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HomeMy WebLinkAbout03029 - Technical Information Report - Geotechnical .� � 1 , l { .�. . �� `�. ,�_�� ` • . . � . � ' -r i+ � � �� Associated � I �:��. - � -, Earth fl � ' Geotechnical Engineering S c i e n c e s , ��--� � f1 C . � � � .�_ _ �---�.-� -_� _ � _ �.�-��:.� p,�:- �- � � _ �= �5 �- -.:�:� � I Subsurface Exploration, Geologic Hazards, and Water Resources � �'eliminary Geotechnical Engineering Report � � ����� :r` �: :��, J� � ODEGARD PROPERTY ; Y':> � PROPOSED MEDICAL OFFICE BUILDING �I � � ,�� , , '� � �` �� N Renton, Washington •�. � 1 . Solid and Hazardous Waste � i ' � . Prepared for �� �, , � Ms. Liz Odegard � � � � ��� � �� � ;�"'3 Project No. KE01085G �`~, March l3, 2001 ' � ' :�_ �.__ — Ecological/Biological Sciences � ��`F<Op � � �i�`Yy� o,�yF�� `,i, � � _ �qN� °f� _'��� f I - � - � ��c ��: -;� - �-- - ���,�„ r iI � k� _ �} � � Geologic Assessments � � ' . � � , 3 oz9 SUBSURFACE EXPLORATION, GEOLOGIC HAZARDS, AND PRELIMINARY GEOTECHIVICAL ENGINEERING REPORT ODEGARD PROPERTY � PROPOSED MEDICAL OFFICE BUILDING Renton, Washington Prepared for: Ms. Liz Odegard P. O. Box 165 Medina, Washington 98122 Prepared by: Associated Earth Sciences, Inc. 911 5`� Avenue, Suite 100 Kirkland, Washington 98033 425-827-7701 Fax: 425-827-5424 March 13, 2001 Project No. KE01085G l Odegard Properry Subsurjace Fxploration, Geologic Hazards, and Proposed ll�edical Ofjice Building Preliminary Geotechnical Engineering Repon Renton, Washington Project and Site Conditions I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration, geologic hazard, and preliminary geotechnical engineering study for the proposed medical o�ce building to be located north of the intersection of NE 4�` Street and Duvall Avenue NE in Renton, Washington. Our recommendations are preliminary in that definite building locations and/or construction details have not been finalized at the time of this report. We understand the cunent building location may be moved to accommodate a storm water detention facility. A rockery is also proposed along the west property line which is not shown on the Site and Exploration Plan, Figure 1. The approximate locations of the explorations accomplished for this study are presented on Figure 1. We were not provided the location of the building footprint until after our field exploration was completed. However, the explorations are located in the general area of the proposed building and paved areas. When definite building location and design details are available, the conclusions and recommendations contained in this report should be reviewed and modified, or verified, as necessary. 1.1 Purpose and Scope The purpose of this study was to provide subsurface data to be utilized in the preliminary design and development of the above-referenced project. Our study included a review of available literature, excavation of exploration pits, and performing geologic studies to assess the type, thickness, distribution, and physical properties of the subsurface sediments and ground water conditions. Limited geologic hazard evaluations and engineering studies were also conducted to determine suitable geologic hazard mitigation techniques, the type of suitable foundation, allowable bearing pressures, anticipated settlements, retaining wall lateral pressures, floor support recommendations, rockery construction, and drainage considerations. This report summarizes our current fieldwork and offers hazard mitigation and development recommendations based on our present understanding of the project. 1.2 Authorization Verbal authorization to proceed with this study was granted by Ms. Liz Odegard. Our study was accomplished in general accordance with our scope of work letter dated February 13, 2001. This report has been prepared for the exclusive use of Ms. Odegard and her agents, for specific application to this project. Within the limitations of scope, schedule, and budget, our services have been performed in accordance with generally accepted geotechnical engineering and engineering geology practices in effect in this area at the time our report was prepared. No other warranty, express or implied, is made. March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH/dn-KEOIQ85G2-D:Iwpldai3-01 Page 1 Odegard Property Subsurface Exploralion, Geologic Hazards, and Proposed Medical OJjice Building Preliminary Geotechnical Engineering Report Reraon, Washington Project and Site Conditions 2.0 PROJECT AND SITE DESCRIPTION This report was completed with an understanding of the project based on conversations with Balys Architects and Ms. Odegard, a topographic survey and proposed site plan by Modawell & Associates (undated), and our familiarity with previous geotechnical work performed in the site area. We completed a subsurface exploration program consisting of 11 exploration pits on March 2, 2001. Present plans call for the construction of a new medical office building. According to the site plan, the proposed building footprint will be roughly 10,000 square feet. Paved parking and driveway areas are currently planned north and west of the building with a loading dock on the southwest corner of the building. Although building construction details have not been finalized, we expect relatively light to moderate foundation loads commensurate with conventional wood or metal-frame construction. The site is currently undeveloped. A wetland bisects the property extending from its northeast to southwest corner. Flow of the stream through the wetland is from the northeast to the southwest. The remainder of the site is covered with blackberry, scottsbroom, and scattered maple, alder and willow trees, The property slopes gently to the southeast, with overall vertical relief across the site on the order of 15 feet. 'The highest site elevation is located along the west property line about 200 feet south of the northwest property corner. 3.0 SUBSURFACE EXPLORATION Our field study included excavating a series of exploration pits and performing a limited geologic hazard reconnaissance to gain information about the site. The various types of sediments, as well as the depths where characteristics of the sediments changed, are indicated on tl�e exploration logs presented in the Appendix. The depths indicated on the logs where conditions changed may represent gradational variations between sediment types in the field. Our explorations were approximately located in the field by measuring from known site features shown on tbe Site and Exploration Plan and their locations and elevations should be considered approximate. The conclusions and recommendations presented in this report are based on the exploration pits completed for this study. The number, location, and depth of the explorations were completed within site and budgetary constraints. Because of the nature of exploratory work below ground, extrapolation of subsurface conditions between field explorations is necessary. It should be noted that differing subsurface conditions may sometimes be present due to the random nature of deposition and the alteration of topography by past grading and/or filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed at that time, it may be necessary to re- evaluate specific recommendations in this report and make appropriate changes. March 13, 2001 ASSOCIATED EARTH SCIENCES,INC. SGH�Ca-KEOIO85G2-D:Ixp�dai3-01 Page 2 Odegard Property Subsurface F�ploration, Geologic Hazards, and Proposed Medical O�ce Building Preliminary Geotechnical Engineering Report Renlon, Washington Project and Site Conditions 3.1 Exploration Pits Exploration pits were excavated with a rubber-tire backhoe. The pits permitted direct, visual observation of subsurface conditions. Materials encountered in the exploration pits were studied and classified in the field by a geotechncial engineer from our firm. All exploration pits were backfilled 'unmediately after examination and logging. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. 4.0 SUBSURFACE CONDITIONS Subsurface conditions at the project site were inferred from the field explorations accomplished for this study, visual reconnaissance of the site, and review of topography provided on the previously mentioned Site and Exploration Plan. As shown on the field logs, the exploration pits generally encountered topsoil and fill materials above natural, glacial recessional outwash sand and gravel, overlying glacially consolidated till deposits consisting of silty sand with gravel and cobbles. The following section presents more detailed subsurface information organized from the upper (youngest) to the lower (oldest) sediment types. 4.1 Stratigraphy Topsoil/Fill Fill soils (those not naturally placed) were encountered to a varying extent in all exploration pits. The topsoil/fill ranged in thickness from as little as 8 inches in EP-7 to as much as 3 feet in EP-6 and EP-8, respectively. The fill averaged 2 feet thick across the site. As noted on the exploration logs, the fill primarily consisted of loose, moist, dark brown to gray, silty sand with gravel and abundant organics. In some areas the fill contained charcoal, wood, and minor debris including glass, plastic, and metal. Based on the organic character of most of the fill, it is likely that the fill was derived from dumping of topsoil stripped from adjacent properties during their development. The fill soils are not suitable for foundation support. Recessional Outwash Medium dense to dense, brown, clean to slightly silty sand and gravel, interpreted to be recessional outwash, was encountered in all exploration pits beneath the fill soils (except for EP-7) to depths of up to 10 feet. Recessional outwash sands and gravels were not encountered in EP-7. Recessional outwash consists of sand and gravel that was deposited by meltwater streams as the glaciers were retreating to the north after the last period of glaciation in the Puget Sound region, approximately 14,000 years ago. In general, these sediments were loose to a maximum depth below ground surface of approximately 4 feet and became medium dense March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH,'da-KEOIOSSG2-D:IKpldnt3-01 Page 3 � Odegard Property Subsurface Ezploralion, Geologic Hazards, and Proposed Medical Ofjice Building Preliminary Geotechnical Engineering Report Renton, Washington Project and Site Conditions to dense below 4 feet. The medium dense outwash is suitable for shallow spread footing ' foundation and pavement support, provided our recommendations are followed. The recessional outwash yields relatively large quantities of ground water that typically flows into � the on-site wetland. Therefore, special drainage provisions will likely be necessary to capture ground water and direct it away from the construction area. �Il Natural soils beneath the topsoil, fill, and recessional outwash materials consist of glacially consolidated till. The upper horiz�n of the till, interpreted as weathered till, consists of medium dense to dense, very moist, brown to gray, silty fine to medium sand with gravel. With increasing depth, these materials typically became denser. Unweathered till was encountered below the weathered till. The till represents the ground moraine of the southward advancing glacier and was therefore compacted to its very dense condition by about 1,000 feet of ice. This process resulted in a compact, cemented soil possessing high strength, low compressibility, and low permeability chazacteristics. The unweathered till commonly consists of very dense, moist to wet, gray, silty fine to coarse sand with gravel and cobbles. Either weathered or unweathered till was encountered at depths ranging from 8 inches in EP-7 to 10 feet in our other exploration pits. In EP-10 we were unable to excavate the exploration pit deep enough to identify till because of very rapid ground ' water seepage. The medium to very dense till soils are also suitable for direct foundation support. The site is mapped as Vashon glacial till on the Geologic Map of the Renton Quadrangle, Washington, by Mullineaux, 1965. Vashon Stratified Recessional Drift (recessional outwash) is mapped to the south and west of the site along the ancestral Cedar River floodplain. 4.2 Hydrology Very rapid ground water seepage was encountered in most of our exploration pits within the recessional outwash deposits at the time of our field study. Ground water was not encountered in EP-7 and EP-8. Only slow seepage was observed in EP-2. Ground water seepage at this site represents a "perched" condition. Perched ground water occurs when vertical infiltration is impeded by relatively impermeable soils and horizontal migration occurs. Typically, perched ground water develops at the interface between the topsoil/fill and silty weathered till or weathered till and unweathered till. However, at this site the clean recessional outwash provides a very permeable conduite for rapid ground water flow. Based on our explorations, it appears that the ground water elevations rise to about 3 feet below ground surface and the flow rate increases to very rapid within approximately 70 feet of the wetland. Increased ground water flow may be encountered following extended periods of wet weather or in response to March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH/da-KEOlA85G2-D:Ixpldnl3-01 Page 4 Odegard Properry Subsurface Fxploration, Geologic Hazards, and Proposed Medica!O�ice Building Preliminary Geotechnical Engineering Report Renton, Washington Project and Site Conditions changes in site use. The duration and quantity of flow generally depends upon several factors including topography, soil grain size and density, and season. March 13, 20�01 ASSOCIATED EARTH SCIENCES, INC. SGH/da-KEOI085G2-D:Iwpldal3-01 Page 5 Odegard Properry Subsurface F�plorarion, Geologic Hazards, and Proposed Medical OJj`'tce Building Preliminary Geotechnical Engineering Report Renton, Washington Geologic Hazards and Mitigations II. GEOLOGIC HAZARDS AND MITIGATIONS The following discussion of potential geologic hazards is based on the geologic conditions as observed and discussed herein. 5.0 SLOPE STABILITY HAZARDS AND RECOMMENDED MITIGATION Reconnaissance of this site was limited to the area shown on Figure 1. The site topography is relatively flat to gently sloping; and therefore, the risk of land sliding is low. 6.0 SEISMIC HAZARDS AND RECOMMENDED MITIGATION Earthquakes occur in the Puget Sound Lowland with great regularity. The vast majority of these events are small and are usually not felt by people. However, large earthquakes do occur as evidenced by the most recent 6.8 magnitude event on February 28, 2001, the 1949, 7.2 magnitude event, and the 1965, 6.5 magnitude event. The 1949 earthquake appears to have been the largest in this area during recorded history. Evaluation of return rates indicates that an earthquake of the magnitude between 5.5 and 6.0 is likely within a given 20-year period. Generally, there are four types of potential geologic hazards associated with large seismic events: 1) surficial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground motion. The potential for each of these hazards to adversely impact the proposed I, project is discussed below. 