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LUA-06-102_Misc
Ai''·· ~ -,--, ~,, JUN 1 2 2006 .,:,·3i~,'...LC ",'.1 At Shannon & ~Vi/son, uirr 1111ssion is to be n progres.1·il'e, ,vell- inanaged pn?fessiml(I/ rnnsulting firm in the fields of engineering and applif'li earlh scil'n(·e.1. 011r goal i.1 to perfr,rm our W:'Tvice.1 with rhe highest degree o{f!ro/e.1sionalism with Jue considemtion to !he best inlerc.11.1 o/ !hr ;mblic, our clients, und our empfoye1:.':,. Geotechnical Report Central Plateau Interceptor Renton, Washington June 9, 2006 Submitted To: Roth Hill En~ineering Partners, LLC 2600 1161 Avenue NE, Suite 100 Bellevue, Washington 98004 By: Shannon & Wilson, Inc. 400 N 34 1 " Street, Suite 100 Seattle, Washington 98103 21-1-20442-001 SHANNON &WILSON, INC. TABLE OF CONTENTS Page 1.0 INTRODUCTION ................................................................................................................. 1 1.1 Scope of Services ....................................................................................................... 1 1.2 Limitations ................................................................................................................. 2 2.0 SITE AND PROJECT DESCRIPTION ................................................................................. 3 2.1 Site Description .......................................................................................................... 3 2.2 Project Description .................................................................................................... .4 3.0 SUBSURFACE CONDITIONS ............................................................................................. 5 3.1 General Geology ........................................................................................................ 5 3.2 Subsurface Conditions ............................................................................................... 6 3.3 Hydrogeology ............................................................................................................. 8 4.0 SLOPE ST ABILITY ............................................................................................................ 1 O 4.1 Slope Stability Observations .................................................................................... 1 O 4.2 Slope Stability Analyses .......................................................................................... 11 5.0 CONSTRUCTION METHOD ALTERNATIVES .............................................................. 11 5.1 Trenchless Methods ................................................................................................. 12 5.1.1 Horizontal Directional Drilling (HDD) ..................................................... 12 5.1.2 Auger Boring ............................................................................................. 13 5.2 Trenching Methods .................................................................................................. 13 6.0 ENGINEERING CONSIDERATIONS AND RECOMMENDATIONS ............................ 13 6.1 Horizontal Directional Drilling (HDD) .................................................................... 14 6.1.1 Soil Behavior Along Bore Path ................................................................. 14 6.1.2 Pipe Friction During Pull-back .................................................................. 15 6.1.3 Hydraulic Fracturing .................................................................................. 16 6.2 Auger Boring ............................................................................................................ 17 6.3 Surface-mounted High-density Polyethylene (HOPE) Pipe .................................... 18 6.4 Trenching ................................................................................................................. 19 6.4.1 Surface Water and Groundwater Control .................................................. 20 6.4.2 Pipe Bedding and Initial Backfill .............................................................. 20 6.4.3 Subsequent Backfill and Compaction ........................................................ 21 6.5 Wet Weather Conditions .......................................................................................... 21 6.6 Erosion Control ........................................................................................................ 22 7.0 CONSTRUCTION CONSIDERATIONS ........................................................................... 23 21-1-20442-00 l-Rl-Rev.doc/wp/LKD 21-1-20442-001 TABLE OF CONTENTS (cont.) SHANNON &WILSON, INC. 7.1.1 7.1.2 7.1.3 7.1.4 7.1.5 7.1.6 7.1.7 7.1.8 7.1.9 7.1.10 7.1.11 7.1.12 7.1.13 7.1.14 Page Staging Areas ............................................................................................. 25 Fixed Entry and Exit Points ....................................................................... 26 Corridor Width ........................................................................................... 26 Corridor Depth ........................................................................................... 26 Tolerances ... , .............................................................................................. 27 Tracking System ........................................................................................ 27 Disposal of Spoils ...................................................................................... 27 Pipe Characteristics ................................................................................... 28 Connections ............................................................................................... 29 Obstructions ............................................................................................... 29 Buried Utilities ........................................................................................... 29 Settlements ................................................................................................. 30 Contractor Qualifications ........................................................................... 30 Construction Submittal .............................................................................. 31 8.0 DOCUMENT REVIEW AND CONSTRUCTION OBSERVATIONS .............................. 31 9.0 REFERENCES ..................................................................................................................... 32 LIST OF FIGURES Figure No. 1 Vicinity Map 2 Site and Exploration Plan 3 Generalized Subsurface Profile A-A' 4 Generalized Subsurface Profile B-B' 5 Generalized Subsurface Profile C-C' 6 Typical Pipeline Anchoring Details (2 sheets) 7 Typical Pipe Trench Section Excavating in Dry LIST OF APPENDICES Appendix A Subsurface Explorations B Geotechnical Laboratory Testing C Groundwater Analytical Laboratory Results D Results of Slope Stability Analyses E Important Information About Your Geotechnical Report 21-1-20442-001-Rl -Rev.doc/wp/LKD 21-1-20442-001 II , SHANNON &WILSON, INC. GEO TECHNICAL REPORT CENTRAL PLATEAU INTERCEPTOR RENTON, WASHINGTON 1.0 INTRODUCTION This report presents the results of our field explorations, laboratory testing, and geotechnical engineering studies for proposed construction of two sanitary sewer mains down steep slopes in the City of Renton, Washington (City). The two sewer mains would serve the residential area of Maplewood Heights, located along the southern edge of the upland plateau north of the Cedar River Valley. Construction method alternatives currently envisioned for the steep slope portions of the project consist of horizontal directional drilling (HDD), auger boring, and surface- mounted pipe. Shannon & Wilson previously conducted a feasibility study of construction alternatives and prepared a preliminary geotechnical report titled, "Central Plateau Interceptor Alternatives," dated June 16, 2005. After the completion of that study, the City decided to construct the steep slope portions of the two sewer mains using HDD and proposed a single alignment for the steep slope east of 154th Place SE and two alternative alignments for the steep slope west of 154'h Place SE. Proposed construction methods and alignments have been modified during the course of our current studies. 