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HomeMy WebLinkAboutG95072A SUBSURFACE EXPLORATION AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT RIBERA 28 ACRES RENTON, WASHINGTON PREPARED FOR Centex Homes PROJECT NO. G95072A JUKE 1995 ASSOCIATED EARTH JA�ZMSCIENCESq INC 911 - 5th Avenue, Suite 100, Kirkland, WA 98033 (206) 827-7701 FAX (206) 827-5424 SUBSURFACE EXPLORATION AND PRELIMINARY GEOTECHNICAL ENGINEERING REPORT RIBERA 28 ACRES RENTON, WASHINGTON June 6, 1995 Project No. G95072A I. PROJECT AND SITE CONDITIONS 1.0 INTRODUCTION This report presents the results of our subsurface exploration and preliminary geotechnical engineering study for the proposed residential development of the Ribera 28 acres. Our geotechnical recommendations are preliminary in that building locations and construction details were not available at the time of our study. We understand that Centex wishes to purchase the property for the purpose of constructing single family residences. The location of the property is shown on the attached vicinity map, Figure 1. The approximate locations of the subsurface explorations accomplished for this study are shown on the site and exploration plan, Figure 2. In the event that any changes in the nature of the project are planned, 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 for the evaluation, design and construction of the future development of the Ribera project. The study included a review of available geologic literature, and the excavation of exploration pits to assess the type, thickness, distribution and physical properties of the subsurface sediments and shallow ground water conditions at the site. Geotechnical engineering studies were also conducted to determine the types of suitable foundations, floor support recommendations, allowable foundation soil bearing pressures, as well as structural fill, pavement and drainage considerations. This report offers development recommendations based on our understanding of the future development of the property. 1.2 Authorization Written authorization to proceed with this study was granted by Mr. Kevin Simmons of Centex Homes, in a proposal dated March 21, 1995. This report has been prepared for the exclusive use of Centex Homes and their agents, for specific application to this project. Within the limitations of scope, schedule and budget, our services have been performed in accordance with accepted geotechnical engineering and engineering geology practices in effect in this area. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are a means to identify and reduce the inherent risks to the owner. 2.0 PROJECT AND SITE DESCRIPTION This report was completed with an understanding of the project based on a site map dated May 4, 1995 prepared by Hugh G. Goldsmith and Associates, and a U.S. Geological Survey (USGS) topographic map of the Renton Quadrangle. The subject site was located along the north side of SE 128th Street, between 148th Avenue SE and 152 Avenue SE in Renton, Washington. The property was rectangular in shape and measured 1925 feet north-south by 655 feet east-west, less a 337-foot by 125-foot parcel removed from the southwest corner of the site (Figure 2). The south side of the property bordered SE 128th Street, the east side bordered pasture, and the west and north sides bordered undeveloped wooded land. A few residential homes were present along the west central border of the site, and on the parcel at the southwest corner of the property. An existing home, with sheds and a driveway to SE 128th Street, was present in the southeastern portion of the property. Two overhead power lines ran along the south side of the site. Outside of these features, the site was undeveloped. Most of the property was covered by dense stands of alder and cottonwood trees with a thick understory of brush, berry bushes, small saplings and ferns. Prior to our study, wetlands had been delineated in the northeastern and southwestern portions of the property. A crude dozer trail had been cut along most of the perimeter of the site, and overgrown logging trails were present in the central portion of the property. The overall site was relatively flat, but the southwestern portion of the property sloped gently down to the southwest. A poorly developed drainage swale, with less than 15 feet of relief drained to the south in the southwestern portion of the property. A south-flowing drainage ditch was also present along the west central boundary of the property, adjacent to the residential homes. Total topographic relief of the site was less than 25 feet. Development plans were not available at the time of our field study. 