majority of the bank face was sloped from 30 to 40 degrees with lesser gradients on the lower portions of the slope. Slopes this steep in unconsolidated glacial or nonglacial sediments present another substantial constraint to developing a trail in this area. If this trail ramp were to be built using salvaged riprap from the project site, it would require getting heavy equipment to the site. The trail immediately south of the project area would need to be improved as well; therefore, this may make removal of the remainder of the riprap by truck slightly more attractive. In any event, heavy equipment would need to reach the site by land or by barge to move riprap into this proposed trail ramp. Access for heavy equipment by land would require the same amount of additional work as removal of riprap by land would require. See section Removal by Truck Overland. Preferred Alternative Design drawings for the preferred alternative have been advanced to the 60% design level. A large format (11x17 ) design sheet set is attached which shows existing and proposed conditions, along with details and cross sections (Appendix A). This design will be further developed into final construction drawings in the next phase. A small format (8.5x11 ) design sheet set is also attached for permitting with the US Army Corp of Engineers (USACE; Appendix A).

22 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 19 COASTAL GEOLOGIC SERVICES, INC. Cost Estimate A cost estimate was developed using a CGS cost estimating spreadsheet, some of which was first incorporated into a spreadsheet developed by CGS and other project leads for the Puget Sound Nearshore Estuary Restoration Project (PSNERP) and WDFW for conceptual design of 34 different projects around the Puget Sound region (ESA et al. 2012). The cost estimating work for the project relied on past project cost data, and general knowledge of remote access sites such as this. Specific costs were estimated for barge use, revetment removal, and excavation and grading of the outer face of the causeway fill, and presented in Table 5. Design and permit costs were not included in the cost estimate. Mobilization was assumed to be 10% of the total estimated costs for project elements for this site. Estimates of the cost of minimal erosion control and construction management were included as percentages of the total of project element, along with a contingency of 20%. The following cost estimate was developed for the preferred alternative for planning purposes (Table 5). The total estimated cost without contingency was estimate at just under $140,000. With 20% contingency added, the total cost was just under $168,000.

23 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 20 COASTAL GEOLOGIC SERVICES, INC. Table 5. Cost estimate for Preferred Alternative based on 60% design. Action Name: Construction Cost Estimate for Shannon Point Revetment Removal, Anacortes, WA REMEDY: Construction Period Date: 1/11/14 By: Jonathan Waggoner, Jim Johannessen, LEG; CGS Preferred Alternative: Revetment Removal TBD Note: PRELIMINARY, based on 60% Design only Item Unit of Measure Unit Cost Qty Total Cost Notes MOBILIZATION AND ACCESS for construction activities Mobilization/Demob (Equipment, Personnel, Planning, Financial) LS 10% 1 $12,417 Tug and barge-1,000 ton capacity Days $4, $40,000 Site Demolition Activities No structures to remove 0 $0 Hazardous/Contaminated Waste Removal None anticipated 0 $0 EARTHWORK Revetment removal for haul offsite CY $ $62,500 General mobilization of people and equipment Barge-specific costs Remove entire revetment, including rock toppled to upper beach Excavation - Lowland Grading CY $ $12,500 CY $ $2,500 Removal of fill above the revetment rock to match new bank slope Placement of cut sediment on exposed beach to match existing beach grade Vegetation & Erosion Control Erosion / sediment BMPs - Temp. % 2.5% 1 $3,104 Final Design & Construction Management Final design, engineering % 18% 1 $0 % of total construction cost; low cost for minimal actions Permitting % 6% 1 $0 Construction oversight weeks $3,334 2 $6,668 Construction Cost Total Subtotal without percentage-based costs $124,168 Subtotal of percentage-based costs $15,521 Assume 1 person at total cost of $200k/ yr: this is full time observation and contract admin; would be spread over Total Cost $139,689 Contingency (20%) $27,938 Total Cost with Contingency $167,627 Limitations of This Report This report was prepared for the specific conditions present at the subject property to meet the needs of the specific client. No one other than the client should apply this report for any purposes other than that originally contemplated without first conferring with the geologist who prepared this report. The findings and recommendations presented in this report were reached based on field visits and background information. The report is based on examination of surface features, bank exposures, soil characteristics, beach features, and coastal processes. In addition, conditions may change at the site due to human influences, floods, earthquakes, groundwater regime changes, or other factors.

