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16-104364
CITY OF Federal Way Conditions of Shoreline Exemption Approval Federal Way Revised Code (FWRQ 15.05.130 `Shoreline Exemption' Elliott Slope Stabilization, File #16-104364-00-SH The Planning Division has reviewed the shoreline substantial development permit exemption based on the exemption provision from WAC 173-27-040(2)(g), relevant code sections of FWRC Chapter 15.05 Shoreline Management, materials submitted September 2, 2016, and subsequent resubmittals received September 23, 2016, October 11, 2016, and November 1, 2016. PROPOSAL The applicant, GeoResources, LLC, on behalf of the property owners, Tom and Gloria Elliott, have proposed to construct an H-pile and timber lagging wall near the top slope to protect the upland residence, deck, and yard from future landslide. The property is located at 3500 SW Dash Point Road along the Puget Sound Shoreline. A landslide occurred on the north side of the property last winter that has impacted the Elliott property and the property to the north. The applicant submitted the Shoreline Exemption Permit Application on September 2, 2016. The failure scarp occurred just below the top of the bluff slope. The proposed retaining wall will be constructed above the failure area to retain the upland area and protect the existing residence and appurtenant structures. The house is placed on conventional foundation and the geotechnical report prepared by GeoResources, resubmitted October 11, 2016, indicates that the residence is at imminent risk of damage given the proximity and geometry of the slide. The applicant requested that immediate action take place to protect the residence. On October 11, 2016, the City's Building Division authorized the applicant to immediately start stabilizing the slope prior to the issuance of a building permit. The contractor was to proceed at their own risk until all pertinent documentation had been approved by the City and the City's geotechnical consultant, GeoDesign Inc. Pursuant to the 2015 IBC Section 105.2.1, emergency repairs may be performed in an emergency situation as long as a permit application is submitted within the next business day. The applicant has submitted all necessary permit applications. The building permit application, File #16-104959-00-SF, is currently under review. The proposed retaining wall will include steel H-piles driven into the underlying soils a minimum depth of 25 feet from the level of the bluff top with a height of up to four feet of exposed wall. Timber lagging will be installed between the piles where exposed. A small amount of backfill will be placed behind the wall lagging. All disturbed areas will have erosion control, including jute matting, mulch, seeding and/or hydroseed. In addition, surface water drainage was identified as a causative factor for the failure to the north. The applicant proposes the downspout line for the residence be tightlined to the lower portion of the slope. CODE ANALYSIS ■ Shoreline Management The subject property is designated `Urban Conservancy' in the city's Shoreline Management Plan (SMP) overlay. Areas within 200 feet of the Puget Sound marine shoreline, including the Urban Conservancy designation area, are regulated under the state's Shoreline Management Act, which is administered locally via the city's SMP. The project is exempt from Shoreline Substantial Development permit provisions pursuant to WAC 173-27-040(2)(g), construction on shorelands by an owner of a single-family residence and those structures and developments that are normal appurtenances. After the exemption permit was submitted, staff was notified by GeoResources of the urgency to start construction of the retaining wall. The City allowed the applicant to proceed with slope stabilization prior to issuing the Shoreline Substantial Development Exemption Permit. Plans have since been reviewed and are consistent with the SMP regulations. The City hereby approves the Shoreline Exemption Permit as conditioned below. a Critical Areas The subject property is also located within a Geologically Hazardous Area (GHA), erosion, steep slope, and landslide hazard area. Any actions proposed to repair the damaged hillside are subject to shoreline standards and critical areas standards pursuant to FWRC 15.10.160, and may be approved by the director only if no reasonable alternative exists and if the proposal will not lead to or create any increased slide, seismic, or erosion hazard. The applicant submitted a Geotechnical Report, prepared by GeoResources, dated September 1, 2016 and revised September 15, 2016, for the proposed H-pile retaining wall along the top of the slope. The City's geotechnical consultant GeoDesign Inc. provided peer review of the report and prepared a Technical Memorandum dated September 29, 2016. GeoResources submitted a revised report on October 4, 2016, and an Addendum dated October 11, 2016. Based on the resubmitted reports all comments have been adequately addressed and the geotechnical documents conform to FWRC Chapter 15.10, Critical Areas. Per GeoDesign's recommendation, gravel must be placed at the end of the perforated pipe to protect ground surface behind bulkhead. ■ Tree Removal The applicant has requested that a large Fir tree be removed from the top of the bluff slope in the south portion of the wall area. This tree is known as the "eagle" tree as there is a known bald eagle nest in the tree. Based on the geotechnical report, the tree must be removed to provide adequate access for the construction equipment and construction of the wall. GeoDesign concurs with the tree removal request. The tree has a noticeable lean in the down slope direction and is along the edge of the area being impacted by the ground deformations. The owners have obtained a permit from U.S. Fish and Wildlife Service to remove the tree as it is a hazard. Per the August 26, 2016, Federal Fish and Wildlife Permit approval the owners are approved to destroy one bald eagle nest. CONDITIONS OF APPROVAL — SHORELINE EXEMPTION 1. In the event that any ground -disturbing activities or other project activities related to this development uncovers protected cultural material (e.g., bones, shell, antler, horn, or stone tools) an Inadvertent Archaeological and Historic Resources Discovery Plan must be implemented, see attached. 2. GeoResources must be on site during construction to monitor slope stability conditions and confirm construction activities do not adversely affect site stability. 3. A letter, prepared by GeoResources, verifying construction of the wall is in compliance with recommendations of the geotechnical report must be submitted to the City no later than 30 days after the walls have been fmalled. 4. An as -built survey of the retaining wall is required to be submitted to the City after the wall is constructed. This will provide baseline data for monitoring any long-term movement of the wall. 5. Gravel must be placed at the end of the perforated pipe to protect ground surface behind bulkhead. Prepared by: Becky Chapin, Associate Planner Date: November 21, 2016 COMMUNITY & ECONOMIC DEVELOPMENT DEPARTMENT RECEIVED 33325 8`h Avenue South 41k Federal Way, WA 98003-6325 CITY OF S E P 0 2 2016 253-835-2607; Fax 253-835-2609 Fed a ra I Way �.ci offederalwa .com CITY OF FEDERAL WAY CDS SHORELINE SUBSTANTIAL DEVELOPMENT PERMIT EXEMPTION APPLICATION File # 16 —/0 Y3 & (/—'s H - To BE COMPLETED BY APPLICANT Project Name: E I lib 4-. Pas ► t P-- - Z Project Address: �J �� S W r)a,,Sln Poi vL InM 98 2 3 Applicant: 67•fe a§ [ C Lt* C Mailing Address: 5'004 F0 h t U Phone Number: )1 E-mail: brGtGi b [�" AFL o_r�SoUr�� _ Description of Project: bVi� I_A b, 't Meets the criteria for exemption under which section of* WAC 173-27-040:_ *WashinatowAdrniniStrative Code online: ayl3s.lei.wa.Qov / D e Bulletin #143 —March 25, 2013 1 of 2 k:\Handouts\Shoreline Exemption TO BE COMPLETED BY STAFF 1) The proposed development is consistent with Section 2 of WAC 173-27-040 and is therefore exempt from the Substantial Development Permit Process. Yes ❑ No (explanatory narrative attached) 2) Proposal requires: Yes No ❑ Shoreline Variance ❑ C,�, Shoreline Conditional Use ❑ Review, Approval or Permit by other State or Federal Agency Fe,(mt-Y 3) Proposal complies with applicable provisions of the City's Shoreline Master Program. Yes ❑ No Condition(s) attached: �� Yes ❑ No 4) In accordance with FWRC Section 15.05.130, this application is hereby: Approved ❑ Denied lI 21 /6 Director, Community Development Department Da e Distribution: G Applicant X Owner .r File ❑ Outside Agency Bulletin #143 —March 25, 2013 2 of 2 k:\Handouts\Shoreline Exemption MDESIGNZ- Geotechnical I Environmental I Geological I Mining I Pavement 15575 SW Sequoia Parkway Suite 100 Portland, OR 97224 Off 503.968.8787 City of Federal Way Becky Chapin 33325 8th Avenue South Federal Way, WA 98003-6325 Professional Services Rendered Through October 28, 2016 01-Geotechnical Consultation - Peer Review Professional Personnel Principal Project Assistant Support Staff Invoice Summary Description RECEIVFF ' COMMUNITY & E�JNOMIC DEVELOPMENT DEPARTMENT OCT 3 12016 �\- . P-L '1'�10 Invoice number 1610-196 Date 10/28/2016 Project FederalWay-6-01 Elliott Residence - Slope Failure Mitigation Project Manager: Kevin J. Lamb Project Administrator: Kellie M. Stratton Billed Hours Rate Amount 11.00 184.00 2,024.00 1.35 74.00 99.90 0.09 70.00 6.30 Professional Personnel subtotal 12.44 2,130.20 Phase subtotal 2,130.20 Current Prior Billed Billed Invoice total 2,130.20 Total Contract Billed Amount Remaining 01-Geotechnical Consultation - Peer Review 2,130.20 0.00 2,130.20 2,130.00 -0.20 Total 2,130.20 0.00 2,130.20 2,130.00 -0.20 Aging Summary Invoice Number Invoice Date Outstanding Current Over 30 Over 60 Over 90 Over 120 1610-196 10/28/2016 2,130.20 Total 2,130.20 2,130.20 2,130.20 0.00 0.00 0.00 0.00 Payment is due upon receipt of invoice. To pay by credit card, please contact our accounting department at 503.968.8787. Page 1 We,DESIGN= September 29, 2016 City of Federal Way Department of Comn 33325 8`h Avenue Soy... Federal Way, WA 98003 Attention: Becky Chapin, Associate Planner Geotechnical Consultation - Peer Review Elliot Residence - Slope Failure Mitigation 3500 SW Dash Point Way Federal Way, Washington File#16-104364-00-SH GeoDesign Project: FederalWay-6-01 INTRODUCTION This letter presents a summary of our peer review of the geotechnical reports and background information regarding the proposed slope failure repair on the Elliot property at 3500 SW Dash Point Road in Federal Way, Washington. Our scope of services is to provide third parry review of the submitted geotechnical information, reports, and proposed construction plans for conformance with: Chapter FWRC 15.10 Critical Areas WRC 15.10.160 Limitations Geotechnical Report FWRC 1 5.05.040 General Development Standards (1) Impact Mitigation and Section (4)(b)(iii) addressing setback with regards to shoreline stabilization UNDERSTANDING The Elliott residence is waterfront property that overlooks Dumas Bay in Puget Sound. The residence is situated on a relatively level bench that extends along the eastern portion of the property from Dash Point Road to the top of the marine bluff slope above the shoreline. Beyond the residence the northern portion of the property slopes down and into the tidelands of Dumas Bay. The western portion of the property slopes down to,Joe's Creek that extends through the southwest corner of the property. The slope down to Dumas Bay is steep with a change in elevation of approximately 70 feet, and an inclination generally in excess of 1 H:1 V (1 horizontal to 1 vertical). The southern portion of 10700 Meridian Avenue North, Suite 402 1 Seattle, WA 98133 1 206.838.9900 www.geodesigninc.com the property slopes down to joe's Creek at an approximate 2H:1 V slope. An alluvial fan is present at the mouth of the creek where it enters Dumas Bay west of the property. The property contains Shorelands as defined in the FWRC and is categorized as Shoreline Residential Environment. FWRC Chapter 15.05 is applicable to this site as it meets the definition of Shorelands. The steep slopes on the north and west sides of the property are in excess of 40 percent and appear to meet the FWRC 15.05.030 Steep Slope Hazard Area definition and the FWRC 19.05.070 Landslide Hazard definition. We understand that a landslide occurred on the north side of the property last winter that has impacted both the Elliott property and the property to the north. The majority of the slope failure appears to be on the adjacent property to the north, which is owned by the City of Federal Way (City). South of the main slide area the area along the top of the slope adjacent to the Elliott house appears to have settled or slid down approximately 6 to 8 feet, and its relation to the main slide to the north is unclear. Mitigation of the slope deformation and slide impacts is necessary to protect the Elliott residence. A cantilever pile shoring wall is being proposed by the applicant as the preferred mitigation option. Portions of the existing deck at the rear of the house will be temporarily removed and reconstructed to facilitate installation of the soldier piles. DOCUMENT REVIEW As part of our scope of services, we reviewed the following documents: • Geotechnical Report and Geologic Hazard Assessment (dated September 1, 2016) prepared by GeoResources, LLC Geotechnical Report and Geologic Hazard Assessment (revised date September 15, 2016) prepared by GeoResources, LLC Structural Calculations (dated August 26, 2016) prepared by A. Blaze Bresko Site Plan (dated September 2016) prepared by GeoResources, LLC Federal Fish and Wildlife Permit, Eagle Nest Take, dated September 1, 2016 We also reviewed several site photographs provided by the Elliott to document some of the existing conditions We also visited to observe the existing conditions and proposed wall location. SITE VISIT OBSERVATIONS We visited the site on September 27, 2016 and met with Tom and Gloria Elliott, who provided access to the site and a general history of the slide events. There appear to be two failure areas along the marine bluff slope. The main slide area extends from the City property southwards on to a small portion of the Elliott property. The majority of the slide area is on the adjacent property with approximately the southern 10 to 20 feet, extending onto the Elliott property. The main slide area is approximately 50 to 60 feet in width and extends from the top of the slope down to the beach area. Bare soil is Me DESIGN= 2 Federa[Way-6-01:092916 exposed in the slide scarp. No springs or groundwater seeps were observed in the scarp area. The slide appears to surficial in nature and does not appear to be deep seated. Along the shoreline is a segmental concrete block bulkhead. The bulkhead has been buried by slide debris in the area below the main slide. The concrete block bulkhead is exposed east and west of where it is covered with slide debris. The toe of the slope behind and above the bulkhead has been undercut and eroded by wave action overtopping the bulkhead. Potential causative factors of the main slide are undercutting of the toe of the slope