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Home My WebLink AboutSWP271812�� (�y Ly� xe /�d- PREPARED FOR NORTHBAY DEVELOPMENT CORPORATION -y , , '// � I.," /. z' Keith Litchfield Geotechnical Engineer r�� of AN",+,, x RbWrt Levinson, P.E. �9F� 14591EP��` President s oNA� '-- GEOTECHNICAL ENGINEERING STUDY CITY LIGHTS APARTMENTS RENTON, WASHINGTON E-4218-1 June 15, 1989 Earth Consultants, Inc- 1805 - 136th Place Northeast Suite 101 Bellevue, Washington 98005 (206) 643-3780 222 East 26th Street, Suite 103 Tacoma, Washington 98411-9998 (206) 272-6608 RE6VVEQ MAY 2 2 1997 BUILDING DIVISION June 15, 1989 ' Northbay Development Corporation 633 North Mildred, Suite G Tacoma, Washington 98406 Attention: John Miller Subject: Geotechnical Engineering Study City Lights Apartments Renton, Washington Dear Mr. Miller: Earth Consultants Inc. Geotechnical FngineerS. Gc ologiSIS & Fm ironmental Scientists E-4218-1 ' We are pleased to submit herewith our report titled "Geotechnical Engineering Study, City Lights Apartments, Renton, Washington." This report presents the results of our field exploration, selective laboratory tests, and engineering analyses. The purpose and scope of our study was outlined in our April 27, 1989, proposal. Our study indicates that the site is underlain with competent bearing soil. Due to the limited access to the north end of the property we were unable to explore the area north of the drainage swale shown on Plate 2. We do not expect the subsurface conditions in the unexplored area to be vary significantly to those found in the -south. However, we should be contacted during the initial stages of construction to confirm that the northern subsurface conditions are consistent with the recommendations provided in this ' report. Based on the encountered conditions, and the results of our analyses, it is our opinion the ' proposed apartment buildings can be supported on conventional spread and wall footings bearing on the competent native soils or structural fill, depending on final grades. These recommendations, along with other geotechnically related aspects of the project, are discussed in more detail in the text of the attached report. 1805 -136th Place N.E., Suite 201, Bellevue, Washington 98005 Bellevue (206) 643-3780 Seattkgg(?q)4*8,ItXA,&4?q .4-608-60 Tacoma (206) 272-6608 Northbay Development Corporation June 15, 1989 E-4218-1 Page 2 We appreciate this opportunity to have been of service to you during this initial phase of ' project development, and we look forward to working with you in the future phases as the project comes to fruition. In the meantime, should you or your consultants have any questions about the content of this report, or if we can be of further assistance, please call. Very truly yours, EARTH CONSULTANTS, INC. Keith A. Litchfield Geofeclinical Engineer P i Robe t S. Levinson, P. E. President IKAL/RSL/kml I Earth Consultants, Inc. ' TABLE OF CONTENTS ' E-4218-1 Page INTRODUCTION Project Description..•..•....••.•........•...•.•,.•..•. 1 ' Scope of Services 1 SITE CONDITIONS Surface ............................................. 2 ' Subsurface ........................................... Groundwater 3 3 ' DISCUSSION AND RECOMMENDATIONS General............................................. 3 Site Preparation and General Earthwork ....................... Foundations .......................................... 4 5 Retaining Walls ........................................ 6 Slab -on -Grade Floors .................................... 7 Excavations and Slopes ................................... 8 Rockeries ............................................ 8 Site Drainage ......................................... 9 Pavement Areas ........................................ 10 LIMITATIONS ' Additional Services ...................................... 11 ' Appendix A - Field Exploration Appendix B - Laboratory Testing Appendix C - Associated Rockery Construction (ARC) Guidelines ' ILLUSTRATIONS E-4218-1 Plate 1 Vicinity Map Plate 2 Test Pit Location Plan ' Plate 3 Legend Plates 4 through 7 Test Pit Logs Plates 8 and 9 Grain Size Analyses Plate 10 Retaining Wall Drainage and Backfill Plate 11 Typical Footing Subdrain Detail Earth Consultants, Inc. ii i GEOTECHNICAL ENGINEERING STUDY 1 CITY LIGHTS APARTMENTS RENTON, WASHINGTON E-4218-1 INTRODUCTION Project Description The subject site is located in Renton, Washington, approximately as indicated on the Vicinity Map, Plate 1. The site is bordered to the north by multi -family residences, to the west by Benson Road South, to the east by school grounds, and to the south by undeveloped property. The purpose of this study is to explore the existing subsurface conditions at the site and, on this basis, to develop geotechnical recommendations for the proposed site development. We understand it is intended to develop the subject site by constructing several apartment buildings two to three stories in height. These structures will have a combination of concrete slab -on -grade floors and crawl spaces with supported wood frames. It is also possible some of these structures will require basement retaining walls. Cuts and fills are estimated to be up to ten feet in height. Rockeries may also be implemented into the final construction plans. While no specific design data are presently available, based on our experience with similar 1 construction, we estimate the total dead plus live loads are expected to be as follows: • Wall loads - 2 kips per lineal foot 1 • Column loads - 50 kips • Slab loads - 100 pounds per square foot (psf) If any of the above design criteria change, we should be consulted to review the recommendations contained in this report. In any case, we recommend that Earth Consultants, Inc. (ECI) be retained to perform a general review of the final design. 