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15-103940ACCESS AGREEMENT This ACCESS AGREEMENT (this "Agreement"), dated for reference purposes 1 2015, is entered into by and between Corporation of the Catholic Archbishop of S at_tl_e ("Owner"), Carl and Denise Jonasson ("Property Owner") and Pearson Drilling Inc. ("Contractor"), 1, Background. The Property Owner's contractor requires access of land at the Archbishop Brunett Retreat Center, 4700 SW Dash Point Road #100, Federal Way, Washington, for building improvements by City of Federal Way Permit #'s 15-10,1943-0045F, '15-103944-00- SF and 15-103947-00 SF. This access is limited to moving equipment owned and operated by the contractor to and from property owned by the Property Owner. This Agreement describes the condition of access to the Property.' The rights Linder this Agreement are not assignable. The equipment consists of the following: Boom truck with flatbed, mini excavator, 120 excavator, drill rig, truck and lowboy trailer, 2 plakups, mechanics truck, fuel truck, 5 loads of steel H-pile, tie -backs and timber lagging hauled in by tractor and highboy trailer. 2. Access. Owner hereby grants Properly Owner and the Contractor, and their respective employees, access to the Property per Drawing G1.0 dated 9I12115 by Jonasson Consultants LLG to complete the Work. The Work will be conducted in a manner that is the least intrusive or disruptive as is rensnEiahly possible. Property to be restored to original condition and all temporary control measures removed, No staging, soils deposition or sediment retention to occur on Owner's property. 3. Responsibility for Required Work. Property Owner shall be solely responsible for the cost of the Work and for paying and defending any and all liens, claims, loss or liability arising out of Property Owner or Contractor's entry on to the Propeity under this Agreement or otherwise. Contractor waives any right to place a lien against the Property or seek payment front Owner. Contractor shall be licensed, bonded, and olairitain commercial liability insurance in an arnount not less than 31,000,000.00 and shall indemnify, hold harmless, acid defend Owner from any claim of personal injury or property damage arising from the Work. 4. Term of Agreement. Access under this Agreement shall be terminated on November :30.2015, or withdrawn by Owner in writing, whichever is sooner. 5. Soil information — Prior to e,cecation of this agreement, Property Owner to furnish to Owner any soil information provided by their consultant properly Owner: Owner, Corporation of the Catholic Archbishop of Carl and Denise Jonasson Seattle By: By. :1 Its: (;Ufitt aCtot':its- �L ACCESS AGREEMENT RECEIVED (00" 14 7 6-31 OCT 13 201 CITY OF FEDERX "DS ------------- ---- _ i l I � o --- - _.- ------ ------------------- — - - _ r F---------------- - I i - - - - - I- - - '-- 1-------- - - ---- - -- - - - --.+_ 4 ----- - ------------------- ------------ i` ------------------ •ram. -.._ -- - - -• -ate '-- - - -- - - - -_ — fir. - - - - - •� - _ •._ +. b--= :1L _'� - ==»- _=ter •_:=` _ - -- - - - - - -- - cover bate S - - - - -- - - as f - - - _ - - ------ - - --- din • n - - - - - - - - - - - - _•�.-: : :_ - - - - � :fib'. -_ - - - :x - _a - _- _ - V ifi - ---` - - - ------ -- - - _ tack ed - - - - - - - - - - - - - Iched - - - - - - --- = _ slopes d _ _ +. ^ - - - -- - - - - - - Sa a - - - - - - - - - - �- _ -- ion co - - --- --= � - - - - - - - -=� foot centers - - - - - - - }� - - - - - r--� `.. planted - -=Y_._-�- -�`= - - - - - --- - _seed 'seedlings - - - _ - -J — - r-=-=�.=-c =_- - - �� _ - - - - - `_� -' - - - - - - - - :�. , .�_ . area -- - - - - - - - x used ;--i - - - - : Previous) - etat _ - - mil- - - - Ichin h h dromu - -:sli t soils near- - -71 exposed so - e e - --mow==l -_ - - �-�`-•- _ - - - - i` Y__�-- Iched - - - - - - h dromu - - - -- - - n Ansa - - = - - -- - - an and =:;.;ate ...=_•---- � - - - - Rea - - - - --- - - - e wall. _ ` - - -- -_ - .J_ - - -- - -- - - - - I seeded _ -- _ - --- n control - - -- - - - - - - - - erosion - - -- - _ - •'ram== - - -- - -- - ified and - - - ----- - � - - - - - --- tack -- - -- - - - - - - - _ Rhhm ' - _ - - - -- - - - — - 'r'-ram-- --- —_ _ ^ n . - - r �_• - -- - - - _ _ __ _ = a=•fir __ _ _ __ _ _ _�� - ^-"'•'�':q,?:..-. __ ten— r-- _ _ _ _ _ -'ram—_ _ _ p• _ _ _ _ _ _ _ _ -. _ l _ o be landscaped to conditions ---------- equal to or better than their' pre -slide conditions All yards tq ` -'vim _ yy -_,.� J'�J�!� 7•I.� r ' / r 5 ` �t7 'G' I�'•4 �_: fi 7�. �".ffi/ / I I', .rne- i ✓'' ', / ,7 ', :Hrri .�4 r i �, �'a_': I Vy o - g a ° ° p Pj �•� �I 1 ar \a ��\ \ 148� • vti r .• •Jr•e,o M1 , 2J,7 a Qg 1 -�.5 •� y •"' — ,, � Y' ' --------- __Isa.v��_o • �, � ..w. ' ° •�.:: '••'==-••%�' �'f 11 :fir"'' . ,,. _-:: -- ` I -- -"-`' -'- --- r 1 2. 7 I,;� it �. /r' - a gQYard to be landscaped similar to its Reagan P 1; /: t' Jonasson' Ansari �I, �; �,.. - �, condition prior to the slide - - r�i - - - ° - - -- � ill.t •' / lt i LL 6�, ---- ; -- - -- Donovan _ 1 , ` ! •-----------' ' RESUBMIT I ! ! MAR 3 0 201d I ---so ft CITY OF FEDERAL �AY i I cos All Included Properties d Z 3 Nm:9 U Co N O Co rn Q 3 N _ 65 L Co C9 � Ci KO ci 04 o�ln r U N v N 'o m Q 1 boy C �a•=-_ _ „ -- UC� _ a, _O t •N a O� W01 C �+ C �� I, I-- t-r. d U a) O E �CC o o E� 0 ~ N �aQ EC-1.0 Ills 11111110 "wiz Os� r. ....lb SW 307th 5t Remove & dispose of µ bunched up ivy 'Fir and Cedar Seedlings •• , uu- on . • • ft , r '" ■ + , r _ -+ • �• tom*- _ - IN �!i" r • -• �y '.* �.P. Imo, _ i'� 7 y'!'S' {ll ' i � , T ■ . ' .64 ki IL .I► �. �+ +_� ti•. _' -lit A f. 1' f _ I 1..Sf,� - VR41- J ti= •y a T •.?'r F Ii} _ 4* rye I r1} � ' t r r =t r i •/(.. �. w■ -10 *1i ''di dON i _ a. •� f�-,�±�•y 1 - •'� � mar M � '`� •.1 .. ..+ i. • 416 t■ , ..Improve gravel J i pathway 406y drk-_ .LIP 434s►lv-307t h St { ' o r - +'' - of �l CITY OF Federal Way RECEIVED AUG 07 2015 CITY OF FEDERAL WAY CDS iCommi.q%iTY & ECO,Na iiC DE"*'EiAP 0A1T ` T 4"f 33325 &e* . venire Federal Way, WA 98003-6325 253-835-2607;Fax 253-835-2609 www.ci offederalway.com SHORELINE SUBSTANTIAL DEVELOPMENT PERMIT EXEMPTION APPLICATION i Mile # O BE COMPLETED BY APPLIcmNIT Project ]dame: _Dumas Bay West Homeowners Project Address. 4346 svv 307rk ct. Federal Way. WA 9"23 =',PPlicant: czar, dooesm Mailing Address: 434 SW 30; th St. Federal Wav, WA 990231 i 1 T 1' ^� n/ n /'1 1 '++ ^ rnorie 141mber: 2�rn-yn-1-1 i 1 n T :�s�r. ' FAO S�ii"'iiirir vi i 2477 uli$ii1?L�-r r,,-mair cari.jonassofl( )armcati�.rlei t J itz:'✓L Li__ti Uii L i Ji3L L'�SSL�iST SS J l 17�-')7-�Oilli• Vac :t^ude:ich senr ofNeets ti2e ..:�:.ta.n`'\AYh *Washington Administrative Code online; apps.leg.wa.gov 8/4/15 Apnlicnni's 4�!ign,?Ture baste I TO BE COMPLETED BY STAFF 1) The proposed development is consistent with Section ( -- 1) 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 ❑l Shoreline Variance ❑ Shoreline Conditional Use 14 Review, Approval or Permit by other State or Federal Agency l] S r ai.o �1 �i1!A B ul 1Ck i&i Wr m � t _ 'W Lr rha s ��rc�tg_ h-d-aIact4c'«�, a dvejLe � 3) Proposal complies with applicable provisions of the City's Shoreline Master Program. Yes ❑ No Condition(s) attached: X Yes ❑ No 02k-k1Lt DR5'�� +U tl KA IS�,b hi2 a. IndsAZLI t2 V— r- cis _ 4) In accordance with FWRC Section 15.05.130, this application is hereby: A, Approved ❑ Denied Director, Community Development Department Distribution: 9 Applicant 1. OwneiS, ctt rr, f�(>Srxr i , Tp�r%Li` File Outside Agency CCCONOIL e Bulletin #143 — March 25, 2013 2 of 2 k:\Handouts\Shoreline Exemption FILE Conditions of Shoreline Exemption Approval Federal Way Revised Code (FWRC) 15.05.130 `Shoreline Exemption' Dumas Bay West Homeowners, File #15-103940-00-SH The Planning Division has approved the attached 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 August 7, 2015, subsequent resubmittals received September 18, 2015, and the following conditions. PROPOSAL The Dumas Bay West Homeowners, LLC have proposed to construct a slope stabilization wall at the top of the slope at the north side of four residential properties, known as Jonasson, Reagan, Ansari, and Donovan properties. The properties are located at 4346, 4342, 4338 SW 307"' Street and 30625 43`d Avenue SW. The proposed retaining wall will provide a structural system at the crest of the coastal bluff that can be retrofitted in the future according to the volume of mass wasting that occurs below the wall in response to the continued coastal erosion process. DECISION ■ Shoreline Management The properties are designated `Urban Conservancy' in the city's Shoreline Management Plan (SMP) overlay. Areas within 200 feet of the 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. ■ 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 Study and Recommendations, prepared by PanGEO, for the proposed soldier pile and tieback retaining wall along the top of the slope of the four properties. The City's geotechnical consultant Amec Foster Wheeler (Amec) provided third party review of the reports, which included a few comments. PanGEO submitted revised reports on September 18, 2015. Based on the resubmitted reports Amec is satisfied that all comments have been adequately addressed and the geotechnical documents appear to conform to FWRC Chapter 15.10, Critical Areas. Amec concurs with the recommendations as proposed in the PanGEO geotechnical reports and erosion control plans. As proposed, the slope stabilization located along the Jonasson, Reagan, and Ansari properties consists of soldier piles embedded 50-60 feet into the ground. In the vicinity of the recent landslide area there will be up to 10 feet of new backfill being retained by the wall, around 10 feet of timber lagging will be exposed. There will be no exposed wall on the Jonasson and Ansari properties. The Donovan property will have a separate retaining wall, similar construction, with soldier pile embedment length of 50 feet and a small portion may retain up to 6 feet of new backfill. ■ Retaining Walls Based on FWRC 19.120.120, Rockeries and retaining walls, for single-family residential lots, retaining walls must be 1) a maximum of six feet in height as measured from finished grade at base of wall to top of wall; 2) composed of brick, rockery, textured or patterned concrete, or other masonry product. Other materials may be used with approval of the community development director. A modification to the height maximum, pursuant to FWRC 19.120.050, is approved as there is no feasible and reasonable alternative to the 10-foot wall height, the slope has already failed and the proposed retaining wall at the proposed height will minimize the impact of a future landslide, and the 10-foot retaining wall with backfill on the Reagan property will reduce the risk to health and safety as well as reduce the risk of property damage due to the recent landslide. The city has also approved the wood lagging used in the retaining wall structure as an alternative to the required masonry product. The exposed wall is only visible from the toe of the slope/beach and is not visible from neighboring properties. There is potential that additional timber lagging and tie backs will be required if additional landslide activities occur on any of the properties. ■ Beach Nourishment Over time it is understood that wave erosion and mass wasting may occur below the retaining wall providing sediment to the beach in the process. However, there is potential for the wal I to reduce the amount of natural sediment being added to the beach. At the time when additional lagging and/or tiebacks are required, evaluation of beach nourishment may be required. Analysis of the amount of sediment reaching the beach and the need of supplemental beach nourishment may be required at that time. CONDITIONS OF APPROVAL 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) the attached Inadvertent Archaeological and Historic Resources Discovery Plan must be implemented. 2. PanGEO 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 PanGEO, verifying construction of the wall is in compliance with recommendations of the geotechnical report must be submitted no later than 30 days after the walls have been finalled. 4. An as -built survey of the retaining wall is required after the wall is constructed. This will provide baseline data for monitoring any long-term movement of the wall. 5. At the time that additional timber lagging and/or additional tiebacks are required, based on the pre- determined height established on sheet SS40 of the submitted plans, please contact the Planning Department to inform them of the construction work that is to occur and to obtain permit approval. Prepared by: Becky Chapin, Associate Planner Date: October 13, 2015 15-103940 Doi i D 70976 Access to proper"es from The Palisades property, via their 7 stages path in red. RESUBMITTED The gravel path is approximately 6 feet wide, to be repaired when the walls are complete. The blue portion diverting from the 7 stages path running east over ivy and downed branches need not be repaired, as long as major live timber is not damaged or cut. A path has been flagged. City of Federal Way standard silt fence hk�bLpath Best Management Practices to be Employed Construction activity will be staged to minimize exposed areas. Stabilized construction entrance at Palisades entrance. Sweep and remove any sediments tracked onto pavement. Staging area will be used for sediment retention, if needed. Dust is to be controlled on the construction sites. All disturbed areas will be re -vegetated. Silt fences will be removed from site upon completion. an ■ d Curb ramp 0 Erosion Control, Grading, Access, G1 Dumas Bay West Homeowners ' Jonasson, Reagan, & Ansari properties Staging, offload & reload area, r. r, when dry, Path to properties from 7 stages path requires no clearing. Trees are avoided, except for occasional limbing up of branches for equipment clearance. Ivy ground cover will re-establish soon after Contract completion Access to Jonasson, Reagan & Ansari Properties Excess spoils deposition, 27' x 49' S E P 18 2015 CITY OF FEDERAL WAY CDS Max width available between houses = 8'. 4' chain link and tubular steel fence and some plants would have to be removed and replaced. Alternate paths ■ Staging sae see Above_ JONASSON CONSULTANTS LLC Designed _CJ 4346 SW 307th St, Federal Way, WA 98023 Date_9/17/15 206-963-1718 Revision 1 M 01 i ZV'JA 'ry�r�+:..�%r•F .. vllw .• r++ram "tip "' f. a'• i� Y �rf 4ft{° ,.. •'" ..,, _'. ►= 30625 43rd Ave Stilt/ '•} I e t� • � � R r r � f + �'4.frl�l�iEtli_r I�,r ' ��l'�.i�*µ •� f � - " f+ A � i r w r*,ment •� R • 4 ■ I ctics to be E +;tivity will be R staged tominimize exposed areas. I 1 fuction entrance off of 43rd Ave. ve any sediments trace ono pavement. OU It w i � - • '�'� +,ma's :.j71% �ti 1: ..� . :I pill Google-earth 4jvj9'3S-0' 14 I2L°23'1�-",;' .. c ev 96 F- eve c i WfC 0 Erosion Control, Gra C73 _ Dumas Bay West Homeown( RESUBMITTED Dumas Bay West Project No. 15-046 Summary of Comments and Responses SEP 18 2015 CITY OF FEDERAL WAY CDS 1. The global stability results discussed in the Geotechnical Engineering Study dated July 16, 2015, for Section B and presented in Figure 6 should be explained in more detail. The model represents undisturbed soils, and therefore represents the stability at some setback distance from the scarp, similar to Figure 4. However, the safety factor would be lower for a potential slip surface that started from the observed tension cracks and continued through the slide debris because the tension crack and the slide debris would not have any cohesive strength. Response: Additional discussion regarding this analysis and conclusions is included in sections 6.2 and 6.3 of the Geotechnical Engineering Study report. 2. The recent landslide on the Regan parcel has left a near vertical main scarp and other tension cracks in the backyard of the residence. For safety purposes, PanGEO could recommend a minimum distance that residents should stay back from the bluff edge in the interim, until the retaining wall is constructed. Response: Recommendations for interim precautions added to the Geotechnical Engineering Recommendations for the 4338 SW 307th Street parcel. 3. The lateral earth pressure diagrams provide recommendations for surcharges at the top of the retaining wall, but the text of the report states that there will not be any surcharges. An explanation for the surcharge recommendations should be provided, or the surcharge could be removed from the diagrams. Response: Clarification added to text that surcharge load need not apply. 4. The geotechnical engineering recommendations for 4342 SW 307th Street and 30625 43rd Avenue SW state that wall backfill will be placed. Recommendations for the type of backfill and placement methods should be provided by PanGEO. Response: Backfill recommendations included in Geotechnical Engineering Recommendations for these two parcels. 5. We recommend that PanGEO review and approve the contractor's submittal for the "construction sequence narrative and description including equipment list and key personnel," as stated on the Structural Notes SS 1.0, 00603, to verify that the contractor's approach does not adversely affect site stability during construction, Response: Recommendation to review submittal added to Construction Considerations. Dumas Bay West Project No. 15-046 6. We recommend PanGEO be on site during construction to monitor slope stability conditions and confirm construction activities do not adversely affect site stability. Response: Recommendation added for on -site construction support services by PanGEO representative(s). 7. An as -built survey of the retaining wall should be required since this will provide baseline data for monitoring any long-term movement of the wall. Response: Recommendation added for as -built baseline. 8. We understand the goal is to avoid disturbing the slope on the downhill side of the soldier pile retaining wall. However, it is likely some soils will fall on the slope during drilling of soldier pile holes, and localized slope disturbance will occur by foot traffic for guiding soldier piles, and installing lagging and tiebacks. Therefore, the project plans should include erosion control requirements for the solider pile wall construction area, for both during and after construction, similar to what is shown on plan sheets G1.0 and G2.0 for the access routes. Response: Erosion control plans (by others) will be modified accordingly. September 16, 2015 Project No. 15-117 Mr. & Mrs. Carl Jonasson 4346 SW 307' Street Federal Way, Washington 98023 Subject: Geotechnical Engineering Recommendations 4346 SW 307t' Street Federal Way, Washington Dear Mr. & Mrs. Jonasson, Fl-anGE@) C O R P O R A T t O otechnical a Earthquake Engineering Consultants RESUBMIT"ED SEP 18 2015 CITY OF FEDERAL WAY CDS PanGEO, Inc. (PanGEO) prepared this letter report presenting our geotechnical engineering design recommendations for a slope stabilization wall to be constructed at the crest of the bluff on the north side of the subject residential property. The purpose of this wall is to provide long-term protection from mass wasting and slope retrogression at the crest of the coastal bluff that is experiencing sloughs and landslides to the north and below the subject residence. This letter report is supplemental to the geotechnical engineering study report that was prepared by PanGEO titled Dumas Bay West Coastal Bluff Stability Evaluation, and dated July 16, 2015, to address the overall geotechnical condition of the coastal bluff that runs along the northern (rear) portion of all the Dumas Bay West Homeowners (DBWH) properties. Please refer to that report for a discussion of the geologic, groundwater and geotechnical conditions of the DBWH properties, including the subject parcel. A discussion is provided in the coastal bluff stability report (PanGEO, July 16, 2015) regarding the field explorations, laboratory testing program, geotechnical slope stability analyses and conclusions regarding the stability of the coastal bluff that flanks the northern side of the DBWH properties. Retaining Wall Purpose and Design Recommendations The concept of the retaining wall recommended herein is to provide a structural system at the crest of the coastal bluff that can be retrofitted in the future according to the volume of mass wasting (sloughing or landsliding) that occurs below the wall in response to continued coastal erosion processes. Upon the completion of the initial construction, there will be little or no exposed face of wall. Slope movements below the wall may then 3213 Eastlake Avenue E, Suite B Seattle. DNA 98102 (206)262-0370 FAX (206) 262-0374 Page 2 Project No. 15-117 September 16, 2015 be allowed to occur until a pre -determined height of the wall is exposed that requires retrofitting to increase the lateral resistance of the system. Up to this pre -determined height, lagging or facing elements will need to be installed to prevent caving of retained soil from between the vertical elements. The system may be comprised of conventional soldier piles that can function in pure cantilever up to a pre -determined limiting height according to the structural moment resistance of the system. If slope movements expose a portion of the soldier piles, conventional lagging should be provided. If slope movements continue to expose the wall such that the pre -determined limiting height is reached or exceeded, additional lateral restraint should be provided for the wall system in the form of permanent ground anchors (tiebacks). A second and possibly third pre -determined height of exposed wall should also be identified when additional row(s) of tiebacks are required. The pre- determined heights and retrofit action required should be identified on the structural drawings for the wall. The system may also be comprised of micropiles with vertical elements at the location where a wall face would be constructed in the future, but also tied -back with a battered micro -pile connected by a grade beam to add lateral resistance to the system and provide for a taller exposed height before addition of tiebacks for additional lateral resistance is required. Limiting heights and retrofit requirements should be shown on the structural drawings similar to the soldier pile option described above. Figure 1 (attached) provides lateral earth pressures that may be used for structural design of either of the systems described above with a single point of lateral restraint, or for pure cantilever of a soldier pile system. Figure 2 (also attached) provides lateral earth pressures that may be used for structural design of the retrofit options for multiple rows or lateral restraint elements (tiebacks). The minimum embedment length for the vertical elements (soldier piles) should be 60 feet. The surcharge load shown in both figures is generic and need not be applied if surcharge loading is not present. Global Stability No new backfill or loading above the slope will be required on the subject parcel. The vertical elements (soldier piles) are being installed as a precautionary measure in anticipation of possible future slope movements similar to the recent landsliding on the adjacent parcel to the east. Figure 3 presents the results of global stability analysis with the inclusion of the retaining structure as a soldier pile and the incremental increase in loading due to the new backfill. The stabilization provided by the soldier pile increases 15-117 DBW Parcel 1 Wall Design Recommendarions_final.docx PanGEO, Inc. Page 3 Project No. 15-117 September 16, 2015 the overall global stability to 1.24 from 1.12 as compared to the existing condition (Figure 3 from PanGEO, July 16, 2015). Tiebacks Tiebacks will not be required as part of the initial installation of wall elements on the subject parcel. The following recommendations are provided for future addition of tiebacks should slope movements expose sufficient height of wall to require increased lateral restraint for structural stability. The manner in which the tieback anchors carry load will depend on the type of anchor selected, the method of installation, and the soil conditions surrounding the anchor. Accordingly, we recommend use of a performance specification requiring the contractor to install anchors capable of satisfactorily achieving the design structural loads, with a pullout resistance factor of safety of 2.0. For planning purposes, however, the anchors may be sized for an allowable skin friction value of 2.5 kips per lineal foot of anchor bond length, assuming that small diameter (about 6 inches) pressure -grouted tiebacks will be used. Post -grouting may also be needed in order to achieve the design capacity. We recommend that the allowable tieback loads be limited to about 90 kips per anchor. The tiebacks for this project should be installed by experienced personnel. Temporary casing may be required to prevent excessive ground loss. In addition, the use of compressed air to flush the drill cuttings must be properly controlled; the use of excessive amount of compressed air while drilling tiebacks could lead to reduction of soil strength and ground movements. The actual capacity of the anchors should be checked with 200% verification tests. At least one 200% test should be performed prior to installing production anchors. All production anchors should be proof tested to 150% of the design load. The anchor installations should be conducted in accordance with the latest edition of the Post Tensioning Institute (PTI) "Recommendations for Prestressed Rock and Soil Anchors". Elements of the testing are as follows: Verification Tests 200% Tests r Prior to installing production anchors, perform a minimum of one test each on each anchor type, installation method and soil type with the tested anchors constructed to the same dimensions as proposed production anchors. Test locations to be determined in conjunction with, and approved by, the geotechnical engineer. 