6.1 Surficial Ground Rupture Generally, the largest earthquakes that have occurred in the Puget Sound area are sub-crustal events with epicenters ranging from 50 to 70 kilometers in depth similar to the most recent February, 2001 event. For this reason, no surficial faulting or earth rupture as a result of deep, seismic activity has been documented, to date, in the area of the subject site. Therefore, � it is our opinion, based on existing geologic data, that the risk of surface rupture impacting the proposed project is low. 6.2 Seismically Induced Landslides The site topography is relatively flat to gently sloping; and therefore, the risk of land sliding is low. March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH/da-KE01085G2-D:Iwpldal3-01 Page 6 Odegard Property Subsurface Exploralion, Geologic Hazards, and Proposed Medical O�ce Building Preliminary Geotechnical Engineering Report Renlon, Washington Geologic Hazards and Mitigations , 6.3 Liquefaction The encountered stratigraphy has a low potential for liquefaction due to the high strength of the glacial soils. 6.4 Ground Motion The project site is located within a Zone 3 rating for seismic activity on a scale of 1 (lowest) to 4 (highest) based on the Seismic Zone Map of the United States, Figure No. 16-2 in the 1997 edition of the Uniform Building Code (UBC). This zonation is based on past earthquake activity in the Puget Sound region. As such, design recommendations in the report accommodate the possible effect of seismic activity in areas with a Zone 3 rating, corresponding to a peak ground acceleration of 0.3g (a Richter magnitude 7.5 earthquake occuning directly beneath the site), in accordance with UBC guidelines, using soil type Sc. This soil type corresponds to seismic coefficients: Ca = 0.33 and C� = 0.45. 7.0 EROSION HAZARDS AND MITIGATION Due to the large volumes of ground water expected at this site, we recommend construction of temporary ditches and drains to control ground and surface water and direct it away from the ' construction areas. Permanent ground water cut-off drains should also be constructed along portions of the west and north property Ime, where ground water will be mtercepted dunng construction of the proposed rockery and parking azeas. To mitigate and reduce the erosion hazard potential and off-site soil transport, we recommend the following: 1. All storm water from impermeable surfaces, including roadways and roofs, should be tightlined into detention/retention facilities and not be directed into the on-site wetland without City and County approved pre-treatment. 2. Temporary sediment catchment facilities should be constructed near the mouth of each of the main drainage gullies to intercept sediment eroded during the construction phases of the proposed project. 3. To reduce the amount of sediment transport, a silt fence should be placed along the edges of the wetland buffers and along the site perimeter. 4. Construction should proceed during the drier periods of the year and disturbed areas should be re-vegetated as soon as possible. March 13, 2001 ASSOCIATED EARTN SCIENCES, INC. scx,�-�oroasc2-D.Iwpldal3-01 Page 7 Odegard Property Subsurface Ezploration, Geologic Hazards, and Proposed Medical OJjice Building Preliminary Geotechnical Engineering Repon Reraon, Washington Geologic Hazards and Mitigalions 5. Control of surface discharge during and following development should be performed in order to reduce the hazard of erosion. Care should be taken to see that surface runoff and domestic discharge will not be directed into the on-site wetland without City and County approved pre-treatment. 6. Soils that are to be reused around the site should be stored in such a manner as to reduce erosion. Protective measures may include, but are not necessazily limited to, covering with plastic sheeting, the use of low stockpiles in flat areas, or the use of hay bales/silt fences. March 13, 20i01 ASSOCIATED EARTH SCIENCES, INC. SGH/dn-KEOI085G2-D:lxpldnl3-0/ Page 8 Odegard Property Subsurface Exploration, Geologic Hazards, and Proposed Medical O�ice Building Preliminary Geotechnical Engineering Report Renton, Washington Design Recommendations III. DESIGN RECONIl�IENDATIONS 8.0 INTRODUCTION Our exploration indicates that from a geotechnical standpoint, the parcel is suitable for the proposed development provided the risks discussed are accepted and the recommendations contained herein are properly followed. The bearing stratum of inedium dense recessional outwash, weathered till, and/or dense to very dense, unweathered till is relatively shallow and conventional spread footing foundations, which bear on these materials, may be used for building support. If proposed plans include relocation of the building, we suggest moving the building to the northwest, and constructing a ground water cut-off drain along portions of the north and west property line to obtain greater sepazation between shallow ground water and the proposed building parking lot and driveway subgrades. 9.0 SITE PREPARATION Prior to site grading, the contractor should make provisions for the control of ground water. The installation of french drains along portions of the north and west side of the property prior to site grading would help reduce seepage, disturbance, and unsuitable soil removal. French drains consist of perforated PVC pipes fully surrounded by pea gravel or washed rock. The drains should be as deep as practical, while still allowing gravity flow to a discharge point. The trench should be backfilled to the proposed cut elevation or to within 18 inches of finished grade with washed rock. Suitable excavated soils can be used to fill the remainder of the trench. Site preparation of planned building and road/parking areas should include removal of all trees, brush, debris, and any other deleterious material. Additionally, any organic topsoil, loose/soft fill, and any loose glacial soils should be removed. Any remaining tree roots should also be grubbed. The existing on-site silty sand or sand and gravel can be used as structural fill if it is thoroughly cleaned of cobbles larger than 6 inches in diameter, organics, and other deleterious materials. Areas where loose, surficial soils exist due to stripping and grubbing operations should be considered as fill to the depth of disturbance and treated as subsequently ' recommended for structural fill placement. ' March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH/da-ICE01085G2-D:Iwpldal3-01 Page 9 Odegard Properry Subsurface Exploration, Geologic Hazards, and Proposed Medical OJjice Building Preliminary Geotechnical Engineering RepoR Renton, Washington Design Recommendations Since the density and organic content of the existing surficial fill soil at the site is variable, random soft pockets may exist and the depth and extent of stripping can best be determined in the field by the geotechnical engineer. In the explorations completed for this study, medium dense recessional outwash and till soils (bearing strata) were generally encountered at depths of approximately 2 to 4 feet. The actual depth and extent of over-excavation and replacement will depend on the elevation and intended use of the area. We recommend that during construction, traffic across the exposed bearing soils should be � kept to a minimum during and after storm events, until the surface drains or dries. When these , materials are damp or wet it will result in disturbance of the otherwise firm stratum, creating contaminated runoff and possibly requiring removal of the top layer of mineral soils. Considering the weather pattems in the Pacific Northwest, wet silty sand may require long, hot dry periods to become useful as an adequate bearing surface or as structural fill. Therefore, earthwork and grading should be limited to dry weather conditions, if possible. We recommend that building, road, and parking areas be proof-rolled with a loaded, tandem- axle dump truck to identify any soft spots; soft