1 Scope of Services 1 We performed this study in general accordance with the scope of services outlined in our April 27, 1989, proposal. On this basis, our report addresses: • subsurface soil and groundwater conditions; • suitability of existing on -site materials for use as fill, or recommendations for 1 imported fill materials; • site preparation, grading and earthwork procedures, including details of fill 1 placement and compaction; 1 Earth Consultants, Inc. n 11 Northbay Development Corporation E-4218-1 June 15, 1989 Page 2 *short-term and long-term groundwater management and erosion control measures; • foundation support alternatives, including bearing capacity and resistance of lateral loads for conventional foundations; • estimates of potential total and differential settlement magnitudes; • rockery construction; • parking area and access roadway design pavement sections. This report has been prepared for specific application to this project 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 Northbay Development Corporation and their representatives. No other warranty, expressed or implied, is made. We recommend that this report, in its entirety, be included in the project contract documents for the information of the contractor. SITE CONDITIONS Surface At the time our study was performed, the site, proposed building locations, and our ' exploratory locations were approximately as shown on the Boring and Test Pit Location Plan, Plate 2. ' The site is heavily overgrown with deciduous trees, blackberry bushes, and thick underbrush. Two natural drainage swales run from east to west across the property. Light surface runoff was observed in both swales during our field work. However, during our site reconnaissance ' in December of 1987, heavy surface runoff was observed in the northern most swale which is six (6) to ten (10) feet deep. The site topography generally consists of slopes bordering the property along the west and east property lines and a relatively flat portion in the middle of the property between the slopes. A slope of 1.6H:1V (horizontal:vertical) to 3H:1V slope rises above Benson Road (west property line) for a horizontal distance of about twenty-five (25) feet. At the top of the slope the surface tapers off to a flatter portion that gradually slopes at about 6H:1V for a horizontal distance of approximately one -hundred and forty (140) feet to the eastern slope. The eastern slope is about 2.4H:1V for a horizontal distance of one -hundred (100) feet. Earth Consultants. Inc. 1 11 Northbay Development Corporation E-4218-1 June 15, 1989 Page 3 Subsurface The site was explored by excavating eight (8) test pits at the approximate locations shown on Plate 2. Please refer to the Test Pit Logs, Plates 4 through 7, for a more detailed description of the conditions encountered at each location explored. A description of the field exploration methods and laboratory testing program is included in the appendix of this report. The following is a generalized description of the subsurface conditions encountered. Our exploratory test pits generally encountered intermixed loose to medium dense silty sand and sandy silt two to five feet below the surface. Below the surface layer dense to very dense silty sand with variable amounts of gravel was encountered to the depths explored. The deeper soil is typically called "hardpan" or Glacial till. Access was limited in the northerly one hundred seventy (170) feet. A visual examination of this area indicates the subsurface conditions to be similar to the explored southerly portion of the site. Groundwater ' Groundwater seepage was observed in Test Pit 7 at ten (10) feet while excavating and is shown on the test pit log. However, the groundwater seepage level is not static; thus one may expect fluctuations in the level and flow depending on the season, amount of rainfall, ' surface water runoff, and other factors. Generally, the water level is higher in the wetter winter months. I Two natural drainage swales are aligned east to west across the property. At the time of our field work, light surface runoff was observed in the swales. ' DISCUSSION AND RECOMMENDATIONS General Based on the results of our study, it is our opinion the site can be developed generally as planned. It is evident the area of proposed development is underlain at a relatively shallow ' depth with competent bearing soil. The proposed buildings can be supported on conventional