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HomeMy WebLinkAbout03333 - Technical Information Report - Geotechnical GEOTECHNICAL ENGII�TEERTi�TG REPORT I Pro osed Rainier Ave. Mixed Use Pro'ect �I P J 559 to 625 Rainier Ave. North Renton, Washington Project No. 2002-062B ', Prepared By: The Riley Group, Inc. �, 10728 Lake City Way NE Seattle, WA 98125 Prepared for: JDA Group, LLC 95 South Tobin Street �, Renton, «'ashington 98055 �I DEVEl7PMENT PLANNING II� June 2, ?003 CITY OF RENTON , NOV 0 4 2004 �'�� RECEIVED '� � June 2, 2003 JDA Group, LLC 95 South Tobin Street Renton, Washington 98055 Attn: Mr. Jack Alhadeff Subject: Geotechnical Engineering Report Proposed Rainier Ave. Mixed Use Project 559 to 625 Rainier Ave. North Renton, Washington Project No. 2002-062B The Riley Group, Inc. (Riley) has completed a geotechnical engineering study for the � above referenced project. This report summarizes our findings and recommendations for the geotechnical aspects anticipated for the project design and construction. We tpreviously completed an evaluation of the nature and origin of the steep slopes on the site, and summarized the results of our work in our letter dated October 29, 2002; and we completed a preliminary evaluation of slope stability and summarized the results of our work in our letter dated June 8, 2001. PROJECT DESCRIPTION In preparation of this report, we reviewed site plans provided by Rich Wagner of Baylis Architects on February 13 and April 1, 2003, and discussed the project with him several times. We have reviewed several E-mails (sent in February 2003) from the City of Renton to Rich Wagner and/or Jack Alhadeff. Our understanding of the project is based on that information. Geotechnical Engineering Repert June 2, 2003 Proposed Rainier Ave. Miaed Use Project Project No. 2002-062B � Renton,Washington Page 2 of 45 !, Pro�ect Understandin� The site is located at 559 to 625 Rainier Ave. North in Renton, Washington, as shown on the Site Vicinity Map, Figure 1. Existing buildings and proposed buildings are shown on the Site and Exploration Plan, Figure 2. Existing topography and existing buildings are shown on the Topographic Site Plan, Figure 3. We understand it is proposed to construct a mixed-use project that will include commercial development and private housing. These are considered to be 2 separate projects. Commercial Development Project The commercial development project will be in the level area adjacent to (on the west side o�Rainier Ave., and will include the following elements. 1. Building 1 (north side of site) 100 feet by 80 feet footprint, 3 story 2. Building 2 (center of site) 100 feet by 75 feet footprint, 2 story 3. Building 3 (south side of site) 130 feet by 70 feet footprint, 2 story 4. Parking Structure{west side of site) 250 feet by 60 feet, 2 levels, 1 below grade ' S. Retaining wall (between Bldg. 2 & 3) about 12 feet tall by 170 feet long ' All of these are currently located such that they cut into the toes of existing steep slopes. We assume that foundation loads for the commercial buildings will not exceed about 5 kips per linear foot for continuous wall footings and 200 kips for isolated column footings. Housing Project The housing project will be located on the west side of the site, east of the cul-de-sac at NW 6th Street, at the top of a steep slope down to the commercial area. There are 16 dwelling units planned, in a configuration of either 6 or 4 buildings. The units will require cuts into the existing top of slope of up to 9 or 10 feet. Also, some fill will be THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 3 of 45 placed on the east-facing slope (in a topographic trough along a utility easement), and will require retaining structures. We assume that foundation loads for the residential structures will not exceed about 2 kips per linear foot for continuous wall footings and 50 kips for isolated column footings. The recommendations in the following sections of this report are based on our understanding of the design features described above. If actual features vary or changes are made, we should review them in order to modify our recommendations as required. In addition, we recommend that we be retained to review the final design drawings and specifications to verify that our project understanding is correct, and that our recommendations have been properly interpreted and incorporated into project design and construction. BACKGROUND The City of Renton Development Services Division expressed concern about the project with regard to slope stability. Specifically, there have been landslides north of the site, at NW 7th Street and Taylor Ave. NW. The City requested a geotechnical report for this project that meets the following requirements (based on an E-mail from Gregg Zimmerman [City of Renton], to Rich Wagner, dated 06 Feb 2003, at 09:10). 1. Incorporates a complete historical perspective of slide activity in the vicinity of this site 2. Incorporates the information from previous geotechnical analyses done for this vicinity by the City 3. Specifically addresses features of the current development proposal 4. Identifies and characterizes the types of geotechnical problems that exist on the ' site and how these problems might be impacted by the proposed development I 5. Analyzes the aforesaid geotechnical conditions and the development proposal ' and makes specific recommendations regarding how such a development could be constructed in a safe manner both for the development itself and for uphill �, THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave. Miaed Use Project Project No. 2002-062B Renton,Wasiungton Page 4 of 45 and downhill properties (such recommendations to include such design features as construction methods, set backs, foundation systems, stabilizing/retaining structures that would be needed, drainage requirements, etc.) We also understand that the City would like the report to address the slopes to the north and south of the site, as well as the "central" slope (based on an E-mail from Lesley Nishihira [City of Renton], to Bill Kuck, dated 14 February 2003, at 12:18). References/Information Provided by the Citv of Renton The City of Renton (Lesley Nishihira) provided us the following reports of previous geotechnical analyses done for this vicinity. Reports 1, 2, and 3 were done for the City; reports 4 and 5 were done for private individuals. 1. GeoEngineers; May 16, 1991; "Preliminary Geatechnical Evaluation, Landslide , and Broken Sewer Lines, Slope West of Rainier Avenue North, Renton, Washington"; for City of Renton 2. GeoEngineers; October 4, 1991; "Report, Supplemental Geotechnical ��i Engineering Services, Sewer Line Reconstruction and Slope Stabilization, Slope �' West of Rainier Avenue North, Renton, Washington"; for City of Renton ! 3. GeoEngineers; November 6, 1997; "Report, Geotechnical Engineering Services, Sewer Line Reconstruction, Rainier Avenue North and NW 7th Street, Renton, Washington"; for City of Renton 4. Geo Consultants; May 8, 1991; "Slope Failure Study, Mr. Chester Rindfuss' Residence, 676 Taylor Avenue Northwest, Renton, Washington"; for Mr. Chester Rindfuss 5. Geo Group Northwest; February 18, 1993; "Slope Stability Analysis and Landslide Stabilization Design, 676 Taylor Avenue Nti'�', Renton, �'ashington"; for Mr. John McFarland THE RILEY GROUP, INC. - Geotechnical Engineering Report June 2,2003 'I Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 5 of 45 References/Information From Previous Work by Riley We also used information from previous work completed by Riley for the project site. This information included the following letters. 6, The Riley Group; June 8, 2001; "Preliminary Slope Stability Study, Meyer Property, 559 to 625 Rainier Avenue North, Renton, Washington"; for Mr. Jack Alhadeff 7. The Riley Group; October 29, 2002; "Slope Evaluation, Rainier Ave. Mixed Use Project, 559 to 625 Rainier Ave. North, Renton, Washington"; for Mr. Jack Alhadeff - SCOPE OF SERVICES The purpose of our work was to explore and characterize the subsurface soil and ' groundwater conditions, and develop geotechnical recommendations for design and construction of the proposed project. This included complying with the requirements of the City of Renton listed above. Based on the project understanding and background discussed above, our scope of sen�ices included the following tasks. 1. Collect and review readily available information on historical slide activity in the area. 2. Research and review readily available geotechnical studies done by the City in the area. 3. Identify features of the currently proposed development that have geotechnical significance. 4. Complete a subsurface exploration program with borings and test pits to characterize subsurface soil and groundwater conditions 5. Identify and characterize types of geotechnical problems that exist on site, and evaluate how these problems might be affected by the proposed development. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 6 of 45 6. PerForm engineering analyses and/or develop recommendations regarding the items listed below. a) Slope stability for those slopes directly affected by the project, and for adjacent slopes. b) Construction methods. c) Setbacks from top and toe of slopes. d) Retaining structures. e) Foundations for buildings. � Drainage. g) Seismic design considerations, including site seismicity, Uniform Building Code (UBC) Soil Profile Type,__liquefaction potential, and potential liquefaction-induced settlement. h) Site preparation and earthwork, including excavation, subgrade preparation, I suitability of onsite soils for use as construction materials, fill placement, ' iallowable cut and fill slopes, and potential necessity for dewatering during ,I construction. � I I i) Design pavement section. I - ,I ' 7. Prepare a report summarizing the results of our work. i SURFACE CONDITIONS Existin conditions are shown on Fi ure 3. The site e�ends about 750 feet north-south �I g g '� along the west shoulder of Rainier Ave. North. At the NW 6th Street cul-de-sac, the site extends about 370 feet to the west of Rainier Ave. North. There are 3 slopes in the project vicinity, defined as follows for the purpose of this report. • The "north slope" starts at the north end of the site and continues north; its south- , facin ortion is ad'acent to Buildin 1. gP J g �I I ' i THE RILEY GROUP, IN�. I Geotecluucal Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 7 of 45 • The "central slope" surrounds the cul-de-sac at NW 6th Street; its east-facing portion is adjacent to Buildings 2 and 3 and the retaining wall in between them. • The "south slope" is south of the central slope, and is off of the project site; its north-facing portion is over 100 feet away from the proposed development. At the time of our field explorations, there were 3 buildings in the proposed commercial development area of the site. The ground surface was relatively level and flat, at about Elevation 50 feet (NAVD '88 Datum). Most of the site along Rainier Ave was paved with asphalt. Farther to the west there was some gravel surfacing with sparse grass, and some grassed areas. Between the level area and the NW 6th Street cul-de-sac was a steep slope ("central slope"} up to the west that rose from Elevation 50 feet to Elevation SO or 90 feet at average inclinations ranging from about 1.3 horizontal to 1 vertical (1.3H:1V} to 1.7H:1 V. There was a gully down the face of this east-facing slope associated with a utility easement where there apparently were 12-inch and 4-inch diameter water lines and an 8-inch diameter sanitary sewer. From the top of slope there was a gentle slope up to the west to about Elevation 1 OS feet at about a l OH:l V slope. North and south of this upper area were slopes down to the north and south (respectively} at about 1.7H:1 V. These slopes led to partially filled in ravines that trended west to east, sloping down to the east. The slopes were well vegetated with trees and brush. The slope south of the site ("south slope") sloped down to the north at about 1.SH:1 V. The slope was well vegetated with trees and brush. '� i_ I The slope on the north side of the site ("north slope") had south-facing and east-facing ' _ slopes. Top of slope was about Elevation 100 feet. The south-facing slope sloped I', - down to the commercial development area at about 1.SH:1V. The slope was well II I '� I _ vegetated with trees and brush. The east-facing slope sloped down to Rainier Ave. at THE RILEY GROUP, INC. Geotechnical Engineering Report June 2, 2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 8 of 45 about 1.3H:1 V to 1.7H:1 V. The northern part of this east-facin� slope was where there have been stability problems in the past. SUBSURFACE CONDITIONS Field Explorations Subsurface conditions were explored with 4 borings and 12 test pits completed in April 2003. We also considered 2 monitoring wells that were installed by Riley on March 19, 2001. The approximate locations of all the explorations we considered are shown on the Site and Exploration Plan in Figure 2. The test pits (TP-1 through TP-12) were excavated April 7 to 11, 2003, to depths of about 4 to 14 feet below the existing ground surface, with a rubber-tired Case 580E backhoe equipped with an extendahoe. TP-1 through TP-5 were located on the central slope, and TP-6 through TP-12 were located in the lower, level area. The borings (B-1 through B-4) were drilled to depths of about 18 to 54 feet below the ' existing ground surface by a subcontractor using a track-mounted Mobile B-53 drill rig (B-1, B-2, B-3) or a truck-mounted Mobile B-61 drill rig (B-4}. All borings were advanced with hollow stem auger, and samples were taken at 2-1/2 to 5-foot depth intervals in conjunction with performing Standard Penetration Tests (SPT). After completion, B-2, B-3 and B-4 were backfilled with bentonite. At B-1, a 1-inch diameter standpipe groundwater observation well was installed, and a protective surface monument was placed. B-1 was located at the northeast corner of the housing area. It was about 48 feet deep; and was intended to explore soil and groundwater conditions for the full depth of the slope. The standpipe groundwater observation well was installed in it to allow long term monitoring of groundwater levels. B-2 was located at the southeast corner of the housing area, was about 18 feet deep, and was intended to check for consistent THE RILEY GROUP, INC. i Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 9 of 45 conditions across the slope. B-3 and B-4 were drilled to about 50 feet deep in the commercial development lower level area in locations where fill extended deeper than the bottom of the test pits. Soil Conditions - Central Slope/Housin..