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HomeMy WebLinkAboutWWP273549HWAGEOSCIENCES INC. February 2, 2011 HWA Project No. 2009-058-21 Task 3 Carollo Engineers 1218 P Avenue, Suite 1600 Seattle, Washington 98101 ' Attention: Ms. Lara Kammereck, P.E. SUBJECT: FINAL GEOTECHNICAL EVALUATION REPORT East Renton Lift Station Elimination Renton, Washington ' Dear Ms. Kammereck: As requested, HWA GeoSciences Inc. (HWA) has undertaken a geotechnical investigation to ' evaluate the subsurface soil conditions associated with the subject project. Our investigation consisted of performing site explorations, laboratory testing, geotechnical analyses, and preparation of this report. The field exploration program consisted of test pits at selected locations. Soils information obtained from our field exploration and laboratory testing was used to develop the recommendations provided herein. PROJECT DESCRIPTION We understand that the City of Renton (City) is proposing to eliminate the East Renton Lift ' Station, located to the north of the right of way of SE 136th Street in Renton, Washington, as indicated in the attached Vicinity Map, Figure 1. Previous studies have determined that elimination of this lift station would require the construction of a gravity sewer line linking the in ' flow to the current lift station to an existing sewer system to the south. To best facilitate this connection, the proposed alignment would extend from the existing lift station, through Maplewood Park, and connect to the City's existing sewer system near the northern terminus of ' 148th Place southeast. Given the site topography, it is our understanding that trench excavations ranging from 7 to 12 feet deep will be required to maintain the desired gradient along the ' alignment. The proposed alignment through Maplewood Park, as shown in the Site and Exploration Plan, Figure 2, will require a small creek crossing located just to the south of the existing lift station. It is our understanding that both open trench and trenchless construction methodologies are being considered for this crossing. SITE CONDITIONS The existing temporary sewer lift station is situated on the north side of the 21312 30th Drive SE right-of-way for SE 136th Street, which presently remains undeveloped in the Suite 110 segment extending from the also undeveloped right-of-way for 148th Avenue SE Bothell, WA 98021.7010 ' Tel: 425.774.0106 Fax: 425.774.2714 wwwAwageo.com February 2, 2011 HWA Project No. 2009-058-21 Task 3 to the west and 152❑d Avenue SE to the east. The lift station occupies the southwest corner of an existing storm water management pond site that apparently was constructed in conjunction with a residential neighborhood development to the north and east. The existing SE 136th Street right-of-way contains other underground services such as water and gas lines that run in an east - west direction within the right-of-way south of the lift station. Existing east -west sanitary sewer lines connect with the lift station at the present time and also trend east -west in alignment. The proposed sewer line alignment follows established trails through the majority of the heavily forested park. The topography along the proposed alignment generally slopes to the south while crossing a modest draw and a seasonally varying creek. The northern portion of the alignment runs parallel with a pressure gas line and the proposed alignment crosses the gas line approximately half way through the park. GEOLOGY According to the Geologic Map of King County, Washington, by Derek P. Booth, and Aaron P. Wisher (Booth et al, 2006) the site is underlain by glacial till soils deposited sub -glacially from the Vashon Ice Sheet. The glacial till has been over -ridden by glacial ice and is very dense and concrete -like as a consequence, in its un-weathered state. When exposed at surface, however, the upper 3 to 5 feet is cormnonly weathered and less dense. In view of the forest setting of the alignment, it is evident that a surficial topsoil and organic duff layer overlies the glacial till, and it is anticipated that the wetlands features will contain variable thicknesses of organic peaty soils near -surface. FIELD EXPLORATIONS Subgrade soils along the proposed alignment were explored through the excavation of six test pits, completed on December 2, 2010. The test pits, designated TP-1 through TP-6, were advanced along the proposed gravity sewer alignment, at the approximate locations shown on Figure 2. The depths of the test pits ranged between 4.5 and 10 feet below ground surface (bgs). An abandoned, 400-pair, Quest phone line was inadevertantly encountered at 3.5 feet bgs in test pit TP-1. Subsequent conversations with Quest revealed that alive 600-pair, abandoned 400-pair, and abandoned 200-pair phone lines are located within close proximity to the location of TP-1. The test pits were excavated by the Glenbrook Services, with a Kubota KX-121 rubber tracked excavator, and logged by an HWA geotecluzical engineer. Soil samples obtained from the explorations were classified in the field and representative portions were placed in plastic bags and returned to our Bothell, Washington, laboratory for further examination and testing. On completion, the test pits were backfilled with the excavated spoils, then tamped with the excavator bucket and a jumping jack compactor. However, some future settlement at the test pit locations should be expected. A Legend of Terms and Symbols Used on Exploration Logs is presented on Figure A-1, in Appendix A. Summary soil exploration logs are presented on Figures A-2 through A-7. It IFinal Letter Report 2 HWA