continuous and spread footings bearing on competent native soils or structural fill, depending upon final grade. Pavements and slabs can be supported on at least one foot of structural fill. The bearing soil for the structures is expected to be at a depth of about three to five feet below existing grade. I Earth Consultants, Inc. 1 Northbay Development Corporation E-4218-1 June 15, 1989 Page 4 The area north of the drainage swale (shown on Plate 2) was not explored due to limited access. This area is approximately one -hundred and seventy feet south of the north property line and the full depth, east to west, of the property. We do not expect the subsurface conditions in the unexplored area to be vary significantly to those found to the south. However, we should be contacted during the initial stages of construction to confirm that the northern subsurface conditions are consistent with the recommendations provided in this report. ' Two natural drainage swales cut east to west across the site. It appears from the site plan provided by the Johnson Braund Design Group that buildings will be located over these swales. Depending on the final site grades, the drainage swales may require as much as ten feet of fill. Prior to site regrading and fill procedures, the surface runoff carried by the ' swales will have to be rerouted to a suitable discharge, or a drainage pipe provided beneath the fill. At the time of our field work, the site soils were close to their optimum moisture content and may be suitable for use as structural fill. However, the site soils are moisture -sensitive and may become difficult or impossible to work or compact. In this case, you will need to ' import a clean, free -draining granular fill material. It appears that several basement or crawl space retaining walls may be included in ' construction. If so, they will need to be designed to retain the soils against which they are built. The inclusion of an adequate wall drain system is important to help avoid the potential buildup of hydrostatic pressure behind the walls. These and other geotechnically related aspects of this project are discussed in more detail in the following sections of this report. Site Preparation and General Earthwork All building and pavement areas should be stripped and cleared of all trees, surface vegetation, organic matter and any other deleterious material. We anticipate that a topsoil stripping depth of four to six inches will be required. IStripped materials should be removed from the site and disposed, or used in landscaping, as desired. The stripped material should not be mixed with any materials to be used as 1 structural fill. All fill material used to achieve design site elevations should meet the requirements for structural fill. I Earth Consultants, Inc. I' I ' Northbay Development Corporation E-4218-1 June 15, 1989 Page 5 Following the stripping operation, the ground surface where structural fill foundations, or slabs are to be placed should be proofrolled, and compacted to a reasonable non -yielding condition, and then probed. If any soft or unstable areas are encountered, they should be appropriately moisture conditioned and recompacted. If, after recompaction, they remain soft or unstable, they should be overexcavated to a depth that will provide a stable base. ' Typically, a depth of two to three feet is adequate for this purpose. The overexcavated unsuitable material should be removed and disposed. The resulting overexcavation should then be backfilled with either a compacted structural fill or crushed rock. Ideally, but articular) during wet weather, structural fill should comprise a free -draining, Y particularly g P granular organic -free material with a maximum size of three inches. It should contain less than 5 percent fines (silt and clay -size particles passing the No. 200 mesh sieve). During dry weather, any compatible non -organic soil meeting the above maximum size criterion may be used as structural fill. ' Structural fill under floor slabs and footings should be placed in thin horizontal lifts not exceeding ten inches in loose thickness. Each lift should be compacted to at least 95 percent of maximum dry density, as determined by ASTM Test Designation D-1557-78 (Modified Proctor). Fill under pavements and walks should be placed in similar thin horizontal lifts and, with the exception of the upper twelve (12) inches, be compacted to at least 90 percent of maximum density. The top twelve (12) inches should be compacted to at least 95 percent maximum density. Fills placed on any slopes steeper than 4H:1V should be benched into competent native soil. ' All fill material should be placed at or near the optimum moisture content. If the materials are too wet to be compacted to the required degree, it will be necessary to dry them or replace them with a more granular material. Fill materials can be dried by aeration or by intermixing cement powder to absorb excess moisture. Foundations The proposed structures can be supported on conventional spread footings provided the recommendations in this report are followed. The footings should bear on