by wave action and saturated soil conditions. The secondary ground deformation or "slide" area is located south of the main slide and extends along the top of the slope beyond the east and west ends of the deck area at the back of the Elliott house. In this area the ground surface along the top of the slope appears to have settled or "dropped" several feet. The ground deformation appears to have occurred slowly as the area is still vegetated and no distinct bare soil indicating a rapid slide event is exposed on the slope. The Elliott's recalled a small tree that they seasonally pruned used to be located near the top of the slope but was now approximately 8 feet below it. The deformation along the deck area appears to be confined to the upper portion of the slope as no ground deformation, uprooted or leaning tress, or soil toe bulges are present along the toe of the slope behind the bulkhead. The large trees at the toe of the slope below the secondary "slide" feature appear to be vertically oriented. We probed the ground surface along the top of the slope, below the deck, and generally encountered very loose soil conditions, indicating possibly loose native fill placed during site grading activities for the house. The probe consisted of a steel probe rod 42 inches long that was able to be pushed its entire length into the soil at several locations, with very little effort. The Elliotts indicated that the northernmost roof drain at the back of the house is not tied in to a collection system and discharges out towards the top of the slope. The remaining roof drains are tied into a system that discharges down the slope on the west side of the property. The ground surface below the deck area is sloped towards the top of the slope. There is a large fir tree at the top of the slope near the southwest corner of the deck. The tree is referred to as the "eagle" tree. The tree has a noticeable lean in the down slope direction and is within and along the edge of the area being impacted by the ground deformation. We understand that the Elliott's have obtained a permit from WDFW to remove the tree as it is a hazard. REVIEW COMMENTS CHAPTER FWRC 15.10 CRITICAL AREAS Pertinent sections of FWRC Chapter 15.10 applicable to the geotechnical aspects of the project are 1 5.10.120 and 15.10.160. FWRC 15.10.120 RESPONSIBILITY OF APPLICANT The proposed location of the shoring wall appears to be generally indicated along the top of the slope on the submitted site plan. According to the Elliotts, the existing deck will be removed and COW DESIGN= 3 FederalWay-6-01:092916 the shoring wall will be installed behind the top of the slope adjacent to the scarp. The wall location will be within the area impacted by past grading and landscaping activities within the steep islope `hazard area. The eagle tree will also be removed as part of the work as a proactive measure, since it is located at the top of the slope and leaning downhill. The walls, if constructed properly, and removal of the tree should reduce the slide and ground deformation potential, improve local slope stability, and minimize impacts to the area. We conclude the proposed work is in compliance with FWRC 15.10.120. FWRC 15.10.160 LIMITATIONS The proposed wall location is within 25 feet of a geologically hazardous area. Based on the site constraints and existing development, there is no reasonable alternative to stabilize the slope area outside of the 25-foot buffer identified in FWRC 15.10.160 Limitations. As indicated in the GeoResources geotechnical report, construction of the wall with appropriate best management practice (BMP) elements will not lead to or create any increased slide or erosion hazards. The information provided in the GeoResources geotechnical report appears to reference FWRC requirements that have been since been revised. The report should be modified to conform with the updated code. Additional information or revisions to the geotechnical report are required and are identified below: • FWRC codes, referring to FWRC Chapter 19 should be revised to acknowledge that FWRC Chapter 15.05 is applicable to this site and that the site has a "Steep Slope Hazard" in accordance with FWRC 15.05.030. The report indicates that site does not meet the FWRC 19.05.070 definition of a Landslide Hazard Area. The site contains an existing slide and is subject to being undercut by wave action. Please update the report to reflect the existing conditions and that it meets the classification requirements for a Landslide Hazard area. • A recommended allowable equivalent fluid pressure of 275 pounds per square foot is provided to estimate the passive resistance in front of the wall, along with the recommendation to neglect the upper 4 feet of soil. This equivalent fluid density value appears to be representative of intact, undisturbed, medium dense to dense granular material. Based on the site plan, the proposed wall appears to be located at the top of the slope. The material below the top of the slope, a large portion of which is being relied upon for passive resistance, consists of very loose slide debris or fill that has settled and sloughed down slope and is steeply inclined. Please provide a revised passive pressure reflective of the existing conditions, or a recommended wall setback from the top of the slope criteria. • The initial report dated September 1, 2016 recommended a pile embedment depth of 5 feet into the Lawton Clay. This was revised in the September 16, 2016 report to what appears to be a 1-foot embedment for pile lengths of 25 feet. The material in front of the wall is loose slide debris and will remain susceptible to sloughing. A 1-foot penetration into the Lawton Clay seems insufficient without tieback elements. • Identify where deadman piles will be required and provide a recommended setback distance from the face of the wall or alternatively provide recommendations for soil tieback anchors of soil nails. XR DESI G N= 4 FederalWay-6-01:092916 • Lagging is recommended to be installed 3 feet below the existing grade in front of the wall, indicating that the actual wall height will be greater than the initial exposed wall height when completed. Update design drawings and calculations to reflect revised engineering recommendations. Identify extent of excavation required in front of the proposed wall, and identify how the ground disturbance will be mitigated. • Surface water drainage is identified as a causative factor for the failure to the north, please provide recommendations to address surface water drainage from the roof and deck area at the top of the slope. FWRC 15.05.040 (1) IMPACT MITIGATION (a) To the extent the Washington State Environmental Policy Act of 1971 (SEPA), Chapter 43.21 C RCW, is applicable, the analysis of environmental impacts from proposed shoreline uses or developments shall be conducted consistent with the rules implementing SEPA (FWRC 14.05.010 and Chapter 197- I 1 WAC). Mitigation for adverse impacts to shoreline functions will be triggered during the SEPA review, shoreline land use permit process, or exemption approval process. Installation of the proposed shoring wall and removal of the eagle tree is not anticipated to have a significant impact on the shoreline environment. GeoResources has recommended that the repair be completed immediately to prevent property damage. The failure is within approximately 6 feet of the deck foundations, and we agree that the area should be stabilized as soon as possible. Short-term impacts associated with the construction activity are expected to be limited to ground disturbance along the wall alignment and a narrow area in front of the wall where excavation to install lagging is necessary. We agree that the impacts can be mitigated through the proper planning and installation of appropriate temporary erosion and sedimentation control BMPs as recommended in the geotechnical report. FWRC 15.05.040 GENERAL DEVELOPMENT STANDARDS (4)(b)(iii) (iii) New development on sites with steep slopes and bluffs is required to be set back sufficiently to ensure that shoreline stabilization is unlikely to be necessary during the life of the project as demonstrated by a geotechnical analysis This section of the code requires sufficient setback to ensure that shoreline stabilization is unlikely to be necessary in the future to protect new development. The proposed wall is to protect existing structures on the site, and there is an existing concrete bulkhead along the shoreline. The area between the top of the slope and the existing house/deck is narrow and limits the available setback from the environmental critical area and the existing bulkhead/ ordinary high water mark. The proposed shoring wall location at the top of the slope appears to maximize the available setback from the shoreline while also protecting the existing improvements. FWRC 15.05.050 SHORELINE MODIFICATIONS We observed that the existing bulkhead along the shoreline is being overtopped and allowing the toe of the slope to be undercut by wave action. Continued undercutting and erosion along the slope will decrease slope stability and may adversely impact the existing improvements at the r-UDESIGN`' 5 Fed eralWay-6-01:092916 top of the slope. We understand the applicant may address the bulkhead repair at a later date and recommend that they engage their geotechnical engineer to address the information requirements identified in FWRC 15:05:050. FWRC 15.05.80 The proposed wall is classified as an Accessory Structure (FWRC 19. 05.190) and is permitted within the 50-foot shoreline setback as defined in FWRC15.05.80. Accessory Structures within the shoreline setback are limited to 8 feet in height and any one structure covering less than 150 square foot and no more than 300 square foot combined coverage. We estimated the wall footprint coverage as the width of a typical shoring wall (approximately 1 foot) times the length of the wall (estimated to be approximately 80 feet); the proposed wall within the 50-foot setback has an estimated coverage of approximately 80 square foot and is in accordance with the code. The exposed height of the wall is identified as 8 feet that is consistent with the code. We appreciate the opportunity to provide our services on this project. Please call if you have questions regarding this submittal. Sincerely, GeoDesign, Inc. Kev-sn J. l_ b, P.E. Principal Engineer KJL:rc One copy submitted (via email only) Document ID: FederalWay-6-01-092916-geol.docx © 2016 GeoDesign, Inc. All rights reserved. PIP i 1 L G. �t ?Saat vp ii L41 ONAL�'�`' Signed 09/29/2016 MeDESIGN-K 6 FederalWay-6-01:092916 RESUBMIT -FED �p DEPARTMENT OF CONINIUNITY DEVELOPMENT SERVICES ICES U B M I' FE ® 33325 8`h Avenue South Federal Way, WA 98003-6325 CITY OF 253-835-2607; Fax 253-835-2609 ,���.cit,:offedera►�vaY.co,n Federal Way OCT x 1 zo,6 w C—X Y OF FEDEPAL WAY CDS RESUBMITTAL INFORMATION This completed form MUS T accompany all resubmittals. "Pleasenote.- Additional or revised plans or documents for an active project will not be accepted unless accompanied by this completed form. Mailed resubmittals that do not include this form or that do not contain the correct number of copies will be returned or discarded. You are encouraged to submit all items in person and to contact the Permit Counter prior to submitting if you are not sure about the number of copies required. ** ANY CHANGES TO DRAWINGS MUST BE CLOUDED. Project Number: Project Name: Project Address: l_11 °�' �L `� SJl- r Project Contact: V S Phone: �--A -3`P RESUBMITTED ITEMS: # of Copies ** Detailed Description of Item 3 = o - c' •� ��vc�7-�c� ' - oi• G — Always submit the same number of copies as required foryour initial application." Resubmittal Requested by: &4Letter Dated: I 1 Nan em V OFFICE USE ONL Y RESUB A Distribution Date: 0 Dept/Div Name # escription uildin Plannin PW Fire Other Bulletin #129 -January 1, 2011 Page I of 1 k:\Handouts\Resubmittal Information RE S U B M I17ia DEPARTMENT OF COMMUNITY DEVELOPMENT SERVICES 33325 8`h Avenue South Federal Way, WA 98003-6325 CITY OF S E P 21 2016 253-835-2607; Fax 253-835-2609 Federal WayCITY OF FEDERAL WAY www.cityoffederalway.com CDS RESUBMITTAL INFORMATION This completed form MUST accompany all resubmittals. **Please note: Additional or revised plans or documents for an active project will not be accepted unless accompanied by this completed form. Mailed resubmittals that do not include this form or that do not contain the correct number of copies will be returned or discarded. You are encouraged to submit all items in person and to contact the Permit Counter prior to submitting if you are not sure about the number of copies required. ** ANY CHANGES TO DRAWINGS MUST BE CLOUDED. Project Number: _L __0 - I 0 Project Name: E «� a Project Address: Project Contact: Phone: RESUBMITTED ITEMS: # of Copies ** Detailed Description of Item e�•� va L I. ►{ 1 O r73� "** Always submit the same number of copies as req& red for your initial application."" Resubmittal Requested by: �� Letter Dated: �q/ Iq !14, ` (Stan er Cew�a � I) OFFICE USE Oft Y RESUB #.