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Home My WebLink About03195 - Technical Information Report - Geotechnical ► � �� -.-� '. �i 1�C _.. ` DEVELOPMENf Pl�`NN1NG I CITY OF RENfTON OCT 2 7 2004 RECEIVED GEOTECHNICAL ENGINEERING STUDY LAURELHURST SINGLE-FAMILY RESIDENCE DEVELOPMENT 138T" AVENUE SOUTHEAST AND SOUTHEAST 132ND STREET RENTON, WASHINGTON E-10988 January 28, 2004 PREPARED FOR �: , ` _� d�fas;;� . CONNER HOMES ��%'^`'�?�-- .,/ �'�;;-,.�, ;.�/ �:�.``, �� t.�, 5� �Y. �`,/�f.�: -f \+_ , 1 ,_ �:. :��+��=� �--� ��.,�1 � , . ;:�-��_�,:�x�,�,,� % --,,. �\�.\ttyne°'r'"c"v;,'�; ``� � �+.L 1�� P �_ ��`S �t 2(J�� __ Scott D. Dinkelman, LEG con Dinke�mun Associate Principal ,� ,� : r. A`�v��jF ��°� �qSy�'�o��' � ^ � � �� z � ao — K � 339�2 0 � ��✓ �—'1�� . l��i-�� ! L 8�0 l fy Kristina M. Weller, P.E. Project Manager ��`��`�� :....':��'-�� Earth Consultants, Inc. 1805 - 136th Place Northeast, Suite 201 Bellevue, Washington 98005 (425) 643-3780 Toll Free 1-888-739-6670 � - 3i ys � _ ' � IMPORTANT INFORMATION � ABOUT YOUR GEOTECHNICAL ENGINEERING REPORT More construction problems are caused by site subsur- technical engineers who then render an opinion about face conditions than any other factor. As troublesome as overall subsurface conditions, their likely reaction to subsurface problems can be, their frequency and extent proposed construction activity, and appropriate founda- have been lessened considerably in recent years,due in tion design. Even under optimal circumstances actual large measure to programs and publications of ASFE;% conditions may differ from those inferred to exist, The Association of Engineering Firms Practicing in because no geotechnical engineer, no matter how the Geosciences. qualified,and no subsurface exploration program, no The following suggestions and observations are offered matter how comprehensive,can reveal what is hidden by to help you reduce the geotechnical-related delays, earth, rock and time. The actual interface between mate- cost-overruns and other costfy headaches that can rials may be far more gradual or abrupt than a report occur during a construction project. indicates. Actual conditions in areas not sampled may differ from predictions. Nothing can be doae to prevent t�ie unanticipated, but steps can be taken to�ielp minimize their A GEOTECHNICAL ENGINEERING �rnpact. For this reason, most experienced owners retain tfieir REPORT IS BASED ON A UNIQUE SET 9eotechnical consultants through the construction stage, to iden- tify variances, conduct additional tests which may be OF PROJECT SPECIFIC FACTORS needed,and to recommend solutions to problems A geotechnical engineering report is based on a subsur- encountered on site. face exploration plan designed Eo incorporate a unique SUBSURFACE CONDITIONS set oF project-specific factors. These typically inc{ude� the general nature of the structure involved, its size and CAN CHANGE configuration; the location of the structure on the site and its orientation; physical concomitants such as Subsurface conditions may be modified by constantly- access roads, parking lots, and underground utilities. changing natural forces. Because a geotechnical engi- and the level of additional risk which the client assumed neering report is based on conditions which existed at � by virtue of limitations imposed upon the exploratory the time of subsurface exploration,construction decisions program. To help avoid costly problems,consuh the s►inuld not he based on a geotecFinical engineering report whose geotechnical engineer to determine how any factors adequacy may j�ave heen ajfected by ti►ne. Speak with the geo- ,I which change subsequent to the date of the report may technical consultant to leam if additional tests are � affect its recommendations. advisable before construction starts. Unless your consulting geotechnical engineer indicates Construction operations at or adjacent to the site and otherwisz, your geotedinical engineering report shnuld not natural events such as floods, earthquakes or ground- be usecl: water fluct�ations may also affect subsurface conditions •When the nature of the proposed structure is and, thus, the continuing adequacy of a geotechnical changed, for example, if an office building will be report. The geotechnical engineer should be kept erected instead of a parking garage,or if a refriger- apprised of any such events,and should be consulted to ated warehouse will be built instead of an unre- determine if additional tests are necessary� frigerated one; •when the size or configuration of the proposed GEOTECHNtCAL SERVICES ARE structure is altered; PERFORMED FOR SPECIFIC PURPOSES •when the location or orientation of the proposed AND PERSONS structure is modified: •when there is a chan�e of ownership,or Geotechnical engineers' reports are prepared to meet •for application to an adjacent site. the specific needs of specific individuals. A report pre- Geotechnical engineers cannot accept responsibility jor problems parecl for a consuiting civil engineer may not be ade- which may develop i(they are not consufted a/ter factors consid- quate for a construction contractor,or even some other ered in their report's development have chan_qed. consulting civil engineer. Unless indicated otherwise, this report was prepared expressly for the client involved and expressly for purposes indicated by the client. Use MOST GEOTECHNICAL "FINDINGS�� by any other persons for any purpose,or by the client RRE PROFESSIONAL ESTIMATES for a different purpose, may result in problems. No indi- vidual other than the client should appty this report jor its Site exploration identifies actual subsurface conditions intended purpose without�irst conferring with the geotechnical only at those points where samples are taken,when engineer. No person should apply this report(or any purpose they are taken. Data derived through sampling and sub- other than that original(y contemplated u�ithout�trst conferring sequent laboratory testing are extrapolated by geo- wifh the geotechnical engineer. _� • I a��: I ' P�,�__ �' 1 �c�l ll I l�l�t l��illc�i 115, it li cXxx<Y�hnical k-]i�incrrs.<;c��k�;i�s fi I�:nvir<��nici�u . � i i��nstru�li�N�l�ctilin};h 1C�13f1 1�n�.�i3(l Inti�xtlic�n ti , .. .� ,-. .�.-. . — . '- -. - .- I 846 - 108", A� Bellevue, Washington 9800�� Attention: Mr. Paul 011est� Dear Mr. Oilestad: Earth Consultants, Inc. (ECI} is pleased to submit our report titled "Geotechnical Engineering Study, Laurelhurst Single-Family Residence Development, 138t'' Aven�. Southeast and Southeast 132"d Street, Renton, Washington". This report presents tf results of our field exploration, selective laboratory tests, and engineering analyses. Thc purpose and scope of our study were outlined in our December 24, 2003 proposal. We understand it is planned to develop the approximately 30-acre, irregular shaped site with a new residential development. Review of preliminary design information indicates the proposed residential development will consist of one hundred thirty-nine (139) single-family residence lots, two stormwater drainage tracts, and associated arterial roadways. Based on the results of our study, it is our opinion the site can be developed generally as planned. Support for the future single-family residences can be provided using conventional spread and continuous footing foundation systems bearing on competent native soils or on newly placed structural fill used to modify site grades. Slab-on-grade floors may be similarly supported. We appreciate this opportunity to be of continued service to you. If you have any questions, or if we can be of further assistance, please call. Respectfully submitted, EARTH CONSULTANTS, INC. I Scott D. Dinkelma , G Associate Principal SDDlKMW/csm 1805 136th Place N.E., Suite 201, Bellevue,WA 98005 Bellevue(425)643-3780 FAX(425)746-0860 Toll Free(888)739-6670 � TABLE OF CONTENTS E-10988 PAGE INTRODUCTION.................................................................................................... 1 General ........................................................................................................... 1 ProjectDescription ........................................................................................... 2 SITE CONDITIONS ................................................................................................ 3 Surface ........................................................................................................... 3 Subsurface ...................................................................................................... 4 GeologicReview.......................................................................................... 4 SoilReview................................................................................................. 5 Subsurface Exploration................................................................................. 5 Groundwater.................................................................................................... 6 LaboratoryTesting............................................................................................ 6 CRITICAL AREA CONSIDERATIONS........................................................................ 7 Geologic Hazard Review.................................................................................... 9 SteepSlopes.............................................................................................. 9 Erosion Hazard Areas .................................................................................. 10 Landslide Hazard Areas ............................................................................... 1 1 Seismic Hazard Areas.................................................................................. 1 2 CoalMine Hazards...................................................................................... 12 DISCUSSION AND RECOMMENDATIONS............................................................... 12 General .......................................................................................................... 12 Site Preparation and General Earthwork ............................................................. 13 SlopeFill Placement......................................................................................... 15 Foundations .................................................................................................... 15 Slab-on-Grade Floors........................................................................................ 16 RetainingWalls ............................................................................................... 17 Seismic Design Considerations.......................................................................... 17 GroundRupture .......................................................................................... 18 Liquefaction ............................................................................................... 18 Ground Motion Response............................................................................. 18 Excavations and Slopes.................................................................................... 19 SiteDrainage .................................................................................................. 20 Utility Support and Backfill ............................................................................... 21 PavementAreas .............................................................................................. 