GeoSciences Inc. February 2, 2011 HWA Project No. 2009-058-21 Task 3 should be noted that the stratigraphic contacts shown on the individual exploration logs represent the approximate boundaries between soil types; actual transitions may be more gradual. Moreover, the soil and ground water conditions depicted are only for the specific date and locations reported and, therefore, are not necessarily representative of other locations and times. LABORATORY TESTING Laboratory tests were conducted on selected soil samples to characterize relevant engineering properties of the on -site subsurface materials. The laboratory testing program was performed in general accordance with appropriate ASTM Standards as outlined below. Moisture Content of Soil: The moisture content (percent by dry mass) of selected soil samples was determined in accordance with ASTM D 2216. The results are shown at the sampled intervals on the test pit logs in Appendix A. Particle Size Analysis of Soils: Selected samples were tested to determine the particle size distribution of material in accordance with ASTM D 422. The results are summarized on Figures B-1 and B-2, which also provide information regarding the classification of the samples and the moisture content at the time of testing. SUBSURFACE SOIL CONDITIONS Our interpretations of subsurface conditions are based on results of our field explorations, review of available geologic and geotechnical data, and our general experience in similar geologic settings. In general, soil conditions throughout the project site consist of surficial topsoil (forest litter) over areas of weathered and non -weathered glacial till. Isolated areas of imported fill (trail base) are also located across the site. Each major soil unit is described below, with materials interpreted as being youngest in origin and nearest to the surface described first. o Topsoil — A thin layer of topsoil or forest litter was encountered at all of the test pit locations across the project site. The topsoil consisted of a combination of silty fine sand and sandy silt with abundant organics throughout. Buried decomposed topsoil was also encountered below the trail base material in test pit TP-2. e Trail Base —Trail base material was encountered at the ground surface in test pit TP-2. This material consisted of angular gravel that appeared to be placed during initial establishment of this portion of the trail. This layer of soil was approximately 1 foot thick and possessed scattered construction debris throughout. • Weathered Glacial Till — Weathered glacial till was encountered in all test pits with the exception of TP-2. This material consisted on loose to medium dense silty sand with gravel. This material extended to depths ranging from 2 to 4 feet bgs where encountered. o Glacial Till — Glacial till was encountered in all test pit explorations across the site. The glacial till varied in consistency across the site. Evidence of cohesive (i.e fine-grained clayey) material was observed in test pits TP-1 trough TP-3; whereas coarser, less ' cohesive, glacial till was encountered in test pits TP-5 and TP-6. The glacial till IFinal Letter Report 3 HWA GeoSciences Inc. February 2, 2011 HWA Project No. 2009-058-21 Task 3 encountered in TP-4 consisted of uniform fine-grained sand. Glacial till extended below the termination depth at all test pit locations. Based on the regional geology we anticipate that very dense glacially consolidated soils extend to great depths in this area. GROUND WATER CONDITIONS Abundant ground water seepage was observed in test pits TP-1 and TP-2 at the time of our explorations. At these locations ground water seepage was observed flowing into the excavations at a rate such that 2 to 4 inches of standing water was present at the base of each excavation throughout the excavation process. The observed seepage was concentrated in the soils located just above the contact between the weathered glacial till and the glacial till. No seepage from within the unweathered denser glacial till soils was observed during our explorations. Therefore, it appears as if the ground water seepage at these locations is due to perched ground water. Additionally, based on the locations of test pits TP-1 and TP-2 in close proximity of the creels, it is assumed that this perched ground water is associated with water ingress from the creek. Conversations with King County Park personnel indicated that the creek does not fully dry up in the dry summer months, and is probably indicative of recharge from the perched water within the upper surficial materials and weathered glacial till. No ground water seepage was observed in test pits TP-3 through TP-6 at the time of our explorations. Therefore, our explorations indicate that perched ground water can be expected from the existing lift station site to some undetermined location between test pits TP-2 and TP-3. CONCLUSIONS AND RECOMMENDATIONS GENERAL The glacial till soils encountered along the proposed alignment should provide adequate support for the proposed pipe. Construction of the proposed sewer line is feasible using conventional construction equipment and standard trenching methods. However, perched ground water conditions in the vicinity of the creek crossing will require de -watering on an as needed basis. Both open -cut and trenchless construction methodologies are feasible alternatives to facilitate the required creek crossing. CREEK CROSSING As outlined previously, conversations with King County Park's representatives indicated that the creek located near the existing lift station maintains flow all year long. Therefore, construction