�roject On the central slope, soil conditions were explored with 2 borings (B-1 and B-2) and 5 test pits (TP-1 through TP-5). B-1 was 48 feet deep and encountered mostly silty sand with some gravel that was very dense at and below depth 3 feet. There was a thin layer of sand and sandy gravel from depth 7 to 12 feet that was also very dense. At 41 feet, we encountered sandy silt with some gravel that was very dense and continued to the termination depth of 48 feet. B-2 was 18 feet deep, and had conditions similar to those at B-1. Most of the soil was silty sand with some gravel that was very dense at and below 3 feet. TP-1 through TP-4 were similar to the borings, and typically had silty sand that was very dense by depth 6 feet, and medium dense above that. At TP-5, the soil was medium dense sand with some silt to its full depth of 13 feet. Groundwater Conditions - Central Slope/Housini�Project Only 1 sample (in B-1 at 43 feet) was noted to be wet in the test pits and borings. A standpipe groundwater observation well was installed in it to allow long term monitoring of groundwater levels. The following measurements of depth to groundwater have been made to date. Table 1. Groundwater Levels - Central Slope/Housing Project Depth to Groundwater(feet) Date Boring B-1 installed 17 APRIL 2003 17APR2003 38.2 installed 17 April; not yet stabilized 30MAY2003 dry dry at 45.8 feet THE RILEY GROUP, INC. Geotechnical Engineering Report June 2, 2003 ', Proposed Rainier Ave.Miaed Use Project Project No. 2002-062B ' Renton,Washington Page 10 of 45 Soil Conditions - Commercial Development In the commercial development area, soil conditions were explored with 2 borings (B-3 and B-4) and 7 test pits (TP-6 through TP-12). We also considered 2 monitoring wells (MW-1 and MW-2)that were installed by Riley on March 19, 2001. TP-7, TP-10, TP-11, and TP-12 were located at the base of slopes (north and central), : and encountered dense/hard sandy silt or dense silty sand by depth 2 feet. At TP-6 (excavated in conjunction with removing a hydraulic hoist), silty sand fill was noted. From 0 to 4 feet, the fill contained occasional wood debris, and was medium dense. From 4 to 14 feet deep no wood was noted, and the fill was medium dense to dense. '� � We suspect the fill was associated with the�hoist. �� In TP-8 and TP-9, fill was encountered to beyond the termination depths of 12 and 13 I feet. In TP-9, the fill contained wood and auto debris from depth 5 to 13 feet. Because � these test pits did not get through the fill, 2 borings were drilled in the general vicinity � �I of the test pits. I At B-3 near TP-9 there was loose to medium dense silt sand and sand silt fill down � )� Y Y to depth 17 feet, and an "obstruction zone" from depth 11 to 17 feet (this may have represented auto debris, as was observed in TP-9}. From 17 to 35 feet, there was medium dense silty sand with wood fragments and peat pockets, and 6-inch thick layers of peat were noted at depth 23 and 28 feet. Medium dense silty sand was encountered � at about 35 feet deep, and from 41 to 49 feet there was very dense silty sand. � In B-4 (near TP-8}, there was silty sand fill down to depth 15 feet that was dense down ', to about 10 feet and then was medium dense. From 15 to 26 feet, there was medium �, dense sandy silt and silty sand. Between depth 26 and 37 feet we encountered mostly I�� i THE RILEY GROUP, INC. I il Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 11 of 45 peat with some layers of silt. There was medium dense to dense sandy silt from 37 to 45 feet, and from 45 to 54 feet there was very dense silty sand. Monitoring well MW-1 was located northeast of building 2. It encountered layers of silty sand and silty clay that ranged from about 5 to 10 feet thick. Although nothing material noted on the log definitely indicated fill (for example, man-made debris), the decreasing density/stiffness from about 15 to 25 feet may indicate fill. The soil was then dense from 25 feet to the termination depth of 35 feet: Monitoring well MW-2 was located on the north side of building 3. There was medium dense gravelly silty sand down to depth 10 feet. Below that, it encountered layers of gravelly silty sand, silt, and sand, all of which were very dense. As with MW-1, nothing material noted on the log definitely indicated fill versus native soil. However, ' based on the consistent high density from 10 feet to the termination depth of 30 feet, we I suspect this was native soil. ! i i n - mm r ial Dev 1 m nt I� Groundwater Cond t o s Co e c e op e ,I In the test pits in the commercial development area, there was moderate seepage in I TP-6 at depth 4 feet, and minor seepage in TP-7 at depth 6 feet. We interpret this to be I, perched water. It is common for near-surface water to percolate through the upper, more permeable soil, and stop on the underlying, less permeable soil. This is referred to as "perched water". Volumes of perched water typically are greatest during the wet winter months, and they decrease (or disappear) during the drier parts of the year. No seepage was noted in TP-8 through TP-12. Water levels were measured in the current borings after each boring was completed and before the auger was pulled from the hole. At the end of drilling, the depth to water in B-3 was measured at about 17 feet, and the depth to water in B-4 was measured at about 31 feet. Because the water level was measured at the end of drilling, and did not have THE RILEY GROUP, INC. � Gcotechnical Engineering Report June 2, 2003 Proposed Rainier Ave. Mixed Use Project Project No. 2002-062B Renton,Washington Page 12 of 4� time to stabilize (as it would in a standpipe groundwater obsen�ation well), it probably did not represent the static water level. At MW-1 and NIW-2, standpipe groundwater observation wells were installed to allow long term monitoring of groundwater levels. The measured levels should represent stabilized, static groundwater levels. Recent dates and depths to water are presented below. Table 2. Groundwater Levels - Commercial Development Depth to Groundwater(feet) Date Boring MW-1 Boring MW-2 both installed 19 MARCH 2O01 19MAR2001 27 23 at time of drilling; not yet stabilized 03APR2003 17.3 21.3 ' More detailed descri tions of the subsurface conditions encountered are resented on P P the Boring and Test Pit Logs, Figures A-2 through A-20. A description of terms used for soil classification is presented on Figure A-l. Laboratorv Testing Laboratory testing included determination of natural moisture content and grain size analyses. Moisture contents are presented on the boring and test pit logs adjacent to sample notation, and the results of grain size analyses are presented on Figures A-21 through A-24. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2, 2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 13 of 4S SEISNIIC CONSIDERATIONS Whole Site The site is located within Zone 3 of the Seismic Zone Map shown as Figure 16-2 of the 1997 Uniform Building Code (UBC}. This corresponds to a Seismic Zone Factor, Z, of 0.30. This, in turn, corresponds to an effective peak horizontal ground acceleration of 0.3g. We assumed the design seismic event was a Magnitude 7-1/2 earthquake with a peak horizontal ground acceleration of 0.3g. Central Slope/Housing Project It is our opinion that site conditions for the Central Slope/ Housing Project best fit the UBC description for Soil Profile Type S�, "Very Dense Soil and Soft Rock". Liquefaction is typically associated with loose, saturated fine to medium sand. Considering that the silty sand on the central slope is very dense, it is our opinion that there is not the potential for liquefaction. Commercial Development It is our opinion that site conditions for the Commercial Development best fit the UBC description for Soil Profile Type SD, "Stiff Soil Profile". Based on average soil density in the 4 borings considered, the potential for liquefaction is low. However, local areas of looser, saturated soil could liquefy. Considering the conditions observed in the borings (soil type, density, silt content; water table), it is our opinion that if there were liquefaction, it would be localized, of limited vertical and areal extent, and discontinuous. As a result, its effect would not be significant. Accordingly, the potential for liquefaction-induced settlement is also considered not to be significant. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 14 of 45 HISTORICAL SLIDE ACTIVITY IN THE SITE VICINTI'Y North Slo�e There is a history of slide activity in the project site vicinity. Numerous slides have occurred on the east-facing portion of the north slope, typically in the area starting at the right-of-way for NW 7th Street and extending to the north to as far as S 117th Place. These are described in the referenced GeoEngineers reports. A slide in April 1991, located along the eastward extension of NW 7th Street, sent slide debris onto Rainier Ave. and severed a sewer line. The line was reconstructed, but was damaged again in February 1996 by another slide. This slide activity was limited to the east-facing portion of the north slope, and located about 200 feet north of the project site. On the south-facing portion of the north slope, some sliding reportedly occurred in the late 1980's. This was located south of Taylor Ave, and was attributed to a road cut across the toe of the slope. �I Central Slone Our historical information for the central slope is based on review of aerial photos discussed in the Riley letter of June 8, 2001 (reference 6). There were no obvious _ features indicating a major landslide in the past. The central slope also is not shown on the Renton Slide Sensitive Areas map as "Very High Landslide Hazards", indicating it historically did not have l:nown mappable landslide deposits. South Slo�pe The south slope also did not have obvious features indicating a major landslide in the past, and it was not shown on the Renton Slide Sensitive Areas map as "Very High Landsiide Hazards". THE RILEY GROUP, INC. Geotechnical Engineering Report June 2, 2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 15 of 45 PREVIOUS GEOTECHNICAL ANALYSES DONE FOR THIS VICIl\TITY BY THE CITY OF RENTON The GeoEngineers work for the City of Renton concluded that soil conditions in the slide area that damaged the sewer consisted of silty sand over silt. Water would perch on the silt and saturate the silty sand. When there had been a large enough volume of water, the silty sand became unstable, and there were slides. GeoEngineers completed slope stability analyses for a slope section along the sewer line, as well as for slope sections south of the sewer line. Their analyses indicated the sewer line section would indeed become unstable when saturated, and their ' recommended slope repair included drainage measures (in combination with removal and replacement of slope debris). They also concluded that the sections south of the sewer line were stable, even when saturated. Further, they had the opinion that the slope south of the sewer slide area would likely remain stable, provided it was not destabilized by activities such as removal of vegetation, excavation, filling, or concentration of runoff. EVALUATION OF STABILITY OF NORTH, CENTRAL, & SOUTH SLOPES North Slope Based on the work by GeoEngineers, the south-facing portion of the north slope should remain stable, provided it was not destabilized by activities such removal of vegetation, excavation, filling, or concentration of runoff. Also, it was Riley's conclusion (reference 6), based on observation of apparent creep, that potential landslide activities would likely be limited to surficial failures. It is our conclusion that the south-facing portion of the north slope should remain stable with regard to deep failures, provided it was not destabilized by construction activities associated with the proposed development. THE RILEY GROUP, INCo Geotechnical Engineering Report ' June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 16 of 45 Central Slove Based on our borings, it appears that the central slope is comprised of very dense granular soil (silty sand or non-plastic sandy silt, but not clay or clayey silt) to its full depth of 50 feet. The soil and perched groundwater conditions that are linked to the slides along the sewer on the north slope are not present in the central slope. Also, there are not surficial indications of large-scale landslides. We conclude that the central slope is stable with regard to large-scale instability, in its current configuration. Over time, weathering of