21 Earth Consultants, Inc. � I . TABLE OF CONTENTS, Continued E-10988 � LIMITATIONS ..................................................................................................... 22 Additional Services .......................................................................................... 22 ILLUSTRATIONS Plate 1 Vicinity Map Plate 2 Test Pit Location Plan Plate 3 Slope Fill Placement Plate 4 Retaining Wall Drainage and Backfill Plate 5 Typical Footing Subdrain Detail APPENDICES Appendix A Field Exploration Plate A1 Legend Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY LAURELHURST SINGLE-FAMILY RESIDENCE DEVELOPMENT 138T" AVENUE SOUTHEAST AND SOUTHEAST 132ND STREET RENTON, WASHINGTON E-10988 INTRODUCTION General This report presents the results of the geotechnical engineering study completed by Earth Consultants, Inc. (ECI) for the proposed Laurelhurst single-family residence development to be located south and west of the intersection of 138`h Avenue Southeast and Southeast 132"d Street in Renton, Washington. The general location of the site is sho��r, on the Vicinity Map; Plate 1 . The purpose of this study vvas to explore the subsurface conditions at the site, and based on the conditions encountered, to develop geotechnical engineering recommendations for the proposed single-famil . �� '< < �: :! a, � ' , �� ; � �� . • Assessing the suitability of existing on-site materials for use as structural fill and providing recommendations for imported fill materials; • Providing seismic design parameters, including an evaluation of potential liquefaction hazard; � Providing site preparation, grading, and earthwork procedures, including stripping depth recommendations and details of structural fill placement and compaction; • Addressing short-term and long-term groundwater management and erosion control measures; � Providing foundation design recommendations, including bearing capacity and lateral pressures for walls and structures; Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E �1 0988 January 28, 2004 Page 2 • Estimating potential total and differential � � � �� ,�f� ' f.� � • Preparing pavement design recommendati Project Description We understand it is planned to redevelop a portion of the approximately 30-acre, irregular shaped site with a new residential development. Based on preliminary design information, the proposed development will include up to one hundred thirty-nine (139) single-family residence lots, two stormwater control tracts, and associated asphalt- paved arterial roadways. Review of the preliminary site plan indicates, up to seventy (70) of the proposed lots will be located on the west side of 138"' Avenue Southeast and the remaining sixty-nine (69) lots will be located on the east side of 138"' Avenue Southeast. At the time our study was performed, the site, lot and road configurations, proposed tracts, and our exploratory locations were approximately as shown on the Test Pit Location Plan, Plate 2. Based on our experience with similar projects, we anticipate the single-family residences will be two to three stories in height and will be of relatively lightly-loaded wood frame construction with a combination of slab-on-grade and wood joist floors. We anticipate wall loads will be on the order of 2 to 3 kips per lineal foot and coiumn loads will likely be in the range of 20 to 40 kips. We estimate slab-on-grade floor loads will be around 150 pounds per square foot (psf). The proposed site improvements will also include storrnwater drainage tracts. The proposed stormwater tracts will be located in the immediate southern portion of the site in the areas designated as Tracts U and V on accompanying Plate 2, Test Pit Location Plan. The site will be accessed from six entry points along 138"' Avenue Southeast (Duvall Avenue Southeast) in the central portion of the site, from one entry off of Southeast 132"d Street in the northeast corner of the site, and from B�emerton Place Northeast in the west central portion of the site. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 3 If the above design criteria are incorrect or change, we should be consulted to review the recommendations contained in this report. In any case, ECI should be retained to perform a general review of the final design. SITE CONDITIONS Surface The subject site consists of an approximately 30-acre, irregular shaped site located to the west and east of 138`h Avenue Southeast in Renton {see Plate 1, Vicinity Map). The proposed development areas are separated by 138"' Avenue Southeast which extends around 1 ,630 feet in a north-south direction through the center of the development area. The site currently contains eleven (1 1) single-family residences and numerous outbuildings that will be removed as part of the planned development. The east-central portion of the site contains an additional single-family residence that is to be incorporated into the proposed residential development. The western half of the proposed development extends three hundred (300) to six hundred (600) feet in an east-west direction from the west side of 138th Avenue Southeast to an existing residential development to the west. This portion of the site is bounded to the north by undeveloped forest, to the south and west by existing single-family residences, and to the east by 138"' Avenue Southeast. The east half of the site extends to around 635 feet east of 138`h Avenue Southeast. The east half of the subject property is bounded to the north by Southeast 132nd Street, to the east and south by residential developments, and to the west by 138tn Avenue Southeast. The predominate topographic features in the western half of the site consist of an elongated knoll (northwest-southeast trending) in the northern portion of the site, a ' roughly cylindrical knoll in the southern portion of the site, an east-northeast trending '� drainage that separates the two topographic high points, and an approximately 25 foot high steep slope area in the immediate southwestern corner of the site. The overall gradient of the western half of the site slopes primarily to the west-southwest at gradients generally in the range of 10 to 20 percent. Earth Consutta�ts, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 4 The northeast trending drainage that separates the northern and southern knoll descends to the west-southwest but is bordered to the north by a south facing slope that forms the southern flank of the northern knoll. The south side of the drainage consists of a north-facing slope that extends up to the center of the southern knoll. To the east of the knolls the site slopes gradually to the east toward 138"' Avenue East at gradients typically in the range of 5 percent and 1ess. The immediate southwestern corner of the site also contains an approximately 20 to 30 foot high southwest-facing slope that descends offsite to the southwest at gradients of around 20 to 40 percent. The topography on the east side of 138"' Avenue East is also defined by a series of knolls located along a northwest trending line between the southeast corner and north central portions of the eastern development area. The west side of the knolls slope gradually to the west at gradients of around 5 percent or less. To the east of the knolls, the site slopes to the east-northeast at gradients generally in the range of 5 to 10 percent. The north and south flanks of the three knolls descend from the center point of the features to the north and south at gradients of 10 percent and less. Large potions of the site consist of open pastureland that is vegetated by tall grass and localized areas containing dense growths of blackberry brambles. The immediate southwest corner of the site is vegetated with small to medium diameter trees. The site is also vegetated with localized deco�ative shrubs and plants and medium diameter trees in the vicinity of the existing residences that currently occupy portions of the site. Subsurface Subsurface conditions for the site and vicinity were evaluated by reviewing geologic maps, soil maps, and excavating fifteen (15) test pits at the approximate locations shown on Plate 2. Geologic Review Review of geologic maps indicates the site is underlain by glacial till f�om the Vashon stade of the Frasier glaciation. The till consist of a compact, unsorted mixture of clay, silt, sand, and gravel. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY ', Conner Homes F 1 ,-�<.+�� I ,_ �,. -,„„ , Review of the United States Department of Agriculture Natural Resource Conservation Service (formerly United States Soil Conservation Service) maps for King County indicates that the proposed development area is underlain by Alderwood gravelly sandy loam, 6 to 15 percent slopes. This soil has a moderate erosion hazard. Subsurface Exploration Subsurface conditions at the site were evaluated by excavating fifteen (15) test pits at the approximate locations shown on Plate 2. The test pits were excavated with a rubber-tired backhoe to a maximum depth of ten feet below grade. Our test pit logs are included as Plates A2 through A16. Please refer to the test pit logs for a detailed description of the conditions encountered at each exploration location. A description of the field exploration methods is included in Appendix A. The following is a generalized description of the subsurface conditions encountered. At our test pit locations, we typically encountered a six (6) to twelve {12) inch thick layer of topsoil and either grass or duff. The topsoil is characterized by its dark brown color, loose consistency, and the presence of roots and organic debris. The soil and vegetative layer is not suitable for support of foundations, slab-on-grade floors, or pavements. In addition, it is not suitable for use as structural fill, nor should it be mixed with material to be used as structural fill. Underlying the topsoil and vegetative layer, we generally encountered a surficial layer of loose to medium dense silty sand with gravel (Unified Soil Classification SM) over weathered to unweathered glacial till comprised of silty sand with gravel (SM). In Test Pits TP-3, TP-4, TP-5, TP-6, and TP-12 the surficial layer of silty sand and the underlying glacial till are separated by one and one-half to two and one-half feet of loose to medium dense poorly graded gravef (GP}, poorly graded gravel with silt and sand (GP-GM}, or poorly graded sand with silt and gravel (SP-SM). The weathered glacial till was generally encountered at th�ee to four and one half feet below existing grade at our test pit locations. The glacial till generally became dense and less weathered at four and one half to six feet below existing grade. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 6 Groundwater Moderate to heavy groundwater seepage was encountered at eleven (1 1) of our test pit locations at depths ranging from one to six feet below existing grade. The observed seepage is likely indicative of seasonai perched groundwater collecting above the underlying dense low-permeability glacial till encountered at our test pit locations. Based on conditions observed at our test pit locations, in our opinion, moderate to heavy, perched groundwater seepage could be encountered if grading is conducted during the wet season. The contractor should be made aware that groundwater levels are not static. There will iikely be fluctuations in the level depending on the season, amount of rainfall, surface water runoff, and other factors. Generally, the water level is higher and seepage rates are greater in the wetter winter months (typically October through May). The contractor should be prepared to control groundwater if seepage is encountered in site excavations. Laboratory Testing Laboratory tests were conducted on representative soil samples to verify or modify the field soil classifications and to evaluate the general physical properties and engineering characteristics of the soil encountered. Visual field classifications were supplemented by grain size analyses on representative soil samples. Moisture content tests were performed on all samples. The results of laboratory tests performed on specific samples are provided either at the appropriate sample depth on the individual test pit logs or on a separate data sheet contained in Appendix B. It is important to note that these test results may not accurately represent the overall in-situ soil conditions. Our geotechnical engineering recommendations are based on our interpretation of these test results and their use in guiding our engineering judgment. ECI cannot be responsible for the interpretation of these data by others. In accordance with our Standard Fee Schedule and General Conditions, the soil samples for this project will be discarded after a period of fifteen (15) days following completion of this report unless we are otherwise directed in writing. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 7 CRITICAL AREA CONSIDERATIONS A part of our study was conducted to address potential geologic hazards within the subject site as defined in Renton Municipal Code Section 4-3-050 (Critical Areas Regulations). The City of Renton identifies five different types of geologic hazards: steep slopes, landslide hazards, erosion hazards, seismic hazards, and Coal Mine Hazards. The City's criteria for those various hazard areas are defined as follows: Steep Slopes The boundaries of a regulated steep sensitive or protected slope are determined to be in the location identified on the City of Renton's Steep Slope Atlas. RMC 4-3- 050B.4.b. As noted in RMC 4-3-050B.1 .c, the City's steep slope types are: Sensitive Slopes: gradients of 25 to 40 percent Protected Slopes: gradients steeper than 40 percent I Erosion Hazard Areas I The City of Renton has two classifications of erosion hazard areas. Low Erosion Hazard (EL): Areas with soils characterized by the Natural Resource I', Conservation Service (formerly U.S. Soil Conservation Service) as having slight '� or moderate erosion potential, and that slope less than fifteen percent (15%). RMC 4-3-050B.4.d.i. High Erosion Hazard (EHI: Areas with soils characterized by the Natural Resource Conservation Service as having severe or very severe erosion potential, and that slope more steeply than fifteen percent (15%►. RMC 4-3-050B.4.d.ii. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes , . �?� n n� • �� 3�_. _ 'i Lk r'� � _ ��-� t 3 s�`�i>{7i: ��t.'t31i er,.:'s� There are four classifications Low Landslide Hazar,� /� l I• /�rt�?c �n�itl� clnnac �pcc t{�ar? fiftaan nP(!`Qr�+ 1� G,r RMC 4-3-05�B.4.c Medium Landslide Hazard ILM): Areas with slopes between fifteen percent (15%) and forty percent (40%) and underlain by soils that consist largely of sand, gravel or glacial till. RMC 4-3-050B.4.c.ii. Hi_qh Landslide Hazards (LH): Areas with slopes greater than forty percent �40%), and areas with slopes between fifteen (15%) and forty percent (40%) and underlain by soils consisting largely of silt and clay. RMC 4-3-050B.4.c.iii. Very High Landslide Hazards (LV): Areas of known mappable landslide deposits. RMC 4-3-050B.4.c.iv. Seismic Hazards I Seismic hazards are classified under the two following categories: Low Seismic Hazard (SL�: Areas underlain by dense soils or bedrock. These soils generally have site coefficients of types S1 or S2, as defined in the Uniform Building Code. RMC 4-3-050B.4.e.i. Hiqh Seismic Hazard (SH): Areas underlain by soft or loose, saturated soils. These soils generally have site coefficients of types S3 or S4, as defined in the Uniform Building Code. RMC 4-3-050B.4.e.ii. Coal Mine Hazards The City of Renton has three categories of coal mine hazards: low, medium, and high. Low Coal Mine Hazards (CLJ: Areas with no known mine workings and no predicted subsidence. While no mines are known in these areas, undocumented mining is known to have occu�red. RMC 4-3-050B.4.f.i. Earth Consultants, Inc. . GEOTECHNICAL ENGINEERING STUDY , Conner Homes E-10988 ' January 28, 2004 Page 9 ' Medium Coal Mine Hazards CM : Areas where mine �vorkin r r n I ( ) gs a e deepe tha two hundred feet (200') for steeply dipping seams, or deeper than fifteen (15) I, times the thickness of the seam or workings for gently dipping seams These ! areas may be affected by subsidence. RMC 4-3-050B.4.f.ii. I�I Hiqh Coal Mine Hazard (CH): Areas with abandoned and improperly sealed mine I openings and areas underlain by mine workings shallower than two hundred feet (200'j in depth of steeply dipping seams, or shallower than fifteen (15) times the thickness of the seam or workings for gently dipping seams. These areas m be affected by collapse or other subsidence. RMC 4-3-0506.4.f.i. Geologic Hazard Revie II Portions of the site appear to meet the City of Renton's criteria for steep slope, �I erosion, and landslide hazards. Potentially liquefiable soils were not encountered at our exploration locations; therefore the site does not meet the criteria for seismic hazard areas. Based on review of historical coalmine records, the site does not meet the requirements for coal mine hazards. The following sections of our study specifically address the steep slope, erosion, landslide, seismic, and coal mine hazard areas. Steep Slopes Most of the site consists of gently rolling topography, with slope gradients of less than 15 percent. However, in the southwest corne� of the site, in Tract H and west of Lot 60 shown on Plate 2, Test Pit Location Plan, is a fifteen (15) to thirty (30) foot high descending slope. The slope has a gradient of 30 to 40 percent. As noted above, the City of Renton designates two classifications for slopes with gradients of 25 percent or more. These areas are defined as Sensitive Slopes (25 to 40 percent) and Protected Slopes (greater than 40 percent). The steep slope area in the southwest corner of the site meets the criteria of Sensitive Slopes and Protected Slopes. No development is planned within the Sensitive and Protected Slope areas. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 10 Erosion Hazard Areas The soils underlying the site consist of Alderwood gravelly sandy loam, 6 to � i. slopes. This soil has a moderate erosion potential and meets the city of Renton's classification of Low Erosion Hazard (RMC 4-3-050B.4.d.i). The localized steep slope area in the southwest portion of the site is steeper than 15 percent, as such, the southwest slope would be is classified a High Erosion Hazard under the City of Renton's criteria (RMC 4-3-050B.4.d.ii�. Erosion in the proposed development area will need to be controlled using best management practices. Our test pits indicate that the soils that should be encountered during construction will primarily consist of fine-grained silt and silty sand. This soil is susceptible to erosion due to sheet flow. The erosion control plan should include measures for reducing concentrated surface runoff and protecting disturbed or exposed surfaces by mulching and revegetation. The temporary erosion and sedimentation control plan should include the following: • Where practical, maintain vegetation buffers around cleared areas; • Cover exposed soil stockpiles; • Hydroseed or place straw mulch in areas where grading is completed; • Divert water away from the top of slopes; • Use silt fences and straw bales around the lower portions of the site perimeter; and • Coordinate clearing, excavation and erosion control to reduce exposed areas. The erosion control measures should be reviewed on a regular basis to verify they are functioning as intended. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-1 G988 ,?an�tar�y ?_8 20�4 �'��ca�� ? ; Landslide Hazard Areas The localized steeply sloping area in the southwest portion has a slope gradient excess of 40 percent and meets the City of Renton's landslide hazard classification for a High Landslide Hazard (RMC 4-3-050B.4.c.iii). As part of our field exploration, we traversed the southwest slope area to observe indications of past instability and potential future instability. During our reconnaissance, we did not observe any indications of shallow debris flow failures, or signs of deep-seated or global instability. However, based on our experience with similar projects, the loose to medium dense granular soils that underlie the site are susceptible to erosion and shallow debris flows if surface and subsurface groundwater are not controlled during and after construction. Debris flow failures are relatively common on the steep slopes comprising the perimeters of the glacial drift uplands in the Puget Sound Basin. When the loose, surficial soils become saturated during periods of heavy precipitation, irrigation, or by uncontrolled surface water they can fail along a contact with underlying soils with a lower permeability. These failures typically involve the upper three to four feet of the slope face and will comprise several tens of cubic yards of soil and vegetation. The result of these shallow failures is the slow inland migration of the top of slope and the deposition of a fan of colluvium at the toe of the slope. During our reconnaissance, we also observed that several of the small diameter trees growing on the slope have curved trunks. The curvature is consistent with deformation initiated by shallow creep of surficial soils, which is a normal slope process. The remaining large trees located in the western portion of the site do not appear to be affected by the creep. The observed creep is likely occurring within a three to five foot thick zone of loose surficial material. The curvature observed is not indicative of deep- seated instability. In our opinion, the observed creep should not be affected by future development, nor should the gradual creep adversely impact the proposed development provided site drainage is controlled. Construction Setbacks The building setback should be based on physical slope characteristics Isuch as slope height, slope inclination, soil type, surface water drainage and hydrology) along with the intended life of the structure. Based on the results of our reconnaissance, exploration, and engineering analyses, a minimum building setback of twenty-five (25) feet from the top of the steep slope area in the southwest portion of the site should be maintained. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E 109�8 January 28, 2004 Page 12 Seismic Hazard Areas The soils encountered at our test pit locations primarily consist of silty sand and sili, range from loose to dense, and do not contain an established groundwater table. In our opinion, these soils would not be susceptible to liquefaction. In accordance with the City of Renton's classification system, the site meets the criteria for a Low Seismic Hazard (RMC 4-3-050B.4.e.i). An additional discussion of the seismic hazards is provided in the following Seismic Design Considerations section of this study. Coal Mine Hazards Portions of Renton contain abandoned coalmines that can adversely impact a site. As part of ou� study, we reviewed information in our library and files and reviewed DNR coal mine records for information pertaining to historic coal mining operations in the vicinity of the site. During our field exploration, we did not observe any surface o� subsurface indications of coal mining activity, such as mine tailing piles, abandoned mine openings, or abandoned mining equipment, all of which are typically found near coal mine operations. As part of our study, we also reviewed the Washington State Coal Mine Map Collection: A Catalog, Index, and Users Guide, Open File Report 94-7, prepared by the Washington Division of Geology and Earth Resources, dated June 1994. Based on the results of our file review, in our opinion, the site is not underlain by coalmine workings and has a Low Coal Mine Hazard designation (RMC 4-3-050B.4.f.ii). DISCUSSION AND RECOMMENDATIONS General Based on the results of flur study, in our opinion, the site can be developed generally as planned, provided the recommendations contained in this report are followed. Building support can be provided using conventional spread and continuous footing foundation systems bearing on competent native soil or on structural fill used to modify existing site grades. Slab-on-grade floors may be similarly supported. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 , January 28, 2004 Page 13 'i The site is underlain by up to four and one half feet of loose native granular soils. If very loose to loose existing fill or native soil is encountered at construction subgrade elevation, it should either be compacted in-place to the requirements of structural fill or it should be overexcavated and replaced with structural fill. This report has been prepared for specific application to this project only and in a manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under simila� conditions in this area for the exclusive use of Conner Homes and their representatives. No warranty, expressed or implied, is made. This report, in its entirety, should be included in the project contract documents for the information of the contractor. Site Preparation and General Earthwork The building and roadway areas to receive structural fill should be stripped and cleared of surface vegetation, organic matter, and other deleterious material. Based on the thickness of the topsoil and vegetative cover encountered in our test pits, a stripping depth of approximately 6 to 12 inches for most of the site with localized areas as deep as 18 inches should be anticipated. The actual stripping depth should be based on field observation at the time of construction. Root balls from vines, brush, and trees should be grubbed out to remove roots greater than about one-inch in diameter. The depth of excavation to remove root balls could exceed two and one half feet below the existing ground surface. Depending on the grubbing methods used, disturbance and loosening of the subgrade could occur during site grubbing. Soil disturbed during grubbing operations should be compacted in-place to the requirements of structural fill. Stripped materials should not be mixed with materials to be used as structural fill. The stripped soil materials may be "wasted" on site in non-structural landscaping areas or they may be exported off site. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 14 Following the stripping operation and excavations necessary to achieve construction subgrade elevations, an ECI representative should observe the ground surface where structural fill, foundations, or slabs are to be placed. Soil in loose o� soft areas, if recompacted and still excessively yielding, should be overexcavated and replaced with structural fill. The optional use of a geotextile fabric placed directly on the overexcavated surface may help to bridge unstable areas. ECI can provide recommendations for geotextiles, if necessary. Structural fill is defined as compacted fill placed under buildings, roadways, slabs, pavements, or other load-bearing areas. Structural fill unde� floor slabs and footings should be placed in horizontal lifts not exceeding twelve (12) inches in loose thickness and compacted to a minimum of 90 percent of its laboratory maximum dry density determined in accordance with ASTM Test Designation D-1557-91 {Modified Proctor). The fill materials should be placed at or near their optimum moisture content. Structural fill in roadway and public right-of-way areas should be compacted in accordance with the City of Renton's requirements. Renton requires structural fill in roads and right-of-way areas be compacted to 95 percent of maximum density in accordance with ASTM Test Designation D-1557 (Modified Proctor). Based on the results of our laboratory tests, the on-site soils at the time of our exploration appeared to be near their optimum moisture content and should be suitable for use as structural fill. However, laboratory testing indicates the site soils have between 1 and 27 percent fines passing the No. 200 sieve. Soil with fines in excess of around 5 percent will degrade if exposed to excessive moisture, and compaction and grading will be difficult if the soil moisture increases significantly above its optimum level. If the site soils are exposed to excessive moisture and cannot be adequately compacted, then it may be necessary to import a soil that can be compacted. During dry weather, non-organic, compactable granular soil with a maximum grain size of four inches can be used. Fill for use during wet weather should consist of a fairly well graded granular material having a maximum grain size of four inches and no more than 5 percent fines passing the No. 200 sieve based on the minus 3/4-inch fraction. A contingency in the earthwork budget should be included for the possibility of importing a material meeting this specification. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 Jar�uar�y� 28, 200� Page 1 5 SloPe Fiil Placement In our opinion, the placement of fil� ��: , . ��:�.�r � „�r y j�� _� �� ,�_=G t '.�;I�. � _,��.-.��.��r slope gra��Ant avrneric ��, n�r��. . ' the slope This process should consist of excavating a keyway at the toe of the planned fill. T: keyway should have a width of about six to eight feet and a depth of at least two fe into medium dense to dense native soil. The slope above the keyway should then be c into a series of horizontal to slightly inward sloping benches. Typically, the benches are excavated with a small bulldozer as the fill is brought up. The width of the benches will vary with the gradient of the slope, usually the gentler the slope, the wider the benches. Plate 3, Slope Fill Placement shows a schematic diagram of the keyway and benches. Foundations Based on the results of our study and provided our recommendations are followed, in our opinion, the future single-family residences can be supported on conventional spread and continuous footing foundation systems bearing on competent native soil or on structural fill used to modify site grades. If loose fill or native soil is encountered at construction subgrade elevations, it will be necessary to either compact the soils to the requirements of structural fill or to overexcavate the loose soils and replace them with a minimum of twelve (12) inches of st�uctural fill. Exterio� foundation elements should be placed at a minimum depth of eighteen (18) inches below fina! exterior grade. Interior spread foundations can be placed at a minimum depth of twelve (12) inches below the top of slab, except in unheated areas, where interior foundation elements should be founded at a minimum depth of eighteen (18) inches. Continuous and individual spread footings should have minimum widths of sixteen (16) and eighteen (18) inches, respectively. Earth Consultants, Inc. � GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 16 l�Jith foundation support obtained as described, for design, an allo�^✓able soil bearing capacity of two thousand five hundred (2,500) psf can be used for competent native soils, native soil compacted to the requirements of structural fill, or for newly placed structural fill used to modify site grades. Loading of this magnitude would be provided with a theoretical factor-of-safety in excess of three against actual shear failure. For short-term dynamic loa��n^ ('r,r�rlitinnc q nno_+I1;�� ;,,�r�.,�.-, ;., +h� .,�,,,,.� ,��,,�,.,�,�„ h,,.,,�,, capacities can be used With structural loading as expected, total settlement of tess than one inch is anticipated with differential movement of less than one-half inch. Most of the anticipated settlement should occur during construction as dead loads are applied. Horizontal loads can be resisted by friction between the base of the foundation and the supporting soil and by passive soil pressure acting on the face of the buried portion of the foundation. For the latter, the foundation must be poured "neat" against the competent native soils or backfilled with structural fill. For frictional capacity, a coefficient of 0.35 can be used. For passive earth pressure, the available resistance can be computed using an equivalent fluid pressure of three hundred fifty (350) pounds per cubic foot (pcf). These lateral resistance values are allowable values, a factor-of-safety of 1 .5 has been included. As movement of the foundation element is required to mobilize full passive resistance, the passive resistance should be neglected if such movement is not acceptable. Footing excavations should be observed by a representative of ECI, prior to placing forms or rebar, to verify that conditions are as anticipated in this report. Slab-on-Grade Floors Slab-on-grade floors can be supported on competent native soil, native soil compacted in- pface to the requirements of structural fill, or on structural fill used to modify site grades. Subgrade soils that are loose or disturbed during construction should either be compacted in-place to the requirements of structural fill or overexcavated and replaced with structural fill. Earth Consultants, Inc. . GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 17 Slabs should be provided with a capillary break consisting of a minimum four inches of free-draining sand or gravel. In areas where slab moisture is undesirable, a vapor barrier such as a 6-mil plastic membrane should be placed beneath the slab. Two inches of damp sand may be placed over the membrane for protection during construction and to aid in curing of the concrete. Retaining Walls Retaining walls should be designed to resist the lateral loads imposed by the retained soils. Walls that are designed to yield can be designed to resist the lateral earth pressures imposed by an equivalent fluid with a unit weight of thirty-five (35) pcf. If walls are to be restrained at the top from free movement, the equivalent fluid weight should be increased to fifty (50) pcf. These values are based on horizontal backfill and that surcharges due to backfill slopes, hydrostatic pressures, traffic, structural loads or other surcharge loads will not act on the wall. If such surcharges are to apply, they should be added to the above design lateral pressure. The passive pressure, friction coefficient, and allowable bearing capacity previously provided in the Foundations section of this study are applicable to the retaining wall design. To reduce the potential for hyd�ostatic forces building up behind the walls, free- standing retaining walls and foundation walls should be backfilled with free-draining material extending at least eighteen (18) inches behind the wall. The free-draining backfill should consist of pea gravel or washed rock with a fines content of less than 5 percent, based on the minus 3/4-inch fraction. A rigid, four-inch diameter, schedule 40, perforated PVC or SDR 35 drainpipe should be placed at the base of the wall, and should be surrounded by a minimum of one cubic foot per lineal foot with three-eighths inch pea gravel. The pipe should be placed with the perforations in the down position. ', The remainder of the backfill should c�nsist of structural fill. A typical retaining wall , drainage and backfill detail is provided on Plate 4. ! Seismic Design Considerations The Puget Lowland is classified as a Seismic Zone 3 in the 1997 Uniform Building Code (UBC). Earthquakes occur in the Puget Lowland with regularity, however, the majority of these events are of such low magnitude they are not felt without instruments. Large earthquakes do occur, as indicated by the 1949, 7.2 magnitude earthquake in the Olympia area, the 1965, 6.5 magnitude earthquake in the Midway area, and the 2001 , 6.8 magnitude Nisqually earthquake. Earth Consultants, Inc. �� GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 18 There are three potential geologic hazards associated �°�ith a strong motion seisr��ic e•:�ent at this site: caroun�_i r�._iF_t�:r�� I�,�,._��`a��ti;_�� :n�� arr�u��r� ��i� t �� r��E.