15-117 DBW Parcel 1 Wall Design Recommendarions_final.docx PanGEO, Inc. Page 4 Project No. 15-117 September 16, 2015 • Test anchors, which will be loaded to 200% of the design load, may require additional prestressing steel (steel load not to exceed 80% of the ultimate tensile strength) or reinforcing of the reaction soldier pile. • Load test anchors to 200% load in 25% design load increments, holding each incremental load for at least 5 minutes and recording deflection of the anchor head at various times within each hold to the nearest 0.01 inch. • At the 200% load, the holding period shall be at least 60 minutes. • A successful test shall provide a measured creep rate of 0.04 inches or less at the 200% load between 1 and 10 minutes, and 0.08 inches or less between 6 and 60 minutes, and all time increments shall have a creep rate that is linear or decreasing with time. The applied load must remain constant during all holding periods (i.e. no more than 5% variation from the specified load). Verification tested anchors not meeting the acceptance criteria will require a redesign by the contractor to achieve the acceptance criteria. Proof Tests 150% load tests on all production anchors • Load test all production anchors to 150% of the design load in 25% design load increments, holding each incremental load until a stable deflection is achieved (record deflection of the anchor head at various times within each hold to the nearest O.Olinch). • At the 150% load, the holding period shall be at least 10 minutes • A successful test shall provide a measured creep rate of 0.04 inches or less at the 150% load between 1 and 10 minutes with a creep rate that is linear or decreasing with time. The applied load must remain constant during the holding period (i.e., no more than 5% variation from the 150% load). Anchors failing this proof testing creep acceptance criteria may be held an additional 50 minutes for creep measurement. Acceptable performance would equate to a creep of 0.08 inches or less between 5 and 50 minutes with a linear or decreasing creep rate. In the tieback construction, a bond breaker shall be constructed in the no load zone when the installation procedures use single stage grouting. As discussed above, the structural design of the retaining wall should include pre- determined height(s) of exposed wall that would require installation of additional tiebacks if slope movements below the wall result in exposure of wall face. Installation of tiebacks in the future should be accomplished as soon as possible after observation that exposed wall heights have exceeded the pre -determined limits and should follow the installation and testing criteria recommended above. 15-117 DBW Parcel 1 Wall Design Recommendations_final.docx PanGEO, Inc. Page 5 1 Project No. 15-117 September 16, 2015 Baseline Survey and Monitoring Since installation of vertical elements (soldier piles) on the subject parcel will not result in grade changes or new wall backfill, ground movements are not expected. However, existing structures or improvements to be saved that are near the construction zone should have baseline physical location data established prior to beginning work. As a minimum, optical survey points (points known, or PK's) should be established at the corners and midpoint of the residential structure. The selection of monitoring points should be made with concurrence of the geotechnical engineer. The monitoring program should include measurement of changes in both the horizontal and vertical directions. The monitoring should be performed at least weekly while active wall construction is underway. The monitoring should be by a licensed surveyor, and the results be promptly submitted to the geotechnical engineer for review. The results of the monitoring will allow the design team to confirm design parameters, and for the contractor to make adjustments to means and methods of construction, if necessary. A post -construction baseline survey of the wall should also be made so that in the event that future slope movements below the wall occur there is a record of the original wall construction location for comparison purposes. Construction Considerations The following should be taken into consideration during the design and construction of the retaining structure described herein: 1. Based on the groundwater level measurements taken in the borings drilled for the DBWH (PanGEO, July 16, 2015), groundwater is not expected to be encountered during construction of vertical elements (soldier piles) or for tiebacks. 2. Care should be taken during construction to not unnecessarily place live load surcharges close to the crest of the bluff as this could result in local instability. 3. Upon completion, grades between the retaining structure and the residential structure should be returned to similar conditions as before construction such that surface water runoff is not directed over the wall and onto the steep slopes below the coastal bluff. 4. We recommend that the following should be incorporated into the project plans and specifications: • The geotechnical engineer shall verify the suitability of all soldier pile holes before concrete placement; 15-117 DBW Parcel 1 Wall Design Recommendations_fmal.docx PanGEO, Inc. Page 6 ^} Project No. 15-117 September 16, 2015 • Temporary casing should be used if caving occurs as determined by the geotechnical engineer; * Tremie methods shall be used for concrete placement in all holes having 3 or more inches of accumulated water; and • All soldier pile holes shall be drilled and filled with concrete on the same day. 5. PanGEO should review the contractor's submittal for the construction sequence narrative and description including equipment list and key personnel to verify that the contractor's approach does not adversely affect site conditions or slope stability during construction. 6. A representative from PanGEO should be on site during construction to monitor slope stability conditions and to confirm that wall construction is consistent with design parameters and assumptions. If you have any questions, or require additional information, please contact our offices at (206) 262-0370. Sincerely, Robert E. Kimmerling, P.E. Principal Engineer Attachments: Figure 1— Wall Design Parameters, Cantilever Wall / Single Tieback Figure 2 — Wall Design Parameters, Multiple Tiebacks Figure 3 — Static Global Stability Analysis, Section `C' - with Soldier Pile and Backfill 15-117 DBW Pamel 1 Wall Design Recommendations_final.docx PanGEG, Inc. } Surface Surcharge = q B. X Micro -pile or Soldier Pile Wall Existing Grade 0'' No -Load 60° ; _ Zone 2Bq f H 0.4(1 - xl") q Bottom of Exposed Wall Height film (psi) Surcharge 27 pcf H14 o PresS.ure (Level Backslope) 5' m,n Seismic Pressure 1!/ irtCrem,tint ` 1:1 (max.) Z 67 pcf A "ve Pre $ r Passive Pre ure Notes: 1. Embedment (Z) should be determined by summation of moments at the bottom of the soldier piles or at ground anchor location if present. Minimum pile embedment shall be 60 feet below Existing Grade (crest of bluff). 2. A factor of safety of 1.5 has been applied to the recommended passive earth pressure value. Increase allowable passive pressure by 113 for resistance to tranislent loads, including seismic earth pressure. 3. Seismic earth pressure is the incremental value; combine with static active earth pressure. 4. Active, seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three limes the diameter of the vertical elements. 6. Use uniform earth pressure of 156 psf and 200 psf for lagging design with veriicai elarnents spaced at less than or equal to 6 feat and between 6 and 8 feet, respectively. 7. Refer to report text for additional discussions. FtnGE& C b R M 0 R A T Q O N Dumas Bay Nest Jonasson Parcel 4346 SW 307th Street Federal Way, Washington WALL DESIGN PARAMETERS CANTILEVER WALL! SINGLE TIEBACK No_ 15-117 No 11 s' Surface Surcharge = q 213q 6H (psf) Seismic Pressure Increment f3- Grade No -Load 0.5X Zone 600 , 7=--- 84 H X/H) 0.4(1 - a Surcharge 4 Pressure 27H psf 5' m 27 pcf (Level Sackslope) 1 Active Prey Micro -pile or Soldier Pile Wall 1:1 Bottom of Exposed Mall 1:1 (max.) Z 67 pcf 1 + Passive Pressure Note !,'Embedment (Z) should be determined by summation of moments at the bo±torn of t1!e soldier piles or at ground anchor location if present. Minimum pile embedment shall be 60 fret below crest of bluff 2. A factor of safety of 1.5 is included in the recommended allowable passive earth pressure value. increase allowable passive pressure by 1/3 for resistance to tranisient loads, including seismic earth pressure. 3. Seismic earth pressure is the incremental value; combine with static active earth pressure. 4. Active, seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three times the diameter of the vertical elements. 6. Use uniform earth pressure of 150 psf and 200 psf for lagging design with vertical elements spaced at less than or cquu! to 6 feet and between 6 and 8 feet, respectively. 7. Refe to report text for additional discussion and recommendations. Dumas Say West WALL DESIGN PARAMETERS Pan� Jonasson Parcel 1 MULTIPLE TIEBACKS q o x . e .. T . 0 4346 SW 307th Street Federal Way, Washington Project No. 15-117 Figure No. 2 '• � C3 � JV P r■ � I 1 9 07 a 0 1 I 1 I I cl I Z'i N HL � II cCD 1 �m a � I i n � ! IS a a h> rt o 1 �D N O � � � � � I 7 i � � * I o I' 1 ID In W ; I I I { A n L'1 p� O a n �D O ID T C Z (D + `L N 3 N f0 S j �IVI � � I I September 16, 2015 Project No. 15-115 Drs. Shaista Quddusi and Dr. Irfan Ansari 4338 SW 307t" Street Federal Way, Washington 98023 Subject: Geotechnical Engineering Recommendations 4338 SW 307" Street Federal Way, Washington Dear Drs. Quddusi and Ansari, PanGE@) ■ e o n v o w w r e s Ge0 echnicaI a Earthquake Engineering Consultants RESUBMIi7ED SEP 18 2015 CITY OF FEDERAL WAY CDS PanGEO, Inc. (PanGEO) prepared this letter report presenting our geotechnical engineering design recommendations for a slope stabilization wall to be constructed at the crest of the bluff on the north side of the subject residential property. The purpose of this wall is to provide long-term protection from mass wasting and slope retrogression at the crest of the coastal bluff that is experiencing sloughs and landslides to the north and below the subject residence. This letter report is supplemental to the geotechnical engineering study report that was prepared by PanGEO titled Dumas Bay West Coastal Bluff Stability Evaluation, and dated July 16, 2015, to address the overall geotechnical condition of the coastal bluff that runs along the northern (rear) portion of all the Dumas Bay West Homeowners (DBWH) properties. Please refer to that report for a discussion of the geologic, groundwater and geotechnical conditions of the DBWH properties, including the subject parcel. A discussion is provided in the coastal bluff stability report (PanGEO, July 16, 2015) regarding the field explorations, laboratory testing program, geotechnical slope stability analyses and conclusions regarding the stability of the coastal bluff that flanks the northern side of the DBWH properties. Retaining Wall Purpose and Design Recommendations The concept of the retaining wall recommended herein is to provide a structural system at the crest of the coastal bluff that can be retrofitted in the future according to the volume of mass wasting (sloughing or landsliding) that occurs below the wall in response to continued coastal erosion processes. Upon the completion of the initial construction, there will be little or no exposed face of wall. Slope movements below the wall may then _._ sake Avenue F. Suite 13 Seattle. WA 98I0-) (2061 262-0 370 FAX i206) 262-037-1 Page 2 Project No. 15-115 September 16, 2015 be allowed to occur until a pre -determined height of the wall is exposed that requires retrofitting to increase the lateral resistance of the system. Up to this pre -determined height, lagging or facing elements will need to be installed to prevent caving of retained soil from between the vertical elements. The system may be comprised of conventional soldier piles that can function in pure cantilever up to a pre -determined limiting height according to the structural moment resistance of the system. If slope movements expose a portion of the soldier piles, conventional lagging should be provided. If slope movements continue to expose the wall such that the pre -determined limiting height is reached or exceeded, additional lateral restraint should be provided for the wall system in the form of permanent ground anchors (tiebacks). A second and possibly third pre -determined height of exposed wall should also be identified when additional row(s) of tiebacks are required. Tile pre- determined heights and retrofit action required should be identified on the structural drawings for the wall. The system may also be comprised of micropiles with vertical elements at the location where a wall face would be constructed in the future, but also tied -back with a battered micro -pile connected by a grade beam to add lateral resistance to the system and provide for a taller exposed height before addition of tiebacks for additional lateral resistance is required. Limiting heights and retrofit requirements should be shown on the structural drawings similar to the soldier pile option described above. Figure 1 (attached) provides lateral earth pressures that may be used for structural design of either of the systems described above with a single point of lateral restraint, or for pure cantilever of a soldier pile system. Figure 2 (also attached) provides lateral earth pressures that may be used for structural design of the retrofit options for multiple rows or lateral restraint elements (tiebacks). The minimum embedment length for the vertical elements (soldier piles) should be 50 feet. The surcharge load shown in both figures is generic and need not be applied if surcharge loading is not present. Global Stability No new backfill or loading above the slope will be required on the subject parcel. The vertical elements (soldier piles) are being installed as a precautionary measure in anticipation of possible future slope movements similar to the recent landsliding on the adjacent parcel to the west. As no new fill or loading is proposed, the global stability will be improved over the existing condition by inclusion of the vertical elements (soldier piles). 15-115 DBW Parcel 3 Wall Design Recommendations_final.docx PanGEO, Inc. Page 3 Project No. 15-115 September 16, 2015 Tiebacks Tiebacks will not be required as part of the initial installation of wall elements on the subject parcel. The following recommendations are provided for future addition of tiebacks should slope movements expose sufficient height of wall to require increased lateral restraint for structural stability. The manner in which the tieback anchors carry load will depend on the type of anchor selected, the method of installation, and the soil conditions surrounding the anchor. Accordingly, we recommend use of a performance specification requiring the contractor to install anchors capable of satisfactorily achieving the design structural loads, with a pullout resistance factor of safety of 2.0. For planning purposes, however, the anchors may be sized for an allowable skin friction value of 2.5 kips per lineal foot of anchor bond length, assuming that small diameter (about 6 inches) pressure -grouted tiebacks will be used. Post -grouting may also be needed in order to achieve the design capacity. We recommend that the allowable tieback loads be limited to about 90 kips per anchor. The tiebacks for this project should be installed by experienced personnel. Temporary casing may be required to prevent excessive ground loss. In addition, the use of compressed air to flush the drill cuttings must be properly controlled; the use of excessive amount of compressed air while drilling tiebacks could lead to reduction of soil strength and ground movements. The actual capacity of the anchors should be checked with 200% verification tests. At least one 200% test should be performed prior to installing production anchors. All production anchors should be proof tested to 150% of the design load. The anchor installations should be conducted in accordance with the latest edition of the Post Tensioning Institute (PTI) "Recommendations for Prestressed Rock and Soil Anchors". Elements of the testing are as follows: Verification Tests 200% Tests Prior to installing production anchors, perform a minimum of one test each on each anchor type, installation method and soil type with the tested anchors constructed to the same dimensions as proposed production anchors. • Test locations to be determined in conjunction with, and approved by, the geotechnical engineer. Test anchors, which will be loaded to 200% of the design load, may require additional prestressing steel (steel load not to exceed 80% of the ultimate tensile strength) or reinforcing of the reaction soldier pile. 15-115 DBW Parcel 3 Wall Design Recommendations_final.docx PanGEO, Inc. Page 4 ^ Project No. 15-115 September 16, 2015 • Load test anchors to 200% load in 25% design load increments, holding each incremental load for at least 5 minutes and recording deflection of the anchor head at various times within each hold to the nearest O.Olinch. • At the 200% load, the holding period shall be at least 60 minutes. • A successful test shall provide a measured creep rate of 0.04 inches or less at the 200% load between 1 and 10 minutes, and 0.08 inches or less between 6 and 60 minutes, and all time increments shall have a creep rate that is linear or decreasing with time. The applied load must remain constant during all holding periods (i.e. no more than 5% variation from the specified load). Verification tested anchors not meeting the acceptance criteria will require a redesign by the contractor to achieve the acceptance criteria. Proof Tests 050% load tests on all production anchors • Load test all production anchors to 150% of the design load in 25% design load increments, holding each incremental load until a stable deflection is achieved (record deflection of the anchor head at various times within each hold to the nearest 0.01 inch). • At the 150% load, the holding period shall be at least 10 minutes • A successful test shall provide a measured creep rate of 0.04 inches or less at the 150% load between 1 and 10 minutes with a creep rate that is linear or decreasing with time. The applied load must remain constant during the holding period (i.e., no more than 5% variation from the 150% load). Anchors failing this proof testing creep acceptance criteria may be held an additional 50 minutes for creep measurement. Acceptable performance would equate to a creep of 0.08 inches or less between 5 and 50 minutes with a linear or decreasing creep rate. In the tieback construction, a bond breaker shall be constructed in the no load zone when the installation procedures use single stage grouting. As discussed above, the structural design of the retaining wall should include pre- determined height(s) of exposed wall that would require installation of additional tiebacks if slope movements below the wall result in exposure of wall face. Installation of tiebacks in the future should be accomplished as soon as possible after observation that exposed wall heights have exceeded the pre -determined limits and should follow the installation and testing criteria recommended above. 15-115 DBW Parcel 3 Wall Design Recommendations_fmal.docx PanGEO, Inc. Page 5 Project No. 15-115 September 16, 2015 Baseline Survey and Monitoring Since installation of vertical elements (soldier piles) on the subject parcel will not result in grade changes or new wall backfill, ground movements are not expected. However, existing structures or improvements to be saved that are near the construction zone should have baseline physical location data established prior to beginning work. As a minimum, optical survey points (points known, or PK's) should be established at the corners and midpoint of the residential structure. The selection of monitoring points should be made with concurrence of the geotechnical engineer. The monitoring program should include measurement of changes in both the horizontal and vertical directions. The monitoring should be performed at least weekly while active wall construction is underway. The monitoring should be by a licensed surveyor, and the results be promptly submitted to the geotechnical engineer for review. The results of the monitoring will allow the design team to confirm design parameters, and for the contractor to make adjustments to means and methods of construction, if necessary. A post -construction baseline survey of the wall should also be made so that in the event that future slope movements below the wall occur there is a record of the original wall construction location for comparison purposes. Construction Considerations The following should be taken into consideration during the design and construction of the retaining structure described herein: l . Based on the groundwater level measurements taken in the borings drilled for the DBWH (PanGEO, July 16, 2015), groundwater is not expected to be encountered during construction of vertical elements (soldier piles) or for tiebacks. 2. Care should be taken during construction to not unnecessarily place live load surcharges close to the crest of the bluff as this could result in local instability. 3. Upon completion, grades between the retaining structure and the residential structure should be returned to similar conditions as before construction such that surface water runoff is not directed over the wall and onto the steep slopes below the coastal bluff. 4. We recommend that the following should be incorporated into the project plans and specifications: ■ The geotechnical engineer shall verify the suitability of all soldier pile holes before concrete placement; 15-115 DBW Parcel 3 Wall Design Recommendation_final.docx PanGEO, Inc. Page 6 Project No. 15-115 September 16, 2015 • Temporary casing should be used if caving occurs as determined by the geotechnicai engineer; • Tremie methods shall be used for concrete placement in all holes having 3 or more inches of accumulated water; and • All soldier pile holes shall be drilled and filled with concrete on the same day. 5. PanGEO should review the contractor's submittal for the construction sequence narrative and description including equipment list and key personnel to verify that the contractor's approach does not adversely affect site conditions or slope stability during construction. 6. A representative from PanGEO should be on site during construction to monitor slope stability conditions and to confirm that wall construction is consistent with design parameters and assumptions. If you have any questions, or require additional information, please contact our offices at (206) 262-0370. Sincerely, Robert E. Kimmerling, P.E. Principal Engineer Attachments: Figure 1 — Wall Design Parameters, Cantilever Wall / Single Tieback Figure 2 — Wall Design Parameters, Multiple Tiebacks 15-115 DBW Parcel 3 Wall Design Recommendadons_final.docx PanGEO, Inc. Surface Surcharge = q 2Bq 6H (psf) Seismic Pressure Increment 0.5: B_ x Fx€st€nc Grade No -Load Zone 0.4(1 - x/") q Surcharge 27 pcf Pressure (I-evel8acks€ope) 1 Active Pressure h4icro-p'k or Soldier Pile Wall :xposed Wal( Height Passive Pressure H Natec: 1. Embcdment (Z) snould oe determined by summation of moments at the bottom of the soldier piles or 81 ground anchor location if present- Minimum pile embedment shall be 50 feet below Existing Grade (r.�st of bluff) 2. A factor of safety of 1.5 has beer) a};pued to the sac.nmmended passive earth pressure val+sr- Increase allowable passive pressure by 113 for resistance to Imnisierrt loads, including seismic earth pressure- 3. Seismic earth pressure is the incremental value; combine w€th static active earth pressure. 4. Active; seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three times the diameter of die vertical eitiment7. G. Use un torm earth pressure of 150 psf and 200 psf for lagging design with verGc;al elailitnls spaced at less than or equal to 6 feet and between 6 and E t8et, respectively. 7. Refer to report text for additional discussions. Emillr-11CISN I N C O R 0 O R A T[ D :h Dumas Bay West Ansaris Parcel 4338 SW 307th Street Federal Way, Washington WALL DESIC14 PARAMETERS ' CANTILEVER WALL f SINGLE TIEBACK �. No 15-115- — N,1 1 -- - -` A Surface Surcharge = q Seismic Pressure Incremen S X Micro -pile or Soldier Pile Wall � I1lIf! 0.GX GO° 213 Existina Grade No -Load Zone 0.4(1 - x/") q Surcharge Pressure 27H as 27 pcf (Level Racksiope) 1' v Active P e re- H :xposed Wall Height 1:1 (max.) Z ,cf t'a a 'ure Note: 1. Embedment (Z) should be determined by summation of momentsat the bottom of the soldier piles or nt around anchor location if present. Minimum pile embedment shall be 50 feet below crest of bluff. 2. A factor of safety of 1.5 is included in the recommended allowable passive earth pressure value. Increase allowable passive pressure by 113 for resistance to tranisient loads, including seismic earth pressure. 3. Seismic earth pressure is the incremental value; combine with static active earth pressure. 4. Active, seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wail face. 5. Passive pressure should be applied to three times the diameter of the vertical elements. S. Use uniform earth pressure of 150 psf and 200 psf for lagging design with vertical elements spaced at less than or equal to 6 feet and between 6 and 8 feet, respectively. 