competent dense to very dense silty sandy gravel or on structural fill placed over competent native bearing soils, depending upon final grades and encountered soil conditions. Conventional spread footings can be designed on the basis of the following parameters: o Allowable soil -bearing pressure = 2500 psf 1 for native medium dense to dense silty sand and gravel and structural fill, including all dead and live ' loads. Earth Consultants, Inc. Northbay Development Corporation E-4218-1 June 15, 1989 Page 6 • Minimum depth of perimeter = 18 inches footing; below adjacent final exterior grade. • Minimum depth of interior = 12 inches footings; below top of floor slab. • Minimum width of wall footings = 18 inches • Minimum lateral dimension of = 24 inches column footings • Estimated post -construction = 1 inch, or less settlement • Estimated post -construction = 3/4 inch differential settlement; across building width A one-third increase in the above allowable bearing pressures can be used when considering short-term transitory wind or seismic loads. Lateral loads can be resisted by friction between the foundation and the supporting compacted fill subgrade or by passive earth pressure acting on the buried portions of the foundations. For the latter, the foundations must be poured "neat" against the existing soil or backfilled with a compacted fill meeting the requirements of structural fill: • Passive pressure = 300 pcf equivalent fluid weight • Coefficient of friction = 0.35 As a precautionary measure, we recommend drains be placed around all perimeter footings. More specific details of perimeter foundation drains are provided in the Site Drainage section of this report. Earth Consultants, Inc. Northbay Development Corporation E-4218-1 June 15, 1989 Page 7 Retaining Walls Depending on the final design plans, we understand basement or crawl space retaining walls may be used for some of the buildings. These walls must be designed to resist the loads imposed by the retained soils. We recommend the following parameters be used in wall design: • Walls unrestrained against = 35 pcf equivalent movement at the top fluid weight • Walls restrained against = 55 pcf equivalent movement at the top fluid weight These parameters assume adequate drainage behind the wall to prevent hydrostatic pressure buildup, and a level backfill surface. Floor or other surcharge loads are not included in these design values. If additional loads are to be applied, they should be added to the above design values. The restrained retaining wall lateral load values are for walls that are restrained against lateral movement at the top. Therefore, the wall should not be backfilled until construction of the floor level at the top of the wall is completed. When backfilled, the retaining walls must have a suitable drainage system installed, as described on Plate 11. Slab -on -Grade Floors Slab -on -grade floors can be used with conventional foundations provided they are placed on competent native bearing soil or on at least one foot of structural fill. Any fill or native soils disturbed by construction activity should either be recompacted or overexcavated and replaced with compacted structural fill or crushed rock. To prevent for moisture build-up on the subgrade, the slab should be provided with a capillary break consisting of a minimum of four inches of free -draining sand and gravel. We recommend that a vapor barrier, such as a 6-mil plastic membrane, be placed over the capillary break beneath the slab to reduce both water -vapor transmission through 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. n Northbay Development Corporation E-4218-1 June 15, 1989 Page 8 Excavations and Slopes Cuts on the order of ten feet are anticipated for this project. You should be aware excavation slopes, including utility trenches, be greater than the limits specified in local, state and Federal safety regulations. Temporary cuts greater than four feet in depth should be sloped at an inclination no steeper than 1:1 (Horizontal: Vertical). If slopes of this inclination, or flatter, cannot be constructed, or if excavations greater than four feet in depth are required, temporary shoring may be necessary. This shoring will help protect against slope or excavation collapse, and will provide protection to workmen in the excavation. If temporary shoring is required, we will be available to provide geotechnical shoring design criteria, if requested. All permanent cut and fill slopes should be inclined no steeper than .3H:2V and 2H:1V, respectively. These recommendation are applicable to slopes with a maximum height of ten feet. If higher slopes are anticipated, we should be contacted for the appropriate design and construction criteria. We also recommend that all excavated slopes be examined by ECI's representative at the time of construction to verify that conditions are as anticipated. Supplementary recommendations can then be developed, if necessary, to enhance stability. Such measures may include, but may not necessarily be limited to, flattening of slopes or installation of surface or subsurface drains. In any