1.1 Scope of Services Four our previous studies, we reviewed stereo-pair aerial photographs and reviewed the logs of a few borings located in the vicinity of the project. To further evaluate design and construction issues, our scope of services for the current study included the following main elements: ,.. Drilling, sampling and logging of three borings: one east 154th Place SE and two west of l 54'h Place SE, to evaluate subsurface materials and conditions likely to be encountered during HDD or auger boring construction. ,.. Excavation of two test pits, one each at the bases of the west and east slopes, to evaluate shallow subsurface conditions near proposed HDD exit or entry pits. 21-1-20442-001-RI -Rev .doclwp/LKD 21-1-20442-001 1 SHANNON &WILSON, INC. ~ Drilling of four shallow probes using hand-operated equipment on the slope west of 1541hPlace SE to evaluate shallow subsurface conditions for surface-mounted pipe on the west slope. ~ Installation of a monitoring well in the cast boring, and a monitoring well and vibrating wire piezometer (VWP) in the deep west boring to evaluate groundwater conditions that may affect or be impacted by HDD or other activities. ~ Sampling and chemical analysis of groundwater from the well installed in the deep west boring to evaluate potential adverse impacts to the aquifer from HDD construction. ~ Limited geotechnical testing of soil samples collected from the borings and test pits. ~ Stability analyses of the steep west slope in the vicinity of the proposed surface-mounted pipe. ~ Evaluation of the results of the subsurface investigation and soil and groundwater laboratory analyses, and preparation of this report. Our work on this project was authorized by a contract between Shannon & Wilson, Inc. and Roth Hill Engineering Partners, LLC, dated May 5, 2005, and was conducted in general accordance with our scope of work dated October 3, 2005. 1.2 Limitations Within the limitations of the scope, schedule, and budget, the analyses, conclusions, and recommendations presented in this report were prepared in accordance with generally accepted professional geotechnical engineering principles and practices at the time this report was prepared. We make no other warranty, either express or implied. The analyses, conclusions, and recommendations contained in this report are based on our understanding of the project as described herein and site conditions as they presently exist. For the purpose of presenting design recommendations, we assumed that the results of the explorations are representative of the subsurface conditions along the proposed alignments; i.e., the subsurface conditions in the project area are not significantly different from those disclosed by the explorations. If, during construction, subsurface conditions different from those encountered in the explorations are observed or appear to be present, we should be advised at once so that we can review these conditions and reconsider our recommendations where necessary. If there is substantial lapse of time between the submission of this report and the start of work at the site, or 21-1-20442-001 ·Rl-Rev.doc/wp/LKD 21-1-20442-001 2 SHANNON &WILSON. INC. if conditions have changed due to natural causes or construction operations at or adjacent to the site, we recommend that this report be reviewed to determine the applicability of the conclusions and recommendations considering the changed conditions or time lapse. This report was prepared for the exclusive use of the City and members of the design team. It should be made available to prospective contractors and/or the Contractor for information on factual data only, and not as a warranty of subsurface conditions, such as those interpreted from the exploration logs and from the discussion of subsurface conditions included in this report. Unanticipated soil conditions are commonly encountered and cannot fully be determined by merely taking soil samples from test borings or pushing probes. Such unexpected conditions frequently require that additional expenditures be made to attain properly constructed projects. Therefore, a contingency fund is recommended to accommodate such potential extra costs. Construction of HDD bores requires the expertise of specialty contractors and their own engineers or their consultant's engineering staff to understand the engineering consequences associated with the particular means and methods of the Contractor. As such, it is recommended that qualified engineers be part of the Contractor's team to interpret the significance of the subsurface conditions encountered and their potential impacts on the chosen means and methods. The scope of our services did not include any environmental assessment or evaluation regarding the presence or absence of wetlands or hazardous or toxic materials in the soil, surface water, groundwater, or air, on or below the site, or for evaluation of disposal of contaminated soils or groundwater should any be encountered. Shannon & Wilson has prepared Appendix D, "Important Information About Your Geotechnical Report," to assist the owner and members of the design team in understanding the use and limitations of our report. 2.0 SITE AND PROJECT DESCRIPTION 2.1 Site Description The proposed project is located in the vicinity of Maplewood Heights, an unincorporated residential area east of the City in King County, as shown in Figure I. Proposed sewer mains would descend from the top of the plateau, down the steep slope of the north valley wall, to the floor of the Cedar River Valley. These sewer mains would be constructed down the steep hillsides that lie on either side of 154th Place SE, an arterial descending from the plateau to the 2 l-l-20442-001-Rl-Rcv.doc/wp/LKD 21-1-20442-00 I 3 SHANNON &WILSON. INC. valley floor along the ravine of a small stream. We have designated these two sewer mains as the east and west alignments. Two alternatives arc under consideration for the west alignments. The proposed locations of the east and two west pipeline alignments are shown in the Site and Exploration Plan, Figure 2. The upland plateau is relatively flat but gently undulating and slopes to the south toward the Cedar River. The tributary stream is deeply incised into the edge of the plateau, and in the project vicinity it lies as much as 200 feet below the upland surface. Steep slopes flank the stream on both sides. The slope at the location of the proposed east alignment is approximately I 00 feet high and has an overall inclination of about 42 degrees from the horizontal. The west slope is approximately 170 feet high and has an inclination as steep as 40 degrees. 