of the proposed sewer line should account for the presence of this flow during construction of the creek crossing. However, we anticipate that the dry summer season will represent the optimum time for cronstruction of the crossing as ground water conditions will be reduced at this time. If standard open -trench construction is to be used to facilitate this creek crossing, temporary diversion of the creek's flow will be necessary to allow for pipe placement within the creek bed. Once the creek is diverted standard open -cut construction procedures, described below, should IFinal Letter Report 4 HWA GeoSciences Inc. February 2, 2011 ' HWA Project No. 2009-058-21 Task 3 be implemented. Even with diversion of the creeks flow, perched ground water should be expected during open -cut construction in this area. Therefore, de -watering will still be ' necessary. It is anticipated that this dewatering may be facilitated with approptiately positioned collector sumps and standard sump pumps. If diversion of the creek flow is not feasible or environmentally acceptable, then several trenchless pipe installation methodologies could be used to make the crossing without disturbing the creek. In consideration of the proposed sewer pipe size (15-inch diameter), we believe that a short pipe jacking or jack and bore operation would be best suited to installation of the gravity sewer line under the creek. In these operations, typically an over -sized casing is advanced by progressive jacking from the entry pit and removal of soils from the casing interior by horizontal -auger drilling equipment. We understand that casing sizes ranging from 6 to 36 inches are common for such operations. Pipe ramming is another method that is similar to jack and bore methods and consists of pneumatic hanuner advancement of the casing. Soil ' cleanout is undertaken either during advancement, to facilitate pipe penetration, or on completion, and the cleanout may be achieved by auger, air or hydraulic excavation means. In either case, the carrier pipe is inserted into the installed casing with suitable spacer provisions between the two and any void spaces are subsequently grouted. For either method, we recommend that the casing size selected be large enough to permit man -entry for purposes of removing any boulders that may obstruct casing advancement. 1 Micro -tunneling equipment and methods are available that can install underground services in glacial till soils, such installations are generally limited to pipe sizes not less than 1 foot in ' diameter, and more commonly are applied for installations considerably larger. The micro - tunneler is inserted into the entry pit and controlled remotely from the pit exterior. Stability of the cut face is controlled by compensating pressure applied to the face, if soil sloughing or running is anticipated, and soils are removed through the cutting head as the tunneler is advanced. However, we do not believe that this method would be suitable for this project due to the small pipe size and short crossing length. Moreover, the presence of boulders, such as is common in glacial till soils, in the tunnel path can be more problematic for this type of equipment. ' Horizontal directional drilling (HDD) pipe installation methods have been successfully employed on many occasions to install underground services of the size proposed herein. Normally, the entry and exit locations are selected as a function of the curvature limits of the drill stem and the pipe element to be installed. This requires that the entry and exit locations need to be setback sufficiently from the end target installation points to permit the drill stem to follow a curvilinear path that will coincide with the desired pipe profile. We do not believe that this would be a cost effective solution based on the relatively short desired length. However, if this method is to be employed, we recommend that the pipe entry point be started within the unweathered till zone. Our experience with HDD methods, where a loose material exists at surface over a dense material at depth, is that the drill head tends to deflect from the intended path and track along the surface of the denser soil. IFinal Letter Report 5 HWA GeoSciences Inc. February 2, 2011 HWA Project No. 2009-058-21 Task 3 The presence of underground obstructions, typically consisting of boulders, logs or other woody debris, or construction materials included in fills, can be problematic for all of the trenchless installation methods if they occur within the path of the advancing casing pipe, and could also pose problems for advancement of sheet piles that might be considered for pit shoring purposes. Obstructions are particularly problematic for small diameter casings that are not large enough to permit man -entry to clear the obstruction. The nature of glacial till is such that large boulders could be encountered within the path. Because a large boulder was encountered in TP-3, we recommend that contractual language be included in the project bid documents to indicate their possible presence to contractors, such that the potential associated construction risks may be included in the contract bid prices. Each of these trenchless construction applications, with the exception of directional drilling, requires the construction of significant jacking and receiving pits. These pits are generally temporarily shored excavations constructed large enough to accept the associated equipment at the desired grade. For purposes of this project, these pits would most likely be constructed as close to each side of the creek as possible (minimizing the distance of trenchless