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HomeMy WebLinkAboutGeotechnical Report -Portions - GRD Engineering / Geo-Tech Reports - 6/5/2009 { i t Geotechnical Report } If Prepared for: Properties NW of Gig Harbor, Ltd. F Site: 241 NE Alder Creek Lane Belfair, Washington I _ ®ate: I June 5, 2009 f by: Geotechnical Investigations Group f I f 241 NE Alder Creek Lane, Belfair,Washington CONTACT INFORMATION CLIENT INFORMATION Client: Properties NW of Gig Harbor, Ltd. Contact: Graham Mercado Telephone: (253) 851-2511 Facsimile: (253) 851-1984 Email Address: gmercado@centurytel.net Mailing Address: P.O. Box 188 Gig Harbor, Washington 98335 Site Address: 241 NE Alder Creek Lane Belfair, Washington 98528 Parcel Number: 123325000906 GPS Location: N470 26.0201, W 1220 50.057' PREPARER INFORMATION Project: 09-0040 Contact: Blaise Jelinek or Jason E.C. Bell Telephone: (360) 923-2561 Facsimile: (360) 754-1893 Email Address: blaisejelinek@gmail.com Geotechnical Investigations Group 2 5933 54`1'Way SEE, Lacey, Washington 98513 Office ,360) 923-2561 Cellular(360)481-7062 241 NE Rider Creek lane, Belfair,Washington INTRODUCTION This report summarizes the results of our geotechnical consulting services. The existing structure (single-family residence) is under a Do Not Occupy order (Dec-17-2007) from the Mason County Department of Community Development. The emergency activity response is due to the onsite landsliding of saturated soil. Earth movement occurred approximately 2 years ago destroying the wing section of an existing soldier pile retaining wall, see photo below. j I The subject site is located at 241 NE Alder Creek Lane, Belfair, Washington 98528. The report has been commissioned by Graham Mercado of Properties NW of Gig Harbor, Ltd. •L Scarp, Wing Wall ViewLooking Southwest T he GPS location of the site is shown reiative to the surrounding area on the Vicinity Map, Figure 1 (near the end of this report). The layout of the site is shown on the Site Plan, Figure 2. A cross section is presented as Figure 3. Figure 4 is the approximate as-built drawing for the existing soldier pile retaining wall. The focus of the investigation was to determine the cause of failure and the resulting impact on the existing structure. The report concludes with drainage recommendations to reduce the probability of future failures. Specifically, our scope of services for this project includes the following: • Review the existing site-specific geotechnical report by Krazan and Associates, Inc. (November 15, 1999), the soldier pile design by Civiltech Corporation (May 30, 2000) and the addendum by Krazan and Associates, Inc. (February 3, 2000). • Review the published geologic, hydrogeological, and geotechnical data for the site area. Inspection of aerial photographs and LiDAR images. • A geologic reconnaissance of the site area and surrounding vicinity. • Site plan and cross section development. • Investigation and identification of shallow subsurface conditions at the site by characterizing the exposed soil and by reviewing published well logs. • Laboratory grain size analyses for soil samples collected from the site. • Evaluation of the landslide, erosion, and seismic hazards at the site per the Mason County Critical Areas Ordinance regulations (December 27, 2006). Geotechnical Investigations Group 4 5933 54'h Way SE, Lacey, Washington 98513 Office (360) 923-2561 Cellular(360)481-7062 241 NE Alder Creek Lane, Belfair, Washington • Geotechnical recommendations for site grading including site preparation, subgrade preparation, fill placement criteria (including hillside grading), temporary and permanent cut and fill slopes, typical drainage and erosion control measures. 