near-surface soil could result in shallow, surficial ravelling of soil. This is supported by the cunent geometry of the east-facing portion of the central slope. It appears that it was the result of grading by man in about 1956 [Ref. 7], and with the exception of subsequent modifications (access road, utility installation), it has maintained what was likely the original cut slope inclination. This represents a period of about 50 years, which is a normal design life for the proposed structures. South Slope The south slope historically is not considered to have a significant potential for a major i landslide. Even if it did, it is far enough away from our subject site that it does not need I to be considered, with regard to setbacks. We conclude that the south slope will not j have an impact on either the commercial development or the housing project, and that neither of these will have an impact on the south slope. DISCUSSION AND RECOMMENDATIONS The proposed mixed-use project will include commercial development and private housing. These are considered to be 2 separate projects. Considering that the soil conditions and geotechnical concerns for each project are different, recommendations are presented separately for each project. This is intended to avoid intermingling recommendations for the separate projects in order to reduce confusion regarding which THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 17 of 45 recommendations apply to which project. However, it will also result in some repetition. �I ' General - Central Slone/Housin�Project Based on our study, it is our opinion that the site is suitable for the proposed housing project construction from a geotechnical standpoint. The buildings can be supported on conventional shallow spread footings bearing on medium dense to dense native soil. Setbacks from top of slope are recommended to reduce the impact of the structures on slope stability. Careful collection and disposal of surface water are necessary so this water does not flow over the face of the steep slopes or infiltrate into the core of the slope. Potential Impacts of Project - Central Slope/Aousing Proiect Potential impacts of the proposed project include those stemming from grading, surcharges from structures, and drainage. Cutting at the top of the slope would reduce the soil surcharge on the slope, and increase stability. Filling at the top of the slope, on the other hand, would increase the soil surcharge on the slope, and reduce stability. Filling on the face of the slope could reduce stability. The surcharge of structures near the top of slope could reduce slope stability. If the project resulted in additional water infiltrating the slope or flowing over the top of the slope, this could decrease stability. Measures to decrease the potential reductions in slope stability include limiting fill on the face or top of slope, providing setbacks from top of slope for structure foundations, and providing proper drainage. Setbacks from Top of Slone- Central Slope/Housin� Proiect We recommend that structure foundations for the housing project be set back at least 15 feet from the top of the steep slopes. This can be done by placing a normal depth footing about 15 feet back from the top of the slope. It can also be done by placing the THE RILEY GROUP, INC. Geotechnical Engineering Report ` June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 18 of 45 footings deep enough so that the bottom of the footing is a horizontal distance of at least 15 feet from the face of the slope, and thus providing an "effective setback". This is often done by deepening conventional spread footings, or by using drilled piers. Site Prenaration and Grading- Central Slope/Housing Proiect Site Preparation The first step of construction should be to log and grub the site. Any utilities that are in the proposed building footprint should be relocated to outside of the building footprint, ' ; to facilitate future repair of the utility, if required. Topsoil and vegetation should be '� stripped. At our test pits, duff and topsoil typically were up to about 1/2 foot thick. i � However, TP-4 had roots and branches down to depth 2 feet. i li � The near-surface soil exposed after stripping should be silty sand. The silty sand is ; ', moisture sensitive, and will be difficult, if not impossible, to work with if it is not near I;� optimum moisture content. �� , � I �� Grading may involve cut and fi1L In areas to receive fill or to remain at existing grade, Ii � we recommend proofrolling all exposed surfaces with a heavy piece of rubber-tired � construction equipment (such as a loaded dump truck) to evaluate if any soft and i yielding areas are present. If yielding areas are observed, they should be cut to firm bearing soil and filled to grade with structural fill. After cut areas are brought to final grade, they also should be proofrolled and repaired. As discussed above, the excavated silty sand is moisture sensitive, and will be difficult, if not impossible, to work in wet weather and/or if it is not near optimum moisture content. Fill Material It may be feasible to use the silty sand from excavation as fill in dr}�weather, if it is free of organics and debris, and properly moisture conditioned. If the site grading occurs in THE RId�EY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 19 of 45 the wet season or if additional structural fill material is required, we recommend importing material that meets the following grading requirements. Table 3. U.S. Standard Sieve Size Percent Passing 3 inches 100 percent No. 4 sieve 0 - 75 percent No. 200 sieve 0 - 5 percent * *Based on the minus 3/4-inch fraction. Prior to use, Riley should examine and test all materials imported to the site for use as structural fill. A geotechnical engineer shpuld be on site to monitor the site grading and verify soil compaction. Structural Fill Placement For the purpose of this report, structural fill is defined as fill that will support buildings, slabs-on-grade, pavement, and other settlement sensitive elements. Structural fill should be placed in uniform loose layers not more than 12 inches thick and compacted to at least 95 percent of the maximum dry density. Maximum dry density, in this report, refers to that density as determined by the ASTM D 1557 compaction test procedure (Modified Proctor). The moisture content of the soil at the time of compaction should be within about 2 percent of its optimum. � Temporary Cut Slopes We expect that unsupported temporary cut slopes will be used for basements and utility trenches, and we expect that the cuts will be made mostly in dense silty sand. For these soil conditions, we recommend temporary cut slopes up to 10 feet tall that are not subjected to seepage forces be no steeper than 1 horizontal to 1 vertical (1H:1V). If , TxE RiLEY GROUP, INC. i� tGeotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 20 of 45 there were seepage, such as due to perched water, slopes at this inclination should be expected to be unstable. They might need to be made less steep. Permanent Cut and Fill Slopes If permanent cut or fill slopes are incorporated into design, they should not be steeper than 2H:1 V. Foundation Support- Central Slope/Housing Proiect We expect that soil at footing bearing elevation will consist of inedium dense to dense silty sand. If undisturbed, this soil will be suitable to provide moderate to high design bearing pressures for conventional shallow spread footings. If the footing bearing surface is disturbed, it should be overexcavated to expose competent medium dense to dense native soil, and replaced with compacted, well- graded, granular, structural fill. The term "granular" refers to soil that is predominantly sand and/or gravel, and that is not predominantly silt or clay. The exposed subgrade should be cleaned of loose or soft soil before placing the structural fill. If it is not feasible to place and compact structural fill of the type described above (such as if there is water in the footing excavation), rock spalls or crushed rock could be used instead. Perimeter footings should bear at least 1.5 feet below final exterior grade for frost protection. Interior footings should bear at least 1 foot below the floor slab. We recommend footing widths of at least 18 and 24 inches for continuous strip footings and isolated column footings, respectively. As discussed previously, the footings should be set back at least 15 feet horizontally from the top of the steep slope. This can be done by placing a normal depth footing about 15 feet back from the top of the slope. Alternatively, an "effective setback" can be achieved by deepening the footing so that its bottom is 15 feet horizontally from the THE RILEY GROUP, INC. Geotechnical Engineering Report June 2, 2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 21 of 45 face of the slope at the same elevation. This can be done by conventional spread footings in trenches, or with drilled piers. We recommend that a geotechnical engineer be present on site to inspect the foundation subgrade preparation before pouring concrete. The foundation subgrade should be undisturbed and medium dense to dense. If loose or disturbed soil is observed, it should be removed and replaced with structural fill or crushed rock. If prepared footing subgrades are to remain exposed during the winter season or periods of wet weather, it is recommended that they be covered with a lean concrete "mud mat" to help protect the subgrades after they have been inspected and until the footings are poured. For footings constructed as recommended, and bearing on undisturbed, competent , (medium dense to dense) native soil, we recommend a design allowable bearing ', pressure of not more than 3000 pounds per square foot (psfl. For short-term loads, such I as wind and seismic, a 1/3 increase in this allowable bearing pressure can be used, as I�� long as this conforms with the appropriate current UBC loading combinations. With the expected structural loading and the recommended foundation bearing pressure, total settlement of footings should not be more than 1 inch, and differential settlement between adjacent footings or across a distance of about 20 feet should not be more than 1/2 inch. We expect that most of the settlement will occur by the end of construction. Lateral forces may be resisted by friction at the base of foundations and by passive soil resistance acting against the buried portion of foundations. To compute passive resistance, we recommend using an equivalent fluid density of 2Q0 pounds per cubic foot (pc�}. This value is based on the foundations being constructed neat against undisturbed competent soil or backfilled with structural fill, and assumes that the ground surface on the resisting side is level for a distance of at least 3 times the depth of the foundation. The upper 1 foot of soil should not be included in the passive resistance �THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Miaed Use Project Project No. 2002-062B Renton, Washington Page 22 of 45 calculation because it can become disturbed by erosion or future grading activity. For base friction, a factor of 0.4 may be used between concrete and soil. The coefficient of ' friction should be applied to the vertical dead load only. These values include a safety factor of about 1.5 and 2 applied to the estimated ultimate values for frictional and passive resistance, respectively. ' We recommend that footing drains be installed on the outside of perimeter footings. The footing drains should consist of 4-inch-minimum diameter, perforated or slotted, smooth wall, rigid, PVC pipe, laid at the bottom of the footing. The drain line should be sunounded with free draining pea gravel or washed rock that is wrapped in filter fabric. The top 1 foot of backfill should consist of relatively impermeable material to limit surface water infiltration into the perimeter drain. A typical footing drain detail is shown on Figure 4. The footing drains and roof downspouts should be tightlined separately to an approved discharge facility. Slabs-on-Grade- Central Slone/Housing Proiect �' Subgrades for slabs-on-grade should be proofrolled and repaired as necessary, as ', described in the Site Pre aration and Gradin section of this re ort. If the on site soil I P g P , can not be compacted to provide a dense and unyielding surface, it should be replaced I'I with 1 foot of compacted structural fill. Immediately below the floor slab, we recommend placing a 6-inch thick capillary break layer consisting of clean, free- draining gravel or sand and gravel that has less than 5 percent fines (material passing a U.S. No. 200 sieve). This material will reduce the potential for upward capillary movement of water from the underlying soil and subsequent wetting of the floor slab. A suitable vapor barrier should be placed on top of the capillary break. The vapor banier may be covered with 2 inches of clean, moist sand to guard against damage to - the vapor barrier during construction and to aid in curing of the concrete. THE RILEY GROliP, INC. l___, Geotectuucal Engineering Report June 2,2003 Proposed Rainier Ave.Miaed Use Project Project No. 2002-062B Renton,Washington Page 23 of 45 Subsurface Walls - Central Slope/Housin� Proiect � Basement walls should be waterproofed and fully drained. Wall drains should be i similar to those recommended for perimeter footing drains. There should be a zone of �! free draining material at least 1 foot wide next to the wall. The top 1 foot of backfill I! should consist of relatively impermeable material to limit surface water infiltration into ' the wall drain. The perforated pipe should drain to daylight. A typical retaining wall drainage detail is shown on Figure 5. As an alternative to a layer of gravel, a pre- fabricated drainage panel, such as Miradrain, could be used. The lateral pressure acting on the wall is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement which can occur as backfill is placed, wall drainage conditions, and the inclination of the backfill. Subsurface walls should be provided with wall drains, as described above. For walls that are free to yield at the top at least 0.001 times the height of the wall (active condition), soil pressures will be less than if movement is limited by such factors as wall stiffness or bracing (at- rest condition). We recommend that walls supporting horizontal backfill and not subjected to hydrostatic forces be designed using a triangular earth pressure distribution equivalent to that exerted by a fluid with a density of 35 pcf for yielding (active condition)walls, and 55 pcf for non-yielding {at-rest condition) walls. These recommended lateral earth pressures are based on the assumption of a horizontal - - round surface adjacent to the wall for a distance of at least the subsurface height of the g wall, and do not account for surcharges. Additional lateral earth pressures should be considered for surcharge loads acting adjacent to subsurface walls and within a distance , equal to the subsurface height of the wall. This would include the effects of surcharges such as tr�c loads, floor slab loads, or other surface loads. Increased lateral earth ' pressure due to adjacent areal vertical surcharge pressures (such as uniform floor slab ', loads) can be taken as a uniform pressure equal to 0.3 times the vertical surcharge �', pressure for active conditions, and 0.5 times the vertical surcharge pressure for at-rest !I I THE RILEY GROUP, INC. I!' Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 24 of 45 conditions. Traffic surcharges are often accounted for by assuming a surcharge equivalent to 2 feet of soil, which corresponds to about 250 psf vertical pressure. Lateral forces on subsurface retaining walls can be resisted by friction and passive resistance, as described for footings, as well as by structural elements of the building. RetaininE Structures- Central Slope/Housing Proiect Current plans call for building some retaining structures and placing some fill in the gully along the utility easement on the east-facing portion of the central slope. Considering that this filling would tend to reestablish the slope grade that existed before the gully was dug, it should not have a negative impact on the stability of adjacent slopes. We expect the structures would not be more than 10 feet tall. They could be conventional concrete retaining walls, mechanically stabilized earth walls (such as Keystone walls or similar), or ecology block walls. The subgrade for the walls should be excavated to provide a level base for the wall. Utilities in the gully should be located and potholed first so they do not get damaged. The subgrade should be medium dense to dense. If not, it should be repaired. Backfill behind the wall should be compacted to at least 95 percent of the maximum dry density. For a manufacturer's design,the following soil parameters can be used. • 120 pcf dry density •35 degrees internal friction angle •2000 psf design allowable bearing pressure •0.4 frictional lateral resistance factor(includes safety factor of about 1.5) •35 pcf equivalent fluid for active pressure •200 pcf equivalent fluid for passive resistance {includes safety factor of about 2) THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 II Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B '� Renton,Washington Page 25 of 45 Drainage - Central Slope/Housin�Proiect Construction We expect that water encountered during construction could come from shallow perched water, depending on the time of year. If minor water seepage is encountered or if rainfall collects in excavations during construction, we recommend that the contractor slope the bottom of excavations and collect the water into ditches and sump pits from which the water can be pumped and discharged into a storm drain. Surface Final exterior grades should promote free and positive drainage away from the building. Water should not pond or collect adjacent to the immediate building area. We recommend providing a drainage gradient of at least 3 percent for a distance of at least 10 feet from the building perimeter. All runoff water from paved areas, roofs, and other impervious surfaces should be collected and discharged to the storm drain system. If there are yards between the house and the slope, yard drains should be installed to collect water and discharge it to the storm drain system. Water should not be allowed to flow over the slope, or to pond in yards and infiltrate into the ground. Subsurface We recommend that wall drains be installed for all subsurface walls. This is discussed in the Subsurface Walls section of this report. We also recommend that perimeter ; footing drains be installed. This is discussed in the Foundation Support section of this �� report. Footing drains and roof downspouts should be tightlined separately to the storm �� drain. 'THE RILE�'GROUP, I?�C. Geotechnical Engineering Report June 2, 2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 26 of 45 Utilities - Central Slope/Housing Proiect We expect that any new utilities will be relatively shallow (say 5 feet deep or less). The soil within this depth can be excavated with a backhoe. Significant groundwater is not expected within this depth. Utility pipes should be bedded and backfilled in accordance with American Public Works Association (APWA) specifications. If local codes supercede APWA specifications, bedding and backfill should be completed in accordance with those codes. As a minimum, trench backfill should be placed and compacted as structural fill, as described in the Site Preparation and Grading section of this report. Where utilities are located below unimproved areas where some settlement of trench backfill is acceptable, the degree of compaction can be reduced to at least 90 percent of the maximum dry density as determined by the referenced ASTM D-1557 standard. Pavement - Central Slape/Housing Proiect Pavement subgrades should be proofrolled and repaired as necessary, as described in the Site Preparation and Grading section of this report. Regardless of the relative compaction achieved, the subgrade should be firm and unyielding before paving. As recommended for slab-on-grade subgrades, if the on site soil can not be compacted to provide a dense and unyielding surface, it should be replaced with 1 foot of compacted structural fill. The final subgrade should be proofrolled before paving. � � I For residential passenger vehicle driveway and parking areas, we recommend a pavement section consisting of 2 inches of asphalt concrete over 4 inches of crushed rock base. As an alternative, the 4 inches of crushed rock base could be replaced with 3 inches of asphalt treated base. T�-IE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No.2002-062B Renton,Washington Page 27 of45 General- Commercial Development Based on our study, it is our opinion that the site is suitable for the proposed commercial development construction from a geotechnical standpoint. It appears that Buildings 2 and 3 can be supported on conventional shallow spread footings bearing on medium dense to dense or hard native soil. Building 1 and the parking structure are at least partially underlain by up to 40 feet of soil that is not suitable to provide shallow foundation support, and will therefore require pile support where unsuitable soil is not removed. We recommend against the proposed cut into the toe of the north slope for Building 1 and the parking structure. The proposed cut into the toe of the central slope for Buildings 2 and 3 is considered feasible from a geotechnical standpoint. However, it will require a shoring system. � i Potential Imnact of Proiect-Commercial Development Potential impacts of the proposed commercial development are associated primarily _ with the proposed cutting into the toe of slopes. The north and central slopes appear to be stable in their current condition with regard to deep-seated soil movement. However, due to their steepness, they are prone to surficial creep and surficial ravelling over time. To cut into the toe of these slopes without providing support would reduce their stability. Also, other modifications to these slopes (such as excavation, filling, increased levels of water, or removal of vegetation) could reduce their stability. Measures to maintain slope stability and protect the structures include providing support to the toe of slope and providing a structure setback from the toe. For the central slope, it is our opinion that for limited heights of cut (up to about 10 feet), cantilever soldier pile shoring will provide adequate support to the slope, and allow the buildings to be set into the slope. For the north slope, it is our opinion that it is best not to cut into the toe of slope, but instead to provide a structure setback. Any work"incidental" to the proj ect (for example, landscaping) should not remove vegetation from steep slopes, or alter (increase) water on the slopes. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 , Proposed Rainier Ave.Mixed Use Project Project No.2002-062B Renton,Washington Page 28 of45 Setbacks from Toe of Slope-Commercial Development For the central slope, we recommend a building setback of 10 feet from the toe of slope. ' As an alternative, the slope could be shored, and Buildings 2 and 3 could be set into the slope. For the north slope, we recommend against cutting into the toe of the slope for Building 1 and the parking structure, and instead recommend a building setback 25 feet from the toe of slope. Altematively, if a debris wall were constructed at the t�e of slope, the setback could be reduced to 10 feet. Excavation - Commercial Development The proposed construction will have 2 potenrial areas of excavation. Excavation may take place at the toe of the central slope. This would require shoring. Excavation in the level area of the site will be required for the parking structure for its below grade level. This would probably be done with laid back,unsupported,open cuts. Temporary Cut Slopes The existing steep north and central slopes typically are at about 1-1/2H:1V inclination. It is advisable not to cut thein any steeper, even on a temporary basis. Accordingly, temporary cut slopes do not apply to the north and central slopes. We expect that unsupported temporary cut slopes will be used mostly far the ercavation for the parking structure. It is our understanding that the excavation will be relatively shallow, and we assume it will not exceed 10 feet. We expect soil conditions in the depth of excavation to range from uncontrolled, loose silty sand fill with debris; to dense or hard sandy silt. For these soil conditions, we recommend temporary cut slopes up to 10 feet tall that are not subjected to seepage forces be no steeper than 1-1/2H:1V. If there were seepage, such as due to perched«�ater, slopes at this inclination should be THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 _ Proposed Rainier Ave.Mixed Use Project Project No.2002-062B Renton,Washington Page 29 of 45 expected to be unstable. They could require some support, or might need to be made less steep. il ' Shorin� If it is decided to cut into the toe of the central slope, we recommend that it be shored. We expect cut heights will not be more than about 10 feet. Cantilever soldier piles and lagging seems appropriate for these heights. The shoring will be against steep backslopes (typically about 1-1/2H:1�, and lateral earth pressures will be high. Our recommended earth pressures, parameters, and assumptions for design of a cantilever soldier pile wall with a 1-1/2H:1V backslope are presented on Figure 6. The pressures are presented in terms of equivalent fluid density; i.e., a triangular earth pressure distribution equivalent to that which would be exerted by a fluid with the density noted. The following assumptions and recommendations apply to the figure. • The water table was assumed to be at the base of the excavation, on both sides of the soldier pile wall. • Active pressure above the base of the excavation acts on the full center-to- center pile spacing. • Below the base of the excavation, active pressure acis on 1 pile diameter, and passive resistance acts on 2 pile diaineters. � Any nearby surcharges (within a horizontal distance equal to the height of the wall) should be considered on an individual basis. Lagging can be designed for pressures equal to 50 percent of those shown for design of piles, due to arching effects. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No.2002-062B Renton,Washington Page 30 of 45 A monitoring program should be implemented to verify the performance of the shoring system. The first step in this program should consist of setting reference points for horizontal and vertical control, and setting monitoring points on the piles after they are installed and before any excavation is done. The documentation should include a photographic record. Monitoring of the shoring system should be done daily as the excavation proceeds, and then weekly once the excavation is completed. A registered land surveyor should be retained to establish the baseline data, and to complete a survey every 2 weeks to check the contractor's readings. Daily monitoring can be done by the contractor. Monitoring should continue until the permanent building walls are adequately braced. Monitoring should include surveying the vertical and horizontal alignment of the top of each soldier pile. Monitoring points should also be established at the middle height of the shoring at 25-foot horizontal intervals. These mid-level points should also be surveyed to record horizontal and vertical movements. The project's structural and geotechnical engineers '� should review the monitoring data weekly, and at any time there is unexpected jmovement. '� Site Preparation and Gradin�- Commercial Development Site Pre aration I P The first step of construction should be to demolish existing structures. Any utilities , that are in the proposed building footprints should be relocated to outside of the I building footprint. Pavement should be stripped. I From a geotechnical standpoint, the concrete rubble and/or stripped asphalt could be used as fill if it were placed at the bottom of deeper fills in pavement (non building) areas, and at least 2 feet below final grade. If the rubble is to be used as fill, it should be broken up into pieces no larger than 6 inches, laid flat, and not"nested", and rnixed with soil to avoid creating voids. Concrete debris that is placed as recoirunended should THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No.2002-062B Renton,Washington Page 31 of 45 perform adequately as structural fill; however, it could result in obstructions that would complicate trenching for utility installation. The near-surface soil exposed after stripping is expected to be silty sand or sandy silt. The silty sand is moisture sensitive, and will be difficult, if not impossible,to work with if it is not near optimum moisture content. The sandy silt is even more moisture sensitive, and generally is not suitable for reuse as fill. We suspect grading may involve cut and fill, but we expect it will be of limited height. Prior to placing fill,we recommend proofrolling all exposed surfaces with a heavy piece of rubber-tired construction equipment (such as a loaded dump truck) to evaluate if any soft and yielding areas are present. If yielding areas are observed, they should be cut to firm bearing soil and filled to grade with structural fill. After cut areas are brought to final grade, they also should be proofrolled and repaired. As discussed above, the silty sand is moisture sensitive, and will be di�cult, if not impossible, to work in wet weather and/or if it is not near optimum moisture content. Fill Material It may be feasible to use the silty sand from excavation as fill in dry weather, if it is free '� of organics and debris, and properly moisture conditioned. If it is decided not to reuse it, and structural fill material is required, we recominend importing material that meets the following gradation requirements. Table 4. U.S. Standard Sieve Size Percent Passing , 3 inches 100 percent , No. 4 sie��e 0 - 75 percent ' No. 200 sieve 0 - 5 percent * iI *Based on the minus 3i4-inch fraction. THE RILEY GROUP, INC. i Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No.2002-062B Renton,Washington Page 32 of 45 ' Prior to use, Riley should examine and test all materials imported to the site for use as structural fill. A geotechnical engineer should be on site to monitor the site gra.ding and verify soil compaction. Structural Fill Placement For the purpose of this report, structural fill is defined as fill that will support buildings, slabs-on-grade, pavement, and other settlement sensitive elements. Structural fill should be placed in uniform loose layers not more than 12 inches thick and compacted to at least 95 percent of the maximum dry density. Maximum dry density, in this report, refers to that density as deternlined by the ASTM D 1557 compaction test procedure (Modified Proctor). The moisture content of the soil at the time of compaction should , be within about 2 percent of its optimum. ' Permanent Cut and Fill Slopes �Ii If permanent cut or fill slopes are incorporated into design, they should not be steeper 'I than 2H:1 V. Foundation Support-Commercial Development Based on our exploration, it appears that Buildings 2 and 3 can be supported on conventional shallow spread footings bearing on medium dense to dense or hard native soil. Building 1 and the parking structure are at least partially underlain by up to 40 feet of fill and organic soil that is not suitable to provided shallow foundation support. They will require pile support in the areas of deep unsuitable soil. In other parts of the buildings, competent soil is at shallow depth. If the depth to competent native soil decreases enough across the building footprint, it would be acceptable to switch back to spread footings. A depth of 5 to 10 feet (to suitable bearing soil) is commonly considered the depth at which one switches from shallow foundations to deep foundarions. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 33 of 45 Shallow Spread Footin�s Based on the available soil information in the vicinity of Buildings 3 and 2, it appears that there is suitable bearing soil (medium dense to dense silty sand or sandy silt) within a depth of about 5 feet below existing grade. Accordingly, it appears that shallow spread footings are appropriate for Buildings 3 and 2. Footings should bear on undisturbed, medium dense to dense native silty sand or sandy silt. If the planned footing bearing surface is disturbed or consists of fill, it should be overexcavated to expose competent medium dense to dense native soil, and replaced with compacted, well-graded, granular, structural fill. The term "granular" refers to soil that is predominantly sand and/or gravel, and that is not predominantly silt or clay. The exposed subgrade should be cleaned of loose or soft soil before placing the structural fill. If it is not feasible to place and compact structural fill of the type described above (such as if there is water in the footing excavation from seepage or rain), rock spalls or crushed rock could be used instead. Perimeter footings should bear at least 1.5 feet below final exterior grade for frost protection. Interior footings should bear at least 1 foot below the floor slab. We recommend footing widths of at least 18 and 24 inches for continuous strip footings and isolated column footings, respectively. We recommend that a geotechnical engineer be present on site to inspect the foundation subgrade preparation before pouring concrete. The foundation subgrade should be undisturbed and medium dense to dense. If loose or disturbed soil is observed, it should be removed and replaced with structural fill or crushed rock. If prepared footing subgrades are to remain exposed during the winter season or periods of wet weather, it is recommended that they be covered with a lean concrete "mud mat" to help protect the subgrades after they have been inspected and until the footings are poured. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 34 of 45 For footings constructed as recommended, and bearing on undisturbed, competent (medium dense to dense) native soil, we recommend a design allowable bearing pressure of not more than 3000 pounds per square foot (ps�. For short-term loads, such as wind and seismic, a 1/3 increase in this allowable bearing pressure can be used, as long as this conforms with the appropriate cunent UBC loading combinations. With the expected structural loading and the recommended foundation bearing pressure, total settlement of footings should not be more than 1 inch, and differential settlement between adjacent footings or across a distance of about 20 feet should not be more than 1/2 inch. w'e expect that most of the settlement will occur by the end of construction. Lateral forces may be resisted by friction at the base of foundations and by passive soil resistance acting against the buried portion of foundations. To compute passive resistance, we recommend using an equivalent fluid density of 200 pounds per cubic foot (pc�. This value is based on the foundations being constructed neat against undisturbed competent soil or backfilled with structural fill, and assumes that the ground surface on the resisting side is level for a distance of at least 3 times the depth of the foundation. The upper 1 foot of soil should not be included in the passive resistance calculation because it can become disturbed by erosion or future grading activity. For base friction, a factor of 0.4 may be used between concrete and soil. The coefficient of friction should be applied to the vertical dead load only. These values include a safety factor of about 1.5 and 2 applied to the estimated ultimate values for frictional and passive resistance, respectively. We recommend that footing drains be installed on the outside of perimeter footings. The footing drains should consist of 4-inch-minimum diameter, perforated or slotted, smooth wall, rigid, PVC pipe, laid at the bottom of the footing. The drain line should be surrounded with free draining pea gravel or washed rock that is wrapped in filter THE RILEY GROliP, INCo Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 35 of 45 fabric. The top 1 foot of backfill should consist of'relatively impermeable material to limit surface water infiltration into the perimeter drain. A typical footing drain detail is shown on Figure 4. The footing drains and roof downspouts should be tightlined separately to an approved discharge facility. Pile Foundations General Building 1 and the parking structure are at least partially underlain by up to about 40 feet of fill and organic soil that is not suitable to provided shallow foundation support. They will require pile support in the areas of deep unsuitable soil. If the depth to competent native soil decreases enough across the building footprint, it may be desirable to switch back to spread footings. A depth of 5 to 10 feet (to suitable bearing soil) is commonly considered the depth at which one switches from shallow foundations to deep foundations. Pile Tvpe We expect subsurface conditions include dense near-surface fill, deeper looser fill that contains obstructions (either natural or man-made), and suitable bearing soil at depths that will be highly variable. Drilled and cast-in-place piles (augercast piles} are not considered appropriate for the site subsurface conditions. These piles could be subject to loss of grout in debris (such as car parts) or oversized material, such as a pocket of cobbles and boulders. In addition, augercast pile equipment typically does not have the ability to crowd (exert downward pressure on) the auger, which could result in inadequate penetration into bearing soil. Driven piles appear to be the most appropriate type of deep foundation support. For this particular project, timber piles do not appear to be appropriate, due to their relatively THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 36 of 45 low structural capacity, and the potential for damage to the pile during hard driving. Considering the anticipated variable depths of pile penetration, precast concrete piles ' also appear inappropriate due to their poor length flexibility (difficult cutting or splicing to adjust to changing field conditions). Accordingly, we recommend steel piles, due to their good length flexibility as well as their ability to withstand hard driving. Driven steel piles could consist of pipe piles or H-piles. It is our opinion that H-piles would probably be more successful in getting through or around debris and obstructions, and also more effective at penetrating into very dense bearing material. However, once driven, they could not be inspected for damage. Pipe piles would require harder driving to get past obstructions and into very dense bearing material, but they could be checked for damage after they were driven. We assumed that pipe piles would be used, and that they would have design capacities in the range of 100 kip per pile. We recommend that pipe piles be seamless pipe (not spiral welded), with a wall thickness of at least 3/8 inch. The piles should be driven to practical refusal with an appropriately sized pile driving hammer. (Pile installation criteria are discussed in a later section of this report.) We recommend that the piles be driven closed-end and reinforced with a conical tip. The reinforcement is intended to aid in penetrating into very dense soil, as well as to advance through debris, boulders, or other obstructions that may be encountered. Piles should be placed at least 3 diameters apart (center to center)to avoid reduction in capacity due to group action. � Allowable Design CapacitX Piles should be driven through loose/soft compressible soil to refusal in the very dense silty sand unit that was encountered at about depths of 40 to 45 feet at the boring locations. The piles should be considered to act completely in end bearing. For , undamaged piles that are driven to practical refusal with properly sized equipment, we THE RILEY GROUP, INC. li Geotecluucal Engineering Report June 2, 2003 Proposed Rainier Ave. Miaed Use Project Project No. 2002-062B Renton,Waslungton Page 3'7 of 45 recommend an allowable design end bearing stress of 100 kips per square foot (ks�. For a 12-inch diameter pile, this bearing stress corresponds to an allowable axial downward (compressive) design load of 80 kips, and for a 14-inch diameter pile it corresponds to an allowable load of 110 kips. The recommended capacity is based on estimated soil characteristics only. Pile capacities based on the strength of pile materials should be determined by the structural engineer. Settlements of pile foundations that are designed and constructed as recommended are expected not to exceed