installation). Given the proximity to the creek, and the perched ground water encountered in this area, each pit would require de -watering to maintain a dry working area. The shoring normally associated with jacking and receiving pits generally consist of internally braced sheet piles, soldier piles and lagging, or trench boxes. If jacking and receiving pits are required, shoring should be designed by the contractor and constructed to support lateral loads exerted by the soil mass. In addition, any surcharge from construction equipment, construction materials, or excavated soils should be included in the shoring design. Figure 3 presents recommended earth pressures for temporary shoring. It should be noted that the earth pressure diagram does not account for hydrostatic pressure associated with the perched ground water. The magnitude of the hydrostatic pressure will, however, depend on the type of shoring system used (e.g. water pressures would be higher on sheet piling than on lagged shoring systems, or trench boxes). Therefore, we recommend that the contractor account for hydrostatic pressure during design based on the type of shoring utilized. Furthermore, we recommend that the contractor be required to submit a shoring/excavation plan designed by a professional engineeer for review and approval prior to construction. The plan should be required to contain specific measures for temporary support and protection of all existing utilities and structures that may be located within such proximity of the work as to be potentially affected. OPEN -CUT TRENCH CONSTRUCTION Open -cut excavations for the sewer line can be accomplished with conventional excavating equipment such as backhoes and trackhoes. Because of the dense to very dense nature of the glacial till soils, hard digging can be expected along the project alignment. The contractor should account for this in his bid price and no subsequent claims for hard digging or "rock" excavation should be allowed, including the possible presence of large boulders. Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. In accordance with Part N of Washington Administrative Code Final Letter Report 6 HWA GeoSciences Inc. February 2, 2011 HWA Project No. 2009-058-21 Task 3 (WAC) 296-155, latest revisions, all temporary cuts in excess of 4 feet in height must be either sloped or shored prior to entry by personnel. The existing native soils generally consist of loose to medium dense sands and silty sands with gravel (weathered glacial till) underlain by dense to very dense silty sand with gravel (unweathered glacial til). The near surface weathered glacial till generally classify as Type C soil, per WAC 296-155, and, if no trench box is used, should be sloped no steeper than 1'/2H:IV. The underlying dense to very dense glacial till generally classify as Type A soil, per WAC 296-155, and, if no trench box is used, should be sloped no steeper than 3/4H:1 V. Flatter side slopes will be required where groundwater seepage occurs. Lateral support for the trench walls should be provided by the contractor to generally prevent loss of ground. General recommendations for design and implementation of shoring and bracing systems are presented below. Trench boxes should provide suitable support for trench excavations in native glacial till soils provided settlement sensitive structures or utilities are not situated near the excavation. Precautions should be taken during removal of the shoring to minimize disturbance of the placed pipe, underlying bedding materials, and native subgrade soils. ® The contractor should be responsible for control of ground and surface water and should employ sloping, slope protection, ditching, sumps, dewatering, and other measures as necessary to prevent sloughing of soils. Although not anticipated, if unsuitable soils are encountered at the pipe invert during excavation, they should be over -excavated and removed. Unsuitable soils include soft peat, silt or organic material (i.e. logs, stumps etc.). Over -excavated areas should be backfilled with I1/4-inch minus crushed rock meeting the gradation requirements for crushed surfacing, as described in Section 9-03.9(3) of the WSDOT Standard Specifications (WSDOT, 2010). Over -excavation to remove unsuitable soils from below the pipeline should be limited to a depth of 3 feet. It should extend for the full depth on both sides of the pipe a distance which is equal to the depth of the over -excavation, or one pipe diameter, whichever is less. Where the native soils are competent and do not require over -excavation, bedding material should be placed directly on the undisturbed native soils. Trench bottoms should be free of debris and standing water. If native subgrade soils are disturbed, the disturbed material should be removed and replaced with additional compacted bedding material. Pipe bedding material, placement, compaction, and shaping should be in accordance with the project specifications and the pipe manufacturer's recommendations. In general, the pipe bedding should meet the gradation requirements of Section 9 03.12(3) Gravel Backfill for Pipe Zone Bedding, of the 2010 WSDOT Standard Specifications. Pipe bedding should provide a firm uniform cradle for support of the pipe. A minimum 4-inch thickness of bedding material beneath the pipe should be provided. Prior to installation of the pipe, the pipe bedding should be shaped to fit the lower part of the pipe exterior with reasonable closeness to provide uniform support along the pipe. Pipe bedding material should also be used as pipe zone backfill and placed in layers and tamped around the pipes to obtain