17.01.100E5(l) --A discussion of general geologic conditions, specific soil types, ground water conditions, the upslope geomorphology and location of upland waterbodies and wetlands, and history of landslide activity in the vicinity. SITE CONDITIONS j i GENERAL The site is located along the hills east of the eastern portion of the Hood Canal in Mason County. The parcel (1.99 acres) is situated on a point overlooking the northwest to west trending stream drainage. The site is approximately % mile south of the center of Belfair, Washington. The site is accessed from the three existing driveways off NE Alder Creek Lane; the nearest cross street is State Highway 3 (WA- 3) A site reconnaissance was conducted on November 4, 2008. An additional site reconnaissance was conducted on April 29 and May 19, 2009. Test pits were sampled by Jelinek and Levine on May 19, 2009. The site is currently bordered by a residential parcel to the northwest. Forested (undeveloped) parcels - are located to the north, east, and south (see Figure 2 Site Plan). The current single-family residence is uninhabited. The eastern slope demonstrates signs of landsliding, specifically the block slump type, see photo below. Therefore, Mason County requires that a geotechnical report be prepared in accordance with the Critical Areas Ordinance (17.01.100E1a). af� 91. asp s y, Y • Eat. 3.•..f. .. "•':'. _ - �� _ -" k,� A soldier pile retaining wall is located 9 feet to the northeast of the residence, see photo next page. The wall was to protect the existing residence. The original geotechnical report was by Krazan and Associates, Inc. (November 15, 1999). The design was reviewed and stamped by Civiltech Corporation (May 31, 2000). The retaining wall was completed in 2000 by DBM Contractors, Inc. A copy of the available geotechnical report and retaining wall design may be obtained from Mason County at: http://www.co.mason.wa.us/forms/Community_Dev/research_request.pdf Geotechnical Investigations Group 5 5933 54'0 Way SE, Lacey, Washington 98513 Office(360) 923-2561 Cellular(360)481-7062 4 241 NE Alder Creek Lane, Belfair,Washington IM r` r ti ''i-.. s taw * a 3 E w.Looking Southeast y The existing retaining wall was examined for signs of deflection and failure. All support pile was measured to be plumb. The wood lagging appear unaffected; no drainage material was visible though the gaps. Other than the wing section, the wall does not appear to be adversely impacted by the new slumping. Since the wall has not moved, then the existing residence has not been impacted by the new slumping. SURFACE CONDITIONS The subject parcel is located along a west, north, and east sloping hillside. The topographic ridge follows the upper portion of Alder Creek Lane to the south of the parcel. No upland water bodies or wetland features were observed during the site reconnaissance or through the inspection of aerial photographs within 1,000 feet of the parcel. The onsite structures are located on multiple benches. The single-family residence is situated on the uppermost eastern portion. The garage is located to the northwest and downhill of the residence. A sauna, shed, and pond are located in the southwestern portion of the site. Site elevations range from 120 feet in the north to approximately 200 feet in the southeast. The general topography of the site area indicates that drainage flows toward the west, north, and east from the existing residence towards the northern drainage, see photo below. j 1 vew ooidng