24 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 21 COASTAL GEOLOGIC SERVICES, INC. Thank you for engaging the professional services of Coastal Geologic Services, Inc. If we can be of any additional assistance please contact our office at (360) References Aqua Terr Systems, Inc Shannon Point rip rap removal project, feasibility and cost estimate study. Anacortes, Washington. Pp. 22. Carlson, R.L., A gravity study of the Cypress Island peridiotite, Washington: University of Washington Master of Science thesis, 39 p., 2 plates. Clancy, M., I. Logan, J. Lowe, J. Johannessen, A. MacLennan, F.B. Van Cleve, J. Dillon, B. Lyons, R. Carman, P. Cereghino, B. Barnard, C. Tanner, D. Myers, R. Clark, J. White, C. A. Simenstad, M. Gilmer, and N. Chin Management Measures for Protecting the Puget Sound Nearshore. Puget Sound Nearshore Ecosystem Restoration Project Report No Published by Washington Department of Fish and Wildlife, Olympia, WA. Dragovich, J. D., G. T. Petro, G.W. Thorsen, S.L. Larson, G.R. Foster, and D.K. Norman, Geologic Map of the Oak Harbor, Crescent Harbor, and Part of the Smith Island 7.5 minute Quadrangles, Island County, Washington: Washington Division of Geology and Earth Resources Geologic Map GM 59, 3 sheets, scale 1:24,000. Dragovich, J. D., Troost, M. L., Norman, D. K., Anderson, G., Cass, J., Gilbertson, L. A., and McKay, D. T. Jr., Geologic Map and Interpreted Geologic History of the Anacortes South and La Conner 7.5 minute Quadrangles, Skagit County, Washington: Washington Division of Geology and Earth Resources Geologic Map, Open File Report Easterbrook, D.J., Map showing engineering characteristics of geologic materials in western Whatcom County, Washington: U.S. Geological Survey Miscellaneous Investigation Series Map I 854 D, 1 sheet. ESA, Anchor QEA, KPFF, and CGS, Strategic Restoration Conceptual Engineering Design Report. Prepared for Puget Sound Nearshore Ecosystem Restoration Project and WDFW, Seattle, WA. Johannessen, J.W. and A.J. MacLennan, Beaches and Bluffs of Puget Sound. Puget Sound Nearshore Ecosystem Restoration Project Report No Published by Seattle District, U.S. Army Corps of Engineers, Seattle, Washington. Keuler, R.F., Map showing coastal erosion, sediment supply, and longshore transport in the Port Townsend 30 by 60 minute quadrangle, Puget Sound region, Washington: U.S. Geologic Survey Miscellaneous Investigations Map I 1198 E, scale 1:100,000. Lapen, T.J., Geologic map of Bellingham 1:100,000 quadrangle, Washington, Washington Division of Geology and Earth Resources Open File Report MacLennan, A.J., and J.W. Johannessen North Fidalgo Island geomorphic assessment & drift cell restoration prioritization. Prepared from Skagit County Marine Resources Committee. Prepared by Coastal Geologic Services, Inc. Pp. 35, 12 Maps. MacLennan, A.J., J.W. Johannessen, S.A. Williams, W. Gerstel, J.F. Waggoner, and A. Bailey, Feeder Bluff Mapping of Puget Sound. Prepared for the Washington State Department of Ecology, 111p. NOAA. Mean Higher High Water (MHHW) for the Shannon Point area as averaged from the Bowman Bay and Armatige Island benchmarks. Penttila, D. E Marine Forage Fishes in Puget Sound. Puget Sound Nearshore Partnership Report No , Published by Seattle District, U.S. Army Corps of Engineers, Seattle, Washington Simenstad, C., Ramirez, M., Burke, J., Logsdon, M., Shipman, H., Tanner, C., Davis, C., Fung, J., Block, P., Fresh, K., Campbell, S., Myers, D., Iverson, E., Bailey, A., Schlenger, P., Kiblinger, C., Myre, P., Gerstel, W., and MacLennan, A., Historic Change and Impairment of Puget Sound Shorelines: Puget Sound Nearshore