7. Refer to report text for additional discussion and recommendations. Dumas Bay West WALL DESIGN PARAMETERS Ansarls Parcel I� ULTIPLE TIEBACKS FbnGFO) ■< o o R. T E o 4338 SW 307th Street Federal Way, Washington Project No 15-115 Figure No 2 j F-bnGEO c 0 N P O R A 7 E 9 Geotechnical & Earthquake Engineering Consultants September 16, 2015 Project No. 15-098 RESUBMITTED Mr. & Mrs. Kirk Reagan 4342 SW 307th Street SEP 1 2015 Federal Way, Washington 98023 CITY OF FEDERAL. WAY CDs Subject: Geotechnical Engineering Recommendations 4342 SW 307th Street Federal Way, Washington Dear Mr. & Mrs. Reagan, PanGEO, Inc. (PanGEO) prepared this letter report presenting our geotechnical engineering design recommendations for a slope stabilization wall to be constructed at the crest of the bluff on the north side of the subject residential property. The purpose of this wall is to provide long-term protection from mass wasting and slope retrogression at the crest of the coastal bluff that is experiencing sloughs and landslides to the north and below the subject residence. This letter report is supplemental to the geotechnical engineering study report that was prepared by PanGEO titled Dumas Bay West Coastal Bluff Stability Evaluation, and dated July 16, 2015, to address the overall geotechnical condition of the coastal bluff that runs along the northern (rear) portion of all the Dumas Bay West Homeowners (DBWH) properties. Please refer to that report for a discussion of the geologic, groundwater and geotechnical conditions of the DBWH properties, including the subject parcel. A discussion is provided in the coastal bluff stability report (PanGEO, July 16, 2015) regarding the field explorations, laboratory testing program, geotechnical slope stability analyses and conclusions regarding the stability of the coastal bluff that flanks the northern side of the DBWH properties. Interim Precautions The recent mass wasting that occurred on the north side of the subject parcel has left an over -steepened condition at the top (head scarp) of the slide area and several tension cracks exist behind the main scarp. Until such time as remedial measure can be constructed, persons should avoid standing or walking in the areas north of the tension cracks and no machinery or other live load surcharges should be placed in the same area. 3213 Eastlake Avenue E, Suite B ScattIc. NV 9 810 2 (206)262-0370 FAX (206) 262-0374 Page 2 Project No. 15-098 September 16, 2015 Retaining Wall Purpose and Design Recommendations The concept of the retaining wall recommended herein is to provide a structural system at the crest of the coastal bluff that can be retrofitted in the future according to the volume of mass wasting (sloughing or landsliding) that occurs below the wall in response to continued coastal erosion processes. Upon the completion of the initial construction, there will be segments of the wall with little or no exposed face of wall, while in the area of recent landsliding, some new wall and backfill will be built to maintain a straight wall alignment and improve the stability of the crest of the bluff in this area. Slope movements below the wall may then be allowed to occur until a pre -determined height of the wall is exposed that requires retrofitting to increase the lateral resistance of the system. Up to this pre -determined height, lagging or facing elements will need to be installed to prevent caving of retained soil from between the vertical elements. The system may be comprised of conventional soldier piles that can function in pure cantilever up to a pre -determined limiting height according to the structural moment resistance of the system. If slope movements expose a portion of the soldier piles, conventional lagging should be provided. If slope movements continue to expose the wall such that the pre -determined limiting height is reached or exceeded, additional lateral restraint should be provided for the wall system in the form of permanent ground anchors (tiebacks). A second and possibly third pre -determined height of exposed wall should also be identified when additional row(s) of tiebacks are required. The pre- determined heights and retrofit action required should be identified on the structural drawings for the wall. The system may also be comprised of micropiles with vertical elements at the location where a wall face would be constructed in the future, but also tied -back with a battered micro -pile connected by a grade beam to add lateral resistance to the system and provide for a taller exposed height before addition of tiebacks for additional lateral resistance is required. Limiting heights and retrofit requirements should be shown on the structural drawings similar to the soldier pile option described above. Figure 1 (attached) provides lateral earth pressures that may be used for structural design of either of the systems described above with a single point of lateral restraint, or for pure cantilever of a soldier pile system. Figure 2 (also attached) provides lateral earth pressures that may be used for structural design of the retrofit options for multiple rows or lateral restraint elements (tiebacks). The minimum embedment length for the vertical elements (soldier piles) should be 60 feet. The surcharge load shown in both figures is generic and need not be applied if surcharge loading is not present. 15-098 DBW Parcel 2 Wall Design Recommendarions_final.docx PanGEO, Inc. Page 3 Project No. 15-098 September 16, 2015 Global Stability About one-third of the retaining structure will retain up to 10 feet of new backfill in the vicinity of the head scarp of the recent landslide area. Figure 3 presents the results of global stability analysis with the inclusion of the retaining structure as a soldier pile and the incremental increase in loading due to the new backfill. The stabilization provided by the soldier pile increases the overall global stability to 1.56 from 1.50 as compared to the existing post -slide condition (Figure 6 from PanGEO, July 16, 2015). Tiebacks The manner in which the tieback anchors carry load will depend on the type of anchor selected, the method of installation, and the soil conditions surrounding the anchor. Accordingly, we recommend use of a performance specification requiring the contractor to install anchors capable of satisfactorily achieving the design structural loads, with a pullout resistance factor of safety of 2.0. For planning purposes, however, the anchors may be sized for an allowable skin friction value of 2.5 kips per lineal foot of anchor bond length, assuming that small diameter (about 6 inches) pressure -grouted tiebacks will be used. Post -grouting may also be needed in order to achieve the design capacity. We recommend that the allowable tieback loads be limited to about 90 kips per anchor. The tiebacks for this project should be installed by experienced personnel. Temporary casing may be required to prevent excessive ground loss. In addition, the use of compressed air to flush the drill cuttings must be properly controlled; the use of excessive amount of compressed air while drilling tiebacks could lead to reduction of soil strength and ground movements. The actual capacity of the anchors should be checked with 200% verification tests. At least one 200% test should be performed prior to installing production anchors. All production anchors should be proof tested to 150% of the design load. The anchor installations should be conducted in accordance with the latest edition of the Post Tensioning Institute (PTI) "Recommendations for Prestressed Rock and Soil Anchors". Elements of the testing are as follows: Verification Tests 200% Tests • Prior to installing production anchors, perform a minimum of one test each on each anchor type, installation method and soil type with the tested anchors constructed to the same dimensions as proposed production anchors. • Test locations to be determined in conjunction with, and approved by, the geotechnical engineer. 15-098 DBW Parcel 2 Wall Design Recommendations_final.docx PanGEO, Inc. Page 4 Project No. 15-098 September 16, 2015 • Test anchors, which will be loaded to 200% of the design load, may require additional prestressing steel (steel load not to exceed 80% of the ultimate tensile strength) or reinforcing of the reaction soldier pile. • Load test anchors to 200% load in 25% design load increments, holding each incremental load for at least 5 minutes and recording deflection of the anchor head at various times within each hold to the nearest 0.01 inch. • At the 200% load, the holding period shall be at least 60 minutes. • A successful test shall provide a measured creep rate of 0.04 inches or less at the 200% load between 1 and 10 minutes, and 0.08 inches or less between 6 and 60 minutes, and all time increments shall have a creep rate that is linear or decreasing with time. The applied load must remain constant during all holding periods (i.e. no more than 5% variation from the specified load). Verification tested anchors not meeting the acceptance criteria will require a redesign by the contractor to achieve the acceptance criteria. Proof Tests Q50% load tests on all Droduction anchors • Load test all production anchors to 150% of the design load in 25% design load increments, holding each incremental load until a stable deflection is achieved (record deflection of the anchor head at various times within each hold to the nearest O.Olinch). At the 150% load, the holding period shall be at least 10 minutes • A successful test shall provide a measured creep rate of 0.04 inches or less at the 150% load between 1 and 10 minutes with a creep rate that is linear or decreasing with time. The applied load must remain constant during the holding period (i.e., no more than 5% variation from the 150% load). Anchors failing this proof testing creep acceptance criteria may be held an additional 50 minutes for creep measurement. Acceptable performance would equate to a creep of 0.08 inches or less between 5 and 50 minutes with a linear or decreasing creep rate. In the tieback construction, a bond breaker shall be constructed in the no load zone when the installation procedures use single stage grouting. As discussed above, the structural design of the retaining wall should include pre- determined height(s) of exposed wall that would require installation of additional tiebacks if slope movements below the wall result in exposure of wall face. Installation of tiebacks in the future should be accomplished as soon as possible after observation that exposed wall heights have exceeded the pre -determined limits and should follow the installation and testing criteria recommended above. 15-098 DBW Parcel 2 Wall Design Recommendations_final.docx PanGEO, Inc. Page 5 Project No. 15-098 September 16, 2015 Wall Backfill and Compaction Wall backfill is considered non-structural as no structure loads are anticipated above the wail backfill zone and the area will be re -landscaped following wall construction. Wall backfill may therefore consist of site -excavated material provided it can be placed and compacted to a firm and non -yielding or non -pumping condition, as determined in the field by a representative of PanGEO. The on -site soils may have fines contents high enough for the soils to be moisture sensitive. As such, any soil that is planned for reuse as wall backfill should be stockpiled and protected with plastic sheeting to prevent softening from rainfall. Baseline Survey and Monitoring Ground movements are expected to be relatively small as a result of wall construction activities since most of the construction will not result in an initial exposed wall face. However, existing structures or improvements to be saved that are near the construction zone should have baseline physical location data established prior to beginning work. As a minimum, optical survey points (points known, or PK's) should be established at the corners and midpoint of the residential structure and at 10-foot offsets to the north of the PK's on the residence itself. The selection of monitoring points should be made with concurrence of the geotechnical engineer. The monitoring program should include measurement of changes in both the horizontal and vertical directions. The monitoring should be performed at least twice weekly while active wall construction is underway, and should be increased to daily monitoring if movement is detected at the locations offset from the residence. The monitoring should be by a licensed surveyor, and the results be promptly submitted to the geotechnical engineer for review. The results of the monitoring will allow the design team to confirm design parameters, and for the contractor to make adjustments to means and methods of construction, if necessary. A post -construction baseline survey of the wall should also be made so that in the event that future slope movements below the wall occur there is a record of the original wall construction location for comparison purposes. 15-098 DBW Parcel 2 Wall Design Recommendations_final.docx PanGEO, Inc. Page 6 } Project No. 15-098 September 16, 2015 Construction Considerations The following should be taken into consideration during the design and construction of the retaining structure described herein: 1. Based on the groundwater level measurements taken in the borings drilled for the DBWH (PanGEO, July 16, 2015), groundwater is not expected to be encountered during construction of vertical elements (soldier piles) or for tiebacks. 2. Care should be taken during construction to not unnecessarily place live load surcharges close to the crest of the bluff as this could result in local instability. 3. Upon completion, grades between the retaining structure and the residential structure should be returned to similar conditions as before construction such that surface water runoff is not directed over the wall and onto the steep slopes below the coastal bluff. 4. We recommend that the following should be incorporated into the project plans and specifications: • The geotechnical engineer shall verify the suitability of all soldier pile and tieback holes before concrete or grout placement; • Temporary casing should be used if caving occurs as determined by the geotechnical engineer; ■ Tremie methods shall be used for concrete or grout placement in all holes having 3 or more inches of accumulated water; and. • All soldier pile holes shall be drilled and filled with concrete on the same day. ■ The geotechnical engineer shall witness and validate verification and proof testing of tiebacks and confirm that test results meet acceptance criteria. 5. PanGEO should review the eontraetor's submittal for the construction sequence narrative and description including equipment list and key personnel to verify that the contractor's approach does not adversely affect site conditions or slope stability during construction. 6. A representative from PanGEO should be on site during construction to monitor slope stability conditions and to confirm that wall construction is consistent with design parameters and assumptions. 15-098 DBW Parcel 2 Wall Design Recommendations_final.docx PanGEO, Inc. Page 7 Project No. 15-098 September 16, 2015 If you have any questions, or require additional information, please contact our offices at (206) 262-0370. Sincerely, 2 47 4 `i' Robert E. Kimmerling, P.E. Principal Engineer Attachments: Figure 1— Wall Design Parameters, Cantilever Wall / Single Tieback Figure 2 — Wall Design Parameters, Multiple Tiebacks Figure 3 — Static Global Stability Analysis, Section `C' - with Soldier Pile and Backfill 15-098 DBW Parcel 2 Wall Design Recommendations_fitWx1ocx PanGEO, Inc. Y LU a E m s LU Surface Surcharge = 4 X Micro -pile or Soldier Pile Wall I 1=xistina Grade 2Bq 6H (psi') Seismic Pressure Increment 0.6X Zone �Q I 0.4(1 - xfH) q Surcharge 27 pcf . pressure (Level Backsiope) 1 Bottom. of Exposed Nail H14 o S min 1:1 (rriax. ] k6- pcf ", Active Pressure Passive Pressure H Z Notes: 1 Embedment (Z) should be determined by summation of moments at the bottom of the soldier piles or at ground anchor location if present. Minimum pile embedment shall be 60 feet below Existing Grade (crest of bluff). 2. R factor of safety of 1..5 has been applied to the recommended passive earth Pressure value. Increase allowable passive pressure by 113 for resistance to tranislant loads., including seismic earth pressure. 3. Seismic earth pressure is the incremental value; combine with static active earth pressure. 4. Active, seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three times the diameter of the vertical 'elements. 6. Use uniform earth pressure of 150 psf and 200 psf for lagging design with vertical elements spaced at less than or equal to 6 feet and between 6 and 3 feet, respectively. 7. Refer to report text for additional discussions. Dumas Bay West M.nGE ` ' Reagan Parcel 4342 SW 307th Street I M C O R a 0■ A T H Federal Way, Washington WALL DESIGN PARAMETERS CANTIi! EVER WALL l SINGLE TIEBACK No. 15-098 figure No. i Surface Surcharge = q 2Sq Seismic Pressure Increment ` B, X �. Micro -pile or Soldier Pile Wall ITMITTIT i Existing Grade No -Load 0.5X Zone 60 �. f 18H -� A Q� f 0A(1 - xf") q Bottom of Exposed Wall Surcharge Pressure Hl4 27H psf--- 5 min 27 pcf (revel Backs(ope) + 1:1 (max.) Ij 67pcf- I Active Pressure Passive Pressure Notes: 1, Embedment (Z) should be determined by summation of moments at the bottom of the soldier piles or at ground anchor location if present. Minimum pile embedment shall be 60 feet below crest of Nuff. 2. A factor of safety of 1.5 is 'included in the recommended allowable passive earth pressure value. Increase allowable passive pressure by 113 for resistance to tranisient loads, including seismic earth pressure. 3. Seismic earth pressure is the incremental value; combine with static actbm earth pressure. 4. Active, seismic and surcharge pressures should be applied over the fill width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three times the diameter of the vertical elements. 6. Use uniform earth pressure of 150 psf and 200 psi for lagging design with vertical elements spaced at less than or equal to 6 fast and between S and 8 feet, respectively. 7. Refer to report text for additional discussion and recommendations. PanGE&c o w r o w w s z o Dumas -say West Reagan Parcel 4342 SW 307th Street Federal Way. Washington WALL DESiGN PARAMETERS MULTIPLE TIEBACKS ject No. 15-886 (Figure No. 2 H N 0 50 Igo 1�5.0 290 250 f �z ' mAm ® �- 9 J � 1 Cn , O yl � 1 7 :n 0 §1;3§a aaaan -,wTa I m S cn ca I ° a cn a r w ! is I�•�� a i 1 2 — fD `° o f° = C c = z • T i September 16, 2015 r IUJUUL?V o. 1J^11V Mr. & Mrs. Tom Donovan 30625 4:3rd Avenue SW Federal Way, Washington 99023 Subject: C;eotechnical Engineering Recommendations 30625 43rd Avenue: SW Federal Way, Washington Dear Mr. & Mrs. Donovan, TDar,GE,@ L l a {I P f: :. T E S l oCtechnicO Pal & Earthquake Engineering Consultants RESUBMITTED SEP 18 2015 CITY OF FEDERAL WAY CDS po»l1Fll Tun /per»!�1<+(�ll Yarn»oral fHic lnttnrrn»nYtY+rnca»1i»iY nYw irontorT+»Ynor i uiavi.av, uiv. `a u,i�vir f Yivrr�s�vu �uav iv��i ivTrv�� rr.�vuvu�sicb vu bvv�vvi«iivur engineering design recommendations for a slope stabilization wall to be constructed at the crest of the bluff on the north side of the subject residential property. The purpose of this wail is to provide long-term protection from mass wasting and slope retrogression at the crest of the coastal bluff that is experiencing sloughs and landslides to the north and below the subject residence. This letter report is supplemental to the geotechnical engineering study report that was prepared by PanGEO titled Dumas Bay West Coastal Bluff Stability Evaluation, and dated July 16 2015 to address the overall gectecl'u .cal condit.o» ofthe coastal b1Y,zfftl:at �� runs along the northern (real) portion of all the Dumas Bay West Homeowners (DBWM properties. Please refer to that report for a discussion of the geologic, groundwater and Y Y •.• r n • Y Y A geotechnicar conditions ofthe Dr) 'ri properties, including the subject parcel. discussion is provided in the coastal bluff stability report (PanGEO, July 16, 2015) regarding the field explorations, laboratory testing program, geotechnical slope stability analyses and conclusions regarding the stability of the coastal bluff that flares the northern side of the DBWH properties. Retaining Wall Purpose and TDecign RPenmmendatinns The concept of the retaining wall recommended herein is to provide a structural system at the crest of the coastal bluff that can be retrofitted in the future according to the volume of mass wasting (sloughing or landsliding) that occurs below the wall in response to cOnt;nYaed coastal eros,an processes. Upon the cvmplet;cn of the ;n.tial constmwtacn, 3213 Easiiake Avenue E. Suite B Seattie, WA 99102 (206) 262-03 0 FAX (206) 262-0374 Page 2 r� Project No. 15-116 September 16, 2015 there will be little or no exposed face of wall. Slope movements below the wall may then be allowed to occur until a pre -determined height of the wall is exposed that requires retrofitting to increase the lateral resistance of the system. Up to this pre -determined height, lagging or facing elements will need to be installed to prevent caving of retained soil from between the vertical elements. The system. may be comprised of c-onVentinmal soldier piles that can f inctlon m pure cantilever up to a pre-Bete—Unined lirrliting height according to the structural moment resistance of the system. If slope movements expose a portion of the soldier piles, conventional lagging should be provided . if S10pe lllove111e11ts 1io11t111Ue `Lo eliliose the wall such that the pre -determined limiting height is reached or exceeded, additional lateral restraint should be provided for the wall system in the form of permanent ground anchors (tiebacks). A second and possibly third pre -determined height of exposed wall s1101i1d also be. identif e.d when additional rowk) of tit- ;q cs are. required, The pre- determined heights and retrofit action required should be identified on the structural drawings for the wall. The system may also be comprised of micropiles with vertical elements at the location where a wall face would be constructed in the future, but also tied -back with a battered micro -pile connected by a grade beam to add lateral resistance to the system and provide for a taller exposed height before addition of tiebacks for additional lateral resistance is required. Limiting heights and retrofit requirements should be shown on the structural drawings similar to the soldier pile option described above. Figure 1 (attached) provides lateral earth pressures that may be used for structural design of either of the systems described above with a single point of lateral restraint, or for pure cantilever ol, a soldier pile system. rigure 2 (also aaacned) provides lateral earth pressures that may be used for structural design of the retrofit options for multiple rows or lateral restraint elements (tiebacks). The minimum embedment length for the vertical elements (soldier piles) should be 50 feet. The surcharge load shown in bath figures is generic and need not be ainnplied if ciircharge loading ig not present. Global Stability A small portion of the retaining stricture may retain up to 6 feet of new backfill in the vicinity of the existing deck. Figure 3 presents the results of global stability analysis with the. incJiusion of the retaining structure as a soldier pile. and the inr_.remental increase in loading due to the new backfill. The stabilization provided by the soldier pile increases 15-116 DBW Parcel 6 Wall Design Recommendations final.doex PanGEO, Inc. Page 3 Project No. 15-116 September 16, 2015 the overall global stability to 1.58 from 1.48 as compared to the existing condition (Figure 7 from PanGEO. July 16. 2015). Tiebacks The manner in which the tieback anchors carry load will depend on the type of anchor selected, the method of installation, and the soil conditions surrounding the anchor. Accordingly, we recommend use ofaperformance speciricabon requiring the coniracior to install anchors capable of satisfactorily achieving the design structural loads, with a pullout resistance factor of safety of 2.0. For planning purposes, however, the anchors may be sized for an allowable skin friction value of 2.5 kips per lineal foot of anchor bond lena h, assuming that small riiam�tPr (ahniit Fj inrhPcl r�rP�ciirP-arnntP.r� tiahark- �x�ih it a-.»ed._. be used. Post -grouting may also be needed in order to achieve the design capacity. We recommend that the allowable tieback loads be limited to about 90 kips per anchor. The tiebacks for this project should be installed by experienced personnel. Temporary casing may be required to prevent excessive ground loss. in addition, the use of compressed air to flush the drill cuttings must be properly controlled; the use of excessive amount of comnressed air while drilling tiebacks could lead to reduction of soil strength and ground movements. J1Lh M%1�5<4LV1 j. Ae2p Vl1test LThe LVLual capacity of L>1v LSVhVIs JhVu1d be check least one 200% test should be performed prior to installing production anchors. All production anchors should be proof tested to 150% of the design load. The anchor instaiiations should be conducted in accordance with the latest edition of the Post Tensioning Institute (PTI) "Recommendations for Prestressed Rock and Soil Anchors". Elements of the testing are as follows: Verification Tests (200% Tests) • Prior to installing production anchors, perform a minimum of one test each on each anchor type, installation method and soil type with the tested anchors constructed to the same dimensions as proposed production anchors. ■ Test locations to be determined in conjunction with, and approved by, the geotechnical engineer. + Test anchors, which will be loaded to 200% of the design load, may require ,t,t'+; ,w ,t .. v� .;... + t i�+v t t , a + + a ono/+�, t+; auuiL,ona, preSL,�a�Li,� steel "steel loan ,�oL w exceed v �o vs L_,e ultimate tensi e strength) or reinforcing of the reaction soldier- pile. 15-116 DBW Parcel 6 Wall Design Recommendations final.doex PanGEO, Inc. Pape 4 l ' Project No. 15-116 Sente..11 ber 16, 2015 — • Load test anchors to 200% load in 25Uio design load increments, holding each incremental load for at least 5 minutes and recording deflection of the anchor head at various times within each hold to the nearest 0.0finch. • At the, 2000/- lead the, holding nerinri shall lie, at least 60 minas teC. • A successful test shall provide a measured creep rate of 0.04 inches or less at the 200% loadbetween I and 10 minutes, and 0.08 inches or less between 6 and 60 lCULlutes, wnd a l th-ne 11111e111e11iJ jlittil li"ttYG it cleel f a- 'tttIhat is 1111ea1 l)r t1Gli1GtL�liig with time. The applied load must remain constant during all holding periods (i.e. no more than 5% variation from the specified load). Verification tested anchors not meeting.the acceptance criteria. will require a redesign by the contractor to achieve the acceptance criteria. Proof Tests 150% load tests on ail reduction anchors • Load test all production anchors to 150% of the design load in 25% design load increments, holding each incremental load until a stable deflection is achieved (record deflection of the anchor head at various times within each hold to the Dearest 0.01 inch). • At the 150% load, the holding period shall be at least 10 minutes • A successful test shall provide a measured creep rate of 0.04 inches or less at the 1 JV 70 IUdll betWGell 1 allll 1 V IIl1I1l3teS W1tIi a GIGe(J rate tIl'dt 1S 1111ear VI" UCG1easllig with time. The applied load must remain constant during the holding period (i.e., no more than 5% variation from the 150% load). Anchors failing this proof testing creep acceptance criteria may be held an additional 50 minutes for creep nleasurernent. Acceptable perfol finance would equate to a creep of 0-08 inches or less between 5 and 50 minutes with a linear or decreasing creep Tate. in the tieback construction, a.bond breaker shall be constructed in the no load zone when the installation procedures use single stage grouting. As discussed above, the structural design of the retaining wail- should" include pre- determined height(s) of exposed wall that would require installation of additional tiebacks if slope movements below the wall result in exposure of wall face. Installation of tiebacks in the future should be accomplished as soon as possible after observation that exposed —nil heightu iiare eYiveeded file pro=deteiiiieiied limits a^�d uhvuld fvllo`r'J the installation and testing criteria recommended above. 