2.2 Project Description Maplewood Heights is currently served by septic systems. The Central Plateau Interceptor project would collect and convey sewer flow from the upland area of Maplewood Heights down to a major sewer trunk recently constructed to the south, where 154th Place SE intersects Jones Road. The two proposed sewer mains would be constructed down the steep hillsides on either side of 154th Place SE where they would join and continue southward along the road. Our evaluation addresses only the construction of the pipelines down the steep slopes. It is our understanding that the proposed sewer mains will be continuous, fuse-welded, high- density polyethylene (HDPE) pipe 12 or 15 inches in diameter. The proposed sewer main on the steep slope east of 154th Place SE would be constructed using HDD construction, and would likely be drilled from the bottom. The entry pit would be located west of l 54'h Place SE, between the roadway and the stream,and the bore would be drilled beneath the roadway and up the slope. System constraints require that this pipeline be located approximately 19 feet below ground at 1561h Avenue SE located at the top of the slope. A second sewer main would be constructed down the steep slope west of 1541h Place SE, along one of two alternative alignments. Both west alternative alignments would originate at a depth of about 10 feet at the cul-de-sac on l 52"d Place SE and extend eastward between two closely- spaced houses at the east end of the cul-de-sac. Both alignments would extend down the steep slope to near the driveway of the Stewart residence at 14665 154th Place SE, located at the base of the slope. 21-1-20442-001-RI -Rev .doc/wp/LKD 21-1-20442-001 4 SHANNON &WILSON. INC. Geometric and other constraints limited the construction options available for the west alignment. The two current west alternatives comprise: 1> Drilling from the cul-de-sac out to the slope face, approximately 50 feet below the edge of the plateau, using auger boring construction methods. Once daylighted, the alignment would bend southward, and the pipeline would be constructed down the slope to the Stewart's driveway by anchoring HDPE pipe on the ground surface. 1> Drilling from the cul-de-sac to the base of the slope face using HDD methods. The HDD alignment would daylight on the slope above the stream in line with the easement between two properties on the cul-de-sac. Shallow trenching would be used to construct the remainder of the pipeline southward to the driveway. For either alignment, the sewer main would be conveyed across the stream in a trench constructed in the existing driveway embankment that extends across the stream. 3.0 SUBSURFACE CONDITIONS The geology and subsurface conditions along the pipeline alignments were inferred from soil samples and information obtained from subsurface explorations, geologic reports and maps of the area, and soils exposed in a few locations along the edge of the plateau. The following sections include a description of the general geology, subsurface explorations and laboratory testing performed, and the soil and groundwater conditions interpreted to be present along the alignment. 3.1 General Geology The site is located at the edge of a broad upland area underlain by sediments deposited by one or more of the six glacial advances to occupy the Puget Lowland or by processes similar to those of the present day during intervening interglacial episodes. During the last glacial advance, known as the Vashon, the ice was about 3,000 feet thick in the Seattle area, which compacted the underlying deposits to a dense or hard state. The Vashon ice sheet receded from the area about 13,500 years ago, leaving the upland with low-rolling relief and a veneer of material not glacially overconsolidated. Since that time, present-day geologic processes have incised the deep ravine into the edge of the upland and deposited surficial soils within the ravine through the actions of streams and mass wasting. 21-1-20442-001-R l-Rev.doc/wp/LKD 21-1-20442-001 5 SHANNON &WILSON, INC. 3.2 Subsurface Conditions Our understanding of subsurface conditions that underlie the site is based largely on soil and groundwater data collected from three borings (B-1, 8-2, and 8-3), four hand borings (HB-1, HB-2, HB-3, and HB-4), and two test pit explorations (TP-1 and TP-2) performed specifically for this project. The locations of the subsurface explorations are shown in the Site and Exploration Plan (Figure 2). The logs of the subsurface explorations, along with sampling and classification methodology, are presented in Appendix A. The results oflimited geotechnical laboratory testing performed on selected soil samples are provided in Appendix B. The geologic deposits that underlie the site consist largely of Vashon and pre-Vashon glacial and nonglacial sediments that have been overridden by glacial ice one or more times and, as a result, are very dense or hard. These deposits arc generally overlain at the ground surface by a thin layer of Vashon or post-Vashon (Holocene) deposits that have not been glacially overridden. The geologic deposits that compose the upper portion of the subsurface below the east and west alignments are generally coarse-grained deposits of sand and gravel. Generally, finer-grained deposits constitute the lower portions of the subsurface. Our interpretation of the subsurface conditions is depicted on the generalized subsurface profiles shown in Figures 3 through 5. These profiles were constructed at approximate locations of the HDD alignments and auger boring/surface-mounted alignments. The subsurface conditions are summarized below. Most of the upper portions of the steep slopes and adjacent plateau areas are underlain by gravelly, silty sand to silty, sandy gravel (till-like soils and outwash). The uppermost soils that underlie the upland areas appear to be deposits of recessional outwash, which have not been glacially overridden. These soils were deposited by meltwater streams flowing from the melting ice front as the glacier retreated from the Puget Lowland. As encountered in the borings, these deposits ranged from 31 to 38 feet thick, and generally consist ofloose to very dense, clean to slightly silty, sandy gravel with layers of gravelly sand. The presence of scattered to abundant cobbles was inferred from drill action, and boulders commonly exist within recessional outwash deposits. Because of the large clast sizes, these soils commonly appear very dense based on blow counts, but may be relatively loose. These soils are relatively permeable. Because of drill mud loss and large clast size, drilling was difficult in these soils in boring 8-1 near the west alignment. Based on drilling conditions and soils observed in the headscarp of the 21-1-20442-001-R 1-Rev.doc/wp/LK.D 21-1-20442-001 6 SHANNON &WILSON, INC. recent landslide southeast of the east alignment, we anticipate that the recessional outwash underlying the west alignment are coarser grained than those underlying the east alignment. Till-like deposits and outwash underlie the recessional outwash. These coarse, granular deposits are similar in composition to recessional outwash and generally consist of silty, gravelly sand to silty, sandy gravel. Scattered cobbles and boulders may be present within these soils. Unlike recessional outwash, these deposits have been glacially overridden and are very dense. Till-like deposits and outwash were encountered in borings 8-1 and 8-3 extending to depths of86 and 95 feet below the ground surface (approximate elevations 270 and 255), respectively. Because of the large clast size and very dense condition, drilling was difficult in these soils. Till-like deposits commonly have characteristics that vary between those of till, which is relatively impermeable, and cleaner and relatively permeable outwash. Groundwater was encountered in the outwash, and seams of perched water are likely present within the till-like deposits. The lower portions of the hillsides and adjacent plateau areas appear to be underlain generally by finer-grained nonglacial deposits. As encountered in the borings, these soils commonly consist of silty, fine sand with lesser amounts of slightly clayey silt to silty clay and silty, fine to coarse sand. These deposits may vary considerably, both laterally and vertically, and channel deposits consisting of sand and