County: Skagit County G1400105 Northwest Straits … Skagit County Grant No: G1400105 PROJECT TITLE: Northwest Straits Project: Skagit County Marine Resources Committee Operations

County: Skagit County Grant No: G1400105

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.

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

COASTAL GEOLOGIC SERVICES, INC.

1711 Ellis St. Suite 103, Bellingham, WA 98225 (360) 647-1845 [email protected]

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 ....................................................................................................... 10

Preferred Alternative .............................................................................................................................. 10

Constraints .......................................................................................................................................... 11

Benefits ............................................................................................................................................... 11

Slope Stability Assessment for Preferred Alternative ............................................................................. 12

Integration of Previous Geology/Stability Work ................................................................................. 12

Geology and Stratigraphy ................................................................................................................... 14

Bluff Configuration .............................................................................................................................. 14

Location and Elevation of Bluff Toe .................................................................................................... 15

House Setback to Top of Bluff ............................................................................................................ 15

Implementation Considerations and Analysis ........................................................................................ 15

Removal by Truck Overland ................................................................................................................ 15

Removal by Barge ............................................................................................................................... 16

Rock Reuse .......................................................................................................................................... 17

Preferred Alternative .............................................................................................................................. 18

Cost Estimate .......................................................................................................................................... 19

Limitations of This Report ....................................................................................................................... 20

References .............................................................................................................................................. 21

ATTACHMENTS: ....................................................................................................................................... 22

APPENDIX A: ............................................................................................................................................ 23

Shannon Point Revetment Removal Feasibility and Preliminary Design Jan. 12, 2014 - 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 28th and 29th, 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.

Site Conditions

Overview

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.


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


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 wind‐

generated 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 shore‐

drift 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 Sound‐

wide 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


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 28th and 29th. 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,

2013. 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 cross‐

sectional 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.

Section

Average Rock

Height (FT)

Alongshore

Length (LF)

Cross-sectional

Area (SF) Volume (CY)

1 6 57 41 87

2 9 140 65 335

3 2 55 25 51

4 9 76 65 184

5 15 219 96 775

6 14 64 107 255

7 19 155 144 825

Total -- -- -- 2512

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


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


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

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.

TP 2 causeway

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.

TP 3 causeway

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.

TP 4 causeway

8- 12 inches 10 ft below causeway crest on landward side (near depressional wetland-about 3 ft above wetland). Silty fine sand with few random sub-angular to sub-rounded pebbles. Medium plasticity indicating fines. Likely native fill.

TP 5

depression

12- 15 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.

TP 6

depression

12- 15 inches North end of depression landward of causeway. Medium to coarse gray sand, few sub-rounded pebbles and cobbles. Native beach material.

TP 7 causeway

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.

TP 8 causeway

6 inches At top of causeway. Sandy silt with few medium sub-rounded pebbles. Likely native fill.

TP 9 causeway

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.

TP 10 causeway

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).


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.


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 ft2 of beach habitat and up to 4,900 ft2 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 +10.5 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


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 ft2 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 ft2 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


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

Habitat Benefits Project Constraints Relative Cost

1 - Full Restoration

Recovery of ~36,430 ft2 of beach/intertidal habitat

Recovery of up to ~4,900 ft2 of potential salt marsh

Increased potential forage fish spawning area

Increased bluff sediment input down-drift beaches and forage fish spawning 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

Highest: Greater than estimates given for Alt 2, more time and more material to remove

2 - Full Rock Removal

Recovery of ~15,250 ft2 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 down-drift beaches

Barge access will require clearing boulders from larger beach areas

Barge access or removal by truck similar to Alt 1

Moderate: $314,094 removal by truck (removal only; pretax)

$100,000 plus- removal by barge (removal only, before tax)

3 - Partial Rock Removal

Recovery of approximately 7,330 ft2 of beach/intertidal habitat, mainly at the south end of the site