case, water should not be allowed to flow uncontrolled over the top of any slopes. All buildings should be set back a distance at least equal to the height of the slope to avoid imposing any structural load on the face of the slope. All permanently exposed slopes should be seeded with a vegetative cover as quickly after construction as is possible. The mat should comprise a deep-rooted, rapid -growth vegetation. This cover will help to reduce the potential for surface erosion and will help enhance the stability of the surficial layer of soil. It might also be prudent to use a pegged in -place geotechnical fabric to help hold the seed and mulch on the slope surface until such time as the root mat has an opportunity to germinate. Rockeries If the owner elects to use rockeries to protect the native cut slopes on the site, it should be understood they are not engineered retaining walls. Their construction is to a large extent an art not entirely controllable by engineering methods. Because of this, it is imperative that rockeries be constructed in a proper manner by contractors experienced in, and with a proven capability in, rockery construction. We have provided a set of Rockery Construction Guidelines for you and your contractor's use as Appendix C to this report. IEarth Consultants, Inc. Northbay Development Corporation E-4218-1 June 15, 1989 Page 9 Site Drainage We do not expect the site groundwater levels will present any major construction related problems. However, two natural drainage swales are aligned east to west across the site. If buildings or fills are located over these swales, the swales should be rerouted to a suitable discharge, or a drainage pipe provided beneath the fills. Once the rerouting is completed, the swales should be backfilled with compacted fill in accordance to the recommendations provided in the Site Preparation section of this report. During the earthwork the site should be graded such that surface water is directed off the site. Water should not be allowed to stand in any area where buildings, slabs or pavements are to be constructed. During construction, loose surfaces should be sealed at night by compacting the surface to reduce the potential for moisture infiltration into the soils. Final site grades should allow for drainage away from the building foundations. We suggest that the ground be sloped at a gradient of 3 percent for a distance of at least ten feet away from the buildings except in areas that are to be paved. ' If seepage is encountered in foundation excavations during construction, we recommend your contractor slope the bottom of the excavation to one or more shallow sump pits. The collected water can then be pumped from these pits to a positive and permanent discharge, such as a nearby storm drain. Depending on the magnitude of such seepage, it may also be necessary to interconnect the shallow sump pits by a system of shallow connector trenches. 1 If conventional spread footings are used, we recommend you install footing drains around the building perimeter. These drains should consist of a four -inch minimum diameter perforated or slotted rigid drain pipe laid at, or just below, the invert of the footing with a gradient ' iufficient to initiate flow. The drain line should be bedded on, surrounded by, and covered vith a free -draining washed rock, pea gravel, or other free -draining granular material. once the drains are installed, with the exception of the upper twelve (12), inches, the cavation can be backfilled with a granular fill material. The surficial twelve (12) inches fill should consist of compacted and relatively impermeable soil. It can be separated from underlying more granular drainage material by a layer of building_paper or visqueen. surface should be sloped to drain away from the building wall. Alternatively, the surface be sealed with asphalt or concrete paving. A typical detail is provided on Plate 11. -.r no circumstances should roof downspout drain lines be connected to the footing drain m. All roof downspouts must be separately tightlined to discharge. We recommend you 1 sufficient cleanouts at strategic locations to allow for periodic maintenance of the g drain and downspout tightline systems. Earth Consultants, Inc. Northbay Development Corporation June 15, 1989 E-4218-1 Page 10 tab We recommend the appropriate locations of subsurface drains, if needed, be time the seepage arease f present, during grading operations by ECI's representative at which may be more clearly defined. Pavement Areas The "adequacy of site pavements is strictly related to the condition of the underlying subgrade. If this is inadequate, no matter what pavement section is constructed, settlement or movement of the subgrade will be reflected up through the paving. We recommend the subgrade be treated as described in the Site Preparation section of this report. Depending on the nature of the prepared subgrade at the time of construction, it may also be necessary to use a geotechnical fabric to separate pavement materials from the underlying subgrade and to help strengthen the pavement section. We have provided you with two alternative pavement sections for the lightly trafficked access and parking areas. • 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. LIMITATIONS Our recommendations and conclusions are based on the site materials observed, selective laboratory testing and engineering analyses, the design information provided us by your architect, and our experience and engineering judgement. 