complete Final Letter Report 7 HWA GeoSciences Inc. February 2, 2011 HWA Project No. 2009-058-21 Task 3 contact. To protect the pipe, bedding material should extend at least 6 inches above the top of the pipe. The native glacial till soils are fine grained in nature and are likely to be very sensitive to moisture variation, which could have a very adverse effect on their ability to be reused as trench backfill material. In general, however, the moisture content of the unweathered till is anticipated to be within reasonable limits of the optimum values that would be suitable for compaction to required density levels for trench backfill. Accordingly, we believe that with selective use of lower moisture content materials, the native glacial till may be reused for backfill in areas which will not be developed and require higher quality subgrade conditions for future facilities (e.g. roadways, sidewalks, parking areas, etc.). We recommend that all bolders and any cobbles larger than 4 inches be removed from the trench backfill, when native soils are being reused. Where such future development may overlie the sewer line, the native materials should not be re -used as trench backfill. Imported trench backfill should be used in these areas and should meet the gradation requirements of Gravel Borrow as specified in Section 9-03.14(1), of the 2010 WSDOT Standard Specifications. The backfill should be compacted in a systematic manner to at least 92 percent of the maximum dry density (MDD), as determined by ASTM test method D1557. Beneath areas anticipated to experience future vehicle traffic, the upper 4 feet of trench backfill should be compacted to 95% of MDD. In landscaped areas backfill should be compacted to at least 90 percent of MDD, except the top 2 feet, which should be compacted to at least 92 percent. During placement of the initial lifts, the trench backfill material should not be dropped directly on the pipe. Heavy vibratory equipment should not be permitted to operate directly over the pipe until a minimum of 3 feet of backfill has been placed over the pipe bedding. If the trench backfill is placed at the compaction levels indicated above, settlement of the trench backfill is expected to be about 1 % of the thickness of the backfill. DEWATERING Based on the perched ground water encountered in test pits TP-1 and TP-2 we anticipate that the contractor will have to conduct some form of de -watering during trench excavation, and potential pit excavations, located between the existing lift station and some point north of test pit TP-3. Based on the perched ground water and the relatively impermeable nature of the glacial till we anticipate that this de -watering effort will consist of strategically positioned sump pits and not wells. However, design of the de -watering system should be the responsibility of the contractor. WET WEATHER EARTHWORK ' We recommend that the work be performed during the dry summer season, when excavation and handling of the moisture sensitive native soils will be most readily performed, However, if necessary, general recommendations relative to earthwork performed in wet weather or in wet conditions are presented below. These recommendations should be incorporated into the contract specifications. Final Letter Report 8 HWA GeoSciences Inc. February 2, 2011 ' HWA Project No. 2009-058-21 Task 3 ' Earthwork should be performed in small areas to minimize exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly by the placement ' and compaction of clean structural fill. The size and type of construction equipment used may need to be limited to prevent soil disturbance. ' m The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water. o The ground surface within the construction area should be sealed by a smooth drum roller, or ' equivalent, and under no circumstances should soil be left uncompacted and exposed to moisture infiltration. ' 0 Excavation and placement of fill material should be undertaken under the observation of a representative of the geotechnical engineer, to determine that the work is being accomplished in accordance with the project specifications and the recommendations contained herein. ' CONDITIONS AND LIMITATIONS 1 We have prepared this assessment for Carollo Engineers and the City of Renton for use in design of this project. The conclusions and interpretations presented in this report are based upon review of existing information and field data recently acquired at specific locations along the 1 proposed project alignment, and should not be construed as our warranty of existing subsurface conditions along all portions of the project. Experience has shown that soil and ground water conditions can vary significantly over small distances. Inconsistent conditions can occur ' between exploration locations and may not be detected by a geotechnical study of this nature. If, during future site operations, subsurface conditions are encountered which vary appreciably from ' those described herein, HWA should be notified for review of the recommendations of this report, and revision of such if necessary. Our work scope did not include environmental assessments or evaluations regarding the presence 1 or absence of wetlands or hazardous substances in the soil, surface water, or ground water at this site, except to the extent that is discussed in this report in respect to geotechnical considerations for this project. I Final Letter Report 9 HWA GeoSciences Inc. February 2, 2011 HWA Project No. 2009-058-21 Task 3 We appreciate the opportunity to provide geotechnical services on this project. Sincerely, HWA GEOSCIENCES INC. O J• HV Z