Limited erosion of sandy sediment from causeway will benefit down-drift beaches

Leaves rock on the beach with less habitat benefit

Barge access or removal by truck similar to Alt 1

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


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


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


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 P117670 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


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 P117668 (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 P117670 and till underlying parcels P117669 and

P117668. 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 P117669 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 P117688. 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

P117670 and EP‐5 and Profile B runs from the beach and causeway through the wetland and upslope

to the center of parcel P117668. 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 +10.5 ft

MLLW. The slope at parcel P117668 was bowl shaped with steep slopes of up to 68 degrees towards


the upper 1/3 of the bluff face (Figure 7). While Parcel P117669 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 P117668. 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 P117668 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 P117670 is likely located on bedrock so the lower slope or more of this parcel is inherently

stable. Parcel P117669 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 P117668 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:


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, 2013. 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


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


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 300‐400 horizontal ft with an approximate net elevation gain of

approximately 45‐60 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).


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.


Table 5. Cost estimate for Preferred Alternative based on 60% design.

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.

Action Name:

Date:

By:

Note: PRELIMINARY, based on 60% Design only

REMEDY: Preferred Alternative: Revetment Removal

Construction Period TBD

ItemUnit of

MeasureUnit Cost Qty Total Cost Notes

MOBILIZATION AND ACCESS for construction activitiesMobilization/Demob(Equipment, Personnel, Planning, Financial) LS 10% 1 $12,417

General mobilization of people and equipment

Tug and barge-1,000 ton capacity Days $4,000 10 $40,000 Barge-specific costs

Site Demolition Activities No structures to remove 0 $0

Hazardous/Contaminated Waste RemovalNone anticipated 0 $0

EARTHWORKRevetment removal for haul offsite

CY $25 2500 $62,500Remove entire revetment, including rock toppled to upper beach

Excavation - LowlandCY $25 500 $12,500

Removal of fill above the revetment rock to match new bank slope

GradingCY $5.00 500 $2,500

Placement of cut sediment on exposed beach to match existing beach grade

Vegetation & Erosion ControlErosion / sediment BMPs - Temp.

% 2.5% 1 $3,104% of total construction cost; low cost for minimal actions

Final Design & Construction ManagementFinal design, engineering % 18% 1 $0

Permitting % 6% 1 $0

Construction oversightweeks $3,334 2 $6,668

Assume 1 person at total cost of $200k/ yr: this is full time observation and contract admin; would be spread over

Construction Cost TotalSubtotal without percentage-based costs $124,168

Subtotal of percentage-based costs $15,521

Total Cost $139,689

Contingency (20%) $27,938

Total Cost with Contingency $167,627

Construction Cost Estimate for Shannon Point Revetment Removal, Anacortes, WA

1/11/14

Jonathan Waggoner, Jim Johannessen, LEG; CGS


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) 647‐1845.

References Aqua‐Terr Systems, Inc. 2012. Shannon Point rip rap removal project, feasibility and cost estimate study.

Anacortes, Washington. Pp. 22.

Carlson, R.L., 1972. 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. 2009. Management

Measures for Protecting the Puget Sound Nearshore. Puget Sound Nearshore Ecosystem Restoration Project Report

No. 2009‐01. 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, 2005. 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., 2000. 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 2000‐6.

Easterbrook, D.J., 1976. 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, 2012. 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, 2007. Beaches and Bluffs of Puget Sound. Puget Sound Nearshore Ecosystem Restoration Project Report No. 2007‐04. Published by Seattle District, U.S. Army Corps of Engineers, Seattle, Washington.

Keuler, R.F., 1988. 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., 2000. Geologic map of Bellingham 1:100,000 quadrangle, Washington, Washington Division of Geology and Earth Resources Open File Report 2000‐5.

