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Home My WebLink About03221 - Technical Information Report - Geotechnical � e \ N GEOTECHNICAL ENGINEERING STUDY N (� ARBOR HEIGHTS SHORT PLAT � 329 RENTON AVENUE SOUTH 1 � J�f � � RENTON, WASHINGTON �� s� ��-��%�` , E-10931 ' December 18, 2003 � PREPARED FOR ARBOR HEIGHTS, LLC n-�1��`�"� �- ��a ��t...�,..�.�._. Mitchell G. McGinnis, LEG Project Geologist � -�� =; .:� �-� ( ��F�•� p �'3'1 � ��,,+� 1 Y,�� ;�.� "1`2�� . i� . � R+A$. ��. �'`,�`;J,c,d� ^ y��L� '�� '�� t.:;� �� s'�� 4 F`�G� -a ""i '.t:. ry � !F ��1 C r :�� j'"1 UI `,=,4�4+'�'� Z .X`� :� 4,�. .r, Ee.'��''� ,� : ;�.� '"� =;7 � ,� :�3 4 g2 p ,�-..'�.'".==� �f�1'1`��.r� ��'��i��.T,�•�9'�� :.r4��1�:. i,}¢�;':`S xp� ..�.,.�f�E'-�r.�.,:l ��C� h. ."t �,��. �� k ' �,�}�:��r?.�.-��—�...!`..`. �V.,.UJ...��_ /Z/�(/a3 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 � F�rtl� Cc�ns�:llta»ts, It�c�. � �- - �:5��t�i;�i��i ��,�_� c;cYniYimic.il I:n};iiuYy:ti,c�nln};ihiti N I:n�irnnnicnG�l tic k•nii�� ('1 AItiIfIK-tiOIl-R•�lill};ti I(7i(1�AA'.Ali()IIIti�MI-li�hl ti(Y-V'il"Cti December 18, 2003 E-10931 Arbor Heights, LLC P.O. Box 48194 Seattle, Washington 98146 Attention: Mr. Joe Megale Dear Mr. Megale: Earth Consultants, Inc. (ECI) is pleased to submit our report titled "Geotechnical Engineering Study, Arbor Heights Short Plat, 329 Renton Avenue South, Renton, Washington". This report presents the results of our field exploration, selective laboratory tests, and engineering analyses. The purpose and scope of our study were outlined in our November 17, 2003 proposal. Based on the results of our study, it is our opinion the subject property can be subdivided into two single-family residence lots and the western lot can be developed with a new single-family residence as planned. Support for the proposed residence can be provided using conventional spread and continuous footing foundation systems bearing on competent native soil or on newly placed structural fill. Slab-on-grade floors may be similarly supported. ', We appreciate this opportunity to have been of service to you. If you have any questions, or if we can be of further assistance, please call. Respectfully submitted, EARTH CONSULTANTS, INC. _" " /�I�'l.�` �� " "" l w'��ih� Mitchell G. McGinnis, LEG Project Geologist MGMIKMW/csm 1805 136ih Place N.E., Suite 201, Bellevue,WA 98005 Bellevue(425) 643-3780 FAX(425)746-0860 Toll Free(888)739-6670 1 � TABLE OF CONTENTS E-10931 PAGE INTRODUCTION.................................................................................................... 1 General ........................................................................................................... 1 ProjectDescription ........................................................................................... 2 SITECONDITIONS ............................................................................................... 3 Surface ........................................................................................................... 3 Subsurface ..................................................................... ............................... .. 3 Groundwater.................................................................................................... 4 LaboratoryTesting............................................................................................ 5 DISCUSSION AND RECOMMENDATIONS................................................................ 5 General ........................................................................................................... 5 Site Preparation and General Earthwork .............................................................. 6 Foundations..................................................................................................... 7 Rockery Recommendations................................................................................ 9 Retaining Walls ............................................................................................... 10 Slab-on-Grade Floors........................................................................................ 10 Seismic Design Considerations.......................................................................... 1 1 GroundRupture .......................................................................................... 1 1 Liquefaction ........................................................................................ .. ..... 1 1 Ground Motion Response............................................................................. 12 Excavations and Slopes.................................................................................... 12 Site Drainage .......... ...... 13 ' LIMITATIONS ...................................................................................................... 14 AdditionalServices .......................................................................................... 14 Earth Consultants, Inc. T TABLE OF CONTENTS, Continued I E-10931 ILLUSTRATIONS Plate 1 Vicinity Map Plate 2 Test Pit Location Plan Plate 3 Typical Rockery Detail j Plate 4 Retaining Wall Drainage and Backfill Plate 5 Typical Footing Subdrain Detail i APPENDICES '� Appendix A Field Exploration II Plate A 1 Legend Plates A2 through A4 Test Pit Logs Appendix B Laboratory Test Results Plate B1 Grain Size Analyses Appendix C Associated Rockery Contractors (ARC) Standard Rockery Construction Guidelines Earth Consultants, Inc. � F GEOTECHNICAL ENGINEERING STUDY ARBOR HEIGHTS SHORT PLAT 329 RENTON AVENUE SOUTH RENTON, WASHINGTON E-10931 INTRODUCTION General This report presents the results of the geotechnical engineering study completed by Earth Consultants, Inc. (ECI) for the proposed residential short plat at 329 Renton Avenue South in Renton, Washington. The general location of the site is shown on the Vicinity Map, Plate 1 . The purpose of this study was to explore the subsurface conditions within the western limits the single-family residence lot to assess the feasibility of developing the site with a new single-family residence, and to develop geotechnical engineering recommendations for the new residence. Specifically, our scope of services consisted of the folfowing: • Assessing subsurface soil and groundwater conditions, and their potential influence on the proposed site development; • Providing grading, earthwork, fill compaction, drainage, cut and fill slope inclinations, stripping, proofrolling, and other site development recommendations; � Providing temporary slope, or where applicable, shoring recommendations; • Assessing the suitability of existing on-site materials for use as structural fill, and providing recommendations for imported fill materials; • Providing design criteria for shallow foundations including minimum width and depth requirements and allowable design bearing pressures for shallow footings; and • Providing seismic design parameters. Earth Consultants, Inc. . GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 2 Project Description We understand it is planned to short plat an existing 13,500 square foot, rectangular shaped, residential lot into two, single-family residence lots of approximately equivalent size. Once the lot has been short platted, it is planned to develop the western lot with a new single-family residence. The eastern lot will contain the existing single-family residence. The northeast corner of the western lot contains an existing detached garage that will be removed to make way for the new single-family residence. Based on preliminary design information provided by the client, the proposed single-family residence will be two to three stories in height and will be constructed of relatively lightly- , loaded, wood frame construction with either slab-on-grade or wood joist floors. The new residence will likely be accessed from the north side of the property along a shared driveway that will extend out to Renton Avenue South. At the time of our study, the site, existing residence, and our exploration locations were , approximately as shown on the Schematic Test Pit Location Plan, Plate 2. No site plan was available at the time of our study. Based on our experience with similar projects, we anticipate wall loads will be on the order of 2 to 3 kips per lineal foot with column loads of 20 to 40 kips. We estimate slab- on-grade floor loads will be approximately 150 pounds per square foot (psf►. If the above design criteria are incorrect or change, we should be consulted to review the �ecommendations contained in this report. In any case, ECI should be retained to perform a general review of the final design. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 3 ' SITE CONDITIONS � Surface The subject site consists of an approximately 13,500 square foot, rectangular shaped, residential lot located approximately 450 feet north of the intersection of Renton Avenue ; South and Beacon Way South in Renton (see Plate 1 , Vicinity Map). The proposed development area is bordered to the north by an east-west trending access easement for an adjacent residential lot, to the south and west by existing single-family residences, and to the east by the existing single-family residence that will remain in the eastern lot I following the lot split. The northeast corner of the proposed development area contains an existing garage and concrete pavements that will be removed as part as the planned site improvements. The subject site is relatively level with less than five feet of elevation change throughout most of the site. The immediate northwestern corner of the lot contains an approximately 3 to 4 foot high, 40 foot long east-west trending rock wall constructed i along the north side of an upper bench that steps down along the wall to a lower bench at the base of the wall to the north. The immediate western portion of the site contains an approximately four to six foot high west-facing slope that descends from the subject site to the adjacent residential property to the west at around 50 percent. The immediate northern portion of the site contains an approximately four to six foot high north-facing slope that descends to the south side of the east-west trending access easement to the no�th of the site at a gradient of around 50 percent. The site is vegetated primarily with sod, small diameter trees, and decorative shrubs and plants. The lower bench that occupies the northwestern corner of the site is vegetated with plants and vegetables in a small garden area. Subsurface Subsurface conditions at the site were explored by excavating three test pits to a � maximum depth of thirteen (13) feet below existing grade. The approximate test pit locations are shown on Plate 2. Please refer to the Test Pit Logs, Plates A2 through A4 for a detailed description of the conditions encountered at each location explored. A description of the field exploration methods is included in Appendix A. The following is a generalized description of the subsurface conditions encountered. � Earth Consultants, Inc. � . � GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 1 8, 2003 Page 4 At our test pit locations, we encountered a surficial layer of topsoil and grass. The topsoil and vegetation layer was in the range of six (6) to twelve (12) inches thick. The topsoil is characterized by its dark brown to black color, loose consistency, and the presence of abundant roots and organic debris. The topsoil and vegetative layer is not considered 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 in Test Pits TP-1 and TP-2 we encountered three and one half feet of loose to medium dense fill comprised of silty fine sand (Unified Soil Classification SM). The fill was characterized by its dark brown color and its disturbed appearance. The existing fill is not suitable for direct support of the proposed residence in its present condition. The existing fill may be suitable for support of the proposed residence, provided it has less than 5 percent organics and it can be compacted to the requirements of structural fill. Underlying the topsoil and vegetative layer in Test Pit TP-3 we encountered silty fine sand to the bottom of the excavation at six and one-half feet. No fill was encountered in Test Pit TP-3. In Test Pit TP-3, the native sand was medium dense to around three and one half feet below grade before becoming dense. The soil became very dense at five feet below grade. Underlying the fill in Test Pits TP-1 and TP-2, we encountered one and one half to six feet of inedium dense poorly graded sand with silt (SP-SM) and poorly graded sand (SP), respectively. The poorly graded sand (SP) and poorly graded sand with silt (SP-SM) is underlain by dense to very dense silty fine sand (SM) to the maximum exploration depth of thirteen (13) feet below existing grade. Groundwater Light groundwater seepage was encountered in Test Pit TP-1 at five feet below existing grade. The observed seepage is likely indicative of seasonal perched groundwater flowing along the contact with the underlying dense to very dense, low permeability soil encountered at five feet below grade in Test Pit TP-1 . Earth Consultants, Inc. � � GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 5 Based on observed conditions, perched groundwater seepage may be encountered in footing and utility excavations if the grading is conducted during the winter vr spring. The contractor should be made aware that groundwater levels are not static. There will likely 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 classification and to evaluate the general physical prope�ties 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 resufts 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. DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, the single-family residence can be constructed generally as planned provided the recommendations in this report are considered in the project design. Support of the proposed residence can be provided using conventional spread and continuous footing foundation systems bearing on competent native soil or on newly placed structural fill. Slab-on-grade floors may be similarly supported. Earth Consultants, Inc. � � GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 6 The site is underlain by up to three and one half feet of loose to medium dense existing fill. The fill is not suitable for direct support of foundations in its present condition. If loose fill is encountered at construction subgrade elevations it should either be compacted in-place to the requirements of structural fill or it should be overexcavated and replaced with structural fill. Alternatively, the footing elements may be extended through the fill to underlying competent native soil. This report has been prepared for specific application to this project only 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 for the exclusive use of Arbor Heights, LLC 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 proposed building and pavement areas should be stripped and cleared of surface vegetation, organic matter, existing foundations and pavements, and other deleterious material. Based on the thickness of the topsoil and sod layer observed at the site, we estimate stripping depths will be in the range of six (6) to twelve (12) inches. Stripped materials should not be mixed with materials to be used as structural fill. Following the stripping operation the ground surface where structural fill, foundations, or slabs are to be placed should be observed by a representative of ECI. Soil in loose or soft areas, if recompacted and still yielding, should be overexcavated and replaced with structural fill to a depth that will provide a stable base beneath the general 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. Earth Consultants, Inc. , GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 7 Structural fill is defined as compacted fill placed under buildings, roadways, slabs, pavements, or other load-bearing areas. Structural fill under 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. Fill under pavements and walks should also be placed in horizontal lifts and compacted to 90 percent of the maximum density except for the top twelve (12) inches which should be compacted to 95 percent of the maximum density. During dry weather, most