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 from the test pits. Soil and groundwater conditions between the 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 then 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. Earth Consultants, Inc. I 11 t Northbay Development Corporation E-4218-1 June 15, 1989 Page 11 Additional Services We recommend that ECI be retained to perform a general review of the final design and specifications to verify that the earthwork and foundation recommendations have been properly interpreted and implemented in the design and in the construction specifications. We also recommend that ECI be retained to provide geotechnical services during construction. This is to observe compliance with the design concepts, specifications or recommendations and to allow design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. We can 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. N Earth Consultants Inc. Gearrhnkal Fsgineers. Geobglsts & Fmimnnx^nial Scirrnivs Proj. No. 4218- I Drwn. GLS Date May 89 SITE- SE X Reference King County / Map 41 By Thomas Brothers Maps Dated 1988 Vicinity Map City Lights Apartments Renton, Washington Checked KL Date 5/18/89 Plate 1 Property Line 410 400 - 410 -400 ' 390 n Ip_6r,,: IF-1- , I, TP-3 Limits of Unexplored Area I r i r � � I I TP-2 340 340 340 MNSON ROAD Existing 380 r Access Road n r3 Approximate Scale -,1P'5 1 370 r :,rf� O 25 50 IOOft. n LEGEND 360 TP-1 Approximate Location of ECI Test Pit, Proj. No. i E- 4218-1 , May 1989 350 Proposed Building Reference : Proj. No. 88 - 52 Site Plan By JohnsonBraund Dated 5 / 11 /89 Design Group, Inc. qq A P P F_ N D 0 A n u 1i APPENDIX A E-4218-1 FIELD EXPLORATION AND LABORATORY TESTING Our field exploration was performed on May 16, 1989. Subsurface conditions at the site were explored by excavating eight (8) test pits to a maximum depth of ten and one-half (10-1/2) feet below the existing grade. Approximate test pit locations were determined by pacing from property corners. Approximate test pit elevations were determined from a site plan provided by the Johnson Braund Design Group, Inc., dated May 11, 1989. The loca- tions 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. The field exploration was continuously monitored by a geotechnical engineer from our firm who classified the soils encountered and maintained a log of each test pit, obtained representative samples, measured groundwater levels, and observed pertinent site features. All samples were visually classified in accordance with the Unified Soil Classification System which is presented on Plate 3, Legend. Logs of the test pits are presented on Plates 4 through 7. The final logs represent our interpretations of the field logs and the results of the laboratory examination and tests of field samples. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. The consistency of the soil was estimated based on the effort required to excavate the soil, the stability of the trench walls, and other factors. Representative soil samples were placed in closed containers and returned to our laboratory for further examination and testing. Visual classifications were supplemented by index tests on representative samples. Moisture determinations were performed on all samples. Results of moisture determinations, together with classifications, are shown on the test pit logs ' included in this report. The results of the sieve analyses are illustrated on Plates 8 and 9, Grain Size Analyses. II r7 J Earth Consultants, Inc. GRAPH LETTER MAJOR DIVISIONS SYMBOL SYMBOL TYPICAL DESCRIPTION •0°'4,•0°•0 ' GW Well -Graded Gravels, Gravel -Sand Gravel o°Qoao:a a'o gW Mixtures. Little Or No Fines And Clean Gravels �..�..�. GP Poorly -Graded Gravels, Gravel - Gravelly (little or no fines) Coarse Soils gp Sand Mixtures, Little Or No Fines Grained GM Silty Gravels, Gravel-Sand- Soils More Than 50% Coarse Gravels With , gm Silt Mixtures Fraction Retained On Fines (appreciable amount of fines) GC Clayey Gravels, Gravel -Sand- No. 4 Sieve gC Clay Mixtures ° °° o o °o° ° ° SW Well -Graded Sands, Gravelly Sand And Clean Sand °ou° ° °° c p.o°O $yy Sands, Little Or No Fines SP Poorly -Graded Sands, Gravelly Sandy ( little or no fines 1 More Than 50% Material Soils Sp Sands, Little Or No Fines Larger Than More Than _ 1 •. ••.•' SM No. 200 Sieve 50% Coarse Sands With .E:i.