about 1/2 inch under compressive loading. The majority of this should take place quickly after pile loading. The 1997 Uniform Building Code (UBC) allows a 1/3 increase in allowable soil stresses for wind and seismic loads, for certain load combinations. If the appropriate load combinations are used, the allowable axial pile capacity recommended above can be increased by 1/3 when considering wind and seismic loads. Estimated Pile Penetration De�ths Pile penetration depths will be a function of the depth to the top of the dense silty sand unit and the pile penetration into the dense soil. It is difficult to assess the depth of pile penetration, as it is dependent on the soil conditions and the driving equipment used. It is estimated that pipe piles may penetrate up to about 5 to 10 feet into the dense sand. At the exploration locations, the depth to dense sand was about 40 to 45 feet. Based on this, it is estimated that pile penetration depths could range from about 45 to 55 feet below the existing ground surface at the exploration locations. Preliminary Pile Drivina Recommendations Piles should be installed by driving continuously to virtual refusal with an appropriately sized air or diesel hammer. "Virtual refusal" is typically defined as a driving resistance on the order of 6 to 8 blows per inch. For preliminary planning purposes, we THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Miaed Use Project Project No. 2002-062B Renton,Washington Page 38 of 45 recommend that the hammer should deliver at least 30,000 foot-pounds of driving energy per blow for the recommended pile type and capacity. It is noted that diesel hammers may experience difficulty in firing when driving through the loose/soft soil deposits. Specific driving criteria required to attain the recommended allowable capacity presented above can be established only after the actual pile size and driving equipment are chosen. We recommend that once the pile size and driving equipment have been selected, that a wave equation analysis (WEAP) be completed to evaluate better the driving requirements and compatibility of the pile and hammer. For this project and pile support conditions, we recommend that a safety factor of 3 be applied to ultimate dynamic driving resistance to evaluate driving criteria for the pile design capacity. To aid in the evaluation of the proposed driving equipment, we recommend that the contractor furnish the information rec�uested to the geotechnical engineer for review at least three weeks before mobilizing pile driving equipment to the site. The results of the wave equation analysis should be checked at the start of actual pile driving operations. This will help confirm driving criteria, and provide better estimates of pile penetration. We recommend that the first piles be installed at design locations near the existing borings to act as test piles. Depending on the results of these test piles, additional test piles may be advisable. The test piles should be driven at design locations with the hammer that will be used for production driving. After being properly driven, test piles will serve as production piles. The test program should confirm driving criteria and give a better estimate of actual required pile lengths. Obstructions, in the form of boulders, debris, or possibly logs or stumps, could be encountered. This could prevent piles from penetrating to the necessary depth. If deep obstructions are encountered, it may be necessary to modify pile locations. If THE RILEY CsROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Miaed Use Project Project No. 2002-062B Renton,Wastiington Page 39 of 45 obstructions are shallow, it may be possible to dig them out and maintain the planned pile location. After driving, the pipe piles should be "lamped" to check for damage. It is also advisable to carefully monitor piles for potential heave, or for potential degradation of bearing soil due to pile driving operations. Accordingly, it is recommended that the top elevation of each pile be recorded immediately after the pile is driven, and that top of pile elevations be checked periodically to check for potential heave. In addition, after pile installation has been completed, a number of piles should be redriven to refusal to check for potential heave and/or degradation of bearing soil. Slabs-on-Grade - Commercial Development Although soil conditions at B-3 and B-4 are not considered suitable for shallow foundation support, they probably are adequate to support a lightly loaded slab-on- grade. Uncontrolled fill is unpredictable, and a slab-on-grade supported on uncontrolled fill would have a greater potential to settle than if it were supported on competent native soil. However, to avoid settlement would require supporting the slab on piles, which would be difficult to justify from a cost perspective. Subgrades for slabs-on-grade should be proofrolled and repaired as necessary, as described in the Site Preparation and Grading section of this report. If the on site soil can not be compacted to provide a dense and unyielding surface, it should be replaced with 1 foot of compacted structural fill. Immediately below the floor slab, we recommend placing a 6-inch thick capillary break Iayer consisting of clean, free- draining gravel or sand and gravel that has less than 5 percent fines (material passing a U.S. No. 200 sieve). This material will reduce the potential for upward capillary movement of water from the underlying soil and subsequent wetting of the floor slab. A suitable vapor banier should be placed on top of the capillary break. The vapor THE RILEY GROUP, I:�1C. � Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B , Renton,Washington Page 40 of 4� banier may be covered with 2 inches of clean, moist sand to guard against damage to the vapor barrier during construction and to aid in curing of the concrete. I Subsurface Walls - Commercial Development i� '�� � If building walls are cast directly against soldier pile shoring, they can be considered to be subsurface walls. Proper drainage of walls cast against shoring is important both for , the wall and the stability of the retained soil. These walls should be waterproofed and fully drained. We recommend a drainage system consisting of pre-fabricated drainage panels, such as Miradrain, that are attached to the lagging face and connected to a pipe li at the base of the wall. The pipe should then be tightlined through the footing to collector pipes that lead to a sump for discharje of collected water. A typical wall drainage detail is shown on Figure 7. If walls are constructed against the shoring, they can be designed for the same pressures that were recommended for the shoring. If basement walls are constructed, and then backfilled (such as in temporary cut slope areas for the parking structure), different design wall pressures apply. The lateral pressure acting on the wall is dependent on the nature and density of the soil behind the wall, the amount of lateral wall movement which can occur as backfill is placed, wall drainage conditions, and the inclination of the backfill. Subsurface walls should be provided with wall drains, as described above. For walls that are free to yield at the top at least 0.001 times the height of the wall (active condition), soil pressures will be less than if movement is limited by such factors as wall stiffness or bracing (at-rest condition). We recommend that walls supporting horizontal backfill and not subjected to hydrostatic forces be designed using a triangular earth pressure distribution equivalent to that exerted by a fluid with a density of 35 pcf for yielding (active condition) walls, and 55 pcf for non-yielding (at-rest condition) walls. THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 41 of 45 These recommended lateral earth pressures are based on the assumption of a horizontal ground surface adjacent to the wall for a distance of at least the subsurface height of the wall, and do not account for surcharges. Additional lateral earth pressures should be considered for surcharge loads acting adjacent to subsurface walls and within a distance equal to the subsurface height of the wall. This would include the effects of surcharges such as traffic loads, floor slab loads, or other surface loads. Increased lateral earth pressure due to adjacent areal vertical surcharge pressures (such as uniform floor slab loads) can be taken as a uniform pressure equal to 0.3 times the vertical surcharge pressure for active conditions, and 0.5 times the vertical surcharge pressure for at-rest �� conditions. Traffic surcharges are often accounted for by assuming a surcharge equivalent to 2 feet of soil, which corresponds to about 250 psf vertical pressure. Lateral forces on subsurface retaining walls can be resisted by friction and passive resistance, as described for footings, as well as by structural elements of the building. , Drainage- Commercial Development I', Construction !, We expect that water from shallow perched water could be encountered during !, construction. If it is, we expect it will be limited, and that the excavation could be dewatered with sumps and pumps. Surface Final exterior grades should promote free and positive drainage away from the building. Water should not pond or collect adjacent to the immediate building area. We recommend providing a drainage gradient of at least 3 percent for a distance of at least 10 feet from the building perimeter. T'HE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Miaed Use Project Project No. 2002-062B Renton,Washington Page 42 of 45 Subsurface We recommend that wall drains be installed for all subsurface walls. This is discussed in the Subsurface Walls section of this report. We also recommend that perimeter footing drains be installed. This is discussed in the Shallow Spread Footings section of this report. In pile-supported sections there should also be a drain by the grade beams, similar to perimeter footing drains. Footing drains and roof downspouts should be tightlined separately to the storm drain. , Utilities - Commercial Development ' We expect that any new utilities will be relatively shallow (say 5 feet deep or less). The soil within this depth can be excavated easily with a backhoe. Significant groundwater is not expected within this depth. Utility pipes should be bedded and backfilled in , accordance with American Public Works Association (APWA) specifications. If local ' codes supercede APWA specifications, bedding and backfill should be completed in ', ', � accordance with those codes. As a minimum, trench backfill should be placed and I'I � � compacted as structural fill, as described in the Site Preparation and Grading section of � � this report. � � � Where utilities are located below unimproved areas where some settlement of trench backfill is acceptable, the degree of compaction can be reduced to at least 90 percent of , the maximum dry density as determined by the referenced ASTM D-1557 standard. I . ' � '- Pavement - Commercial Develonment ; '� ;- Pavement subgrades should be proofrolled and repaired as necessary, as described in the Site Preparation and Grading section of this report. Regardless of the relative compaction achieved, the subgrade should be firm and unyielding before paving. As � - recommended for slab-on-grade subgrades, if the on site soil can not be compacted to ' provide a dense and unyielding surface, it should be replaced with 1 foot of compacted �I structural fill. The final subgrade should be proofrolled before paving. This II THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 43 of 45 preparation should provide adequate support for flexible pavement. However, in areas where fill and/or peat are left in place, there could be some settlement of the pavement surface over time. For passenger vehicle parking lot areas, we recommend a pavement section consisting of 2 inches of asphalt concrete over 5 inches of crushed rock base. For passenger vehicle parking lot entrances and traffic lanes used by heavy trucks, we recommend a pavement section consisting of 3 inches of asphalt concrete over 8 inches of crushed rock base. As an alternative, the 5 and 8 inches of crushed rock base could be replaced with 3-1/2 and 5-1/2 inches of asphalt treated base, respectively. LIMITATIONS �I This report has been prepared for JDA Group, LLC. It is intended for specific application to the proposed Rainier Ave. Mixed Use Project in Renton, Washington, �� and for the exclusive use of JDA Group, LLC and their authorized representatives. The analyses and recommendations presented in this report are based on data obtained from the explorations on site. Variations in soil conditions can occur, the nature and e�rtent of which may not become evident until construction. If variations appear evident, The Riley Group should be requested to reevaluate the recommendations in this report prior to proceeding further with construction. Within the limitations of scope, schedule, and budget for our sen�ices, we have attempted to complete our work in accordance with generally accepted professional � principles and practices in the tield of geotechnicai engineering followed in this area at the time this report was prepared. No warranty, express or implied, is made. THE RILEY GROtiP, INC. Geotechnical Engineering Report June 2,2003 , Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B �, Renton,Washington Page 44 of 45 � We appreciate the opportunity to be of service to you. If there are any questions or 'i comments concerning this report, or if we can provide additional services, please call. '' T'I�RII..EY GROUP, INC. .. � . .. �' �p;��i M, 1,J;, �.