granular soils that are compactable and non-organic can be used as structural fill. Based on the results of our laboratory tests, the soils encountered at our test pit locations at the time of our field work appeared to be near their optimum moisture content and should be suitable for use as structural fill, provided the grading operations are conducted during dry weather. However, laboratory testing indicates some of the site soils are moisture sensitive with between 2 percent and 49 percent fines passing the No. 240 sieve. Soil with fines in excess of 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 condition. During dry weather, non-organic compactable granular soil with a maximum grain size of three 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 three 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 earthwo�k budget should be included for the possibility of importing a material meeting this specification. Foundations Based on the results of our study, it is our opinion the proposed single-family residence can be supported on conventional spread and continuous footing foundation systems bearing on competent native soil or on newly placed structural fill. Earth Consultants, Inc. a � GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 8 The site is underlain by up to three and one half feet of loose to medium dense fill. The existing fill is not suitable for direct support of the proposed residence in its existing condition. If loose fill or native soil is encountered at construction subgrade elevations it should either be compacted in-place to the requirements of structural fill or overexcavated and replaced with structural fill. Alternatively, the footing elements may be extended through the loose fill to the underlying competent soil. '� Exterior foundation elements should be placed at a minimum depth of eighteen (18) i inches below final 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 in accordance with local building codes. I With foundation support obtained as described, for design, an allowable soil bearing capacity of two thousand five hundred (2,500) psf for competent native soil, existing fill compacted in-place to the requirements of structural fill, or for newly placed structural fill can be used. 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 loading conditions, a one-third increase in the above allowable bea�ing capacities can be used. With structural loading as expected, total settlement of about one inch is anticipated with differential movement of about one-half inch. Most of the anticipated settlement should occur during construction as dead loads are applied. H�rizontal 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 conditions are as anticipated in this report. Earth Consultants, Inc. � -- a � GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 9 Rockery Recommendations The proposed development may include rockeries. A rockery is not intended to function as a retaining wall designed to resist lateral earth pressures. Rockery construction is largely a craft not entirely controllable by engineering methods. As , such, it is imperative rockeries are completed in close conformance with the ' Associated of Rockery Contractors (ARC) Standard Rockery Construction Guidelines and constructed by an experienced contractor with a proven ability in rockery '� construction. I A copy of the ARC Rockery Construction Guidelines is included in Appendix C. The sizing and placement of the rocks, drainage measures and other details of construction should be in conformance with the ARC guidelines. The face of the rockeries should i be inclined no steeper than 1 H:6V (Horizontal:Vertical). Drainage should also be installed behind the rockery. At a minimum, the drainage should consist of an eighteen (18) inch wide layer of two (2) inch to four (4) inch � quarry spalls placed along the full height of the rockery. A four-inch diameter perforated collector pipe should be installed at the base of the rockery. The collector pipe should consist of a rigid, schedule 40 PVC or SDR 35 drainpipe. We do not recommend using corrugated plastic pipe. The drain rock placed around the drain pipe should consist of pea gravel or washed rock. The rockery construction should be observed by a representative from ECI on a periodic basis. The purpose of our observations will be to verify our recommendations are followed and that the rockery is constructed in accordance with the ARC guidelines. The general recommendations contained in this section are for rockeries constructed against native cut slopes in areas where no structural or traffic loads will be applied. Rockeries that will exceed four feet in height and are constructed against fill need to be reinforced. ECI can provide recommendations for a reinforced rockery if requested. Please refer to Plate 3, Typical Rockery Detail for generalized rockery recommendations. Earth Consultants, Inc. . GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 10 Retaining Walls These recommendations pertain to free standing retaining walls and walls that are restrained at the top. Walls that are unrestrained should 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 and friction coefficients previously provided in the foundation section are applicable to retaining walls. To reduce the potential for hydrostatic forces building up behind the walls, the walls should be backfilled with a suitable free-draining material extending at least eighteen (18) inches behind the wall. The free-draining backfill should consist of washed rock or pea gravel extending the full height of the below grade portion of the wall. A rigid, schedule 40 PVC or SDR 35, perforated drainpipe should be placed at the base of the wall, and connected to an appropriate tightline discharge point. The pipe should be placed with the perforations in the down position. The backfill behind the drainage zone should consist of structural fill. Please refer to Plate 4, Retaining Wall Drainage and Backfill for a schematic drawing of a typical retaining wall. Slab-on-Grade Ftoors Slab-on-grade floors should be supported on competent native soil, existing fill compacted in-place to the requirements of structural fill, or on newly placed structural fill. The slab should be underlain by a capillary break consisting of a minimum of four inches of free-draining sand or gravel. In addition, 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. Earth Consultants, Inc. . - GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 1 1 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. There are three potential geologic hazards associated with a strong motion seismic event at this site: ground rupture, liquefaction, and ground motion response. Ground Rupture The strongest earthquakes in the Puget Lowland are widespread, subcrustal events, ranging in depth from thirty (30) to fifty-five (55) miles. Surface faulting from these deep events has not been documented to date. Therefore, it is our opinion, that the risk of ground rupture at this site during a strong motion seismic event is negligible. Liquefaction Liquefaction is a phenomenon in which soils lose all shear strength for short periods of time 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 provided the recommendations contained in our study are followed. Earth Consultants, Inc. , , . GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 12 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 So, Stiff Soil Profile from Table 16-J should be used for design. Excavations and Slopes The following information is provided solely as a service to our client. Under no circumstances 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 fill and native soils encountered at � our 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. The underlying dense to very dense native silty sand would be classified as Type A by OSHA/WISHA. Temporary cuts greater than four feet in height in Type A soils may be sloped to an inclination of 0.75H:1 V. If groundwater seepage is encountered or a soil unit is wet to waterbearing, it should be treated as a Type C soil and should be sloped accordingly. 