areas should be overexcavated and backfilled with structural fill. If construction is to proceed during wet weather, we recommend systematic probing in place of proof-rolling to identify soft areas of the exposed subgrade. In our opinion, stable construction slopes should be the responsibility of the contractor and should be determined during construction. For estimating purposes, however, we anticipate that temporary, unsupported cut slopes in the medium dense to very dense glacial soils can be made at a maximum slope of 1H:1V (Horizontal:Vertical). However, the medium dense outwash may not stand for long periods of time at this inclination, especially if ground water is encountered. As is typical with earthwork operations, some sloughing and raveling may occur and cut slopes may have to be adjusted in the field. In addition, WISHA/OSHA regulations should be followed at all times. Some of the on-site soils contain a high percentage of fine-grained material, which makes them moisture-sensitive and subject to disturbance when wet. The contractor must use care during site preparation and excavation operations so that the underlying soils are not softened. If disturbance occurs, the softened soils should be removed and the area brought to grade with structural fill. Consideration should be given to protecting access and staging areas with an appropriate section of crushed rock or asphalt treated base (ATB). If crushed rock is considered for the access and staging areas, it should be underlain by engineering stabilization fabric to reduce the potential of fine-grained materials pumping up through the rock and turning the area to mud. The fabric will also aid in supporting construction equipment, thus reducing the amount of crushed rock required. We recommend that at least 10 inches of rock be placed over the fabric; however, due to the variable nature of March 13, 2001 ASSOCIATED EARTFI SCIENCES, INC. SGH,'da-KE01085G2-D:l�splda'.3-01 Page 10 Odegard Property Subsurface Exploration, Geologic Hazards, and Proposed Medical OJj`'ice Building Preliminary Geotechnical Engineering Report Renlon, Washington Design Recommendations the near-surface soils and differences in wheel loads, this thickness may have to be adjusted by the contractor in the field. 10.0 STRUCTURAL FILL All references to structural fill in this report refer to subgrade preparation, fill type, placement, and compaction of materials as discussed in this section. If a percentage of compaction is specified under another section of this report, the value given in that section should be used. The building footprint location is expected to change from that shown on Figure l, and floor elevations were not provided to us. However, placement of structural fill may be necessary in order to achieve the desired site grades in some areas. A civil engineer can best determine `cut and fill' amounts for the project and site. After stripping, excavation, and any required overexcavation has been performed to the satisfaction of the geotechnical engineer, the upper 12 inches of exposed ground in building areas or areas to receive fill should be recompacted to 90 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. If the subgrade contains too much moisture, adequate recompaction may be difficult or impossible to obtain and should probably not be attempted. In lieu of recompaction, the area to receive fill should be blanketed with washed rock or quarry spalls to act as a capillary break between the new fill and the wet subgrade. Where the exposed ground remains soft and further overexcavation is impractical, placement of an engineering stabilization fabric may be necessary to prevent contamination of the free-draining layer by silt migration from below. After recompaction of the exposed ground is tested and approved, or a free-draining rock course is laid, structural fill may be placed to attain desired grades. Structural fill is defined as non-organic soil, acceptable to the geotechnical engineer, placed in maximum 8-inch loose lifts with each lift being compacted to 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. In the case of roadway and utility trench filling, the backfill should be placed and compacted in accordance with current local or county codes and standards. The top of the compacted fill should extend horizontally outward a minimum distance of 3 feet beyond the location of the perimeter footings or roadway edge before sloping down at an angle of 2H:1 V. The contractor should note that Associated Earth Sciences, Inc. (AESI) must evaluate proposed fill soils prior to their use. This would require that we have a sample of the material 48 hours in advance to perform a Proctor test and determine its field compaction standard. Soils in which the amount of fine-grained material (smaller than No. 200 sieve) is greater than approximately 5 percent (measured on the minus No. 4 sieve size) should be considered March 13, 20iD1 ASSOCIATED EARTH SCIENCES, INC. SGH/da-KEOIQ45G2-D:1wp1dal9-0i Page 11 � Odegard Property Subsurface Fxploration, Geologic Hazards, and Proposed Medical Office Building Preliminary Geotechnical Engineering Repon Reraon, Washington Design Recommendations moisture-sensitive. Use of moisture-sensitive soil in structural fills should be limited to favorable dry weather conditions. The majority of on-site soils expected for use in structural fills generally contained less than 10 percent silt. These soils are, therefore, considered slightly moisture-sensitive. These materials can be used over a wider range of moisture contents than very silty, moisture-sensitive soils. In addition, construction equipment traversing the site when the soils are wet can cause considerable disturbance. If fill is placed during wet weather or if proper compaction cannot be obtained, a select import material consisting of a clean, free-draining gravel and/or sand may need to be used. Free-draining fill consists of non-organic soil with the amount of fine-grained material limited to 5 percent by weight when measured on the minus No. 4 sieve fraction. A representative from our firm should inspect the stripped subgrade and be present during placement of structural fill to observe the work and perform a representative number of in- place density tests. In this way, the adequacy of the earthwork may be evaluated as filling progresses and any problem areas may be corrected at that time. It is important to understand that taking random compaction tests on a part-time basis will not assure uniformity or acceptable performance of a fill. As such, we are available to aid the owner in developing a suitable monitoring and testing program. 