Northeast , Geotechnical investigations Group 6 5933 54th Way SE, Lacey, Washington 98513 Office (360) 923-2561 Cellular(360)481-7062 241 NE Alder Creek Lane, Bet€air,Washington The site is well vegetated with native and introduced flora species. A manicured lawn surrounds the residence. From the residence, the site slopes to the west, north, and east. Sections of the site slopes are nearly 48 percent. Slump < scarps are located along the top of the eastern slope (see - photo right). The existing residence is located where the : slope ranges from 0 to 2 percent. The existing septic drainfield is located in the level lawn area to the southeast of -' I the residence. A landslide scarp is approximately 6 feet from 14 the assumed septic drainfield location. The site was inspected before and after the wet season. The I purpose of the site inspections was to physically observe the =s >Uc Drainfield.A, , property and adjacent properties and to identify geologic and � � _` hydrogeologic conditions. Visual observations were x"`; documented and photographed. Site-specific features were mapped and the vegetation noted. i The lower eastern slope exhibits evidence of older landsliding. The sliding most likely occurred ~ between 10 and 20 years ago; re _� ' vegetation has occurred over most of the landslide debris. In _ r multiple locations, younger trees = - are straight and vertical. Recent Riga } shallow block slumping was Kam` observed along the eastern slope; -the headscarp has not re- vegetated. Two tight-line pipes terminate near the new slump pipe two (2) is shown in the photo right. View Looking North X i Geotechnical Investigations Group 7 5933 54"'Way SE, Lacey, Washington 98513 Office (360) 923-2561 Cellular(360)481-7062 I f 241 NE Alder Creek Lane, Beifair,Washington ONSITE INFILTRATION The subsurface infiltration features were identified at the site and plotted on the lawn. The septic drain fields (primary and secondary) are located in the southeast corner of the parcel. The primary septic drain field measures approximately 150 square feet; the secondary drainfield is estimated at 150 square feet The existing sewer system has been unused for many months due to the Do Not Occupy Notice. Previously, septic effluent may have contributed to the recent earth movement. Suspected areas of saturation are labeled in the photo below. 6m j ;rs Septic Drainfieid x � ✓°� '7 Yam` F�.���� "' _ .. � s Geotechnical Investigations Group 8 5933 54`"Way SE, Lacey, Washington 98513 Office (360) 923-2561 Cellular(360)481-7062 i 241 NE Alder Creek Lane, Belfair,Washington FIGURE 1 VICINITY MAP LkS Ai* ifs^ 'lt - _ i• ' ' ✓�'if r �1 �� i�.' ��1 �tr� � t � f � rfi!� r � 4: ! _ rl . Or � � f� � '�';• - ,✓ o � r . ,fir r}� � ✓�.�r i ' IV_°y - 7 t�a r ,� r a��, •� � F � f r r�t � - �i -^ • A", 1Aft Y i J fil 1 WA - 3 - r ! 6", Sie Alder Creek Lane z WA- 10 ` WA- 3 i Geotechnicai Investigations Group xii � 5g1' 5411) ,j\ipv SF i ;�r.15v UVai-,hinntnn r,8r•#,� I DATUM FOR THE SITE PLAN INCORPORATED VARIOUS TECHNIQUES AND SOURCES INCLUDING THE FOLLOWING: --- TAPING AND PACING,SLOPE MEASUREMENTS WITH AN - INCLINOMETER,ANGLES AND BEARINGS USING A BRUNTON@ GEO TRANSIT,SITE LOCATIONS USING A GARMINO HAND HELD GPS UNIT,TOPOGRAPHIC MAPS FROM DELORMEO,MASON COUNTY / G.I.S.WEBSITE,AND SURVEYS RECORDED AT THE MASON COUNTY ASSESSOR.GEOLOGIC SITE RECONNAISSANCE OCCURRED ON APRIL 29 AND MAY 19,2009 BY JELINEK AND LEVINE. /THE PRESENT RECORDED SURVEY WAS CONDUCTED BY I.OVITT. SHORT PLAT C 491 IS DATED JANUARY 1985. / / NORTH SCALE 1'-44Y / C.I.