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. Earth Consultants, Inc. GEOTECHNICAL ENGINEERING STUDY Arbor Heights, LLC E-10931 December 18, 2003 Page 13 Site Drainage Light groundwater seepage was encountered in Test Pit TP-1 at five feet below existing grade. The observed seepage is likely indicative of seasonal perched groundwater flowing along the contact with the underlying dense to very dense, low permeability soil encountered at five feet below grade in Test Pit TP-1 . Based on observed conditions, seasonal perched groundwater seepage could be encountered in site excavations if the excavations are conducted during the wet season. 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 discharge. Depending on the magnitude of such seepage, it may also be necessary to interconnect the sump pits by a system of connector trenches. The appropriate locations of subsurface drains, if necessary, 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. 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 residence. The ground should be sloped at a gradient of 3 percent for a distance of at least ten feet away from the residence. Footing drains should be installed around the perimeter of the proposed residence 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 Arbor Heights, LLC E-10931 December 18, 2003 Page 14 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 upon the data obtained f�om the test pits. Soil and groundwater conditions between test pits may vary from those I encountered. The nature and extent of variations between our exploratory locations may i 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. I 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. We do not accept responsibility for the performance of the foundation or earthwork unless we are retained to review the construction drawings and specifications, and to provide construction observation and testing services. Earth Consultants, Inc. � � _ , xJ� t 1 _�._ . r �' ; t � . , �-� I I i �i H — 5��-i — - -_ _ _. .�.� - - - 4.�K}.l,1 .y 2 I i i �r� ��» Y 4��,� - � �-. I i j , : _ _ � �, : . . . :y 3% .�. ,,,,r� I . . + i . y N ;TH :z ;T � <� c . '� � _ t / •• ,R�!�TbN ' ' ., '� ` � _ a i s } �'r> .� �t ' i i � � � ' Q a � � a ,r. c�; i_ � _ 'I - f C 1 'I` � I �: .C � �4 V S ... �• �i71 ecq ., � , iryU'�I��Pl�:'� - — �. .� .: ��H z •i :'•� . T ' _ � I+ , � � 1 . .� � , � �` � �F �`��" - . - I- ` ' M��J�T I � � � � � .J+. �l/ I J ' J i , . „�'L - � ._ � � � nl 5 -'� l � ��` �-' �. 3. i y �� ;Rt; �` � �f :•','b% .•�r �. '9G•. . .ry i __Y1.., . . _ J _* � � i . ��'/ . � t .4IRF'CrT jy�v . ¢ `` =, j • `�� I -_ST , }�, _ �, -�� S ; z,.t� .,,� _ _ / t r�E :�.. I . 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U I : �j /]ii � T' � <. ��.7 � ' 3 SW ,, �V (L'—` _ - - ,, '� �, 3 - `�'� . 1� ._ lr. _ .` D�'i . . � J t .. � — . .. _ _ , ('R/� _ `i�' , �, � o ,0�'` . a . � � .. . .�.,. _ L -:a - -' _ _ � F4,. �, , ;; ,_ �-,— .. .�, i �, , _ �— -. �� ^ � -�' :�`� i _; �, " �i _ �� ,F�W`� ," , _, � j.;;� _ . _ �_ -- �-- �'� '; ; .; i I ;�, � �W � / `` ' , 15n (f,r � - = ` - . . ;� �, , I ., : � � 16Ti1 `,T = i .i;-; �i � : - f� s � c ; � 1 , , � _ _ _ F . �� , _i . _ , _� ,L _ 7 ➢ y =� � ,.H ST �� . _J6;ir:~ •= . _ .. . Fc� a, r-- '- . _ ; �a n+ � ' c = `'- _�=i rn ' l - - ce _ . ,� � �, � �T� ,:'' �, � ; �,�� 4 .;tt . . � •�TH � v� S' Il�,t I� .? �� c �..� � � � , � � h � -, .�.;< _ ; _ _ .� _� � : .��,E . , �,. .;I :' -a Z�;F.�� S c.,�f� :�i I - .. . . .. ..� � � ` f ' :,r '� � } . , �_ " ' � w , _„ J +, _ �� __ .:.... � I Carth Consultants, Inc. Ref2f@f1C@: Geotechnical En�neering Geology.Environmental Scierxes Constructlon Tesling&ICBO/WABO Inspection Se�vic'.es King County Map 656 By Thomas Brothers Maps Vicinity Map Dated 2004 Arbor Heights Short Plat Renton, Washington NOTE: This plate may contain areas of color. ECI cannot be responsible for any subsequent Drwn. GLS Date Dec. 2003 Proj. No. 10931 misinterpretation of the information resulting from black &white reproductions of this plate. Checked MGM Date 12/10/03 Plate 1 r- - - -- - - - - - -- - - - - - - - - - - - - - - - - - -- -- _ _-- __i I I � � � � � —i Driveway � � i I TP-2 i —'— � � � �,�i � Y �Y�x J I i � � � i , Q � � 0 � � ; � o ' t W o� ; � t.i- I � � � � a -•- � , i TP-31 �i i Q � i � a, � I ` ' : �Z � � ��i ' � �i i .� i ml I a , �� ! , I TP-1 I � �x _�_ o� � ( al I � a � � y� � , � I � i . � � � ' - - - -- - - - -- - - -- - - - -- - 1— - - -- - - --- - - - -- - - - � � � � i LEGEND i TP-1—�—Approximate Location of ECI Test Pit, Proj. No. Not-To-Scale E-10931, Nov. 2003 � - - � � � Subject Site - - — � � Earth Consultants, [nc. � C,eolechnical Engineering Geology.Environmental Sciences Existing Building ConstrucrionTesting&ICBO/�vABOlnspection Senices Schematic Test Pit Location Plan Arbor Heights Short Plat NOTE: This plate may contain areas of color. R@CltOn, Washington ECI cannot be responsible for any subsequent misinterpretation of the information resulting Drwn. GLS Date Dec. 2003 Proj. No. 10931 trom black 8�white reproductions of this plate. Checked MGM Date 12/10/03 Plate 2 . . . i _��=�� I iii= �� , �='=�: ,--- .00 ; , =o: =o - , 6 4 °'' •;_'.III � D �a:� = r� � .. H ' 111= � - i °':a'�� —I I I '� / � •o. III ( � � 6 :o:�. I I I 1 '� - —III � � ` -111-�� 6 �� III ' '� = N—H \°� :a j�\�✓��,.o. �ca.� .... � 3 B - - - -- - � � I Fig. A ROCKERY SECTION Fig. B. ROCKERY ELEVATION � � All rodceries aver 4 feet in height should be constructed on basis of wall mass,not square footage of face. � SCHEMATIC ONLY- NOT TO SCALE NOT A CONSTRUCTION DRAWING Approximate Approximate Size Weight-Ibs. Diameter 1 man 50-200 12-18' NOTES: 2 man 200-700 18-28' Rockery construction is a craft and depends largely on the 3 man 700-2000 28-36' skil;l and experience of the builder. 4 man 2000-4000 36-48" A rockery is a protecfve system which helps retard the 5 man 4000-6000 48-54' I weathering and erosion process on an exposed soil face. 6 man 6000-5000 54�0' While by its nature(mass,size and shape of the rocks)it will prwide some degree af retention,it is not a designed Reference:Local quarry weight study using average weights i or engineered system in tfie sense a reinforced conaete of no less than six rocks of each man size conducted in � retaining wall would be considered designed or engineered. January 1988. ; ! The degree of retention achieved is dependent on the size LEGEND: ! of the rodc used;that is,the mass or weight,and the height o•,,a_�::: Drainage materials to consist of clean angular of the wall being constructed.The larger the rock,the more : o...-o:: well-graded quarry spalls,with 4-inch ma�cimum i competent the rockery should be. size,or other material approved by the geotechnical � Rockeries should be considered maintenance items that engineer. will require periodic inspection and repair.They should be located so that they can be reached by a oontractor if � Surface seal;may consist of impervious soil or a repairs become necessary. fine free draining granular material. Maximum inclination of the slopes above and behind rockeries should be 2:1 (Horizontal:Vertical). I I I I I I I I I Undisturbed firm Native Soil. Minimum thickness of rodc filter layer B=12 inches. Minimum embedment D=12 inches undisturbed native soil Drain pipe;4-inch minimum diameter,perforated or compacted fill placed in accordance with report O or slotted rigid plastic ADS pipe laid with a positive i recommendations. gradient to discharge under control well away from ! Maximum rockery height H= feet. the wall. Rockeries greater ihan 8 feet in height to be installed under periodic or full time observation of the geotechnical engineer. � Earth Consultants, Inc. Unless othenvise specified in writing by the rockery Geolechnical Engineers.Gedogists 8 Hnvironmenlal Scien�ists "designers,'all rocks placed in the lower two-thirds of the Construction Tesiing R ICBO r�n'n60 Inspection Services wall should be 5 to 6 man rock,4000 Ibs.or larger.Rocks placed above this level should gradually decrease in size with increasing all height using 3 to 5 man rock, ROCKERY DETAIL: NATIVE CUT, HEIGHT OVER 4 FT. � �oo to s000 ibg. Arbor Heights Short Plat The long dimension of the rocks should extend back towards the cut or fill fence to provide maximum stability. ReCltOrl, Washington Rocks should be placed to avoid con6nuous jant planes in vertical or lateral directions.Each rock should bear on two or more rodcs below it,with good flat-to-flat contact. DrV1m. GLS Dafi9 DeC. 2003 Proj. No. 10931 Chedced MGM Dafie 12/10/03 Plate 3 � . � Free Draining 18 inches min. Backfi I I ' o"o� °o o .' :. .: ;:.