11.0 FOUNDATIONS Spread footings may be used for building support when founded directly on medium dense, recessional outwash or on structural fill that extends down to the aforementioned bearing soils if placed as previously discussed. We recommend that an allowable bearing pressure of 2,500 pounds per square foot (ps fl be utilized for design purposes, including both dead and live loads, for footings placed on medium dense, native glacial soils or structural fill extending down to this strata. An allowable bearing pressure of 4,OQ0 psf can be utilized for footings placed entirely on dense to very dense, outwash or unweathered till. An increase of one-third may be used for short-term wind or seismic loading. Perimeter footings should be buried at Ieast 18 inches into the surrounding soil for frost protection; interior footings require only 12 inches burial. However, all footings must penetrate to the prescribed bearing stratum and no footing should be founded in or above loose, soft, or organic soils. To limit settlements, all footings should have a minimum width of 24 inches for two-story structures. It should be noted that the area bounded by lines extending downward at 1H:1V from any footing must not intersect another footing or intersect a filled area which has not been compacted to at least 95 percent of ASTM:D 1557. In addition, a 1.SH:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undernune the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils or adjacent to the existing ditch on the west property line. March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH;'dQ-KEOlP85G2-D.Iw�Ida13-01 Page 12 Odegard Property Subsurface Exploration, Geologic Hazards, and Proposed Medical Office Building Preliminary Geotechnical Engineering Repon Renton, Washington Design Recommendations Anticipated settlement of footings founded as described above should be on the order of 1 inch or less. However, disturbed soil not removed from footing excavations prior to footing placement, could result in increased settlements. All footing areas should be inspected by AESI prior to placing concrete, to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. The goveming municipality may require such inspections. Perimeter footing drains should be provided as discussed under the section on Drainage Considerations. 12.0 LATERAL WALL PRESSURES We understand a storm water detention facility (possibly a vault) is planned for the property. A loading dock with retaining walls is also planned near the southwest corner of the building. Therefore, this section provides lateral wall pressure criteria to aid in design of these walls. All backfill behind walls or around foundation units should be placed as per our recommendations for structural fill and as described in this section of the report. Horizontally backfilled walls, which are free to yield laterally at least 0.1 percent of their height, may be designed using an equivalent fluid equal to 35 pounds per cubic foot (pcfl. Fully restrained, horizontally backfilled rigid walls, which cannot yield, should be designed for an equivalent fluid of 50 pcf. If parking areas are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. The lateral pressures presented above are based on the conditions of a uniform backfill consisting of on-site, glacial soils, compacted to 90 percent of ASTM:D 1557. A higher degree of compaction is not recommended, as this will increase the pressure acting on the wall. A lower compaction may result in settlement of structures, utilities, or pavements placed above the walls. Thus, the compaction level is critical and must be tested by our firm during placement. Surcharges from adjacent footings, heavy construction equipment, or sloping ground must be added to the above values. Perimeter footing drains should be provided for all retaining walls as discussed under the section on Drainage Considerations. It is imperative that proper drainage be provided so that hydrostatic pressures do not develop against the wall. This would involve installation of a minimum 1-foot-wide, washed gravel blanket drain, which is continuous with the perimeter footing drain and extends to within 1 foot of the ground surface. March 13, 20�01 ASSOCIATED EARTH SCIENCES, INC. SGH.�da-KEOIOSSGZ-D:Ixp���3-01 Page 13 Odegard Property Subsurface Exploration, Geologic Hazards, and Proposed Medical Ofjice Building Preliminary Geotechnical Engineering Report Renton, Washington Design Recommendations � , 12.1 Passive Resistance and Friction Factors I! Lateral loads can be resisted by friction between the foundation and the natural glacial soils or supporting structural fill soils, or by passive earth pressure acting on the buried portions of the foundations. The foundations must be backfilled with structural fill, compacted to at least 95 percent of the maximum dry density, to achieve the passive resistance provided below. We recommend the following design parameters: • Passive equivalent fluid = 250 pcf � Coe�cient of friction = .35 The above values are allowable and include a safely factor of at least 1.5. 13.0 ROCKERIES Rockeries may be used to prevent erosion of cut slopes, however, they are not engineered structures, and we strongly suggest that they not be used in place of retaining walls, especially where important facilities are adjacent to them. Buildings should be set back from rockeries so that a 1H:1V line extending up from the rear base of the rockery does not intersect the footing. Rockery construction is an art that depends largely on the skill of the builder. We would like to point out that although rockeries are commonly used, they occasionally have difficulties and should be considered a long-term maintenance item. Care must be exercised in selecting a rock source since some of the material presently being supplied is soft and disintegrates in a relatively short period of time. Samples of rock can be tested by AESI prior to their use in rockeries. It is our understanding that a rockery of up to 10 feet high is proposed to provide erosion control for a planned cut face along the western property boundary. Rockeries over 8 feet in height should be reinforced with Geogridr'" structural fabric and compacted structural fill. If rockeries over 8 feet in height must be constructed at this site, we can provide specific recommendations for GeogridT"' reinforced fill behind the rockery. Medium dense to very dense till and outwash sediments were observed in exploration pits EP-S through EP-7 at depths ranging from 2 to 3 feet below the present ground surface. The I overlying sediments are in a loose condition and the medium dense outwash may contain '� ground water and may not stand at a 1H:1V slope for extended periods. Therefore, the i contractor must be prepared to control ground water seepage and provide stable cut slopes for �', construction of the rockery. Based on the current plans, we anticipate that the base of the � rockery will be placed on the dense to very dense till sediments. I, March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. scyi�-rcEolosscz-o:twp«i3-ot Page 14 Odegard Property Subsurface Fxploration, Geologic Hazards, and Proposed Medical Ofjice Building Preliminary Geotechnical Engineering Repon Renton, Washington Design Recommendalions � The following notes present rockery considerations. A typical rockery detail/sketch is shown in the Appendix. In addition, the contractor should confirm that his configuration conforms with cunent King County specifications. 1. The base of the rockery should be started by excavating a trench to a minimum depth of 12 inches below subgrade into firm, undisturbed ground. If loose, soft, or disturbed materials exist at the base rock location, they should be removed and replaced with free-draining sand and gravel or crushed rock. This backfill material should be compacted to a minimum of 90 percent of the modified Proctor maxunum eensity using ASTM:D 1557 as the standard. The gradation of the sand and gravel should be such, that of the material passing the No. 4 sieve, not more than 5 percent by weight should be finer than No. 200 sieve. 2. The base rock should have a minimum width (perpendicular to the line of the rockery) of 40 percent of the height of the rockery. All rocks should also meet the following weight requirements: Height of Rockery Minirnum Weight of Rock Above 5 feet 500 2200 pounds, graded, top/bottom rocks 5 feet or less 500 1000 pounds, graded, top/bottom rocks 3. The rock material should all be as nearly rectangular as possible. No stone should be used which does not extend through the wall. The rock material should be hard, sound, durable, and free from weathered portions, seams, cracks or other defects. The rock density should be a minimum of 160 pcf. 4. Rock selection and placement should be such that there will be minimum voids and, in the exposed face of the wall, no open voids over 8 inches across in any direction. The rocks should be placed in a manner such that the longitudinal axis of the rock will be at right angles or perpendicular to the rockery face. Each rock should be placed so as to lock into two rocks in the lower tier. After setting each rock course, all voids between the rocks should be chinked on the back with quarry rock to eliminate any void sufficient to pass a 2-inch square probe. The rockery should be limited to 8 feet in height. 