gravel may be present sporadically throughout this geologic unit. Coarser-grained outwash deposits of sand and gravel were encountered in boring 8-1 below an elevation of about 200 feet. A void was apparently encountered in the sandy gravel at an elevation of 192 feet. The relatively level ground at the locations of the east HDD entry pit and the west HDD exit pit appears to be underlain by fill overlying alluvium. The fill may have been placed from past site grading associated with the construction of the Stewart's driveway and past road or utility construction along 1541h Place SE. The alluvium would have been deposited by the stream that parallels 1541h Place SE or by the Cedar River. The soils encountered in test pits TP-1 and TP-2 generally consist ofloose to very dense, sand and gravel with variable silt content. Although not easily distinguishable, the soils encountered at depth in the two test pits appear to be native deposits of alluvium. Cobbles, boulders, and wood debris were encountered in the two test pits. The very dense soils that underlie steep, hillside slopes have a relatively thin mantle ofless dense colluvial soils near the ground surface. Colluvium is the loosened rind of soil mantling most 2 l -1-20442-001-R I-Rev .doc/wp/LK.D 21-1-20442-001 7 SHANNON &WILSON. INC. steep slopes, which has moved downslope from the force of gravity. This layer consists of soils similar to the underlying soils from which they were derived. At the site, these soils consist generally of sand and gravel with variable silt content. As encountered in the hand borings, the layer of colluvium appears to be on the order of 5 to 8 feet thick. However, hard or very dense soils were observed below colluvium at depths of 3 to 5 feet in several locations in cut slopes along the abandoned dozer road. Wet ground from seepage was observed on the west slope at an approximate elevation of 240 feet. Wet conditions are also indicated by the presence of numerous cedar trees at and below a similar elevation along much of this slope. Although no seepage was observed on the east slope, seepage or wet conditions may be present, as inferred from vegetational patterns observed in historical aerial photographs of the site. 3.3 Hydrogeology The hydrogeology of the project area is characterized by the presence of groundwater in permeable, granular soils (sands and gravels) perched above less-permeable, finer-grained soils (mixtures of clay, silt and fine sand). Observation wells were installed in borings B-1 and B-3, and a VWP was installed in boring B-1 to evaluate groundwater conditions along the alignments. Screen and VWP depth, general boring information, and groundwater levels are summarized in Table A-1, in Appendix A. The locations of observation wells, the VWP, and measured groundwater levels are depicted in the boring logs in Appendix A, as well as in the subsurface profiles in Figures 3 through 5. Three aquifers appear to be present in the site area, one above the other, and they are termed the upper, middle, and lower aquifers. An upper aquifer is likely present, at least seasonally, in the recessional outwash that overlies till-like deposits. Groundwater is present near the base of the recessional outwash that underlies the east alignment, based on a well installed in till-like deposits just below the recessional outwash. This groundwater has an apparent static groundwater level at an approximate elevation of321 feet. No groundwater was observed in the recessional outwash in borings B-1 and B-2 in the vicinity of the west alignment, except for small amounts of water locally perched on Jess permeable seams. Seasonally, some water may be present at the base of the outwash, perched on top of the less permeable till-like deposits. 21-l -20442-00 I-RI -Rev.doc/wp/LKD 21-1-20442-001 8 SHANNON &WILSON. INC. No seepage corresponding to an upper aquifer was observed on the hillside along the east and west alignments; however, seepage was observed discharging from near the base of recessional outwash at a similar elevation at the head of the ravine approximately 1,000 feet southeast of boring B-3. The soils and water flow were revealed by a landslide that occurred in January 2006. The middle aquifer exists in the sand and gravel deposits that lie beneath the till-like deposits and overlie finer-grained, nonglacial lacustrine deposits. This aquifer is screened by the observation well in boring B-1 and exhibits a groundwater elevation of 279 feet. Seepage inferred at a similar elevation on the slope west of 154'1, Place SE likely originates from this middle aquifer. The middle aquifer is the source of water for the residents living in the property at the foot of the hill slope west of l 54'h Place SE. According to the Stewarts, the water source was developed approximately 40 years ago by hand augering about 30 feet into the slope at a location of observed seepage. The water collection pipe is located at an approximate elevation of 260 feet, which roughly correlates with the base of a layer of granular soil encountered in boring B-1 at an elevation of269 feet. Moreover, the property owners recount building the holding tank on clay, which is consistent with the observed lacustrine deposits underlying the granular deposits. An early HDD alignment under consideration had the drill path close to this groundwater-fed water supply. This alignment was later dropped from consideration because of potential HDD construction impacts to this water supply, namely reduces water quality or flow. To evaluate baseline water quality of this middle water-supply aquifer, one groundwater sample was collected from the observation well in boring B-1. The groundwater sample was analyzed for fecal coliform, petroleum-related hydrocarbons, and metals. The chemical analyses of the groundwater sample resulted in non-detections for fecal coliform and petroleum-related hydrocarbons (gasoline, diesel fuel, and lube oil). Analysis of dissolved metals resulted in low level detections ofbarium (28 micrograms per liter [µg/L]) and manganese (51 µg/L), with non-detection of the other metals analyzed (arsenic, cadmium, chromium, copper, lead, nickel, and zinc). The pH of the groundwater sample is within the natural range of5 to 8, at 7.7. Sampling procedures are described in Appendix A. The laboratory results are compiled in Appendix C and summarized in Table C-1. 2t-1·20442-00I-Rl-Rev.do<lwp/LKD 21-1-20442-001 9 SHANNON ~WILSON, INC. The lower aquifer exists in the slightly silty to silty sand unit observed only near the bottom of boring B-1, the deepest of the three borings. A VWP was installed at an elevation of 177.5 feet in boring B-1, and groundwater was measured at an elevation of 189 feet. 4.0 SLOPE STABILITY 4.1 Slope Stability Observations The scars of several shallow landslides were observed on stereo-pair, aerial photographs taken as far back as 1936. The larger landslide scars were located at the top of the plateau on steep slopes facing the Cedar River. Only a few landslides were observed on the slopes facing the stream that runs along l 54'h Avenue SE. The scars of these landslides appeared to be relatively small and shallow, except for one along a small ravine that is located on the east hillside about 300 feet south of the proposed east alignment. This landslide appears to have been shallow but may have been as much as 80 feet across. The photographs indicate that the landslide resulted in a debris flow that extended down the ravine to the road. While on site to conduct subsurface explorations, we performed a reconnaissance of the site and vicinity to look for evidence of past landsliding or conditions indicative of marginal instability. No active, large, or deep-seated landslides were observed during our reconnaissance or indicated by the aerial photographs. The trees present on the east and west hillside slopes generally have straight and vertical trunks 1 to 3 feet in diameter, suggesting no significant movement over the last 50 years or more. Evidence of past shallow landsliding or slumping was observed at two locations on the west slope, west of the proposed alignment. These landslides likely occurred in the looser colluvium that mantles the slope. In general, the slopes on both hillsides appear relatively stable but near the limit of stability. Disturbance of the slope soils, especially following periods of intense precipitation, would reduce their stability unless mitigation measures are utilized. In January 2006, a landslide occurred at the top of a ravine that lies southeast of the project area. This landslide occurred after weeks of very wet antecedent conditions related to near-record precipitation in the lowlands of Puget Sound. Large volumes of water flowed from near the base of recessional outwash. 