�onse. Ground Ruptur� The strongest earthquakes in the Puget Lowland are widespread, subcrustal event ranging in depth from thirty f 30) to fifty-five (55) miles. Surface faulting from these de� events has not been documented to date. Therefore, it is our opinion, that the risk ground rupture at this site during a strong motion seismic event is negliqible. Liq: Liqu�,u��„ ,.� U ,�;,�„�;,;�:;��; �;, ��; �;�„ ��,�� .: �� ;a� JLI��y�� : � �;��u� �� itime during an earthquake. Groundshaking of sufficient duration results in the loss of grain to grain contact and rapid increase in pore water pressure, causing the soil to behave as a fluid. To have a potential for liquefaction, a soil must be cohesionless with a grain size distribution of a specified range (generally sand and silt►; it must be loose; it must be below the groundwater table; and it must be subject to sufficient magnitude and duration of groundshaking. The effects of liquefaction may be large total and/or differential settlement for structures founded in the liquefying soils. In our opinion, the potential for liquefaction induced settlement of the soils encountered at this site should be negligible p�ovided the recommendations contained in our study are followed. This conclusion is based on the absence of a shallow groundwater table in the immediate vicinity of the proposed residential lots. Ground Motion Response The 1997 UBC seismic design section provides a series of soil types that are used as a basis for seismic design of structures. Based on the encountered soil conditions, it is our opinion that soil type Sc, Very Dense Soil and Soft Rock, from Table 16-J should be used for design. � Earth Consultants, Inc. , GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 19 Excavations and Slopes The following info�mation is provided solely as a service to our client. Under no ci�cumstances should this information be interpreted to mean that ECI is assuming responsibility for construction site safety or the contractor's activities, such responsibility is not being implied and should not be inferred. In no case should excavation slopes be greater than the limits specified in local, state (WISHA), and Federal (OSHA) safety regulations. Based on the information obtained from the subsurface exploration, the loose to medium dense soils encountered in the upper portion of the test pit locations would be classified as Type C by OSHA/WISHA. Temporary cuts greater than four feet in height in Type C soils should be sloped at an inclination of 1 .5H:1 V (Horizontal:Vertical). The underlying dense to very dense glacial till encountered at our test pit locations would be classified as Type A by OSHA/WISHA. Temporary cuts greater than four feet in height in Type A soils should be sloped at an inclination of 0.75H:1 V. Where groundwater seepage is encountered the saturated to waterbearing soils should be treated as a Type C soil and should be cut no steeper than 1 .5H:1 V. If slopes of this inclination, or flatter, cannot be constructed, temporary shoring may be necessary. Shoring will help protect against slope or excavation collapse, and will provide protection to workers in the excavation. If temporary shoring is required, we will be available to provide shoring design criteria. Permanent cut and fill slopes should be inclined no steeper than 2H:1 V. Cut slopes should be observed by ECI during excavation to verify that conditions are as anticipated. Supplementary recommendations can then be developed, if needed, to improve stability, including flattening of slopes or installation of surface or subsurface drains. Permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and to improve stability of the surficial layer of soil. I Earih Consultants, Inc. , GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 20 Site Drainage Moderate to heavy groundwater seepage was encountered at eleven (1 1) of our test pit locations at depths ranging from one to six feet below existing grade. The observed seepage is likely indicative of seasonal perched groundwater collecting above the underlying dense to very dense low-permeability glacial till encountered at each of our test pit locations. If seepage is encountered during construction, the bottom of the excavation should be sloped to one or more shallow sump pits. The collected water can then be pumped from these pits to a positive and permanent dischar e. De endin on the ma nitude of such 9 P 9 9 seepage, it may also be necessary to interconnect the sump pits by a system of connector trenches. The appropriate locations of subsurface drains, if needed, should be established during grading operations by ECI's representative at which time the seepage areas, if present, may be more clearly defined. During construction, the site must be graded such that surface water is directed away from construction areas and the steep slope area located in the immediate southwestern corner of the site. Water must not be allowed to stand in areas where foundations, slabs, or pavements are to be constructed. Loose surfaces should be sealed by compacting the surface to reduce the potential for moisture infiltration into the soils. Final site grades must allow for drainage away from the future residences and the steep slope area in the southwestern corner of the site. The ground should be sloped at a gradient of 3 percent for a distance of at least ten feet away from the residences. Footing drains should be installed around the perimeter of the residences at or just below the invert of the footing, with a gradient sufficient to initiate flow. A typical detail is provided on Plate 5. Under no circumstances should roof downspout drain lines be connected to the footing drain system. Roof downspouts must be separately tightlined to discharge. Cleanouts should be installed at strategic locations to allow for periodic maintenance of the footing drain and downspout tightline systems. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 21 Utility Support and Backfill The site soils should generally provide adequate support for utilities. Where loose soils or unstable conditions are encountered, remedial measures such as overexcavating soft soils or compacting subgrade soils exposed in the trench bottom may be required. In addition, at our test pit locations we encountered interbeds of cohesionless soils that caved in the loose to medium dense cohesionless soils. Caving of trench walls should be anticipated in trench excavations. Utility trench backfill is a primary concern in reducing the potential for settlement along utility alignments, particularly in pavement areas. It is important that each section of utility line is adequately supported in the bedding material. The material should be hand tamped to provide support around the pipe haunches. Fill should be carefully placed and hand tamped to about 12 inches above the crown of the pipe before heavy compaction equipment is brought into use. The remainder of the trench backfill should be placed in lifts having a loose thickness of less than twelve (12) inches. Pavement Areas The adequacy of site pavements is related in part to the condition of the underlying ' subgrade. To provide a properly prepared subgrade for pavements, the subgrade should be treated and prepared as described in the Site Preparation and General Earthwork ' section of this report. ', It is possible that some localized areas of soft, wet or unstable subgrade may still exist �I after this process. Therefore, a greater thickness of structural fill or crushed rock may be �� needed to stabilize these localized areas. The following pavement section for lightly-loaded areas can be used: • Two inches of asphalt concrete (AC) over four inches of crushed rock base (CRB) material, or • Two inches of AC over three inches of asphalt treated base (ATB) material. We will be pleased to assist in developing appropriate pavement sections for heavy traffic zones, if needed. Earth Co�sultants, Inc. GEOTECHNICAL ENGINEERING STUDY Conner Homes E-10988 January 28, 2004 Page 22 Pavement materials should conform to WSDOT specifications. The use of a Class B asphalt mix is suggested. LIMITATIONS Our recommendations and conclusions are based on the observed site materials, selective laboratory testing, engineering analyses, the design information provided us, and our experience and engineering judgment. The conclusions and recommendations are professional opinions derived in a manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. No warranty is expressed or implied. The recommendations submitted in this report are based on the data obtained from the test pits. Soil and groundwater conditions between test pits may vary from those encountered. The nature and extent of variations between our exploratory locations may not become evident until construction. If variations do appear, ECI should be requested to reevaluate the recommendations of this report and to modify or verify them in writing prior to proceeding with the construction. Additional Services As the geotechnical engineer of record, ECI should be retained to perform a general review of the final design and specifications to verify the earthwork and foundation recommendations have been properly interpreted and implemented in the design and in the construction specifications. ECI should also be retained to provide geotechnical engineering services during construction. This is to observe compliance with the design concepts, specifications or recommendations and to facilitate design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. 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F ... . . �grq-"F "'_{"—.F. _' -- � -� -- : a� ----- ------- � � � � � Earth Consultants, Inc. �- �- - ��Geotechnicai Engmeering,Geology.Environmental Sciences Referenee: �� ConstrucRon Testing&ICBO;W,1B0Inspeclion Serv�ices � King County ' � Map 656 Vicinity Map ! By Thomas Brothers Maps Laurelhurst Dated 2004 King County, Washington NOTE: This plate may contain areas of color. ECI cannot be responsible for any subsequent Drwn. GLS Date Jan. 2004 Proj. No. 10988 misinterpretation of the information resulting Checked SDD Date 1/27/04 Plate 1 from black& white reproductions of this plate. __ _� ___., .._ __ _, �.. _.. _� _ _. -- i_ _- _ __ _---�- -. _ --- - - - , _ ._ _ ' .