A 4'�JC►► RFGIs►���,�` Donald J. Huling, P.E. Geotechnical Engineer Attachments: Lorne A. Balanko, P.E. Principal Geotechnical Engineer Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Figure 3 Design Earth Pressures for Temporary Braced Shoring Appendix A: Field Exploration Figure A-1 Legend of Terms and Symbols Used on Exploration Logs Figures A-2 to A-7 Logs of Test Pits TP-1 through TP-12 Appendix B: Laboratory Testing Figures 13-1 to B-2 Grain Size Distribution Test Results REFERENCES Booth Derek P, and Wisher Aaron P, 2006, Geologic Map of King County, Washington. Washington Department of Transportation (WSDOT), 2010, Standard Specifications for Road, Bridge, and Municipal Construction, M 41-10. Final Letter Report 10 HWA GeoSciences Inc. R mt- I PROPOSED SEWER LINE ' €' x �4'S ;C :`:v, '� 1* t �a y{. TL�S� :Y• :+` `'yt-.s��'. � �yS aY 5 � '% ,, �}s''h 'C 4. .+� `�C � C C.: L TP_4 `y` TP-2 .F� TP 1 OHL , .x. - �_ Y, •r.. TP-3 /..-I' _i A 1. \ 1 .p� /�• • I / T i p O s i i, (-fl �.e Q V, O TP_6 Imo/ /I 12 ' i ■ a ■. t r ���C- 5T' �' 'f `'C;' V oil ■ _ - a 'r' II '.e'_ �{ si � ,4�'+• it � A 'Mr ) .xr 0' 40' 80' 160' I LEGEND PROPOSED SEWER LINE TP-1 EAST RENTON LIFT STATION ELIMINATIONSITE AND 1�- TEST PIT DESIGNATION AND APPROXIMATE LOCATION ' HWAGEOSCIENCES INC. RENTON, WASHINGTON EXPLORATION FIGURE NO. DRAWN BY EFK CHECK BY DH P0.0ffR N0, DATE 01.03.10 2009-058-21 PM 30H+30D II 621D ACTIVE PRESSURE PASSIVE PRESSURE Influence Factor ( i ) for Surcharge Loads For: x>:H 0=0 H>x>H/2 i=0.5 H/2>x>H/4 1=0.75 H/4 > I N ®TES: x - 1. ASSUMED SOIL CONDITIONS: GROUND SURFACE TO 4 FT: (b = 35°, y = 135PCF, K a = 0.27 4 TO (H+D). FT: (b = 401, y = 135PCF, K a = 0.22, K p = 4.60 2. SURCHARGE LOADS SHOULD BE ADDED WHERE APPROPRIATE, USING THE FORMULA ABOVE. 3. SHORING EMBEDMENT (D) SHOULD BE DETERMINED BY SUMMATION OF MOMENTS ABOUT THE LOWEST BRACE. 4. NO FACTOR OF SAFETY HAS BEEN APPLIED TO THE RECOMMENDED PASSIVE EARTH PRESSURE. (FS=1.5 MINIMUM RECOMMENDED) 5. DISTANCES ARE IN UNITS OF FEET; PRESSURES ARE IN UNITS OF POUNDS PER SQUARE FOOT. =A I � HMGE0SG7ENCES INC EAST RENTON LIFT STATION ELIMINATION RENTON, WASHINGTON 3-058 ER.DWG < IG 3> Plotted: 1/26/2011 7:12 PM NOT TO SCALE FIGURE NO. DRAWN BY EFK 3 CHECK BY DH PROJECT NO. DATE 01.05.11 2009-058-21 s �_ 1 4 �� 11 ! R '0• �� 2V RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE COHESIONLESS SOILS COHESIVE SOILS Approximate Approximate Density N (blows/ft) Relative Density(%) Consistency N (blows/ft) Undrained Shear Strength (psf) Very Loose 0 to 4 0 - 15 Very Soft 0 to 2 <250 Loose 4 to 10 15 - 35 Soft 2 to 4 250 - 500 Medium Dense 10 to 30 35 - 65 Medium Stiff 4 to 8 500 - 1000 Dense 30 to 50 65 - 85 Stiff 8 to 15 1000 - 2000 Very Dense over 50 85 - 100 Very Stiff 15 to 30 2000 - 4000 Hard over 30 >4000 USCS SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP DESCRIPTIONS Gravel and GW Well -graded GRAVEL Coarse Clean Gravel e ` Grained Gravelly Soils (little or no fines) o Q= GP Poorly -graded GRAVEL Soils More than 50% of Coarse Gravel with o GM Silly GRAVEL Fraction Retained Fines (appreciable on No. 4 Sieve amount of fines) GC Clayey GRAVEL Sand and Clean Sand SW Well -graded SAND More than Sandy Soils (little or no fines) SP Poorly -graded SAND 50% Retained 50% or More on No. of Coarse Sand with SM Silty SAND 200 Sieve Fines (appreciable Fraction Passing Size amount of fines) SC Clayey SAND No. 4 Sieve ML SILT Fine Silt CL Lean CLAY Grained and Liquid Limit Soils Less than 50% Clay _ - OL Organic SILT/Organic CLAY MH Elastic SILT 50% or More Silt Liquid Limit Passing and or More CH Fat CLAY No. 200 Sieve Clay50% Size OH Organic SILT/Organic CLAY Highly Organic Soils PT PEAT COMPONENT DEFINITIONS COMPONENT SIZE RANGE Boulders Larger than 12 in Cobbles 3 in to 12 in Gravel 3 in to No 4 (4.5mm) Coarse gravel 3 in to 314 in Fine gravel 3/4 in to No 4 (4.5mm) Sand No. 4 (4.5 mm) to No. 200 (0,074 mm) Coarse sand No. 4 (4.5 mm) to No. 10 (2.0 mm) Medium sand No. 10 (2.0 mm) to No. 40 (0.42 mm) Fine sand No. 40 (0.42 mm) to No. 200 (0.074 mm) Silt and Clay Smaller than No. 200 (0.074mm) TEST SYMBOLS %F Percent Fines AL Atterberg Limits: PL = Plastic Limit LL = Liquid Limit CBR California Bearing Ratio CN Consolidation DO Dry Density (pcf) DS Direct Shear GS Grain Size Distribution K Permeability MD Moisture/Density Relationship (Proctor) MR Resilient Modulus PID Photoionization Device Reading PP Pocket Penetrometer Approx. Compressive Strength (tsf) SG Specific Gravity TC Triaxial Compression TV Torvane Approx. Shear Strength (tsf) UC Unconfined Compression SAMPLE TYPE SYMBOLS ® 2.0" OD Split Spoon (SPT) (140 lb. hammer with 30 in. drop) IShelby Tube 3-1/4" OD Split Spoon with Brass Rings OSmall Bag Sample ® Large Bag (Bulk) Sample ® Core Run Non-standard Penetration Test (3.0" OD split spoon) GROUNDWATER SYMBOLS Q Groundwater Level (measured at time of drilling) Groundwater Level (measured in well or open hole after water level stabilized) COMPONENT PROPORTIONS PROPORTION RANGE DESCRIPTIVE TERMS < 5% Clean 5 - 12% Slightly (Clayey, Silty, Sandy) 12 - 30% Clayey, Silty, Sandy, Gravelly 30-50% Very (Clayey, Silty, Sandy, Gravelly) Components are arranged in order of increasing quantities. NOTES: Soil classifications presented on exploration logs are based on visual and laboratory observation. Soil descriptions are presented in the following general order: MOISTURE CONTENT Density/consistency, color, modifier (if any) GROUP NAME, additions to group name (if any), moisture DRY Absence of moisture, dusty, content. Proportion, gradation, and angularity of constituents, additional comments. dry to the