=10' 0 10 20 30 40 / /' i' _�------- / / 55%SLOPE LANDSLIDE Q) �' /'GARAGE HAZARD-A It It % A.' 49°/d SLOP (7) EXISTINI HOME SEEP SAUNA ' -- A PCNN LINE i POND HED ! r�q s, S ,� . ' , r ` 1zSEEP i ----------- ... / .. ; - ,352.54 --Ago ALDER CREEK LP Geotechnical Investigations 75.61' -120- Group t t \\ t 73p \ \ 1 t t t \ \ \\ Hydrogeological Geotechnical& Environmental Services \•Cb c 5933 54th Way SE )SLIDE \ ��G1O� a \\ Lacey,Washington 98513 �RU A \ Phone:(360)923-2561 ` ` 7 I Email:blaisejelinek@gmail.com 4 - 729e SLOP4NOLD(-1999 \ ` l LAND$LMEt ` LO \\ /T \ \\ t ,i itt 44%SLOPE N `\43%SLOPE I DRAIN F t' `\ \ 7 \ t �,4 �� ,Q1s \s'9 t •�\ b'\ , \ \ \ LANDSLIDE \\ \ I SL LAN IE E DEB"\ .ISTING �� \ `\ RDAREA )ME TREE �.IE PROJECT NAME: 0 SLUN D$ VE� .,. `� - �\ , \ PROPERTIES NW of GIG P, T1GF�LIE 1� ��CDYL�WIA T \ \ \ \ \ \ ```QQQ IIB�'�p�s� D HARBOR, Ltd. %SLllIMhE \y\`\ j `\ `\ 241 NE ALDER CREEK LANE SEW RLINE j,11, \• � \\ BELFAIR,WASHINGTON A \j\ \ , Qga Glacial Adv�:gce 011twash PARCEL 12332-50-00906 LINE EXISTING DRAINFIELD \• ` ` `\ ` LANDSLIDE Revisions: H RD AREA o \ 52%SLOPE P6G7� ` , \ \ ` \ SCALE:1 inch=40 feet ' LAN G \ i . �00 FIGURE 2 SITE PLAN E SOUTHWEST PROPERTY LINE NORTHEAST 210 . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . I . . . . . . . . . 210 200 ............................................... ................................ .......................... ................................................ .................... ..........................................................1 200 I 190 St m, . PROPOSED RETAINING WALL. I .I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 LANDSLIDE SEWER LINE (I LANDSLIDE 180 S 'HAZARD- : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . 180 170 SILTY SAND W/GRAVEVEGETATED AREA . . . . . . . . . . . . . . .. 170 160 Z-: .. . . . . . . . VEGETATED . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . SILT 160 150 ................. 44%SLOPE ................................. . ..... ............ ....... ....................................................... ................. .......................................................................... VEGIETATIED 150 DEBRIS VEGETATED 140 . . . . . . . . . . . . ST EAM. . . 140 1 130 30 0 -150 1100 1150 1200 250 300 CROSS SECTION A Geotechnical Investigations Group FIGURE 3 Geotechnical, 5833 54th Way SE Lac.y.WA 88513 CROSS SECTION Hydrogeological,& Phcm.:(360)481-7062 SCALE Environmental ServlCeS Email:bladsojelln k&m.11— 40' W 14X43 I i—^I 8 1/4' 7/16" T 7 I - 12 9/16' 13 1/2' SIDE VIEW FRONT VIEW SCALE .--�� 1/4' FENCE MUD U E MUD LINE ------ -------- --------------- -------- ------ DAMAGED WOOD LAGGING WING SAND FILE ANCHOR 3 ' I I I I I I I I I I I I I I I I I I I I i t I I I I I I I I I I I I I I 1 1 I I I I I I I I to�a�0� 53.5' I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 1 I I I I I I I I I I I I I I i t I I I I I I I I I I I I 1 1 I I I I I I I I I I I I I I 1 1 I I I I I I I I I I I I I I 1 1 I I I I I I I I i t I I I I 1 1 I I I Imo' 1 1 I I I I I I I I 1 1 I I I I I I I I l i I t I I I I I I I I i t I I I I I I I I I I I I I I i t I I I I I I 1 1 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II II II II II II II II I I CAST IN CONCRETE I I I I CAST IN CONCRETE I I I I I I I I I I I I I I I I I I I I I 1 1 I I I I I I I I I I I I I I I I I I I I i i I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I Li LJ LJ LJ LJ LJ LJ LJI Geotechnical Investigations Group FIGURE 4 Geoteceoloai, 5933541h Way 513 EXISTING SOLDIER PILE DETAIL Hydro edo ica1,8 Ph_Y'WA)4813 9 9 vroR:(3sol+e,-zosz Environmental Services E-11-bW-j,'1 ekQg aJ1 mm SCALE 1'=8'