� i � i _ � _ i i 1 � � _ ._ _ � _ � �a , ' -.: � •;- , '' , g5 , i : _ _F � - - - -- -- -- -- ' �¢ � 57 ` 56 � _ � �-. � 53 � + ' ' i I ! , I ( ; TP-11I , ;, I ! 1 -�-� �� ; cxrcir`ng l-;'�, �_ �- - - — - - -; � i �TP-9 � -- - - —`.� , -�— - -i --- - : _ ; v;L _� _ _ 1■- __ �___ - --� � , � , � - --, TP� g� F ; � ;, �-, : _. � � � � � ° � i �` � �� - - -� f =�� a� ' �.s ` - -� f � ! � � i 62 � 1 -I - -- I v' � / �,�� , , ; : _�- '_— _ _ _' ;— - = -�- -`- —, _--- -_ ___ __ _ _ , _` —_� _;__�TP-12 ; i Approximate Scale �� I � � �o _I TP-8 ,,. ,` � _! i � 1c ' (_ _�_ r_ - � — -�, .,, ; c2 � ' __ 0 75 150 300it. £ f— �_ i ;t I i� � s� � �n 3; ! -L -�- k .zc, r— - - ; ' 4 ; ' s � ', � ; � ' I i � I �t � -- - - -- � - - -�- - - , � ; �P110 � � I � � ' � � � - - - - � -- ' --�- - — r � ; � �2 , � ° �r � i � - �� 1 ; ( �� F- -- - -- - - - �� I ' ' � i �ry i } L � � i3 � ' ' �.s , { '� i `"�C� ` � ( � ` , :�. LEGEND - - -- �- - - -� - - -}- - - �-- -- - t, ! ' '� � -�- - --- — ' -.— _-�- - - _ , , � � — - � � � , �TP_� _ _ _ _ __ _ _ TP-1_� _ __ - , TP-1-�- Approximate Location of '-- - _ _ _._ • ; . ; � ; i � ECI Test Pit, Proj. No. � � _�- ! =s � .,; . -s � ,� 2� � i - � ' �� E-10988, Dec. 2003 � � ,� � i E � i i ; . � � �_ �_ E - � I �� i � �-- - - - - - � � i I i � � � � ! .. _ � .� _ _, i_ � � _ .� � ! � _ ! � �� y - - - es _ _ �. _ _ .� _ .v _ _ �_ � _�� , SubjectSite _� �,_��—�, _�_ r��.�,��?(1 S_ �_ :±�� _ �- �___- __ _. __ _ _. __ _ .____ __ � _ _ _ _ �, — — — _ _ \ .... � _ : i i ' ( ' i i P�-�-- - -� - -- ' � `�` i- ? � Proposed Lot Number ; � �, � ; , ; 's � � ; _. � _, i �g � �Q I � � 3� � ?:2 � .?,� �+.� � 4 � 36 ( 5G , I �j i � s �� ' � I TP-15 � � � � � � . � � '— - - --- - - —� i € ! � '- - . '' - -� --- ; 5 � � � � ; : __ . � -i! - % � - - - - - �-, i �� :-- -- ! � , ; _ � ` 2� __ _, - - __ _ - - - - - -- - -- - - - -- -, - -- - ; -- - --E _ ` ` i : �� 3$ � Y8 � � t t i i n.. __ ..� -.. � � �2 � �1 � i� � C .�u �g - i � . i ! ' I --- - � ' F s� i { i o '. -� -- - - --r- - - -- ; , � ' ` ' -- � t , �— _ _� � � ; 1 � f ; f- ' i � � �7c; 7� � i I .. - _ _, , -' — -I 4 -' i i . _ l , �. i f � t � � , . . � i _ _y _ _ _ _ �- i,`� i -� ?`} � � � � �'- - - -' ITp-1- - - - � �� aco � I � �. + ; ;�: ■— � .:f. ! I I � .�_ _ __ ._ _ __: .<. _.-m_ a _ �� _ .� _ - _ � i = ;� i I , � T � _ � _ _ _ _ _ NOTE: This plate may contain areas of color. � q I r� � i f ,` �� i � - - � , � � i= - - �-- - - - ; , � � � ECI cannot be responsible for any subsequent __ ; _ ,''� 7� � �. � ,�� f � ; _�` ; ' T,-1�2� � { misinterpretation of the information resulting ; , \ � _ _, � _ ; ( . � ; from black& white reproductions of this plate. i_ , ; � �' ; � � Tract i.1 -- - i —j+-- � _� ( � ! I � � - -' - , -- - - - - _ � � , i �''? i� � -� i �i i � � �TP-5 �� ' �<" ,�3 �� _ .._, � , � : , � - ` & G, � � `�� I i �. ._- -- -irP-2 � � Earth Consultants, inc. �I ; • J � � I � -I-J 1^ Geotechn}cal Engineenng Geology,Environmental Sciences : � ; �; -- , � � /" �� .___� TP-4..' � S Consfructlon"T�stlng&ICBO!W.qBO lnspectlon Servfces : -� -�,� _..� _ ��'-- - - -•�� ,.� - _ � ---- __.- -. l ' I I 1 F , `! \ � = � - - � _ _ _ e i � i __ -' / ; ° , , z : s -� 4 , ; � �-- -;- — - - --�-_�TP-- - ;-- - - --i , Test Pit Location Plan , , � i i � 't r;��r� . � � � i ; f .. ) ' . I � � `; -' ' ,�; ss �s � �; � � �. �:� �� , �� -�� 3 � � Laurelhurst i � ; - - ' - - - — - _— - - , ! � , i , r � TP- . rr4�rH � King County, Washington i . _. _. .__ .� _ _ �. _ _ � _ .� _` , - _ � _ _ L._. _ _ ..� _ m � _ � _ � _�... � _. _. _�. � __� �, _. ,..�� Drvvn. GLS Date Jan. 2004 Proj. No. 10988 Checked SDD Date 1/27/04 Plate 2 Final Slope Gradient - - •'�� (See Text) •`:?:,. ..�.... H ,;::•.===::==•' �—i I i=1 I I . �I i I=I I I ::ti::=�.. 111= v I� :•r7•`:�.i!:.. � �'��. I '',:y,�'.:c��—�� 6cisting =�`�:;��: - =I I I I I I G rade � Existing �='��='= _ Grade ::r;'•,:::;`.';�:�r;_,: — :-`::ti::'-::'..,':II1=111= ••�;�;;�:'�'✓�� =1 I I Typical 'Bench" :_,::;�^::;;��'j: ��= 4 feet minimum 1 I 1=1 I 1= — width 11� � III Ii1-111 "Key" 111= III STANDARD NOTES LESaEdQ • Slope should be stripped of topsoil Free draining,organic free,granular material and unsuitable materials prior to ?'�f; with a maximum size of 3 inches,containing excavating key way or benches. no more than 5 percent fines(silt and clay size particles passing the No.200 mesh sieve)or • Benches will typically be equal to a other material approved by Geotechnical dozer blade width, approximately Engineer. 8 feet, but a minimum of 4 feet. Key Way Fill is same as Stn�ctural Fill described • Final Sbpe gradient should be '�•�' above. Key Way should minimum 2 feet deep i _ . _ (Horizontal : Vertical). and 6 feet wide, extending the full length of the slope face. � • Fnal Slope face should be densi�ed I by over-building with compacted fill ----- Approximate original grade. and trimming back to shape or by compaction with dozer or roller. • Planting or Hydroseeding slope face SCHEMATIC ONLY- NOT TO SCALE with a rapid growth deep rooted NOT A CONSTRUCTION DRAWING vegetative mat will reduce erosion potential of slope area. • Use of pegged-in-place jute matting or �s� Earth Consultants, 117C. �-� geotechnical fabric will help maintain the ��.� Geo�echnical Enguieers,c,eotogisrs a Environmental Scieruisfs seed and mu�h in place until the root `°"5"""ro"Tes""g�"Bo'w"��S�"b"�`""es system has an opportunity to gertninate. SLOPE FILL PLACEMENT • Structural Fill should be placed in thin loose Laurelhurst lifts not exceeding 10 inches in thiclmess. KInQ COUnty, Washington Each lift should be compacted to no less than the degree specified in the site preparation and Earth Work Section of this ��• GLS Date Jan.2004 Proj. No. 10988 report. No additional lift should be placed �� SDD Date 1/29/04 Plate 3 until compaction is achieved. Free Draining 18 inches min. ovO� Backfill - 111=111=111= I o° ° =111 Iil Min 2"Dia. o°o° �c 12 inches �, '•'' :��'; II ';.=':�`~��=�'�.:.;::�.;:;��:�=~ III I� 1 ° o 0 0' ;• {: •:' '_: Weep Hole o 0 0 � :::�:��=::�:=:�. ::.v�:=: =:•:•::: :;: : �o�o o� e �•o� U O Ov o00 0•.~"��'��• � O �p� � O �pa�p °o O o� O : 'O'. . 0 0 o a o . "�O o � C O O° � a o�0o flo0 .��.'j • 00 c1 . .p�. � ro p � o o � o o��O �•o,o :.Q . Min. 6" $oo°oo� 1"Drain o oo�oo ° aoo �o'o o. ti•:•o�;• 0 ��000 o ROCk o� o`a 0 000000 ::�: ;:: II1=111 0,o0 0� o0 00 0 0 � o o •- Excavated Slope III - o, oa o00 o:t :o.. 000000° o00 0 .• . �o 00 O o 0�Oo • ; � o� �� 000 o �.0.�,'0• 'o �O°�O ��Doo�o �rp'��. 00° � � 0�000000 �� ;',c VNEEP HOLE DETAIL °°o ° � °a��°O° ':�o' ooa�Op ° 000 �000:-- 0 00 o°o 0 000�a oo '. Perforated Pipe 111=111�11 0° °o� o 0 0 0� ° •°=�� Wrapped with 1 foot min. °o"_�' ''•o FiRer Fabric � o � 1 foot min. Compacted Subgrade ^,zTANDARD NOTES 1 F�FNQ 1) Free Draining backfill should consist of :' Surface Seal; Native Soil or other Low granular soil having no more than 5 ':� Permeability Material percent passing the#200 sieve and no particles greater than 4 inches in o0 o aoo Free Draining Backfill diameter. The percentage of particles passing the#4 sieve should be between o.:. 25 and 75 percent. •�:`-:--_o Structural Fill com acted to 90 ercent �..�•a..: P P o ' relative compacfion 2) Structural backfill should be free of o �oa�° organics,clayey soils, debris and other oaop o�o 0 1 inch Drain Rock deleterious materials. It should be ° °' ° placed at or near the optimum moisture content. SCHEMATIC ONLY- NOT TO SCALE 3) Where weep holes are utilized,surround NOT A CONSTRUCTION DRAWING each weep hole with 3 cubic feet of 1 inch ; drain rock. Maximum horizontal spacing i i of weep holes should be 6 feet. Eartrl COI�ISUI�aI�1tS, lnc. �� Georechnical Eng�neers,Geobgists t4 Environmental Scientists 4) Drain pipe; perforated or slotted rigid ConstructionTesling31C60!WA601nspeclionServices PVC pipe laid with perforations or slots facing down;tight jointed; with a positive RETAINING WALL DRAINAGE AND BACKFILL gradient. Do not use flexible corrugated Laurelhurst plastic pipe. Drain line should be bedded on and surround with free draining 1 inch King County, Washington drain rock.The drain rock may be encapsulated with a geotechnical drainage Drwn. GLS Date Jan. 2004 Proj. No. 10988 fabric at the engineers discretion. Checked SDD Date 1/29/04 Plate 4 i I ' �__!Slope To Drain _ . ...•� � :;: - :ti: .;;: i'�. .1� 6 inch min. �f� •�� t-� �:::;' .•��r:;=� •`'�`o; =:o�;o'�`•-'..'-a��•'�o;,;'o�•.";-o^�-�o�a ..000 o�a o o°o� °o��a o 0 0�o� °0�� o 0 0 0° o�� o00 ° a�oo�° o00 ° 00 0�� o00 � 18inch O000�p�0000� Oo o��p000p �Oo�� 000 0 0 0 000 0 0o min. �p °OO o° O �Qo�p ��O o° O �po�p �aD o o�po Oa0 O° � 0 a�0a�0c0�O° � � 0�00�� I � p o o��o Q a o 0 0 0 0�ro o a � � p o o� � o�� o°�o oo�Op a o°� o�o pa�Op o o�� o� j O o ap °� O 00� o �p �� O 00�o 4 inch min. � � o 0 0 0 � e o 0 o e o ao 00 op p a o0 00 00 op o �oo oa Diameter o � o 0 0 0�,� o,o ° o 0 o i i Perforated Pipe oo�o 0 0 0 o 0000°o�o 0 o I W rapped in Drainage �° ° °�°°o °°° °° ° °� ' o � Fabric 'oo° � ° �°�oo°b° o , o 00 0 I O� O�O D�o . ° o O `► O � n I 2 inch min. ! 2 inch min./4 inch max. ; i 12 inch � min. LES'aE�2 � Surface seal;native soil or other SCHEMATIC ONLY- NOT TO SCALE bw permeability material. NOT A CONSTRUCTION DRAWING 0 °°� °�° 1"Drain Rock 000 0 00 � Drain pipe; perforated or slotted rigid � O PVC pipe laid with perforations or Earth Consultants, �I1C. slots facing down;tight jointed;with a '�� Geaechnical Engineers Geobgists 6 Envuonmenral Scienlists Cons�ruciion Testing&ICBO/WABO InspeUion Services positive gradient. Do not use flexible � corrugated plastic pipe. Do not tie ( building downspout drains into footing TYPICAL FOOTING SUBDRAIN DETAIL lines. Wrap with Mirafi 140 Flter Fabric L8U1'elhUt'St or equivalent. King Courtty, Washington Drvm. GLS Date Jan.2004 Proj. No. 10988 � � Checked SDD Date 1/29l04 Plate 5 i � � APPENDIX A FIELD EXPLORATION E-10988 Our test pit exploration was performed on December 31 , 2003. The subsurface conditions at the site were explored by excavating fifteen (15) test pits to a maximum depth of ten feet below existing grade. The test pits were excavated by Northwest Excavating, subcontracted to ECI, using a rubber-tired backhoe. The approximate test pit locations were determined by pacing from site features depicted on a preliminary site plan provided by the client. The elevations were estimated based on topographic data shown on the site plan. The locations and elevations of the test pits should be considered accurate only to the degree implied by the method used. These approximate locations are shown on the Test Pit Location Plan, Plate 2. j The field exploration was continuously monitored by a geologist from our firm, who I�'� classified the soils encou�tered, maintained a log of each test pit, obtained representative �� samples and observed pertinent site features. All samples were visually classified in ' accordance with the Unified Soil Classification System that is presented on Plate A 1 , �', Legend. Logs of the test pits are presented on Plates A2 through A16. The final logs �iI represent our interpretations of the field logs and the results of the laboratory tests on I field samples. The stratification lines on the logs represent the approximate boundaries ' between soil types. In actuality, the transitions may be more gradual. Representative soil ! samples were collected and returned to our laboratory for further examination and testing. ' Earth Consultants, Inc. t . MAJOR DIVISIONS GRAPH LETTER TYPICAL DESCRIPTION iSYMBOL SYMBOL � GW Well-Graded Gravels,Gravel-Sand Gravel o 0 0 And Clean Gravels Q Q a gW Mixtures, Little Or No Fines Gravelly Qittle or no (ines) M r / Coarse Soils � � � GP Poorly-Graded Gravels,Gravel- Grained � � � gp Sand Mixtures, Little Or No Fines Soils More Than (�jM Silty Gravels,Gravel-Sand- ,50h Coarse Gravels With gm SiN Mixtures Fraction Fines(appreciable Retained On amount oi finesl GC Clayey Gravels, Gravel-Sand- No.4 Sieve gC Clay Mixtures Sand �a oo 'a SVIf Well-Graded Sands, Gravelly And Clean Sand o o �' o � $W Sands, Little Or No Fines Sandy (little or no finesl q�.a�,,.: � � More Than � . SP Poorly-Graded Sands, Gravelly 50% Material Soils � v';;*�'� , Sp Sands, Little Or No Fines Larger Than More Than SM No.200 Sieve 50% Coarse Silty Sands, Sand- Silt Mixtures Size Sands YJith � SRl Fraction Fines(appreciable � , Passing No.4 amouni of fines; , SC Sieve � i'i' SC Clayey Sands, Sand-Clay Mixtures i ;, I I I I I I (NL Inorganic Silts&Very Fine Sands,Rock Flo�r,Silty- �p� Clayey Fine Sands;Clayey Si�ts w,�Slight Plasticity Fine Siits Liquid Limit � CL Inorganic Clays Of Low To Medium Plasticity, So Ised C�S Less Than 50 � C� Gravelly Clays, Sandy Clays, SiNy Clays, Lean � I � i � � QL Organic Silts And Organic � I � � � I O� Silty Clays Ot Low Plasticity More Than I I I I' MH Inorganic Silts, Micaceous Or Diatomaceous FmE mh Sand Or Si1ty Soils 50% Mater+al Silts Smailer Than And Liquid Limit C�..