21-1-20442-001-Rl-Rev.doc/wp/LK.D 21-1-20442-001 10 SHANNON &WILSON. INC. 4.2 Slope Stability Analyses Stability analyses were conducted using the computer program SLOPE/W (GEO-SLOPE International, Ltd., 2005). This program requires specifying the slope geometry, soil strength parameters, groundwater conditions, and instructions about critical slide plane searches. The analyses included performing a search for the most critical failure surface using the Bishop, Morgenstern-Price and Modified Janbu methods to determine the stability of the existing slope. The effect of earthquakes was evaluated by calculating the factor-of-safety (FS) using the pseudo-static method. In the pseudo-static method, the earthquake inertial forces are included in the analyses by assuming that an equivalent static horizontal force approximates them. This horizontal force is equal to the weight of the assumed sliding mass of soil multiplied by a pseudo-static coefficient. Based on studies by Makdisi and Seed (1978), the appropriate pseudo- static seismic coefficient is equal to about one-half of the peak ground acceleration (PGA). A pseudo-static coefficient equal to 0.15g was used in the slope stability analyses. The stability program calculates the FS against failure along either a specified slide plane or multiple potential slide planes. A FS of 1.0 is generally considered marginally stable. Higher values indicate greater stability, and lower values indicate instability or sliding. Generally, a FS against sliding under static conditions of at least 1.3 is desirable. A FS of at least 1.1 under seismic loading conditions is a generally acceptable value. The results of the stability analyses indicate a FS of about 1.5 and 1.1 under static and seismic conditions, respectively. The results are portrayed graphically in Appendix D. 5.0 CONSTRUCTION METHOD ALTERNATIVES Combinations of laying the pipe on the ground surface, trenching, and trenchless methods (HDD and auger boring) are feasible to descend the steep slopes present at the site. For the west side, we have considered two alternatives to reach 154th Place SE. The steep slopes along these west alternatives are between 33 and 38 degrees. The first alternative involves auger boring from the end of the 152nd Place SE cul-de-sac along the property lines and daylighting on the slope at about elevation 305 feet. The pipeline would continue down the slope with surface-mounted pipe to the driveway of the Stewart property. The second alternative consists of an HDD installation from the end of the 152nd Place SE cul-de-sac to the toe of the slope following the easement along the property lines. In our opinion, the auger bore and the surface-mounted 21-1-20442-001-Rl-Rev.doc/wp/LKD 21-1-20442-001 11 SHANNON ~WILSON, INC. alternative is preferable and is likely to have less construction difficulties. The HDD alternative would require that it be drilled from the top of the slope with the high risk of inadvertent returns at the toe of the slope and that the pipe be pushed down slope since there is no staging area available at the toe of the slope. On the east hillside, we considered only a single alignment that descends the steep slope to 154th Place SE utilizing HDD methods. The natural slope at this location is approximately 42 degrees. Plan views and profiles of the east and west alternatives are shown in Figures 2, 3, 4, and 5. 5.1 Trenchless Methods 5.1.1 Horizontal Directional Drilling (HDD) HDD consists of drilling a pilot hole, typically from the bottom of the slope upward to the top of the slope, and then pulling a product pipe through an enlarged hole. The pilot hole (commonly about 5 inches in diameter) is drilled while the depth and location of the drill head is monitored with a walk-along, location tracking system. After the pilot hole is drilled, the hole is reamed to a larger diameter, and the pipe is pulled back through the hole. To install a 12-inch HOPE pipe, the hole needs to be enlarged to about 18 inches. Bentonite slurry is used during the drilling and reaming operations to remove drill cuttings from the hole. Bentonite slurry circulates through the drill steel to the drill bit and returns with the cuttings in the annular space between the drill steel and the walls of the bore. The bentonite slurry also forms a cake around the borehole to help stabilize the opening. Drilling typically starts at the toe of the slope, where bentonite slurry is collected in a pit and then re-circulated. Drilling from the toe of the slope results in the slurry continually flowing from the drill bit to the toe of the slope, and the annulus around the drill steel is never completely full. The drill path starts typically at a slope inclination of 10 degrees below horizontal and gradually increases upwards in a circular curve, until it reaches a constant slope and then follows a circular reverse curve and levels off at a slope of 10 degrees to reach the ground surface. The radius of the vertical curve is a minimum of 525 feet for the west side HDD and 325 feet for the east side HDD. The minimum radius is controlled by the drill steel diameter and the pipe diameter. A larger radius will facilitate installation and lqwer pullback loads. 2 l -1-20442-00 I ~RI -Rev .doc/wp/LKD 21-1-20442-001 12 SHANNON &WILSON, INC. HDD pipe installation requires two staging areas. A slurry staging area at the bottom of the slope is required for the drilling machine and a pit, and a temporary pipe assembly area is required at the opposite end of the hole from the drilling machine. Generally, contractors prefer an area with a length equal to the total hole length with a width of approximately 12 to 15 feet to lay out and pre-assemble pipe sections for rapid installation of the completed pipe as soon as the hole is drilled. Pipe installation involves a rapid and continuous pull to reduce the risk of collapsing the hole. 5.1.2 Auger Boring Auger boring is a method of installing pipe by pipejacking from a shaft or pit using an auger to advance the hole. Auger boring is commonly known as jack and bore. The auger boring machine simultaneously jacks the casing pipe forward and rotates an auger inside the pipe. The auger excavates the hole and carries the soil back to the jacking pit where it is removed. In our opinion, auger boring could successfully be used above groundwater in the anticipated dense to very dense sandy gravel near the top of the west slope. Surface Mounted High-density Polyethylene (HDPE) Pipe At approximate elevation of 305 feet, the sewer pipe will transition from the auger-bored casing to surface-mounted HDPE pipe tied down with helical anchors. The anchors will stabilize the pipe and prevent it from creeping downhill. HDPE is durable and resists degradation caused by ultraviolet light. HDPE can be heat fused in the field, producing reliable and strong joints. 