•�_ Distribution Date: By' Dept/Div Name # Description Building . Planning PW Fire Other Bulletin #129 —January 1, 2011 Page 1 of 1 k:\iandouts\Resubmittal Information Ph.253.896-1011 Fx.253-896-2633 Tom and Gloria Elliott 3500 SW Dash Point Rd. Federal Way, WA 98023 (253) 350-7980 GeoResutirces, LLC 5007 Pacific Hwy E, Suite 16 Fife, Washington 98424-2649 October 11, 2016 Geotechnical Report and Geologic Hazard Assessment - Addendum Slope Repair - H-Pile Wall 3500 Dash Point Rd. Federal Way, Washington PN: 6613500011 Doc ID: Elliots.Dash PtRd.RGA This report addendum provides additional information related to the recent landslide and subsequent slope movement observed on October 10, 216. Attached please find a site sketch illustrating the general site configuration and the new ground rupture identified at the northwest portion of the site. Based on our discussions at the site, it is likely that this new ground rupture followed the rainfall last week. It is obvious that the stability of the slope area near the bluff is marginal at best, and immediate action is require to protect the residence. In particular, following the discovery of the foundation elements being conventional with no deepened support. As noted in the GeoDesign letter, the soils near the top of the slope are in a loose condition. Based on our site observations and subsurface exploration, these soils are not fill, but recessional sands. Much of the soils near the surface and in particular around the large trees has been disturbed through weathering. Probing in this area does indicate the loose weathered condition. To that point, probing in the area of the new ground rupture shows little or no resistance to even greater depths. The new rupture was observed to be as wide as 4 inches below the surface vegetation. It will not be necessary to monitor and likely install needle piling to provide adequate support for the deck supports in the northwest portion of the deck. This can be accomplished by McDowell, your contractor, at the same time as the wall if necessary, or at a later date based on monitoring results. We strongly recommend that the failing slope adjacent to the residence be treated as an emergency and installation of the retaining wall be initiated and completed as soon as possible. Obviously this requires the immediate removal of the timber deck and eagle tree to provide adequate access for the construction equipment. Temporary erosion control measures will be installed concurrently, and permanent measures installed as soon as practical following completion of the wall. Elliot — Dash Point Rd October 11, 2016 Page 2 Please contact us if you need additional information or have any questions. We look forward to working with you on this project. Respectfully submitted by, GeoResources, LLC Brad P. Biggerstaff, LEG, LHG, QE Principal BPB:DCB:bpb DocID: Elliot.DashPtDr.RGu Attachments: Figure 1: Deck Plan with Ground Rupture and Wall Location of ��c Dana C. Biggerstaff, PE Sr. Engineer Ph.253.896-1011 Fx.253-896-2633 Tom and Gloria Elliott 3500 SW Dash Point Rd. Federal Way, WA 98023 (253) 350-7980 GeoRe,s�-.,arces, LL{C 5007 Pacific Hwy E, Suite 16 Fife, Washington 98424-2649 RESUBMITTED OCT 11 2016 CITY OF FEDERAL WAY CDS September 1, 2016 September 15, 2016 Revision: October 4, 2016 Revised Geotechnical Report and Geologic Hazard Assessment Slope Repair - H-Pile Wall 3500 Dash Point Rd. Federal Way, Washington PN: 6613500011 Doc ID: Elliots.Dash PtRd.RG.REV3 INTRODUCTION This revised report summarizes our site area observations, discussions with you, data review, previous explorations by others, and our recent subsurface exploration, and our experience in the site area, and provides additional information requested by the City. We understand that following the significant rainfall in December of 2015, the adjoining property to the north experienced a slope failure on the shoreline bluff. Subsequently, the slide extended onto your property, resulting in a 6 to 8 foot drop along the top of the shoreline bluff on the northern portion of your property. Our evaluation was completed to provide geotechnical recommendations and design criteria for stabilization of that steep shoreline bluff area. Part of our evaluation included meeting with piling contractors to select your preferred slope stabilization option, an H-pile and timber lagging wall system. We understand that you would like to proceed with H-pile wall system, which will be provided by Pile King (McDowell NW). This report provides specific design information for this wall type. A structural engineer is providing the site specific wall design criteria, pile size and spacing. The site is located in the west portion of Federal Way, Washington and extends down to the waters of Puget Sound. The general location of the site is illustrated on the Site Location Map, Figure 1. Based on our discussions with you and our site observations, the failure was likely caused by the significant rainfall that occurred in December. The slide that occurred on the City of Federal Way property to the north extended to the shoreline area, and debris accumulated on the beach area. Shortly after that, you observed the upper north bluff area on your property had failed, dropping approximately 6 feet. That area has since settled another approximately 2 feet or more. The failure is approximately 45 feet wide at the top, extending to the north. The slide mass extends down the slope about 35 to 55 feet. The slide debris on the City property was observed to extend to the shoreline area, while the failure on your property extends to approximately mid slope. The failure extends into your rear yard/landscape area between 2 and 4 feet. The headscarp is about 4 to 6 feet from the rear deck supports and 11 to 16 feet from the residence. Vegetation remains in the disturbed area on your property, but is absent to the north. We expect that additional material will continue to move down slope, likely reactivating and accelerating next wet season. Continued movement of the slide mass is increasing the vertical Elliot— Dash Point Rd October 4, 2016 Page 2 height of the head scarp, increasing the risk to the residence. Subsequent to our original report, we determined that the house is on a conventional foundation (no deepened support/piles. Based on this, it is our opinion that the residence is at imminent risk of damage given the proximity and geometry of the slide. We recommend that the slope area be stabilized immediately. Recommendations for stabilization of the slide area are provided below. We also understand that because of the height and inclination of the slopes in the vicinity of the site, that a geologic hazard assessment is being required by the City of Federal Way Revised Code Chapter 19 and Chapter 15.05 (September 2016). We received review comments from GeoDesign dated September 30, 2016. The comments requested that our report be updated to discuss several items. The revised FWRC 15.05 code has been included. Chapter 15 (Section 05.030) is specific to shoreline areas, including a discussion/definition of critical areas, similar to Chapter 19 (Section 05.070). We have also updated sections of the report relative to landslide hazard criteria, revised passive pressure conditions, a discussion of pile embedment, the need for deadmen or tie backs, more detail regarding the limited excavation required in front of the proposed wall to install lagging, erosion mitigation of the potential disturbed area, and recommendations addressing surface water drainage from the roof and deck area at the top of the slope. Relative to erosion at the toe of the slope noted in the GeoDesign letter, we understand that you will likely apply for a permit to do soft armoring above the existing concrete block bulkhead to reduce the erosion that is occurring during significant storm events. This will be addressed in the future separately. SITE CONDITIONS The subject site is situated on a natural bench situated in the west margin of the Federal Way Upland area. According to the King County Assessor Website, the site is irregular in shape, measures 140 to 225 feet wide (northeast to southwest) by 295 to 475 feet deep (northwest to southeast), and encompasses approximately 1.61 acres. The site is bounded by a existing residential development on the south, Dumas Bay Centre on the north, Dash Point Road on the southeast, and the Puget Sound on the west. The ground surface at the site ranges from gently to steeply sloping, with the residence being constructed on a natural bench as a daylight basement type residence. Slopes in the upland area range from 5 to 20 percent. The west portion of the site steepens to between 40 and 120 percent. Total topographic relief across the site is on the order of 60 to 65 feet. A large fir tree, designated an Eagle Tree, is situated at the top of the bluff slope in the south portion of the wall area. We expect that this tree will need to be removed during wall installation. Based on the Federal Way Critical Area Code, the steeper portions of the site meet the technical criteria of landslide hazard and erosion hazard areas. The County View topography is included as Figure 2. The recent landslide initiated on the City property to the north, extending onto the subject site. The failure scarp occurred just below the top of the bluff slope, dropping a total of 8 to 12 feet at the time of our last site visit. The proposed retaining wall will be constructed above the failure area in an effort to retain the upland area and protect the existing residence and appurtenant structures. As indicated above, the head scarp is approximately 6 feet from the deck supports, and as close at 14 feet to the residence. Our review of the previous geotechnical work at the site for the construction of the residence indicates that the structure is founded on a conventional foundation, rather than deepened foundation elements as expected originally. It is therefore imperative that the retaining wall be constructed as soon as possible to mitigate the risk of damage to the structure during the coming wet weather conditions. Elliot — Dash Point Rd October 4, 2016 Page 3 Site Soils The USDA Natural Resource Conservation Service (NRCS) Web Soil Survey maps the southwest portion of the site area are as Alderwood and Kitsap soils (AkF). Soils in the majority of the site area are mapped as Indianola loamy sand (InC). The Alderwood and Kitsap soils are derived from glacial till and forms on slopes of 25 to 70 percent. These soils are listed as having a "moderate to severe" erosion hazard when exposed and are included in hydrologic soils group B. The Indianola soils are derived from sandy glacial outwash and form on slopes of 5 to 15 percent. These soils are listed as having a "moderate" erosion hazard when exposed and are included in hydrologic soils group A. A copy of the NRCS-SCS soils map is included as Figure 3. Site Geology The draft the Geologic Map of the Tacoma North 7.5-minute Quadrangle, Pierce County, Washington by Troost, K.G., Booth, D.B., and Borden, R.K. (in review) indicates that the site is underlain by Vashon recessional outwash (Qvrl,,) over advance outwash (Qva). These glacial soils were deposited during the most recent Vashon Stade of the Fraser Glaciation, approximately 12,000 to 15,000 years ago. The recessional and advance outwash soils consist of a poorly sorted, lightly stratified mixture of sand and gravel that may contain localized deposits of clay and slit that were deposited by meltwater emanating from the advancing and retreating ice mass, respectively. The recessional outwash is considered normally consolidated. Because the advance outwash was subsequently overridden by the glacial ice mass, it is considered overconsolidated and exhibits high strength and low compressibility characteristics. Based on the results of previous explorations, and our recent boring at the site, the soil profile consists of a veneer of recessional outwash sand and gravel over glacial till, and advance outwash sand at depth. These soils are underlain by silty lacustrine soils of the Lawton. A copy of the geologic map for the site area is included as Figure 4. The shoreline area at the site is mapped as intermediate and unstable on the Coastal Zone Atlas map, included as Figure 5. In general, the deeper glacial till and advance outwash deposits are glacially consolidated and typically in a very dense condition where undisturbed. However, the surficial recessional outwash soils, as well as the weathered surficial soils, are considered normally consolidated and in a loose to medium dense condition. Where the underlying soils are in a dense to very dense condition, this can result in a seasonal perched groundwater condition. We observed localized areas of seepage in the mid -slope area during our site visit, and expect that this is related to that zone, recessional over till. Subsurface Conditions Based on our review of the previous subsurface explorations and report prepared by AESI (1986) for the original building permit at the site, and the results of our recent boring, the site soils were observed to be somewhat different than the previously reported stratigraphy, recessional outwash over glacial till and advance outwash. Our boring encountered medium dense recessional outwash to a depth of approximately 16.5 feet bgs, 6 feet of medium dense to dense silty sand with gravel that we interpret to be glacial till, and several feet of medium dense to dense advance outwash. The soils were underlain by blue -gray silt from 24 feet to the full depth explored, likely the Lawton formation, a glacial lacustrine or lake deposit. We also observed that the majority of the granular soils encountered were in a medium dense to dense condition, with the deeper Lawton clay being in a very stiff to hard condition. The Lawton was encountered in our boring located in the southwest portion of the site, adjacent to the timber deck. The boring was terminated at 36.5 feet in the Lawton. A copy of the boring log and laboratory test results are included in Appendix "A". Elliot— Dash Point Rd October 4, 2016 Page 4 CONCLUSIONS AND RECOMMENDATIONS Based on our data review, site observations, previous and recent explorations and our experience in the area, it is our opinion that the slope failure at the site was the result of significant wet weather conditions during the last winter affecting shallow or surficial soils on the steep slope. Although the failure initiated on the property to the north, it extends onto the subject site. We expect that the failure was related to uncontrolled surface runoff and the resultant saturated ground conditions that followed the historic December 2015 rainfall levels. The large fir tree situated near the top of the slope will likely need to be removed for installation of the wall. We expect that the stump can remain in place with the wall being constructed around it, although that will be determined during construction. Geologic Hazards per Federal Way Revised Code The City of Federal Way Critical Areas Ordinance for Geologically Hazardous Areas (Chapters 15.05.030 and 15.10, and Chapters 19.05.070G and 19.160) state geologically hazardous areas shall mean areas that, because of their susceptibility to erosion, landsliding, seismic or other geological events, are not suited to siting commercial, residential or industrial development consistent with public health or safety concerns." The Revised Code of Federal Way is copied in italics, while our comments to the code are immediately following the code. Erosion Hazard Areas per Federal Way Revised Code The City of Federal Way code defines erosion hazard areas as "those areas having a "severe" or 'very severe" erosion hazard due to natural agents such as wind, rain, splash, frost action or stream flow." The USDA NRCS maps the soils on the upland area as Alderwood and Kitsap soils and Indianola soils which have a "Moderate to Severe" and "Moderate" erosion hazard. Based on the mapping, the site does not meet the technical definition of an Erosion Hazard area per the City code. Provided BMPs are in place prior to the start of earthwork activities at the site, the site poses a low risk to surrounding and adjacent properties from potential erosion hazards. Landslide Hazard Areas per Federal Way Revised Code The Federal Way City Code defines landslide hazard areas as "those areas potentially subject to episodic downslope movement of a mass of soil or rock including but not limited to the following areas: 1. Any area with a combination of. a. Slopes greater than 15 percent, b. Permeable sediment overlying a relatively impermeable sediment or bedrock; c. Springs or groundwater seeps. 2. Any area which has shown movement during the Holocene epoch, from 10,000 years ago to the present, or which is underlain by mass wastage debris of that epoch. 3. Areas potentially unstable as a result of rapid stream incision, stream bank erosion, and undercutting by wave action. 4. Areas located in a canyon or on an active alluvial fan, presently or potentially subject to inundation by debris flows or catastrophic flooding. 