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Home My WebLink AboutGEO2016-00018 - BLD Engineering / Geo-tech Reports - 4/11/2016 P� RECEIVED APR 1 12016 615 W. Alder Street CAS H M* CAU - TECHNICAL SERVICI✓ S Geotechnical Report 19061 E State Route 106, Belfair WCHAEt G4 oV WASC�.Q'� CHAEL 570 GIs[ R�� 50570 0 �� SStOSV AL L�yG �� GISTERti �� `sS�ONALti� Report Date: 1/21/2016 1 Dear Client, As requested, we have conducted a geotechnical soil investigation regarding the installation of push-piers to lift and level portions of the residence undergoing settlement. We conducted a site investigation and reviewed the findings by Geotechnical Testing Laboratory, conducted on 2/1/2005. We have concluded, based upon observations,that push piers are suitable for lifting and leveling the portions of the house undergoing settlement. While we observed no signs of slope movement that would indicate a problem besides vertical bearing failure of the foundation on soft soils, we recommend that you contact us immediately if settlement continues or if any of the shoreward retaining walls undergo movement or damage as the geotechnical report on 2/1/2005 addressed. We also observed a smaller retaining wall near the foundation of the residence which also should be addressed if signs of moment become apparent. We recommend inspecting the slope after significant storm events. We trust the information provided is sufficient for your current needs. If you have any questions please contact us. Regards, Cash M. Carr PE. z Geotechnical Engineering Study Regarding: Push Pier Installation Introduction This report presents the results of our soil investigation and geotechnical report for the proposed push pier installation.This report is intended to address the suitability of push-piers to address settlement issues of portions of the residence foundation. Site Description The site contains a single family residence located adjacent to a steep slope of loosely compact material with poor drainage characteristics. Trace gravels are present, but the material is primarily cohesive in behavior. This is consistent with material from past (ancient) landslides. This material can be a stability concern, but no signs of instability were observed on site. Cracks have been present in the foundation since before 2005, when Geotechnical Testing Laboratory performed a report in regards to a failed ecology block wall located at the shore. This wall was rebuilt and is in good condition. The presumed cause of failure was inadequate drainage. There is a smaller 4' retaining wall located adjacent to the deck of the residence. Site Geology The site at 19061 E State Route 106, Belfair 98528 sits above a Quaternary-aged landslide deposit (Qls) at the base of a 16% slope. According to the Washington Department of Natural Resources' Landslide Hazard Zonation Project this particular location of the Qls unit corresponds with the Alderwood Landslide, a deep-seated slide possibly caused by seismicity occurring 1.1ka. This unit comprises gravels, sands, silts, clays, and boulders within the slide body and toe. It is unstratified and 'jumbled,' loosely packed, unsorted, and its grains and clasts range anywhere from angular to rounded. Liquefaction features are also commonly included in this unit,though present liquefaction susceptibility for the site is classified as "very low to low" by the Department of Natural Resources. The site sits half a mile north of the Sunset Beach Scarp- a visible trace of the Tacoma Fault. The site falls into seismic design class C to D and seismic design category D2. 3 Risks While every effort has been made to define and quantify geologic risk to this site, unknowns may exist beyond the reasonable scope of investigation. We recommend that if this wall or the ecology block bulkhead are observed to experience movement or failure, that we be consulted immediately. We also recommend that downspouts, yard, and driveway drainage be tightlined to the beach or infiltrated a safe distance from slopes if not already. We recommend continued monitoring of retaining structures and slope and that we be contacted immediately if additional settlement takes place. While we did not observe signs of slope instability, geological information and soil type indicate that this is a risk for this site. Recommendations We recommend installing Grip-Tite push piers to underpin and level the existing foundation where settlement is greater than tolerable amounts. We recommend at least 7 piers in the proposed locations with additional piers recommended for levelness of these additional areas. Slab lifting by cementious injection is a recommended option for leveling the existing floor slab once the perimeter footings have been leveled. Soil Log Quaternary-aged landslide deposit (Qls) EXTENT OF HAND AUGER TEST. 4' 4 Load Calculations Pile Installation loads Pile service loads as uming lifted conduction Loading loading/it loading/It Ibs/rtA2 Tnbula Span ft unless noted Loading Ibs/tt^2 Tdbuta Span tt unless noted Roof Dead Load 15.0 8.0 120.0 Roof Dead Load 15.0 BA 1200, Floor Dead Load 2 floors 10,0 8.0 80.0 Floor Dead Load 1 floors) Boo Well Dead Load 15.0 18.0 270.0 Wall Dead Load 15.0 18.0 270.0 Weight of footing/slab 221.8 221.8 Weight of footing/slab 221,8- 221.8 Coheason on footing 150.0 1.2 175.0 Cohesson on footing 0,0 16.0 0.0 Soil Weight on Footino Ili 110.0 1.0 110,0 Soil Weight on Footing Ibs/ftA3 0.0- 110.0 Downdre N/A N/A N/A Downdrag 113.7 5.0 568.5 25%Floor Live Load 1 floor 10.0 8.0 80.0 25%Floor Live Load 3 flooro Live Load 80.0 Load on 1 1,0568 Load on l Load on pile 1,450.3 Foundation tributary span on pile,Load on Pile(length of foundation contributing loads on pits),Instillation Load on Pile 4.00 4,227.2 Ibe Service Load on Pile 400 5,801.2 Foundation Haight 3.0 tt Estimated ASTM rated force based upon foundation uplift 8,877.1 Total Uplift Span Engaged (estimated value based upon field observations)(Includes load redlstrabutlon)(considered for short term instalalion load$under careful observation) 12.001 it FS SETTLEMENT 1.6 PlIe Rated Capacity 70,000.0 Ibe IFS SETTLEMENT Greater than 1.6 JOK Pile DIA 2.9 In Pile thickness 0.1 In Es oun s modulus of Boll 250.0 psi K 1.0 dimentionaless L 12.0 144.0 In E 29 000 000.0 I 1.1 In14 1''-1 v t tAICHA-P Critical Buclln of Steel 15,839.7 ,� C Critical SuclIrl of Soil 52s 782.0 e5 04 WASy�� Total Critical Bucling Capacity of Ile 541821.7Ilb F3 buclln 1.5 y 2 FS said 1.2 Mln Plla Drive Force 12 681.6 lb DRIVE PILES UNTILL STRUCTURE LIFTS PER MANUFACTURER RECOMENDATIONS OR MAXIMUM 50570 DRIVE FORCE IS REACHED.IF LESS THAN MINIMUM CONSULT ENGINEER. 4�01, L'STE� � S" WAS C9 Max Allowable Drive Force0� ( leld,buckling) s1 58 333.3 lb. ONALti Max Allowable Deflection 0.2a In Drive/ASTM test ratio 0.70 hf Pile Predicted ASTM RESULT 8,877.1 lb. i ACTUAL ASTM TEST RESULT 0,0 50570 �CJ� �FCISTE�� FSS�ONALQ�G Page 1