15-116 DBW Parcel 6 Wall Design Reconnnendations final.docx PanGEO, Inc. Page 5 Project No. 15-116 September 16, 2015 Wall Backfill and Compaction Wall backfill is considered non-structural as no structure loads are anticipated above the wall backfill zone andp the area will be re -landscaped following wall construction. Wall ba-1,411 may LherviVre consist Vf 0--e:�ca- al- -1 111ate11LL1 provided iL Can. 1�Je i�.J l[LVed compacted to a finis and non -yielding or non -pumping condition, as determined in the field by a representative of PanGEO. The on -site soils may have fines contents high enough for the soils to be moisture sensitive. As such, any soil that is planned for reuse as wall backfill should be stockpiled and protected with plastic sheeting to prevent softening from rainfall. Baseline Survey and Monitoring Ground movements are expecied its be relatively small as a result of wall con siruciion activities since most of the construction will not result in an initial exposed wall face. However, existing structures or improvements to be saved that are near the construction zone should have baseline physical location data established prior to beginning work. As a minimum, optical survey points (points known, or PK's) should be established at the corners of existing features to remain. The selection of monitoring points should be made with concurrence of the geotechnical engineer. The monitoring program should include measurement of changes in both the hori?ontal and vertical directions. The monitoring should be performed at least weekly while active wall construction is underway. The monitoring should be by a licensed surveyor, and the results be promptly submitted to the geotechnical engineer for review. The resullts of the monitoring will allow the design team to confirm design parameters, and for the contractor to make adjustments to means and methods of construction, if necessary. A post -construction baseline survey o tthe wall should also be made so that in the event that ffiture slope movements below the wall occur there is a record of the original wall, construction location for comparison purposes. 15-116 DBW Parcel 6 Wall Design Recommendations final.doex PanGEO, Inc. r agc v Project No. 15-116 CPrtP.illMP.r �� 7n�5 tv,(fi[,Cf-[ICC[Uii (.illi�illGSilliUifS ...:» COISid •eFlo cr re --A .rtne #rase++i.�re � 1ViiV YY iiib Jl1V lAiu VV lK1'�Vii iiil.v UiV�r aVi� during the desibi� Wl\.4 VV1iJY.y KV�'>V;� V1 the retaining structure described herein: 1. Based on the groundwater level measurements taken in the borings drilled for the DBWH (PanGEO, July 16, 2015), groundwater is not expected to be encountered during construction of verticai elements (soldier piies)-or for tiebacks (if needed'). 2.. Care should be taken during construction to not unnecessarily place live load surcharges close to the crest of the bluff as this could result in local instability. 3. Upon completion, grades between the retaining structure and the residential etrl:ctI.,Te s-houlk oe returned to similar conditions as before constructlor: Luc that surface water runoff is not directed over the wall and onto the steep slopes below the coastal bluff. '+. VV a ief:Vmine1LU thiat LLLC followin s11VUlU UG LL1t:.V11)QlaLGU UItU LIM PIUJCI%L plans and specifications: • The geotechnical engineer shall verify the suitability of all soldier pile and tieback holes before concrete or a oo-1 i placement; • Temporary casing should be used if caving occurs as determined by the geotechnical engineer; • T remie methods snail be used for concrete or grout placement in all holes having 3 or more inches of accumulated water; and 6 All soldier pile holes shall be drilled and filled with concrete on the same day. + The geotechnical engineer shall witness and validate verification and proof testing of tiebacks and confirm that test results meet acceptance criteria. 5. PanGEO should review the contractor's submittal for the construction sequence narrative and description including equipment list and key personnel to verify that the contractor's an roach does not adversely affect site conditions or slope stability during construction. V. [ i leprV, '1,(�+ Ve f1o1 11 a AJLO s11V lLld 1}e Vxt J1tV dllA A;l. CO- 1.�V L>,o>?; �V 1 V #;yV; slope stability conditions and to confirm that wall construction is consistent with design parameters and assumptions. 15-116 DBW Parcel 6 Wall Design Recommendations final.docx PanGEO, Inc. Page 7 Project No. 15-116 September 16, 2015 If you have any questions, or require additional information, please contact our offices at (206) 262-0370. Sincerely, r 9 Robert E. Kimmerling, P.E. Principal Engineer Attachments: Figure 1 — Wall Design Parameters, Cantilever Wall / Single Tieback Figure 2 — Wall Design Parameters, Multiple Tiebacks Figure 3 — Static Global Stability Analysis, Section `C' - with Soldier Pile and Backfill 15-116 DBW Parcel 6 Wall Design Recommendations_final.docx PanGEO, Inc. Surface Surcharge = q B X Micro -pile or Soldier.P.ile mall 1 Existing Grade f 0.5X Edo No -Lop Zane 2BQ 0.4(1 - x/H) q Bottom of Exposed Wall 6H (psf) Surcharge 27 pcf H/4 Pressure (Level Backsiope) 5' min Seismic Pressure In r m n 1:1 (max.) 67 pcf Active Pressure Passive Pressure T Z Notes: A. Embedment (i) should be determined by summation of moments at the bottom of the soldier piles or at around anchor location if present. Minimum pile embedment shall be 50 feet below Existing Grade (crest of bluff). 2. A actor of safety of 1.5 has been applied to the recommended passive earth pressure value. 4ncmase allowable passive pressure by 1/3 for resistance to tranisient loads, including seismic earth pressure. 3. Seismic earth pressure is the incremental value; combine with static active earth pressure. 4. Active, seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three times the diameter of the vertical elements. 6. Use uniform earth pressure of 150 psf and 200 psf for lagging design with vertical elements spaced at less than or equal to 6 feet and between 6 and 8 feet, respectively. 7. Refer to report text for additional discussions. �� 01,� �;7� I N C O R P O R A T C O Dumas Bay West Donovan Parcel! 30625 43rd Avenue SW Federal Way, Washington WALL DESIGN PARAMETERS CANTILEVER WALL! / SINGLE TIEBACK °' 15-116 6 m Oc 0 Y U J E E 5 Lf W Surface Surcharge = q 6H (psf) Seismic Pressure Increment B- x "Oicro-pile or Soldier Pine Wall Existino Grade t7.57C RP_Load 600 zone 213q �- 18H OA(1 - x/H) q Surcharge Pressure 27H psf 27 PC, f (Level Backsiope) 5' min 1 ' I� Active Pressure Bottom of Exposed Wall ti 1:1 (max.) 67 pcf P ur Notes: 1- Embedment (Z) should be determined by summation of moments at the taottcm of the soldier piles or at around anchor location if present. Minimum pile embedment shah be 50 feet below crest of bluff. 2. A factor of safety of 1.5 Is included in the recommended allowable passive earth pressure value. Increase allowable passive pressure by 113 for resistance to tranisient loads, including seismic earth pressure- 3. Seismic earth pressure is the incremental value; combine with static active earth pressure. 4. Active, seismic and surcharge pressures should be applied over the full width of the pile spacing above the base of the excavation, and over one pile diameter below the base of the wall face. 5. Passive pressure should be applied to three times the diameter of the vertical elements. 6. Use uniform earth pressure of 150 psf and 200 psf for lagging design with vertical elements spaced at less than or equal to 6 feet and between 6 and 8 feet, respectively. 7. Refer to report text for additional discussion and recommendations. Dumas Bay West RnGE&Donovan Parcel A t 0 A' 0 01 AA T t 0 34625 43rd Avenue SW Federal Way, Washington WAIL DESIGN PARAMETERS MULTIPLE TIEBACKS 15-116 (Figure No. 2 H z -�a - l as - 150 _ - - zo� � A41 11 it i i k ilp e� R D a 3 a CD � m f1 .r � O In lWi'� �s 0 0 rt 0 0 S m G C S gC C <i 3 3 3 A' a s � Cr n 0 0 o c ro N 7 G G C fll Ol Ol N lu fro N M C C11 C1 C C n ri n n A ro ro ro ro m 0 0 o o = September 16, 2015 File No. 15-046 Dumas Bay West Homeowners c/o Mr. Carl Jonasson 4346 SW 307d' Street Federal Way, WA 98023 RESUBM11-TE® su 19 Z015 CITY OF FEDERAL WAY CDS PanGE@ I W [ O A a G R A T 6 0 Geotechnical & Earthquake Engineering Consultants Subject: Geotechnical Engineering Study — Final Report Dumas Bay West Coastal Bluff Stability Evaluation — 6 Properties: 4316, 4326, 4338, 4342, 4346 SW 3071h Street & 30625 43rd Ave. SW Federal Way, Washington Dear Mr. Jonasson, The enclosed report contains the results of our geotechnical field reconnaissance and explorations, along with conclusions and preliminary recommendations regarding the steep slopes present on the subject six residential properties. This study was undertaken at the authorization of the Dumas Bay West Homeowners (DBWH) to address and evaluate the stability of the coastal bluff that lies to the north and below the residences of the DBWH. The enclosed report provides the basis for the analysis and conclusions regarding site geology, hydrogeology and slope stability of the six parcels. Other reports or memoranda may supplement this report with recommendations for specific actions that may be employed to improve or stabilize the coastal bluffs on individual parcels of the DBWH. This final report addresses comments received as part of the City of Federal Way's review process as provided in the Geotechnical Review of Documents prepared by Amec Foster Wheeler Environment & Infrastructure, Inc., dated September 1, 2015. A summary of the disposition of the comments is enclosed. Please do not hesitate to call with any questions. !fit Sincerely, =3_ a= cc obey E merling, P.E., L.E.G. Ak- Principal Geotechnical Engineer CD Enclosures: Summary of Comments and Responses Geotechnical Engineering Study 3213 Eastlake Avenue East Suite L3 Seattle, WA 99102-712-7 Tel (206) 262-03 70 Fax (206) 262-0,74 Final GEGTECHNICAL ENGINEERING STUDY Dumas Bay West Coastal Bluff Stability Evaluation Federal Way, Washington RESUBMITTED SEP 18 2015 PROJECT NO.15-046 CITY OF FEDERAL WAY September 2015 CDS Prepared for: Dumas Bay West Homeowners Geateehnieal & Earthquake PanGE@) Engineering Consultants I N C O R P O R A T E D Dumas Bay West September 16, 2015 TABLE OF CONTENTS 1-0 INTRODUCTION................................................................................................................... I 2.0 SITE DESCRIPTION............................................................................................................. 2 2.1 LOCATION AND LAND USES.................................................................................................. 2 2.2 SURFACE CONDITIONS........................................................................................................... 2 2.3 SURFACE WATER MANAGEMENT.......................................................................................... 3 2.4 HISTORICAL AND RECENT MASS WASTING........................................................................... 6 3.0 SUBSURFACE EXPLORATIONS ............ 1........................................................................11 4.0 SUBSURFACE CONDITIONS...........................................................................................11 4.1 SITE GEOLOGY.................................................................................................................... 11 4.2 SOILS................................................................................................................................... 12 4.3 GROUNDWATER................................................................................................................... 13 5.0 SEISMIC CONSIDERATIONS..........................................................................................13 5.1 DESIGN CRITERIA................................................................................................................. 13 6.0 SLOPE STABILITY.............................................................................................................14 6.1 STABILITY ANALYSES......................................................................................................... 14 6.2 DISCUSSION OF RESULTS..................................................................................................... 15 6.3 STABILITY RISKS................................................................................................................. 15 6.4 SURFACE WATER CONSIDERATIONS.................................................................................... 17 7.0 CONCEPTUAL STABILIZATION OPTIONS................................................................17 8.0 ADDITIONAL SERVICES.................................................................................................18 9.0 LIMITATIONS.....................................................................................................................18 10.0 REFERENCES.................................................................................................................... 20 LIST OF TABLES TABLE Page No. Table 1 Summary of Groundwater Measurements....................................................................... 13 Table 2 Seismic Design Parameters per 2012 IBC....................................................................... 13 Table 3 Summary of Slope Stability Analyses and Results.......................................................... 15 15-046 DBWH Geotechnical Study_final.docx i PanGEO, Inc. Dumas Bay West September 16, 2015 LIST OF FIGURES Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Figure 3 Static Global Stability Analysis, Section `A' — Existing Condition Figure 4 Static Global Stability Analysis, Section `A' — Existing Condition at Setback Figure 5 Static Global Stability Analysis, Section `A' — Back -analysis of Section `B' Slide Figure 6 Static Global Stability Analysis, Section `B' — Post -slide Condition Figure 7 Static Global Stability Analysis, Section `C' — Existing Condition LIST OF APPENDICES APPENDIX A FIELD EXPLORATIONS APPENDIX B LABORATORY TESTING 15-046 DBWH Geotechnical Study final.docx ii PanGEO, Inc. I Dumas Bay West September 16, 2015 GEOTECHNICAL ENGINEERING STUDY DUMAS BAY WEST COASTAL BLUFF STABILITY EVALUATION — 6 PROPERTIES: 4316, 4326, 4338, 4342, 4346 SW 307T" STREET & 30625 43RD AVE. SW FEDERAL WAY, WASHINGTON 1.0 INTRODUCTION This report presents the geotechnical exploration, analyses, conclusions and recommendations regarding the coastal bluff located along the north side of each of the six properties included within the Dumas Bay West Homeowners (DBWH) association. The scope of our work included: • Reviewing existing geologic data to gain an understanding of the site conditions, • Performing a site reconnaissance which specifically included noting and documenting the existing stormwater management practices employed on each property, • Conducting a subsurface exploration program consisting of two borings both of which were converted to groundwater observation wells. • Performing slope stability analyses of the coastal bluffs at representative locations, and Preparing the conclusions and recommendations presented in this report. Our work was performed in accordance with our proposal to DBWH, which was authorized on February 27, 2015. For reference purposes in describing various site features, the following nomenclature has been adopted for the six properties of the DBWH for use in this report (west to east): • Parcel 1: 4346 SW 307th Street • Parcel 2: 4342 SW 307th Street • Parcel 3: 4338 SW 307th Street • Parcel 4: 4326 SW 307' Street • Parcel 5: 4316 SW 307th Street • Parcel 6: 30625 43rd Avenue SW The location of the DBWH properties is shown on Figure 1, Vicinity Map and the parcel number convention cited above is shown on Figure 2, Site and Exploration Plan. 15-046 DBWH Geotechnical Study_final.docx 1 PanGEO. Inc. Dumas Bay West September 16, 2015 2.0 SITE DESCRIPTION 2.1 LOCATION AND LAND USES The DBWH properties are all located with street frontage along SW 307t" Street in the Dumas Bay area of the City of Federal Way, Washington. Southwest 307ffi Street is a private street that is not part of the City right of way, which ends at the intersection of SW 307th Street and 43rd Avenue SW at the eastern end of the six DBWH properties. The row of six adjacent DBWH residential properties are bound to the north by Puget Sound, the east and south by other residential properties, and on the west by property owned by the Archbishop Brunett Retreat at the Palisades (Archdiocese of Seattle). 2.2 SURFACE CONDITIONS Surface conditions were observed during site reconnaissance performed by PanGEO personnel on February 15 and March 24, 2015. The overall topographic relief at the site is approximately 150 feet, ranging from the inter -tidal zone at the base of the coastal bluff to the maximum elevation of 150 feet on the westernmost of the DBWH properties. The DBWH properties occupy an east -west trending ridge with the crest at the approximate location of the primary residential buildings on each parcel. From this ridge, the coastal bluffs slope steeply, at gradients exceeding 100 percent, to the north and the beach below. The slopes to the south of the ridge are less steep, varying in slope, and averaging approximately 20 percent extending down to a pond at approximately El. +55 feet. The ridge itself loses elevation from west to east, with a fall of approximately 55 feet from approximately El. +150 feet at Parcel 1 to approximately El. +95 feet at Parcel 6. Further east, the ridge continues to descend down to sea level at the western fringe of Dumas Bay. To the west of the DBWH properties the topography continues to rise gently to moderately an additional 20 to 30 feet onto the Archbishop Brunett parcel. Vegetation consists of mature, tended landscaping on the upland portions of all six DBWH properties. Below the crest of the coastal bluff, vegetation ranges from mature coniferous and deciduous trees with brush and shrub understory to fully denuded slopes within the areas where mass wasting has occurred (discussed further, below). A portion of the slope below Parcel 3 extending east to include Parcel 4 and a portion of Parcel 5 has experienced recent cutting of the vegetative cover on the slope. The cutting has left stumps approximately 2 to 4 feet above the ground surface. An area of recent instability is visible from the beach mid -slope and along the Parcel 3/4 boundary. The slope comprising the coastal bluff from the ridge where the residential structures are sited to the toe of the slope at the beach of Puget Sound was visually observed during the site reconnaissance. This slope differs from other tall coastal bluffs that exist around Puget Sound in 15-046 DBWH Geotechnical Study_final.docx 2 PanGEO, Inc. Dumas Bay West September 16, 2015 several respects. First, the slope is remarkably dry. No evidence of seeps or springs that would contribute to slope instability was noted during the reconnaissance. Second, the slope is less steep as compared to other coastal bluffs around Puget Sound that are comprised of glacially overridden soils. According to the site survey that provides the basis for the topography shown in Figure 2, Site and Exploration Plan, the undisturbed portions of the bluff are approximately at a slope of 100%. Where mass wasting has occurred (discussed further, below), the slopes are flatter, ranging between about 70% and 90%. Locally, notably on Parcel 1, the coastal bluff slope is steeper than 100%, to near vertical, just above the toe of the slope at approximately mean higher high water level. Third, the soils observed in the slope are outwash sands, with some silt layers, capped with a relatively thin glacial till layer at the top of the bluff. No evidence was observed of the overconsolidated clay (locally termed "Lawton Clay", "Seattle Clay" and "glaciolacustrine deposits") that is notorious as a major contributor to landslides around Puget Sound. 2.3 SURFACE WATER MANAGEMENT During the site reconnaissance made on March 24, 2015 the collection and disposition of surface water was visually observed on each of the six parcels. Due to the topography of the ridge upon which the DBWH parcels sit, all surface runoff to the south of the primary residential structures is ultimately routed in a southerly direction and not toward the coastal bluff. The observations are generally organized to discuss surface drainage in the following order: • Surface drainage on the north (rear) side of the primary residence, ■ Disposition of primary residence roof gutter downspouts, • Garage pad surface runoff, • Secondary structure roof downspouts (if any), ■ Driveway runoff, • Other surface runoff or miscellaneous drainage items noted on the south (front) side of the residence, and ■ Underground collection system discharge (if any or known). Observations at each parcel are discussed below. Parcel 1 — On the north (rear) side of the residence surface water collects in a topographic depression below the deck structure between the house and the crest of the coastal bluff. The glacial till cap (discussed in more detail below under Geology and Subsurface Conditions) is for all practical purposes impermeable and therefore water ponds in the depression. Both the depression caused by a slight topographic ridge right at the crest of the coastal bluff 15-046 DBWH Geotechnical Study_final.docx 3 PanGEO, Inc. Dumas Bay West September 16, 2015 (hereafter referred to as the "lip") and ponding on top of the glacial till is a condition that repeats on other parcels as discussed separately, below. When the water level in the depression on this parcel reaches a nuisance level, the homeowner operates a small sump pump to route and discharge the water to the catch basin system on the south (front) side of the residence. All roof gutter downspouts on the primary residential structure are collected in tight lines and routed together into the underground storm drainage system. The garage pad on the south side of the residence is concrete flatwork and directs surface runoff to either a strip drain immediately in front of the garage doors or to a catch basin at the south center edge of the pad. Roof gutter downspouts on the detached garage or shed building discharge to the driveway and collects with the surface runoff from the garage pad. Further surface water that collects on the concrete driveway is contained by edge gutters until it directs the runoff to a strip drain at the driveway entrance (gate) to the parcel. The discharge of the strip drain is uncertain, but at this point the surface drainage is well below the topographic high on the parcel and well away from the coastal bluff. A water feature operates south of the garage pad and flows in a southerly direction to its collection/pump pond. Overflow during heavy precipitation is directed to a cobble/gravel strip drain feature along the eastern property line, which also intercepts other surface runoff from the landscaped areas. This collection area may join the discharge from the underground storm drain system, or infiltrate, or combine with the strip drain at the end of SW 307th Street. All drainage collected by tight lines and catch basins appear to converge to the low point of the catch basin at the south center edge of the garage pad. The discharge from this point is uncertain, but according to the resident, the system has never clogged or backed up. Parcel 2 — Due to the mass wasting that has recently occurred on the north side of this parcel, the "lip", if there was one, is no longer present and surface runoff is free to flow to the north and over the crest of the coastal bluff. Catch basins are also present closer to the residence that collect surface water into the underground piping system. All roof gutter downspouts on the primary residence are collected into tight line underground piping. There are no secondary structures on this parcel. The garage pad on the south side of the residence is constructed of permeable asphalt and was constructed relatively recently in accordance with modern site development requirements for impermeable surface areas. 