25 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 22 COASTAL GEOLOGIC SERVICES, INC. Ecosystem Project Change Analysis. Puget Sound nearshore Report No Published by Washington Department of Fish and Wildlife, Olympia, Washington, and U.S. Army Corps of Engineers, Seattle, WA. Schwartz, M.L., Harp, B.D., Taggart, B.E., and Crzastowski, M., Net shore drift of Washington State, Washington Department of Ecology, Shorelands and Coastal Zone Management Program, Olympia, WA. Slocum, Tom, Field Inventory of Armoring. Memorandum to Shannon Point Shoreline Armoring Project File. Washington Department of Ecology (Ecology), Coastal Zone Atlas of Washington, Volume 2, Skagit County. Olympia, WA. Washington Department of Fish and Wildlife, Priority Habitat Species Database Information. Washington State Department of Natural Resources (DNR), Surface Geology, 1,100,000 scale [Geodatabase]. Division of Geology and Earth Resources, Olympia, WA. Coastal Geologic Services, Inc. Jim Johannessen, Licensed Engineering Geologist, MS Stephanie Williams Licensed Geologist ATTACHMENTS: Figure 1. Shannon Point revetment removal study area location and net shore drift map. Figure 2. Shannon Point geologic mapping at 1:100,000 scale (DNR 2010). Figure 3. Shannon Point site features map. Figure 4. Shannon Point historic conditions map. Figure 5. Shannon Point slope stability mapping in the project area (Ecology 1979). Figure 6. Shannon Point and vicinity ownership information map. Figure 7. Profiles of slopes waterward of houses closest to the rock revetment. Figure 8. Restoration alternatives for the Shannon Point revetment and causeway. Photo Page 1. Oblique aerial photograph of the rock revetment and railroad causeway (Ecology 2006). Photo Page 2. Geologic units and beach characteristics.

26 Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, Page 23 COASTAL GEOLOGIC SERVICES, INC. Photo Page 3. Rock revetment sections 1 7, south to north with 3 ft scaled grid. Photo Page 4. Test pit excavations for causeway materials exploration. Photo Page 5. Test pit excavations for causeway materials exploration and wetland observations. APPENDIX A: 60% Design Sheet Set for Permitting large format (9sheets) 60% Design Sheet Set for Permitting small format (9sheets)

27 Legend Net shore-drift (NSD) Left to Right Right to Left No Appreciable Drift NSD Direction Miles A 1:24,000 B e l l i n g h a m C h a n n e l Strait R o sario CYPRESS ISLAND Project Area Bell ^_ i ngh am C hannel GUEMES ISLAND City of Anacortes FIDALGO ISLAND Fidalgo Island, Skagit County 1:500,000 Shannon Point revetment removal project area Drift Cell SK-D-2 Figure 1. Shannon Point revetment removal study area location and net shore-drift map. USGS Topographic Quadrangles, LiDAR Hillshade, and ESRI 2010 background imagery.

28 Legend Geologic Unit Qf - Fill Qb - Beach Qp - Peat Qgt - Vashon till A 1:2,400 Ju(f) - Ultramafic rocks Ju(f) wtr Qgt Feet Qp Project Area Qgt Ju(f) Qb Qf Ju(f) Northwest Fidalgo Island, Skagit County 1:48,000 Qgt Ju(f) Figure 2. Shannon Point geologic mapping at 1:100,000 scale (DNR 2010). ESRI 2010 background imagery.

29 Legend XW Native bluff Test pits Section breaks Railroad causeway Survey rock Approximate wetland A 1:1,200 Section Feet Section 6 Section 5 Section 4 Native bluff north XW Section 3 Section 2 TP 2 TP 7 TP 6 Section 1 TP 1 TP 8 TP 9 TP 10 TP 5 TP 3 TP 4 XW Native bluff south Figure 3. Shannon Point site features map Skagit County background imagery.

30 Legend XW Native bluff TP 5 TP 6 Survey rock Waterward causeway Feet A 1:2,000 Coarsening of beach sediment Bluffs fronting the beach Approx. historic MLLW line XW Native bluff north Lost beach/ intertidal TP 6 TP 5 Rocky headland XW Native bluff south Figure 4. Shannon Point historic conditions map with current features for comparison. T-sheet #1667 (c. 1885) background imagery.

31 Figure 5. Shannon Point slope stability mapping in the project area showing stable slopes (Ecology 1979;

32 Legend A Parcel boundaries Rock revetment 1:2,400 Railroad causeway P31555 DNR P31547 Western Washington University Feet P31556 City of Anacortes P31549 Western Washington University P City of Anacortes P City of Anacortes P Blackwood P Nelson P Worra P Cornelius P Berg P Stringer P Sunset Cove P Hanson P Callahan P118048, P Sunset Cove P Ballentine P Chebier P31559, P31554 Barrett P31553 Olich-Tweten Figure 6. Shannon Point and vicinity parcel ownership information map Skagit County background imagery.