5. Areas that have a "severe" limitation for building site development because of slope conditions, according to the USDA SGS. 6. Those areas mapped as Class U (Unstable), Uos (Unstable old slides), and Urs (unstable recent slides) by the Department of Ecology. Elliot — Dash Point Rd October 4, 2016 Page 5 7. Slopes having a gradient steeper than 80 percent subject to rock fall during seismic shaking" The site has slopes steeper than 15 percent, but no adverse or intersecting contacts are mapped on the site. The weathered till/glacial till contact on upland areas typically does not constitute an adverse geologic contact, however there is potential for the recessional outwash and till to perch seasonal water. No seeps or springs noted on the site. No areas of mapped landslide debris or activity were noted on the published USGS geologic map. No areas of alluvial fans are mapped nor were any alluvial fans noted in the vicinity of the site at the time of our site visit. The site soils (AkF, InC) are listed as having a moderate to severe building limitations because of the slope. The site slopes are not steeper than 80 percent which are subject to rock fall during seismic shaking. The site is located on a shoreline and has shown movement within the last year but not due to wave action. The site is mapped by the DOE Coastal Atlas as "U" unstable along the northern shoreline.. Based on our field observations and experience with the soil types observed and mapped on the property, the site does have several of the above indicators. The upland site soils are generally stable relative to deep-seated failure in their present configuration. The recent failure is likely related to the natural process of weathered soils being saturated by the heavy winter rains (December (2015) and the related surface water runoff. Relative to the movement on the subject site, the loss of lateral support and downward movement from the north property likely contributed to the movement on the Elliott site. Given the recent movement, and the steep slopes on the shoreline bluff area, the site meets the technical definition of a landslide hazard area. However, given the access limitations of the site, it is necessary to install the retaining wall at the top of the slope to stabilize the site and protect the residence and appurtenant structures. Seismic Hazards per Federal Way Revised Code The City of Federal Way Municipal Code defines seismic hazard areas as "those areas subject to severe risk of earthquake damage as a result of seismically induced ground shaking, slope failure, settlement or soil liquefaction, or surface faulting. These conditions occur in areas underlain by cohesionless soils of low density usually in association with a shallow groundwater table." Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in pore water pressure. The increase in pore water pressure is induced by seismic vibrations. Liquefaction mainly affects geologically recent deposits of loose, fine-grained sands that are below the ground water table. Based on the density of the mapped soil types, it is our opinion that the risk for liquefaction to occur at this site during an earthquake is negligible. Provided the design criteria listed below are followed, the proposed structure will have no greater seismic risk damage than other appropriately design structures in the Puget Sound area. Lateral Earth Pressures For planning and design purposes, the following soils information may be utilized. This information is based on our site observations and experience in the site area, and the subsurface conditions encountered in our boring. The upper soils encountered (slope area) consist of silty sand with gravel and occasional cobbles and boulders. These soils are in a medium dense condition. The upper portion of these soils is weathered to a loose to medium dense condition, about 3 to 5 feet in depth. Below these shallow soils, medium dense silty sand and sand with silt was encountered to a depth 15 feet bgs. Below this depth, approximately 6 feet of medium dense to dense sandy silt with gravel (glacial till) and about 2 to 3 feet of medium dense to dense sand with silt and gravel Elliot— Dash Point Rd October 4, 2016 Page 6 (advance outwash) was encountered. Below a depth of approximately 24 feet, Lawton clay was encountered to the full depth explored, 36.5 feet. All of the site soils were observed to be in a damp to wet condition. Active lateral earth pressures for these soils may be assumed to be 40 pcf, provided they are not sloping and groundwater is not present. This pressure assumes the wall can move at least 0,001 *H in order to develop active pressures. If structural geofoam backfill is used with a 1 HA V wedge from the bottom of the exposed face of the wall, an active lateral earth pressure of 5 pcf is appropriate, in our opinion. Passive resistance from the upper 4 feet of the soils on the slope should be ignored. It should be noted that the McDowell design incorporates an exposed wall (beam) height of 4 feet plus the upper 4 feet of potentially disturbed soils, an effective stickup of 8 feet. Below this an allowable passive earth pressure of 275 pcf may be used. This value was reduced to account for the slope in front of the wall and the loose soil material. We recommend this pressure be applied over twice the pile width. A seismic surcharge of 8*H should be used to account for the live load during the 975 year return period design earthquake based on the Mononabe-Okabe analysis. Soldier Piling Based on our site observations, we understand that site access is limited and that a driven H-pile wall (with timber lagging) is preferred. A driven soldier pile wall consists of steel H-piles or beams driven into the underlying soils to the recommended depth. After the pilings are installed, treated timber lagging, consisting of treated timber or pre -cast concrete panels are placed between the H-piles and provide lateral support. Given existing site grades, exposed wall heights may reach 4 feet with an addition 4 feet of 4 feet of disturbed soil being ignored relative to passive earth pressure. Based on our on -site discussions with the piling contractor and the structural engineer, cantilevered piles are feasible using a spacing of 4 feet on center with a W8X24 piles located along the top of the slope. The proposed pile length is 25 feet with the top elevation of the pile being at or just below the ground surface at the top of the slope. This will allow the installation of a fence if desired. To account for arching effects, lateral loading on the timber lagging can be reduced by 50 percent. Voids behind the lagging, expected to be minamal, should be filled with clean sand or drainage material such as sand and gravel, or structural foam and pea gravel. Specific criteria for structural foam can be provided based on the site conditions at your request. The native soils may be suitable for reuse as backfill material for the upper one foot behind the wall. Passive resistance from soil should be ignored in the upper 3 to 5 feet where there is a slope up to 3H:1 V below the toe of the wall. This has been addressed by a structural engineer. The required depth of embedment must satisfy both lateral and vertical loading requirements. We recommend that soldier piles penetrate at least double the exposed wall height below the adjacent ground surface. Based on the geology at this site, we recommend that the piles be driven a minimum depth of 25 feet from the level of the bluff top, the location of the boring. This will provide adequate embedment into the very dense glacial till and advance outwash soils. These recommendations should be included in the bid documents. We understand that the piles have been upsized from 6-inch to 8-inch H-beams, and will be driven with a larger hammer than originally discussed at our site meeting and discussed previously. The larger piles will also have less than 8 feet of stick-up (including the upper soil zone), therefore "deadman" piles will not be needed, per the structural engineer. We recommend that timber lagging be installed between the piles where exposed. The timber lagging will be installed with the ends behind the beam flanges. Lagging should be installed to a minimum of 3 feet (measured vertically) below the existing grade, or exposed piles to minimize soil raveling. All disturbed areas should be erosion protected, including jute matting, mulch, seeding and/or hydroseeding. Elliot— Dash Point Rd October 4, 2016 Page 7 Typically, a geo-composite drainage material, such as Miradrain, is continuously placed on the exposed soil between the piles and connected to the drain pipe or weep drains at the base of the wall. Alternatively, the contractor may provide means, such as weep holes or %8 to 1/4-inch or a nap in lagging, to prevent the buildup of hydrostatic pressures behind lagging as necessary. A representative of GeoResources should be on site during the installation process to verify the pile tip reaches the minimum embedment into the lower, dense silty soils, and is consistent with conventional construction standards. Geofoam Backfill and Drainage Currently, the wall is planned to be located at the top of the slope, requiring little backf ill behind the wall lagging. We expect that minimal material may be required to fill the narrow void between the soil and the lagging. In the event more backfill is required than this, geofoam is recommended. Geofoam consists of expanded polystyrene with a unit weight ranging from 1 to 3 pounds per cubic foot. For this project type we typically recommend geofoam meeting the requirements of ASTM D 6817 Type EPS22, based on the deformation properties. In addition, if carpenter ants are likely to be present on site we recommend using geofoam that has been treated to prevent insect infestation. We recommend the geofoam blocks extend horizontally a distance equal to the slope height and vertically at least 5 feet below the finish grades. The geofoam blocks should be placed in a staggered pattern so that the joints between the blocks do not align with the underlying or overlying rows. Gaps between the geofoam blocks should be completely filled as the blocks are placed with a free draining, granular material, such as pea gravel. A minimum of 6-inches of drainage material should be placed on the slope behind the geofoam and below the lowest row of geofoam. The drainage material below the bottom row of geofoam blocks should be graded so that the blocks sit level and a perforated or slotted drain pipe could be placed at the bottom of the excavation if groundwater is encountered. If a drain is required it should be conveyed to the same point as the other drains at the site. Where the perforated/slotted pipe connects to a tightline, a structure or check -dam should be utilized. Geofoam is subject to deterioration if exposed to petroleum products, such as gasoline or diesel fuel. We recommend that landscape maintenance equipment using these fuels not be allowed near areas of geofoam. During construction special care must be taken to avoid spilling fuel on the geofoam. A geotextile separator per WSDOT specification 9-33.2 could be placed over the geofoam to reduce the risk from spills. A minimum of 2-feet of separation should be maintained over the geofoam to the final grades where the blocks are below the yard. Small trees and shrubs with shallow root systems should be used as vegetation and irrigation should not be installed on or near the slope. A landscape professional should be consulted to recommend plant and a planting pattern. Slope Stability Based on our field observations and experience with the soil types observed and mapped on the property, the upland site soils are generally stable relative to deep-seated failure in their present configuration. The recent failure is related to the natural process of weathered soils being saturated by the winter rains and uncontrolled surface water runoff. Further, the loss of lateral support from the north property likely contributed to the movement on your site. The proposed retaining wall should stabilize the slopes at the site and allow for the remediation of the disturbed area. Proper planning, design and excavation techniques will reduce the risk of potential surficial erosion or movement in slope areas during site activities and future development. We recommend that the downspout lines for the residence be tightlined to the lower portion of the slope, or redirected to the south flatter portion of the site. Relative to the property to the north, Elliot — Dash Point Rd October 4, 2016 Page 8 this is owned by the City and stormwater controls should be verified and improved if necessary. Construction Considerations We recommend that we be called at the start of the pile installation to verify installation to the appropriate depths and spacing. We do not need to witness all of the piling, but do want to verify that conditions are as expected and that the piling are being installed as recommended. If you have questions, please call us. As previously indicated, the soils in the site area typically contain larger soil material (gravel, cobbles and boulders) as well as organic debris (roots). These materials can result in difficult driving conditions and the contractor should be prepared to deal with these if encountered. LIMITATIONS Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in this area at the time this report was prepared. Although subsurface explorations were completed for this evaluation, soil conditions can change significantly both horizontally and with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient monitoring, testing and consultation should be provided by our firm during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with contract plans and specifications. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or type of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. We hope this satisfies your current needs. ono Elliot— Dash Point Rd October 4, 2016 Page 9 Please contact us if you need additional information or have any questions. We look forward to working with you on this project. Respectfully submitted by, GeoResources, LLC M1t_ 401 rrr Brad P. Biggerstaff, LEG, LHG Principal Dana C. Biggerstaff, PE Sr. Engineer BPB:DCB%pb DocID: Elliot. Dash PtDr.RGa Attachments: Figure 1: Site Vicinity Map Figure 2a: Wall Location Aerial w/ Boring Location Figure 2b: Site Plan with Wall Location Figure 3: NRCS Soil Conservation Map Figure 4: Geologic Map Figure 5: Coastal Zone Atlas Appendix A: Soil Classification Table, Boring Log and Lab Test Results 39lrf� Dumas � Bay Park y Lt` l(bt a Gay Park - K Dumas Bay Centre � eh; r�• - �jl �-� Fry•,stiy � i��ec�ei al W y int s, -� irk _. sl. is Lake ' 3622, S �-�4i 5,7.Lake 185'OH2.;:�isGiss ? th R �y': Jeane 1 1�2 �` d. •; Lh INV r S 4 r ' I err �l&hst `� %. �' Y rn; fir_ - ---• Lakota Park '3LS� a 1 34.1 31?tli Po - I�i -1: 11' ''[' 315rh rn - T- 11 sarc 21 Approximate Site Location (Map created from King County Public GIS iMap) Not to Scale GeoResources, LLC Site Location Map 5007 Pacific Highway East, Suite 16 Proposed Slope Repair Fife, Washington 98424 3500 Dash Point Road Phone: 253-896-1011 Federal Way, Washington Fax: 253-896-2633 Doc ID: Elliott. DashPointRd. F June 2016 Figure 1 Approximate Site Location (Map created from King County Public GIS iMap) GeoResources3 LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: 253-896-1011 Fax: 253-896-2633 Site and Exploration Plan Proposed Slope Repair 3500 Dash Point Road Doc ID: Elliott.D Not to Scale Federal Way, Washington ashPointRd.F June 2016 Figure 2A F- Approximate Site Location An excerpt from the draft the Geologic Map of the Tacoma North 7.5-minute Quadrangle, Pierce County, Washington by Troost, K.G., Booth, D.B., and Borden, R.K. (in review) Qvrlc Qva Recessional lacustrine deposits coarse Advance outwash GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: 253-896-1011 Fax: 253-896-2633 USGS Geologic Map Proposed Slope Repair 3500 Dash Point Road Federal Way, Washington Doc ID: Elliott. Dash PointRd.F I June 2016 Not to Scale o Scale re 5 pi q! 1 i k SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP GROUP NAME SYMBOL GRAVEL CLEAN GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL GRAVEL COARSE GP POORLY -GRADED GRAVEL GRAINED More than 50% SOILS Of Coarse Fraction GRAVEL GM SILTY GRAVEL Retained on WITH FINES No. 4 Sieve i GC � CLAYEY GRAVEL SAND CLEAN SAND SW WELL -GRADED SAND, FINE TO COARSE SAND More than 50% Retained on No. 200 Sieve SP POORLY -GRADED SAND More than 50% Of Coarse Fraction SAND SM SILTY SAND Passes WITH FINES No. 4 Sieve SC CLAYEY SAND SILT AND CLAY INORGANIC ML SILT CL CLAY FINE GRAINED SOILS Liquid Limit Less than 50 ORGANIC OL ORGANIC SILT, ORGANIC CLAY SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT More than 50% Passes CH CLAY OF HIGH PLASTICITY, FAT CLAY No. 200 Sieve Liquid Limit 50 or more ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT PEAT NOTES: SOIL MOISTURE MODIFIERS: 1. Field classification is based on visual examination of soil Dry- Absence of moisture, dry to the touch in general accordance with ASTM D2488-90. Moist- Damp, but no visible water 2. Soil classification using laboratory tests is based on ASTM D2487-90. Wet- Visible free water or saturated, usually soil is obtained from below water table 3. Description of soil density or consistency are based on interpretation of blow count data, visual appearance of soils, and or test data. GeoResources, LLC 5007 Pacific Hwy. E, Ste 16 Fife, Washington 98424-2648 Ph. 253-896-1011 Fx. 253-896-2633 Sc IL CLASSIFICATION SYSTEM FIGURE A-1 TOTAL DEPTH: 36.5 DRILLING METHOD: HSA LOGGED BY: STM TOP (ELEVATION: DRILLING COMPANY: Boretec HAMMER TYPE: Cathead LATITUDE: DRILL RIG: RCT HAMMER WEIGHT: 140 pounds LONGITUDE: NOTES: TEST RESULTS Plastic Limit ILiquid Limit o o Q % Water Content • > o> SOIL DESCRIPTION RILLING DNOTES E E E% Fines (<0.075mm) o m U :3a, � rn w U) Penetration - ♦ (blows per foot) 10 20 30 40 50 0 Topsoil/rootzone :: . Brown gravelly(loose t medium dense, moist)(recessional outwash) 4 j iiiic ....... 4 it 4 5 Occasional cobbles and boulders per drillers p 2 11 11 - . 7 € is •.: 10 oorl graded sand with silt 3 i ii;o:iii:iiiii5 %;t+iiiii iiii iid i-io•:�i•i�i i'-'.i iiiii• 6 - - ii'['iGi S• i i¢i+Ii7--� ' -- - - - - 10 is idi-e<-i6 i ii.iiii '•S•i-isii>i %iE�.iipii>EfiE 15 ':' 17 6 4 :i; 15 16 Gra ish brown sandy SIL1' wit some graved Y ;;f;;. iii><Fi rr s (stiff, moist) € � iii 20 5 .: -..... s I 12 14 Tan fine sand with silt (medium dense, moist) i Blue -gray SILT (very sti to Hard, moist ... i'i' 25 (glaciolacustrine) s 6 13 - - 19 30 7 - - 7 d ds° i'i Eii • 12 . 13 NOTES Proposed Retaining Wall 1. Refer to log key for definition of symbols, abbreviations and codes 3500 Dash Point Rd Federal Way, WA 2. USCS designation is based on visual manual classification and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary LOG OF BORING B-1 4. N.E. = Not Encountered 5. ATD = At the Time of Drilling JOB: Elliot.DaShPOintRd sneer 1 of z GeoResources LLC I FIG. TOTAL DEPTH: 36.5 DRILLING METHOD: HSA LOGGED BY: STM TOP ELEVATION: DRILLING COMPANY: Boren,_ HAMMER TYPE: Cathead LATITUDE: DRILL RIG: RCT HAMMER WEIGHT: 140 pounds LONGITUDE: NOTES: TEST RESULTS Plastic Limit Liquid Limit DRILLING % Water Content 0 -E 0 C o> SOIL DESCRIPTION NOTES E E E % Fines (<0.075mm) 0 0 0 2 co CD W CU U) ca U) U) Penetration - A (blows per foot) 10 20 30 40 50 ........ ......... . 35— 8 . ......... . = =7 ....... ... 13 Bottom of Boring CompletedJuly 21, 2016 ....... .... 40— ....... ... . ......... ....... ......... .. ......... . ....... 45— ........ ......... ......... . .... ......... ...... . ........ �T :N;N ..... ..... ........ ...... ......... ...... ......... ...... N ......... ....... ......... 50— ... . .... ....... .. ......... ...... Z Z t ........ ..... ... ........ ..... ... .... T4 ..... 55— ....... .. 24 ;WVII; ......... ......... . ... ......... ... .... ......... ....... ... 60— ......... ....... . t t Iti I 1 ........ ...... ......... . . + ':11 Mt� ..... ......... ......... ........ ...... ......... ......... ... ......... ......... ... - . ....... ........ .... ... ..... .... --------- ... ......... .. ......... .. ... 651 . ......... ...... NOTES Proposed Retaining Wall 1. Refer to log key for definition of symbols, abbreviations and codes 3500 Dash Point Rd 2. LISCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary 4. N.E. = Not Encountered LOG OF BORING B-1 5. ATD = At the Time of Drilling JOB: Ell lot. Dash Poi ntRd Sheet 2 of 2 GeoResources.-UC FIG. m c 0 a� 3 a a� E 0 0 c m 0 N 0 m m U x N a� 0 a) CIO U) m a� F- Particle Size distribution Report CE 000 100 90 80 70 Ir w Z 60 LL. Z 50 W U Ir 40 W rL 30 20 10 0 0 10 20 30 m DO 40 m Z 50 n O 60 :30 (n m 70 70 80 90 100 �anr llM a1LC -nun. LD % Gravel % Sand % Fines +3" Coarse Fine Coarse Medium Fine Silt Clay N0.0 0.0 2.0 7.1 39.9 40.4 10.6 TEST RESULTS Opening Percent Spec.* Pass? Size Finer (Percent) (X=Fail) .375 100.0 #4 98.0 #10 90.9 #20 79.0 #40 51.0 #60 23.8 #100 14.6 #200 10.6 (no specification provided) Source of Sample: B-1 Depth: 10 Sample Number: 3 GeoResources, LLC Fife, WA Material Description poorly graded sand with silt AtterbergLimits (ASTM D 4318) PL= LL= PI= Classification USCS (D 2487)= AASHTO (M 145)= Coefficients D90= 1.8074 D85= 1.1420� D60= 0.5073 D50= 0.4171 D30= 0.2891 D15= 0.1572 1310= Cu= Cc= Remarks Sample ID:092006 NM-7.6% Date Received: Date Tested: 8/2/16 Tested By: JPK Checked By: Title: Client: Tom Elliot Project: Proposed Retaining Wall Date Sampled: 7/21/16 Tested By: Checked By: a a) t 10C 9C 8C 7C Cc w Z 60 IL Z 50 W U 0= 40 w 30 20 10 0 Particle Size Distribution Report C C C C C S q 4 O O 00 N IN Mill I 1111011 HIM Diu � lid % +3" % Gravel Coarse IFine 0.0 0.0 1 0.0 GRAIN SIZE - mm. % Sand Darsel Medium I Fine 0.0 1 0.2 1 0.7 TEST RESULTS Opening Percent Spec.* Pass? Size Finer (Percent) (X=Fail) #10 100.0 #20 100.0 #40 99.8 #60 99.4 #100 99.2 #200 99.1 (no specification provided) Source of Sample: B-1 Depth: 30 Sample Number: 7 ° GeoResources, LLC ce Fife, WA % Fines Silt 99.1 Material Description Atterbera Limits (ASTM D 4318 D 10 eu 30 m M ao m z 50 0 s0 D) M 70 DO 60 90 100 PL= 23 LL= 43 PI= 20 Classification USCS (D 2487)= CL AASHTO (M 145)= A-7-6(22) Coefficients D90= D85= D60= D50= D30= D15= D10= Cu= Cc= Remarks Sample ID:092007 NM-26.8 Date Received: Date Tested: 8/2/16 Tested By: JPK Checked By: Title: Client: Tom Elliot Project: Proposed Retaining Wall Date Sampled: 7/21/16 Tested By: Checked By: _ 60 50 X 40 w z U 30 U) J a 20 ILI UQUID AND PLASTIC LIMITS TEST REPORT Dashed line indicates the approximate / upper limit boundary for natural soils-� G i i / / / / / / ML or OL MH or OH ^ 44.4 a% 44 H N 43.6 43.2 O .2 z 42.8 :- z ❑ OU 42.4 0�� W cC 42 O O 3 > 41.6 O U 15 41.2 U O 40.8 N G t ca 40. O LIQUID LIMIT NONE NNI�IINNNNI ONES ON - ONEENSINE MEMO ON ME MEN FINE mmommm oINON =0111111111111111111 N u NUMBER OF BLOWS 7 -may a) '�? MATERIAL DESCRIPTION LL PL m x s 43 23 a� F t co o0 m Project No. Elliot.DashPoin(Ribnt: Tom Elliot m Project: Proposed Retaining Wall c0 0 o Source of Sample: B-1 Depth: 30 m Sample Number: 7 a)CL CL GeoResources, LLC aD � -Fife, WA PI %<#40 %<#200 USCS 20 99.8 99.1 CL �—IRemarks: ure Tested By: JPK Checked By: 7TrQe l mac DEPARTNIENT OF THE INTERIOR ITso&WILDI"E U.S. FISH AND WILDLIFE SERVICE �IIVICE Z AUTHORITY -STATUTES Migratory Bird Permit Office 16 USC 668a 911 NE 11 th Ave. - Portland, OR 97232 Tel: 503-872-2715 Fax: 503-231-2019 Email: permitsRIMB rr fws,gov FEDERAL FISH AND WILDLIFE PERMIT REGULATIONS 50 CPR 13 1. PERNIITTEE 50 CFR 22.27 GLORIA G ELLIOTT 3500 SW DASH POINT ROAD FEDERAL. WAY, WA 98023 3. NUNIBF:R NIB03302C-0 U.S.A. d. RENEWABLE 5. MAY COPY YES YES NO NO 6. EFFECTIVE 7. EXPIRES 09/01/20 t 6 11 /302016 8. NAME AND TITLE OF PRINCIPAL OFFICER (trN 1 1s n business) 9. TYPE OF PERMIT EAGLE NEST TAKE - INACTIVE NEST 10. LOCATION WHERE AUTHORIZED ACTIVITY MAY BE CONDUCTED Physical location and records kept at: Address in block 1 (above) 47.327611,-122.377158 KING COUNTY, WA 11. CONDITIONS AND AUTHORIZATIONS: A. GENERAL CONDITIONS SET OUT IN SUBPART D OF 50 CFR 13, AND SPECIFIC CONDITIONS CONTAINED 1N FEDEIUAL REGULAI IONS CITED IN BLOCK A2 ABOVE, ARE HEREBY MADE APART OF THIS PERMIT. ALL ACTIVITIES AUTI IORIZED HEREIN MUST BE CARRIED OUT IN ACCORD WITH AND FOR THE PURPOSES DESCRIBED IN THE APPLICATION SUBMITTED, CONTINUED VALIDITY, OR RENEWAL, OF THIS PERMIT IS SUBJECT TO CONIPLETE AND TIMELY COMPLIANCE WITH ALL APPLICABLE CONDITIONS, INCLUDING THE FILING OF ALL REQUIRED 1NFORLVIATION AND REPORTS. B. THE VALIDITY OF THIS PERNIIT IS ALSO CONDITIONED UPON STRICT OBSERVANCE OF ALL APPLICABLE FOREIGN, STATE, LOCAL, TRIBAL, OR OTHER FEDERAL LAW. C VALID FOR USE BY PERMITTEE NANIED ABOVE D. To alleviate a'human health and safety emergency, you are authorized to: Destroy 1 bald eagle nest Location: 3500 SW Dash Point Rd, Federal Way, WA 98023 Activity Dates: 9/1/16 - 11/30/16 Reporting Required: 2016 E. This permit does not authorize lethal take or injury of eagles or eggs, nor does it authorize take of the nest in the event an eagle occupies the nest prior to nest destruction. F. You must comply with all avoidance, minimization, or other mitigation measures prescribed by the permit issuing office, including: 1) The nest must be removed outside the breeding season between Sept. 1, 2016 and Nov. 30, 2016 R E S U B M I17E D ® ADDITIONAL CONDITIONS AND AUTHORIZATIONS ALSO APPLY 12. REPORTING REQUIREMENTS SEP 2 1 2016 ANNUAL REPORT DUE: Within 10 days following completion of activities https:/Iwww.fws.gov/forms/3-202-16.pdf CITY OF FEDERAL WAY CDS ISSUED BY TITLE DATE HuoLl'2AL&_11Lk ' PERMIT SPECIALIST, MIGRATORY BIRD PERMIT OFFICE -REGION 1 08/26/2016 U G. During nest removal activity, you are authorized to salvage any eagle carcasses, feathers and parts including nonviable eggs found in or around the nest. All molted eagle feathers, parts, and carcasses found at the site must be shipped to the National Eagle Repository. Contact: U.S. Fish and Wildlife Service National Eagle and Wildlife Repository, Rocky Mountain Arsenal, Building 128, 6550 Gateway Road, Commerce City, Colorado, 80022, (303) 287-2110. Nonviable eagle eggs or nests or parts of nests must be destroyed by burial or incineration or donated to a qualified public educational or scientific institution as defined in 50 CFR 10.12 and approved by the your migratory bird permit issuing office. H. You may delegate the authority granted in this permit to the following subpermittee(s): None authorized. Any subpermittee who has been delegated this authority may not re -delegate to another individual/business. You must immediately notify the migratory bird permit issuing office in writing of any changes to subpermittee information so this permit can be amended to authorize those individuals/businesses. I. Subpermittees must be at least 18 years of age. You are responsible for ensuring that your subpermittees are qualified to perform the work and adhere to the terms of your permit. You are also responsible for maintaining current records of designated subpermittees. As the permittee, you are ultimately legally responsible for compliance with the terms and conditions of this permit and that responsibility may not be delegated. J. You and any subpermittees must carry a legible copy of this permit and display it upon request whenever exercising its authority. K. All of the provisions and conditions of the governing regulations at 50 CFR part 13 and 50 CFR 22.27 are conditions of your permit. Failure to comply with the conditions of your permit could be cause for suspension of the permit and/or citation. For copies of the regulations, visit: www.Nvs.,Qov/permits/mbpermits/birdbasics.html. L. You must submit a report of activities conducted under this permit to the migratory bird permit issuing office, 911 NE 11th Ave, Portland, OR 97232, within 10 days following completion of the activities or of the expiration of this permit, whichever occurs first. Form 3-202-16 (Eagle Nest Take Report) can be found online at www.fws.aov/formsl3-202-16.pdf <httg://www.fWs.gov/forms/3-202-16.pdf . M. This permit does not authorize you to conduct activities on Federal, State, or other public or private property without additional prior written permits or permission from the agency/landowner. N. You must maintain records as required in 50 CFR 13.46. All records relating to the permitted activities must be kept at the location indicated in writing by you to the migratory bird permit issuing office. O. Acceptance of this permit authorizes the U.S. Fish and Wildlife Service to inspect any wildlife held, and to audit or copy any permits, books or records required to be kept by the permit and governing regulations (50 CFR 13.46 and 50 CFR 22.27). P. You may not conduct the activities authorized by this permit if doing so would violate the laws of the applicable State, county, municipal or tribal government or any other applicable law. Q. The U.S. Fish and Wildlife Service is not liable for any damage or injury to person wildlife, or property that occurs as the result of carrying out the activities associated with this permit. DEPARTMENT OF THE INTEIUOR wn.