15-046 DBWH Geotechnical Study_final.docx 4 PanGEO, Inc. Dumas Bay West September 16, 2015 The driveway is concrete and directs surface runoff to the south and the roadside ditch of SW 307th Street. Landscape walls have been constructed south of the garage and garage pad and one of these walls was observed with a weep hole that was discharging water onto the paved surface of SW 307' Street. According to the resident of Parcel 2, all drainage collected in tight lines is routed to an infiltration gallery located south of the garage. The resident also reports that the infiltration gallery has never overflowed. Parcel 3 — This parcel also exhibits the "lip" at the crest of the coastal bluff that prevents surface water on the north (rear) side of the residence from flowing to the north and a topographic depression similar to that observed on Parcel 1 collects and ponds surface water within a rock garden style landscape feature. No catch basins or other means of collecting this ponded water were noted, although the topography indicates that if the depression overflows, the flow is to the south via the east side of the residence. All roof gutter downspouts on the primary residence are collected into tight line underground piping. There are no secondary structures on this parcel. The garage pad on the south side of the residence is constructed of modular pavers and is therefore considered pervious. A catch basin collects surface runoff at the low point located at the center of the east side of the pad. The driveway is asphalt and drains surface water to the roadside ditch along the north side of SW 307th Street. A manhole cover labeled "Drain" is located about midway down the driveway. This appears to be the collection point for the underground tight line drainage, but the outfall is not known. Two pipes outfall to the roadside ditch at the southeast corner of the property. Neither of the pipes was discharging water at the time of the visual reconnaissance, despite rainfall occurring the previous night. Parcel 4 — Observations of this parcel were limited to what could be seen from the boundaries of the parcel and from the beach below the bluff. The north (rear) of the residence has a combination of concrete flatwork, deck and lawn. The deck is over -hanging the edge of the bluff by several feet and is therefore acting in cantilever. The concrete flatwork extends beneath a deck that overhangs the coastal bluff. These landscape elements appear to allow surface runoff to flow to the north and over the crest of the bluff. The "lip" either never existed on this parcel, or was removed during landscaping and deck construction activities. All roof gutter downspouts on the primary residence appeared to be collected into tight line underground piping. The south side of the residence has numerous landscape walls and a partially underground garage structure. Some of the associated walls are moderately tall and the wall drainage (if 15-046 DBWH Geotechnical Study_final.docx 5 PanGEO, Inc. Dumas Bay West September 16, 2015 any) is unknown. However, due to the decrease in topographic elevation from the primary residence to the south, all surface drainage and runoff is also directed to the south. Parcel 5 — Similar to Parcels 1 and 3, this parcel also exhibits the "lip" at the crest of the coastal bluff that prevents surface water on the north (rear) side of the residence from flowing to the north. The ridge at the bluff is more prominent on this parcel and directs all surface runoff to the south. A water feature (not active at the time of reconnaissance) flows from the north to the south in the landscape area between the residence and the bluff (rear of house). If the water feature overflows during precipitation, the overflow would collect in a depression beneath the deck attached to the rear of the residence. According to the owner, there is a catch basin present near the deck that is hidden in the surfacing of a "dry stream" and that surface water collected there is discharged to the roadside ditch along SW 307th Street. All roof gutter downspouts on the primary residence are collected into tight line underground piping with the exception of the southwest corner of the residence which drains directly to the ground surface via a "chain drain." Although the water that reaches the ground surface at this location is not positively directed away from the structure, the topographic relief ensures that all gutter drainage that reaches this location eventually becomes surface runoff flowing to the south. There are no secondary structures on this parcel. The unpaved driveway, together with the rest of the parcel south of the residential structure, sheds runoff to the south where it is collected into the roadside ditch along SW 307t11 Street. Parcel 6 — Due to the mass wasting that has occurred on the north side of this parcel, the "lip", if there was one, is no longer present to prevent surface drainage from flowing over the crest of the coastal bluff. However, the area between the residence and the bluff is relatively level and may drain slightly to the south where there are several catch basins that collect surface water into the underground piping system. All roof gutter downspouts on the primary residence are collected into tight line underground piping with the exception of one downspout which discharges onto concrete flatwork where flow is then directed into one of the aforementioned catch basins. There are no secondary structures on this parcel. The garage pad and driveway on the south side of the residence is constructed of a combination of concrete flatwork and asphalt and drains via surface flow to the south and east towards the roadside drainage ditches of SW 307th Street and 43rd Avenue SW. 2.4 HISTORICAL AND RECENT MASS WASTING The term "mass wasting" includes landslides, surficial sloughs, debris flows and other occurrences where earth materials, with or without the presence of water, move downhill under the force of gravity. The coastal bluffs north of the residences comprising DBWH are typical of 15-046 DBWH Geotechnical Study_final.docx 6 PanGEO, Inc. Dumas Bay West September 16, 2015 steep slope areas around the Puget Sound region that have experienced mass wasting in the past, both historically and pre -historically. There are two notable areas of mass wasting in the slopes north of the DBWH properties. These are generally located north of and below the residences on Parcel 2 and Parcel 6, although there are some mass wasting impacts that extend laterally onto parcels adjacent to Parcels 2 and 6. Parcel 2 — The recent slope movements below Parcel 2 occurred on January 18, 2015 sometime between mid -day and early evening. The landslide developed on a relatively deep surface as compared to most mass wasting that occurs on coastal bluffs around the Puget Sound. Since the topography of the slope before the slide occurred is not well defined (i.e., by survey, LIDAR or other means) the exact depth of material that was mobilized during the slide is not known for certain. However, based on the volume of material deposited at the beach level and comparisons with neighboring slopes that did not slide, the depth of the failure surface is estimated to be on the order of 20 feet (measured normally into the slope face). A comparison of the cross sections shown on Figure 3 (Section `A', Parcel 1) and Figure 6 (Section `B', Parcel 2) corroborates this conclusion. These movements coincided with a pair of anomalously high tides at approximately 12 noon and 10 pm (see Plate 1). Both of these tides crested nearly a foot above the predicted tide elevation and almost a foot above the mean higher high water (MHHW) elevation of +11.84 feet. At the same time, a storm with sustained northerly to northeasterly winds of approximately 10 knots and gusts to 20 to 30 knots (see Plate 2) produced heavy surf that, when combined with the unusually high tides, created a highly erosive condition at the toe of the coastal bluff. Plate 3 provides the relationships between various vertical datums in use around the Tacoma regions of southern Puget Sound. Note that the vertical datum used as the basis for Figure 2, Site and Exploration Plan is NAVD88, which differs from the tidal datum used in Plate 1. According to the survey that forms the basis for Figure 2, the toe of the coastal bluff is at El. +9 feet. Accounting for the difference between the datums, the tides on January 18, 2015 were at least one foot above the toe of the bluff. Wave action and height above the tide level created a highly erosive condition on the soils exposed at the toe of the bluff. Under these conditions beach erosion is also likely. Also of note is the cumulative rainfall in the days prior to the landslide (see Plate 4). The rainfall amounts were at threshold levels for landslide risk in the Puget Sound region according to research by the U.S. Geological Survey (see Plate 5). The top of the recent slide (head scarp) is over -steepened to near vertical and has several tension cracks behind the main head scarp that may break back or spall off over time. 15-046 DBWH Geotechnical Study_final.docx 7 PanGEO, Inc. Dumas Bay West September 16, 2015 15.0 12.5 10.0 J J 7.5 d C 5.0 t 0.5VSatu,,rday, Jan 17 2015, 12:30 GNT Ictlons: 10.396ft. ntd: 10.577ft. 0.0 00:00 06:00 1/17 1/17 Plate 1: Tide Levels on J NOAAMOSICO-OPS Observed Water Levels at 9446484, Tacoma WA From 201 SMIM 7 00:00 GMT to 2015107M 6 23:69 OW 12:00 18:00 00:00 1117 1/17 1/18 — Predictions — Verified — Preliminary iary 18, 2015 (source: h :Ilwww. NOAAMOM04M w hda of 944"87, To Za W7 WA From 20UMM700:00 OYTto 201dMIM923:59 OUT '5 NOAWn05:CC o CF far OPCf !�CC.il,OQfim}!k Product5"St-- 06:00 12:00 18:00 1/18 1/18 1/18 40 30 20 N semrdnlen i�, ia:sacr4r �rti iir '1] T � � at a W1nds=0,5Skn. from NE [4O1 �+xrc� ;•_ 1,,. Oa rA ❑: �O 12;00 16:00 2000.16. iut W 00 0900 12.00 1600 20.30 k Aids — Gusts NOM/NOSir Nvfmop domiOmampophkPmdu aid S"ms Plate 2: Wind Gusts on January 18, 2015 source: h ://www.iioaa. oy/ 15-046 DBWH Geotechnical Study_final.docx 8 PanGEO, Inc. Dumas Bay West September 16, 2015 TA COMA PUBLIC WORKS VERTICAL DATUMS FIXED DA T UM NGS ELEV 17.454 (1973) — 1920 NGS BENCH MARK CITY OF TACOMA ELEV 17.45 NGS (NGM29) do CITY OF TACOMA DATUM 0.00 NAVDBB DATUM 0.00 i CORPS OF ENGINEERS k PORT OF TACOMA DATUM 0.00 -- -OLD CITY DATUM" 0.00 - (PRIOR TO JULY 1, 1990) M It S 1 TIDAL DA T UM EPOCH 1960-1978 (VARIES ON A 19 YEAR CYCLE) MHHW NI. T MEAN TIDE LEVEL nW mr' m� e� MEAN LOW WATER 7.efi FEET MLLW MLLW (TIDAL DATUM 0.00) MHHW: MEAN HIGHER HIGH WATER MLLW: MEAN LOWER LOW WATER Revised February 2004 using data from uove Maroon, rL� U 5 Army Carps of Engineers, Seattle District Tacoma Public Works Sbufn Puget Sound Region 90 - Tacoma Chief Surveyor phone: 253-541-5772 Plate 3: Tacoma Vertical Datums 15-046 DBWH Geotechnical Study_final.docx 9 PanGEO, Inc. Dumas Bay West September 16, 2015 U.S. Department of Commerce National Oceanic & Atmospheric Administration National Environmental Satellite, Data, and Information Service Elev: 136 ft. Lat: 47.346' N Lon: 122.322` W %AIA - Mue we �+C G41CIer1.1IS1WAK(:OOHA Record of Climatological Observations These data are quality controlled and may not be identical to the original observations. Generated on 04/28/2015 Temperature (F) Precipitation{see ") 24 hrs. er di+ty at 24 Hour Amounts ending At Obs P r at observation O at observation time Time e time b I Y M s i o D e m a a n a r v Rain, F Snow, ice IF Snow, ice Snow, i n r It h y Max, Min. a melted I pellets. I hall, ice on t snow, etc. a hail a ground a (in)9 (in) 9 (In) r i y o n 2015 11 1 0.00 1 0.0 2015 11 2 0.00 0.0 2015 11 3 0.06 2015 11 4 0.15 2015 1 5 0 66 2015 1 6 2015 1 7 007 2015 1 8 T 2015 1 9 0.00 00 2015 1 10 0.18 2015 1 it 2015 1 12 2015 1 13 0.00 10.0 2015 1 14 1a-oa 0.0 2015 1 15 0.00 0.0 2015 1 16 0-42 2015 1 17 0.01 2015 1 18 1 11.25 Plate 4: Rainfall Data for Federal Way prior to Jan. 18, 2015 landslide iimage crooned: source: hM:llwww.ncdc.noaa.govl) rn w 06 z Z 05 — — — Q a 4 1-rLandslides likely U W cc a3 > Cumulative Precipitation Threshold 2 iG P3=3.5•0.67P1; J Landslides _ v 1 unlikely } 00 ' ------- CO 0 1 2 3 4 5 6 7 8 9 10 P15, 15-DAY CUMULATIVE PRECIPITATION BEFORE P3. INCHES Plate 5: Cumulative 3-day and previous 15-day rainfall threshold [for landslides] (Chleborad, et al., 2006 15-046 DBWH Geotechnical Study_final.docx 10 PanGEO, Inc. Dumas Bay West September 16, 2015 Parcels 3/4 — An area of recent instability is visible from the beach mid -slope between Parcels 3 and 4. This sloughing may or may not be related to the removal of vegetation. Parcel 6 — This area has been a location of instability over a number of years. A variety of surface stabilization treatments have been put in place that have been moderately, but not completely, successful in arresting mass wasting processes on the slope. Currently, portions of the slope are covered with jute matting, while other portions remain exposed and un-vegetated leaving them vulnerable to erosion and mass wasting. 3.0 SUBSURFACE EXPLORATIONS Field explorations completed for this study included two borings, both of which were completed as standpipe observation wells. The first boring, designated B-1, was located at the east end of the row of parcels comprising DBWH, near the southeast corner of Parcel 6, and was drilled to a total depth of 101 feet. The second boring, designated B-2, was located on Parcel 2, along the eastern side of the property, and was drilled to a total depth of 140.5 feet. The borings were drilled using a truck -mounted, mud rotary drill supplied by Holocene Drilling of Graham, Washington. Boring B-1 was begun on March 24, 2015, with well completion on March 25, 2015. Boring B-2 was drilled on March 26 and 27, 2015, with well completion on March 30, 2015. Standard Penetration Tests (SPT) samples were taken at intervals of between 5 and 10 feet, as needed to characterize the geologic materials encountered during drilling. The locations of these borings are shown on Figure 2, Site and Exploration Plan. An engineering geologist or engineer from PanGEO was present throughout the field exploration program to observe the drilling, log the materials encountered in the borings, and obtain representative samples from the explorations for laboratory testing. The soils were described in the field in general accordance with ASTM D2488, Standard Practice for Description and Identification of Soils (Visual -Manual Procedure) following the guidelines of the Unified Soil Classification System, as shown on Figure A-1 of Appendix A. Summary logs from the borings are presented in Appendix A as Figures A-2 and A-3. More detailed information about the field exploration program is presented in Appendix A. The results of the laboratory tests are presented in Appendix B. 4.0 SUBSURFACE CONDITIONS 4.1 SITE GEOLOGY According to draft mapping by Troost and Booth (Open File Report, in press), the entire ridge that comprises the six parcels of the DBWH is advance outwash (Qva) deposits with a small cap of glacial till (Qvt) present on top of the ridge. However, older mapping by Luzier (1969) shows 15-046 DBWH Geotechnical Study_final.docx 11 PanGEO, Inc. Dumas Bay West September 16, 2015 the glacial till (Qvt) cap to be much more extensive. Based on our own observations and the materials encountered in the test borings drilled for this study, the mapping by Luzier (1969) appears most representative of the conditions on the six parcels. The glacial till cap is present all along the topographic ridge of DBWH parcels, with the advance outwash deposits exposed in the steep coastal slopes below the bluff. Beach deposits (Qb) are noted in both maps as present along the base of the bluff, consistent with our site observations, but these soils are not a major factor in the analysis and conclusions of this study. Luzier (1969) describes the glacial till and advance outwash materials as follows: Glacial Till (Qvt) — "Compact mixture of gravel and occasional boulders in a gray clayey, silty sand matrix. Includes sand and gravel lenses within and on top of till. Thickness generally 10 to more than 50 feet." Advance Outwash Qva) — "Pebble -cobble gravel... may include very fine sand and laminated silt. Thickness generally less than 100 feet, but may exceed 300 feet in bluffs adjacent to Puget Sound." 4.2 SOILS In general, the soil conditions encountered in the site explorations are consistent with the mapped surface geologic units. The soils encountered in the site borings have been generalized and graphically depicted in two subsurface profiles that were chosen for slope stability analyses (cross sections) and are included as Figures 3 through 7. The soil units identified in both profiles are described below: Unit 1 Fill — Fill was encountered only in boring B-2 at the ground surface where the boring was advanced through planter backfill in a landscape area adjacent to the Parcel 2 driveway. This fill was encountered down to a depth of 5 feet where undisturbed native soils were encountered. Unit 2 Glacial Till vt — The uppermost native (in situ) soils encountered in both borings was dense silty sand with gravel that was moist and massive. This material was encountered to depths of 7'/2 and 35 feet in borings B-1 and B-2, respectively. Unit 3 Advance Outwash va) — Below the Unit 2 glacial till soils, both borings encountered medium dense to very dense silty sand with occasional interlayers of silt that were moist and layered to massive. These soils were encountered to the maximum depths penetrated in both borings. 15-046 DBWH Geotechnical Study_final.docx 12 PanGEO, Inc. Dumas Bay West September 16, 2015 4.3 GROUNDWATER Measurements of groundwater elevations collected to date are presented in Table 1. Table 1 Summary of Groundwater Measurements Well Desi-elation Date of Reading B-EEIeEv. B-2 De th (ft) cl) 2Depth (ft) c►) Elev. (ft) '2) A ril 1, 2015 74 +21 101 +40 Notes; 1. Measurements taken from the top of the monument. 2. Monument elevations of 95 feet and 141 feet for B-1 and B-2, respectively (site survey by DeGross Aerial Mapping, Inc., April 27, 2015)_ 5.0 SEISMIC CONSIDERATIONS 5.1 DESIGN CRITERIA The seismic evaluation of structures should be accomplished in accordance with the 2012 International Building Code (IBC). The IBC seismic design parameters are in part based on the site soil conditions and site classifications. Based on 2012 IBC and the publication ASCE 7-02, it is our opinion that Site Class C is appropriate for the project site based on borings B-1 and B-2. The Table 2 below provides seismic design parameters for the site that are in conformance with the 2012 edition of the International Building Code (IBC), which specifies a design earthquake having a 2% probability of occurrence in 50 years (return interval of 2,475 years), and the 2008 USGS seismic hazard maps: Table 2 Seismic Design Parameters per 2012 IBC Spectral Spectral Site Acceleration Acceleration at Class at 0.2 sec. (g) 1.0 sec. (g) Ss S1 C 1 1.322 1 0.509 Design Spectral Control Site Response Periods Coefficients Parameters (sec.) Fa I F„ I SDs I SD1 I To , Ts 1.00 E 1.30 1 0.881 1 0.441 1 0.10 10.50 15-046 DBwH Geotechnical Study_final.docx 13 PanGEO, Inc. Dumas Bay West September 16, 2015 6.0 SLOPE STABILITY 6.1 STABILITY ANALYSES Global slope stability analyses were conducted to evaluate the stability of the coastal bluff and shoreline slope to determine if the slopes had adequate factors of safety for the site conditions or if stabilization would be required to reduce risk to the residences of DBWH. Based on the topography of the site as shown on Figure 2, Site and Exploration Plan, three sections were selected for analysis and are denoted `A', `B' and `C' on Figure 2. The first section (Section `A') is located across the long axis of Parcel 1 and was selected on the basis of being the tallest overall slope in an un-failed condition along the DBWH properties. Figure 3 depicts the cross section geometry and subsurface conditions based on boring B-2. Figure 3 shows the critical failure surface and factor of safety at this location. A second analysis was performed with the search limit fixed at the setback location of the residential structure on Parcel 1 and is shown on Figure 4. Section `A' was also selected for back -analysis of soil shear strength at the time of the recent mass wasting on the adjacent parcel represented by Section `B'. A nominal amount of beach erosion and bluff undercutting was included based on tidal and surf conditions on the day of failure as described above. This geometry is shown on Figure 5. This analysis validates the soil shear strength used in all other analyses as well as confirming the impact on stability of toe undercutting and beach erosion. The second section (Section `B') is located across the long axis of Parcel 2 where the most recent mass wasting occurred. This section also closely corresponds to the location of test boring B-2. Figure 6 depicts the cross section geometry and subsurface conditions based on boring B-2 and the computed post -failure factor of safety for the critical large-scale failure surface. Note that lower factors of safety are probably for local considerations of stability such as at the location of the tension cracks at the top of the section. The third section (Section `C') is located through the axis of the previous mass wasting that has occurred below Parcel 6 and was selected on the basis of previous mass wasting and also proximity to test boring B-1. Figure 7 depicts the cross section geometry and subsurface conditions based on boring B-1 and the computed factor of safety for the critical failure surface at this location. All analyses were completed using the computer program SLIDE v.6, by RocScience. In general, both circular and non -circular failure surfaces were checked for each analysis performed. However, non -circular surfaces generally yielded slightly lower factors of safety, even when approximating circular surfaces, so these are the results that are reported. 15-046 DBWH Geotechnical Study_ inal.docx 14 PanGEO, Inc. Dumas Bay West September 16, 2015 6.2 DISCUSSION OF RESULTS Table 3 summarizes the factors of safety computed from the slope stability analyses described above. Generally speaking, slope stability factors of safety should be above about 1.25 to 1.3 for permanent slopes that do not directly support a critical structure. Table 3 Summary of Slope Stability Analyses and Results Location Condition Factor of Safety Section `A' (Figure 3) Existing condition for Parcel 1 1.12 Section `A' (Figure 4) Failure surface at setback of existing structure on Parcel 1 1.24 Section `A' (Figure 5) Back -analysis of incipient failure condition on Parcel 2 0.99 Section `B' (Figure 6) Post -failure on Parcel 2 1.50 Section `C' (Figure 7) Existing condition for Parcel 6 1.48 The near -unity factor of safety calculated for the back -analysis conducted at Section `A' (Figure 5) provides a validation of the soil shear strength parameters used in the other analyses as well as supporting the conclusion that significant beach erosion and undercutting occurred during the abnormally high tides and heavy surf that coincided on the day of the failure at Parcel 2 (discussed further above under section 2.4 Historical and Recent Mass Wasting). The higher factors of safety reported in Table 3 are associated with slopes that have seen previous movement and are therefore generally less steep than adjacent slopes which have not experienced recent movement. An exception is the near vertical head scarp on Parcel 2 which continues to exhibit tension cracks behind the head scarp that indicate the locally over -steepened condition is still at risk of breaking back further. At these locations the local factor of safety is likely near unity. While greater than unity, the computed factors of safety for slopes that have not experienced recent failure are marginal relative to commonly accepted design values. 