•::;;: 111=111=1111I1 Min 2"Dia. o° o �c 12 inches ' ,••;•• '� ��:•��•�: IIIIII I 0 o r;:: '.1=• ',.,.. Weep Hole o 0 0°�` :: '`: 0 o�c ''::oti,V::•'.o'o'�ooa •o•'•~'�' :•�_•�•"M I 0 o O �O- � O �pa�p °o O a� O :O: • 0 0 o a o '� . '�O� o� � C (O�O° � O o�po�o0 ••�l� 1J,o- I °� � 'b p Q o 0 0 0 o p�Qo ' • O .�o•� � .Q . Min. 6" 000 poo 1«Drain �°oa�oo ° o00 000 0 0:y.• o�.•. �°000 o Rock o0 0° �o 000°ao �•�p� •! \�. ��III�� o^00 0� o� °�� 0�0� o°o� �� •o•� �Excavated Slope 0 o a o 0 ��o 0 0� o o �� o o� p o �Q O o •• . � o� DOO� Oao o �.0.�.�� p �poo� �oo o° o 'rp• �. �� p � °��o Q�� ;'o'.�.c WEEP HOLE DETAIL ° � � � a �� ° •�.o•' 0 0 o a a o:: - o O� °� o 000 ooa O 0 0 0°o o o 0 00,o o ,:; Perforated Pipe I 111=111=111 0° °o ° o°o 0 0° ° -°= = Wrapped with 00 ifoot min. °°�-` �� Fifter Fabric o _ I 1 foot min. Compacted Subgrade i �� ' I , I STANDARD NOTES I F(�FNQ i I 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 o°o 0 0o Free Draining Backfill diameter. The percentage of particles passing the#4 sieve should be between o,:- 25 and 75 pericent. ■`'=•=o' Structural Fill com acted to 90 ercent ro::.•o:_: P P ' ' - ' ' relative compaction 2) Structural backfill should be free of organics, clayey soils,debris and other �ao'Oe°� ooe,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 of weep holes should be 6 feet. � Earth Consultants, Ir1C. Geotechnical Engineers.Geobgisis a Environmental Scientisis 4) Drain pipe; perforated or slotted rigid Conslruction Tesling 8 ICBO!WABO Inspeclion ServicCs , PVC pipe laid witfi perforations or slots facing down;tight jointed; with a positive RETAINING WALL DRAINAGE AND BACKFILL gradient. Do not use flexible corrugated Arbor Heights Short Plat plastic pipe. Drain line should be bedded Renton, Washington on and surround with free draining 1 inch � drain rock. The drain rock may be encapsulated with a geotechnical drainage Drvm. GLS Date Dec. 2003 Proj. No. 10931 fabric at the engineers discretion. Checked MGM Date 12/10/03 Plate 4 , ,• • Y ' I �� Slope To Drain _ �_' � •;;. � - � 6 inch min. ::;•: .,:. ':r:: �:r;j,: ';f,�: � ;:::`.-o:::�:o�o�a:�'••' .•-•o:�'„o;;o'o�•' '�o'o'Q o0o I .•o.o • o 0 0 • o 0 0 0 � p o�00 Qo QO Op O o��0 �o�O op p o Q� Qa o°o° o00 ° o�ooq�° o00 ° �Ooo°o° o00 ° �18inch i 0 oO��OooO o oO��000� o oO�Q i 0 oaa o o a o 00o a o 0 0 0o min. �po°�o a� o °000� °oo o� o °ooap °ao o I 0�00�000� � 0 0�000000� 00 o�poDo , o�p oo��o p 0 0 0��oa��o p � o o��oo� Qo0 000°�0 00 � 000 000°�p�oo ° Qo0 00 o ao ° o ao ° o 4inchmin. °o°000 00 0 000a000 00 0 000�0 o ° o 0 op o ° o 00 0 op p � o ° a j Diameter o o°o 0 0�o°°o o�o 0 0 0 0 Perforated Pipe \ oo�o o° o o p°oo�a o 0 W rapped in Drainage �° ° °o°°o �°o �� ° °�� ' 0 oa o0 oao o e o � , I 0 o a ,o 0 Fabric °oo o �o a oo, o o _� Ooo �O�QoOOo I o e a � o r I � I 2 inch min. I 2 inch min. /4 inch max. 12 inch min. iF�FNn - - � Surface seal; native soil or other SCHEMATIC ONLY- NOT TO SCALE low permeabitity material. NOT A CONSTRUCTION DRAWING 0 0 0 , 0 0 0 0 1� Drain Rock 000 0 o �o Drain pipe; perforated or slotted rigid O PVC pipe laid with perforations or � Earth Consultants, I nc. slots facing down;tight jointed;with a Geolechnical EngineerS Geobgisls&Environmenral Scieniisls Consiruction Tes�ing 8 ICBO/WABO Ins�ection 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 Arbor Heights Short Plat � or equivalent. Renton, Washington Drwn. GLS DateDec. 2003 Proj. No. 10931 Checked MGM Date 12/10/03 Plate 5 APPENDIX A FIELD EXPLORATION E-10931 Our test pit exploration was performed on November 24, 2003. The subsurface conditions at the site were explored by excavating three test pits to a maximum depth of thirteen (13) feet below existing grade. The test pits were excavated by Northwest Excavating, Inc., subcontracted to ECI, using a rubber-tired backhoe. The approximate test pit locations were plotted on a schematic drawing of the site sketched at the time of our field exploration. The test pit elevations were estimated relative to one another with an assumed base elevation of 125 feet for the lower bench in the northwest corner of the site. 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 Schematic Test Pit Location Plan, Plate 2. The field exploration was continuously monitored by a geologist from our firm, who classified the soils encountered, 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 A1 , Legend. Logs of the test pits are presented on Plates A2 through A4. The final logs represent our interpretations of the field logs and the results of the laboratory tests on 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 Consulta�ts, Inc. , . � MAJOR DIVISIONS GRAPH LETTER TYPICAL DESCRIPTION iSYMBOL SYMBOL d � (�W Well-Graded Gravels, Gravel-Sand GravEl o 0 0 And Clean Gravels Q � Q gW Mixtures, Little Or No Fines Gravelty (Gttle or no fines) � r GP Poorly-Graded Giavels,Gravel- Coarse Soils . • ■ Grained � � � gp Sand Mixtures, Little Or No Fines Soils More Than ,50% Coarse GM Silty Gravels,Gravel-Sand- Gravels With gm Silt Mixtures Fraction Fines(appreciable Retained On amount of fines) CaC Clayey Gravels, Gravel-Sand- No. 4 Sieve gC Clay Mixtures Sand � �o 00 ' SW Well-Graded Sands, Gravelly And Clean Sand o o �� c � SW Sands, Little Or No Fines Sandy 1l�ttle or no fines) 4 � q � More 7han '-4 : SP Poorly-Graded Sands. Gravelly 50q Material Soiis a p,,i;4,+o o', S(J Sands. Liltle Or No Fines , Larger Than More Than No.200 Sieve SM Silty Sands, Sand- Silt Mixtures Size 50% Coarse Sands With ! SfTI Fraction Fines(appreciabl•• � � Passing No.4 amount ot fines SC Sieve SC Clayey Sands, Sand-Clay Mixtures I I I I I I M L Inorganic Silts d Very Fine Sands,Rock Ro�r,Silty- �p� Clayey Fine Sands;Clayey Silts w/Slight Plasticity Fine Silts ! Inor anic Clays Of Low To Medium Plasticity, '� Liquid Limit CL 9 Gramed And Less Than 50 � C� Gravelly Clays, Sandy Clays, Silty Clays, Lean Soils Clays , � I � I � I OL Organic Silts And Organic � I � I � I p� Silty Clays Ot Low Plasticity I I I MH Inorganic Silts, Micaceous Or Dia,omaceous Fire More Than fllh Sand Or Silty Soils '� 50% Mater�al Silts Smaller Than And LiQuid Limit CH Inorganic Clays Ot High II No.200 Sieve Clays Grealer Than 50 C�l Plasticity, Fat Clays. Size i i// / / / �//�� OH Organic Clays Of Medium To High / / / / Ofl Plastici�y, Organic Silts `��' `��' `��' `� PT Peat, Humus, Swamp Soils Highly Organic Soils i, �, ��r, �i pt With High Organic Contents Tepsoil 'y'�'y`�'� Humus And Duff Layer Fill Hiyhly 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. OUAL SYMBOLS are used to indicate borderline soll classification. C TORVANE READING,tsf I 2"O.D. SPLIT SPOON SAMPLER qu PENETROMETER READING,tsf W MOISTURE, 96 dry weight � 24"I.D. RING OR SHELBY TUBE SAMPLER P SAMPLER PUSHED * SAMPLE NOT RECOVERED i WATER OBSERVATION WELL pct DRY DENSITY,Ibs. per cubic ft. LL LIQUID LIMIT,% Q DEPTH OF ENCOUNTERED GROUNDWATER PI PLASTIC INOEX DURING IXCAVATION 1 SUBSEQUENT GROUNDWATER LEVEL W/DATE �� Eatfil� Consultants Inc. LEGEND t.� (t�ukxlHiliall:ngu�ccq.