5.2 Trenching Methods Trenching methods will be used along 154'h Place SE and across the culvert at the driveway of the Stewart residence. Trenching will require temporary modular shoring meeting State of Washington safety requirements. 6.0 ENGINEERING CONSIDERATIONS AND RECOMMENDATIONS The steep-slope portion of the east sewer main is to be constructed using HDD. The west sewer main may be constructed using HDD or a combination of auger boring and surface-mounted pipe. Engineering recommendations for utilization of each of these methods for the project are 2l-1-20442-001-R 1-Rev.doclwp/LKD 21-1-20442-001 13 SHANNON &WILSON, INC. presented below. Because of the complexity of the HDD construction method, most of our recommendations pertain to this method. 6.1 Horizontal Directional Drilling (HDD) 6.1.1 Soil Behavior Along Bore Path As discussed in Section 3, the slopes along the proposed alignments are underlain by fine-grained soils in the lower half of the slope (up to an elevation of about 290 feet) and more granular soils in the upper half. The fine-grained soils largely consist of sandy silt to silty, fine sand with some clayey silt and silty clay; the granular soils consist of sandy gravel, gravelly sand, sand, and gravel. Cobbles (3 to 12 inches in diameter) and boulders (greater than 12 inches in diameter) are likely present in the recessional outwash and till-like deposits, which would be obstacles for the installation of pipe by the HDD method. The drillhead will not be capable of drilling through boulders, and the presence of cobbles will hinder the reaming operation. If a boulder is encountered, the drill path would need to be modified. The drill steel would be retracted for about 15 feet and steered deeper to avoid the boulder. Because of the potential of encountering boulders and modifying the drill path, there needs to be flexibility in the location of the HDD exit point. In general, HDD is most successful in soft or silty and clayey soils and even rock, all of which form relatively stable boreholes. In non-cohesive soils, such as sand and gravel with cobbles and boulders, HDD installations have experienced serious problems because of caving holes and jammed and lost drill bits and rods. HDD holes in coarse granular deposits usually require additional time and preparation procedures, such as pulling hole compactors through the completed bore. In granular soils, the drilling fluid helps stabilize the circumference of the hole and prevent collapse by forming a "cake" of mud-impregnated soil (mud cake or filter cake) around the periphery of the drilled hole. The drilling fluid generally establishes a more capable mud cake in silt and sand. Gravel. layers may be too coarse to rapidly establish a stabilizing cake, particularly where groundwater is flowing into the drill hole. Sidehill HDD bores are typically drilled uphill, where possible, to reduce the chance of hydraulically fracturing the soil at the toe of the slope, which could result in a spill. Mud cakes can be developed by using hole compactors as the bore fluid runs by gravity out of the hole as fast as it is injected. The highest risk for these types of bores is the chance that the bore will drill 21-1-20442-00 J • R 1-Rev.doc/wp/LKD 21-1-20442-001 14 SHANNON &WILSON. INC. up into perched water in a granular deposit. The sudden release of perched groundwater into the bore can destabilize the surrounding ground and result in soil flowing into the bore annulus rapidly enough that the drill steel becomes locked. This problem can result in loss of both the bore and the drill tools. Although a final bore diameter of 18 inches is well within the capabilities of current drilling techniques, the lack of a stable mud cake in gravelly ground will likely promote caving and collapse of the hole. Collapse of gravelly soils during pulling of the pipe into the hole, behind the reaming tool, could result in locking of the casing in the hole. Although, an HDD installation for the project may experience difficulties, the problematic soils are located near the top of the slope. After the pilot hole is drilled and reamed, an approximately 20-foot-long casing pipe may be installed from the top of the hole to prevent caving of the recessional outwash. Ifa boulder is found within 15 feet of the ground surface, it could be removed by excavating with a backhoe and backfilling the excavation with select material. Selection of an experienced HOD contractor who has worked in the Seattle area is important for this installation. Ground conditions are likely to be somewhat unfavorable for HDD in the upper one-third to one-half of the hillsides because of the potential presence of cobbles and boulders. Their presence could cause difficulties and add to construction costs. However, King County's Fairwood Interceptor project, which incorporated HDD installation, was recently completed on the opposite side of the Cedar River valley. The HDD installation was successfully completed through soils that we anticipate are similar to those underlying the east and west alignments, even though the diameter of the installed pipe was more than twice as great as that proposed for this project, and the length of the HDD drill path for that project was about 6,000 feet long, which approaches the current limits of the technology. 6.1.2 Pipe Friction During Pull-back Friction along the pipe is difficult to estimate, especially when drilling from the toe of the slope while the annulus outside the pipe is not completely full of slurry. Total force needed to pull the pipe is largely dependent on the Contractor's installation technique including hole reaming and preparation. Typically, the Contractor estimates friction based on experience. Factors affecting the frictional force include relative movement between the pipe and bore wall, consistency of pipe movement during the pulling operation, area of soil contact, soil contact 21-1-20442-001-Rl-Rev.doc/wp/LKD 21-1-20442-001 15 SHANNON &WILSON. INC. pressure of the bore wall on the pipe, pipe buoyancy, capstan effects from micro and macro curvature of the bore, soil properties, and frictional force on the ground surface or on the rollers developed while pulling the pipe to its entry pit. Preliminary calculations utilizing Drill path software (Maurer Technology, 2001) for the east side HDD indicate that pull-back loads will be less than I 0,000 pounds. The Contractor should provide an estimate of the total amount of force anticipated to pull the product pipe through the directional bore. The typical pull-back capacity required is at least twice the weight of the product pipe or the drill steel, whichever is higher. Calculations or their experience should support the estimate and address the potential for buckling of the pipe. Experience should be supported by case histories including measured loads for a similar project. We also recommend that the contract be developed such that the Contractor is required to verify that the pipe is acceptable prior to payment by checking the final installed diameter. Pull-back forces should be measured by the Contractor, recorded, and transmitted to the project engineer for evaluation during construction. 