6.3 STABILITY RISKS The relative risks of slope instability identified during this evaluation are discussed on a parcel - by -parcel basis below in this section. It should be noted that all construction near or adjacent tc earthen slopes presents some risk of instability and that where "low risk" is identified, it should not be considered to mean "no risk". Parcel 1 — As indicated in Figures 3 and 4, the computed factors of safety for the slopes below this parcel are marginally acceptable. Since this parcel has the tallest overall slope between the 15-046 DBWH Geotechnical Study_final.docx 15 PanGEO, Inc. Dumas Bay West September 16, 2015 building site area and the beach, combined with a relatively steep slope angle, the relative risk of potential future instability is considered highest for this parcel relative to the other parcels that are subjects of this evaluation. Parcel 2 — The recent mass wasting below this parcel has resulted in a slope configuration that is overall in a more stable condition than it was prior to failure, as can be seen from the relatively high factor of safety computed as shown on Figure 6. This result reflects the stability at a setback behind the tension cracks near the over -steepened condition at the top of the slide area (head scarp). However, the head scarp and tension crack area remains vulnerable to additional movements as the soil between the head scarp and tension cracks behind the head scarp lose strength and seek a more stable configuration by moving downhill. Over time, unless this condition is improved, the remaining setback between the top of slope and the residential structure could be lessened to the point that the structure is in imminent danger and would require emergent measures to protect the structure. Continued erosion of the slide mass that is now resting on the beach will also tend to reduce the overall global factor of safety as the buttressing effect of this material is removed. Parcel 3 — Due to the setback distance between the crest of the bluff and the residential structure on this parcel, the risk to the structure from a large scale movement similar to the recent movement on adjacent Parcel 2 is considered moderate. However, this parcel has two factors that increase the relative risk. The first is the proximity to the failed area below Parcel 2 and the potential for the mass wasting to propagate eastward and affect Parcel 3. The second factor is the denu� dation that has recently occurred on adjacent Parcel 4 that also extends partially onto )Parcel 3. As the root masses die off, the stabilizing effect will diminish and increase the potential for slope movements. Parcel 4 — The denudation of stabilizing vegetation has occurred over most of the extents of the coastal bluff slopes below this parcel. The potential for slope movements will likely increase as the stabilizing effect provided by the root masses diminishes. Setback risks are similar to Parcel 3 and considered low to moderate for the primary residential structure, although the deck that overhangs the coastal bluff is at risk of losing stability at virtually any time. Parcel 5 — This parcel has the largest setback distance between the crest of the bluff and the residential structure of all the parcels that are the subject of this evaluation. The risk of mass wasting affecting the residence is considered low. Parcel 6 — Although the setback distance from the bluff to the residential structure is relatively large on this parcel, the evidence of relatively recent slope movements indicates that mass wasting is more active in this area, which increases the risk relative to the adjacent parcel(s). The risk of additional slope movements that could impact landscape areas is considered relatively high, while risk to the residential structure itself remains relatively low. 15-046 DBWH Geotechnical Study_ inal.docx 16 PanGEO, Inc. Dumas Bay West September 16, 2015 6.4 SURFACE WATER CONSIDERATIONS A discussion of the existing surface water management on each of the six parcels that are the subject of this report is provided in section 2.3, above. Based on the observations reported in section 2.3, it is generally concluded that surface water management practice is good on all of the properties and that poor control of surface water runoff is not a significant contributing factor to the mass wasting processes discussed and analyzed herein. Additionally, the groundwater level below the existing ground surface is sufficiently deep that infiltration and groundwater mounding are not considered significant as related to mass wasting occurrences on the coastal bluff slopes. No specific deficiencies in surface water management practices were noted, and therefore no recommendations for improvement to surface water management practices are deemed necessary. 7.0 CONCEPTUAL STABILIZATION OPTIONS Several options are available that would improve the stability of the coastal bluff. These options generally fall into categories of a) work solely along the base of the bluff, b) work solely along the crest of the bluff, and c) work that extends from the crest of the bluff down the slope face to at or below the high water level. Measures that could be put in place along the base of the bluff include bulkheads and similar structures that would reduce the erosion and undercutting of the slope by wave and tide action. To be effective, such erosion protection structures would need to be continuous along the entire slope below the six DBWH parcels and should be embedded a sufficient distance below the mean higher high water elevation to prevent undercutting by wave and tide action or beach erosion. In order to safely construct this type of structure at the base of a steep slope, work should only proceed in small slot cuts that will not trigger slope movement. Structures could be constructed along the crest of the bluff that would protect the residential structures from future slope movements. It is considered feasible that a wall -type structure could be built that would stabilize the ground behind the wall and protect the residential structure(s) even if slope movement occurs below the wall. Stability of the slope could also be improved by surficial and/or shallow surface treatments that extend from the crest to the base of the slope. This type of slope stabilization would employ passive elements such as soil nails combined with surface stabilization and erosion protection in the form of mats or meshes attached to the heads of the passive elements. A major drawback to this approach is that it requires denudation of the existing vegetation over the entire slope face in order to put the surface treatment in place. Another risk for this option is that wave and tide action could still potentially undercut and destabilize the toe of the treatment. 15-046 DBWH Geotechnical Study_final.docx 17 PanGEO, Inc. Dumas Bay West September 16, 2015 8.0 ADDITIONAL SERVICES This evaluation of coastal bluff stability is intended to form the basis for recommendations that could improve the stability of the slopes on the subject residential parcels. To facilitate construction permitting, geotechnical engineering recommendations for stabilization measures will be provided as supplements to this report according to the risks identified on each parcel and the desires of the individual property owners. Specifically, we anticipate that the following additional geotechnical engineering services may be needed: • Parcel -specific reports or technical memoranda that provide design recommendations unique to the parcel • Construction support services for geotechnical improvements e Other consultation as may be required during construction 9.0 LIMITATIONS We have prepared this report for use by the Dumas Bay West Homeowners. Recommendations contained in this report are based on a site reconnaissance, a subsurface exploration program, review of pertinent subsurface information, and our understanding of the goals and aims of the Homeowners. The study was performed using a mutually agreed -upon scope of work. Variations in soil conditions may exist between the locations of our explorations and the actual conditions underlying the site. The nature and extent of soil variations may not be evident until construction occurs. If any soil conditions are encountered at the site that are different from those described in this report, we should be notified immediately to review the applicability of our recommendations. Additionally, we should also be notified to review the applicability of our recommendations if there are any changes in the project scope. The scope of our work does not include services related to construction safety precautions. Our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. Additionally, the scope of our work specifically excludes the assessment of environmental characteristics, particularly those involving hazardous substances or wetlands. PanGEO does not employ mold consultants nor are our recommendations to be interpreted as being preventative of mold development. A mold specialist should be consulted for all mold -related issues. This report may be used only by the client and for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both off and on -site), or other factors including advances in our understanding of applied science, may change over time and could materially affect our findings. Therefore, this report should not be relied upon after 24 months from its issuance. PanGEO should be notified if the project is delayed by more than 24 months from the 15-046 DBWH Geotechnical Study_final.docx 18 PanGEO, Inc. Dumas Bay West September 16, 2015 date of this report so that we may review the applicability of our conclusions considering the time lapse. It is the client's responsibility to see that all parties to this project, including the designer, contractor, subcontractors, etc., are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the contractor's option and risk. Any party other than the client who wishes to use this report shall notify PanGEO of such intended use and for permission to copy this report. Based on the intended use of the report, PanGEO may require that additional work be performed and that an updated report be reissued. Noncompliance with any of these requirements will release PanGEO from any liability resulting from the use this report. Within the limitation of scope, schedule and budget, PanGEO engages in the practice of geotechnical engineering and endeavors to perform its services in accordance with generally accepted professional principles and practices at the time the Report or its contents were prepared. No warranty, express or implied, is made. We appreciate the opportunity to be of service to the Dumas Bay West Homeowners. Please feel free to contact our office with any questions you have regarding our study, this report, or any geotechnical engineering related issues pertaining to the site. Robert E. Kimmerling, P.E., L.E.G. Principal Geotechnical Engineer a F] STEPHEN W EVANS �V-� Stephen H. Evans, L.E.G. Senior Engineering Geologist 15-046 DBWH Geotechnical Study_final.docx 19 PanGEO, Inc. Dumas Bay West September 16, 2015 10.0 REFERENCES AASHTO, 2012. LRFD Bridge Design Specifications, 6`h edition, American Association of State Highway and Transportation Officials Chleborad, A.F., Baum, R.L., and Godt, J.W., 2006. Rainfall thresholds for forecasting landslides in the Seattle, Washington, area—Exceedance and probability: U.S. Geological Survey Open -File Report 2006-1064. Luzier, J.E., 1969, Geology & Groundwater Resources of SW King Co., WA, Water -Supply Bulletin No. 28 International Building Code (IBC), 2012, International building code: Country Club Hills, Ill., International Code Council, Inc., 690 p. Troost, K. G. and Booth, D. B., in press, Geologic Map of the Tacoma North 7.5' Quadrangle, King and Pierce Counties, WA, USGS Open File Report Washington State Department of Transportation (WSDOT), 2014, Standard Specifications for Road, Bridge, and Municipal Construction M 41-10: Washington State Department of Transportation. Washington State Department of Ecology, 2012, Stormwater Management Manual for Western Washington: Report prepared by the WSDOE, August 15-046 DBWH Geotechnical Study_fmal.docx 20 PanGEO, Inc. FIGURES LL d tC F)mGE(D U 0 I N C O R P O R A T E D r Approximate Scale 1/2 mile Dumas Bay West SW 307t" Street Federal Way, Washington "42 5241 5240 VICINITY MAP :ect No. - -:ure P :. 15-046 1 cn 0 1'I fD Q. to�wd v N � NO o 3 (D C 7 rt .N+ O 7 w I 50 210 2�O a � A mA y P mO m 0 s v N cD a N N � W CO) Zr M CD 0 U O 7 -50 a N O -•• O co (D n O N Ul cr CA _y Q► o - �' CO) D 0 N f/i w W � o a ID HOE 5O 100 200 0 50 ,vu -� NI CD fD CA rt O n � N cr rt �* T N � a Z CD w C 3 COD = w a .� :+ N O Vi 7 0) ■ <fu 3 O — rD O M C DZi ro 7 NO C C2 IA Lnn Ln �p ww 0 0 0 .yr 0 n °c c 0 c z O _ O O Cl 9 Q Q ff (D VI N cr� O 0 0 N N O N 00 N f w 11) N N f�D N In V1 (n N N N N M N fD O O 0 2 7 7 7 N d N m O U1 O 1 APPENDIX A FIELD EXPLORATIONS Dumas Bay West September 16, 2015 APPENDIX A: FIELD EXPLORATIONS This appendix presents factual and interpretive results of our exploratory drilling program. The descriptions of the materials encountered in the subsurface explorations are based on the samples extracted from the borings. The sample descriptions are augmented by observation of the drilling action and drill cuttings brought to the surface during field operations. The paragraphs below describe the field operations and sampling procedures used during the geotechnical field explorations. FIELD EXPLORATIONS The subsurface exploration program consisted of drilling two test borings for the purpose of identifying the subsurface materials, stratigraphy and groundwater conditions along the coastal bluff beneath the residential properties along SW 307"' Street in Federal Way, WA. The two borings (B-1 and B-2) were drilled by Holocene Drilling of Puyallup, Washington, using a truck mounted drill. The borings were advanced using a mud rotary drill string. Both borings were completed as stand -pipe groundwater observation wells. Boring B-1 was located on the easternmost property of the Dumas Bay West homeowners, in the driveway area on Parcel 6, 30625 43`d Avenue SW. Boring B-1 was begun on March 24, 2015 and was advanced to a total depth of 101 feet below the ground surface on March 25, 2015. The boring was completed as a 2-inch diameter stand -pipe groundwater observation well with a screened interval from 80 to 100 feet below the ground surface and a sand pack from 60 to 100 feet below the ground surface. Boring B-2 was located toward the west end of the Dumas Bay West homeowners, in a planter area on Parcel 2, 4342 SW 307t' Street. Boring B-2 was begun on March 26, 2015 and was advanced to a total depth of 140.5 feet on March 27, 2015. On March 30, boring B-2 was completed as a 2-inch diameter stand -pipe groundwater observation well with a screened interval from 110 to 140 feet below the ground surface and a sand pack from 90 to 140 feet below the ground surface. Standard Penetration Tests (SPT) samples were taken in both borings at intervals of between 5 and 10 feet, as needed to complete the borings and characterize the sediments. The locations of these borings are shown on Figure 2, Site and Exploration Plan. A representative of PanGEO logged the test borings and collected from samples from the borings at selected intervals. The locations of the borings were noted using identifiable site features and are shown approximately on Figure 2, Site and Exploration Plan. 15-046 DBWH Geotechnical Study_final.docx A-1 PanGEO, Inc. Dumas Bay West September 16, 2015 SAMPLING METHODS Standard penetration tests (SPT) were taken at 5- and 10-foot intervals, starting at 10 feet below the ground surface after clearing the upper 10 feet with a vactor truck. A SPT test consists of advancing a 2 inch outside diameter (OD), steel, split spoon sampler 18 inches into the undisturbed soil below the deepest soil penetrated by the drill bit by striking it with a 140 pound hammer dropped 30 inches. During a SPT sample, the number of blows to drive the sampler each 6 inches over an 18-inch interval was recorded and indicated on the boring log. The number of blows to drive the sampler the final 12 inches is termed the SPT resistance, or N-value, and is used to evaluate the strength and consistency/ relative density of the soil. The hammer used to perform SPT sampling was an automatic trip -release mechanism, which generally delivers a higher energy than a "standard" hammer equipped with a rope and cathead mechanism. The efficiency of the hammer mechanism is considered when evaluating the liquefaction potential of a soil. The SPT N-values reported on the borehole logs are field values, and are therefore not corrected for hammer efficiency, overburden stress or rod lengths. Soils samples were identified and described in general accordance with the guidelines shown on Figure A-1. Summary boring logs are included as Figures A-2 and A-3. The stratigraphic contacts shown on the summary logs and subsurface profiles (Figures 3 through 7, main text) represent the approximate boundaries between soil types; actual stratigraphic contacts encountered at other locations in the field may differ from the contact elevations shown on the logs, and may be gradual rather than abrupt. The soil and groundwater conditions depicted are only for the specific date and locations reported, and therefore, are not necessarily representative of other locations and times. 15-046 DBWH Geotechnical Study_final.docx A-2 PanGEO, Inc. RELATIVE U�NSITY / CONSISTENCY SAND I GRAVEL SILT 1 CLAY SPT Approx. Relative SPT Approx. Undrained Shear Dens' = N-values Density (/°) Consistent y N-values Strength (psf) Very Loose <4 <15 Very Soft <2 <250 Loose 4 to 10 15 - 35 Soft 2 to 4 250 - 500 Med. Dense 10 to 30 35 - 65 Med. Stiff 4 to 8 500.1000 Dense 30 to 50 65.85 Stiff 8 to 15 1000 - 2000 Very Dense >50 85.100 Very Stiff 15 to 30 2000 - 4000 Hard >30 >4000 It imirim Sm i CI ASSIFICATION SYSTEM MAJOR DIVISIONS GROUP DESCRIPTIONS •� GW: Well -graded GRAVEL Gravel GRAVEL (4%fines) ■ • •� .....:................................................... : GP Poorly -graded GRAVEL 50% or more of the coarse fraction retained on the $4 ; symbols sieve. Use dual symbols leg. Use dual GM : Silty GRAVEL GP -GM) °k fines. GRAVEL (>12%fines) ....... GC : Clayey GRAVEL ............................................................ :::: .............................................................. SW Weil•graded SAND ( ° ) $and SAND <5 /° fines ...............I ... I ............ ...................... 501° a mare of the coarse x SP : Poorly -graded SAND .....:...................................................... ......................... fradian passing the e4 sieve. 5M Silly SAND Use dual symbols (' SPsrA) SAND (>12%fines) for 5%!012% f nes : SC Clayey SAND ............ ...--... ................. MIL: SILT Liquid Limit < 50 CL : Lean CLAY Sift and Clay = — OL Organic SILT or CLAY' 50%or more passing #200 sieve n . + M Elastic SILT Liquid Limit > 50 . ...................................................... CH : Fat CLAY ...................................................... ON : Organic SILT or CLAY ... �, ..................................................................... Highly Organic Soils ..... M................................................... PT : PEAT Notes: 1 • $oil exploration togs contain matenal descriptions based an visual observation and field tests using a system modified from the Unillorm Soil Ctassification System (USCS). Where necessary taboratory tests have been conducted (as noted in [he 'Other Tests column), unit descnptions may include a dassification. Please refer to the discussions in the report text for a more complete description of the subsurface conditions. 2. The graphic symbols given above are not inclusive of all symbols that may appear on the borehole logs. Other symbols may be used where field observations indicated mixed soil constituents or dual constituent materials. DESCRIPTIONS OF SOIL STRUCTURES Layered: Units of material distinguished by color and/or composition from material units above and below Laminated: Layers of soil typically 0.05 to 1 mm thick, max.1 cm Lens: Layer of soil that pinches out laterally Intedayered: Altemating layers of differing soil material Pocket: Erratic, discontinuous deposit of limited extent Homogeneous: Soil with uniform color and composition throughout Fissured: Breaks along defined planes Slickensided: Fracture planes that are polished or glossy Blocky: Angular soil lumps that resist breakdown Disrupted: Soil that is broken and mixed Scattered: Less than one per foot Numerous: More than one per foot BCN: Angle between bedding plane and a plane normal to core axis COMPONENT DEFINITIONS COMPONENT SIZE / SIEVE RANGE COMPONENT SIZE / SIEVE RANGE Boulder. = > 12 inches Sand Cobbles: 3 to 12 inches Coarse Sand: #4 to #10 sieve (4.5 to 2.0 mm) Gravel Medium Sand: #10 to #40 sieve (2.0 to 0.42 mm) Coarse Gravel: = 3 to 314 inches Fine Sand: #40 to #200 sieve (0.42 to 0.074 mm) Fine Gravel: 3/4 inches to #4 sieve Silt 0.074 to 0.002 mm Clay = <0.002 mm U11"4.•LL �GE0 Terms and Symbols for r M C D R P o R A T E D Boring and Test Pit Logs TEST SYMBOLS for In Situ and Laboratory Tests listed in'�dther Tests" column. ATT AtterbergLimit Test Comp Compaction Tests Con Consolidation DD Dry Density DS Direct Shear %F Fines Content GS Grain Size Perm Permeability PP Pocket Penetrometer R R-value SG Specific Gravity TV Torvane TXC Triaxial Compression UCC Unconfined Compression SYMBOLS SampleM Situ test types and intervals 2-inch OD Split Spoon, SPT E (140-lb. hammer, 30" drop) OD Spilt Spoon H3.25-inch (3004 hammer, 30" drop) Non-standard penetration test (see boring log for details) Thin wall (Shelby) tube a Grab nRock core MVane Shear MONITORING WELL SZ Groundwater Level at time of drilling (ATD) 1 Static Groundwater Level Cement I Concrete Seal Bentonite grout / seal • 17 Silica sand backfill Slotted tip Slough Bottom of Boring MOISTURE CONTENT Dry Dusty, dry to the touch Moist Damp but no visible water Wet Visible free water Figure A 1 Project: Dumas Bay Landslide Assessment Surface Elevation: 95.0ft Job Number: 15-046 Top of Casing Elev.: 95.0ft Location: SW 307th Street, Federal Way, WA Drilling Method: Mud Rotary Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A z Q 'c rn Cn PL Moisture LL r 0 .' 0) E c d L .n E MATERIAL DESCRIPTION C 0 E a E N Cn 3 Lin E] Recovery Y U m O D 50 100 0 Dense, brown, silty, fine to medium SAND with gravel: moist, non -plastic, massive. (Till). 5 Dense, brown, poorly graded, fine to medium SAND with silt (SP-SM): moist, gravel beds, homogenous, laminated to massive. (Advanced Outwash). 10 9 S-1 X21 GS 23 15 S-2 35 50/5 Gravelly drilling, very dense. 20 27 Very dense, brown to gray, fine SAND with silt, moist, S-3 X 46 39 non -plastic, laminated to massive. Very dense, brown gray, sandy, fine GRAVEL: very moist, trace silt, rounded, blocky gravel, slightly weathered. 25 S 4 34 OD (Outwash). :aa 50/6 n ° o �D 30 18 o Losing drilling fluid into formation. Grading to fine to coarse S-5 33 41 o Q° GRAVEL with sand, massive. �D Qo Drilling mud color becomes gray. 35 o D Gravelly drilling stops at 36 feet. Hard, brown, silty SAND (SM): moist, slightly plastic fines, slow dilatancy, gray fine silt intedaminae, dips to 15°, _ homogeneous, laminated. (Outwash Beds). Completion Depth: 101.0ft Remarks: Groundwater measured 4/1/15. Date Borehole Started: 3/24/15 Date Borehole Completed: 3/25/15 Logged By: S. Evans Drilling Company: Holocene Drilling FbnGE@) LOG OF TEST BORING B-1 INCORPORATED FigureA-2 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 1 OT i Project: Dumas Bay Landslide Assessment Surface Elevation: 95.0ft Job Number: 15-046 Top of Casing Elev.: 95.Oft Location: SW 307th Street, Federal Way, WA Drilling Method: Mud Rotary Coordinates: Northing: , Easting: Sampling Method: SPT N-Value ) PL Moisture LL E E MATERIAL DESCRIPTION CL E F 3 91 Recovery U to m O 0 50 100 Hard, brawn, silty SAND {SM): moist, slightly plastic fines, 40 16 slow dilatancy, gray fine silt intedaminae, dips to 15°, S-6 X17 GS homogeneous, laminated. (Outwash Beds). (Continued) 23 45 Dense Gravel, very moist. (Outwash). 50 15 ° Q0 s-7 1s zo ao ° ❑a o D Fine gravel cuttings, 50 to 55 feet. o - 55 o� D ° ❑° Some fine gravel. _ _ _ _ _ _ Dense to very dense, brown, silty, fine SAND (SM): very moist, non -plastic fines, laminated with dips to 50, clayey silt 60 16 and gravelly interbeds. (Outwash). S-8 19 22 65 Gravel bed 65-66 feet. Some gravel 66 to 70 feet. 70 15 Clayey SILT bed. S-9 18 23 75 Completion Depth: 101.0ft Remarks: Groundwater measured 4/1/15. Date Borehole Started: 3/24/15 Date Borehole Completed: 3/25/15 Logged By: S. Evans Drilling Company: Holocene Drilling RnGEO LOG OF TEST BORING B-1 IN coRP0RAT00 FigureA-2 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 2 Of 3 Project: Dumas Bay Landslide Assessment Surface Elevation: 95.Oft Job Number: 15-046 Top of Casing Elev.: 95.0ft Location: SW 307th Street, Federal Way, WA Drilling Method: Mud Rotary Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A Z (n U o PL Moisture LL .' a ; MATERIAL DESCRIPTION c ® RQD Recovery M m O 0 50 100 Dense to very dense, brown, silty, fine SAND (SM): very moist, non -plastic fines, laminated with dips to 50, clayey silt 80 - 25 and gravelly interbeds. (Outwash). (Continued) S-10 34 GS Silty, fine SAND, moist, non -plastic, laminated, 36 sub -horizontal laminae. Gravelly bed 83 to 86 feet. 85 Very dense, brown SILT with fine sand: very moist, non -plastic, rapid dilatancy, homogenous, laminated with 903s rusty laminae, dips 3 to 100. (Outwash). S-11 50/5 ' 95 100 S-12 30 50/6 Bottom of Boring. 1D5 110 115 Completion Depth: 101.0ft Remarks: Groundwater measured 4/1115. Date Borehole Started: 3/24/15 Date Borehole Completed: 3/25/15 Logged By: S. Evans Drilling Company: Holocene Drilling PmGE& LOG OF TEST BORING B-1 I N C O R P O R A T E D Figure A-2 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 3 OT i Project: Dumas Bay Landslide Assessment Surface Elevation: 141.Oft Job Number: 15-046 Top of Casing Elev.: 141.0ft Location: SW 307th Street, Federal Way, WA Drilling Method: Mud Rotary Coordinates: Northing: , Easting: Sampling Method: SPT N-Value Z o - co Cn o PL Moisture LL .' aa) a ; E MATERIAL DESCRIPTION 0 c N 0 O ® RQD Recovery Fn 0 50 100 0 Planter Backfill, mixed sand, gravel, silt and organics. (Fill). 5 Dense, brown, silty, fine SAND (SM): moist,slightly plastic, some gravel, massive with occasional fine rusty mottles. (Till). 10 11 S-1 13 GS 18 15 20 11 Light brown, fine sandy SILT, some gravel, massive. S-2 17 17 Some gravelly drilling at 22 feet. 25 30 is Grading to silty, fine to medium SAND with fine, rounded S-3 X 18 18 gravel, moist, massive. Gravelly drilling 31 to 35 feet. 35 Medium dense, brown, silty, fine SAND: moist with very moist interbeds, non -plastic, finer/coarser beds, laminated. (Outwash). Completion Depth: 140.5ft S Remarks: Groundwater measured 4/1/15. Date Borehole Started: 3/26/15 + Date Borehole Completed: 3/30/15 Logged By: S. Evans Drilling Company: Holocene Drilling RmGEO LOG OF TEST BORING B-2 �NC09P0RAT9D FigureA-3 The stratification lines represent approximate boundaries. The transition may be gradual. ,sheet l OT 4 Project: Dumas Bay Landslide Assessment Job Number: 15-046 Location: SW 307th Street, Federal Way, WA Coordinates: Northing: , Easting: .� o Z a In c n n o E 0 � m O Surface Elevation: 141.0ft Top of Casing Elev.: 141.0ft Drilling Method: Mud Rotary Sampling Method: SPT MATERIAL DESCRIPTION Medium dense, brown, silty, fine SAND: moist with very 40 12 moist interbeds, non -plastic, finer/coarser beds, laminated. S-4 9 (Outwash). (Continued) 12 45 Dense, brown, silty, flue to medium SAND (SM): very moist, 1 silty interbeds and laminae, occasional rusty bands, laminated, dips to 5°. (Outwash). 