�......::: """' SM Silty Sands, Sand - Silt Mixtures Size Fraction Fines (appreciable Sassing No.4 amount of fines) SC SC Clayey Sands, Sand -Clay Mixtures ML Inorganic Silts & Very Fine Sands, Rock FloLr,Silty- Ml Clayey Fine Sands; Clayey Silts w/ Slight Plasticity Fine Silts Liquid Limit CL Inorganic Clays Of Low To Medium Plasticity, Grained And Less T han 50 CI Gravelly Clays, Sandy Clays, Silty Clays, Lean Soils Clays Organic Silts And Organic � i jjj1jjj1jjj1jj! � � i Ol Silty Clays Of Low Plasticity MH Inorganic Silts, Micaceous Or Diatomaceous Fine More Than mh Sand Or Silty Soils 50% Material Smaller Than Silts Liquid Limit And CFI nClays Of High No.200 Sieve Clays Greater Than 50 CI1 Plasticityy , Fat Clays. Plasticity, Size Organic Clays Of Medium To High Oh Plasticity, Organic Silts Peat, Humus, Swamp Soils Highly Organic Soils - "'' Pt With High Organic Contents Humus And Duff Layer Highly 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 Notes : Dual symbols are used to indicate borderline soil classification. Upper case letter symbols designate sample classifications based upon lab- oratory testing; lower case letter symbols designate classifications not verified by laboratory testing. I 2-O.D. SPLIT SPOON SAMPLER �T 2.4" I.D. RING SAMPLER OR 11 SHELBY TUBE SAMPLER P SAMPLER PUSHED SAMPLE NOT RECOVERED SL WATER LEVEL (DATE) WATER OBSERVATION WELL Wo(,Earth onsuts Inc. technical Engineering and Geology C TORVANE READING, tsf qu PENETROMETER READING, tsf W MOISTURE, percent of dry weight pcf DRY DENSITY, pounds per cubic ft. LL LIQUID LIMIT, percent PI PLASTIC INDEX LEGEND Proj. No.4218-1I Date May' 89 ' Plate 3 1 1 1 1 1 1 1 1 1 1 TEST PIT NO. Logged By YAL Date 5-13-89 Elev. 369'±* Depth W (ft.) USCS Soil Description M 0 : SM Gray silty SAND, moist, medium dense 5 10 15 U 5 ES: Becomes dense at 5 feet 12 Becomes very dense at 6.5 feet 12 Glacial till Test pit terminated at 7.5 feet below existing grade. No groundwater seepage encountered during excavation. * Test pit elevations taken off of Topographic survey provided by Johnson Braund Design Group, Inc., dated May 11, 1989. Logged By 9AL TEST PIT N O. Date 5-1-13-89 sm Red silty SAND, damp, medium dense Reddish brown silty sandy GRAVEL, moist, dense heavily mottled seams and pockets of sandy silt. - cobbles at 6.0 feet Elev. 351' ±* 5 10 sm Becomes very dense at 9.0 feet 10 Gray silty SAND, moist, very dense 8 10 Glacial Till Test pit terminated at 10.5 feet below existing grade. No groundwater seepage encountered during excavation. 15 Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis, and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. TEST PIT LOGS CITY LIGHTS APARTMENTS 00,,Earth onsultants Inc. RENTON, WASHINGTON technical Engineering and Geology Proi. N0.4218-1' Date May' 89 I Plate 4 Depth (ft.) 0 5 10 15 9 5 10 15 TEST PIT NO. � Logged By KAL Date 5-13-89 Elev. 359'±* W USCS Soil Description N Logged By KAL 4Elev. 3 4 5 ' ± * Dates-13-89 TEST PIT NO. Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis, and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Earth ! i 11 Consultants Inc. Geotechnical Engineering and Geology TEST PIT LOGS CITY LIGHT APARTMENTS RENTON, WASHINGTON Proj. No. 4218-1 1 Date May' 89 ' Plate 5 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Depth (ft.) 0 5 10 15 C 10 15 TEST PIT NO. � Logged By KAL Date 5-13-89 Elev. 363'±* W USCS Soil Description N Logged BY 3-89L TEST PIT NO. Elev. 373'±* Date Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis, and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. _ _ 00,,Earth onsultants Inc. tech.11 Engineering and Geology TEST PIT LOGS CITY LIGHT APARTMENTS RENTON, WASHINGTON Proj. No. 4218-11 Date May' 89 I Plate 6 Depth (ft. ) # sm Reddish brown silty SAND, damp, medium dense 9 SM Light brown silty SAND, moist, dense 13 cobbles @ 6.5 feet ...... Mottled seams se_am_s @ 7.0 feet 11 sm Light reddish brown SAND with silt, moist to wet dense Q becomes wet @ 10.0 feet 10 Test pit termianted at 10.5 feet below existing grade. Moderate groundwater seepage encountered at 10.0 feet during excavation. 5 10 15 C TEST PIT NO. � Logged By KAL Date 5-13-89 USCS Soil Description Elev. 383'±* W Logged By KAL TEST PIT N O . E lev. 3 63 ' ± * Date 5-13-89 E�iill 5 ::. gp 10 Light brown silty SAND, moist, medium dense heavily mottled 14 - gravel @ 3.0 feet and dense 15 Gray silty SAND, damp, very dense, slightly mottled, glacial till 13 Test pit terminated at 6.5 feet below existing grade. No groundwater seepage encountered during excavation. 15' Subsurface conditions depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis, and judgement. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. TEST PIT LOGS Oft'Geotechnical Earth CITY LIGHTS APARTMENTS RENTON, WASHINGTON Ilk. Consultants Inc. Engineering and Geology Proj. No.4218-1 I Date May' 89 ' Plate I 0 Am �1 APPENDIX B E-4218-1 LABORATORY TESTING General We conducted laboratory tests on several representative soil samples to verify or modify the field soil classification of the units encountered and to evaluate the material's general physical properties and engineering characteristics. A brief description of each of the tests performed for this study is provided below. The results of laboratory tests performed on specific samples are provided either at the appropriate sample depth on the individual boring log or on a separate data sheet contained in this Appendix. However, it is important to note that these test