5. A drain consisting of rigid, perforated PVC pipe enclosed in a 12-inch-wide pea gravel trench should be placed behind the lower course of rock to remove water and prevent the buildup of hydrostatic pressure behind the wall. The remainder of the wall backfill should consist of quarry spalls with a maximum size of 4 inches and a minimum size of 2 inches. This material should be placed to a 12- inch minimum thickness between the entire wall and the cut material. The March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGN�'da-KE01085G2-D:Iwpldal3-01 Page 15 Odegard Property Subsurface Fxploration, Geologic Hazards, and Proposed Medical Otfice Building Preliminary Geotechnical Engineering Report Reraon, Washington Design Recommendations � backfill material should be placed in lifts to an elevation approximately 6 inches below the top of each course of rocks as they are placed, until the uppermost course is placed. Any backfill material falling onto the bearing surface of a rock course should be rernoved before the setting of the next course. Any asphalt paving should be sloped to drain away from the rockery. In addition, the areas above rockeries should be planted with grass as soon as possible after rockery construction, to reduce erosion. 14.0 FLOOR SUPPORT A slab-on-grade floor may be constructed directly on structural fill or pre-rolled medium dense ground that is not underlain by organic soils. The floor should be cast atop a minimum of 4 inches of washed granulithic material or pea gravel to act as a capillary break. Areas of slab subgrade that are disturbed (loosened) during construction should be compacted to a non- yielding condition prior to placement of capillary break material. The slab should also be protected from dampness by an impervious moisture barrier or otherwise sealed. The impervious barrier should be placed between the capillary break material and a 2- to 3-inch- thick layer of sand. The sand helps to protect the vapor barrier from damage and ailows drainage of the slab during curing. 15.0 DRAINAGE CONSIDERATIONS We recommend construction of a ground water interceptor (cut-of fl drain along portions of the north and west property lines. The drain is intended to intercept shallow ground water flowing toward the on-site wetland from the northwest corner of the site. For preliminary planning purposes, the horizontal extent of drain is expected to be on the order of 300 feet, extending approximately 150 feet south and east from the northwest property corner. However, this length may require modification depending on conditions encountered during construction of the drain and localized intended site use. We recommend the drain be installed prior to construction of the proposed rockery and other improvements. We have included a standard interceptor drain detail in the Appendix. March 13, 2001 ASSOCIATED EARTH SCIENCES,INC. SGH'da-KE01085G2-D:Iwpidnl3-01 Page 16 Odegard Properry Subsurface Exploration, Geologic Hazards, and Proposed Medical O�ice Building Preliminary Geotechnica!Engineering Report Renton, Washington Design Recommendations � When the overlying loose/soft topsoil/fill is removed, the underlying glacial soils will be exposed. The till soils (encountered at 2 feet near EP-7) are relatively impermeable and water will tend to perch atop this stratum. During the earthwork portion of construction, some method should be in place to contain any storm water runoff, remove ponded water from the site, and discharge it to a suitable collection system. Therefore, prior to site work and during construction, the contractor should be prepazed to provide temporary storm and ground water collection, storage, and discharge mechanisms as necessazy. All retaining and footing walls should be provided with a drain at the footing elevation. Drains should consist of rigid, perforated, PVC pipe surrounded by washed pea gravel. The level of the perforations in the pipe should be set 2 inches below the bottom of the footing at all locations and the drains should be constructed with sufficient gradient to allow gravity discharge away from the building. In addition, all retaining walls should be lined with a minimum 12-inch-thick washed gravel blanket provided over the full height of the wall, and which ties into the footing drain. Roof and surface runoff should not discharge into the footing drain system but should be handled by a separate, rigid tightline drain. In planning, exterior grades adjacent to walls should be sloped downward away from the structure to achieve surface drainage. 16.0 PAVEMENT RECOMMENDATIONS Site preparation for areas to be paved should consist of overexcavating to remove the existing vegetation, topsoil, loose/soft upper soils, and any deletarious materials to expose the underlying stable soils. Since the density of the upper soils is variable, random loose/soft areas may exist and the depth and extent of stripping can best be determined in the field by the geotechnical engineer. In addition, along the centerline of pazking areas, the subgrade should be slightly inverted to drain toward the catch basins. After the area to be paved is overexcavated, the exposed ground should be recompacted to 95 percent of ASTM:D 1557. If required, structural fill may then be placed to achieve desired subbase grades. Upon completion of the recompaction and structural fill placement, the recommended minimum pavement section is 2 inches of asphalt concrete pavement (ACP) underlain by 4 inches of 11/a-inch crushed surfacing base course. In delivery truck areas or fire lanes, a minimum 3 inches of ACP and 4 inches of crushed base are recommended. The crushed rock courses must be compacted to 95 percent of the maximum density. March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH/da-KEOIQ85G2-D:Iwpldal3-01 Page 17 Odegard Property Subsurface Exploration, Geologic Hazards, and ` Proposed Medical OtJice Building Preliminary Geotechnical Engineering Report Renton, Washington Design Recommendalions 17.0 PROJECT DESIGN AND CONSTRUCTION MONITORING At the time of this report, final building locations, site grading, structural plans, and construction methods had not been finalized. Therefore, the recommendations presented herein are preliminary. We are available to provide additional geotechnical consultation as the project design develops and possibly changes from that upon which this report is based. We recommend that AESI perform a geotechnical review of the plans prior to final design completion. In this way, our earthwork and foundation recommendations may be properly interpreted and implemented in the design. We are also available to provide geotechnical engineering and monitoring services during construction. The integrity of the foundation depends on proper site preparation and I construction procedures. In addition, engineering decisions may have to be made in the field ' in the event that variations in subsurface conditions become apparent. Construction monitoring services are not part of this current scope of work. If these services are desired, please let us know and we will prepare a cost proposal. We have enjoyed working with you on this study and are confident that these recommendations will aid in the successful completion of your project. If you should have any questions, or require further assistance, please do not hesitate to call. Sincerely, ASSOCIATED EARTH SCIENCES, INC. Kirkland, Washington �• 11d,EP A ,�� �r� W:��,��f.jj�� � � � �"' 'r �'3�'`� �GQ�'�'� _� z � �_� , �.