50 t3 S-516 55 60 22 Very dense, brown, flne to medium SAND, very moist, S-6 33 GS 40 massive, with pockets of silt. :'- Trace gravel at 62 feet. ':1-;- _A Losing drilling fluid 62 to 65 feet. 65 70 19 Brown, fine to medium SAND, very moist to wet, massive.. S-7 X 22 28 75 Very dense, brown gray, silty, fine SAND: very moist, non -plastic, homogeneous, massive. (Outwash). Completion Depth: 140.5ft Remarks: Groundwater measured 411/15. Date Borehole Started: 3126/15 Date Borehole Completed: 3/30/15 Logged By: S. Evans Drilling Company: Holocene Drilling TAlCER LOG OF TEST BORING B-2 fN C 0 R P U R A T E D Figure A-3 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 2 Of 4 Project: Dumas Bay Landslide Assessment Surface Elevation: 141.Oft Job Number: 15-046 Top of Casing Elev.: 141.Oft Location: SW 307th Street, Federal Way, WA Drilling Method: Mud Rotary Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A z 0-C PL Moisture LL a L E MATERIAL DESCRIPTION cc y 0 O ® RQD Recovery 0 50 100 Very dense, brawn gray, silty, fine SAND: very moist, non -plastic, homogeneous, massive. (Outwash). 80 P6 (Continued) S-8 X 38 48 85 90 27 Brown gray, fine SAND with non -plastic silt, laminated, dips S-9 34 35 0 to 50. 95 Very dense, gray to brown SILT (ML): very moist with wet layers, non -plastic to slightly plastic, rapid dilatancy in some layers, laminated, some rusty weathering. (Outwash). 100 13 S-10 26 GS 33 -105 Very dense, light brown gray, fine SAND with silt: very moist, non -plastic, homogeneous, laminated. (Outwash). 110 S-11 35 5016 :may -' 115 ------------------------ 7 Completion Depth: 140.5ft Remarks: Groundwater measured 4/1/15. Date Borehole Started: 3/26/15 Date Borehole Completed: 3130/16 Logged By: S. Evans Drilling Company: Holocene Drilling PmGEO LOG OF TEST BORING B-2 I N C 0 R P 0 R A T e O FigureA-3 The stratification lines represent approximate boundaries. The transition may be gradual. 5neet ;i OT 4 Project: Dumas Bay Landslide Assessment Surface Elevation: 141.0ft Job Number: 15-046 Top of Casing Elev.: 141.0ft Location: SW 307th Street, Federal Way, WA Drilling Method: Mud Rotary Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A o Z a ci PL Moisture LL E a a Q N E MATERIAL DESCRIPTION _ 2 � E E 3 C 0 RQD RecoveryEl •J o to to m O 0 50 100 Very dense, light brown gray, fine sandy SILT (ML), very moist, non -plastic fines, laminated with occasional rusty laminae. (Outwash). (Continued) 120 27 S-12 X 35 GS 44 125 130 S-13 51 Rusty fine sand SILT, verymoist to wet, non -plastic, 5o/a rapid dilatancy, one rounded pocet of low plastic, gray, clayey silt. 135 140 S-14 50/6 Fine sandy SILT, homogeneous, massive, non -plastic. Bottom of Boring. 145 150 155 Completion Depth: 140.5ft Remarks: Groundwater measured 4/1115. Date Borehole Started: 3/26/15 Date Borehole Completed: 3/30115 Logged By: S. Evans Drilling Company: Holocene Drilling PmGE(9 LOG OF TEST BORING B-2 I N C O R P Q R A T V v Figure A-3 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 4 OT 4 APPENDIX B LABORATORY TESTING Dumas Bay West September 16, 2015 LABORATORY TESTING This appendix contains descriptions of the procedures and results of physical (geotechnical) laboratory testing conducted on soil samples recovered during the field exploration program. The selected samples were tested to determine basic physical index properties of the soils for purposes of classifying the material types encountered and to measure or correlate parameters used in the geotechnical design. The laboratory tests were performed in general accordance with the following ASTM Standard Test Methods: D2216 — Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock D422 — Standard Test Method for Particle -Size Analysis of Soils D1140 — Standard Test Method for Percentage of Material Finer than #200 Sieve Moisture contents and percent finer than #200 Sieve (where determined) are shown on the summary boring logs. The results of particle -size analyses (grain size distribution) are presented on Figure B-1. 15-046 DBWH Geotechnical Study_final.docx B-1 PanGEO, Inc. F 90 80 70 2 (2 60 w co m of Z 50 w H z w W 40 w a 30 20 10 0 U.S. SIEVE OPENING IN ft,,IES I U.S. SIEVE NUMBERS I HYDROMETER ' :11J1J1r.II1LJ11r..40 us ., , si��a�a■■�■rr�u��r��ee��►\E+st•e��11B■■■�� yll■■■�� 100 10 1 U.1 GRAIN SIZE IN MILLIMETERS U.0 I 0.001 1 COBBLES GRAVEL coarse fine SAND SILT OR CLAY coarse medium fine Specimen Identification Classification LL PL PI Cc Cu • B-1 @ 10.0 ft. Poorly graded SAND with silt (SP-SM) 1.62 3.95 m B-1 @ 40.0 ft. silty SAND (SM) A >n B-1 @ 80.0 ft. silty SAND (SM) * &2 @ 10.0 ft. silty SAND (SM) O &2 @ 60.0 ft. silty SAND (SM) W Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt %Clay Q r &1 10.0 9.5 0.304 0.194 0.077 0.1 90.2 9.7 Q m &1 40.0 0.075 0.0 0.0 46.9 A &1 80.0 1 9.5 0.214 0.089 0.0 74.3 25.6 Y * &2 10.0 19 0.18 4.8 54.1 41.1 a ( &2 60.0 4.75 0.183 0.093 1 0.0 76.2 23.8 GRAIN SIZE DISTRIBUTION $ PmGEO Project: Dumas Bay West Figure 'W-� , N C O R P O R A T E o Job Number: 15-046 B-1 .3 Phone: 206.262.0370 Location: SW 307th Street, Federal Way, WA r� c� Specimen Identification D100 D60 D30 D10 %Gravel %Sand %Silt I %CI B-2 100.0 0.075 0.0 0.0 88.1 B-2 120.0 2 0.0 33.3 66.7 GRAIN SIZE DISTRIBUTION PanGEOProject: Dumas Bay West Figure 1 N C o R P O R A T E D Job Number: 15-046 B-2 Phone: 206.262.0370 Location: SW 307th Street, Federal Way, WA September 2, 2015 Carl F Jonasson 4346 SW 307`h Street Federal Way, WA 98023 Email: carl.jonasson@comcast.net �`�w.sarr Jim Ferrell, Mayor FILE RE: File #15-103940-00-SH; GEOTECHNICAL CONSULTANT REVIEW Dumas Bay West, 4346, 4342, 4338 SW 307th Street and 30625 43"' Ave SW, Federal Way Dear Mr. Jonasson: Arnec Foster Wheeler (Amec), the City's geotechnical consultant, has reviewed your July 16, 2015, Geotechnical Engineering Study and Recommendations, prepared by PanGEO, in addition to the Slope Remediation Plans, dated June 2015, prepared by CT Engineering Inc., and Erosion Control, Grading, Access, Staging Plans prepared by Jonasson Consultants, LLC, for the development of the proposed soldier pile and tieback retaining wall. Amec's initial review has been completed. Enclosed please find the September 1, 2015, review comments from Amec. Based on the review of the submitted information and review of the Federal Way Revised Code (FWRC), Amec has identified specific issues and requirements that must be addressed prior to approval of the project. Please have PanGEO revise the report to address the comments made by Amec. When resubmitting, please provide three 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, Becky C in Associat Planner enc: Resubmittal Information Form Amec Foster Wheeler Review Comments, dated September 1, 2015 Doc I D 70482 33325 8th Avenue South, Federal Way, WA 98003-6325 (253) 835-7000 www.cityoffederalway.com September 1, 2015 Project No. 5-917-17902-0 City of Federal Way Community Development Department 33325 8th Avenue South Federal Way, Washington 98003 Attention: Ms. Becky Chapin, Associate Planner Subject: Geotechnical Review of Documents Dumas Bay West Coastal Bluff Repair SW 307th Street & 431d Avenue SW Federal Way, Washington File No. 15-103940-00-SH Dear Becky: 1. amen foster wheeler This letter presents the results of our third -party review of geotechnical engineering reports and related documents for the proposed Dumas Bay West coastal bluff stability improvements. At your request, we reviewed the following documents: • Geotechnical Engineering Study (dated July 16, 2015) prepared by PanGEO; ■ Geotechnical Engineering Recommendations 4346 SW 307th Street (dated July 17,2015) prepared by PanGEO; • Geotechnical Engineering Recommendations 30625 43rd Avenue SW (dated July 17,2015) prepared by PanGEO; • Geotechnical Engineering Recommendations 4338 SW 307th Street (dated July 17,2015) prepared by PanGEO; • Geotechnical Engineering Recommendations 4342 SW 307th Street (dated July 17,2015) prepared by PanGEO; • Slope Remediation Plans for Ansari, Donovan, Jonasson, and Reagan Properties (dated June 2015) prepared by CT Engineering Inc.; and • Erosion Control, Grading, Access, Staging Plans prepared by Jonasson Consultants, LLC. 11810 North Creek Parkway N Bothell, Washington 98011 (425) 368-1000 Phone www.amecfw.com W:\_Projects\17000s\17902 City of Federal Way\Dumas Bay West Landslide Repair Review 150901 docx Our review tasks were: 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. 2. Discuss the proposed compliance with FWRC 15.05.040(1), Impact mitigation. 3. Provide a memorandum identifying additional information requested as necessary. 4. Conduct site visit as necessary. 5. Provide written response as to whether or not we concur with PanGEO's recommended actions. SITE AND PROJECT DESCRIPTION A large landslide occurred on the coastal bluff at 4342 SW 307th Street on January 18, 2015. The slide extended from the backyard of the residence at the top of the bluff, down to the beach, an elevation change of over 100 feet. The landslide mass was estimated to be around 20 feet thick normal to the slope. About 10 feet of the backyard was lost at the top of the landslide, leaving a very steep main scarp that is near vertical. The lower portion of the landslide is sloped at 70% to 90%, and the undisturbed areas are sloped at approximately 100%. The time of the landslide coincided with very high tides and a storm with high north winds. Wave action eroding the toe of the slope probably triggered the landslide. Also, there was a significant amount of rainfall in the preceding 2 weeks that may have raised groundwater levels and saturated the surficial soils. The coastal bluff consists of a thin capping layer of Vashon Glacial Till, over a thick layer of Vashon Advance Outwash silty sands. No significant signs of groundwater seeps have been observed on the slope. The groundwater table may be near beach elevation at the toe of the slope. As a result of this landslide and previous landslides on adjacent properties, a group of homeowners formed the Dumas Bay West Homeowners, LLC and hired PanGEO to investigate the slope conditions and recommend stability improvements to protect their homes. Using the results of that study and structural engineering by CT Engineering, they are applying for a permit to construct a soldier pile and tieback retaining wall along the top of the slope of four parcels: 4346, 4342, 4338 SW 307th Street, and 30625 43rd Avenue SW. We were given a tour of the four parcels by Carl Jonasson on August 25, 2015. We looked at the top of the bluff from each of the four parcels and also walked along the beach to observe the toe of the slope. Photographs were taken for our files. We noted that the site conditions had been accurately described in PanGEO's report. REVIEW COMMENTS We found the reports and plans to be thorough and technically sound. The studies and proposed repair plans meet the requirements of FWRC 15.10.160 and FWRC 15.05.040. We agree with most of the conclusions, recommendations, and engineering, and have only a few comments that we ask the engineers and applicants to consider. Our review and comments have been based on the City of Federal Way critical area regulations and typical/standard engineering geology and geotechnical engineering practices regarding Puget Sound coastal bluffs. The global stability results discussed in the Geotechnical Engineering Study dated July 16, 2015, for Section B and presented in Figure 6 should be explained in more detail. The model represents undisturbed soils, and therefore represents the stability at some setback distance from the scarp, similar to Figure 4. However, the safety factor would be lower for a potential slip surface that started from the observed tension cracks and continued through the slide debris because the tension crack and the slide debris would not have any cohesive strength. 2. The recent landslide on the Regan parcel has left a near vertical main scarp and other tension cracks in the backyard of the residence. For safety purposes, PanGEO could recommend a minimum distance that residents should stay back from the bluff edge in the interim, until the retaining wall is constructed. 3. The lateral earth pressure diagrams provide recommendations for surcharges at the top of the retaining wall, but the text of the report states that there will not be any surcharges. An explanation for the surcharge recommendations should be provided, or the surcharge could be removed from the diagrams. 4. The geotechnical engineering recommendations for 4342 SW 307th Street and 30625 431 Avenue SW state that wall backfill will be placed. Recommendations for the type of backfill and placement methods should be provided by PanGEO. We recommend that PanGEO review and approve the contractor's submittal for the "construction sequence narrative and description including equipment list and key personnel," as stated on the Structural Notes SS1.0, 00603, to verify that the contractor's approach does not adversely affect site stability during construction. 6. We recommend PanGEO be on site during construction to monitor slope stability conditions and confirm construction activities do not adversely affect site stability. 7. An as -built survey of the retaining wall should be required since this will provide baseline data for monitoring any long-term movement of the wall. 8. We understand the goal is to avoid disturbing the slope on the downhill side of the soldier pile retaining wail. However, it is likely some soils will fall on the slope during drilling of soldier pile holes, and localized slope disturbance will occur by foot traffic for guiding soldier piles, and installing lagging and tiebacks. Therefore, the project plans should include erosion control requirements for the solider pile wall construction area, for both during and after construction, similar to what is shown on plan sheets G1.0 and G2.0 for the access routes. CLOSURE We appreciate the opportunity to be of service. It should be noted that our scope of work for this third party review was limited to a review of the documents supplied to us and a visit to the site. Our scope did not include subsurface exploration or engineering analyses, nor does our review purport to verify the accuracy of the geotechnical engineering results presented within the documents. If you have any questions, please contact us at your convenience. Sincerely, Amec Foster Wheeler Environment & Infrastructure, Inc. Todd D. Wentworth, P.E., L.G. Senior Associate Geotechnical Engineer amec foster wheeler Project: 5917179020 -- On -Call Third Party Geotech Review Phase: 002 -- Dumas Bay West Landslide File #15-103940-00-SH Task: Fees Reg/OT Class / Employee Name Ind 130 - Associate/ Project Manager Wentworth,Todd D R Total : Associate/ Project Manager 170 - Clerical/ Admin Fitzgerald, Crystal Leanne R Total: Clerical/ Admin Total Fees Reimbursable Expenses Vendor Name Auto/Mileage Wentworth,Todd D Total: Auto/Mileage Total Reimbursable Expenses Total Expenses Total Task: Total Phase : 002 -- Dumas Bay West Landslide Hours 0.40 0.40 3.40 Cost 40.25 Total Project: 5917179020 -- On -Call Third Party Geotech Review Invoice # : S25751260 Rate Amount 160.0000 480.00 480.00 70.0000 28.00 28.00 508.00 Multiplier Amount 1.1500 46.29 46.29 46.29 46.29 554.29 Fees 508.00 Expenses 46.29 Total 554.29 554.29 Page: 2 amec ester wheeler Project : 5917179020 -- On -Call Third Party Geotech Review Invoice # : S25751178 Phase: 002 -- Dumas Bay West Landslide File #15-103940-00-SH Task: Fees Reg/OT Class/Employee Name Ind Hours Rate Amount 100 - Principal/ Senior Review Dransfield,James S R 1.00 195.0000 195.00 Total : Principal/ Senior Review 1.00 195.00 130 - Associate/ Project Manager Wentworth,Todd D R 15.70 160.0000 2,512.00 Total : Associate/ Project Manager 15.70 2,512.00 170 - Clerical/ Admin Fitzgerald, Crystal Leanne R 0.40 70.0000 28.00 Hansen,Amy M R 1.10 70.0000 77.00 Stonehouse,James L R 1.50 70.0000 105.00 Total: Clerical/ Admin 3.00 210.00 Total Fees 19.70 2,917.00 Total Task: **** - **** 2,917.00 Total Phase : 002 -- Dumas Bay West Landslide Fees 2,917.00 Expenses 0.00 Total 2,917.00 Total Project: 5917179020 -- On -Call Third Party Geotech Review 2,917.00 Page: 2 FILE August 14, 2015 Jim Ferrell, Mayor Carl F. Jonasson 4346 SW 3071h Street Federal Way, WA 98023 RE: File #15-103940-00-SH; CONSULTANT REVIEW ESTIMATE Dumas Bay West Homeowners, *No Site Address*, Federal Way Dear Mr. Jonasson: Please find the enclosed Geotechnical Consultant Task Authorization form provided by the City and Amec Foster Wheeler (Amec) for review of the submitted Geotechnical Engineering Study and Recommendations, prepared by PanGEO Inc. The normal course of action for the City is to set up an account to be funded by the applicant and drawn down by the work performed by Amec. Please note: any funds that are not used will be returned to you. At this point, please review the proposed work description. If you agree with the cost estimate, payment in the amount of $4,000.00 (check moist be payable to the City of Federal Way) and your signature on the City's `Geotechnical Consultant Authorization Form' must be submitted before the review will commence. Following receipt, I will authorize Amec to begin their formal review. If you have any questions regarding this letter or your project, please contact me at 253-835-2641 or Becky.chapin@cityoffederalway.com. Sincerely, B"Cha Nor-;�� Associate Planner enc: Geotechnical Consultant Authorization Form City of Federal Way Invoice Doc. I D. 70478 33325 8th Avenue South, Federal Way, WA 98003-6325 (253) 835-7000 www.cityoffederalway.com jet% CITY OF well Federal Way GEOTECHNICAL CONSULTANT AUTHORIZATION FORM Date: August 12, 2015 City: City of Federal Way Community Development Department 33325 8th Avenue South Federal Way, WA 98003 Consultant: Todd Wentworth, Geotechnical Engineer Amec Foster Wheeler 11810 North Creek Parkway North Bothell, WA 98011 T:425-368-0937 Project: Dumas Bay West Homeowners 4342, 4338, 4346 SW 307[h Street & 30625 43`d Avenue SW Parcel #112103-9071, 112103-9031, 112103-9030, and 112103-9088 File No.: 15-103940-00-SH (Shoreline Substantial Development Exemption Permit) Project Proponent: Carl Jonasson 4346 SW 307`h Street Federal Way, WA 98023 253-963-1718 Project Proponent PanGEO Geotechnical Robert E. Kimmerling Consultant: Principal Geotechnical Engineer 3213 Eastlake Avenue East, Suite B Seattle, WA 98102 206-262-0370 Project Planner: Becky Chapin, Associate Planner becky.ch apin @citkoffederalway.com 253-835-2641 Project Background: The applicant has submitted geotechnical reports to address and evaluate the stability of a coastal bluff located along several properties along Puget Sound. There were recent landslides on the subject lots and the proposed recommendations include 24" diameter soldier piles, 50-60 feet deep. Engineered plans have also been included. Documents a Geotechnical Engineering Study (dated July 16, 2015) prepared by PanGEO Provided: R Geotechnical Engineering Recommendations 4346 SW 3071h Street (dated July 17, 2015) prepared by PanGEO 0 Geotechnical Engineering Recommendations 30625 43rd Avenue SW (dated July 17, 2015) prepared by PanGEO O Geotechnical Engineering Recommendations 4338 SW 307`" Street (dated July 17, 20.15) prepared by PanGEO F Geotechnical Engineering Recommendations 4342 SW 307`" Street (dated July 17, 2015) prepared by PanGEO • Slope Remediation Plans for Ansari. Donovan, Jonasson, and Reagan Properties (dated June 2015) prepared by CT Engineering Inc. A Erosion Control, Grading, Access, Staging Plans prepared by Jonasson Consultants LLC Task Scope: 1. Review submitted documents for con€ormance to Federal -Way Revised Corse (FWRC) Chapter 15.10, Critical Areas, especially FWRC 15.10.160 and FWRC 15.05.040(4)(b) Geologically Hazardous Areas. 2. Discuss the proposed compliance with FWRC 15,05.040(1), Impact mitigation. 3. Provide a memorandum identifying additions information re uested as necessary. 4. Conduct site visit as necessary. .Twdu•1-,A *`4 5. Provide written response as to whether or not Amec Foste>Wlieeler concurs with PanGEO's recommended actions. Task Cost: Not to exceed $ '-06 (? without a prior written amendment to this Task Authorization. Acceptance: 4 City of Federal Way ,(Planner) Elate Consultant,:.n.a foster Wheeler) e-:7- Project (Carl Jonasson) rwoterhnic:al Consultant Authorization Form (r Dme Date CITY OF FEDERAL WAY COMMUNITY DEVELOPMENT DEPARTMENT DEVELOPMENT REVIEW COMMITTEE TRANSMITTAL DATE: August 12, 2015 TO: E.J. Walsh, Development Services Manager Peter Lawrence, Plans Examiner Brian Asbury, Lakehaven Utility District Chris Ingham, South King Fire & Rescue FROM: Becky Chapin, Associate Planner FOR DRC MTG. ON: Please email comments. FILE NUMBER(s): 15-103940-SH RELATED FILE NOS.: 15-101159-PC PROJECT NAME: Dumas Bay West Retaining Wall PROJECT ADDRESS: 4346, 4342, 4338 SW 307th ST & 30625 43rd Ave SW ZONING DISTRICT: SE PROJECT DESCRIPTION: Shoreline exemption request to construct new rock bulkhead. 24" diameter soldier piles, 60 feet deep on 6 foot centers, no lagging or tie -backs. LAND USE PERMITS: Shoreline Substantial Development Permit Exemption PROJECT CONTACT: Carl Jonasson 4346 SW 307" ST Federal Way, WA 98023 MATERIALS SUBMITTED: • Shoreline Substantial Development Permit Exemption Application • Geotechnical Report for Jonasson, Reagan, Ansari, Donovan Properties • Drawing set for each property • Erosion Control, Grading, Access, Staging Plan rAj LO 0 0 N 6� A ABBREVIATIONS ABBREVIATIONS 00100- CODE REQUIREMENTS 00600- MATERIALS 08000-TIEBACK INSTALLATION 01000 - NOTES ABOUT TIEBACK SEQUENCING & AND I.F. INSIDE FACE ALL DESIGN AND CONSTRUCTION SHALL CONFORM TO THE 2012 INTERNATIONAL BUILDING CODE, LEAN MIX CONCRETE 1 112 SACK MIX CASING OR AUGERCAST METHOD SHALL BE USED FOR PRIMARY GROUTING OF TIEBACK ANCHORS TIEBACK INSTALLATION IS REQUIRED AT THE INITIAL INSTALLATION OF PILES ON THIS @ AT IN. INCH(ES) AS AMENDED BY THE CITY OF SEATTLE, WASHINGTON. TO MINIMIZE GROUND LOSS SHOULD CAVING SOIL CONDITIONS BE ENCOUNTERED. HOLES PROPERTY. SEE ELEVATIONS AND SCHEDULES FOR DETAALS. FUTURE INSTALLATION OF FEET (FOOT) INFO. INFORMATION ALL PILES, GROUT AND TIMBER LAGGING WITHIN THE CITY RIGHT-OF-WAY SHALL BE REMOVED TO DRILLED FOR TIEBACKS SHALL BE GROUTED/FILLED PROMPTLY TO REDUCE THE POTENTIAL FOR TIEBACKS MAY BE NECESSARY IF SLOUGHING OR UNRAVELLING OF THE SLOPE OCCURS. AT " INCH (INCHES) INT. INTERIOR A DEPTH OF 4 FEET BELOW THE FINISH GRADE AFTER THE SHORING IS NO LONGER REQUIRED FOR STRUCTURAL GROUT f'c = 3000 PSI (@ 5 DAYS), 9 SACK LOSS OF GROUND. SUCH TIME, TIEBACKS SHALL BE INSTALLED PER THE SEQUENCING DETAILS GIVEN IN DETAIL POUND(S), NUMBER EXCAVATION STABILITY. MIN. 8/SS4'THIS SET. # EQUAL(S) JST. JOIST THE GEOTECHNICAL ENGINEER WILL OBSERVE ALL TIEBACK HOLES AND APPROVE THEM PRIOR PUMPABLE, 8" MINIMUM SLUMP TO TIEBACK AND GROUT INSTALLATION. DO NOT FORCE THE TIEBACK INTO THE HOLE. LOOSE CT ENGINEERING INC SHOULD BE RETAINED AT THAT TIME TO ASSESS THE EXTENT OF SOIL JT. JOINT 00101- EASEMENTS SOIL AND SLOUGH SHALL BE REMOVED FROM THE HOLES DRILLED FOR TIEBACK ANCHORS PRIOR MOVEMENT RELATIVE TO THE DESIGN CASE, AND PROVIDE ADDITIONAL SITE -SPECIFIC A.B. ANCHOR BOLT TO INSTALLING THE TIEBACK. DETAILS REGARDING ADDITIONAL TIEBACK INSTALLATION AND WALER DESIGN AS MAY BE ABV. ABOVE K KIPS (1000 LB.) ALL EASEMENTS SHALL BE THE RESPONSIBILITY OF THE OWNER. STRUCTURAL STEEL WF SECTIONS ASTM A992 Fy - 50 KSI REQUIRED. SHOULD ADDITIONAL TIEBACK INSTALLATION BE REQUIRED, THEN SWIFT ACTION ADD. ADDITIONAL TIEBACK ANCHORS SHALL ONLY HAVE THE BOND ZONE FILLED WITH STRUCTURAL GROUT. SHALL BE TAKEN TO ENSURE THAT THESE ARE INSTALLED TO AVOID CONDITIONS WHERE ADJ. ADJACENT EAT. LATERAL OOZOO- DESIGN -LOADS &CONSIDERATIONS CHANNELS ASTM A36 Fy = 36 KSI NO-LOAD ZONES SHALL BE IMMEDIATELY BACKFILLED WITH LEAN MIX CONCRETE TO PREVENT THE WALL LOADS MAY BECOME GREATER THAN THE DESIGN CASE. ALUM. ALUMINUM LB. POUND(S) STEEL ANGLES ASTM A36 Fy = 36 KSI CAVING OF THE BORE HOLE. ALT. ALTERNATE L.B. LAG BOLTS(S) DESIGN LOADS FOR THE SHORING SYSTEM AREAS SPECIFIED IN INC. REPORT 15 PLATE MATERIAL ASTM A36 Fy = 36 KSI SPACERS SHALL BE USED ALONG THE TIEBACK TENDON BOND LENGTH TO SEPARATE EACH OF DANGEO,TIONS -04 DATED JULY 17, 2015 (GEOTECHNICAL ENGINEERING RECOMMENDATIONS} AND REPORT 15-046 APPROX. APPROXIMATELY) LG. LONG(ITUDlNAL) DATED JULY 09, 2015 (GEOTECHNICAL ENGINEERING STUDY) AND ARE AS INDICATED IN THE STRUCTURAL PIPE ASTM A53 Fy = 35 KSI GRADE B THE STRANDS SO THAT THEY WILL BOND TO THE GROUT. ARCH. ARCHITECT(URAL) LGTH. LENGTH DETAILS. STRUCTURAL BOLTS ASTM A 325-N CENTRALIZERS SHALL BE PROVIDED TO ALLOW THE GROUT TO FLOW FREELY AND PROVIDE A ASSY. ASSEMBLY LGMF. LLH LIGHT GAUGE METAL FRAMING LONG LEG HORIZONTAL THE SHORING SYSTEM IS PERMANENT. TIEBACKS WHERE NEEDED ARE PERMANENT. WELDED HEADED STUDS (WHS) ASTM A -108 MINIMUM OF 2 INCHES OF COVER OVER THE TENDON. B. (BTM.) BOTTOM LLV LONG LEG VERTICAL CONSTRUCTION CONSIDERATIONS: WELDING ELECTRODES E70-XX WITH CHARPY V-NOTCH TIEBACKS ARE PERMANENT AND ARE TO REMAIN TENSIONED PERMANENTLY. BEE. BELOW LSH LONG SLOTTED HOLE(S) - CARE SHOULD BE TAKEN DURING CONSTRUCTION TO NOT UNNECESSARILY PLACE LIVE LOAD TOUGHNESS OF AT LEAST 20 FT-LBS AT 0 DEGREES F. BEN BOUNDARY EDGE NAILING L.W. LIGHTWEIGHT SURCHARGES CLOSE TO THE CREST OF THE BLUFF AS THIS COULD RESULT IN LOCAL INSTABILITY. B.F. BRACED FRAME - UPON COMPLETION, GRADES BETWEEN THE RETAINING STRUCTURE AND THE RESIDENTIAL 00801- ANCHORS -PERFORMANCE TESTING BLDG. BUILDING MAT. MATERIAL STRUCTURE SHOULD BE RETURNED TO SIMILAR CONDITIONS AS BEFORE CONSTRUCTION SUCH TIMBER LAGGING P.T. HF NO. 2 4X6 THAT SURFACE WATER RUNOFF IS NOT DIRECTED OVER THE WALL AND INTO STEEP SLOPED BELOWEVERY BLK.