33 Legend Parcel boundaries Rock revetment MHW, 1885 A 1:1,200 XW Ponded water, May 2013 Native bluff meets causeway EP-3 EP-5 Geology Qgt - Vashon till XW Ju(f) - Ultramafic rocks Feet XW EP-5 A B EP-3 Figure. 7 Profiles of slopes waterward of houses closest to the rock revetment Skagit County background imagery. Profiles derived from USGS LiDAR flown in 2006.

34 Alternative 1 Alternative 2 Alternative 3 Legend Proposed BluffToe Revetment Removal Causeway Removal A 1:1,200 Potential Saltmarsh Habitat Rock to Remain Potential Short-term Erosion Existing Freshwater Wetland Feet Figure 8. Restoration alternatives for the Shannon Point revetment and causeway Skagit County background imagery.

35 Photo Page 1. Oblique aerial photograph of the rock revetment and railroad causeway (Ecology 2006). Project Area

36 Nonglacial deposits north of project area, Qc(o) or Qc(w) Glacial till, just north of the site, Qgt Native bedrock exposed at rocky headland south Ju(f) Native bedrock skirt of angular cobbles, south end Sandy beach area, centrally located at site Photo Page 2. Geologic units and beach characteristics. Cobble beach area, north end of site

37 Section 1 south end, adjacent to bedrock headland Section 2 scarps apparent near causeway crest Section 3 long section and lower bank Section 4 lower bank and willow trees at crest Section 5 revetment blown out from likely debris flow Section 6 bank/causeway height is reduced Section 7 Low rock and groin configuration. Scour behind or down-drift (left side) of this section. Photo Page 3. Rock revetment sections 1 7, south to north with 3 ft scaled grid. Figure 3 shows section breaks.

38 TP 1 Angular native bedrock, likely fill material TP 2 Angular granitic rock, likely fill material TP 3 Medium to coarse orange sand, pebble, likely fill TP 4 Silty fine sand, sub angular pebble, likely fill TP 5 Fine to medium gray sand, beach material Photo Page 4. Test pit excavations for causeway materials exploration. TP 6 Medium to coarse sand, pebbles, beach material

39 TP 7 Silty fine sand and sub-angular pebble, likely fill TP 8 Sandy silt with sub-rounded pebbles, likely fill TP 9 Angular native bedrock in silty matrix, likely fill TP 10 Silt with angular clasts, likely fill Angular native bedrock boulder in causeway Depressional wetland looking northeast Photo Page 5. Test pit excavations for causeway materials exploration and wetland observations. Table 1 has full test pit descriptions.

40 SHANNON POINT BULKHEAD REMOVAL West Shore Anacortes, Skagit Co., WA For: Northwest Straits Foundation SURVEY NOTES: VICINITY MAP: INDEX TO DRAWINGS: C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg Horizontal Datum: NAD83 HARN State Plane WA South Based on DGPS observation on 5/28-29/13 using a Trimble GeoHX 6000 post-processed to WSRN base station COUP Vertical Datum: Mean Lower Low Water (MLLW) Based on water level observations at low tide on 5/28-29/13. Topography shown within survey boundary obtained 5/28-29/13 and 12/30/13 using Lieca TCR-1105 total station with direct rod measurements. Additional topography outside boundary from USGS LiDAR data flown in 2006, shown at 2 FT contour intervals for reference only. LiDAR obtained in NAVD88 and datum shifted to MLLW using: 0.0 ft NAVD88 = 0.52 ft MLLW (VDatum v 3.1). Aerial photograph shown on Sheet C2.1 from Skagit County flown image WASKAG021006, used as-is here. Parcel boundaries shown on Sheet C2.1 are approximate only. No boundary survey was completed as part of this work. Boundaries obtained from Skagit County GIS in DWG format, and used as-is here. MONUMENT LIST: NAME EASTING NORTHING ELEV. TYPE CGS ' ' 21.03' 2x2 HUB CGS ' ' 21.46' 2x2 HUB DRIVING DIRECTIONS: From I-5 exit 230 proceed west-bound on State Route 20. At 11.4 miles follow State Route 20 Extension forward toward Anacortes Ferry Terminal. Bear left at turn-off to ferry terminal onto Sunset Ave. Turn right onto Sunset Cove Rd. Follow Sunset Cove to Washington Ct. Park at end of cul-de-sac and follow marked foot trail to beach. 60% DESIGN FOR PERMITTING Not For Construction C1.1 COVER SHEET C2.1 EXISTING CONDITIONS - OVERVIEW C2.2 EXISTING CONDITIONS - SOUTH DETAIL C2.3 EXISTING CONDITIONS - NORTH DETAIL C3.1 DEMOLITION PLAN C4.1 PROPOSED CONDITIONS - SOUTH C4.2 PROPOSED CONDITIONS - NORTH C5.1 PROFILES 1-3 C5.2 PROFILES 4-6 LEGEND Existing Minor Contour (Survey) Existing Major Contour (Survey) Existing Minor Contour (2 ft int.; LiDAR) Existing Major Contour (2 ft int.; LiDAR) Proposed Minor Contour Proposed Major Contour OHWM (Ordinary High Water Mark) MHHW (+8.0 ft MLLW) Landward Extent of Eelgrass Approximate Parcel Boundaries Rock Revetment Approximate Extent of Backshore Pond Test Pit Hub and Tack Remove Revetment Rock Cut Top of Bank to Match Lower Slope Fill to Adjacent Beach Grade REVISIONS 7 JAN JAN 2014 DRAWN BY: JFW DESIGNED BY: CHECKED BY: JWJ Shannon Point Bulkhead Removal Cover Sheet SCALE: AS NOTED DATE: 1/10/14 DATE SURVEYED: 5/28-29/13 12/30/13 MLLW=0.0' SHEET: C1.1 Location, Index, and Legend For: Northwest Straits Foundation 1 OF 9