���`.; � � � ,,� � . , � p ,Q 23��0 �j. �v .{� i�n �I' "-c-s� �cs'� "JST�"'v�"! `��`�3`7.�L �-� �""`,�� � EXP1c�c'.� 11 i��!�Z �,.4A-S��6' Susan G. Harrison, P.E. Kurt D. Meniman, P.E. Project Engineer Associate Engineer Attachments: Figure 1: Site and Exploration Plan Appendix: Exploration Logs March 13, 2001 ASSOCIATED EARTH SCIENCES, INC. SGH.-da-KE01085G2-D:'�wpldai3-0l Page 18 � H W a � �� � EP-6 '�.� EP-7"'""` � EP-5 n�ias +e mas ia in�u�c r r �yau � � � EP-8 �EP-9 �,�, �p" EP-4 � � �. . MI dp(p EP-3 �EP-10 °' � � E �EP-1 � za�-o' N � Ag DUVALL AVENUE N.E. (138TH AVE. S.E.) d � �egend o �o so � EP-1 ■ Approximate location of ex loration it FEET � p p Reference: Modawell & Associates � Associated Earth Sciences, Inc. SITE AND EXPLORATION PLAN FIGURE 1 � � � � � � � ODEGARD PROPERTY DATE 03/01 � RENTON, WASHINGTON PROJECT'NO. KE01085G 0 18" MINIMUM , GROUND SURFACE NATIVE BACKFILL � w � FILTER FABRIC-MIRAFI-140 N > OR EQUIVALENT 12"OVERLAP �.� WASHED DRAIN ROCK (ABOVE PEA GRAVEL) � � � � Z d� � v � w � > PEA GRAVEL (MIN 3"SURROUNDING PIPE) I — — — — — — — — Till Till 3"TYP. � � 6" DIAMETER, SCHEDULE 3034 � PERFORATED PVC PIPE TIGHTLINED s TO APPROVED STORMWATER DISCHARGE s SYSTEM (SET PERFORATIONS DOWN) m � � m a 0 � Associated Earth s����«:, i��. TYPICAL INTERCEPTOR TRENCH DETAIL m � � � � � � ODEGARD PROPERTY m RENTON,WASHINGTON 0 0 � LOG OF EXPLORATION PIT NO. EP-1 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that repo�t for complete interpretation.This summary applies only to the I�q6on of this Vench at the � time of excavation.Subsurface condibons may change at this location with the passage of time.The data presented are p a simplfication of actual condiGons encountered. DESCRIPTION Topsoil/Fill Forest duff and loose, black, SILTY SAND with gravel and abundant organics. (SM) 1 2 Recessional Outwash Medium dense,wet, brown, fine to coarse SAND with gravel and cobbles and silt. (SP-SM) 3 Grades to dense at 3'. 4 5 Till 6 Dense to very dense,wet, gray, SILTY fine to coarse SAND with rounded gravel and cobbles. (SM) 7 8 --1Bottom of exploration pit at depth 7 feet Very rapid ground water seepage from 3'-5'. Minor caving from 0-3'. 9 10 11 12 13 � 14 15 16 17 18 19 .,� �� � Odegard Property � � Renton, WA � ASSOCIATED Project No. KE01085G o Logged by: SGH EARTH � Approved by: SCIENCES, INC March 2001 U Y J LOG OF EXPLORATION PIT NO. EP-2 � This log is part of the report prepared by Associated Earth Saences,Inc.(AESI)for the named project and should be � read together with that report for complete interpretation.This summary applies only to the locafion of this trench at the � time of excavation.Subsurface condifions may change at this location with the passage of Lme.The data presented are p a simplficaGon of actual conditions encountered. DESCRIPTION TopsoiUFill Forest duff and loose, moist, black, SILTY SAND with gravel, occasional cobbles, and abundant � organics. (SM) 2 3 Recessional Outwash 4 Medium dense,wet, red-brown, fine to coarse SAND with silt and gravel and cobbles. (SP-SM) Till 5 Dense,very moist, mottled gray,SILTY fine to medium SAND with gravel and cobbles. (SM) 6 7 Becomes very dense, cemented, and moist below 7'. 8 9 10 Bottom of exploraGon pit at depth 10 feet 1 1 Slow ground water seepage from 3'-4'. Slight caving from 0-4'. 12 II '� 13 14 15 16 17 18 19 �� LV � Odegard Property � � Renton, WA � � � ASSOCIATED project No. KE01085G o Logged by: SGH EARTH � Approved by: SCIENCES, INC March 2001 U Y LOG OF EXPLORATION PIT NO. EP-3 x This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be £ read together with that report for complete interpreta6on.This summary applies oniy to the loca6on of this trench at the m time of excavation.Subsurface conditions may change at this loca6on with the passage of�me.The daNa presented are o a simplficaGon of actual conditions encountered. DESCRIPTION . TopsoillFill Forest duff and loose, moist, black, SILTY SAND with gravel, occasional cobbles, and abundant � organics; some brick, plastic, glass, and metal. (SM) 2 Recessional Outwash 3 Medium dense,wet, red-brown, SANDY GRAVEL. (GP) 4 Till Dense to very dense,very moist, gray mottled, SILTY fine to coarse SAND with gravel and 5 occasional cobbles. (SM) 6 Grades to very dense at 6'. 7 Bottom of exp{oration pit at depth 7 feet 8 Very rapid ground water seepage from 2.5'-4'. Slight caving from 0-4'. 9 10 11 12 13 14 15 16 17 18 19 nn LV N Odegard Property m � Renton, WA � � � ASSOCIATED Project No. KE01085G o Logged by: SGH EAF�TH ; Approved by: SCIENCES, INC March 2001 � U Y - LOG OF EXPLORATION PIT NO. EP-4 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report for complete interpretation.This summary applies only to the loca6on of this trench at the m 6me of excavatlon.Subsurface condifions may change at this location with the passage of bme.The data presented are O a simplfication of actual conditions encountered. DESCRIPTION Topsoil/Fili � Forest duff and loose, moist, black, SILTY SAND with gravel and some abundant organics,wood, lass, and metal. SM Fill 2 Loose, moist, brown, SILTY fine SAND with gravel, cobbles, brick, plastic, and glass. (SM) Relict Topsoil 3 Recessional Outwash Medium dense,wet, SILTY fine to coarse SAND with gravel and cobbles. (SM) 4 5 Till 6 Dense,wet, gray, SILTY fine to medium SAND with gravel and cobbles. (SM) 7 Grades to very dense and moist at 7'. 8 Bottom of exploration pit at depth 8 feet 9 Moderate ground water seepage from 3'-6'. Slight qving from 0-4'. 10 11 12 13 14 15 16 I 17 18 19 -,� LV � Odegard Property m � Renton, WA � � ASSOCIATED Project No. KE01085G g Logged by: SGH EARTH � Approved by: SCIENCES, INC March 2001 � U Y = LOG OF EXPLORATION PIT NO. EP-5 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report for complete interpretation.This summary applies only to the location of this Vench at the m time of excavation.Subsurface conditions may change at this location with the passage of t�me.The data presented are o a simplfication of actual conditions encountered. DESCRIPTION Topsoil/Fill � Forest duff and loose, moist, black, SILTY SAND with gravel,cobbles, organics,tires, glass,and paper. (SM) 2 Recessional Outwash 3 Medium dense,wet, red-brown, SANDY GRAVEL with silt and cobbles. (GP-GM) 4 5 Till Dense, very moist, gray, SILTY fine to coarse SAND with gravel and cobbles. (SM) 6 Grades to very dense. 7 Bottom of exploration pit at depth 7 feet 8 Moderate ground water seepage from 2'-4'. Slight caving from 0-3'. 9 10 11 12 13 14 15 16 I� 17 I�� 18 19 �� �� � Odegard Property � � Renton, WA � -, � Lo ed b sGH ASSOCIATED Project No. KEQ1085G 0 99 Y� EAFITH � Approved by: SCIENCES, INC March 2001 � v Y _ _. _ _ -� � LOG OF EXPLORATION PIT NO. EP-6 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report fw complete interpretation.This summary applies only to the location of this trench at the m time of excavation.Subsurface conditions may change at this locabon with the passage of time.The data presented are p a simplfication of actual conditions encountered. DESCRIPTION TopsoillFill Forest duff and loose, moist, black, SILTY SAND with gravei and abundant organics. (SM) 1 2 Fill Loose, moist, red-brown,fine to medium SAND with silt and occasional gravel and cobbles. 3 SP-SM Recessional Outwash 4 Loose, moist, red-brown,fine to coarse SAND with gravei, occasional cobbles, and traces of silt. (SP-SM) 5 Grades to medium dense at 4' 6 Medium dense, wet, brown, SANDY GRAVEL with traces of silt and some cobbles, occasional boulders. (GP} � Grades to dense at 7'. 