>D1"e U.S. FISH AND WILDLIFE SERVICE F1W 9=VrC; Migratory Bird Permit Office 2 AUTHORITY -STATUTES 16 USC 668a 911 NE I 1 th Ave. - Portland, OR 97232 Tel: 503-872-2715 Fax: 503-231-2019 fws.gov Email: pei-initsR]MB@fws.gov nrY FEDERAL FISH AND WILDLIFE PERMIT REGULATIONS 50 CAR 13 L PERMITTEE 50 CPR 22.27 GLORIA G ELLIOTT 3500 SW DASH POINT ROAD FEDERAL WAY, WA 98023 3. NUMBER NIB03302C-0 U.S.A. 4. RENEWABLE 5. MAY COPS' YES YES ® NO NO 6• EFFECTIVE 7. EXPIRES 09/01/2016 11/30/2016 8_ NAME AND TITLE OF PRINCIPAL OFFICER (trMl l a beshieen) 9. TYPE OF PERMIT EAGLE NEST TAKE - INACTIVE NEST 10. LOCATION WHERE AUTHORIZED ACTIVITY MAY BE CONDUCTED Physical location and records kept at: Address in block 1 (above) 47.327611,-122.377158 KING COUNTY, WA 11. CONDITIONS AND AUTHORIZATIONS: A. GENERAL CONDITIONS SET OUT IN SUBPART D OF 50 CFR 13, AND SPECIFIC CONDITIONS CONTAINED IN FEDEILIL REGULATIONS CITED IN BLOCK 1l2 ABOVE, ARE HEREBY MADE A PART OF THIS PERMIT. ALLACTIVITIES AUTHORIZED HEREIN MUST BE CARRIED OUT IN ACCORD WITH AND FOR THE PURPOSES DESCRIBED IN THE APPLICATION SUBMITTED. CONTINUED VALIDITY, OR RENEWAL, OF THIS PERMIT IS SUBJECT TO COMPLETE AND TIMELY COMPLIANCE WITH ALL APPLICABLE CONDITIONS, INCLUDING THE FILING OF ALL REQUIRED INFORMATION AND REPORTS, B. THE VALIDITY OF THIS PERMIT IS ALSO CONDITIONED UPON STRICT OBSERVANCE OF ALLAPPLICABLE FOREIGN, STATE, LOCAL, TRIBAL, OR OTHER FEDERAL LAW. C. VALID FOR USE BY PERMTTTEE NAMED ABOVE D. To alleviate a human health and safety emergency, you are authorized to: Destroy 1 bald eagle nest Location: 3500 SW Dash Point Rd, Federal Way, WA 98023 Activity Dates: 9/1116 - 11/30/16 Reporting Required: 2016 E. This permit does not authorize lethal take or injury of eagles or eggs, nor does it authorize take of the nest in the event an eagle occupies the nest prior to nest destruction. F. You must comply with all avoidance, minimization, or other mitigation measures prescribed by the permit issuing office, including: 1) The nest must be removed outside the breeding season between Sept. 1, 2016 and Nov. 30, 2016 ® ADDITIONAL CONDITIONS AND AUTHORIZATIONS ALSO APPLY 12. REPORTING REQUIREMENTS ANNUAL REPORT DUE: Within 10 days following completion of activities https://www.fws.govlforms/3-202-16.pdf ISSUED BY TITLE DATE 0 -L, A PERMIT SPECIALIST, MIGRATORY BIRD PERMIT OFFICE - REGION 1 08/26/2016 u G. During nest removal activity, you are authorized to salvage any eagle carcasses, feathers and parts including nonviable eggs found in or around the nest. All molted eagle feathers, parts, and carcasses found at the site must be shipped to the National Eagle Repository. Contact: U.S. Fish and Wildlife Service National Eagle and Wildlife Repository, Rocky Mountain Arsenal, Building 128, 6550 Gateway Road, Commerce City, Colorado, 80022, (303) 287-2110. Nonviable eagle eggs or nests or parts of nests must be destroyed by burial or incineration or donated to a qualified public educational or scientific institution as defined in 50 CFR 10.12 and approved by the your migratory bird permit issuing office.. H. You may delegate the authority granted in this permit to the following subpermittee(s): None authorized. Any subpermittee who has been delegated this authority may not re -delegate to another individual/business. You must immediately notify the migratory bird permit issuing office in writing of any changes to subpermittee information so this permit can be amended to authorize those individuals/businesses. I. Subpermittees must be at least 18 years of age. You are responsible for ensuring that your subpermittees are qualified to perform the work and adhere to the terms of your permit. You are also responsible for maintaining current records of designated subpermittees. As the permittee, you are ultimately legally responsible for compliance with the terms and conditions of this permit and that responsibility may not be delegated. J. You and any subpermittees must carry a legible copy of this permit and display it upon request whenever exercising its authority. K. All of the provisions and conditions of the governing regulations at 50 CFR part 13 and 50 CFR 22.27 are conditions of your permit. Failure to comply with the conditions of your permit could be cause for suspension of the permit and/or citation. For copies of the regulations, visit: www.fws.goviperrnits/inbpermits/birdbasics.html. L. You must submit a report of activities conducted under this permit to the migratory bird permit issuing office, 911 NE 11th Ave, Portland, OR 97232, within 10 days following completion of the activities or of the expiration of this permit, whichever occurs first. Form 3-202-16 (Eagle Nest Take Report) can be found online at www.fws. ovlforms/3- 022-16. df <htt :/Iwww.fws. ovlforms/3-202-16. df>. M. This permit does not authorize you to conduct activities on Federal, State, or other public or private property without additional prior written permits or permission from the agency/landowner. N. You must maintain records as required in 50 CFR 13.46. All records relating to the permitted activities must be kept at the location indicated in writing by you to the migratory bird permit issuing office. O. Acceptance of this permit authorizes the U.S. Fish and Wildlife Service to inspect any wildlife held, and to audit or copy any permits, books or records required to be kept by the permit and governing regulations (50 CFR 13.46 and 50 CFR 22.27). P. You may not conduct the activities authorized by this permit if doing so would violate the laws of the applicable State, county, municipal or tribal government or any other applicable law. Q. The U.S. Fish and Wildlife Service is not liable for any damage or injury to person wildlife, or property that occurs as the result of carrying out the activities associated with this permit. A�kCITY OF Federal Way September 30, 2016 Brad Biggerstaff GeoResources, LLC 5007 Pacific Hwy East, Suite 16 Fife, WA 98424 bradb@georesources. its RE: File #16-104364-00-SH; GEOTECHNICAL CONSULTANT REVIEW Elliott Slope Repair, 3500 SW Dash Point Road, Federal Way Dear Mr. BiggerstafF. CITY HALL 33325 8th Avenue South Federal Way, WA 98003-6325 (253) 835-7000 www. cityoffederalway. com Jim Ferrell, Mayor GeoDesign Inc., the City's geotechnical consultant, has reviewed the Geotechnical Report, dated September 1, 2016, and revised September 15, 2016, prepared by GeoResources, in addition to the Structural Calculations, dated August 26, 2016, prepared by A. Blaze Bresko, for the development of the proposed H-pile retaining wall. GeoDesign's initial review has been completed. Enclosed please find the September 30, 2016, review comments from GeoDesign. Based on the review of the submitted information and review of the Federal Way Revised Code (FWRC), GeoDesign has identified specific issues and requirements that must be addressed prior to approval of the project. Please revise the report to address the comments made by GeoDesign. When resubmitting, please provide two copies of any revised plans or reports, accompanied by the enclosed Resubmittal Information form. I can be reached at 253-835-2641 or becky.chapin@cityoffederalway.com if you have any questions about this letter. Sincerely, v �[L Becky Cha in Associate Planner e: Mr. and Mrs. Elliott, 3500 SW Dash Point Road, Federal Way, WA 98023, tmelliott50@comeast.net, gloriaelliott0l@gmail.com — w/ enclosure enc: Resubmittal Information Form GeoDesign Inc. Technical Memo, dated September 30, 2016 Doc. LD. 74787 CITY OF `� Federal Way GEOTECHNICAL CONSULTANT AUTHORIZATION FORM Date: September 23, 2016 City: City of Federal Way Community Development Department 33325 8th Avenue South Federal Way, WA 98003 Consultant: Kevin Lamb GeoDesign, Inc. 10700 Meridian Avenue North, Suite 402 Seattle, WA 98133 (206) 838-9900 kl amb @geo des i gei n c. com Project: Elliot Slope Repair 3500 SW Dash Point Road Parcel #661350-0011 File No.: 16-104364-00-SH (Shoreline Substantial Development Exemption Permit) Project Proponent: Tom and Gloria Elliot 3500 SW Dash Point Road Federal Way, WA 98023 Project Proponent GeoResources LLC Geotechnical Brad Biggerstaff Consultant: 5007 Pacific Hwy East, Suite 16 Fife, WA 98424 253-896-1011 bradb @ eoresources.us Project Planner: Becky Chapin, Associate Planner becky.chapin @eityoffederalway.com 253-835-2641 Project Background: According to the city's critical areas map, the property contains erosion and landslide hazard areas. The proposed project is located within the "Urban Conservancy" shoreline designation. The applicant has submitted a geotechnical report and design plans for a proposed H-Pile Wall. The property is located along the top of a steep slope above the Puget Sound where landslides have occurred. The report addresses geotechnical design recommendations and design criteria for stabilization. Engineered wall plans have also been included. The applicant is also proposing to remove a tree where the wall is being placed. Documents • 6Qotechnical Report and Geologic Hazard M6,;ssment (dated September 1, Provided: 2016) prepared by GeoResources, LLC. ■ Geotechnical Report and Geologic Hazard Assessment (revised date September 15, 2016) prepared by GeoResources, LLC. • Structural Calculations (dated August 26, 2016) prepared by A. Blaze Bresko • Site Plan (dated September 2016) prepared by GeoResources, LLC. • Federal Fish and Wildlife Permit, Eagle Nest Take, September 1, 2016 Task Scope: 1. Review submitted documents for conformance to Federal Way Revised Code (FWRC) Chapter 15.10, Critical Areas, especially FWRC 15.10.160 and FWRC 15.05.040(4)(b) Geologically Hazardous Areas. (As this project is within the SMA jurisdiction, FWRC Chapter 15.10 applies instead of 19.145) 2. Discuss the proposed compliance with FWRC 15.05.040(i), 1M. pact mitigation. 3. Provide a memorandum identifying additional information requested as necessary. 4. Conduct site visit as necessary. 5. Provide written technical memorandums) regarding the proposal's conformance with FWRC. Task Cost: Not to exceed $ 2,130 without a prior written amendment to this Task Authorization. Acceptance: I City of FedVal Way 'J Date 09/23/2016 Consultant /GeoDesiRn, Inc. Date Geotechnical Consultant Authorization Form 2 Ph.253.896-1011 Fx.253-896-2633 Tom and Gloria Elliott 3500 SW Dash Point Rd. Federal Way, WA 98023 (253) 350-7980 Geodes _ urces, LLC 5007 Pacific Hwy E, Suite 16 Fife, Washington 98424-2649 September 1, 2016 September 15,2016 Geotechnical Report and Geologic Hazard Assessment Slope Repair - H-Pile Wall 3500 Dash Point Rd. Federal Way, Washington PN: 6613500011 Doc ID: Elliots.Dash PtRd.RG.REV2 INTRODUCTION This revised report summarizes our site area observations, discussions with you, data review, previous explorations by others, and our recent subsurface exploration, and our experience in the site area, and provides additional information requested by the City. We understand that following the significant rainfall in December of 2015, the adjoining property to the north experienced a slope failure on the shoreline bluff. Subsequently, the slide extended onto your property, resulting in a 6 to 8 foot drop along the top of the shoreline bluff on the northern portion of your property. Our evaluation was completed to provide geotechnical recommendations and design criteria for stabilization of that steep shoreline bluff area. Part of our evaluation included meeting with piling contractors to select your preferred slope stabilization option, an H-pile and timber lagging wall system. We understand that you would like to proceed with H-pile wall system, which will be provided by Pile King (McDowell NW). This report provides specific design information for this wall type. A structural engineer is providing the site specific wall design criteria, pile size and spacing. The site is located in the west portion of Federal Way, Washington and extends down to the waters of Puget Sound. The general location of the site is illustrated on the Site Location Map, Figure 1. Based on our discussions with you and our site observations, the failure was likely caused by the significant rainfall that occurred in December. The slide that occurred on the City of Federal Way property to the north extended to the shoreline area, and debris accumulated on the beach area. Shortly after that, you observed the upper north bluff area on your property had failed, dropping approximately 6 feet. That area has since settled another approximately 2 feet or more. The failure is approximately 45 feet wide at the top, extending to the north. The slide mass extends down the slope about 35 to 55 feet. The slide debris on the City property was observed to extend to -the shoreline area, while -the failure on your property extends to - - approximately mid slope. The failure extends into your rear yard/landscape area between 2 and 4 feet. The headscarp is about 4 to 6 feet from the rear deck supports and 11 to 16 feet from the residence. Vegetation remains in the disturbed area on your property, but is absent to the north. We expect that additional material will continue to move down slope, likely reactivating and accelerating next wet season. Continued movement of the slide mass is increaaag.thxe IGal SEP 21 2016 CITY OF FEDERAL WAY CDS Elliot — Dash Point Rd September 15, 2016 Page 2 height of the head scarp, increasing the risk to the residence. Subsequent to our original report, we determined that the house is on a conventional foundation (no deepened support/piles. Based on this, it is our opinion that the residence is at imminent risk of damage given the proximity and geometry of the slide. We recommend that the slope area be stabilized immediately. Recommendations for stabilization of the slide area are provided below. We also understand that because of the height and inclination of the slopes in the vicinity of the site, that a geologic hazard assessment is being required by the City of Federal Way Revised Code Chapter 19. SITE CONDITIONS The subject site is situated on a natural bench situated in the west margin of the Federal Way Upland area. According to the King County Assessor Website, the site is irregular in shape, measures 140 to 225 feet wide (northeast to southwest) by 295 to 475 feet deep (northwest to southeast), and encompasses approximately 1.61 acres. The site is bounded by a existing residential development on the south, Dumas Bay Centre on the north, Dash Point Road on the southeast, and the Puget Sound on the west. The ground surface at the site ranges from gently to steeply sloping, with the residence being constructed on a natural bench as a daylight basement type residence. Slopes in the upland area range from 5 to 20 percent. The west portion of the site steepens to between 40 and 120 percent. Total topographic relief across the site is on the order of 60 to 65 feet. A large fir tree, designated an Eagle Tree, is situated at the top of the bluff slope in the south portion of the wall area. We expect that this tree will need to be removed during wall installation. Based on the Federal Way Critical Area Code, the steeper portions of the site meet the technical criteria of landslide hazard and erosion hazard areas. The County View topography is included as Figure 2. The recent landslide initiated on the City property to the north, extending onto the subject site. The failure scarp occurred just below the top of the bluff slope, dropping a total of 8 to 12 feet at the time of our last site visit. The proposed retaining wall will be constructed above the failure area in an effort to retain the upland area a protect the existing residence and appurtenant structures. As indicated above, the head scarp is approximately 6 feet from the deck supports, and as close at 14 feet to the residence. Our review of the previous geotechnical work at the site for the construction of the residence indicates that the structure is founded on a conventional foundation, rather than deepened foundation elements as expected originally. It is therefore imperative that the retaining wall be constructed as soon as possible to mitigate the risk of damage to the structure during the coming wet weather conditions. Site Soils The USDA Natural Resource Conservation Service (NRCS) Web Soil Survey maps the southwest portion of the site area are as Alderwood and Kitsap soils (AkF). Soils in the majority of the site area are mapped as Indianola loamy sand (InC). The Alderwood and Kitsap soils are derived from glacial till and forms on slopes of 25 to 70 percent. These soils are listed as having a "moderate to severe" erosion