(K�Ac�is�s619��•rturoix�ni,dStim�tlsls Proj. No. 10931 Date Dec. 2003 Plate A1 Test Pit Log ` P}oject Name: Sheet of Arbor Heights Short Plat 1 1 Job No. Logged by: Date: Test Pit No.: 10931 SSR 11/24l03 TP-1 Excavation Contactor: Ground Surface Elevation: NW Excavating 130' Notes: � o L �, � o Surface Conditions: Depth of Topsoil 8": grass General W L a . fl- � NOtPS ��p �i T � � N � T � C� �n � rn � cn SM Dark brown silty fine to medium SAND, loose to medium dense, moist (Possible Fill) � 2 3 • 4 SP-SM Brown poorly graded SAND with silt, medium dense, moist �o.a � a ° 5 -li ht see a e at 5' 12 9 SM Brown silty fine SAND, dense to very dense, moist s � -trace gravel -slightly cemented 8 -49.4%fines 9 -becomes light brown �o -decrease in moisture content 12.3 11 12 12.6 13 Test pit terminated at 13.0 feet below ebsfing grade. Perched groundwater seepage encountered at 5.0 feet during e�avation. NOTE: Test pit elevations estimated relative to one another with an assumed base elevation of 125 feet. 0 a � 0 c� U W � a � r Test Pit Log � �l�rl COt�1SUltaT11S Ir1C. Arbor Heights Short Plat c� o c<or�,��vc�ir;,Ri��.c�-ok>RivswF�rvim�n,�r,raiky�„n,r, Renton, Washington f- a � � Proj.rvo. 10931 �wn. GLS Date Dec. 2003 Checked MGM �ate 12/11/03 Plate A2 Subsurface conditions depicted 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 accept responsibility for the use or interpretation by others of .,s,.r.,,��.....,��a..,�...,,tiK i.,.. Test Pit Log � ► PrAjed Name: Sheet of Arbor Heights Short Plat 1 1 Job No. Logged by: Date: Test Pit No.: 10931 SSR 11/24/03 TP-2 � Excavation Contactor: Ground Surface Elevation: NW Ex�avating 125' Notes: � — „ surface condaions: Depth of Topsoil 12": grass I General W � $ L a `� �° Notes o m E °' " E � E I ��O� c7 �n � in � cn SM Dark brown silty fine to medium SAND, loose to medium dense, moist � (Possible Fill) 2 i 3 ; •o', 4 SP Brown poorly graded SAND, medium dense, moist 5.8 o e o ° o Q o . � o � -7 � o D -2./% IIneS I o�°,o� 6 -slight caving a � o a� o � o , o 'a o ° ° � s 000 0 ' 'a e 0 0 � 9 e ° o >>�$ ' SM Brown sil fine to medium SAND, dense, moist �o Test pit terminated at 10.0 feet below e�asting grade. No groundwater encountered during excavation. 0 a � 0 � U w a � Test Pit Log � Carth Consultants Inc. Arbor Heights Short Plat o c<xirt,y�nka�rnRi�x-�,�,a-oui�t,r,sFi�v�rca,n,�nmi xyrnn,e: Renton,Washington � a r- F Proj.No. 10931 Dwn. GLS Date Dec. 2003 Checked MGM Date 12/11/03 Plate A3 Subsurface conditions depicted represent 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 responsibility for the use or interpretation by others of ,.,�.....,�;.,.,..��e..��,,.,�ti��i.,,. Test Pit Log • Ptoject Name: Sheet af Arbor Heights Short Plat 1 1 Job No. Logged by: Date: Test Pit No.: 10931 SSR 11/24/03 TP-3 Excavation Contador: Ground Surface Elevation: NW Excavating 130' Notes: � o L „ � o suriace Conditions: Depth of Topsoil 6": grass General W L � � o- a a E a ... U Notes (%) `° �. p i'' � � Ea � � � � SM Brown silty fine SAND, medium dense, moist i 2 >> 7 3 -slightly cemented 4 -41.7%fines -becomes dense 5 -becomes very dense 9.4 6 Test pit terminated at 6.5 feet below e�asting grade. No groundwater encountered during excavation. 0 a � 0 c� U W a � Test Pit Log � F�lrtrl COr1SUlt�1tS Ir1C. Arbor Heights Short Plat � O Cr.<rctymk'alFngLx�ceti.Grc+kiglsr+F.t'nvlrainitnr.�l5c7rnr1�; Renton, Washington f- a �- W Prq.No. 10931 Dwn. GLS Date Dec. 2003 Checked MGM Date 12/11/03 P�ate A4 Subsurface conddions depided represent our observations at the time and location of this e�loratory hole,modified by engineering tests,analysis and judgment. They are not necessarily representat'rve of other times and locations.We cannot accept responsibitiry for the use or interpretation by others of �..Fnrma/inn nrmnMn.�l nn�hic I.v. APPENDIX B LABORATORY TEST RESULTS E-10931 Earth Consultants, Inc. , , , Particle Size Distribution Report c - < < o oa � - - H - C r� $ u � S� � � u u �' 1� � i.' � I �. � I,i I I '. 90 - � � � 80 70 - � � z 60 LL Z 5� W U W 40 d I 30 . ; i 20 10 - -- 0 20o ioo �o � o.� o.oi o.00i GRAIN SIZE - mm 9'o COBBLES °,6 GRAVEL °r6 SAND %SILT 96 CLAY USCS AASHTO PL LL 0 1.2 49.4 49.4 SM � 7.3 90.0 2.7 SP , 6.2 52.1 41.7 SM SIEVE PERCENT FINER SIEVE PERCENT FINER SOIL DESCRIPTION inches U � � number � � � �� TP-l:5'-SM size size �irown silty Sand; 12.94io moisture 1.5 100.0 100.0 100.0 �4 98.8 92.7 93.8 314 100.0 100.0 100.0 #8 96.4 85.4 90.5 O TP-2:4'-SP 3/fi 99.4 98.3 96.7 !!16 91.8 71.4 85.6 Brown poorly graded Sand;S.R°�o moisture #30 84.8 44.8 79.8 #50 72.6 13.8 67.5 #100 58.8 4.5 �2.] �TP-3:3'-S\t #200 49.4 2.7 q�.� BrownsiltySand; 11.7°�moisture GRAIN SIZE REMARKS: �60 0.161 0.848 0.216 o STs �30 0.444 �10 0.259 ❑STS COEFFICIENTS Cc 0.90 G S"I S Cu 3.28 o Source: Sample No.:TP-1 F_lev./Depth: 5' o Source: Sample No.:TP-2 Elev./Depth: �l' o Source: Sample No.:TP-3 Elev./Depth: 3' EART H Client: Project: Arbor Heights Short Plat,Renton CONSULTANTS, INC. ProectNo.: ];-]0931 Plate B1 APPENDIX C ASSOCIATED ROCKERY CONTRACTORS �ARC) STANDARD ROCKERY CONSTRUCTION GUIDELINES E-10931 Earth Consuitants, Inc. � � � �4RC o��ociated '�Zoclreey C�ant�actoca P.O. Box 1794 Woodinville, Washington 98072 (206) 481-3456 or (206) 481-7222 ASSOCIATED ROCKERY CONTRACTORS STANDARD ROCKERY CONSTRUCTION GUIDELtNES 1.01 Introduction: 1.01.1 Historica] Bac round: These standard rockery construction guidelines have becn developed in an effor[ to provide a more stringent degree of con[rol on rockery materials and construction methodology in the Pacific Northwest. They have been assembled from numerous other standards presently in use in the area, from e�cpertise provided by local geotechnical engineers, and from the wide experience of the members of the Associa[ion of Rockery Contrac[ors (ARC). 1.OlZ Goal: The primary goals of this document are to standardize the methods of construction for rockery walls over four feet in heigh[, and to provide a warran[y for the ma[erials used in cons[ruction and the �vorkmanship emp]oyed in cons[ruction. This standard has also been developed in a manner tha[ makes i[, to [he best of ARC's knowledge, more stringent than the other standards prescntly in use by ]ocal municipalilies. 2.01 Materials• 2.01.1 Rock Oualitv: All rock shall be sound, weathering resistant, angular ledge rock. The longest dimension of any individual rock should not exceed three times i[s shortest dimension. Acceptabiliry of rock will be de[ermined by lahoratory tests as hereinafter specified, geologic examina[ion and historical usage records. r�ll rock delivered [o and incorporated in the project shall meet the following minimum specifica[ions: a. Absorprion Nof more dta�i 2.0%for igrieous a�td metamorphic rock t}pes. Not more than 3.0%for sedimenlary rock types. b. .9ccelerated Expa�tsioli (1� da��s) (CRD-G148) "1, *2 � Not more diari IS% breakdown c. Soundness (MgSO4 at 5 cycles) Not greater t/iali S% loss (CRD-G137) d. Unconfzned Compressive Strengtlt IntaU strengih of I5,000 psi, or grealer for igneous a�:d ASTM D 2938-79 (reapproved 1979) metamorphicrocks, artd 8000psi orgreaterforsedinte�itaryrock *1. 77ie test sarnple will be prepared and lested in acco�dance with Corps of E'itgineers Testi�rg procedure CRD-C- 148, '1lMechod of Testing Scaie jor Fxpansi��e Brcakdown on Soaking in Eth��lenc Glycol." Test requi�ements of not nrore than IS percent breakdown will be computed by dividing the number of individua! preces of initial saniplr suffering breakdow�i ((l:at is, separating into ti+�o or ntore pieces) by the total number of initial pieces in tl:e suni�Je. *2. Accelerated crpartsio�i tesu should also i�tclude analyses of lhe fractures and veins jound i�i t/ie rock. Ma�i}� problenu ussocialed wilh rockery fnihires are relaled to 1he rock frachtres and veins found wilhin die ruck aird not l/ie rock itsc If. , , . 2.011 FrecLuencv of Testine: Quarry sources for rockery rock shall begin a testing program when either becoming a supplier or when a new area of the source pit is opened. The tests described in Section 2.01.1 shall be performed for every four thousand (4000) tons for the firs[ twelve thousand (1?A00) tons of material blasted and removed to establish that specific rock source. The [ests shall then be performed once a year or a[ an apparent change in material. If problems with a specific area in a pi[ or with a particular material are encountered, the initial [esting cycle shall be restarted. 