8 9 Till I 10 Very dense,wet, gray, cemented, SILTY SAND with gravel. (SM) I Bottom of exploration pit at depth 10 feet I � 11 Very rapid ground water seepage from 6'-9'. Slight caving from 6'-9'. 12 I' 13 14 15 16 17 18 I� 19 �� I�I � Odegard Property � N A @ Renton, WA � � � ASSOCIATED Project No. KE01085G o Logged by: SGH EARTH � Approved by: SCIENCES, INC March 2001 � U Y J - LOG OF EXPLORATION PIT NO. EP-7 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report for complete interpretation.This summary applies only to the location of this trench at the � time of excavation.Subsurface conditions may change at this location with the passage of�me.The data presented are p a simplfication of actual conditions encountered. DESCRIPTION Topsoif Weathered Till � Loose to medium dense, moist, brown, SILTY fine SAND with gravel. (SM) 2 Grades to medium dense at 2'. Till 3 Dense, very moist, SILTY fine SAND with coarse sand, gravel, and occasional cobbles interbedded with SAND with silt. (SM/SP-SM) 4 Becomes very dense,moist, cemented, and siltier below 4'. 5 6 Bottom of exploration pit at depth 6 feet 7 No ground water seepage. No caving. 8 9 10 11 12 13 14 15 16 17 18 1g ' nn LV � Odegard Property � � Renton, WA � ' � ASSOCIATED Project No. KE01085G o Logged by: SGH EART�••� � � Approved by: SCIENCES� INC March 2001 I V Y : LOG OF EXPLORATION PIT NO. EP-8 � This log is paR of the report prepared by Assoaated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report for complete interpretation.This summary applies onty to the location of this Uench at the � time of expvation.Subsurface conditions may change at this location with the passage of time.The data presented are o a simplfication of actual conditions encountered. DESCRIPTION Forest duff and Topsoil � Fill 2 Loose, moist, brown, SILTY fine SAND with grave! and occasionai cobbles. (SM) 3 Relict Topsoil Recessional Outwash 4 Loose, very moist, red-brown,fine to medium SAND with gravel, silt, and occasional cobbles. (SP-SM) Grades to medium dense at 4'. 5 6 Medium dense,very moist, gray,very fine SAND with silt, medium to coarse sand, gravel, and occasional cobbles. (SP-SM) 7 8 Till g Dense, very moist, gray, SILTY fine SAND with gravel and occasional cobbles. (SM) �� Very dense and cemented at 10'. 11 Bottom of exploration pit at depth 11 feet 12 No ground water seepage. No caving. 13 14 15 16 17 18 19 �� N Odegard Property � � Renton, WA � � ASSOCIATED Project No. KE01085G ' o Logged by: SGH EARTH � Approved by: SCIENCES, INC March 2001 � U Y J __ � LOG OF EXPLORATION PIT NO. EP-9 � This log is part of the report prepared by Associated Earth Sciences,Inc.{AESI)for the named project and should be � read together with that report for com�lete interpretation.This summary applies only to the location of this trench at the m time of excavation.Subsurface condi'ons may change at this location with the passage of time.The data presented are p a simplfication of actual conditions encountered. DESCRIPTION �' Topsoil/Fill I � Forest duff and loose, moist,black, SILTY SAND with organics. (SM) ! Recessional Outwash 2 Loose to medium dense,very moist, SANDY GRAVEL with traces of silt and some cobbles. (GP) � 3 Grades to medium dense at 3'. 4 Medium dense to dense,wet, brown-gray,fine SAND with silt. (SP-SM) 5 6 � Dense, wet, brown, SANDY GRAVEL with traces of silt and occasional cobbles. (GP) 8 9 � Till? 10 � Very dense,wet, gray, SILTY fine SAND with gravel and occasional cobbles. (SM) ' Bottom of exploration pit at depth 10 feet 11 Very rapid ground water seepage below 4'. Slight caving from 0-7'. 12 13 14 15 16 17 18 19 � � � Odegard Property m � Renton, WA � � ASSOCIATED Project No. KE01085G o Logged by: SGH EARTH � Approved by: SCIENCES� INC March 2001 U Y LOG OF EXPLORATION PIT NO. EP-10 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report for complete interpretation.This summary applies only to the location of this trench at the � time of excavation.Subsurface condisons may change at this loca6on with the passage of time.The data presented are p a simplfication of actuai conditions encountered. DESCRIPTION TopsoiUFiil I � Forest duff and loose,very moist, black, organic, SILTY SAND. (SM) 2 Recessional Outwash 3 Loose,wet, red-brown, fine to medium SAND with gravel and traces of silt and occasional cobbles. (SP) Grades to medium dense at 3'. 4 - - - - - - - - - - - -- -- -- - - - - -- - - - - - - -- - - - -- - - - Dense, SANDY GRAVEL with graces of silt and some cobbles. (GP) 5 6 7 Bottom of exploration pit at depth 7 feet 8 Very rapid ground water seepage from 4'-7'. Slight to moderate caving for the entire depth. 9 10 11 12 13 14 15 16 17 18 19 �� I LV N Odegard Property � � Renton, WA , � � � � ASSOCIATED Project No. KE01085G g Logged by: SGH EARTH � Approved by: sC1ENCES, �NL: March 2001 � U Y LOG OF EXPLORATION PIT NO. EP-11 � This log is part of the report prepared by Associated Earth Sciences,Inc.(AESI)for the named project and should be � read together with that report for compfete interpreta6on.This summary applies onty to the loca6on of this trench at the � time of excavation.Subsurface conditions may change at this location with the passage of Ume.The data presented are p a simplficabon of actual conditions encountered. DESCRIPTION Topsoil � Fill 2 Loose to medium dense, g�ay,fine SAND with silt, gravel, and occasional cobbles. (SP-SM) ; Relict Topsoil 3 Recessional Outwash Medium dense, moist, red-brown,fine to medium SAND with silt, gravel, and occasional cobbles 4 interbedded with SANDY GRAVEL. (SP/GP) 5 6 7 $ Grades to very moist at 8'. 9 Grades to dense,wet, gray,fine SAND with silt,gravel, cobbles, and lenses of silty fine sand. (SP-SM) 10 Till? �� Very dense,wet, gray, GRAVELLY, SILTY SAND. (SM) 12 Bottom of exploration pit at depth 12 feet 13 Rapid ground water seepage below 9'. No caving. 14 15 16 17 18 19 �� N Odegard Property � � Renton, WA � � ASSOCIATED project No. KE01085G o Logged by: SGH EARTH � Approved by: SCIENCES� INC March 2001 V Y I � ROCKERY DETAILS �� � (NOT TO SCALE) No rwdway, parkinq lots or building footings in this area 3 (or flatter) i 1' min. � �i . � oDOoo /�i i (min.16') oO,Q� � i 6 0�00°o iQ1 o�oo° �/ 1 Dopo i� op o i 0 0 �°p0oo i� Hei9ht o O�p �i / Min. 1 foot wide layer of 2'-4' qua�ry o �, spalls. �cent to rockery (msx. 8') O° o � - opo0 / O�p�Q' i 0 0 0,o Stable cut face in natural material O Oo see note 5 00 � o . �f � ���� ; °0$0 i� 1" (or less) diameter washed gravel; min. 12 inches i� min. 6" cove► over pipe; mi� Y --- ------- — gravel under pipe Firm, undisturbed soil Min. 4' diam. perf. rigid PVC pipe; see note 2 min. 1X continous slope to outlet. NOTES: ' ', 1. Rockeries higher than 5' shall be constructed of rocks of graduated sizes ! from 5-man to 2-man from bottom to top. Rockeries of 5' or lower shall be constructed of 3-man to 2-man from bottom to top. 2. Inspection of subgrade, placement of base course and drainage, and finished ± rockery by geotechnical engineer is required. � 3. Rock shall be sound and have a minimum density of 160 pounds per cubic foot. 4. The long dimension of all rocks shall be placed perpendicular to the wall. � Each rock should bear on two rocks in the tier below. . 5. Rockeries are erosion-control structures, not retaining walls. Natural � material must be stable and free-standing in cut face. Maximum height of � 3 feet for rockeries facing fill soils. � Rock LB. � i 1 man 100-300 2 man 300-800 3 man 800-1500 ; � 4 man 1500-2200 5 man 2240-4000 t TYPICAL ROCKERY DETAILS ASSOCIATED EARTH ODEGARD PROPERTY SCIENCES, INC s ' RENTON, WASHINGTON PROJECT NO. KE01085G -