3.0 SUBSURFACE EXPLORATION Our field study consisted of excavating a series of 17 exploration pits, utilizing a track-mounted excavator. The pits permitted direct, visual observation of subsurface conditions. The materials encountered were studied and classified in the field by an engineering geologist from our firm. Selected samples were then transported to our laboratory for further visual classification and testing, as necessary. The exploration pits were backfilled immediately after examination and logging. The various types of sediments as well as the depths where characteristics of the sediments changed are indicated on the exploration logs presented in the Appendix. Our explorations were approximately located in the field by measuring from known site features shown on Figure 2. 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 sometimes may be present due to the random nature of deposition and the alteration of topography by past grading and filling. The nature and extent of any variations between the field explorations may not become fully evident until construction. If variations are observed 2 at that time, it may be necessary to re-evaluate specific recommendations in this report and make appropriate changes. 4.0 SUBSURFACE CONDITIONS Subsurface conditions were inferred from the exploration pits, and a visual reconnaissance of the site. This study identified dense glacial sediments at shallow depths across the property. In the area of the existing residence, fill soils (those not naturally placed) could also be present in drain field area(s) and utility trenches. The stratigraphy of the site is discussed in the following section followed by our observations of the hydrology of the site. 4.1 Stratigraphy Fill soils were not encountered in any of the exploration pits, but could to be present in the area of the existing residence. The developed area (home) is minor in total area and was not explored by this study. The quality, thickness and compaction of the fill materials may be variable and is undocumented. Therefore, if fill is encountered during construction at the site, it should be considered unsuitable for foundation support. At the surface across the site (beneath a 6-inch- to 2-foot-thick topsoil/organic zone) all 17 of the exploration pits encountered loose to medium dense, moist to wet, yellow brown, mottled, gravelly silty sand, interpreted as weathered till. This weathered zone extended to depths ranging from 2 feet in EP-2, EP-3, EP-7, EP-10, and EP-17, to 3-1/2 feet in EP-1 and EP-5. Beneath this mottled sediment, all of the exploration pits encountered dense, brownish gray, silty sand with gravel, interpreted as lodgement till. The lodgement till extended to below the 7- to 13-foot termination depths of all of the exploration pits. The lodgement till is highly consolidated sediment that was deposited at the sole of an advancing glacial ice sheet. In the Renton area the ice sheet reached an estimated thickness of 3,000 feet, during the Vashon Stade of the Fraser Glaciation about 15,000 years ago. As a result of glacial consolidation (by the weight of the ice), this material possesses high strength, low compressibility, and comparatively low permeability. 4.2 Hydrology No flowing water was observed at the site. Minor standing water was observed in areas mapped as wetland, and in the drainage swale in the southwestern portion of the site. Evidence of temporary standing water was also observed in dried mud puddles in a number of areas near the wetlands. We would expect that most, if not all of these puddles, are the result of precipitation perching atop the relatively impermeable till sediments. Light ground water seepage was encountered in about half of the exploration pits, at depths ranging from near the surface to about 3 feet deep. Moderate seepage was encountered from 2 to 4 feet in EP-10, from 0 to 2-1/2 feet in EP-11, and from 1 to 2-1/2 feet in EP-12. Rapid seepage was also present in a localized zone at 1-1/2 feet in EP-12. The seepages encountered occurred atop and within the mottled, weathered till zone. 3 Fluctuations in the level of the ground water, and subsequent seepage activity can be expected due to the time of the year and variations in rainfall. We would expect that nearly all of the seepage activity encountered is the result of on-site precipitation perching atop and within the weathered lodgement till. 4 June 6, 1995 Project No. G95072A II. PRELIMINARY DESIGN RECOMMENDATIONS 5.0 INTRODUCTION In our opinion, from a geotechnical standpoint, the site is suitable for a residential development, based on the site exploration and visual reconnaissance. A suitable foundation bearing stratum, consisting of lodgement till, occurs near the surface and will be capable of providing foundation support. Conventional spread footing foundations, slab-on-grade floors, and pavement subgrades, may be supported on the natural bearing sediments, or on structural fill that overlies natural bearing sediments. The contractor should understand that although the bearing stratum was relatively shallow in our exploration pits, areas exist that may contain loose soil. In addition, filled areas may be encountered in the vicinity of the existing residence, utility trenches, or drain