2.013 Rock Densitv: Recogniung [hat numerous sources of rock exist, and [hat the nature of rock will vary not only be[ween sources but also within each source, the density of the rock shall be greater than one hundred Fifty- five (155) pcf. Typically, rocks used for rockery construction shall be sized approximately as follows: Rock Size Rock WeiQht Small to large 50-200 pounds one man Small to large 200-700 pounds two man Small to larse 700-2000 pounds three man Small to large 2040-4000 pounds four man Five Man 4000-60W pounds Six Man 6000-8000 pounds Two and one-man rock, and sometimes smaller, are often used to fill surface gaps along the [op of [he completed rockery to create an aesthetically pleasing surface. This is an acceptable practice provided none of the events described in Section 3.01.5 occur, and that the owner prevents people from climbing or walking on the completed rockery. In rockeries over eight fee[ in height, it should not be possible to move the Iarge sized rocks (four to six-man size) with a prybar. If these rocks can be moved, the rockery should not be considered capable of res[raining any significan[ lateral Ioad. However, it is both practical and even desirable that smaller rocks, particularly those used for "chinking" purposes, can be moved with a prybar to achieve the "best Fit". 2.01.4 Submittais: The rock source shall present current geologic and test data for the testing for the minimum guidelines described in Section 2.01.1 on request by either the rockery contractor, the client, or the applicable municipality. 3.01 Rockerp Construction: 3.01.1 General: Rockery construction is a craft and depends largely on the skill and experience of the builder. A rockery is a protective system which helps to re[ard the wea[hering and erosion process on an exposed cut or fill soil face. While by its nature ([he mass, size and shape of the rocks) it will provide some degree of reten- tion, it is not a designed or engineered system in the sense a reinforced concrete retaining wall would be considered designed or engineered. The degree of retention achieved is dependant on [he size of rock used; that is, the mass or weight, and the hei�ht of the wall being co�structed. The larger the rock, [he more competent the wall. To accomplish this, all rockeries in excess of four feet in hei�h[ should be built on a "mass" basis. To provide a competent and adequa[e rockery structure, all rockeries constructed in front of either cuts or fills in excess of eight fee[ in heigh[ should be bid and cons[ructed in accordance with these standard guidelines and the geotechnical engineers supplemental recommendations. Both the s[andard guidelines and the supplemental geotechnical recommendations should be provided to prospective bidders before bidding and the start of cons[ruc[ion. 2 � . . The same geotechnical engineer should be retained to monitor rockery construction and [o verify, in wricing, that the rockery was conscructed in general accordance with this ARC standard and wich his supplemental recommenda- tions, in a professional manner and of competent and suitable materials. 3.01.2 CTeotechnical Eneineer: The geotechnical engineer retained to provide necessary supplemental rockery construction guidelines shall be a practicing geotecl�nical/civil engineer licensed as a professional civil en�ineer in [he State of Washington who has at least four years of professional employment as a geotechnical en�ineer in responsible charge, including experience with r]( construction and s[ability and rockery construction. The geotechnical en�ineer should be hired either by the rockery contractor or the client. 3.01.3 Responsibility: The ul[ima[e responsibility for rockery "design" and construction should remain with the rockery builder. However, rockeries protecting moderate to thick fills, wi[h steep sloping surfaces above or below [hem, with multiple steps, with foundation or other loads affecting them, protecting sandy or gravelly soils subject to ravelling, with seepage or wet conditions, or [hat are more than eigh[ fee[ in height, all represent special conditions and require consultation and/or advice Irom qualified experts. 3.01.4 Workmanshin: All workmanship is guaranteed by the rockery con[ractor and all materials are guaranteed by supplying quarry for a period of six years from the date of completion of erection, providing no modiCication or changes to the conditions existing at the time of completion are made. 3.O1S Cl�anbes to Finished Produet: Such changes include, but are no[ necessarily limi[ed to, excavation of ditches or trenches within a distance of less than 1.5 times the rockery height measured from the toe of the rocker}�, removal of any material from the subgrade in fron[ of the rockery, excavation and/or removal of material from any location behind the rockery within a distance at least equal to the rockery's height, the addition of any surcharge or other loads within a similar distance of the top of the rockery, or surface or subsurface wa[er forced, directed, or o[herwise caused to flow behind the rockery in any quantity. 3.01.6 Slones: Slopes above rockeries should be kept as flat as possible, but should no[ exceed 2:1 (Horizon- tal:Vcrtical) unless the rockery is designed specifically to provide some restraint [o the load imposed by the s1oPe. Any slope exis[ing above a completed rockery should be provided with a vegetative cover by the o�vner to help reduce the potential for surface water t7ow induced erosion. It should consist of a deep roo[ed, rapid grov.th vegetative mat and typically will be placed by hydroseeding and covered with a mulch. It is often useful to overlay the seed and mulch with either pe�ed in-place jute matting, or some other form of approved geotechnical fabric, to help maintain the seed in-place un[il the roo[ ma[ has an opportunity to germinate and take hold. 3.01.7 Monitorin�: All rockeries constructed against cuts or fills in excess of eigh[ feet in height shall be periodically monitored during construction by the geotechnical engineer to verify the nature and quality of the materials being used are appropriate, that the construction procedures are appropriate, and [hat the wall is being cons[ruc[ed in a generally professional manner and in accordance wi[h this ARC standards and any supplemental recommenda[ions. On completion of the rockery, the geotechnical engineer shall submi[ to [he client, the rockery contrac[or, and to the appropriate municipali[y, copies oF his rockery examination reports along wi[h a final report summarizing rockery construction. 3.01.8 Fill Comnaction: Where rockeries are constructed in front of a fill, it is impera[ive [ha[ the owner ensure the fill be placed and compacted in a manner that will provide a competen[ fill mass. To achieve this goal, all fills should consist of relatively clean, organic and debris free, granular materials with a maximum size of four inches. Ideally, bu[ particularly if placement and compaction is [o take pIace during [be wet season, they should contain no more than five percent Gnes (sil[ and clay size particles passing the number 200 mesh sieve). All Glls should be placed in thin Iifts not exceeding ten inches in loose thickness. Each lift should be compacted to at leas[ 95 percen[ of the maximum dry density, as determined by ASTM Tes[ Method D-1S57-78 (Modified Proctor), before any additional G11 is placed and compacted. In-place density [ests should be performed a[ random locations within each lift of the fill to verify chis de�ree of compaction is bcing achieved. 3 � r • � 3.01.9 Fill Construction and Reinforcement: There are [wo methods of constructing a fill against which [o build a rockery. The firs[, which typically applies [o rockeries of less than eight feet in height, is to overbuild and then cut back che fill. The second, which appties to all rockeries in excess of eight feet in heigh[, is to cons[ruct the Fll using a geogrid or geotechnical fabric reinforcement. Overbuilding the fill allows for satisfactory compaction of the fill mass out beyond the location of the fill face to � be protected. Overbuilding also allows the earthwork contractor to use larger and more effective compaction equipment in his compactive efforts, thereby typically achieving a more competent fill mass. Cu[ting back into the well compacted fill also typically results in construction of a competen[ near vertical fill face agains[ which [o build the rockery. For the higher rockeries the use of a geogrid or geotechnical fabric to help reinEorce the fill results in construction of a more stable fill face against which to construct the rockery. This form of cons[ruction leads to a longer lasting and more stable rockery and helps reduce the risk of signiFicant long term maintenance. This latter form of construction requires a design by the geotechnical enpneer for each specific case_ The vertical spacing of the reinforcement, [he speciFic type of reinforcemen[, and the distance to which it must extend back into the Fill, and the amount of lapping must be determined on a rockery-by-rockery basis. 