MacLennan, A.J., and J.W. Johannessen. 2008. 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, 2013. 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. 2007. Marine Forage Fishes in Puget Sound. Puget Sound Nearshore Partnership Report No. 2007‐03, 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., 2011. Historic Change and Impairment of Puget Sound Shorelines: Puget Sound Nearshore


Ecosystem Project Change Analysis. Puget Sound nearshore Report No. 2011‐01. 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., 1991. Net shore‐drift of Washington State, Washington Department of Ecology, Shorelands and Coastal Zone Management Program, Olympia, WA.

Slocum, Tom, 2011. Field Inventory of Armoring. Memorandum to Shannon Point Shoreline Armoring Project File.

Washington Department of Ecology (Ecology), 1979. Coastal Zone Atlas of Washington, Volume 2, Skagit County. Olympia, WA.

Washington Department of Fish and Wildlife, 2004. Priority Habitat Species Database Information.

Washington State Department of Natural Resources (DNR), 2010. Surface Geology, 1,100,000 scale [Geodatabase]. Division of Geology and Earth Resources, Olympia, WA. http://www.dnr.wa.gov/ResearchScience/Topics/GeosciencesData/Pages/gis_data.aspx

Coastal Geologic Services, Inc.

Jim Johannessen, Stephanie Williams

Licensed Engineering Geologist, MS 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.


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)

Be l l i ng h am

Ch a

nne l

USGS Topographic Quadrangles, LiDAR Hillshade, and ESRI 2010 background imagery.

Figure 1. Shannon Point revetment removal study area location and net shore-drift map.

Shannon Point revetment removal

project area

City of Anacortes

Bel

l in

gh

am

Ch

an

ne

l

1:500,000Fidalgo Island, Skagit County

LegendNet shore-drift (NSD)

Left to Right

Right to Left

No Appreciable Drift

1:24,000A

0 0.25 0.5Miles

NSD Direction

Drift Cell SK-D-2

_̂Project

Area

Ro

sari

o

Str

ait

FIDALGO ISLAND

GUEMESISLAND

CYPRESSISLAND

Qgt

Ju(f)

ESRI 2010 background imagery.

Figure 2. Shannon Point geologic mapping at 1:100,000 scale (DNR 2010).

1:2,400A

0 125 250Feet

Qgt

Qf

Ju(f)Qb

Qp

Ju(f)

wtr

Qgt

Ju(f)

Northwest Fidalgo Island, Skagit County 1:48,000

Project Area

LegendGeologic Unit

Qf - Fill

Qb - Beach

Qp - Peat

Qgt - Vashon till

Ju(f) - Ultramafic rocks

XW

XW

TP 9TP 8

TP 7

TP 6

TP 5

TP 4TP 3

TP 2

TP 1

TP 10

2009 Skagit County background imagery.

Figure 3. Shannon Point site features map.

1:1,200A

0 75 150Feet

Section 1

Section 2

Section 3

Section 4

Section 5

Section 6

Section 7

Survey rock

LegendXW Native bluff

Test pits

Section breaks

Railroad causeway

Approximate wetland

Native bluff south

Native bluff north

XW

XW

T-sheet #1667 (c. 1885) background imagery.

Figure 4. Shannon Point historic conditions map with current features for comparison.

LegendXW Native bluff

TP 5

TP 6

Survey rock

Waterward causeway

1:2,000A

0 125 250Feet

TP 5

TP 6

Rockyheadland

Lost beach/intertidal

Bluffs fronting the beach

Coarsening of beach sediment

Native bluff south

Native bluff north

Approx. historicMLLW line

Figure 5. Shannon Point slope stability mapping in the project area showing stable slopes (Ecology 1979; http://www.ecy.wa.gov/programs/sea/femaweb/Skagit/SK_5ith.jpg)


Figure 6. Shannon Point and vicinity parcel ownership information map.