results may not accurately represent the overall in -situ soil conditions. All of our recommendations are based on our interpretation of these test results and their use in guiding our engineering judgement. Earth Consultants, Inc. (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 thirty (30) days following completion of this report unless we are otherwise directed in writing. ' Soil Classification As mentioned earlier, all soil samples are visually examined in the field by our representative ' at the time they are obtained. They are subsequently packaged and returned to -our Bellevue office where they are independently reexamined by one of our engineers and the original description is verified or modified, as necessary. With the help of information obtained from ( classification tests, the samples are described in general accordance with the Unified Classification System, ASTM Test Method D-2487-83. The resulting descriptions are provided at the appropriate sample location on the individual test pit log and are qualitative only. ' The attached Soil Classification/Legend, Plate 3, provides pictorial symbols that match the written descriptions. Moisture Density Moisture content tests were performed on all samples obtained from the test pits. The i purpose of these tests is to approximately ascertain the in -place moisture content. The moisture content is determined in general accordance with ASTM Test Method D-2216-80. The results of these tests are presented at the appropriate sample depth on the boring logs. I Earth Consultants, Inc. ' Northbay Development Corporation E-4218-1 June 15, 1989 Page 14 Appendix B - Laboratory Testing E-4218-1 Page 2. Particle Size Anal Detailed grain size analyses were conducted on several of the shallow soil samples to determine the size distribution of the sampled soil. The information gained from this analysis allows us to provide a detailed description and classification of the in -place materials. In turn, this helps us to understand how the in -place materials will react when excavated and reworked during the construction effort. The results are presented on Plates 8 and 9, and classification symbols are provided as part of the appropriate individual sample descriptions on the test pit logs. IEarth Consultants, Inc. SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAWING tiro- D. . a. if t. min. o •�' ° , o 0 1ft. min. Compacted Subgrade LEGEND Surface seal; native soil or other low permeability material. a..• o• • . Free draining, organic free granular material with a maximum size of 3 inches, containing no more than 5 percent fines • (silt and clay size particles passing the No. 200 mesh sievel. Impermeable visqueen barrier or other impermeable material approved by geotechnical engineer. Weephole and drainage pocket as described below. O Drain pipe; pe rforated or slotted rigid PVC pipe laid with perforations or slots facing down; tight jointed; with a positive gradient. Do not use flexible corrugated plastic pipe. Drain line should be bedded on. and surrounded with free draining 1 inch minus rock or pea gravel, as desired. The drainrock may be encapsulated with a geo- technical drainage fabric at the engineers discretion. NOTES: • For free standing walls, weepholes may be used. Surround weep - holes with no less than 18 inches of 1 inch minus rock. RETAINING WALL DRAINAGE AND BACKFILL Earth CITY LIGHTS APARTMENTS I, Consultants Inc. consulting Engineers, Geologists RENTON , WASHINGTON V Environmental scientists Proj. No. 4218-1 Drwn. GLS Date May' 89 Checked KAL Dated May' 89 Plate 10 6 inch min. ~� ` SCHEMATIC ONLY - NOT TO SCALE NOT ACONSTRUCT|ON DRAWING DRAIN SLOPE TO 00 0. 4 inch min. diameter ----- 2 inch min./ 4 inch max LEGEND Surface seal; native soil or other low permeability material. Gravel baokfiU for vvaUm| VVDQT Standard Specifications, Section 9-03.12121. or Fine Aggregate for Port|ind Cement Conorete; Section 9-03.1121' Drain pipe; perforated or slotted rigid PVC pipe laid with \ / perforations or slots facing down; tight jointad; with m positive gradient. Do not use flexible corrugated plastic pipe. Do not Ua building downspout drains into footing lines. --' -- impermeable visqeen barrier or other impermeable material approved by Gaotechnioa| Engineer. 18inoh min. D inch min. TYPICAL FOOTING SUBDRAIN DETAIL Earth CITY LIGHTS APARTMENTS Consultants Inc. Consulting Engineers, Geologists RENTON, WASHINGTON I W & Environmental scientists ' �� DISTRIBUTION E-4218-1 4 Copies Northbay Development Corporation ' 633 North Mildred, Suite G Tacoma, Washington 98406 Attention: John Miller 1 ' 1 Copy Johnson Braund Design Group, Inc. 304 Main Avenue South, Suite 200 Renton, Washington 98055 ' Attention: Mel Easter 1 Fj n Ll Earth Consultants, Inc. APOW V OD f5Y NTOw 'PU�L�IG DATE -7 D c .� I c slyer 0 4 IZKS ��REG"f0� -------- L ocleN-C) p tZoJ ec-C t�50 U W7D4.Ry tor) NORTH I"= looI I Gi0 O I00 200 Soo CAWAFl416, S441,E INUJ FEET ►�100,% I I SHE E-C' 1 OF 1�; H W W ow Q a. 2 cc O U) . z^;; VW z �W �.„p+ ziO z� z= Q� N 4A z 0 V Jos No AFZI455- DATEJUL.SCALEDESIGNED DMAWN CHECKED AKROVED SHEET i8-.-A-5)0