�� ti V�iA� �l 4..�4�� Q� U�� ��. r:(� � � '�` �'r � �; !�": Y��, �?, 1M9'.��'0 w�� E�s=GISTE4�'�{� ��NAL�� a� �;�P�R�s ��-C�E�??.ab4 William M. Kuck, P.E. Senior Engineer Report Distribution JDA Group, LLC Baylis Architects Attachments Figure 1 Site Vicinity Map Figure 2 Site and Exploration Plan Figure 3 Topographic Site Plan Figure 4 Typical Footing Drain Detail Figure 5 Retaining Wall Drainage Detail Figure 6 Shoring Pressure Diagram (1-1/ZH:1V Backslope) Figure 7 Typical Wall Drainage Detail Figure A-1 Unified Soil Classification System Figures A-2 to A-11 Boring Logs (B-1 through B-4) Figures A-12 to A-16 Test Pit Logs(TP-1 through TP-12) Figures A-17 to A-20 Monitoring Well Logs {MW-1 and MW-2} Figures A-21 to A-24 Grain Size Analyses THE RILEY GROUP, INC. Geotechnical Engineering Report June 2,2003 � Proposed Rainier Ave.Mixed Use Project Project No. 2002-062B Renton,Washington Page 45 of 45 r�, References: References/Information Provided bv the City of Renton 1. GeoEngineers;May 16, 1991; "Preliminary Geotechnical Evaluation, Landslide and Broken Sewer Lines, Slope West of Rainier Avenue North, Renton, Washington, for City of Renton" 2. GeoEngineers; October 4, 1991; "Report, Supplemental Geotechnical Engineering Services, Sewer Line Reconstruction and Slope Stabilization, Slope West of Rainier Avenue North, Renton, Washington, for City of Renton" 3. GeoEngineers; November 6, 1997; "Report, Geotechnical Engineering Services, Sewer Line Reconstruction, Rainier Avenue North and NW 7th Street, Renton, Washington", for City of Renton 4. Geo Consultants; May 8, 1991; "Slope Failure Study, Mr. Chester Rindfuss' Residence, 676 Taylor Avenue Northwest, Renton, Washington", for Mr. Chester Rindfuss 5. Geo Group Northwest; February 18, 1993; "Slope Stability Analysis and Landslide Stabilization Design, 676 Taylor Avenue NW, Renton, Washington", for Mr. John McFarland References/Information from Previous Work bv Rile,y 6. The Riley Group; June 8, 2001; "Preliminary Slope Stability Study, Meyer Property, 559 to 625 Rainier Avenue North, Renton, Washington"; for Mr. Jack Alhadeff 7. The Riley Group; October 29, 2002; "Slope Evaluation, Rainier Ave. Mixed Use Project, 559 to 625 Rainier Ave. North, Renton, R'ashington"; for Mr. Jack ! 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'.i ; �-Y.-�.. r�a I� � bcc� � � �� �1�1 �� 1 ,_ :! _~~t �S �.. I �� ��.�..-�. �{�� /!�i(': _ ���� � - ':� - — _-- 1t,1 ��� IFark f:_ ,���_S \_ _.._ I �T 0 1/2 lmile lr ' approximate graphical scale USGS 7.5 MINUTE QUADRA:'�GLE RENTON,WA-REVISED 1994 SCALE 1:24 000 CONTOUR INTERVAL 25 FEEI' , � Rainier Avenue Mixed Use Project � �� The Riley Group, Inc. I 10728 LAKE C1T'Y WAY NE Site T�icinity Map Figure 1 SEATTLE,V1 ASHINGTON 98125 Site Address:559 -625 Rainier Avenue N., Renton,Washington d' �� � 0 =-� � ' ,; � f� �� �` ''� �t rj � � � , _ • lf � ; i' �` ���� / � r` 1 s� � ���"_, �' �•' �� i % �a:.mco� Y��"� ' �ja' ,.- - i .,,.�..i •',•���' f�� f;�. � \ TP� `�� � j: '� �}. j`� �`'� Legend "d - �f�r'� . M�t t' .�� � {,,�, Y���1+ � �'� '��# ;=� /'� TP-� � ; Test pit locations by Riley 7-11 April - �f� � ;�'� `��,r-�`� � 2003 (TP-1 through TP-12) t� ,� � �"� s' � i ,��- � .��, J�J l �� r+ : Boring locations by Riley 17-19 April r � �' I � ��,..�� � < 2003 (B-1 through B-4) � l• � ;-� ,� -.� � B-2 TP-2�` �� B-1 v - ' p'f � `�� � : ��a - � I � � ,�_-,° ,,� �-, r .�-� u !� f' { "�zea.00' � ' ""' Monitoring well Iocation by Riley 19 f . i j : ` `� � Marc h 2 0 0 1 (M W 1 an d M W 2) TP-5 f f _ ! _: _ _ _ i _ _�_ � f � _ � , � n : TP-�� TP-9 �1 � ca � -�- �o � i B-3 � TP-3 333.75' _ �. 53.25' .� _ � �. : ,; P-11 � , 5 ;., � ,_, _. ___ : ; �;. � �� - „_. , .` _ - _� � . :' � �.. � . � - i TP-7' �-a� * .�'� : CNK�Auto �'� ��' i TP-12� 3 °� ' , �� '`-',, ; � 559 Rai ie� Aae. N � °� � � ; t�3 TP-S .• . , . � •a�.. . _ � � � � ! � j � •. Y 1_.�• . ..i• a � _.3..__ r •..._i i • .""i 'I' • ' "� �"'Y v" . ..._....___ _. �'` . � � � � ._ ..... � ' � - � = •__.�,ll a \ R,. ..._ • f.___A.�.. i. 0 ! O .1....:• A.[�...� _ _ • . .. � . . �.. � � �� \ � � �:s,-• •�;•�;. '�• ,, + ;a �� � � 4 � d. �-. . ..-.ti.�:�.°�,;. � P - ' , ;.�,_,..�.- . �.� y y se R� ' � � i � �- . : ` O� ��. ` ' s� j � � • -�x _.,_, ..- �Re�eton-Au#o_Gentar._:: �� " ��o�' �� ~ i MW-2 I � 6a1 Rainier Ave. N �- TP� � 6'�y � ���`���.'�a������.\�ti�.�.���.,'�:����,'���� ' a MW-1 � � ` r _ _ __ . : _ _ ____ _ - _ ___ . _ ._._.__ _ _ ; __ _ ___ � . �� , �' B-4 �,{ o , .,�-e. +u�w �' � — _..,� w::.t._��-`'v� , �. € _ _ _ � . –.., _ t .. � - . .-... _ _ a�, �� ---�,._-- � �� � y .~ �.._ _ t' i_' , ~� V _ , � ,. - 1 V -------_._ � � ,, i�W __� � –.._. ___._� __.__.. .._._._... .__._._... ._ _ __.__...._---. ___._. _,____.__. .___ ___ . .._,_._ __._. . _..._. __..____ _ _____._ _ - -- - __ _. _ _. _ _ , _ _. _._._.._ r{� x�rc�v�xira � a -��---�— �_,...,,� �� fs nN iuu��em��irie vwl n ana��lL�MVtl L,. �"".�--.-_-'----"- �¢ ""„^--�__� — �_`..._, � � �� � = RAINIER AVENUE N. �___y�' _� � � Graphical Scale:t"=60' _ __ _ _ _ _ _ _ __ Reference: Survey& Site Plan(for Rainier Avenue Mixed Use), � The Riley Group, ItZ� Rainie�Avenue Mixed Use ProjecZ by Baylis Architects, dated Ol April 2003 10728 LAKE CITY WAY NE Site and Exploration Plan Figure 2 SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier Avenue N.,Renton,Washington ; � � � i — � ' � � �`� � � ��� � � �_ � 7 ' � 1 � . � ��� � ' ` � � � � s � � � . � '° � �' ' s 'O , � �s / � �6 � '� , '� , ���� � . �� ,# , � � �� _ . � � o - � ,. _ -� � ;��� � � � �� � � - - i� s° _ ' • �, __ —_. " � � � �\ _ � - - - -,—,�• �� � �'�' � � ' � . ., � b '� i ' y � �� o � � �` • � 4 � �� ti i� " ' t �� i �� : �, '�� : ,} _ .�.1.-c�.` I� � '�:�,, '�:�;_� �t" ; � / '_ / '��. t 'I����1-��� �t.Yr. ��`�/�Ir� � .� ' / � i � d �!� � , � ~•I ' • �� -/ �''~�1+/ ' � � ' � �C �� O p��� �+ � �` � �� i , � 4 g ' , :� ' � � te � .. � _ F. " � L � i v .� '! � p '� • ' i� r - //� � ,� � 'r , � ____, ' ._-. –,– ;;',.� � ? — ��'" . .. ��=�u� .�' ��"" O � ` � d � 1 � — 1 �� � � i` ea �sa �. �� � � N nE 4 � t _�. „� � i_ � Graphical Scale: t" a � 4 v �. ' Reference: Boun & To o ra hic Surve "Rainier Avenue Mixed Use", Rainier Avenue Mixed Use Project � P g P Y � The Riley Group, In� by Triad Associates, dated 26 September 2002 10728 LAKE CITY WAY NE Topographic Site Plan Figure 3 SEATTLE,WASHINGTON 98125 Site Address: 559-62� Rainier Avenue N.,Renton,Washington i i i BIJILDING SLAB � - . .�� . � ; " . ; • ': . �,� �� - �: a �:- ...:� .�.<-�:: :.: :. _� � �/����\��\�i ' . .�• ' ' ' ' •' •. -:_.'" '':- •.- • ;••.:.,�..�: ? �� . . �.y L� `r���..i*: ���L.�y.•y:Y'ti�.-.r`M1 / �� �/� �� /� � .. 1 , �, titi-�.a+':�.:...~�_���.-.:�.`��. :.:i`. �� ;�`-`�COIvIPAC"TED.'� .•' ��' �, \ •,d vf:�;_���_ . . .:- ,�. •. . •',..::,:.:STRUC'I'[JRAI1�::= :�, � ' ' '�' �:�';`�'.�-:BACKFILI�'-:w- �� ` ' ��. ��, �'�'.e� ,':::- ��.L�-'a��: '� � � . �=;:_=�:- :-�:- :�;�L.:�=; FILTER � , . � � `..� '. � FABRIC ��\. "�.�'L. �t.t.. . � 1t�+^J�:,l� �..•�L�~ /�/ �/ � a. �:, N�<< : ::� " �... ��� .� , . .. . . * :• .� -: .:• , O O �� � j �'� . ' .. � • ` . j. � � �� 'd �. �\� � � • • ' d'' � '�. \ ` , • •. � d \\ �' /� /\ /\ /\ /\ /\ /\ /\ / �/ � 4"PERFOR.ATED PIPE I 3/4"WASHED ROCK OR PEA GRAVEL � � NOT TO SCALE I I I Rainier Avenue Mixed Use Project �� The Riley Group, I�c. I 10728 LAKE CIT'1'Vl'AY NE 7'ypical Footing D�-ain Detail Figure 4 SEATTLE,Vb'ASHINGTON 98125 Site Address: 559-625 Rainier A��enue N.,Renton,Washington i i I 12" i�INIt�UM WIDE FREE—DRAINING GRAVEL ' SLOPE TO DR�4tN � � � 12" I�IN. � �' . � .. ' ;o ..- : • o� . -_ .d� . , • , .� • . , . I �� . - , . : ... �,. �e s . :p • . ' • . . � . FlLTER FABRIC I�ATERIAL °s• ''• : • � .. .' •• .. �a . : - IXCAVATED SLOPE � ;,o � . � : • .- • : ' .. '. (SEE REPORT FOR °oa ' :. ' • . -� '." - APPROPRIATE 0 0 • • .. .' • _ " . � INCLINATIONS) I d � .: . ..• • . : . o•$ . . _ COMPACTED STRUCTURAL •�, -' :. - - BACKFILL (NAl1VE OR �' ' •- .. .. �� ' :.�� IMPOR� �o, � .• .. � �880�.p�cc•ooe; poo,poo •eC!'io�a0�a0as�y��^O •. ♦ � � � 12' OVER THE PIPE 4' DWuIEfER PVC 3" BELOW THE PIPE � PERFORATED PIPE � - N OT T 0 SCA�E I I � I � I Rainier 14venue Mixed Use Project , �' Tlie Riley �roup, Inc. � 10728 LAKE CITY WAY NE Retaining Wall Drainage Detail Figure S I SEATTLE,WASHINGTOA'98125 Site Address:559-625 Rainier Avenue N.,Renton,Washington �� EARTH PRESSURE DESIGN PARAMETERS FOR SOLDIER PILE CANTILEVER WALL - I-I/2H:IV BACKSLOPE i-i/2 I , � �� 60 pcf � — Q-- � ' �, � Passive Earth II I) Pressure = 200 pcf I) I) 15 pcf over 1 pile diameter � taken over 2 pile � below base of excavation diameters I Note: Value includes (I II Sofety Factor of 1.5. � � � Passive I Active � � I N OT TO SCALE I Note-Active pressure taken over full center-to-center pile spacing above base of excavation IActive pressure taken over 1 pile diameter below base of excavation Passive pressure taken over 2 pile diameters below base of excavation I Rainier Avenue Mixed Use Project ' The Riley Group, Inc. � 10728 LAKE CITY WAY NE Shoring Pressure Diagram Figure 6 SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier Avenue N.,Renton,Vl'ashingwn i i ' WOOD LAGGING I :. - I � ••. '.: . CONCRETE FACING .• a �; .. ' a :� �, . • � � j'(� � CONTINUOUS MIRADRAIN 6000 OR ' J1t . �! � ' •� - EQUIVALENT ' . •a — :.. '�, • , , .:�' •� '� �. NATIVE SOIL • •a . SLAB-ON�RADE FLOOR EXCAVATION • . � •.� •. , '.. .. ; ,a�:, . ' . , • ' � 'f ' ./. ' : `�. .• . .•. . ' . . . , e. � . • � .. . �.. '. � . ,'' . • . a . , • , �' . , a• � . � � . . • 6� � � '' • • . . .'.._'.'.'.'."_'. '.'.'.'.' , �� ' ai. �� • .�.�_...�.�.�.�..�. �..�..� . PVC 7'IGFiT'LINE '.'.'.'.'.'.'.'.'.'.:'.' .'.'. ..................... ` • � . ' .. '.".".'STRUCTURAL.".'. � � , • ' . ° ! a ' .� '.'.':. ' ....FILL _:. I r � . � .. • '�, . . '.':.".'. '.'.'.'. :.":.'.' I ' � ! ' � •...... ' ..... � ¢ '. ' • ' �. • . .. ..'.'.'.'.':. •••• '•'•'•'•'• .. . , • - . .- .°FOUNDATION. .....:.:.:.:'.'.'O_'.'.:...'.-'' '.'.'.'.'.'' II DRAIN GRATE . � . . ...... ... . . ..... . : . . .' ' a .................... ...•- . � , • . '. ............... ..... ..... . , . , . .................... ..... I . •. ., : • . '.......... H �.. , . . .. ...... a' %• ' • • ' � I ,� , : a' � • . �, . � TF—i ir NOTE: DRAIN THROUGH WALL SHOULD BE INSTALLED AT MIDDLE OF LAGGI NG. ' ' � Rainier Avenue Mixed Use Project �� The Riley Group, Inc. ' i o�2a r�crrY waY rrE Typical Wall Drainage Detail Figure 7 SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier Avenue N.,Renton,Washington I MAJOR DIVISIONS LETTER TYPICAL DESCRIPTION SYM BOL GRAVELS CLEAN GW e -gra e grave s, gra�e-san mix ures, i e or no fines. � �, More than 500�o GRAVELS Poorly-graded gravels, gravel-sand mixtures, I.i� � of coarse �5% fines GP Iittie or no fines. Z � a� Silty gravels, gravel-sand-silt mixtures, .L � fraction is GRAVELS GM non- lastic fines. � 'u� larger than No. Cla e ravels, ravel-sand-cla mixtures, � J � 0 4 sieve W�th fines GC Y Y 9 9 Y (� _ o N lastic fines. I � � �o Z SANDS SANDS SW nes 9raded sands, gravelly sands, little or no � � c More than 50% Paorly-graded sands or gravelly sands, little or O � ..��. of coarse �5% fines SP no fines. U o fraction is SANDS SM Silty sands, sand-silt mixtures, non-plastic fines. � smaller than With fines ; 'i No. 4 sieve SC Clayey sands, sand-clay mixtures, plastic fines. � norgarnc si s, roc our, c ayey si wi s ig p �� �� SILTS AND CLAYS M� plasticiry. W norganic c ays o ow o me ium p as ici , ean � � Liquid limits CL cla . z o Y) I � � `�' less than 50% � � o Z �L Organic silts and organic clays of low plasticity. � � W � .� � SILTS AND CLAYS MH Inorganic silts, elastic. � z � � Liquid limits greater CH Inorganic clays of high plasticity, (fat clays). � � � than 50% N �H Organic clays of high plasticiry. I HIGHLY ORGANIC SOILS PT Peat. DEFINITION OF TERMS AND SYMBOLS � L J Densi SPT (Blows/Foot) 2�� Outside diameter split spoon O W Very loose 0-4 Z sampler p � Loose 4-10 � Z � Medium dense 10-30 2.4" Inside diameter ring sampler or Q Dense 30-50 � Shelby tube � � Very dense >50 � Water level (date} , Consistency SPT (Blows/Foot) Tr Torvane reading, tsf , L Very soft Q-2 pp Penetrometer reading, tsf � � >- Soft 2-4 pp Dry density, pcf J J Medium stiff 4-8 �� Liquid limit, percent � U Stiff 8-16 p� Plasticity index I Very stiff 16-32 N Standard penetration, blows per foot Hard >32 I Rai��ier Ave�zue Mixed Use Pf�oject I Tlze Riley Group, Ijic. � 10728 LAKE C1TY 4t-AY NE Unified Soil Classification System Figure�4-1 SEATTLE,WASHINGTON 98125 I Site Address:559-625 Rainier Avenue'_v.,Rencon,Washington i � Boring No. B-1 � I . Logged by . GJ K Date: 4/17/03 Approximate Elev.: 97' � Consistency/ �' (N) Moisture Relative De th °" � Soil Description P E Blows Content Density (feet) � /ft (%} I Brush, topsoil Silty sand, grey-brown, fine to coarse, with some gravel, Very Dense 55 moist, very dense, (SM), TILL 5 82 12.3 Sand, grey, fine to coarse, trace gravel, moist, very Very Dense 50/6" dense, {SP) Sandy gravel, grey, fine �� gravel, fine to coarse sand, Very Dense 50/6" moist, very dense, (GP) Very Dense 50/5" Silty sand, grey, fine to �� I coarse, with some gravel, �, moist, very dense, tSM) ' 50/4" �� The Riley Group, InC. Rainier Avenue Mixed �Ise Project 10728 LAKE CITY WAY NE Test BoYing Log B-1 Figure A-2 SEATTLE,WASHINGTON 9812� Site Address: »9-625 Rainier Avenue N.,Renton,Washington i �, - Boring No. B-1 �Cont.) � I � Logged by : GJK I, I Date: 4/17/03 Approximate Elev.: 97' ', Consistency/ � (N) Moisture �I � Soil Description Relative Depth � Blows Content '� Density (feet) � �ft t%� ', i � II � � i Very Dense 50/5" 10.4 � �I I 25 � Silty sand, grey, fine to ,� coarse, with some gravel, 