1:2,400A

P31549Western Washington University

P31547Western Washington University

P31555DNR

P31556City of Anacortes

P116445City of

Anacortes

P117683 Sunset Cove

P118048, P117680

Sunset Cove

P116446City of

Anacortes

P117900Callahan

P117665Hanson

P117666Stringer

P117667Berg

P117668Cornelius

P117669Worra

P117670Nelson

P117671Blackwood

P117672Ballentine

P117673Chebier

P31553Olich-TwetenP31559, P31554

Barrett

LegendParcel boundaries

Rock revetment

Railroad causeway

0 150 300Feet

XW

XW

Figure. 7 Profiles of slopes waterward of houses closest to the rock revetment.

A B

LegendParcel boundaries

Rock revetment

MHW, 1885

Ponded water, May 2013

XW Native bluff meets causeway

EP-3

EP-5

GeologyQgt - Vashon till

Ju(f) - Ultramafic rocks

2009 Skagit County background imagery. Profiles derived from USGS LiDAR flown in 2006.

A1:1,200

0 75 150Feet

EP-5

EP-3

Figure 8. Restoration alternatives for the Shannon Point revetment and causeway.


Alternative 1 Alternative 2 Alternative 3

A1:1,200

LegendProposed BluffToe

Revetment Removal

Causeway Removal

Potential Saltmarsh Habitat

Rock to Remain

Potential Short-term Erosion

Existing Freshwater Wetland

0 75 150Feet

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

Project Area

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 Cobble beach area, north end of site

Photo Page 2. Geologic units and beach characteristics.

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.

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 TP 6 – Medium to coarse sand, pebbles, beach material

Photo Page 4. Test pit excavations for causeway materials exploration.

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.

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

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SURVEY NOTES:

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 2009 - 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.

SHANNON POINT BULKHEAD REMOVAL

West Shore Anacortes, Skagit Co., WA

For: Northwest Straits Foundation

INDEX TO DRAWINGS:

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

VICINITY MAP:

MONUMENT LIST:

NAME EASTING NORTHING ELEV. TYPE

CGS1 1190751.10' 554589.26' 21.03' 2x2 HUB

CGS2 1190645.37' 554157.75' 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.

LEGEND

60% DESIGN FOR PERMITTING

Not For Construction

SHEET C2.2

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P

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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.

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Limit of Excavation

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- N

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Limit of Excavation

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Rem

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Existing G

round

(survey)

Existing G

round

(LiD

AR)

Cut Slope Above Revetm

ent

to Consistent Slope

MH

HW

(+

8.0' M

LLW

)

MH

HW

(+

8.0' M

LLW

)

Rem

ove Revetm

ent Rock

Rem

ove Revetm

ent Rock

Proposed

Finished G

rade

Proposed

Finished G

rade

Proposed

Finished G

rade

Fill W

ith Soil Cut

Above Revetm

ent

Fill W

ith Soil Cut

Above Revetm

ent

Fill W

ith Soil Cut

Above Revetm

ent


ent

to Consistent Slope


ent

to Consistent Slope

Existing G

round

(survey)

Existing G

round

(survey)

Rem

ove Exposed Rock in Fill Surface

Rem


Rem


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Existing G

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(LiD

AR)

MH

HW

(+

8.0' M

LLW

)

MH

HW

(+

8.0' M

LLW

)

MH

HW

(+

8.0' M

LLW

)

Rem

ove Revetm

ent Rock

Rem

ove Revetm

ent Rock

Rem

ove Revetm

ent Rock

Proposed

Finished G

rade

Proposed

Finished G

rade

Proposed

Finished G

rade

Fill W

ith Soil Cut

Above Revetm

ent

Fill W

ith Soil Cut

Above Revetm

ent

Fill W

ith Soil Cut

Above Revetm

ent


ent

to Consistent Slope


ent

to Consistent Slope

Existing G

round

(survey)

Existing G

round

(survey)

Rem


Rem


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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


Cut Top of Bank to Match Lower Slope

Fill to Adjacent Beach Grade

SHANNON POINT BULKHEAD REMOVAL

West Shore Anacortes, Skagit Co., WA

For: Northwest Straits Foundation

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 1 - 3

9 PROFILES 4 - 6

VICINITY MAP:

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

DATE:

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PROPOSED:IN:COUNTY:STATE:APPLICATION BY:

OF:SHEET:

SCALE:

MLLW=MHHW=

Shannon Point Bulkhead RemovalCover Sheet

Northwest Straits Foundation

1 910JAN14

Bulkhead RemovalRosario Strait

SkagitWA

Northwest Straits Foundation1155 N State St, Suite 402Bellingham, WA 98225(360) 733-1725

1155 N State St, Suite 402Bellingham, WA 98225

AS SHOWN

0.0 FT

+8.0 FT

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Shannon Point Bulkhead RemovalExisting Conditions


2 910JAN14


SkagitWA


Overview


AS SHOWN

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3 910JAN14


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South Detail


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4 910JAN14


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North Detail


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Shannon Point Bulkhead RemovalDemolition Plan


5 910JAN14


SkagitWA



AS SHOWN

0.0 FT

+8.0 FT

0 80 160 240

FEET



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.

4. No cut in bank landward of failed revetment.

2

1

3

4

Potential Barge

Access Corridor

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OF:SHEET:

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Shannon Point Bulkhead RemovalProposed Conditions


6 910JAN14


SkagitWA


South Detail


AS SHOWN

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+8.0 FT

0 50 100 150

FEET



Limit of Excavation

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Shannon Point Bulkhead RemovalProposed Conditions


7 910JAN14


SkagitWA


North Detail


AS SHOWN

0.0 FT

+8.0 FT

0 50 100 150

FEET



Limit of Excavation

Remove Exposed Rock in Fill Surface



MHHW (+8.0' MLLW)


Existing Ground

(survey)

Existing Ground

(LiDAR)

Cut Slope Above Revetment

to Consistent Slope

MHHW (+8.0' MLLW)

MHHW (+8.0' MLLW)



Proposed

Finished Grade

Proposed

Finished Grade

Proposed

Finished Grade

Fill With Soil Cut

Above Revetment

Fill With Soil Cut

Above Revetment

Fill With Soil Cut

Above Revetment


to Consistent Slope


to Consistent Slope

Existing Ground

(survey)

Existing Ground

(survey)

DATE:

C:\

Civ

il3D

Pro

ject

s\Sk

agit

Co

\Sh

ann

on

Pt\

13

-01

5-S

han

no

nP

tSu

rvey

_Per

mit

Set


OF:SHEET:

SCALE:

MLLW=MHHW=

Shannon Point Bulkhead RemovalProfiles 1 - 3


8 910JAN14


SkagitWA



AS SHOWN

0.0 FT

+8.0 FT





Existing Ground

(survey)

Existing Ground

(LiDAR)

MHHW (+8.0' MLLW)

MHHW (+8.0' MLLW)

MHHW (+8.0' MLLW)




Proposed

Finished Grade

Proposed

Finished Grade

Proposed

Finished Grade

Fill With Soil Cut

Above Revetment

Fill With Soil Cut

Above Revetment

Fill With Soil Cut

Above Revetment


to Consistent Slope


to Consistent Slope

Existing Ground

(survey)

Existing Ground

(survey)

DATE:

C:\

Civ

il3D

Pro

ject

s\Sk

agit

Co

\Sh

ann

on

Pt\

13

-01

5-S

han

no

nP

tSu

rvey

_Per

mit

Set


OF:SHEET:

SCALE:

MLLW=MHHW=

Shannon Point Bulkhead RemovalProfiles 4 - 6


9 910JAN14


SkagitWA



AS SHOWN

0.0 FT

+8.0 FT



Documents

County: Skagit County G1400105 Northwest Straits … Skagit County Grant No: G1400105 PROJECT TITLE: Northwest Straits Project: Skagit County Marine Resources Committee Operations