fields. These areas may require deepened footings or removal and replacement of the loose soil or fill material with structural fill prior to placing foundations. We should further emphasize that the site is underlain by fine-grained, moisture sensitive soils, which were at or above their optimum moisture content for use as structural fill. Therefore, the use of the onsite lodgement till soil as structural fill should be limited to the drier times of the year. 6.0 SITE PREPARATION Site preparation of planned building and road/parking areas should include removal of all trees, brush, debris and any other deleterious material. Additionally, the upper organic topsoil should be removed and the remaining roots grubbed. Areas where loose surficial soils exist should be considered as fill and this material should either removed and replaced with structural fill or recompacted. Since the density of soils is variable, random soft/loose pockets may exist, and the depth and extent of stripping can best be determined in the field by the field engineer. Site preparation will also include the demolition of the existing structure. The debris from this operation should be taken to an offsite disposal area and any resulting depression, if beneath a building or road area, should be replaced with structural fill. Existing septic tank(s) should also be removed, and the resultant depression replaced with structural fill. All other areas where loose surficial soils exist should be considered as fill and this material should either removed and replaced with structural fill or recompacted to the specified project densities. 5 7.0 STRUCTURAL FILL All fill should be placed in accordance with the recommendations outlined in this section. Prior to filling, topsoil, organics, and loose soils should be excavated from the subgrade as advised by the field engineer. After overexcavation/stripping has been performed to the satisfaction of the geotechnical engineer, the upper 12 inches of exposed ground should be recompacted to at least 90 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. After recompaction of the exposed ground is tested and approved, 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. The contractor should note that any proposed fill soils must be evaluated by Associated Earth Sciences, Inc. prior to their use in fills. 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. The onsite lodgement till soils contain a significant amount of fine-grained material (smaller than No. 200 sieve) and are considered extremely moisture-sensitive. Use of moisture- sensitive soil in structural fills should be limited to favorable dry weather conditions. If fill is placed during wet -weather or if proper compaction cannot be obtained, clean, free-draining gravel and/or sand should 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. 8.0 FOUNDATIONS Spread footings may be used for building support when founded on the medium dense to dense natural glacial sediments, or approved structural fill (including recompacted natural soils). For building support, structural fill and recompacted natural soils should be compacted to a minimum of 95 percent of the maximum dry density as defined by ASTM:D 1557. Structural fill placement must be inspected by Associated Earth Sciences, Inc. to verify suitable subgrade preparation and compaction. We recommend that an allowable bearing pressure of 2,000 pounds per square foot (psf) be utilized for design of residence footings, including both dead and live loads. An increase of one- third may be used for short-term wind or seismic loading. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection; interior footings require only 12 inches burial. However, all footings must penetrate to the prescribed lodgement till bearing stratum and no footing should be founded in or above loose, organic, or existing fill soils. 6 9.0 FLOOR SUPPORT Slab-on-grade floors may be placed over the medium dense to dense natural sediments or approved structural fill. In either case, the upper 12 inches of subgrade must be compacted to a minimum of 90 percent of the modified Proctor maximum density as determined by ASTM:D 1557. A polyethylene plastic vapor barrier and pea gravel capillary break layer should be used under floors likely to receive an impermeable floor finish or where passage of water vapor through the floor is undesirable. Based on American Concrete Institute recommendations, we suggest placing a two to three inch layer of clean sand over the vapor barrier to protect the vapor barrier and to allow some moisture loss through the bottom of the slab to aid in the curing process. Sand should be used to aid in the fine grading process of the subgrade to provide uniform support under the slab. 10.0 DRAINAGE CONSIDERATIONS At the site, the lodgement till sediments are near the surface. These sediments contain a significant amount of fine grained material, and are considered moisture sensitive. Because the