3.01.10 Rockerv T�evwa�^ The firs[ step in rockery construc[ion, after general site clearing and/or general excavation, is [o construc[ a keyway in which to build the rockery. The keyway shall comprise a shallo�� trench of between twelve (12) and eigh[een (18) inches in depth, extending for the full length of [he rockery, and inclined back slightly towards the face being protected. It is typically dug as wide as the rockery (including the width oE the rock Filter layer). If the condition of the protected face is oF concern, [he keyway should be constructed in sections of manageable length, tha[ is of a length that can be constructed in one shift or one days work. The competency of the keyway subgrade [o support the rockery shall be verified by probing with a small diameter steel rod. The rod shall leave a diameter of be[ween three-eights and one-half inch, and shall be pushed into the subgrade in a smooth unaided manner under the body weight of the prober only. Penetration of up to six inches, with some difFiculty, shall indicate a "compe[ent" keyway subgrade unless other factors in the geotechnical engineer's opinion shall indicate otherwise. Pene[ra[ion in excess of six inches, or of [hat depth with ease, shall indicate a "soft" subgrade and one tha[ could require treatment. Soft areas of [he subgrade can be "firmed up" by tamping a layer of coarse quarry spalls into the subgrade. 3.01.11 Kevwav and Rockerv Drainabe: On completion of keyway excayation, a shallow ditch or trench, approxi- mately twelve (12) inches �vide and deep, should be dug along the rear edge of the keyway. A minimum four- inch diameter perforated or stotted ADS drain .pipe, or equivalent approved by an engiueer, should be placed in this shallow trench and should be bedded on and surrounded by a free-draining crushed rock. Burial of [he drain pipe in this shallow trench provides protection to [he pipe and helps prevent it from being inadvertently crushed by pieces of the rockery rock. This drain pipe should be installed wi[h sufFcien[ gradient to initiate flow, and should be connected to a positive and permanen[ discharge. Posi[ive and permanent drainage should be considered to mean an e�cisting, or [o be installed, storm drain system, a swale, ditch or other form of surface water flow collectioa system, a detention or reten[ion pond, or other stable na[ive site feature or previously installed collection system. 3.01.12 Rockerv Thickness: The individual rockery Lhickness, including the rock filter layer, should be at least 40 percent of the rockery height. Unless otherwise specified in writing, [he individua] rocks should be arranged in a singIe course which, when measured [o include [he rilter layer, is equal to the required rockery thickness. 4 � „� v 3.01.13 Rock Selection: The contractor should have suI(icient space available so tha[ he can select from among a number of stockpiled rocks for each space in the rockery to be Cilled. Rocks which have shapes which do not match the spaces offered by the previous course of rock should be placed elsewhere to obtain a better fi[. Rock should be of a generally cubical, tabular or semi-rectangular shape. Any rocks of basically rounded or tetrahedral form should be rejected or used for filling large void spaces. Smaller rocks (one to two-man size, or smaller) are often used to crea[e an aesthetically pleasing "top edge" to a rockery. This is accep[able provided none of the events described in Section 3.01.5 occur, and that people are prevented from climbing or walking on the finished rockery. This is the owner's responsibility. 3.01.14 Rock Placement: The Cirs[ course of rock should be placed on Firm unyielding soil. There should be full contact between the rock and soil, which may require shaping of the ground surface or slamming or dropping [he rocks into place so that the soil foundation conforms to the rock face bearing on it. .As an alternative, it is sa[isfactory to place and tamp crushed rock into the subgrade to tighten it up. The bottom of the Frst course of rock should be a minimum oI twelve (12) inches below the lowest adjacent site grade. As the rockery is constructed, the rocks should be placed so [hat there are no continuous joint planes in either the vertical or lateral direction. Each rock should bear on at ]east [wo rocks below it. Rocks should be placed so [hat there is some bearing between Ilat rock faces rather than on joints. Joints between courses should slope downward towards [he ma[erial being protected (a�vay from [he face of the rockery). 3.01.15 Face Inclination: The face of the rockery should be inclined at a gradient of about 1:6 (Horizontal:- ' Vertical) back towards the face being protected. The inclination should no[ construc[ed flatter than 1H:4V. 3.01.16 Voids: Because of [he na[ure of the produc[ used to construct a rockery, it is virtually impossible to avoid creating void spaces between individual rocks. However, it should be recognized that voids do not necessarily constitute a problem in rockery construction. Where voids of greater than six inches in dimension exist in the face of a rockery they should be visually examined to determine if contac[ between the rocks exists within the [hickness of the rockery. If contac[ does exist, no further action is required. However, if there is no rock contact within the rockery thickness the void should be "chinked" with a smaller piece of rock. If a void of breater than six inches exists in the rear face of the rockery, it should be "chinked" wi[h a smaller rock. 3.01.17 Filter Laver. In order to provide some degree of drainage control behind the rockery, and as a means of helping to prevent loss of soil through the face of the rockery, a drainage Fil[er shall be installed layer between the rear face of. the rockery and the soil face being protected. This filter layer should be at least [welve (12) inches thick; and for walls in excess of eight feet in height, it should be at least eighteen (18) inches thick. It should be composed of four inch minus crushed rock, or other material approved by the geo[echnical engineer. If one of the rockery rocks extends back to the exposed soil face, it is not necessary tha[ [he filter rock layer extend between it and the soil face. In the event seepage is encountered emanating from a protected face, we recommend the use of a well-graded Filter layer. We do not recommend [he use of a geotechnical fabric for other than coverage of rela[ively small and isolated seepage areas because it has been the industr}�s experience that the fil[er fabric [ends to c]og rapidly. This quickly leads to a buildup of hydrostatic pressure which can subsequently cause failure and collapse of the rockery and is to be avoided. This clogging is apparently due to the virtual impossibility of achieving full contact between the soil face, fabric and rock filter material. If full surface contact cannot be achieved, there is of[en a tendency for the soil materials to flush from the pro[ected face into the "pocke[s" in the fabric which leads to the aforementioned clo�ing. 5 4 ,.. • 3.01.18 Surface Draina�e: It is the owner's responsibility to intercept surface drainage from above the rockery and direct it away from the rockery to a positive and permanent discharge well below and beyond the toe of che wall. Use of o[her drainage con[rol measures should be determined on a case-by-case basis by the geotechnical engineer prior to bidding on the projec[. 1/27/89 6 � � M DISTRIBUTION E-10931 4 Copies Arbor Heights, LLC P.O. Box 48194 Seattle, Washington 98146 Attention: Mr. Joe Megale Earth Consultants, Inc.