hazard when exposed and are included in hydrologic soils group B. The Indianola soils are derived from sandy glacial outwash and form on slopes of 5 to 15 percent. These soils are listed as having a "moderate" erosion hazard when exposed and are included in hydrologic soils group A. A copy of the NRCS-SCS soils map is included as Figure 3. Site Geology The draft the Geologic Map of the Tacoma North 7.5-minute Quadrangle, Pierce County, Washington by Troost, K.G., Booth, D.B., and Borden, R.K. (in review) indicates that the site is Elliot — Dash Point Rd September 15, 2016 Page 3 underlain by Vashon recessional outwash (Qvrl,) over advance outwash (Qva). These glacial soils were deposited during the most recent Vashon Stade of the Fraser Glaciation, approximately 12,000 to 15,000 years ago. The recessional and advance outwash soils consist of a poorly sorted, lightly stratified mixture of sand and gravel that may contain localized deposits of clay and slit that were deposited by meltwater emanating from the advancing and retreating ice mass, respectively. The recessional outwash is considered normally consolidated. Because the advance outwash was subsequently overridden by the glacial ice mass, it is considered overconsolidated and exhibits high strength and low compressibility characteristics. Based on the results of previous exploraitons, and our recent boring at the site, the soil profile consists of a veneer of recessional outwash sand and gravel over glacial till, and advance outwash sand at depth. A copy of the geologic map for the site area is included as Figure 4. The shoreline area at the site is mapped as intermediate and unstable on the Coastal Zone Atlas map, included as Figure 5. In general, the deeper glacial till and advance outwash deposits are glacially consolidated and typically in a very dense condition where undisturbed. However, the surficial recessional outwash soils, as well as the weathered surficial soils, are considered normally consolidated and in a loose to medium dense condition. Where the underlying soils are in a dense to very dense condition, this can result in a seasonal perched groundwater condition. We observed localized areas of seepage in the mid -slope area during our site visit, and expect that this is related to that zone, recessional over till. Subsurface Conditions Based on our review of the previous subsurface explorations and report prepared by AESI (1986) for the original building permit at the site, and the results of our recent boring, the site soils were observed to be somewhat different than the previously reported stratigraphy, recessional outwash over glacial till and advance outwash. Our boring encountered recessional outwash to a depth of approximately 16.5 feet bgs, 5 feet of silty sand with gravel that we interpret to be glacial till, and several feet of advance outwash that is underlain by blue -gray silt, likely the Lawton formation, a glacial lacustrine or lake deposit. We also observed that the majority of the granular soils encountered were in a medium dense condition, with the deeper Lawton clay being in a very stiff to hard condition. The Lawton was encountered in our boring located in the southwest portion of the site, adjacent to the timber deck. The boring was terminated at 36.5 feet in the Lawton. A copy of the boring log and laboratory test results are included in Appendix "A". CONCLUSIONS AND RECOMMENDATIONS Based on our data review, site observations, previous and recent explorations and our experience in the area, it is our opinion that the slope failure at the site was the result of significant wet weather conditions during the last winter. Although the failure initiated on the property to the north, it extends onto the subject site. We expect that the failure was related to uncontrolled surface runoff and the resultant saturated ground conditions. The large fir tree situated near the top of the slope will need to be removed for installation of the wall. We expect that the stump can remain in place with the wall being constructed around it, although that will be determined during construction. Geologic Hazards per Federal Way Revised Code The City of Federal Way Critical Areas Ordinance for Geologically Hazardous Areas (Chapter 19.05.0707G, 19.160, and Chapter 15.10) state "geologically hazardous areas shall mean areas that , because of their susceptibility to erosion, landsliding, seismic or other geological events, are not suited to siting commercial, residential or industrial development Elliot — Dash Point Rd September 15, 2016 Page 4 consistent with public health or safety concerns." The Revised Code of Federal Way is copied in italics, while our comments to the code are immediately following the code. Erosion Hazard Areas per Federal Way Revised Code Chapter 19.05.070.G(1) The City of Federal Way code defines erosion hazard areas as those areas having a "severe" or "very severe" erosion hazard due to natural agents such as wind, rain, splash, frost action or stream flow." The USDA NRCS maps the soils on the upland area as Alderwood and Kitsap soils and Indianola soils which have a "Moderate to Severe" and "Moderate" erosion hazard. Based on the mapping, the site does not meet the technical definition of an Erosion Hazard area per the City code. Provided BMPs are in place prior to the start of earthwork activities at the site, the site poses a low risk to surrounding and adjacent properties from potential erosion hazards. Landslide Hazard Areas per Federal Way Revised Code Chapter 19.05.070.G(2) The Federal Way City Code defines landslide hazard areas as "those areas potentially subject to episodic downslope movement of a mass of soil or rock including but not limited to the following areas: 1. Any area with a combination of. a. Slopes greater than 15 percent; b. Permeable sediment overlying a relatively impermeable sediment or bedrock, c. Springs or groundwater seeps. 2. Any area which has shown movement during the Holocene epoch, from 10,000 years ago to the present, or which is underlain by mass wastage debris of that epoch. 3. Areas potentially unstable as a result of rapid stream incision, stream bank erosion, and undercutting by wave action. 4. Areas located in a canyon or on an active alluvial fan, presently or potentially subject to inundation by debris flows or catastrophic flooding. 5. Areas that have a "severe" limitation for building site development because of slope conditions, according to the USDA SGS. 6. Those areas mapped as Class U (Unstable), Uos (Unstable old slides), and Urs (unstable recent slides) by the Department of Ecology. 7. Slopes having a gradient steeper than 80 percent subject to rock fall during seismic shaking" The site has slopes steeper than 15 percent, but no adverse or intersecting contacts are mapped on the site. The weathered till/glacial till contact on upland areas typically does not constitute an adverse geologic contact. No seeps or springs noted on the site. No areas of mapped landslide debris or activity were noted on the published USGS geologic map. No areas of alluvial fans are mapped nor were any alluvial fans noted in the vicinity of the site at the time of our site visit. The site soils (AkF, InC) are listed as having a moderate to severe building limitations because of the slope. The site slopes are not steeper than 80 percent which are subject to rock fall during seismic shaking. The site is located on a shoreline and has shown movement within the last year but not due to wave action. The site is mapped by the DOE Coastal Atlas as "U" unstable along the northern shoreline.. Based on our field observations and experience with the soil types observed and mapped on the property, the site does have one of the above indicators. However, the site soils are generally stable relative to deep-seated failure in their present configuration. The recent failure is likely related to the natural process of weathered soils being saturated by the winter rains and surface water runoff. Further, the loss of lateral support from the north property likely Elliot — Dash Point Rd September 15, 2016 Page 5 contributed to the movement on your site. In our opinion, the site does not meet the definition of a landslide hazard area per the City of Federal Way. Seismic Hazards per Federal Way Revised Code Chapter 19.05.070.G(3) The City of Federal Way Municipal Code defines seismic hazard areas as "those areas subject to severe risk of earthquake damage as a result of seismically induced ground shaking, slope failure, settlement or soil liquefaction, or surface faulting. These conditions occur in areas underlain by cohesionless soils of low density usually in association with a shallow groundwater table." Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in pore water pressure. The increase in pore water pressure is induced by seismic vibrations. Liquefaction mainly affects geologically recent deposits of loose, fine-grained sands that are below the ground water table. Based on the density of the mapped soil types, it is our opinion that the risk for liquefaction to occur at this site during an earthquake is negligible. Provided the design criteria listed below are followed, the proposed structure will have no greater seismic risk damage than other appropriately design structures in the Puget Sound area. Lateral Earth Pressures For planning and design purposes, the following soils information may be utilized. This information is based on our site observations and experience in the site area, and the subsurface conditions encountered in our boring. The upper soils encountered (slope area) consist of silty sand with gravel and occasional cobbles and boulders. These soils are in a medium dense condition. The upper portion of these soils is weathered to a loose to medium dense condition, about 3 to 5 feet in depth, and in a loose to medium dense condition. Below these shallow soils, silty sand and sand with silt was encountered to a depth 24 feet bgs. Below this depth, the Lawton clay was encountered to the full depth explored. All of the site soils were observed to be in a damp to wet condition. Active lateral earth pressures for these soils may be assumed to be 40 pcf, provided they are not sloping and groundwater is not present. This pressure assumes the wall can move at least 0.001*H in order to develop active pressures. If structural geofoam backfill is used with a 1 H:1 V wedge from the bottom of the exposed face of the wall, an active lateral earth pressure of 5 pcf is appropriate, in our opinion. Passive resistance from the upper 4 feet of the soils on the slope should be ignored. Below this an allowable passive earth pressure of 275 pcf may be used. We recommend this pressure be applied over twice the pile width. A seismic surcharge of 8*H should be used to account for the live load during the 975 year return period design earthquake based on the Mononabe-Okabe analysis. Soldier Piling Based on our site observations, we understand that site access is limited and that a driven H-pile wall (with timber lagging) is preferred. A driven soldier pile wall consists of steel H-piles or beams driven into the underlying soils to the recommended depth. After the pilings are installed, treated timber lagging, consisting of treated timber or pre -cast concrete panels are placed between the H-piles and provide lateral support. Given existing site grades, exposed wall heights may reach 8 feet. Based on discussions with the piling contractor and structural engineer, cantilevered piles are feasible. We recommend that soldier piles have a maximum spacing of four feet center -to -center in the steeper areas and six feet in the flatter areas (flatter than 1 H:1 V), but this should be verified by the structural engineer. The actual spacing should be determined by the project Elliot — Dash Point Rd September 15, 2016 Page 6 structural engineer based on other design information such as the size of the piling. To account for arching effects, lateral loading on the timber lagging can be reduced by 50 percent. Voids behind the lagging should be filled with clean sand or drainage sand and gravel, or structural foam and pea gravel. Specific criteria for structural foam can be provided based on the site conditions at your request. The native soils may be suitable for reuse as backfill material for the upper one foot behind the wall. Passive resistance from soil should be ignored in the upper 3 to 5 feet where there is a slope up to 3H:1 V below the toe of the wall. This should be verified by a structural engineer. The required depth of embedment must satisfy both lateral and vertical loading requirements. We recommend that soldier piles penetrate at least double the exposed wall height below the adjacent ground surface. Based on the geology at this site, we recommend that the piles be driven a minimum depth of 25 feet from the level of the bluff top, the location of the boring. This will provide adequate embedment into the very stiff/hard Lawton Clay. These recommendations should be included in the bid documents. Where the piles have greater than 8 feet of stick up (not expected), "deadman" piles should be considered. "Deadmen" are H-piles driven behind the production piles to provide additional lateral support for the wall. The "deadman" piles should be installed beyond the zone of influence, typically 10 feet or more behind the wall piling. Each deadman pile is typically staggered and attached to two production piles. We understand that the structural engineer has determine that deadmen are not required unless the wall configuration is modified. We also recommend that lagging be installed between the soldier piles. The timber lagging is installed with the ends behind the beam flanges. Lagging should be installed to a minimum of 3 feet (measured vertically) below the existing grade, below the wall. Typically, a geo-composite drainage material, such as Miradrain, is continuously placed on the exposed soil between the piles and connected to the drain pipe or weep drains at the base of the wall. The contractor should also provide means, such as weep holes or % to 1/4-inch or a gap in lagging, to prevent the buildup of hydrostatic pressures behind shoring walls as necessary. In our opinion, the care taken in construction of the weep drains at the base of the walls is critical. A positive connection with the drainage mat must be provided, and concrete contamination and plugging must be avoided. A representative of GeoResources should be on site during the installation process to verify the pile tip reaches the minimum embedment into the lower, dense silty soils, and is consistent with conventional construction standards. Geofoam Backfill and Drainage In the event significant backfill is required, geofoam is recommended. Geofoam consists of expanded polystyrene with a unit weight ranging from 1 to 3 pounds per cubic foot. For this project type we typically recommend geofoam meeting the requirements of ASTM D 6817 Type EPS22, based on the deformation properties. In addition, if carpenter ants are likely to be present on site we recommend using geofoam that has been treated to prevent insect infestation. We recommend the geofoam blocks extend