till is relatively impermeable, water will tend to perch atop this stratum. Traffic across the till sediments when they are damp or wet will result in disturbance of the otherwise firm stratum. Therefore, prior to site work and construction, the contractor should be prepared to provide drainage and subgrade protection as necessary. All retaining and perimeter 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 approximately 2 inches below the bottom of the footing and the drains should be constructed with sufficient gradient to allow gravity discharge away from the buildings. In addition, 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 systems but should be handled by a separate, rigid tightline drains. Because the site does not contain free-draining soils, exterior grades adjacent to walls must be designed to slope downward away from the structures to achieve positive surface drainage. 11.0 PAVEMENT CONSIDERATIONS Areas to be paved should be compacted to a firm, unyielding condition to a minimum of 95 percent of the modified Proctor maximum density using ASTM:D 1557 as the standard. The subgrade surfaces should be slightly crowned to drain to the edges of the paved areas. After compaction, the subgrade should be proof-rolled with a fully loaded, tandem axle dump truck to identify any soft or "pumping" areas. If such areas are observed, they should be overexcavated and backfilled with compacted, free-draining, granular material. Upon completion of the subgrade preparation the leveling course and surface pavement may be placed. The appropriate pavement section will be determined by the anticipated traffic loads and 7 desired pavement life. The pavement base leveling course material should be compacted to 95 percent of Maximum Density as defined by ASTM:D 1557. 12.0 PROJECT DESIGN AND CONSTRUCTION MONITORING At the time of this report, site grading, structural plans, and construction methods have not been completed. 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 Associated Earth Sciences, Inc., 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 foundations depends on proper site preparation and 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 vG� B'L \V A�fi,,, ���� ti . z �. F c George Bennett, C.P.G. 61 7/y5' Engineering Geologist 26880 `� SSIONAL FrG EXPIRES 53 -7 y6 T.A. Parker, P.G. Bruce L. Blyton, P.E. Principal Senior Engineer GHB/kpp G95072A.I WP.6/1/95 Id 8 �, i 1 I ��� I 19011) i— , � U k'?pf - - t ! SITE �- i - /� rave �- � •�o�Cs I Mapl l64j':.:_ •. �� � �Heig � I r �A a'ira4fk r _ y� - Indiaq — I � `._t A. 167 St f I aver — \ `✓�� \ f.fV j i 31 �`, W , 3 11 P+n4 ::: ;'rve t1:s� 1 te1 1 . Pit vq. f\ L Radl -- Fact 0 1=J pmr g :iii C:rrn t g�—= i I LbkrO v .Wer i� I P� arr_t r Tama— sla � - LL L14w _ rokee K. ,�1J _ \ m I 1 '�. `I oviagton 3I/ r / 1 LL I _ g eaitlf _ ,z. f'. REFERENCE: U.S.G.S. 1:100,000 SCALE METRIC TOPOGRAPHIC-BATHYMETRIC MAP 30 X 60 MINUTE QUADRANGLE -TACOMA, WASHINGTON•. VICINITY MAP NORTH RIBERA - 28 ACRES ABSOCIATED I RENTON, WASHINGTON EARTH8 C I E N C E 8, I N C G95072A 5/95 FIGURE 1 EP-9 EP-10/ -� WETLAND tB"/ EP-8 S E7-11, WETLAND tA� EP-13 ■ EP-7 EP-12 EP-15 IN EP-6 EP-1� ■ ail WETLAND "D" C� EP-1 6 ? �WETLAND "E" EP-5� EP-17 WETLAND "F" i EP-4 EP-1 ■ EP-3 ■ ■ EP-2 ■ SE 128th St. LEGEND NORTH ■ Approximate location of exploration pit 0 300 600 SCALE IN FEET SITE AND EXPLORATION PLAN RIBERA - 28 ACRES ASSOCIATED RENTON, WASHINGTON42M EARTH SCIENCES, INC I 1335072A 5/95 FIGURE 2 EXPLORATION PIT LOG 0 _Number EP-1 1"Topsoil and oxidized zone. Medium dense to dense, moist, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 Very dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) 10 BOH @ 8-1/2' Note: Light seepage at 3-1/2'; no caving. Terminated due to hard digging. 15 0 _Number EP-2 6"Topsoil. Loose, moist, dark yellow-brown, gravelly, silty, fine SAND. (Weathered Lodgement Till) Dense, moist, brown-gray, mottled on top 1-1/2', gravelly, silty SAND. (Lodgement Till) 5 BOH @ 8' 10 _ Note: Very light seepage at 3-1/2'; no caving. 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 1 Fax- 206-827-542' MC-) 1995 EXPLORATION PIT LOG 0 _Number EP-3 6"Topsoil. Loose to medium dense, moist, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) _ Dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) 5 BOH @ 8' 10 _ Note: No seepage; no caving. Terminated due to hard digging. 15 0 _Number EP-4 6"Topsoil. - Loose, moist, dark yellow-brown, gravelly, silty SAND with many roots. (Weathered Lodgement Till) 5 Dense to very dense, moist, brown-gray, mottled to 4', gravelly, silty SAND. (Lodgement Till) 10 BOH @ 12' Note: Very light local seepage 4' to 6'; no caving. Terminated due to very hard digging. 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. 