6.1.3 Hydraulic Fracturing Hydraulic fracturing occurs when slurry pressure in excess of the total stress in the ground is applied to the walls of the bore. Fracturing the soil can release slurry into the environment surrounding the bore through cracks in the ground. Cracks extending to the ground surface may result in a release of slurry to the ground surface (inadvertent drilling fluid release). Hydraulic fracturing near the base of the steep slopes could release slurry into the stream or ditches, causing unwanted environmental effects during construction. Inadvertent drilling fluid release should be expected to occur at the end points of the bores unless positive containment is provided, such as a casing. Contractors often excavate a pit downhill or in the vicinity of the entry and exit points to collect the slurry from localized fracturing at the ends of the bore. For this project, we recommend that the Contractor install casing at the entry of the west bore to contain slurry and prevent collapse of the bore. The casing should extend through the layer of recessional outwash. East of 154th Place SE, this layer of sandy gravel seemed likely to have fewer cobbles and boulders, as inferred from drilling action and soils observed in the scarp of a recent nearby landslide; therefore, we do not anticipate the need for a casing on the east side HDD. 21-1-20442-001-Rl-Rev.doc/wp/LKD 21-1-20442-001 16 SHANNON &WILSON, INC. Hydraulic fracturing is a concern mainly near the bore entry and exit points. However, hydraulic fracturing may occur at any location along a bore path if (a) the slurry return path is blocked by squeezing or collapsed ground, as typical slurry pumps have very high pressure capabilities, or (b) the dynamic head within the bore becomes excessive due to hydraulic properties of the slurry under borehole conditions. These two conditions are difficult to design for, but may be monitored to reduce the chance of inducing a fracture and to control the amount of slurry Jost through a fracture should it occur. For HDD installations proposed for this project, hydraulic fracturing and inadvertent slurry release is most likely to occur near the base of the steep slope during the drilling of the west alignment because of the slurry pressures likely to develop from drilling downhill. A release of slurry to the ground surface at this location could flow to the stream adjacent to 1541h Place SE. Inadvertent drilling fluid release should be anticipated even with the best of designs and experience. We recommend that the Contractor provide a contingency action plan for remediation should an event occur. The plan should include methods for identifying when an event has occurred, when and who needs to be notified, and what will be the immediate action by the Contractor to control the event. Long-term cleanup, if necessary, will depend on the nature of the event and can be decided at a later time based on site-specific conditions. 6.2 Auger Boring To perform the auger boring, a jacking pit would need to be constructed in the cul-de-sac to a depth of at least 10 feet. For the 12-to 15-inch-diameter sewer pipe, we recommend that the casing pipe be 24 inches in diameter. This will allow for cobbles up to about 10 inches in diameter to be excavated with the auger. As currently proposed, the auger boring would exit the slope just above the abandoned dozer road at an approximate elevation of about 305 feet. For this alignment, we estimate that the auger boring would have a length of about 460 feet and would have a downward inclination of 6 degrees from the jacking pit at the cul-de-sac. Auger boring in a downward inclination should only be performed above the water table because the auger will not be able to withdraw wet, gravelly sand. Groundwater was not observed in the recessional outwash in borings B-1 and B-2; however, small amounts of water could be perched locally within or at the base of the recessional outwash, at least seasonally. Based on the borings and on observations of the cut slope of the dozer road and of vegetation on the slope, we expect 2 l-l -20442-00 I -R 1-Rev.doc/wp/LK.D 21-1-20442-001 17 SHANNON &WILSON, INC. that the proposed exit point of the auger boring is located above the top of any significant groundwater. This is a relatively Jong drive (460 feet) for an auger bore. The Contractor may want to install a larger casing pipe to match his equipment capabilities. A steerable head should be installed at the beginning of the pipe and the pipe needs to be monitored with a liquid level system or a laser system that is used periodically while the auger is retrieved. 6.3 Surface-mounted High-density Polyethylene (HDPE) Pipe Based on the results of the subsurface explorations and our engineering analyses, we developed geotechnical recommendations to assist in the design and construction of the portion of the sewer pipeline that may be installed at grade on the steep slope, with the exception of top and bottom of slope. The portion of the pipeline at the bottom of the slope transitions to below grade and will be installed by trenching. Based on our slope stability analysis, it is our opinion that the slope could support the proposed sewer pipeline and remain stable. It is our opinion that a surface-mounted HOPE pipe would be appropriate for descending the west slope. The pipe should be installed with an anchor system at the top of the surface-mounted pipe to prevent the line from being pulled part by soil creep or other gravitational effects. The pipe could be supported with helical or Manta Ray anchors. Figure 6 (2 sheets) illustrates an example of a suitable anchoring system. If anchored in this manner, the pipe can withstand shallow landsliding that could occur beneath the pipe. To accommodate thermal expansion, the pipe could be placed so that there are slights bends to either side of the axis of the pipe as it descends the slope. If the pipe is snaked in this fashion, the pipe should be staked at locations of bends to restrain the pipeline against lateral loads. These anchors could be straight, nail-type anchors. The joints of the pipe should also be durable and able to carry axial loads and accommodate flexural deformation of the pipe. Welded or through-bolted, flanged joints are examples of suitable joints. Surface preparation for support of the at-grade portion of the pipe requires only removal of vegetation, debris, and any hard, sharp objects. The pipe should be graded to prevent sediment accumulation in the pipe that could eventually block or reduce its capacity. 2 l -1-20442-00 I -RI -Rev .doc/wp/LK.D 21-1-20442-00 I 18 SHANNON &WILSON. INC. 6.4 Trenching We anticipate that the fill and near-surface native soils observed in subsurface explorations can be excavated using conventional excavating equipment such as rubber-tired backhoes or tracked hydraulic excavators. Excavation in such soils should not require unusual equipment or procedures. Cobbles, and possibly boulders, are likely to be encountered, and considerable seepage into the trench at the bottom of the slope may occur. The Contractor should anticipate their presence. Unshored temporary excavation slopes may be used where planned excavation limits will not undermine existing structures or extend beyond construction limits. The sides of the excavation should be sloped back as needed to provide a safe, stable slope. Our recommendations for trenching alternatives are shown in Figure 7. Consistent with conventional construction practice, temporary excavation slopes should be made the responsibility of the Contractor, since the Contractor is able to observe the nature and conditions of the subsurface materials encountered, including groundwater, and has the responsibility for methods, sequence, and schedule of construction. For planning purposes, and for excavations less than about IO feet deep, we recommend temporary excavation slopes in the near-surface loose soils be no steeper than 1.5 Horizontal to I Vertical (I.SH: 1 V) and those in underlying dense to very dense soils be no steeper than I H: IV. Where less competent soils or seepage zones are encountered, such as at the base of the west slope, flatter slopes may be required. Temporary shoring may be required for