50/3 moist to wet, very dense, (SM) � 30 � � 50/5" I 35 � 50/4" � �4/18/43) � � I Rainier�Avenue Mixed Use Project �� The Riley Group, Inc. I 10728 LAKE CITY WAY NE Test Boring Log B-1 Figure A-3 SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier Avenue N.,Renton,Washington i Bori ng No. B-1 (Cont.) - I Logged by : GJK ' Date: 4/17/03 Approximate Elev.: 97' Consistency/ a (N) Moisture � Soil Description Relative Depth � Blows Content Density (feet} � fft �o�o� � � Sandy silt, grey, with red-brown mottling, fine sand, Very Dense 50/5" 17.8 with some gravel, wet, very dense, {ML) 4� = 50/5� Bottom of boring at 48 feet Depth of water at 38.2 feet on 18 Apr. 2003 50 Observation well installed to 48 feet I screened from 48 to 43 feet sand from 48 to 38 feet bentonite seal at 38 feet I 55 � � I �I � IRainier Avenue Mixed Use Project �� The Riley Group, I�z� � 10728 LAKE CITY N�AY NE Test Boring Log B-1 Figure�1-4 SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier Avenue N.,Renton,Washington ' Boring No. B-2 I Logged by : GJK I Date: 4/18/03 Approximate Elev,: 93' Consistency/ a (N) Moisture � Soil Description Relative Depth � glows Content Density (feet) � �ft (%} I Brush Sand, grey, fine to medium, � with some silt, with some gravel, moist, very dense, Very Dense 50/6" I (SP/SM) 5 I Very Dense 50/6" 12.1 � 50/6" Silty sand, grey-brown, fine to I coarse, with some gravel, 10 moist, very dense, (SM) 50/4" � I 50/3�� I 15 � = 50/3" Bottom of boring at 18 feet � No groundwater encountered � I Rainier Avenue Mixed Use Project r� The Riley Group, Inc. I 10728 LAKE CITY WAY NE Test Boring Log B-2 Figure A-S SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier Avenue N.,Renton,Washington Boring No. B-3 . I Logged by : GJK Date: 4/18/03 Approximate Elev.: 48' Consistency/ a (N) Moisture Soil Description Relative Depth � Blows Content Density (feet) � �ft �o�o� I Gravel fill Silty sand, dark brown, fine to � coarse, with some gravel, Medium pieces of charcoal, moist-wet, Dense �� I medium dense, (SM), FILL 5 � I Sandy silt, grey, fine sand, with wood fragments, wet, Loose 7 loose, (ML), FILL � 10 , I Obstruction zone starting - 11 ft Silty sand, grey, fine to coarse, with some gravel, wet, (SM),FILL I Sampled on obstruction / Blow 50/4" ' count not valid, possible auto debris or wood 15 No recovery / Sampled on 50/4" obstruction blow count not valid � (4/18l03) Silty sand, grey-brown, fine to medium, with organics (roots, Medium 16 I wood fragments, peat pockets), Dense wet, medium dense, {SM) � � Rainier•Avenue Mixed Use Project �� The Riley Group, Inc. 10728 LAKE CITY WAY NE Test Boj�ing Log B-3 Figure A-6 SEATTLE,WASHINGTON 98125 Site Address: 5�9-62�Rainier Avenue N.,Renton,Washington i Boring No. B-3 (Cont.) I Logged by : GJK I Date: 4/18/03 Approximate Elev.: 48' Consistency/ � (N) Moisture Relative De th �" � Soil Description P E Blows Content Density (feet} � �ft (%) I (Silty sand - continued) 30 I - 6 inch peat layer at 23 ft Medium Dense 22 � - with peat layers up to 3 inch 25 I thick � - 6 inch peat layer at 28 ft 20 88.1 � 30 � - fine to coarse sand, with I some gravel Dense 35 I 35 i Silty sand, grey, fine to medium, with some gravel, moist, medium dense, (SM} Medium 23 I Dense � � ' The Riley Group, Inc. Rainiej�Avenue Mixed Use Project ' 10728 LAKE CITY Vti'AY NE Test Boring Log B-3 Figure A-7 SEATTLE,WASHINGTON 98125 Site Address: 559-625 Rainier A��enue N.,Renton,Washington Boring No. B-3 (Cont.} Logged by : GJK Date: 4/18/03 Approximate Elev.: 48' ; Consistency/ Q (N) Moisture � - Soil Description Relative Depth � Blows Content Density (feet) � �ft �o�o� Very Dense 50/6" Silty sand, grey-brown, fine, 4� � moist to wet, very dense, (SM) 93 I Bottom of boring at 49 feet 50 Depth of water at 17 feet at time of drilling 55 � The Riley Group, I�2e. Rainier Avenue Mixed Use Project 10728 LAKE CITY VVAY NE Test Bof�ing Log B-3 Figure A-8 SEATTLE,WASHINGTON 9812� Site Address: 559-b25 Rainier Avenue I`.,Renton,Washington I � Boring No. B-4 � Logged by : GJK ! Date: 4/19/03 Approximate Elev.: 50' ', Consistency/ a {N) Moisture ' Soil Description Relative Depth � Blows Content Density (feet) � �ft ���o� Asphalt Silty sand, grey, fine to medium, with some gravel, Dense 44 moist, dense, {SM), FILL 5 47 46 10 Medium 15 Silty sand, mottled grey and Dense brown, fine to medium, with some gravel, moist, medium dense, (SM), FILL 13 15 Sandy silt, grey with brown mottling, fine sand, with some gravel, moist, medium dense, (ML) Medium 50/3" ? Sampled on gravel, blow count Dense not valid �� The Riley Group, In�. Rainier Avenue Mixed Use Project 10728 LAKE CITY WAY NE Test Boring Log B-4 Figure A-9 SEATTLE,WASH[NGTON 98125 Site Address: �59-62�Rainier A�-enue N.,Renton,Washington � � - Boring No. B-4 (Cont.) I Logged by : GJ K I Date: 4/19/03 Approximate Elev.: 50' Consistency/ � (N) Moisture Relative De th a' � Soil Description P E Blows Content Density (feet) � �ft (%} � Silty sand, grey, fine to ' � medium, with some gravel, Medium ' occasional layer cleaner sand, 25 occasional layer sandy silt, Dense � very moist, medium dense, �SM� 25 � � Peat, dark brown, fibrous, with Stiff 22 167.3 '� non fibrous layers, with silty , peat layers, moist, (Pt) �, 30 I � (4/19/03) � I - with some layers silt to sandy I silt � 21 I 35 � Sandy silt, grey, fine sand, Medium trace wood fragments, moist, Dense 26 � medium dense, (ML) � I Rai�zier Avenue Mixed Use Project � The Riley Group, I�zc. I 10728 LAKE C1TY WAY NE Test Boring Log B-4 Figure A-10 SEATTLE,WASHlNGTON 98125 Site Address: �59-625 Rainier Avenue N.,Renton,Washington i Boring No. B,4 (Cont.) - I Logged by : GJK I Date: 4/19/03 Approximate Elev.: 50' Consistency/ � (N) Moisture Relative De th �' � Soil Description P E Blows Content I Density (feet) � /ft (%} � � - wet, dense Dense 40 � 45 � � Silty sand, grey-brown, fine, Very Dense 78 moist, very dense, (SM) � 50 � - fine to medium sand, wet I 70 Bottom of boring at 54 feet 55 � Depth of water at 31 feet at time of drilling � i � � � �� The Riley Group, It2C. Raitzier Avenue Mixed Use Pf•oject I 10728 LAKE CITY 4l�'AY NE Test Boring Log B-4 Figure A-I1 SEATTLE,WASHINGTON 9812� Site Address: 559-625 Rainier Avenue I�.,Renton,Washington Logged By: GJK Date: 417/03 Test Pit No. Depth (ft) Soil Description Sample TP-1 0.0 - 0.3 Duff, topsoil depth (moisture} 0.3 - 2.5 Silty sand, light brown, fine to coarse, with 1 ft (14%} some gravel, moist, medium dense, (SM) 2.5 - 6.0 Silty sand, grey, fine to medium, with some 5 ft gravel, moist, medium dense to very dense, (SM), TILL Bottom of test pit at 6 feet No seepage encountered No caving TP-2 0.0 - 0.5 Duff, topsoil 0.5 -4.0 Silty sand, light brown, fine to coarse, with 2 ft(12%) some gravel, moist, medium dense, (SM) 4.0 - 6.0 Silty sand, grey, fine to medium, trace 5 ft gravel, moist, medium dense to very dense, (SM), TILL Bottom of test pit at 6 feet , No seepage encountered I No caving TP-3 0.0 - 0.2 Duff, topsoil 0.2 -4.0 Silty sand, brown, fine, moist, very dense, 3 ft (SM) Bottom of test pit at 4 feet ' No seepage encountered I No caving r� The Riley Group, Inc. Rainie�Avenue Mixed Use Project 10728 LAKE CITY WAY NE 7'2St Plt�OgS Figure A-12 SEATTLE, WASHII�TGTON 9812� Site Address: 5�9 - 62� Rainier Avenue N., Renton, WA Logged By: GJK . Date: 4/7103 �- Test Pit No. Depth (ft) Soil Description Sample TP-4 0.0 - 2.0 Silty sand, dark brown, fine to medium, depth (moisture} trace gravel, with roots and branch pieces, 1 ft moist, loose, (SM) 2.0 - 4.0 Silty sand, light brown, fine to medium, with 3 ft some gravel, trace roots, moist, medium dense, (SM) 4.0 - 6.0 Silty sand, grey, fine to medium, with some 5 ft gravel, moist, very dense, (SM}, TILL Bottom of test pit at 6 feet No seepage encountered No caving TP-5 0.0 - 0.2 Duff 0.2 - 5.0 Sand, light brown, fine to medium, with 3 ft some silt, moist, medium dense, (SP/SM) 5 - 13 Sand, light grey-brown, fine to medium, 6 ft (11%) with some silt, moist, medium dense, (SP/SM) Bottom of test pit at 13 feet No seepage encountered No caving TP-6 0.0 -4.0 Silty sand with gravel, mottled grey, fine 2 ft (4/9/03} to coarse, occasional wood debris, moist, medium dense, (SM), FILL 4 - 14 Silty sand with gravel, mottled grey, fine 14 ft to coarse, moist, medium dense to dense, (SM), FILL Bottom of test pit at 14 feet ' Moderate seepage at 4 feet , caving below 4 feet �� The Riley Group, Inc. Rainier Avenue Mixed Use Project 10728 LAKE CITY��VAY NE Test Pit Logs Figure A-13 SEATTLE, WASHINGTON 9812� Site Address: »9 - 62� Rauuer Avenue N., Renton,WA B : GJK Date: 4/11103 II Logged y , Test Pit No. Depth (ft) Soil Description Sample I', TP-7 0.0 - 1.5 Sandy silt, dark brown, fir�e sand, with some depth (moisture} �, gravel, with roots and organics, moist, 1 ft �, loose, (ML} , 1.5 - 6 Sandy silt, light brown, fine sand, moist, 3 ft (25%) ! hard / very dense, (ML) � 6 - 7 Sandy silt, grey, fine sand, moist, hard / 7 ft (25%) ', very dense, (ML) ' Bottom of test pit at 7 feet Minor seepage at 6 feet No caving TP-8 0.0 - 0.2 Gravel 0.2 - 4 Silty sand, brown, fine to coarse, with some 2 ft gravel, with bnck fragments, moist, medium dense, (SM), FILL 4 - 12 Silty gravelly sand, brown and grey, fine to 12 ft coarse, occasional roots, moist, dense, {SM/GM}, FILL Bottom of test pit at 12 feet No seepage encountered No caving r� The Riley Group, Inc. Rainier Avenue Mixed Use Project 10728 LAKE CITY WAY NE Test Pit Logs Figure A-14 SEATTLE,WASHINGTON 9812� Site Address: ��9 - 625 Rainier Avenue N., Renton, WA Logged By: GJK . Date: 4/11/Q3 Test Pit No. Depth (ft} Soil Description Sample �I � TP-9 0.0 - 0.5 Topsoii, duff depth (moisture) � i I 0.5 - 2 Siity sand, grey-brown, mottled red-brown, 1 ft fine to coarse, with some gravel, trace roots, moist, loose, (SM}, FILL 2 - 5 Silty gravelly sand, grey, fine to coarse, 3 ft moist, loose, (SMIGM), FILL � 5 - 13 Silty gravelly sand, grey-brown, fine to 13 ft �I coarse, with wood, auto debris, tires and 'I trash, moist, loose, (SM/GM), FILL � Bottom of test pit at 13 feet � No seepage encountered iModerate caving TP-10 0.0 - 0.5 Topsoil 0.5 - 2 Sandy silt, brown, fine sand, with some 1 ft (19%) gravel, with roots, moist, hard, (ML} � 2 - 4 Silt, light brown, moist, hard, (ML) 3 ft(30%) 4 ft(33%) Bottom of test pit at 4 feet No seepage encountered No caving TP-11 0.0 - 0.5 Topsoil 0.5 - 1 Sandy silt, light grey-brown, fine sand, 1 ft (24%) moist, loose to medium dense, (ML) 1 - 4 Sandy silt, light brown, fine sand, moist, 3 ft {23%) hard /dense, (ML) Bottom of test pit at 4 feet No seepage encountered No caving rr The Riley Group, Inc. RainierAvenue Mixed Use Project 10728 LAKE CITY WAY NE Test Pit�ogs Figure A-I S SEATTLE,WASHINGTON 98125 Site Address: »9 -625 Rainier Avenue N., Renton,WA Logged By: GJK Date: 4/11103 Test Pit No. Depth (ft) Soil Description Sample 'I TP-12 O.Q - 0.2 Topsoil depth (moisture) ', 0.2 - 4 Silty sand, light brown, fine to medium, with 3 ft (11%) �, some gravel, moist, dense, (SM) �I Bottom of test pit at 4 feet �' No seepage encountered ' No caving ', � The Riley Group, Inc. Rainier Avenue Mixed Use Project 10728 LAKE CITY WAY NE Test Pit Logs FiguYe A-16 SEATTLE,WASHINGTON 9812� Site Address: »9 -62� Rainier Avenue N., Renton,WA i � I - Boring No. MW-1 Logged by : TF I Date: 3/19101 Approximate Elev.: 50' Consistency/ � (N) Moisture Soil Description Relative Depth � Blows Content Density (feet) � �ft �o�o� Asphalt Silty sand, grey, fine, with some gravel, dry, very dense, Very Dense 58 (SM) 5 Silty clay, grey, moist, stiff, (CL) Stiff 16 10 Silty sand, grey, fine, with some gravel, dry, dense, (SM) Very Dense 50/1" Sampled on a rock 15 � (4/3/03) Silty clay, grey, moist, stiff, (CL) Stiff 14 r� The Riley Group, I�zc. Rainier Avenue Mi.�-ed Use Project 10728 LAKE CITY WAY NE Monitoring Well Log MW-1 Figure�1-17 SEATTLE,WASHINGTON 98125 Si[e Address: 559-625 Rainier Avenue N.,Renton,Washington I i Boring No. MW-1 (Cont.) - I Logged by : TF Date: 3/19/01 Approximate Elev.: 50' Consistency/ °� (N) Moisture Relative Depth �" Soil Description E Blows Content Density (feet) � �ft �o�o� No recovery, sampled on a rock 24 25 � (3/19101) I Silty clayey sand, grey, wet, Dense 37 dense, (SM) � 30 � Very Dense 50/6" 35 Bottom of boring at 35 feet Monitoring well installed to 35 feet Depth to water: 27 ft on 19 Mar. 2001 17.3 ft on 03 Apr. 2003 �� The Riley Group, IM�. Rainier Avefzue Mized Use Project 10728 LAKE C1TY WAY NE Monitoring Well Log MW-1 Figure A-18 SEATTLE,WASHiNGTON 98125 Site Address: 559-625 Rainier Avenue V.,Renton,Washington Boring No. MW-2 I Logged by : TF Date: 3/19/01 Approximate Elev.: 48' Consistency/ � (N) Moisture Soil Description Relative Depth � Blows Content Density (feet} � �ft �o�o� Asphalt Gravelly silty sand, grey, Medium �$ damp, medium dense, (GM) Dense 5 26 10 Gravelly silty sand, grey-brown, damp, very dense, (GM) Very Dense 50/6" 15 Silt, grey-brown, dry, hard, (ML) Hard 50/6° �� The Riley Group, I�2C. Rainier Avenue Mixed �Ise Project 10728 LAKE C1TY V✓AY NE Monitoring Well Log MYV-2 Figure A-19 i SEATTLE,WASHINGTON 9812� Site Address: 5�9-625 Rainier Avenue N.,Renton,Washington - -� Boring No. .MW-2 (Cont.) Logged by : TF Date: 3/19/01 Approximate Elev.: 48' � Consistency/ a (N) Moisture I Soil Description Relative Depth � Blows Content Density (feet) � �ft �o�o� , � � (4/3/03) � (3/19/01) Very Dense 50/5" 25 Sand, grey, fine, wet, very dense, (SP) 50/6" 30 Bottom of boring at 30 feet Monitoring well installed to 30 � feet Depth to water: � 23 ft on 19 Mar. 2001 21.3 ft on 03 Apr. 2003 35 � � I Rainier Avenue Mixed Use Project ' The Riley Group, Inc. 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