touch. (GEOLOGIC INTERPRETATION) MOIST Damp but no visible water. Please refer to the discussion in the report text as well as the exploration logs for a more WET Visible free water, usually complete description of subsurface conditions. soil is below water table. LEGEND OF TERMS AND East Renton Lift Sation Elimination SYMBOLS USED ON 1 I-M11GEOSIMNCESINC Renton, Washington EXPLORATION LOGS PROJECT NO.: 2009-058-21 FIGURE: A-1 LEGEND 2009-058-21.GPJ 2/2/11 EXCAVATION COMPANY: Glenbrook Services LOCATION: See Figure 2 EXCAVATING EQUIPMENT: Kubota KX-121 DATE COMPLETED: 12/2/10 SURFACE ELEVATION: 394 * Feet LOGGED BY: D. Huling C6 U) g _ UI J w J O m rn 0 cq D DESCRIPTION 0 '--" Medium dense, silty SAND with gravel, moist, abundant rootlets and organics observed throughout. GM Medium dense to dense, yellowish brown, silty, very sandy, GRAVEL, ° moist changing to wet at 3 feet. [WEATHERED GLACIAL TILL] 3 ° Note: 400 Pair abandoned Quest phone line encountered _at_3.5 feet. GM Very dense, olive brown, silty, very sandy, GRAVEL, moist. [GLACIAL TILL Test pit was terminated in very dense glacial till at a depth of 4.5 feet. 6 Further exploration was not completed due to encountered utility line. Abundant ground water seepage observed between 3 and 4 feet below ground surface. te= 1 12- w W m EL o U) Elf Lu a Z X �- uJ z a a F— 00 w =) Of ) vai v 2 O O O 0 0 S-1 23 GS Q 15 NOTE: For a proper understanding of the nature of subsurface conditions, this exploration log should be read in conjunction with the text of the geotechnical report. This log of subsurface conditions applies only at the specified location and on the date indicated and therefore may not necessarily be indicative of other times and/or locations. SKETCH OF SIDE OF PIT HORIZONTAL DISTANCE (feet) 3 6 9 12 r-- 0 1 -3 1 -6 1 -9 1 sew -15 1 LOG OF TEST PIT East Renton Lift Sation Elimination TP-1 HWAGEMENCES INC Renton, Washington PAGE: 1 of 1 PROJECT NO.: 2009-058-21 FIGURE: A-2 TP15 2009-058-21.GPJ 2/2/11 EXCAVATION COMPANY: Glenbrook Services EXCAVATING EQUIPMENT: Kubota KX-121 SURFACE ELEVATION: 392 t Feet LOCATION: See Figure 2 DATE COMPLETED: 12/1/10 LOGGED BY: D. Huling Uj U g w W m co of w U a D ~ Lu Q m 0 w W w Z SKETCH OF SIDE OF PIT a 0 2 0 g 2 z = 0 HORIZONTAL DISTANCE (feet) a 0 (n D DESCRIPTION ai U) � LU ~O ((.0 0 3 6 9 12 15 0 0 - pppp � , 0 .. ... ... ... ... .. .... ... 3 O S-1 16 GS `' t ` 3 .. . ... a S-2 16 GS ..... ... .............. ... ... ... 0 :^ :tea .. 6 .... ......... ... ... ........... ... ©�:.a.. 9 y: 9 Test pit terminated at 9.5 feet below ground surface (bgs) in dense ......:............. ......... ....:..... . ......:.......:...... ......:......:...... ......:.. glacial till. Ground water seepage observed between 1.5 and 3.5 feet bgs. 12 12 15 15 NOTE: For a proper understanding of the nature of subsurface conditions, this exploration log should be read in conjunction with the text of the geotechnical report. This log of subsurface conditions applies only at the specified location and on the date indicated and therefore may not necessarily be indicative of other times and/or locations. GM Loose, brown, silty, sandy GRAVEL, moist, with scattered ° construction debris. [FRAIL BASE] Soft, dark brown, sandy, SILT with gravel, moist, abundant organics throughout. SM [BURIED FOREST LITTER] Groundwater seepage and caving observed between 1.5 and 3.5 feet bgs. Dense to very dense, yellowish brown, silty, gravelly, SAND, moist, cementation observed throughout. [GLACIAL TILL] Grades gray with more sand at 7 feet. LOG OF TEST PIT A ® East Renton Lift Sation Elimination TP-2 HWAGEOSaENCES INC Renton, Washington PAGE: 1 of 1 PROJECT NO.: 2009-058-21 FIGURE: A-3 TP15 2009-058-21.GPJ 2/2/11 EXCAVATION COMPANY: Glenbrook Services LOCATION: See Figure 2 EXCAVATING EQUIPMENT: Kubota KX-121 DATE COMPLETED: 12/1/10 SURFACE ELEVATION: 390 f Feet LOGGED BY: D. Huling rn g U J O U m cn w U) 0 W D 0 me 6— =-*Z 1 12— DESCRIPTION Loose, dark brown, silty, SAND with scattered gravel, moist, abundant organics encountered throughout. [FOREST LITTER] SM Medium dense, reddish brown, silty, very gravelly, SAND, moist. [WEATHERED GLACIAL TILL] Desne to very dense, olive brown, silty, very gravelly, SAND, moist. SM [GLACIAL TILL] Note: 12 inch diamter boulder encountered at 7 feet. Test pit terminated at 10 feet below ground surrace (bgs) in very dense glacial till. No ground water observed in the test pit at the time of exploration. w W m D a a z W W W F- M Z to (0 ~ Z a a F- w D W Q Q U U 00 20 O 0 0 S-1 13 GS S-2 10 15J NOTE: For a proper understanding of the nature of subsurface conditions, this exploration log should be read in conjunction with the text of the geotechnical report. This log of subsurface conditions applies only at the specified location and on the date indicated and therefore may not necessarily be indicative of other times and/or locations. SKETCH OF SIDE OF PIT HORIZONTAL DISTANCE (feet) 3 6 9 12 ai a 15 0 r— 0 -3 -6 -9 -12 1 sN10 LOG OF TEST PIT ' East Renton Lift Sation Elimination TP-3 HMGEOSCIENCES INC Renton, Washington PAGE: 1 of 1 PROJECT NO.: 2009-058-21 FIGURE: A-4 TP15 2009-058-21.GPJ 2/2/11 EXCAVATION COMPANY: Glenbrook Services LOCATION: See Figure 2 EXCAVATING EQUIPMENT: Kubota KX-121 DATE COMPLETED: 12/1I10 SURFACE ELEVATION: 382 t Feet LOGGED BY: D. Huling E DESCRIPTION SM A Loose, brown, silty, SAND, moist. [FOREST LITTER] Medium dense, reddish brown, silty, very gravelly, SAND, moist. [WEATHERED GLACIAL TILL] Dense, olive brown, silty, fine SAND, moist, no cohesion observed. SM [GLACIAL TILL] w m }a o U) CO Ofw w F Z W W wF— M Z w ~ of Z a a ai z 2000 = 0 W U) 0 0 OS-1 10 GS 9 Test pit terminated at 10 feet in dense fine grain sandy glacial till. No ground water seepage observed at the time of excavation. 