41 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg CT WASHINGTON P1 P2 SHEET C2.2 P3 Rosario Strait P FEET 60% DESIGN FOR PERMITTING Not For Construction SHEET C2.3 SURVEY EXTENT P5 P6 MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C2.1 2 OF 9 Shannon Point Bulkhead Removal Existing Conditions - Overview Topography and Site Features For: Northwest Straits Foundation DRAWN BY: JFW DESIGNED BY: CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014

42 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg P1 Causeway FEET 60% DESIGN FOR PERMITTING Not For Construction Rosario Strait P2 P3 MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C2.2 3 OF 9 Shannon Point Bulkhead Removal Existing Conditions - South Detail Topography and Site Features For: Northwest Straits Foundation DRAWN BY: JFW DESIGNED BY: CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014

43 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg Causeway P3 P4 Rosario Strait P5 Failed Revetment Area P FEET 60% DESIGN FOR PERMITTING Not For Construction MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C2.3 4 OF 9 Shannon Point Bulkhead Removal Existing Conditions - North Detail Topography and Site Features For: Northwest Straits Foundation DRAWN BY: JFW DESIGNED BY: CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014

44 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg P1 P2 P3 Potential Barge Access Corridor Notes 1. Remove rocks from revetment and beachface for offsite disposal. Remove toppled rock from beachface waterward of revetment toe. 2. Excavate (cut) top of bank above revetment to match slope exposed by rock removal. 3. Use excavated sediment removed from top of bank above revetment for filling voids left by revetment toe rock removal SHEET C4.1 P FEET 60% DESIGN FOR PERMITTING Not For Construction Rosario Strait SHEET C4.2 P5 P6 MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C3.1 5 OF 9 Shannon Point Bulkhead Removal Demolition Plan DRAWN BY: JFW DESIGNED BY: JWJ CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014 For: Northwest Straits Foundation

45 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg P1 Limit of Excavation Causeway P2 Rosario Strait FEET 60% DESIGN FOR PERMITTING Not For Construction P3 P4 MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C4.1 6 OF 9 Shannon Point Bulkhead Removal Proposed Conditions - South Detail DRAWN BY: JFW DESIGNED BY: JWJ CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014 For: Northwest Straits Foundation

46 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg Rosario Strait P4 P5 Limit of Excavation P FEET 60% DESIGN FOR PERMITTING Not For Construction MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C4.2 7 OF 9 Shannon Point Bulkhead Removal Proposed Conditions - North Detail DRAWN BY: JFW DESIGNED BY: JWJ CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014 For: Northwest Straits Foundation

47 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg Existing Ground (LiDAR) Proposed Finished Grade Fill With Soil Cut Above Revetment Cut Slope Above Revetment to Consistent Slope Remove Revetment Rock Remove Exposed Rock in Fill Surface MHHW (+8.0' MLLW) Existing Ground (survey) Cut Slope Above Revetment to Consistent Slope Remove Revetment Rock Remove Exposed Rock in Fill Surface Proposed Finished Grade MHHW (+8.0' MLLW) Fill With Soil Cut Above Revetment Existing Ground (survey) Cut Slope Above Revetment to Consistent Slope Remove Revetment Rock Remove Exposed Rock in Fill Surface Proposed Finished Grade Fill With Soil Cut Above Revetment MHHW (+8.0' MLLW) Existing Ground (survey) 60% DESIGN FOR PERMITTING Not For Construction MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C5.1 8 OF 9 Shannon Point Bulkhead Removal Cross Sections 1-3 DRAWN BY: JFW DESIGNED BY: JWJ CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014 For: Northwest Straits Foundation