(G.) BLOCK (ING) MAX. MAXIMUM THE COASTAL BLUFF. PRODUCTION TIEBACK SHALL BE TESTED USING THE PROOF TESTING PROTOCOL. AT BLW. BELOW M.B. MACHINE BOLT ANCHOR TENDONS .6 IN. DIA., 7-WIRE STRAND ASTM A416 LEAST ONE VERIFICATION TEST SHALL BE PERFORMED PRIOR TO THE INSTALL OF PRODUCTION BM. BEAM MBM METAL BUILDING LOW RELAXATION Fy = 270 KSIPu = 58.5 KIPS ANCHORS. BMU BRICK MASONRY UNIT MECH. MANUFACTURER MECHANICAL SPECIFIC RECOMMENDATIONS: - GEOTECHNICAL ENGINEER SHALL VERIFY THE SUITABILITY OF ALL SOLDIER PILE AND/OR TIEBACK TIMBER LAGGING SHALL BE PRESERVATIVE TREATED WITH WATER BORNE PRESERVATIVES IN 00901- PROOF TEST (150% TEST) BN BOUNDARY NAILING M.E.J. MASONRY EXPANSION JOINT HOLES BEFORE CONCRETE PLACEMENT. ACCORDANCE WITH AWPA U1 (A OR F) TO A MINIMUM RETENTION OF 0.4 LBS/CU. FT. (0.21 LBS/CU. BNDRY. BOUNDARY - TEMPORARY CASING SHOULD BE USED IF CAVING OCCURS AS DETERMINED BY THE FT. FOR CA-B) ANY SAWN ENDS OF SUCH TREATED LAGGING SHALL BE FIELD TREATED WITH TWO a 1. PROOF TEST SHALL BE PERFORMED ON EACH PRODUCTION ANCHOR TO 150 /o OF THE B.O. BOTTOM OF MEZZ. MEZZANINE GEOTECHNICAL ENGINEER. BRUSHED COATS OF THE SAME PRESERVATIVE. LAGGING SHALL BE GAPPED PER THE DESIGN LOAD. B.O.E. BOTTOM OF EXCAVATION MFR. MANUFACTURER - TREMIE METHODS SHALL BE USED FOR CONCRETE PLACEMENT IN ALL HOLES HAVING 3 OR MORE GEOTECHNICAL ENGINEER TO PERMIT SEEPAGE. 2. PROOF TESTS SHOULD NOT BE INITIATED UNTIL THE TIEBACK GROUT HAS ATTAINED AT B.O.F. BOTTOM OF FOOTING MIN. MINIMUM INCHES OF ACCUMULATED WATER. LEAST 50 PERCENT OF THE SPECIFIED 28-DAY COMPRESSIVE STRENGTH. misc. MISCELLANEOUS - ALL SOLDIER PILE HOLES SHALL BE DRILLED AND FILLED WITH CONCRETE ON THE SAME DAY. BRDG. BRIDGE, BRIDGING MTL. METAL - THE GEOTECHNICAL ENGINEER SHALL WINESS AND VALIDATE VERIFICATION AND PROOF TESTING DESIGN, FABRICATION AND ERECTION OF STRUCTURAL STEEL SHALL BE IN ACCORDANCE WITH 3. THE ANCHOR SHALL BE SEATED BY APPLYING AN ALIGNMENT LOAD. THE ALIGNMENT LOAD BRG. BEARING OF ANY TIEBACKS AND CONFIRM THAT TEST RESULTS MEET ACCEPTANCE CRITERIA. THE 14TH EDITION OF THE AISC "STEEL CONSTRUCTION MANUAL AND THE SPECIFICATION FOR SHALL BE BETWEEN 2% AND 10% OF THE DESIGN LOAD. THE LOAD SHALL THEN BE HELD AND BTWN. BETWEEN STRUCTURAL STEEL BUILDINGS", AISC 360-10. ZERO DEFLECTION READING TAKEN. N.L.B. NON -LOAD BEARING 00300-UTILITIES AND ADJACENT PROPERTIES 4. PROOF TESTS SHALL BE PERFORMED BY INCREMENTALLY LOADING THE ANCHOR IN C CAMBER NO. N.S. NUMBER NEAR SIDE STABILITY AND EROSION PROTECTION OF EXISTING &CUT SLOPES, AND THE COORDINATION OF ACCORDANCE WITH THE SCHEDULE BELOW. THE ANCHOR MOVEMENT SHALL BE MEASURED, CAMB. CAMBERED) THE EXCAVATION, SHORING AND OTHER WORK WITH ALL UTILITIES AND ADJACENT PROPERTIES IS 00601-CORROSION PROTECTION RECORDED TO THE NEAREST 0.01 INCH WITH RESPECT TO AN INDEPENDENT FIXED CANT. CANTILEVERED) N.T.S. NOT TO SCALE THE RESPONSIBILTY OF THE CONTRACTOR PRIOR TO DRILLING AND EXCAVATION. REFERENCE POINT IN THE SAME MANNER AS FOR THE VERIFICATION TESTS AT THE CF CUBIC FOOT N.W.C. NORMAL WEIGHT CONCRETE THE PILES AND TIEBACK ANCHORS FOR THIS PROJECT ARE PERMANENT AND DO REQUIRE ALIGNMENT LOAD AND AT EACH INCREMENT OF LOAD. THE SCHEDULE OF HOLD TIMES SHALL CORROSION PROTECTION. USE ZINC CLAD 11 ETHYL SILICATE INORGANIC ZINC -RICH COATING TO BE AS FOLLOWS: C.I.P. CAST IN PLACE 5.0 MIL THICKNESS ON ALL SOLDIER PILES. TIEBACKS SHALL BE DOUBLE COROSSION PROTECTED C.J. CONSTRUCTION JOINT O.C. ON CENTER LOCATE AND DISCONNECT ANY UNDERGROUND POWER, COMMUNICATION, GAS AND WATER LINES PER THE ATTACHED DETAILS. AL 1 MINUTE CL CENTER LINE O.D. OUTSIDE DIAMETER PRIOR TO DRILLING & EXCAVATION. CONTRACTOR SHALL VERIFY OVERHEAD CLEARANCES PRIOR 0.25 DL 1 MINUTE OR UNTIL STABLE CLG. CEILING O.F. OUTSIDE FACE TO MOBILIZATION AND CONSTRUCTION. 00602- WELDING 0.50 DL 1 MINUTE OR UNTIL STABLE CLR. CLEAR O.H. OPPOSITE HAND THE CONTRACTOR SHALL VERIFY THE EXACT ELEVATION, LOCATION AND SIZE OF ALL 0.75 DL 1 MINUTE OR UNTIL STABLE COL. COLUMN OPNG. OPENING UNDERGROUND UTILITIES OR STRUCTURES PRIOR TO SHORING INSTALLATION. TIEBBACKS SHALL WELDING SHALL CONFORM TO AWS D1-98 "STRUCTURAL WELDING CODE." WELDING 1.00 DL 1 MINUTE OR UNTIL STABLE CONC. CONCRETE OPP. OPPOSITE BE NO CLOSER THAN 3 FEET TO ANY UTILITY, UNLESS OTHERWISE SHOWN. ELECTRODES SHALL BE E70XX. ALL WELDING SHALL BE PERFORMED BY WABO AND AWS 1.25 DL 1 MINUTE OR UNTIL STABLE CERTIFIED WELDERS. ALL COMPLETE PENETRATION WELDS (CP) SHALL BE ULTRASONIC CONN. CONNECTION ORNT. ORIENTATION TESTED. ALL SINGLE PASS FILLET WELDS SHALL BE VISUALLY INSPECTED. MINIMUM WELD SIZE 1.50 DL 10 MINUTES CONST. CONSTRUCTION OSB ORIENTED STRAND BOARD 00301- DRAINAGE CONTROL IS 1/4" CONTINUOUS FILLET. AL = ALIGNMENT LOAD CONT. CONTINUOUS O.W.J. OPEN WEB JOIST DL =DESIGN LOAD THE CONTRACTOR SHALL TAKE MEASURES TO CONTROL ALL SURFACE WATER RUNOFF FLOW 00603- SUBMITTALS CTSK. COUNTERSINK AND FLOWS FROM EXISTING SUBSURFACE DRAINAGE FEARTURES INCLUDING PERCHED WATER. THE MAXIMUM LOAD IN A PROOF TEST SHALL BE HELD FOR 10 MINUTES. THE LOAD HOLD CTR. CENTER(ED) PAR. PARALLEL IN NO CASE SHALL THE CONTRACTOR ALLOW THE WALL SYSTEM TO BE EXPOSED TO SUBMITTALS FOR THE FOLLOWING ITEMS SHALL BE SUBMITTED FOR REVIEW AND APPROVAL PERIOD SHALL START AS SOON AS THE LOAD IS APPLIED AND THE ANCHOR MOVEMENT CY CUBIC YARD P/C PRECAST HYDROSTATIC PRESSURES OR ALLOW SURFACE WATER TO FLOW INTO THE EXCAVATION. PRIOR TO FABRICATION AND INSTALLATION; SHALL BE MEASURED AND RECORDED AT 1, 2, 3, 5, 6 AND 10 MINUTES. THE ANCHOR CMU CONCRETE MASONRY UNIT PEN PANEL EDGE NAIL MOVEMENT BETWEEN 1 AND 10 MINUTES SHALL NOT EXCEED 0.04 INCHES PER LOG CYCLE OF PERP. PERPENDICULAR 1. CONSTRUCTION SEQUENCE NARRATIVE & DESCRIPTION INCLUDING EQUIPMENT LIST AND TIME. IF THE ANCHOR MOVEMENT BETWEEN 1 AND 10 MINUTES EXCEEDS 0.04 INCHES, THE THE REGIONAL GROUNDWATER TABLE IS DEEP AT APPROX. 50 FEET BASED ON THE KEY PERSONNEL. MAXIMUM LOAD SHALL BE HELD AN ADDITIONAL 50 MINUTES. IF THE LOAD HOLD IS d PENNY (NAILS) PL. PLATE GEOTECHNICAL SITE INVESTIGATION. EXTENDED, THE ANCHOR MOVEMENT SHALL BE RECORDED AT EACH LOAD INCREMENT. DB DROPPED BEAM PL PROPERTY LINE 2. LEAN CONCRETE MIX DESIGN ACCEPTABLE PERFORMANCE WOULD EQUATE TO A CREEP OF 0.08 INCHES OR LESS DBA DEFORMED BAR ANCHORS PLMBG. PLUMBING 00400- BASELINE SURVEY AND MONITORING 3. CERTIFIED STEEL MILL REPORTS BETWEEN 5 AND 50 MINUTES. IF AN ANCHOR FAILS IN CREEP, RETESTING SHALL NOT BE ALLOWED. DBE. DOUBLE PLYWD. PLYWOOD 4. STRUCTURAL GROUT MIX DESIGN FOR TIEBACKS AS NEEDED DCW DEMAND CRITICAL WELD PSF POUNDS PER SQUARE FOOT GROUND MOVEMENTS ARE EXPECTED TO BE RELATIVELY SMALL AS A RESULT OF WALL PSI POUNDS PER SQUARE INCH CONSTRUCTION ACTIVITIES SINCE MOST OF THE CONSTRUCTIO N WILL NOT RESULT IN AN INITIA L 5. STRUCTURAL STEEL AND EMBEDDED ITEMS 5. THE ANCHOR SHALL BE UNLOADED AND LOCKED -OFF AT 90% TO 100% OF THE DESIGN LOAD. DEPT. DEPARTMENT P.T. PRESERVATIVE TREATED EXPOSED WALL FACE. HOWEVER, EXISTING STRUCTURES OR IMPROVEMENTS TO BE SAVED THAT DET. DETAIL ARE NEAR THE CONSTRUCTION ZONE SHOULD HAVE BASELINE PHYSICAL LOCATION DATA 00604- EXCAVATION DF DOUGLAS FIR PT POST TENSIONED) ESTABLISHED PRIOR TO BEGINNING WORK. AS A MINIMUM, OPTICAL SURVEY POINTS (POINTS DIA. / 0 DIAMETER KNOWN, OR PK'S) SHOULD BE ESTABLISHED AT THE CORNERS AND MIDPOINT OF THE RESIDENTIAL THE PROJECT CONSISTS OF A SOLDIER PILE RETAINING WALL TO PROVIDE SLOPE 00902 - VERIFICATION TESTING (200%) DIAG. DIAGONAL QTY. QUANTITY STRUCTURE AND AT '10-FOOT OFFSETS TO THE NORTH OF THE PK'S ON THE RESIDENCE ITSELF. STABILIZATION AT THE CREST OF THE BLUFF ON THE NORTH SIDE OF THE PROPERTY. i DIAPH. DIAPHRAGM THE SELECTION OF MONITORING POINTS SHOULD BE MADE WITH CONCURRENCE OF THE EXCAVATION WILL BE MINIMAL IN ORDER TO ESTABLISH PILES, AND INSTALL TIEBACKS AS TIEBACK LOAD VERIFICATION TESTS DIM. DIMENSION R. (RAD.) RADIUS GEOTECHNICAL ENGINEER. NECESSARY AT THE REQURIED LOCATIONS - AS INDICATED ON THE PLANS A VERIFICATION TEST SHALL BE COMPLETED ON AT LEAST ONE TIEBACK PRIOR TO THE RE: (REF.) REFERENCE INSTALLATION OF THE PRODUCTION ANCHORS. VERIFICATION TEST LOCATIONS SHALL BE DN. DOWN = -- THE MONITORING PROGRAM SHOULD INCLUDE MEASUREMENT OF CHANGES IN BOTH THE EXCAVATION SHALL PROCEED TO A DEPTH NO GREATER THAN 2'-0" BELOW THE ELEVATION OF SELECTED BY PANGEO INC. VERIFICATION ANCHORS MUST BE INSTALLED WITH THE SAME D.O. DITTO (REPEAT) _ C AND VERTICAL DIRECTIONS. THE MONITORING SHOULD BE PERFORMED AT LEAST ANY TIEBACK BEFORE STRESSING OF THAT AND ADJACENT TIEBACKS. LOCAL EXCAVATION AT A EQUIPMENT, CREW, MATERIALS AND TECHNIQUES AS THE PRODUCTION ANCHORS. DP. DEEP REQ. REQUIRED TWICE WEEKLY WHILE ACTIVE WALL CONSTRUCTION IS UNDERWAY, AND SHOULD BE INCREASED SOLDIER PILE IS ALLOWED TO A 2'-0" DEPTH AND A 2'-0" WIDTH AT THE TIEBACK FOR ADDITIONAL VERIFICATION ANCHORS SHALL BE INSTALLED FOR EACH COMBINATION OF R.F. RIGID FRAME TO DAILY MONITORING IF MOVEMENT IS DETECTED AT THE LOCATIONS OFFSET FROM THE INSTALLATION. TIEBACK MUST BE INSTALLED AND STRESSED BEFORE MAKING A SIMILAR LOCAL EQUIPMENT, CREW, MATERIALS AND DRILLING TECHNIQUES. WE RECOMMEND THAT THE D.S. DRAG STRUT R.O. ROUGH OPENING RESIDENCE. THE MONITORING SHOULD BE BY A LICENSED SURVEYOR, AND THE RESULTS BE EXCAVATION AT AN ADJACENT SOLDIER PILE. THE CONTRACTOR SHALL LIMIT THE OPEN FACE OF VERIFICATION TESTS BE COMPLETED IN EACH SOIL TYPE PRIOR TO INSTALLING DWG. DRAWING(S) PROMPTLY SUBMITTED TO THE GEOTECHNICAL ENGINEER FOR REVIEW. THE RESULTS OF THE THE EXCAVATION TO 4 FEET VERTICAL, UNLESS OTHERWISE APPROVED BY THE GEOTECHNICAL PRODUCTION ANCHORS IN THAT SOIL TYPE. DWL. DOWELS(S) R.S. ROUGH SAWN MONITORING WILL ALLOW THE DESIGN TEAM TO CONFIRM DESIGN PARAMETERS, AND FOR THE ENGINEER. CONTRACTOR TO MAKE ADJUSTMENTS TO MEANS AND METHODS OF CONSTRUCTION, IF VERIFICATION TESTS SHALL BE COMPLETED IN ACCORDANCE WITH THE POST TENSIONING {E} EXISTING SCH. SCHEDULE NECESSARY. REMOVE LEAN MIX FROM THE PILE TO ALLOW PLACEMENT OF STRUCTURAL CONCRETE. CARE INSTITUTE PTI "Recommendations for PrestressingRock and Soil Anchors". ELEMENTS OF THE ( ) SCHED. SCHEDULE BY THE EXCAVATOR SHALL BE TAKEN TO PREVENT EXCESSIVE POUNDING OR SHAKING OF THE TESTING AREAS FOLLOWS: EA. EACH SHORING WALL. E.E. EACH END SCL STRUCTURAL COMPOSITE 1. VERIFICATION TESTS SHALL NOT BE COMPLETED UNTIL THE TIEBACK GROUT HAS ATTAINED E.F. EACH FACE WOOD ANY VOIDS BETWEEN THE FACE OF THE EXCAVATION AND THE LAGGING SHALL BE FILLED WITH AT LEAST 50 PERCENT OF THE SPECIFIED 28-DAY COMPRESSIVE STRENGTH. SHT. SHEET AN APPROVED PERMEABLE, FREE DRAINING MATERIAL APPROVED BY THE GEOTECHNICAL E.J. EXPANSION JOINT Sim. SIMILAR ENGINEER. 2. VERIFICATION TESTS SHALL BE COMPLETED SUCH THAT MEASUREMENTS OF LOAD AND EL. ELEVATION S.J. SHRINKAGE CONTROL JOINT INSTALLED ANCHORS SHALL BE APPROVED BY THE GEOTECHNICAL ENGINEER PRIOR TO TIEBACK DISPLACEMENT CAN BETAKEN AT INCREMENTS OF 25 PERCENT OF THE DESIGN ELEV. ELEVATOR S� S) PROCEEDING WITH EXCAVATION. LOAD (DL) UP TO 200 PERCENT OF THE DESIGN LOAD. THE ANCHOR MOVEMENT SHALL BE EMBD. EMBED(MENT) MEASURED AND RECORDED TO THE NEAREST 0.01 INCH WITH RESPECT TO AN... S.O.G. N GRADE SLLABAB OON GROUNDWATER EN EDGE NAIL SPC. SPACE(S) (ING) THE GEOTECHNICAL REPORT INDICATES THAT THE GROUNDWATER TABLEN IS UNLIKELY TO BE ENG. ENGINEER SPEC. SPECIFICATION(S) ENCOUNTERED ABOVE THE BOTTOM OF EXCAVATION ELEVATION - LOCAL PERCHED EQ. EQUAL GROUNDWATER MAY BE ENCOUNTERED. REFER TO THE GEOTECHNICAL REPORT. AL 1 MINUTE EQPT. EQUIPMENT SQ• SQUARE 0.25DL 5 MINUTES E.W. EACH WAY STD. STANDARD 00700- SOLDIER PILES 0.50DL 5 MINUTES STGR. STAGGER 0.75DL 5 MINUTES EXP. EXPANSION STIFF. STIFFENER(S) 1 .00DL 5 MINUTES EXST. EXISTING SOLDIER PILES ARE TO BE INSTALLED IN 24 INCH DIAMETER HOLES PER PLAN. 1.25DL 5 MINUTES EXT. EXTERIOR STIR. STIRRUP(S) 1.50DL 5 MINUTES STL. STEEL THE SOLDIER PILE HOLES SHALL BE FILLED WITH LEAN MIX. ALL HOLES ARE TO BE DRILLED IN AN 1 .75DL 5 MINUTES STRUC. STRUCTURAL ACCEPTABLE MANNER WITHOUT LOSS OF GROUND AND WITHOUT ENDANGERING PREVIOUSLY 2.00DL 60 MINUTES FAB. FABRICATION STRUCT. STRUCTURAL INSTALLED PILES TO GEOTECHNICAL ENGINEERS SATISFACTION. ALTERNATE PILE PLACEMENT AT FB FLUSH BEAM SUSP, SUSPENDED(TION) LEAST 24 HOURS TO ALLOW CONCRETE TO HARDENED PRIOR TO DRILLING ADHACENT PILES. AL = ALIGNMENT LOAD... FDN. FOUNDATION SYMMETRICAL R-O A F.F. FINISH FLOOR SYMM. INSTALLATION TOLERANCES THE LOAD AS LOAD IS _ beer I SHALL BE AS FOLLOWS; -HOLD PERIOD SHALL START AS SOON THE APPLIED AND THE ANCHOR iAt� FIN. FINISHED} T• TOP PLAN DIRECTION 3 INCHES PARALLEL TO WALL MOVEMENT SHALL BE MEASURED AND RECORDED AT 1 MINUTE, 2, 3, 5, 6, 10, 20, 30, 50, AND FIN. LG PLR. FLANGE FLOOR T.&B. TOP AND BOTTOM 1 INCH PERPENDICULAR TO WALL 60 MINUTES. : 1 FN FIELD (PAGE) NAIL TEMP. TEMPORARY VERTICAL DIRECTION 1 1/2 /o OFTOTAL LENGTH, 3" MAXIMUM IN PANGEO INC. WILL EVALUATE THE RESULTS OF EACH VERIFICATION TEST AND MAKE AsEl ; F.O. FINISHED OPENING T.&G. TONGUE AND GROOVE DETERMINATION OF THE SUITABILITY OF THE TEST AND OF THE CONTRACTOR'S PROPOSED THK. THICK(NESS) ELEVATION PRODUCTION ANCHOR DESIGN AND INSTALLATION SYSTEM. TESTS WHICH FAIL TO MEET THE = F.O.C. FACE OF CONCRETE THRD. THREADED DESIGN CRITERIA WILL REQUIRE ADDITIONAL VERIFICATION TESTING OR AN APPROVED F.O.M. FACE OF MASONRY GROUNDWATER MAY BE ENCOUNTERED DURING DRILLING FOR SOLDIER PILES. THE REVISION TO THE CONTRACTOR'S PROPOSED PRODUCTION ANCHOR DESIGN AND F.O.S. FACE OF STUD TN TOE NAIL CONTRACTOR SHALL BE PREPARED TO USE TEMPORARY CASING OR OTHER METHODS TO KEEP INSTALLATION SYSTEM. IF AN ANCHOR FAILS IN CREEP, RETESTING WILL NOT BE ALLOWED. T.O.S. TOP OF (STEEL) (SHEATHING) THE SIDEWALLS OF THE HOLE OPEN WITHOUT SIGNIFICANT RAVELING OR CAVING. t r F.O.W. FRM. FACE OF WALL FRAME (FRAMING) T.O.W. (SLAB) TOP OF WALL PANGEO INC. SHALL BE PRESENT DURING DRILLING OPERATION TO VERIFY THAT THE A VERIFICATION TESTED ANCHOR WITH at 60 MINUTE LOAD HELD AT 2.0 DL IS ACCEPTABLE IF: r ll C F.S. FT. FAR SIDE FEET {FOOT) TRANSV. TRANSVERSE CONTRACTORS DRILLING METHOD AND PROCEDURES ARE APPROPRIATE FOR THE GROUND CONDITONS. a) THE ANCHOR CARRIES THE TEST LOAD WITH A CREEP RATE THAT DOES NOT EXCEED 0.04 INCH BETWEEN 1 AND 10 MINUTES AND 0.08 INCH OR LESS BETWEEN 6 AND 60 MINUTES. @ FRTW FIRE RETARDANT TREATED TY TYPICAL b) ALL TIME INCREMENTS SHALL HAVE A CREEP RATE THAT IS LINEAR AND DECREASING r WOOD WITH TIME. U.N.O. UNLESS NOTED OTHERWISE c) THE TOTAL MOVEMENT AT THE TEST LOAD EXCEEDS 80 PERCENT OF THE THEORETICAL n FTG. FOOTING U/S UNDERSIDE ELASTIC ELONGATION OF THE NON -BONDED LENGTH. C ca SHEETINDEX j GA. GAUGE FURTHERMORE, A PULLOUT FAILURE MUST NOT OCCUR FOR THE VERIFICATION TEST GALV. GALVANIZE(D) V. VERTICAL ANCHOR AT THE 2.ODL MAXIMUM LOAD. SHT SHEET NAME Issued Rev Rev Date co GB. GRADE BEAM VERT. VERTICAL SS1.0 Structural Notes 07/29/15 GLB GLUE LAMINATED BEAM VIF VERIFY IN FIELD PULLOUT FAILURE LOAD IS DEFINED AS THE LOAD AT WHICH ATTEMPTS TO INCREASE THE S52.0 Properties on SW 307th St 07/29/15 p TEST LOAD RESULT ONLY IN CONTINUED PULLOUT MOVEMENT OF THE TEST ANCHOR GRD. GRADE WITHOUT A SUSTAINABLE INCREASE IN THE TEST LOAD. SS2.1 Regan Property 07/29/15 7O GWB GYPSUM WALLBOARD W. WIDE (WIDTH) SS3.0 Reagan Elevations 07/29/15 GYP. GYPGRETE W/ WITH SS4.0 Shoring Details 07/29/15 W/O WITHOUT Grand total: 5 HD HOEDOWN WD• WOOD n W.H.S. WELDED HEADED STUDS H.D.G. NOT DIPPED GALVANIZED W.P. WORK POINT 8 HGR. HANGER W.S. WELDED STUD ") HORIZ. HORIZONTAL m HR HEADER WT.WEIGHT H.S.B. HIGH STRENGTH BOLT W.W.F. WELDED WIRE FABRIC HT. HEIGHTco X-STG EXTRA STRONG n XX-STG DOUBLE EXTRA STRONG I.D. INSIDE DIAMETER 2' N E. 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N 60 � .-C 60 O a-.' n c r O .---, w V) 03 V n N � V IL SS2mO Lo 0 0 N 6i N ti 1I CU E 0 ," it7 of __ 11--_ I- �:,-.Z\\ w_ I � -_ �` t't` _. - _ - - __ r_. - , - \� t ,\ ` l� i 0 _ - =, 1 i i Pile Schedule (Regan) _ _ Pile No Type Tieback Elevation Force No Load Length [ft] Min Bond Length [ft] R 01 W14X43 R 02 W14X43 R 03 W14X43 R 04 W14X43 R 05 W14X43 R 06 W14X43 R 07 W14X43 137.1 74.5K 20.0 30.0 R 08 W14X43 135.7 74.5K 20.0 30.0 R 09 W14X43 134.8 74.5K 20.0 30.0 R 10 W14X43 134.8 74.5K 20.0 30.0 R 11 W14X43 134.8 74.5K 1 20.0 30.0 R 12 W14X43 R 13 W14X43 R 14 W14X43 R 15 W14X43 NOTE 1. ALL PILES THIS PROPERTY ARE TO BE 60'-0" LONG PILES TYPICAL. 2. INSTALL TIEBACKS PER SCHEDULE - BOND LENGTHS NOTED ARE MINIMUM REQUIREMENTS - ACTUAL CAPACITY TO BE CONFIRMED IN THE FIELD WITH APPROVAL OF GEOTECHNICAL ENGINEER. %1 L\ 1 " \. \ t (' I / ,; � i 1-1/1 i Ij ___ ' 1 I 4 I _ _ - - ___-'__-- '- _ �, 111-1-1 ,.-" , ___ _,_ �, I - --,., 11 , - _. _�� - .-,- - -, __ - - _ - ___, -- -- -,. __. 11, ,. :ter,-,,,.,,,^` •�""" -/ •\ j -.. °A __ _ i °` _ - I - __ , � --l", __ __ _ yl _ 11� , - _ , 1*1-.. - - -..-, - -1 ",,-- - ", - ,." _. -, - ... - . , - _- __ , _ _ _ \ \ \\ ` - _ _- „_ ,._ .,,_ \ \ \, , \♦ �i a - _f_,�"�'*n \ . -- -- .awe" \ , < _` __„ _ a,�m, .vm,..o. a,.a,r„�+.. ,.maw+= .tee, -._. .,-_.._.-_ .._.-_.._' .-.-., " " I___. _._ - -' _ __. - °� \ — __ \ _ .ate _.. --.-. \ , __'__. .. --_._. _,._`_-_ _____ - -._ . _.___. _.-___ % _ _ _.-- , \ r _. \ \ _ "_-_ - 11 �� _.._ ._-. - -, - - - I _r __,_- _.._ , _._- _,_. e _--_'_-'---_ ' --_ _ _ -_ \ ', \ \ \ _ k•, -__-' - - _- - __- Jam^ \ \ , \ _ � r� ., ,_ -_ ._ �. aeaa - \ - .._- _.- - +mom "°k„a=a. 1 - - „. - -- - ., __ _ \ i _ _ _./ \ - ._ - - - _ _" .1 _ �_ __ _ w�a+^v+' w'.aoxwa �. .._ .._ _. - __ . a - - _. _.. _. _ �.a..,,,,,,. m \ \ _- _... \ 1F .� f y m4 , / , - _ -_ \� - _ - - _-, - _ - - - - __ 1 _._ i ,, \ \ ` \ ,. fit, _ „�,•. - _ _ !- - ..�.,x.,.•_ `"".w __.ry v \`�, c \ ,',i _ _ J., ,,_ _.. \ \. \ ,, , ✓utn L a .- ..,..._..._- ,.-. . °xpm+�em naatmw - ,W^ - _.., _ _ . _.-. -- __ -. _. .... - - _._ __ _ , I J .. -.._ ,_. ...- _ _.... 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'"..'°.e.�+ _ ' ' ......__ --- �Po`�°^., \ ! , �p -- -- -- w �._""" _ _ - _ - - - -.. \�\ \. ------ _ \ �- f N ti: '^ l _ _ _ ._ _ - PILES IN 24 dia._ _ __ __ __ _ _ _ e \ r\ PER ELEVATION 1 \. ! \ \ `\ \ - - ---'-- ---- - _ _ - - -_._ _- `v ,; \t �`"_� HOLES P �' \ \ \ \ - __-' - - _ _ _ _' w _ "� �i �. v , !\ '4 ' - \ fr J/ b' r e! ..._ . _...._.---- .,,,.__ i �\._". aW -_~''� ,,.. { -M \ \ \ a - w ..nw.as urw°w+' " \ \ ` s'--•+ t,t - - ^ , _� -.r: \ \ \ \ \ \--aresavn aruwaae°, _ .-.- .- . - or' - m., - f J �` q �.. _..__ - - , % ___- __.-__ _ 1 _ _ . _ w \ \ _. .._..... _ _ - _.. __ ,.,ate r - __ _ 1.1 i' _' - _.. - „ -,. I r w y _ ._. _... �,: ., \ 'y .__. __ _- r r ,ter+ �,. _ ` - - —, \ , , \ ,_, [ i - -- d ... ^---. -- - ^.m a%m� i- _. _. _.. -_'_- ..- / r „ „mow ', .,� �\ -- -�— - — �,_.� / _ r�. _ _ - ^. __ 11 \ \ e i_,. - , ,, , - "ter \ / - '11 _" \ - - — - • - _S_ - , J �- 1 R 02 �. \ - - _ _ _ - �- — R 0 R- 03 \ ',� ; f - � ' -1-1 __^ _ _ � . _ a • - -� -- i _ - �/ t i ' -l', R- 05 R- 06`, , - - --- ,,._.r ��. - \ I i _- W Z. , • -1 >� -ix� - to - i" , , - \ r `' • - - - - - - - R 1 __T . `: ' r. , _ ` _ � , - , R- 11 - 2 R- 13 R- 14 if • =T \ - R- 15 - .. cif \\ d� • - - - p; _ , r I - , _1. _._ _ y a✓ C° • ! - -'- = ' • .>, • --- ---- =� = ---- -- 4X LAGGING PER ELEVATION �s } I ,,.� «-" I" ; �_ , y< i J / ✓ J °' • • • • ! 11__,..__,/ .r __.. 11 if 11;�~ `\ • . 1 , • 0 • • BACKFILL TO MATCH ADJACENT _._._.__ - •� • • • GRADES AS NECESSARY \ • • • 1 • • `y • N J • �� • ' �M1 • • \ I _ __J ; ,, ! t I • /`� t • ° ! �t e 0 t v✓,._., . f t • s \ • ! � 1� _ ! ; qi N 1 ! , ; i ' \ 11 • • u • A� ", " • t • / • ! i J� __ __..-.____-w_ __..__. • 0 f • ! € j' ' � j �I � t t _ , --,,� , t •. j.., � s ( t_ __ ! ! ° ', I • • I i i = I v I s TIEBACKS PER SCHED & DETAILS • •' . -' _.._ � I ", I-) ni - • t, a - � -_ 0 4,11"._ I I � , I I I,j I • ! •� , f \r • •I I * ,� 1 i , 1e AAR - ; p, I / \ / , . //j ` \\ ! I I J f � t n 0 I . I I r.__ � __--_,,_. _ , � __ ,- � SCALE: 3/16" = V-0" I • _18--------_ • • • • _-_-•-__--___ _ _ ._, _ • • _�- _ I „ • • • 11, • • • • • _ - __ __ • - -- -- - - , � __ • • ! • • • • • • • • • • • • • • • • • • • • • • • • • • ! • • • • • • • • • • • 0 • • • • • • • • • • 9 • • • • ! • • • • • • ! • • • • • 0 • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 r n C _ ,, t1_ r I i f _\ ' r / ___, ,,, z o m 6— �v La) V? 7, NNE W M 0000 C.em-+N <D CU) R E Uj1' U a) M ,_SS C m `-" 0 .- � s u� -F + CO) U � et ,_ Z N v +--y' O f0 t FR F_ Q aur. r; - I m l N 1 0 __ " ,- v� � O v ! U ; --, L � C, •- 1 �? 1` 1 �? it- \ G b� W �_ Q Z O us W Z I o 11 66I Q I O f Ql z� f) Cl)jW oN GV� = D=O W 0 o Q U) >- :E Cr W U co Y a Cl- .W O . ^, ----) 1 ;_..� C�z a) EO m +¢ CN �o � r00 O (D __� r_- ( ) CN a) c —4 �2� ,,I,CJ. SS2ml Reagan _ 51 - 0" 140', R— 1 I 135' 1 130' ' 125' 120' 115' 110' 105' ( , 1NY 96 90' SCALE: 3/16" = 1'-0" I WX co E Elevation 1- a BACKFILL TO MATCH ADJACENT GRADE 140' 135' 125' 120' 105' z o z CO w -'S i cov N�00 U)� (U N W mC0O ON �CnN E U W N C U) s ` U U) __ 4 U0`5= U 0 .�U.. ZcN 22" L 0 4 - Cb (6 �A COO � N L ■ LO T (.41 w rn bk� H 0 z O us 0 z o Uj 0 i u c - Z Q �2 127 F- I- <( 0 rn o N rn O W m (D c Q U �- cr- pzQ C) 3 W U U) W Y o w U) d O o CD o c SS360 WHEN STRESSING TIEBACKS, ENSURE THAT LAGGING AND BACKFILL EXTEND AT LEAST 3ft ABOVE THE TIE -BACK LOCATION - DO NOT 18H LAG BETWEEN PILES AND STRESS WHEN THERE IS NO RETAINED SOIL 24" DIA. BACKFILL TO A MAX HEIGHT OF BEHIND TIE -BACK LOCATION TYPICAL U.N.O. DIA. PER SCHED. PILE PER 8ft AS SHOWN SCHEDULE W 14X PILE 46 LAGGING Q PER PLAN Zo :E TIEBACK W/ NO-LOAD FREE DRAINING TYP. BACKFILL ZONE PER DETAILS \ Q�RSONEpp�E PL 316' 1 /4" 2" X 6" O.C. DRAINAGE FABRIC SPECIFIED BY OTHERS SOLDIER PILE WALL ° a ( '` �. GBH P.T, 4X6 LAGGING a , ° (E)GRADE MAY SLOUGH OVERTIME ( II BQNp G ALE - INSTALL TIEBACK WHEN SOILS AT 8FT MAX FROM TOP OF PILE r(I I 0 4tiR5 - I WHEN GRADE SLOUGHS TO 8FT / W14 PILE MAX - INSTALL TIEBACK AT 8FT o FROM TOP OF PILE IMMEDIATELY / \ `„' m. P.T. 4X6 LAGGING OPTIONAL \ CONCRETE WALL FACING SCALE: 3/4" = 1'-0" SCALE: 3/4" = 1'-0" 1 TYPICAL PILE DETAIL 41 TYPICAL CORNER PILE DETAIL 2 ❑ \ BOTTOM OF EXPOSED WALL HEIGHT 5'-0" 6H (PSF) 0.4(1-X/H)q (E) GRADE OPTIONAL SEISMIC SURCHARGE CONCRETE WALL FACING PRESSURE PRESSURE ------------ ----- ---------------------------INCREMENT O J---------- 0 1:1 (MAX.) r INSTALL 2ND r' N PILE PER W PILE WEB o TIEBACK AS SHOWN 00 ( 27 PCF SCHEDULE o (LEVEL BACKSLOPE) 67 PCF W PILES PER PLANS IN- 0 at� x 5" DIA. SCHED.120 PIPE _ o 314" WEDGE TO SUIT ANGLE MAX. NOTCH IN FLANGE IS 31/4" 46 LAGGING TIEBAC- DO NOT NOTCH WEB ACTIVE PRESSURE PASSIVE PRESSURE K � ANCHOR ELEV. --- — - ---- STIFFENER PLATES NOT SHOWN FOR WHEN GRADE SLOUGHS TO 1-� 1 WHEN GRADE SLOUGHS TO 30FT MAX - CONSULT CLARITY 20FT MAX- INSTALL TIEBACKAT GEOTECHNICAL ENGINEER 30ft IS THE MAX 20FT FROM TOP OF PILE ------- "-j I ` I EXPOSED SHORING FACE WITH THIS SYSTEM - PLATES TO BE WELDED TO BOTH IMMEDIATELY FURTHER REMEDIAL ACTION WILL BE REQUIRED. FLANGES PER OTHER DETAILS SCALE: 3/4" = V-0" SCALE: 3/4" = 14" SCALE:1/16" = V-0' SCALE: 3/4" = V-0" 6 TYPICAL PILE DETAIL 7 POCKET DETAIL g Sequencepf Tieback Installation 1 p WALL DESIGN PARAMETERS - SINGLE TIEBACK ❑❑ 1 15-0" 18H CENTRALIZER MIN. 0.5" COVER (6) ENCAPSULATED STRANDS IN CORRUGATED SHEATH, 3" I.D. HDP 9 \ -NOMINAL WALL THICKNESS CORROSION INHIBITING GREASE AND 0.06° \ PLATE, PER WELD PLATE SCHEDULE, 0.06" WALL HOPE TUBING a v v a \\ Q�RSGN�Op�E TO FLANGES OPPOSITE SIDE FROM (6) BARE STRANDS ANCHOR TYP. BOTH FLANGES INTERNAL GROUT TUBE 4 SOLDIER PILE WALL INTERNAL GROUT TUBE \ SEE \ CEMENT WELD GROUT FIELD 4 �Rs PLATE ` ` ` GROUTED M P \ { SCHEDULE �� \ �\ \ 161SS4 d S;pnl CORRUGATED SHEATH, 3" LD. CEMENT CD HDPE 0.06" NOMINAL WALL GROUT FIELD ANCHOR HEAD THICKNESS 0.06' TYP. (3) SIDES a � GROUTED v STRAND GRIPPER 114" d HDPE ORGANIZER 4 GALV. COVER CAP Q \ (GROUT OR GROUT FILLED) a a ° POST GROUT LINE POST GROUT LINE \� ANCHOR PLIX7X0'-7° PLATE ANCHOR SECTION A -A ANCHOR SECTION B-B 6" DIA. SCHED.120 RE:17/SS4 e�i�p FAT/Fe PIPE WEDGE F)4 9�kFREE LENGTH BOND LENGTH \ WELDED TO FLANGE V BOTTOM OF EXPOSED WALL HEIGHT 4" DIA. X 1'-0" MIN. 7-6 PIPE WELDED TO BEARING PL 6H (PSF) 0.4(1-X/H)q { NO-LOAD LINE (E) GRADE SEISMIC SURCHARGE PL 3/4" STIFFENERS a //�j//JgT/Y/ PRESSURE PRESSURE INCREMENT 1:1 MAX. OPTIONAL (MAX.) * ALTERNATE TIEBACK LOCATION LEFT SHOTCREIE WALL a � 4 { �/� � � 0 �^ (LEVEL BACKSLOPE) & RIGHT OF WEB FOR EVERY OTHER FACING d d q./�/ //�/ 2„ R27 PCF PILE a///�// J/\ Q RqN© /� (8p 67 PCF PILE a B�� 4 W. N� OT OSb/z1 1 1 0�0 Weld Plate Schedule PILE PLATE WELD W 14X43 PL 5/801 /2 x 24" 3/8" d y� 27H (PSF) (PSF) END CAP ACTIVE PRESSURE PASSIVE PRESSURE NOTES: (EXCEPT FROM GEOTECH REPORT Ji 1. EMBEDMENT (Z) SHOULD BE DETEP,MINED BY SUMMATION OF MOMENTS AT THE BOTTOM OF THE SOLDIER PILES OR / AT GROUND ANCHOR LOCATION IF PRESEPT. MINIMUM PILE EMBEDMENT SHALL BE 60 FEET BELOW CREST OF BLUFF. (H+Z= 60 FT) 2. A FACTOR OF SAFETY OF 1.5 IS INCLUDED IN THE RECOMMENDED ALLOWABLE PASSIVE EARTH PRESSURE VALUE. a / INCREASE ALLOWABLE PASSIVE PRESSOR= BY 1N FOR RESISTANCE TO TRANSIENT LOADS, INCLUDING SEISMIC EARTH PRESSURE. O.C. MIN. 2'-0" FROM ';,-? / 3. SEISMIC EARTH PRESSURE IS THEINCREMENTAL VALUE; COMBINE WITH STATIC ACTIVE EARTH PRESSURE. NOTE: SPACER & CENTRALIZER 1U'-0 ALL PLATES SHALL BE ASTM A572 MATERIAL SPECIFICATIONS; OF BOND LENGTH MAX.1-0' FROM BTM. OF BOND �JJJ� J��\ \ a v / � Q�� 4. ACTIVE, SEISMIC AND SURCHARGE PRESSURES SHOULD BE APPLIED OVER THE FULL WIDTH OF THE PILE SPACING ABOVE STRAND = 0.6 IA, 7-WIRE, 270 KSI, ASTM A-722, LOW RELAXATION LENGTH <V THE BASE OF THE EXCAVATION, AND OVEF ONE PILE DIAMETER BELOW THE BASE OF THE WALL FACE. �//!� � / CORRUGATED SHEATH CONFORMS TO ASTM at792 A-2, HDPE. BEARING PLATE 5. PASSIVE PRESSURE SHOULD BE A'PLIED TO THREE TIMES THE DIAMETER OF THE VERTICAL ELEMENTS. CONFORMS TO ASTM A572.//� v 6. USE UNIFORM EARTH PRESSURE (F 150 PSF AND 200 PSF FOR LAGGING DESIGN WITH VERTICAL ELEMENTS SPACED AT LESS THAN OR EQUAL TO 6 FEET AND BETWEN 6 AND 8 FEET, RESPECTIVELY. p� 7. DESIGN ANCHOR ADHESION IS 2.511LFT OF 6" dia ANCHOR. SCALE: 3!4" = 1'-0" _SCALE: 3/4" = 1'-0" SCALE: 3/4"=81'-0" REFER TO REPORT TEXT FOR ADDTIONAL DISCUSSION AND RECOMMENDATIONS. X TYPICAL PILE REINFORCING AT TIEBACK 17 TYPICAL TIEBACK ANCHOR SECTIONS AND DETAILS 20 WALL DESIGN PARAMETERS MULTIPLE TIEBACKS Z o 00 m Cv 4)00 ANNC� CD Lr) W Cl) 00 C 4)N rco N E W 8' c t6`n�v i � C id4r "all U d LZ N 22U 4- c) S 20O 52 VJ N �.n l� 0) O 9' w H 0 i z 0 _vs 0 z �I U w ao _ Q Q Q W o N Cq C N O LLi m C� Q � >- r p z Q U W U 0 W Y o w cn a V.J 4-- c J M dN" SS400