horizontally a distance equal to the slope height and vertically at least 5 feet below the finish grades. The geofoam blocks should be placed in a staggered pattern so that the joints between the blocks do not align with the underlying or overlying rows. Gaps between the geofoam blocks should be completely filled as the blocks are placed with a free draining, granular material, such as pea gravel. A minimum of 6-inches of drainage material should be placed on the slope behind the geofoam and below the lowest row of geofoam. The drainage material below the bottom row of geofoam blocks should be graded so that the blocks sit level and a perforated or slotted drain pipe could be placed at the bottom of the excavation if groundwater is encountered. If a drain is required it should be conveyed to the same point as the other drains at the site. Where the perforated/slotted pipe connects to a tightline, a structure or check -dam should be utilized. Elliot — Dash Point Rd September 15, 2016 Page 7 Geofoam is subject to deterioration if exposed to petroleum products, such as gasoline or diesel fuel. We recommend that landscape maintenance equipment using these fuels not be allowed near areas of geofoam. During construction special care must be taken to avoid spilling fuel on the geofoam. A geotextile separator per WSDOT specification 9-33.2 could be placed over the geofoam to reduce the risk from spills. A minimum of 2-feet of separation should be maintained over the geofoam to the final grades where the blocks are below the yard. Small trees and shrubs with shallow root systems should be used as vegetation and irrigation should not be installed on or near the slope. A landscape professional should be consulted to recommend plant and a planting pattern. Slope Stability Based on our field observations and experience with the soil types observed and mapped on the property, the site soils are generally stable relative to deep-seated failure in their present configuration. The recent failure is likely related to the natural process of weathered soils being saturated by the winter rains and surface water runoff. Further, the loss of lateral support from the north property likely contributed to the movement on your site. The proposed retaining wall should greatly improve slope stability on the subject site and allow for the remediation of the disturbed area. Proper planning, design and excavation techniques will reduce the risk of potential surficial erosion or movement in slope areas during site activities and future development. Construction Considerations We recommend that we be called at the start of the pile installation to verify installation to the appropriate depths and spacing. We do not need to witness all of the piling, but do want to verify that conditions are as expected and that the piling are being installed as recommended, and that the deadman system is appropriate and correctly constructed. If you have questions, please call US. As previously indicated, the soils in the site area typically contain larger soil material (gravel, cobbles and boulders) as well as organic debris (roots). These materials can result in difficult driving conditions and the contractor should be prepared to deal with these if encountered. U'M7 Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in this area at the time this report was prepared. Although subsurface explorations were completed for this evaluation, soil conditions can change significantly both horizontally and with time. A contingency for unanticipated conditions should be included in the budget and schedule. Sufficient monitoring, testing and consultation should be provided by our firm during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether earthwork and foundation installation activities comply with contract plans and specifications. The scope of our services does not include services related to environmental remediation and construction safety precautions. Our recommendations are not intended to direct the contractor's methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. If there are any changes in the loads, grades, locations, configurations or type of facilities to be constructed, the conclusions and Elliot— Dash Point Rd September 15, 2016 Page 8 recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. We hope this satisfies your current needs. Please contact us if you need additional information or have any questions. We look forward to working with you on this project. Respectfully submitted by, GeoResources, LLC as HER 2228 50040 ed it r� BRADLEY P BiGGERSTAF; loraA;. � J� {�C Brad P. Biggerstaff, LEG Principal Dana C. Biggerstaff, PE Sr. Engineer BPB:DCB\bpb DoclD: Elliot. DashPtDr. RG Attachments: Figure 1: Site Vicinity Map Figure 2a: Wall Location Aerial w/ Boring Location Figure 2b: Site Plan with Wall Locaiton Figure 3: NRCS Soil Conservation Map Figure 4: Geologic Map Figure 5: Coastal Zone Atlas Appendix A: Soil Classification Table, Boring Log and Lab Test Results it W 33.; int irk .t Is Approximate Site Location (Map created from King County Public GIS iMap) GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: 253-896-1011 Fax: 253-896-2633 A— D.A' Not to Scale Site Location Map Proposed Slope Repair 3500 Dash Point Road Federal Way, Washington Doc ID: Elliott. Dash PointRd. F f June 2016 Figure 1 Approximate Site Location (Map created from King County Public GIS iMap) GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: 253-896-1011 Fax: 253-896-2633 Site and Exploration Plan Proposed Slope Repair 3500 Dash Point Road Federal Way, Washington Not to Scale Doc ID: Elliott. Dash PointRd. F June 2016 I �1 GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: (253) 896-1011 Fax: (253) 896-2633 --L'/"z /Or ie v, ng Gou w+y 1�rs Ia 1�C5e Site Plan 3500 Dash Point Road Federal Way, Washington NOT TO SCALE DocID: Elliot. Dash PointRoad I September 2016 Figurez.� Approximate Site Location An excerpt from the draft the Geologic Map of the Tacoma North 7.5-minute Quadrangle, Pierce County, Washington by Troost, K.G., Booth, D.B., and Borden, R.K. (in review) Qvrlc Recessional lacustrine deposits coarse Qva Advance outwash deposits GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: 253-896-1011 Fax: 253-896-2633 Not to Scale USGS Geologic Map Proposed Slope Repair 3500 Dash Point Road Federal Way, Washington Doc ID: Elliott. DashPointRd. F June 2016 Figure 4 Approximate Site location (Map obtained from the DOE Coastal Atlas https://fortress.wa.gov/ecy/coastalatiasn AV.4-4- GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Phone: 253-896-1011 Fax: 253-896-2633 Slope stabili4 C M,a Stable Intermediate 11140 Modified Unstable Unstable (old slide) > Unstable (recent slide) DOE Coastal Atlas Proposed Slope Repair 3500 Dash Point Road Federal Way, Washington Doc ID: Elliott. Dash PointRd. F June 2016 Not to Scale Figure 5 t11 ��� '� �— ice\ i i�.! � !1. ,i SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP SYMBOL GROUP NAME GRAVEL CLEAN GW WELL -GRADED GRAVEL, FINE TO COARSE GRAVEL GRAVEL I COARSE J GP POORLY -GRADED GRAVEL GRAVEL GM SILTY GRAVEL GRAINED More than 50% SOILS Of Coarse Fraction Retained on WITH FINES No. 4 Sieve GC CLAYEY GRAVEL SAND CLEAN SAND SW WELL -GRADED SAND, FINE TO COARSE SAND More than 50% Retained on No. 200 Sieve SIP POORLY -GRADED SAND SAND SM SILTY SAND More than 50% Of Coarse Fraction Passes WITH FINES No. 4 Sieve SC CLAYEY SAND 4 SILT AND CLAY INORGANIC ML SILT CL CLAY FINE GRAINED ORGANIC OL ORGANIC SILT, ORGANIC CLAY SOILS Liquid Limit Less than 50 SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT More than 50% Passes CH CLAY OF HIGH PLASTICITY, FAT CLAY No. 200 Sieve Liquid Limit 50 or more ORGANIC OH ORGANIC CLAY, ORGANIC SILT HIGHLY ORGANIC SOILS PT ' PEAT NOTES: SOIL MOISTURE MODIFIERS: 1. Field classification is based on visual examination of soil Dry- Absence of moisture, dry to the touch in general accordance with ASTM D2488-90. Moist- Damp, but no visible water 2. Soil classification using laboratory tests is based on ASTM D2487-90. Wet- Visible free water or saturated, usually soil is obtained from below water table 3. Description of soil density or consistency are based on interpretation of blow count data, visual appearance of soils, and or test data. GeoResources, LLC SOIL CLASSIFICATION SYSTEM 5007 Pacific Hwy. E, Ste 16 Fife, Washington 98424-2648 Ph. 253-896-1011 Fx. 253-896-2633 FIGURE A-1 TOTAL DEPTH: 36.5 DRILLING METHOD: HSA LOGGED BY: STM _ TOP ELEVATION: DRILLING COMPANY: Boreteo HAMMER TYPE: Cathead LATITUDE: DRILL RIG: RCT HAMMER WEIGHT: 140 pounds LONGITUDE: NOTES: TEST RESULTS Plastic Limits Liquid Limit -C % Water Content • o> SOIL DESCRIPTION DRILLING NOTES a E n E E% Fines (<0.075mm) o o m 0 y o w Cf) to C7 Penetration - ♦ (blows per foot) 10 20 30 40 50 0 Topsoil/ rootzone Brown gravelly SA(loose t medium dense, moist)(recessional outwash) k 4 4 5 occasional cobbles and boulders per drillers 11 2 11 - ii a 7 Eti[i s 7 3 :Y:• >:::-}: iL'.:;F• is ;:;;. 10 poorly graded sand with sit LS.[. L4'.5::f! .[: 10 :; [:FW •:•::—S-F13i: '::i e:lil iil . i i-I+1 V, 15 6 4 15 _ 16 Grayish brown sandy IL wit some grave r.i;. € '• !r (stiff, moist) s. i= 20— 5T 9 `• 11: 1; ... 12 14 Tan fine sand with silt (medium dense, moist I 1:. Blue -gray SILT very stiff to ard, moist) 25 — (glaciolacustrine) 9 6lz 13 19 ..... >i 'Ly: �y Yr: 30 7 = 7 a S'•>i' ' 12 13 NOTES Proposed Retaining Wall 1. Refer to log key for definition of symbols, abbreviations and codes 3500 Dash Point Rd 2. USCS designation is based on visual manual classification Federal Way, WA and selected lab testing 3. Groundwater level, if indicated, is for the date shown and may vary LOG OF BORING B-1 4. N.E. = Not Encountered 5. ATD = At the Time of Drilling JOB: Ell lot. Dash Poi ntRd Sheet 7 of 2 GeoResources LLC FIG. TOTAL DEPTH: 36.5 DRILLING METHOD: HSA LOGGED BY: STM �01? ELEVATION: DRILLING COMPANY: Boretek HAMMER TYPE: Cathead. LATITUDE: DRILL RIG: RCT HAMMER WEIGHT: 140 pounds LONGITUDE: NOTES: TEST RESULTS Plastic Limit Liquid Limit DRILLING -a -a 0 ca Lu Penetration - A (blows per foot) EME |5a-1 Cc 1O5--1 | | NOTES 1.Refer tolog key for definition ofsymbols, abbreviations and codes u.USCGdesignation isbased onvisual manual classification and selected lab testing 8.Groundwater level, ifindicated, iofor the date shown and may vary 4.N.E.~Not Encountered a.ATD=Atthe Time ofDrilling � U c � w o L:� a> N = 3 �u m � 0 0 O U c c U O C N � 0 � m � U � X W m m E s cc .- N o m Ca v E- 7 0 m U) cc I — Particle Size Distribution Report C C CC 0 coN \ r m O O O O CO O N S Sk ik Xk xk 100 I 1 I I I I I I I I I I I I 10 90 1 I I I I I I I f l l l 20 80 I 1 I I I l i I I I I I I I 30 70 m w 40 n Z 60 m F 1 1 1 11 11 I i i l 111 50 z 50 I I I I I I I I O 60 0: 40 I I I I I I m I I I I I 70 30 I [ I I I I I I I f I I I 80 20 I I I I I I! I ! l l I I 10 90 I I 11! I1 I 1 1 1 1 1 1 0 I I 100 100 10 1 0.1 0.01 0.001 GRAIL SIZE - mm. % Gravel % Sand % Fines +3" Coarse Fine Coarse' Medium Fine Silt I Clay 0.0 0.0 2.0 7.1 39.9 40.4 10.6 TEST RESULTS Material Description Opening Percent Spec.' Pass? poorly graded sand with silt Size Finer (Percent) (X=Fail) .375 100.0 #4 98.0 Atterberg Limits (ASTM D 4318 #10 90.9 PL= LL= Pl= #20 # 40 79.0 51.0 51. Classification #0 USCS (D 2487)= AASHTO (M 145)= #100 14.6 Coefficients #200 10.6 D90= 1.8074 D86= 1.1420 D60= 0.5073 D50= 0.4171 D30= 0.2891 D15= 0.1572 D10= Cu= Cc= Remarks Sample ID:092006 NM-7.6% Date Received: Date Tested: 8/2/16 Tested By: JPK Checked By: Title: (no specification provided) Source of Sample: B-1 Depth: 10 Date Sampled: 7/21/16 Sam le Number• 3 GeoResources, LLC Client: Tom.Elliot Project: Proposed Retaining Wall Fife, WA LPro'ect_No:_E11iot.DashPointRd Figure Tested By: _ _ . _ . Checked By: Particle Size Distribution Report 10C 9C 8C 7C Cr W Z 6C LL Z 5C w Ir 4C W 3C 2C iC C IN 1111111111111110111111118 10 PO 30 40 50 60 70 80 90 100 Z % Gravel %annWJ .aicc - 1 ni n. % Sand % Fines Coarse Fine Coarse Medium Fine Silt Clay >+ % +3" 1— 0.0 0.0 0.0 0.0 0.2 0.7 99.1 rcn TEST RESULTS Material Description oOpening Percent Spec.* Pass? Size Finer (Percent) (X=Fail) #10 100.0 Q #20 100.0 Atterberg Limits (ASTM D 4318 #40 99.8 PL= 23 LL= 43 Pl= 20 #60 99.4 E 00 ##100 99.2 Classification 0 99.1 USCS (D 2487)= CL AASHTO (M 145)= A-7-6(22) Coefficients o D90= D85= D60= c c D50= D30= D15= D10= Cu Cc Q Remarks cU Sample ID:092007 m C NM-26.8 U N Date Received: Date Tested: 8/2/16 U m Tested By: JPK aa) Checked By: m E y Title: o (1) x "- a)t (no specificarion provided) "J c Source of Sample: B-1 Depth: 30 e Sam le Number: 7_ N a)GeoResources, LLC _ m Fife, WA Client: Tom Elliot Project: Proposed Retaining Wall Date Sampled: 7/21/16 Tested By: . Checked By: _ 5C X 4C w 0 z r U 3C F- J d 2C 1C LIQUID AND PLASTIC LIMITS TEST REPORT Dashed line indicates the approximate / / upper limit boundary for natural soils G zJ / 01 i ML or OL MH or OH J 181 44.4 >, 44 NCL 43.6 [] 43.2 ° w 42.8 +- z c W O0 42.4 W w E 42 O > 41.6 lU LU ou 4U AU vu I w LIQUID LIMIT IMMINEMIN NESSIONNEM SE 11M No MEN IMMINNEVENNIMEEKIES E IMINEM NE 1010100EKEE MISIME IN MOMME ME NE IN EN NMm o�MIMSEM w Co NUMBER OF BLOWS N MATERIAL DESCRIPTION LL PL N to i N X m ■ 43 23 m o Project No. E11iot.DashPoin(Ribnt: Tom Elliot m Project: Proposed Retaining Wall CZ c� Source of Sample: B-1 Depth: 30 ° °Sample Number: 7 � — a) GeoResources, LLC Fife, WA PI %<#40 %<#200 USCS 20 99.8 99.1 CL ��] Remarks: Tested By: JPK - Checked By: CITY OF FEDERAL WAY COMMUNITY DEVELOPMENT DEPARTMENT DEVELOPMENT REVIEW COMMITTEE TRANSMITTAL DATE: September 23, 2016 TO: Cole Elliott, Development Services Manager FROM: FOR DRC MTG. ON. FILE NUMBER(s): RELATED FILE NOS.: PROJECT NAME: PROJECT ADDRESS ZONING DISTRICT. - Becky Chapin, Associate Planner Please email any comments. 16-104364-00-SH SF to be submitted Elliot H-Pile Wall 3500 SW Dash Point Road RS 15.0 PROJECT DESCRIPTION. Shoreline exemption for stabilizing retaining wall. Request includes removal of one tree. LAND USE PERMITS: PROJECT CONTACT. Brad Biggerstaff GeoResources LLC 5007 Pacific Hwy E, Suite 16 Fife, WA 98424 MATERIALS SUBMITTED: °' • Shoreline Exemption Permit Application • Geotechnical Report and Geologic Hazard Assessment. (Prepared by GeoResources LLC, dated September 1, 2016 and revised September 15, 2016) • Eagle Nest/Tree Removal OHWM WALL LOCATION APPROXIMATE LOCATION OF EXISTING DECK AND HOUSE 200' SHORELINE MANAGEMENT AREA NOT TO SCALE Site Plan Slope Repair 3500 Dash* Point Road Federal Way, Washington September 2016 1 Figure 2b EXISTING BULKHEAD WALL LOCATION `114�' �r Av _ 4, -�1 4-inch ADS Perf-Pipe (Dispersion) (2x10� 1 Ward APPROXIMATE LOCATION OF EXISTING DECK AND HOUSE Roof Drain .4-1nch ADS Tightline ( — If / f� i GeoResources, LLC 5007 Pacific Highway East, Suite 16 Fife, Washington 98424 Ph:253-896-1011 Fax:253-896-2633 North v a a 0 +j 6. a� a m U C 0 C l9 a W 7 Rebar X-Anchor .a Min 4' Rebar 4-inch ADS Perf-Pipe (Dispersion) Rebar X-Anchor ti Scale 1" = 30' FIGURE 2c - Site Plan -Drainage Project : Elliott - Dash Pt. Location : Federal Way Client : Elliott Date : October 22, 2016 Job #:Elliot. Dash PtRd. Main Level TOM-DECK-DASHPOINT W Main Level 8/3-0,12016 Page: I