48 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_TabloidSet.dwg Existing Ground (LiDAR) Proposed Finished Grade Fill With Soil Cut Above Revetment Cut Slope Above Revetment to Consistent Slope Remove Revetment Rock Remove Exposed Rock in Fill Surface MHHW (+8.0' MLLW) Existing Ground (survey) Remove Revetment Rock Proposed Finished Grade Fill With Soil Cut Above Revetment MHHW (+8.0' MLLW) Existing Ground (survey) Cut Slope Above Revetment to Consistent Slope Proposed Finished Grade Fill With Soil Cut Above Revetment Remove Revetment Rock Remove Exposed Rock in Fill Surface MHHW (+8.0' MLLW) Existing Ground (survey) 60% DESIGN FOR PERMITTING Not For Construction MLLW=0.0' SCALE: AS NOTED DATE: 1/10/14 SHEET: C5.2 9 OF 9 Shannon Point Bulkhead Removal Cross Sections 4-6 DRAWN BY: JFW DESIGNED BY: CHECKED BY: JWJ DATE SURVEYED: 5/28-29/13 REVISIONS 7 JAN JAN 2014 For: Northwest Straits Foundation

49 SHANNON POINT BULKHEAD REMOVAL West Shore Anacortes, Skagit Co., WA For: Northwest Straits Foundation VICINITY MAP: INDEX TO DRAWINGS: 1 COVER SHEET 2 EXISTING CONDITIONS - OVERVIEW 3 EXISTING CONDITIONS - SOUTH DETAIL 4 EXISTING CONDITIONS - NORTH DETAIL 5 DEMOLITION PLAN 6 PROPOSED CONDITIONS - SOUTH 7 PROPOSED CONDITIONS - NORTH 8 PROFILES PROFILES 4-6 DRIVING DIRECTIONS: From I-5 exit 230 proceed west-bound on State Route 20. At 11.4 miles follow State Route 20 Extension forward toward Anacortes Ferry Terminal. Bear left at turn-off to ferry terminal onto Sunset Ave. Turn right onto Sunset Cove Rd. Follow Sunset Cove to Washington Ct. Park at end of cul-de-sac and follow marked foot trail to beach. LEGEND C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_PermitSet Existing Minor Contour (Survey) Existing Major Contour (Survey) Existing Minor Contour (2 ft int.; LiDAR) Existing Major Contour (2 ft int.; LiDAR) Proposed Minor Contour Proposed Major Contour OHWM (Ordinary High Water Mark) MHHW (+8.0 ft MLLW) Landward Extent of Eelgrass Shannon Point Bulkhead Removal Cover Sheet Northwest Straits Foundation 1155 N State St, Suite 402 Bellingham, WA Approximate Parcel Boundaries Rock Revetment Approximate Extent of Backshore Pond Test Pit Hub and Tack Remove Revetment Rock Cut Top of Bank to Match Lower Slope Fill to Adjacent Beach Grade PROPOSED: Bulkhead Removal IN: Rosario Strait COUNTY: Skagit STATE: WA APPLICATION BY: Northwest Straits Foundation 1155 N State St, Suite 402 Bellingham, WA (360) MLLW= 0.0 FT MHHW= +8.0 FT SCALE: AS SHOWN DATE: 10JAN14 SHEET: 1 OF: 9

50 FEET 60% DESIGN FOR PERMITTING Not For Construction P1 P2 P3 P4 P5 P6 C:\Civil3DProjects\SkagitCo\ShannonPt\ ShannonPtSurvey_PermitSet Shannon Point Bulkhead Removal Existing Conditions Overview Northwest Straits Foundation 1155 N State St, Suite 402 Bellingham, WA PROPOSED: Bulkhead Removal IN: Rosario Strait COUNTY: Skagit STATE: WA APPLICATION BY: Northwest Straits Foundation 1155 N State St, Suite 402 Bellingham, WA (360) MLLW= 0.0 FT MHHW= +8.0 FT SCALE: AS SHOWN DATE: 10JAN14 SHEET: 2 OF: 9