� Inorganic Clays Of High No.200 Sieve Clays Greater Than 50 Ch Plasticity, Fat Clays. Size �/// // �� H Organic Clays Of Medium To High � / / / Oh Plasticity, Organic SiHs `�� `�� `�� pT Peat, Humus, Swamp Soils Highly Organic Soils i, ��, ��r, �e (�t With High Organic ConteRts Topsoil 'y�'y�"� Humus And Dutf Layer Fill H;yhly Variable Constituents The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. DUAL SYMBOLS are used to indicate borde�line sal classification. C TORVANE READING,tsf I 2'O.D. SPUT SPOON SAMPLER qu PENETROMETER READING,tsf W MOISTURE, %dry weight � 24"I.D. RING OR SHELBY TUBE SAMPLER P SAMPLER PUSHED ! SAMPLE NOT RECOVERED i WATER OBSERVATION WELL pcf DRY DENSITY,Ibs.per cubic ft. LL LI�UID LIMIT, % Q DEPTH OF ENCOUNTERED GROUNDWATER PI PLASTIC INDEX DURING EXCAVATION t SUBSEQUENT GROUNDWATER LEVEL W/DATE Eat�th Consultants Inc. LEGEND ��iii�Yfuik.�ll��liw-�xs(Rz�lobuis6l��i�v�Hii�kr�i,�1�i��illfsls Proj. No.lo�88 Date Jan.2oo4 Plate A1 ' Test Pit Log j � Project Name: Sheet af II Laurelhurst 1 1 I Job No. Logged by: Date: Test Pit No.: I 10988 EW 12/31/03 TP-1 ' Excavation Contador. Ground Surface Elevation: NW E�acava6ng 402' Notes: ��a� w L $ L a � $ surface condaans: Depth of Topsoil 12": blackberry brambles Notes (%) `� �. p LL m � �. � � � � �, TPSL TOPSOIL � � SM Reddish brown silty fine SAND with gravel, loose, moist �a.3 2 -15.9%fines 3 9.8 ' 4 SM Gray silty medium SAND with gravel, medium dense, moist 5 6 -becomes ve dense Test pit terminated at 6.5 feet below e�asting grade. No groundwater encountered during e�acavation. NOTES: Test pits e�acavated by NW Excavating using a rubber tire backhoe. Elevations estimated based on topograph�c data contained on Preliminary Site Plan provided by client. 0 � N H � � U W � Q � Test Pit Log � Earth Consultants Inc. Laurelhurst � Q Cn�(Nr.[Y1nICdIFi�glrxYl5,Cx90k1gKf5SFItYIRNInMnf.lf}iCfflltlSFS wng County,Washington � a � � Proj.No. 10988 own. GLS Date Jan. 2004 Chedced SDD oate 1/28/04 Plate A2 Subsurfaoe conditions depicted represent our obsetvations at the time and location of this e�atory hole,modified by�gineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibility for the use or interpretation by others of c..�.,...,�rt�...,��o.,��.,.,rti:�i.,., ' Test Pit Log ` Prqed Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test PR No.: 10988 EW 12/31/03 TP-2 Ezcavation Contador: Ground Surface Elevation: NW Ezcavating 384' ' Nates: � o L �, � o surfaoe condaions: Depth of Topsoil 8" 'i General W I Notes (%) C� u''i � LL in � u�i I SM Reddish brown silty fine to medium SAND with gravel, loose, moist I � I ��.o I 2 ', s.3 _ � , 3 GP Brown poorly graded GRAVEL with sand, medium dense, moist to wet , w .. • •�• 4 -water see a e ' 9�5 5 SM Gray silty fine SAND with gravel, dense, moist , 6 -27.3%fines , -becomes ve dense ' Test pit terminated at 6.5 feet below e�asting grade. Perched groundwater seepage encountered at 4.0 feet during excavation. 0 � c � 0 � U W � Q � Test Pit Log �(� Earth Consultants Inc. �aurelhurst p GoMrctmfral Fi�gl�x�5.Cw�wogl.src h F�Mrcrin�rral SCV-ntl.� F King County,Washington a � W Proj.No. 10988 Dwn. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate A3 Subsurface conditions de�ided represent our obsenrations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot acoept responsibility for the use or interpretation by�hers of ;..�,,...,�+�.,.,„��o.,,d+,,..+ti��,,,, � Test Pit Log Projecf Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No.: 10988 EVV 12/31/03 TP-3 Excavation Contactor. Ground Surfaoe Elevation: NW Excavating 380' Notes: � o L „ N o surfaoe condn;ons: Depth of Topsoil 10" General W N�e$ ��p� � T Q LL l0 � T � � � � SM Reddish brown silty fine SAND with gravel, loose, moist � 14.5 2 . � . GP Brown poorly graded GRAVEL with sand, medium dense, moist to wet � 4.4 :.: 3 . � . � 4 •• • -medium water see a e 5 SM Gray silty fine SAND with gravel, medium dense, moist 6 -becomes very dense 15.9 � Test pit terminated at 7.0 feet below ebsting grade_ Perched groundwater seepage encountered at 4.0 feet during ezcavation. Q � � 0 � U W � a � Test Pit Log �(� Earth Consultants Inc. Laurelhurst O Gc�k�ctinkal Fngl�w�s,Gc�c�lsnA FnNrn�nx�nfal ticYHrtN� F King County, Washington a � F Proj.No. 10988 Dwn. GLS Date Jan. 2004 Checked SDD Date 1/28/04 Plate A4 Subsurface cond'Rions depided represent our observatior►s at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily reExesentative of other times and locations.We cannot accept responsibility for the use or interpretation by others of nfnrm�Finn nrxunfa�nn fhic liv. ` Test Pit Log ProjecA Name: Sheet of Laurelhurst 1 1 Job No. Loc,�ed by: Date: Test Pd No.: 10988 EW 12/31/03 TP-4 Ezcavation Contactor: Ground Surface Elevation: NW E�acavating 392' Notes: � o L „ N o su�face conditions: Depth of Topsoil 10" General W a Q Q . �- v � NOte$ ��p� � T � � a0 � T � � � � ,y TPSL TOPSOIL � � SM Reddish brown silty fine to medium SAND with gravel, loose, moist 12.7 ' ' 2 . � . GP Brown poorly graded GRAVEL with sand, medium dense, moist to wet � •. • 3 � • s.s • � • 4 -0.9%fines, ravel lens, medium water see a e SM Gray silty fine SAND with gravel, very dense, moist 9.9 5 Test pit terminated at 5.0 feet below e�as6ng grade. Perched groundwater seepage encountered at 3.5 feet during excavation. Q � c � 0 � U W � a � Test Pit Log � Earth Consultants Inc. �aurelhurst � cKxxrn,,,uaiFn�ne�-rs,c�-c+�isnhFnHmnn,erw,i�;aenn�s wng County, Washington � a WProj.t�o. 10988 Dwn. GLS Date Jan.2004 Chedced SDD Date 1/28/04 Plate A5 Subsurfaoe conditions depided re�xesent our obsenrations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannat accept responsibility f�the use or irrterpretation by others of a..s.,�..,�c...,..��o.,fd+.,.,�ti;�i.,., � Test Pit Log Projed Name: Sheet of Laurelhurst 1 1 Job No. Loc,7�ed by: Date: Test Pit No.: 10988 EW 12/31/03 TP-5 Ewcavation Co�tactor Ground Surface Elevation: NW E�acavating 400' Notes: � o L „ � o surtaoe conaai«,s: Depth of Topsoil 12" Genefal �N �� Q - o- � n �e$ ��p� � T 0 � l0 � >. (� (n (A (n y TPSL TOPSOIL � � SM Reddish brown silty fine to medium SAND, loose, moist 14.3 . � . z GP Brown poorly graded GRAVEL with sand, medium dense, moist to wet � •. • 3 16�9 •� 4 -gravel lens with only a trace of sand infilling •• • -water see a e 5 SM Gray silty fine SAND with gravel, dense, moist s -becomes very dense ��.0 7 -hea see a e from 4'filled excavation Test pit terminated at 7.5 feet below e�asting grade. Perched groundwater seepage encountered at 4.0 feet during excavation. � � � 0 n U W � Q � � Test Pit Log �(� Earth Consultants Inc. �aure�hurst O Gc�c�c'tmlcral PnghKxas.GcMoglsLs&Fnvfttinnx�nial Sck�n11� � King County, Washington a � F Proj.No. 10988 Dwn. GLS Date Jan. 2004 Checked SDD Date 1/28/04 Plate A6 Subsurface oonditions depided represent our observations at the time and bcation af this e�loratory hole,mod"rfied by engineering tests,anaysis and judgrnent. They are not nece,ssardy re{xesentative of o�her times and locations.We cannal acbept responsibility for the use or interpretation by others of nfivmalinn nruenn4�nn 4hic liw � Test Pit Log Projed Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No.: 10988 EW 12/31/03 TP� Excavation Contador. Ground Surface Elevation: NW E�acavating 394' �ar�: � o L „ � o surface condaions: Depth of Topsoil 12" Genefal W Q� g . a � � Notes ("/,) /6 i. p " m � i. C9 c� ul tn y TPSL TOPSOIL � � SM Reddish brown silty fine SAND with gravel, loose, moist a.s 2 SP-SM Brown poorly graded SAND with silt and gravel, loose, moist 7.9 ' a o,° 3 4 SM Gray silty fine SAND with gravel, dense, moist 5 6 -becomes very dense 12.5 7 Test pit terminated at 7.0 feet below e�asting grade. No groundwater encountered during excavation. 0 � � 0 c� U W � a � Test Pit Log (� �Ytrl C011SUIta11tS II�1C. Laurelhurst p fn�k�tYnikal Fngh�eca:s.Gr.�tltinR�Fnvlmnnxnr.�l k--k-nti�r.: F King County, Washington a wProj.No. 10988 Dwn. GLS Date Jan. 20Q4 Chedced SDD Date 1I28/04 Plate A7 Subsurfaoe oondikions depicted represent our observations ffi the time and bcation of this e�loratory hole,mo�f'�ed by engineering tests,analysis and judc,�nent. They are not necessarily representative of other times and bcations.We cannot accept responsibility for the use or inierpretation by others of i.�s.,..,,�4;n.�.,.ncunrarl„n 4h�o�.,.. ' Test Pit Log Project Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No-- 10988 EW 12/31/03 TP-7 Excavation Contactor: Ground Surfaoe Elevation: NW E�acavating 403' Nates: � — „ Surface cond�tions: Depth of Topsoil 12" General W � $ L � � � Notes % 1O �. °' `l � � i. � ) c�r cn � cn � tn �, TPSL TOPSOIL � � SM Reddish brown silty fine SAND with gravel, loose, moist 23.5 2 SM Brown silty medium SAND, loose,water bearing 19.1 3 SM Gray silty medium SAND,dense, moist a -cemented 5 -becomes medium dense ».� -caving s -fines increase � a s 10.9 10 Test pit terminated at 10.0 feet below e�asting grade. No groundwater seepage encountered during excavation. Q � � 0 � U W -� Q � Test Pit Log Earth Consultants Inc. Laurelhurst � �y��,��F.,R,;,�,��,�F.,w�,�,�-„��,�,h„�, King County, Washington � a wProj.No. 10988 Dwn. GLS Date Jan. 2004 Checked SDD Date 1/28/04 Plate A8 Subsurface conditions depided represent our observations at the time and location d this e�loratory hole,modified by engineering tests,analysis and judgment_ They are not neoessarily represent�ive of other times and bcations.We cannot accept responsibility for the use or interpretation by others d mfnrm�hnn nr«nn�dl nn 4f�ic I.v� ' Test Pit Log P�o�Ct Name: sneet of Laurelhurst 1 1 Job No. Logc�ed by: Date: Test Pit No.: 10988 EW 12/31I03 TP-8 Ezcavation Contactor: Ground Surfaoe Elevation: NW Ezcavating 399' Notes: � — m surface condaions: Depth of Topsoil 12" General W a B a �; a v � NOYBS ��p' � T � � W � T � � � � ,� TPSL TOPSOIL � � SM Reddish brown silty fine SAND with gravel, loose, moist to wet ' 20.4 2 3 -dECfe2S@ Ifl f8V21 SM Gray silty medium SAND with gravel, dense, moist to wet 4 �3.0 5 -becomes medium dense -fines increase s -caving � 13.4 $ Test pit terminated at 8.0 feet below e�dsting grade. No groundwater encountered during excavation. � � c � 0 � U W � a � � Test Pit Log � Earth Consultants Inc. Laurelhurst � � C'�i-c'Imk`alFngh�ev�s.Cw�*�tlst:skFnvlmnn�nr�IticN-ntix� King County, Washington H a � w Proj.No. 10988 Dwn. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate A9 Subsurfaoe cond'Aions depided represerrt our observations at the tane and location of this eaa�loratory hole,modified by engineering tests,analysis and judgmerrt. They are not neoessarily representative of other times and locations.We cannot accept responsibility for the use or interpretation by others of �..s�.,.,�+�.,.,.,.�e.,��,..,r�,:�i.,,. ` Test Pit Log Projed Name: Shee1 of Laurelhurst 1 1 Job No. La�ed by: Date: Test Pit No.: 10988 EW 12/31/03 TP-9 Excavafion Cmitador: Ground Surface Elevation: NW Excavating 393' Notes: 0 o L „ N o surfaoe condaions: Depth of Topsoil 12" General W �� %) c� �n � � u> > cn y TPSL TOPSOIL � � SM Reddish silty fine to medium SAND with gravel, loose, moist to wet 17�4 2 -heavy water seepage at 1' 3 SM Gray silty fine SAND with gravel, medium dense to dense, moist 4 5 -contains silt lenses 12A 6 Test pit terminated at 6.5 feet below e�asting grade. Perched groundwater seepage encountered at 1.0 feet during excavation. 0 � N F O � U W � a � � Test Pit Log � �Yrrl COl"1SUIt�I"1tS II"1C. Laurelhurst O cxlxcrtmk-alFngtrHxxs,Gc-cM�gt..t�&Fiivlmnnx�nra��inrntl�s King County, Washington � a � w Proj.No. 10988 Dwn. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate A10 Subsurface conditions depided represent our observations at the time and location of this e�loratory hole,modified by engineering tests,anafysis and judgment. They are not necessarily representativ�e of other times and bcations.We cannot accept responsibility for the use or interpretation by others of mfivmol�n..r.rnccn4ul nn lhic liv. � Test Pit Log ' Project Name: Shcet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No.: 10988 EW 12/31/03 TP-10 E�acavation Contactor. Ground Surface Elevation: NW Excavating 399' Notes: � — „ surrace conditions: Depth of Topsoil 12" Gener� W a g Q �; Q � � Notes (�/a) f0 �. p " m � � � � � � �, TPSL TOPSOIL � � � SM Reddish brown silty fine SAND with gravel, loose, moist 19.5 I 2 3 SM Gray to brown siity medium SAND with gravel, loose, moist »�� -medium water see a e at 4' 4 SM Gray silty medium SAND with gravel, medium dense to dense, wet 5 ', 6 -becomes moist ,I �3.s 7 -18.3%fines at 6.5' i $ II Test pit terminated at 8.5 feet below e�asting grade. Perched I�, groundwater seepage encountered at 4.�feet during excavation. j 0 � � � 0 � U W � � � 'I � Test Pit Log � �I��1 COt1SUlt�1tS IrIC. Laurelhurst � �`x"`�,n��F.,�,`"�".�,�,hF""'""'°,�"`�'<'"F""�` King County, Washington � a � � Prq.No. 10988 Dwn. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate A11 Subsurface oondftions depicted represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarify representati�e of other times and locations.We cannd aooept responsibility for the use or interpretation by others af �nf�xm�linn nroccn4erl nn 4hic I�v. ' Test Pit Log I � Projed Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No.: 10988 EW 12/31/03 TP-11 Excavation Contactor: Ground Surface Elevation: NW E�acavating 399' ��: � o = „ � surface condaions: Depth of Topsoil 6" �� (%� � N 0 LL' � � � SM Reddish brown silty fine SAND with gravel, loose, moist � 20.7 2 21-0 3 SM Brown silty medium SAND with gravel, loose to medium dense, moist 4 5 SM Gray silty medium SAND with gravel, dense, moist to wet 6 -water seepage � -becomes moist s s 13.7 10 Test pit terminated at 10.0 feet below ebsting grade. Perched groundwater seepage encountered at 6.0 feet during excavation. � c � 0 � U W � a c� � Test Pit Log �(� Earth Consultants Inc. �a��e�n��st p Gc�c�cf�nlcdFnglrx�x+.Gr�gt',K&Fnvlmui�v�IticNntk� King County, Washington H a wProj.No. 10988 Dwn. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate Al2 ' Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgrnent. They are not r�cessariy representative of other times and bcations.We cannot accept responsibi�ity for the use or irrterpretation by others of �.,�,,.,..�«�.,.,.,�ae„��.,.,aK i,,,. ' Test Pit Log ` Project Name: Sheet af Laurelhurst 1 1 Job No. Loc,�9ed by: Date: Test Pit No.: 10988 EW 12/31/03 TP-12 Excavation Contador: Ground Surface Elevation_ NW E�acavating 404' Nates: � o L „ N surface conditions: Deptfi of Topsoil 6" Notes (W � � o " � � � SM Reddish brown silty fine SAND with gravel, loose, moist to wet, weathered � 19�2 2 GP-GM Brown poorly graded GRAVEL with silt and sand, loose to medium dense, moist ».6 �' 3 -11.1%fines SM Gray sifty fine to medium SAND with gravel, very dense, moist 4 5 -becomes dense s 7 8 9.4 9 Test pit terminated at 9.0 feet below e�asting grade. No groundwater seepage encountered during excavation. 0 c � 0 c� U W � Q � Test Pit Log Earrn consulranrs ilzc. Laurelhurst � C-cxnrtmkalFngtr�a�.Gc��gtsis&Fnv�rmn�nra�ticlrnn�s King County,Washington � a � F Proj.t�o. 10988 Dvm. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate A13 Subsurface conditions depicted represent our observatans at the time and location of this e�loratory hole,mod'rfied by engineering tests,analysis and �udgrnent. They are nd necessarity representative of dher times and bcations.We cannot acoe{�responsibility for the use or interpretffiion by others of ��.�,��...,,,.�a.,��,..,�ti�i,,.. ' Test Pit Log ' Prqed Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No.: 10988 EW 12/31/03 TP-13 Ezcavation Contador: Ground Surface Elevation: NW Excavating 399' Notes: � — L „ � � surFaoe condaions: Depth of Topsoil 10" General W a� a _: a c� Notes (��) '� >, p " ,Ev j E, � � � � y TPSL TOPSOIL � � SM Reddish brown silty fine SAND with gravel, loose, moist 21.4 2 SM Brown silty fine to medium SAND with gravel, loose, saturated to water �s.2 3 bearing 4 SM Gray silty fine SAND with gravel, dense, moist 5 s -becomes medium dense 7 -increase in silt, becomes very dense 11.4 '' 8 Test pit terminated at 8.0 feet below e�asting grade. Perched groundwater seepage encountered at 3.0 feet during e�avation. 0 � � � 0 � U W a � � Test Pit Log (�� Earth Consultants Inc. Laurelhurst O Cn:cNrc'I�r�k`a)Fnglixtas,G:Oklgt'i_A'4 FiMrMtnx'rIX�rl tic'k�ntl.� King County, Washington H a ~ F Proj.No. 10988 Dwn. GLS Date Jan. 2004 Checked SDD Date 1/28/04 Plate A14 Subsurface conditions depicted represent our observations at the time and location of this e�loratory hole,modif�ied by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations We cannot accept responsibility for the use or interpretation by others af ._�_.__._. -- ` Test Pit Log � Prgea Mame: sneet of Laurelhurst 1 1 Job No. Logged by: D�e: Test Pit No.: 10988 EVN 12/31/03 TP-14 Excavation Contador: Ground Surface Elevation: NW Excavating 395' Notes: � o L m � o surface condrtrons: Depth of Topsoil 6" General 1N Notes (%) `� �. p " m � >. c7 �n u� cn SM Reddish brown silty fine SAND with gravel, loose, moist 19.4 � 2 I 14.3 SM Brown silty medium SAND with gravel, loose, moist to wet li 3 , 4 -522 a e SM Gray silty fine SAND with gravel, dense, moist 5 s -becomes medium dense to dense I'I � s I s -increase fines i�.s io Test pit terminated at 10.0 feet below e�asting grade. Perched groundwater seepage encountered at 3.5 feet during e�avation. 0 � h H O C� U W � Q � � Test Pit Log �(� Earth Consulranrs Inc. �.aure�hurst O Gcxxcrt rtilc'al Fn{{Ir�ra�.G'Mc�Rr:n 14 Firvlmnn krx�n�ticYrnft�i� � King County, Washington a � F Proj.No. 10988 Dwn. GLS Date Jan. 2004 Chedced SDD Date 1/28/04 Plate A15 Subsurface conditions depicted represe�t our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representative of other times and locations.We cannot accept responsibilily for the use or interpretffiion by others of .,F.....,��.,..r�e.,t�.,,.rti��.,.. ' Test Pit Log • Projed Name: Sheet of Laurelhurst 1 1 Job No. Logged by: Date: Test Pit No.: 10988 EW 12/31/03 TP-15 Ex�cavation Contactor. Ground Surface Elevation: NW Ezcavating 405' Notes: o — �, � surfaoe condaions: Depth of Topsoil 10" General W ° � N �Q.S ��p � T � LL IO � T ( ) c� cn � u> > cn SM Brown silty SAND with gravel, loose,wet � � 55.3 2 -water see e 3 ML Brown SILT with gravel, loose, moist to wet 19.8 4 i 5 SM Gray silty fine to medium SAND with gravel, dense, moist 15.0 6 -sand lenses � -caving s � s Test pit terminated at 9.0 feet below ebsting grade. Perched groundwater seepage encountered at 2.0 feet during e�acavation. 0 � N � � U W � a � Test Pit Log � Earth Consulranrs inc. �aurelhurst � ('x.aec7mkalFnglrNxa�,Gr.okigllv�6Fmlr��nxwalkitTitl� wng County,Washington � a � w Proj.No. 10988 Dwn. GLS �ate Jan.2d04 Chedced SDD Date 1/28/04 Plate A16 Subsurfaoe conddions depided represent our observations at the time and location of this e�loratory hole,modified by enginee�ir►g tests,anatysis and judgment. They are not necessariy representative of other times and locations.We cannot accept responsibilify for the use or interpretation by others of ..�...,..�r;...,.,.�a.,Fe,+.,..,tiK i.,,. • 4 APPENDIX B LABORATORY TEST RESULTS E-10988 Earth Consultants, Inc. � � Particle Size Distribution Report � C' - � - o 0 o v o - r� _ ' � C � u a � � � u u u �� i �; �:i I so I� ao I i� 70 � �' � j W � Z � ; _ j � w � '; � ' ; i; i W40 I � , � - -- a so 20 � ;i � ' ;� �; ' ( � �o � � o i i 200 100 10 1 0.1 0.01 0.001 GRAIN SIZE- mm %COBBLES %GRAVEL 96 SAND %SILT %CLAY USCS AASHTO PL LL 0 41_0 43.1 1�.9 SM ❑ 14.1 58.6 27.3 SM � 70.1 29.0 09 GP � SIEVE PERCENT FINER SIEVE PERCENT FINER SOII.DESCRIPTION -� ��on� c � � number �� oTP-I:2.0`-SM Reddish brown silty SAN size size �`' with gravel;Moisture 14.3% 1.5 100.0 100.0 100.0 #�4 �9.0 85.9 29.9 3/4 76.6 100.0 68.1 #8 �1.9 79.8 21.� ❑TP-2:4.5'-SM Gray silty SAND with 3/8 67.8 92.2 42.2 {�16 46.7 73.4 15.8 gravel;Moisture 9.5% #30 41.5 64.5 8.7 #50 32.8 �0.1 2•4 pTP-0:3.5`-GP Brown poorly graded GRA L #100 22.8 36.5 1.2 W�th sand;Moisture 6.6% #200 15.9 27.3 0.9 GRAIN SIZE REMARKS: �60 5.14 0.474 15.8 �✓ Tech:EL1�r �3p 0.249 0.0940 4.79 D10 0.674 ❑ Tech:F,LlL' COEFFICIENTS Cc 2.15 � Tech:ELW Cu 23.41 c Source: Sample No.:TP-1 Elev./Depth: 2' ❑Source: Sample No.:TP-2 Elev./Depth:4.�' o Source: Sample No.:TP-4 Elev./Depth:3.5' EARTH Client: Conner Homes Project: Laurelhurst CONSULTANTS, INC. ProectNo.: E-10988 Plate B� J � Particle Size Distribution Report C _ � g o0 0 0 m .n � C e� � u �' `9'u � � `a u u �� i� i I � i I � I � 80 � I � 70 - � W gp � il ` ii j W $o i � � U � � 1 i a ;� � � so zo io �� o � 200 �oo ��o � o_� o.o� o.00i GRAIN SIZE- mm %COBBLES %GRAVEL °,6 SAND %SILT %CLAY USCS AASHTO PL LL o 16.1 65.6 183 SM ❑ 50.1 3 8.8 11.1 GP-GM SIEVE PERCENT FINER SIEVE PERCENT FINER SOII,DESCRIPTION incnes � � number � � �TP-10:6.5'-SM Gray silty SAND with size size gravel;Moisture 13.8% 1.5 100.0 140.0 #4 83.9 49.9 3/4 96.0 78.6 �f8 75.3 39.3 ❑TP-12:2.5`-GP-GM Brown poorly grade 3/8 91.7 62.9 #16 66.1 34.0 GRAEL with silt and sand;Moisture 11.6°� #30 55.8 29.5 #50 40.8 22.8 #100 26.9 15.9 #200 18.3 11.1 GRAIN SIZE REMARKS: Qsp 0.769 8.21 O Tech:El,W D3p 0.179 0.639 p10 ❑ Tech:El:R% COEFFICIENTS C� Cu o Source: Sample No.:TP-10 Elev./Depth:6.�' ❑ Source: Sample No.:TP-12 Elev./Depth: 2.�' EARTH Client: ConnerHomes Project: Laurelhurst CONSULTANTS, INC. proectNo.: E-10988 Plate B2 � � DISTRIBUTION E-10988 3 Copies Conner Homes 846 - 108"' Avenue Northeast, Suite 202 Bellevue, Washington 98004 Attention: Mr. Paul 011estad 2 Copies Core Design, Inc. 14711 Northeast 29"' Place, Suite 101 � Bellevue, Washington 98007 Attention: Mr. Craig Krueger Earth Consultants, Inc.