12 15 NOTE: For a proper understanding of the nature of subsurface conditions, this exploration log should be read in conjunction with the text of the geotechnical report. This log of subsurface conditions applies only at the specified location and on the date indicated and therefore may not necessarily be indicative of other times and/or locations. SKETCH OF SIDE OF PIT HORIZONTAL DISTANCE (feet) 3 6 9 12 -3 1 -6 1 -9 1 -12 1 -15 1 LOG OF TEST PIT East Renton Lift Sation Elimination TP-4 HWAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 1 PROJECT NO.: 2009-058-21 FIGURE: A-5 TP15 2009-058-21.GPJ 212111 EXCAVATION COMPANY: Glenbrook Services LOCATION: See Figure 2 EXCAVATING EQUIPMENT: Kubota KX-121 DATE COMPLETED: 12/1/10 SURFACE ELEVATION: 381 t Feet LOGGED BY: D. Huling 3- t. 9- MPA DESCRIPTION SM Loose, brown, silty, SAND, moist. [FOREST LITTER] Medium dense, reddish brown, silty, very gravely, SAND, moist. [WEATHERED GLACIAL TILL] _ _ _ _ _ _ _ SM Dense increasing to very dense with depth, olive brown, silty, gravelly, SAND, moist, no cohesion observed throughout. [GLACIAL TILL] Note: coarse sand and gravel content increases at 6 feet below ground surface. Test pit terminated at 9.5 feet in dense glacial till. No ground water seepage observed at the time of excavation. w W m a_ o F- LU !- Z W F of uJ LLJ F ❑ Z a a U 00 w H 0 � ai v¢i 2 U O 0 0 15J NOTE: For a proper understanding of the nature of subsurface conditions, this exploration log should be read in conjunction with the text of the geotechnical report. This log of subsurface conditions applies only at the specified location and on the date indicated and therefore may not necessarily be indicative of other times and/or locations. SKETCH OF SIDE OF PIT HORIZONTAL DISTANCE (feet) 3 6 9 12 H IL 15 0 r— 0 1 -3 1 S� -12 1 -15 1 LOG OF TEST PIT gon East Renton Lift Sation Elimination TP-5 HWAGEOR'WirALNCES INC. Renton, Washington PAGE: 1 of , PROJECT NO.: 2009-058-21 FIGURE: A-6 TP15 2009-058-21.GPJ 2/2/11 EXCAVATION COMPANY: Glenbrook Services LOCATION: See Figure 2 EXCAVATING EQUIPMENT: Kubota KX-121 DATE COMPLETED: 12/1/10 SURFACE ELEVATION: 376 * Feet LOGGED BY: D. Huling W m Lu w J F Z W I— = J m O (n W J as W J 0- Z F W H 0 Z ~ co z = O O 0 o vri � DESCRIPTION W 20 0 3 3-1 6 —1 9--� 12 `. SM Loose, brown, silty, SAND, moist. [FOREST LITTER] Medium dense, reddish brown, silty, very gravelly. SAND, moist. [WEATHERED GLACIAL TILL] Very dense, olive brown, silty, very gravelly, SAND, moist. SM [GLACIAL TILL] Test pit terminated at 9.5 feet in dense glacial till. NO ground water seepage observed at the time of excavation. 15J NOTE: For a proper understanding of the nature of subsurface conditions, this exploration log should be read in conjunction with the text of the geotechnical report. This log of subsurface conditions applies only at the specified location and on the date indicated and therefore may not necessarily be indicative of other times and/or locations. SKETCH OF SIDE OF PIT HORIZONTAL DISTANCE (feet) 6 9 12 2 o_ Lu 15 0 r0 1 -3 VIIIIIIIIII -9 -12 1 -15 1 LOG OF TEST PIT East Renton Lift Sation Elimination TP-6 HMGEORALNCES INC. Renton, Washington PAGE: 1 of PROJECT NO.: 2009-058-21 FIGURE: A-7 TP15 2009-058-21.GPJ 212/11 LABORATORY TESTING GRAVEL SAND SILT C L7A 7YU.S. STANDARD SIEVE SIZES 3/4" 3" 1-1/2" 5/8" 3/8" #4 #10 #20 #40 #60 #100 #200 100 I I I I I I I I I I I I I I I I I I I 90 I I I I I I I I I I I I I I I I $0 H I I I I I I I I = I I I I I I I I I 70 Ll1 I I I I I I I I I I I I 1 I I I I m 60 W 50 I I I I I Z I I I I LL I I I I I I I I I I— 40 Z I I I I I I I I I W I U I I I I I I I 30 W d I I I I I I I I I 20 I I I I I I I I I I I I I I I I I I I 10 I I I I I I I I I I I 0 I L �i� 50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005 GRAIN SIZE IN MILLIMETERS Coarse Fine Coarse Medium Fine SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name % MC LL PL pl Gravel Sand Fines ® TP-1 S-1 2.5 - 3.0 (GM) Dark yellowish brown, silty GRAVEL with sand 23 39.6 37.7 22.6 ® TP-2 S-1 3.0 - 4.0 (SM) Olive brown, silty SAND with gravel 16 36.4 45.6 18.0 0 TP-2 S-2 5.0 - 6.0 (SM) Olive brown, silty SAND with gravel 16 32.0 51.2 16.8 PARTICLE -SIZE ANALYSIS Renton Lift Station Elimination OF SOILS HMGEOsaENCES INC. Renton, Washington METHOD ASTM D422 PROJECT NO.: 2009-058-21 FIGURE: B-� HWAGRSZ 2009058.GPJ 2/2/11 U.S. STANDARD SIEVE SIZES 3/4" 3" 1-1/2" 5/8' 3/8" #4 #10 #20 #40 #60 #100 #200 100 II I I i t I I I I I I I I I I 90 I I I I I I I I I I I I I I 1 I $0 E— I I I I I I I I I = I I I I I I I I I I 70 W I I I I I I I I I I 1 1 I I I I I I 60 I I 0}p I I I I I I I I I I I I I I I I I L11 50 I I I I I I Z I I I I I I I I I I f— 40 z W I I I I I I I q I I U I I I I I I I I I � 30 I I I I I I I I I � I I I I I I I 1 I I 20 I I I I I I I I I I I I I I I I I I I 10 I I I I I I I I I I I I I I I I I I I I 0 50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005 GRAIN SIZE IN MILLIMETERS GRAVEL SAND SILT CLAY Coarse Fine Coarse Medium Fine SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name % MC LL PL PI Gravel Sand Fines ® TIP-3 S-1 2.0 - 3.0 (SM) Dark yellowish brown, silty SAND with gravel 13 37.5 45.3 17.1 ® TP-3 S-2 3.0 - 4.0 (SM) Olive brown, silty SAND with gravel 10 30.4 52.9 16.7 A TP-4 S-1 3.0 - 4.0 (SM) Olive brown, silty SAND 10 0.0 83.0 17.0 PARTICLE -SIZE ANALYSIS e East Renton Lift Station Elimination OF SOILS HMIGEOSCIENCES INC. Renton, Washington METHOD ASTM D422 PROJECT NO.: 2009-058-21 FIGURE: B-2 HWAGRSZ 2009058.GPJ 2/2/11