1 I Reviewed ByI Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 Fax: 205-827-5424 May 1995 EXPLORATION PIT LOG 0 _Number EP-5 - 8"Topsoil/root zone. Loose to medium dense, moist, dark yellow-brown, gravelly, silty, fine SAND with many roots. (Weathered Lodgement Till) 5 Dense to very dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) BOH @ 8' 10 Note: No seepage; no caving. 15 0 Number EP-6 Black topsoil. - Soft/loose, wet to saturated, yellow-brown, gravelly sandy SILT to silty SAND. (Weathered Lodgement Till) 5 Dense, moist to wet, brown-gray, gravelly, silty SAND. (Lodgement Till) 10 BOH @ 10' Note: Light seepage throughout 1'to 3'; no caving; light sloughing at seepages. 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By 4L Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 FLx- 20C3-827 ;2 " May 1995 EXPLORATION PIT LOG 0 _Number EP-7 6" Topsoil. Loose, moist, dark yellow-brown, gravelly, silty, fine SAND, many roots. Loose to medium dense, moist yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 Dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) BOH @ 8' 10 — Note: No seepage; no caving. 15 0 Number EP-8 10"Topsoil/root zone. - Loose to medium dense, moist, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 — Dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) 10 BOH @ 9' Note: Very light local seepage at 2-1/2'; no caving. 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other limes and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 Fax: 206-827-5424 May 1995 EXPLORATION PIT LOG 0 _Number EP-9 6"Topsoil. - Loose, moist, dark yellow-brown, silty, fine SAND, some gravel, roots. - Medium dense, moist, light yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 _. Dense to very dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) 10 BOH @ 8-1/2' Note: No seepage; no caving. 15 0 _ Number EP-10 Soft, saturated, dark gray, organic rich, silty, fine SAND, some gravel. 5 Dense, moist to wet, light brown-gray, mottled to 4', gravelly, silty SAND. (Lodgement Till) BOH @ 8' 10 _ Note: Light to moderate seepage 0-4'throughout; light sloughing at seepages, no caving. 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 Fax- 20ro-827-5424 May 1995 EXPLORATION PIT LOG 0 _Number EP-11 Topsoil/muck. - Loose to medium dense, saturated, light yellow-brown, gravelly, silty SAND. (Weathered Lodgement Till) -5 Dense to very dense, moist to wet, brown-gray, gravelly, silty SAND. (Lodgement Till) _ BOH @ 7' Note: Rapid local seepage piping at 1-1/2; moderate seepage 0 to 2-1/2'; some caving 0 to 2412'at -10 seepages. 15 0 Number EP-12 Topsoil/muck. Loose to medium dense, saturated, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 _ Dense to very dense, moist to wet, gray, gravelly, silty SAND. (Lodgement Till) 10 15 BOH @ 13' Note: Light to moderate seepage V to 2-1/2'throughout; no caving. Very hard digging. Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By ( � Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 _`7-544_ May 1995 EXPLORATION PIT LOG 0 _ Number EP-13 6"Topsoil. Loose to medium dense, moist, dark yellow-brown, silty, fine SAND with some gravel, many roots. (Weathered Lodgement Till) 5 Dense to very dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) BOH@7' Note: No seepage; no caving. Very hard digging. 10 15 0 _Number EP-14 8"Topsoil. Loose to medium dense, moist, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 _ Dense to very dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) BOH @ 7' Note: No seepage; no caving. 10 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 Fax: 20G-827-542/ May 1995 EXPLORATION PIT LOG 0 Number EP-15 10"Topsoil/root zone. Loose to medium dense, moist, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 _ Dense to very dense, moist to wet, gray, gravelly, silty SAND. (Lodgement Till) BOH@8' 10 — Note: No seepage; no caving. 15 0 Number EP-16 10"Topsoil/root zone. Loose to medium dense, moist to wet, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 Dense to very dense, moist to wet, gray, gravelly, silty SAND. (Lodgement Till) BOH @ 8' 10 Note: No seepage; no caving. 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 F2x: 206-827-�424 Mpy 1995 EXPLORATION PIT LOG 0 _ Number EP-17 3"Sod/topsoil. Loose to medium dense, moist, yellow-brown, mottled, gravelly, silty SAND. (Weathered Lodgement Till) 5 Very dense, moist, brown-gray, gravelly, silty SAND. (Lodgement Till) BOH @ 8' 10 Note: No seepage; no caving. 15 0 Number 5 10 15 Subsurface conditions depicted represent our observation at the time and location of this exploratory hole,modified by geologic interpretation,engineering analysis,and judgment. They are not necessarily representative of other times and location. We will not accept responsibility for the use or interpretation by others of information presented on this log. Reviewed By ,, Associated Earth Sciences, Inc. Ribera - 28 Acres 911 Fifth Avenue, Suite 100 Renton, Washington Kirkland, Washington 98033 Project No. G95072A Phone: 206-827-7701 Fax: 206-827- 5--^124 May 1995 .. . . . .. _, III . -- I , II ' � . !. lI Cl �'� ( l [_ �_.� 1__I � . � , . 1- � , � � [C1 � . �l