the trench excavation to protect existing utilities and structures and/or provide a work environment that complies with applicable safety regulations. If instability is detected, slopes should be flattened or shored. For temporary shored excavations, construction practice in the Seattle area generally includes trench boxes, interlocking steel sheet piles, a combination of soldier piles and horizontal lagging, and/or steel plates and internal bracing walers, although other methods of trench support are possible. For relatively shallow excavations ( e.g., less than about 10 feet), a trench box is likely the most economical shoring system; however, it should be understood that a "standard" trench box does not usually provide adequate support of the trench excavation slope, but instead only provides safety for workers in the trench. Because the trench box typically is placed after excavation, a significant amount of soil deformation commonly takes place alongside the excavation limits. Ground movements can be severe, especially in the presence of groundwater and in near-surface or loose soils. The 2 t-1-20442--001-R 1-Rev.dociwp!LKD 21-1-20442-00 I 19 SHANNON &WILSON, INC. Contractor should be held responsible for all damages related to ground movements. Regardless of the construction method used, all excavation work should be accomplished in compliance with applicable local, state, and federal safety regulations. 6.4.1 Surface Water and Groundwater Control Temporary dewatering may be required for excavations made at the bottom of the slope. Based on the conditions we observed at the ground surface and in the explorations, it is our opinion that groundwater inflows into trenches and excavations are likely but could be kept dry using sumps. If excessive and continual seepage is encountered during construction, a temporary interceptor trench located upslope from the trench excavation could be effective. All surface water should be diverted away from open excavations. 6.4.2 Pipe Bedding and Initial Backfill Normal pipe bedding procedures should generally prove satisfactory along the proposed sewer alignment. For conventional pipe installation, i.e., pipe that is not pile-supported, disturbance of subgrade soils at the bottom of the trench excavation because of construction equipment and activities will affect support of the proposed pipe. It is anticipated that much of the soil exposed at the bottom of the excavations will be moisture-sensitive and easily disturbed. The Contractor should take all necessary steps to protect the subgrade from becoming disturbed. The recommended typical pipe trench section for bedding and backfilling conventional pipelines in the dry is shown in Figure 7. Based on the soils encountered in the borings, the native soils are moisture-sensitive and may become unstable in wet conditions. If these soils become unstable during excavation, they should be overexcavated and replaced with the recommended pipe bedding material. Bedding material for flexible pipe (HDPE) should be clean, granular materials meeting the gradation requirements specified in Section 9-03.12(3) of the 2004 Washington State Department of Transportation (WSDOT) Standard Specifications or equivalent. Bedding should be at least 4 inches thick below the invert of the pipe and extend up the haunches of the pipe to the 120 degree arc line of the pipe (a height above the invert equal to 0.25 times the outside diameter). Initial backfill material should meet the gradation requirements for granular bedding material. The bedding and initial backfill materials should be placed in loose lifts of 4 to 6 inches and carefully worked under and around the pipe by means of shoveling, vibration, trench tamping equipment, or other approved procedures. The bedding and 21-1-20442--00 I-RI-Rev .doc/wp/LKD 21-1-20442-001 20 SHANNON &WILSON. INC. initial backfill should be compacted to at least 92 percent of its maximum dry density (as determined by the American Society for Testing and Materials ( ASTMJ test designation: D 1557). Heavy mechanical compaction equipment should not be used over the pipe until the bedding material and initial backfill are at least 1 foot above the crown of the pipe. 6.4.3 Subsequent Backfill and Compaction All subsequent trench backfill where settlements are to be minimized should be structural fill. In general, we anticipate that most of the on-site soils to be excavated should be suitable for reuse as structural fill during dry weather, provided it is free of organics, cobbles and boulders, debris, rubbish, and other deleterious material. Either selectively stockpiled, carefully segregated, on-site fill materials or imported structural fill may be used. During wet weather, the native sandy gravel/gravelly sand soils could be used as backfill, provided the fines (soil particles finer than the No. 200 sieve) do not exceed 5 percent, based on the minus '%-inch fraction of the soil. Where wet, the soils would probably not be suitable for reuse at any time of the year. If it is necessary to import structural fill, the imported material should meet the gradation requirements of Bank Run Gravel for Trench Backfill (WSDOT/American Public Works Association [ APW A] 9-03.10) or an approved substitution. The Wet Weather Considerations section of this report presents recommendations for materials and construction procedures for wet weather or wet conditions, no matter what time of year. We recommend that subsequent backfill be placed and compacted in lifts with a maximum loose thickness of IO inches for heavy equipment compactors or 6 inches for hand- operated mechanical compactors. Trench backfill should be compacted to a dense and unyielding condition, and to at least 90 percent of the maximum dry density as determined by ASTM Designation: D 1557 (Modified Proctor) in nonstructural areas where post-construction settlements are tolerable. Backfill in areas underlying paved surfaces where settlements are not desirable should be compacted to at least 95 percent. 6.5 Wet Weather Conditions Wet weather generally begins about mid-October and continues through about May, although rainy periods may occur at any time of year. Some of the soil at the site contains sufficient silts 21-1-20442-001-Rl-Rev.doc/wp/LKD 21-1-20442-00] 21 SHANNON &WILSON. INC. and fines to produce an unstable mixture when wet. Such soils are susceptible to changes in water content, and they tend to become unstable and difficult or impossible to compact if their moisture content significantly exceeds the optimum. If earthwork at the site continues into the wet season, or if wet conditions are encountered, we recommend the following: ~ The ground surface in and surrounding the construction area should be sloped as much as possible to promote runoff of precipitation away from work areas and to prevent ponding of water. ~ Work areas or slopes should be covered with plastic. The use of sloping, ditching, sumps, dewatering, and other measures should be employed as necessary to permit proper completion of the work. ~ Earthwork should be accomplished in small sections to minimize exposure to wet conditions. That is, each section should be small enough so that the removal of unsuitable soils and placement and compaction of clean structural fill can be accomplished on the same day. The size of construction equipment may have to be limited to prevent soil disturbance. It may be necessary to excavate soils with a backhoe, or equivalent, located so that equipment does not traffic over the excavated area. Thus, subgrade disturbance caused by equipment traffic will be minimized. ~ Fill material should consist of clean, well-graded sand and gravel soil, of which not more than 5 percent fines, by dry weight, passes the No. 200 mesh sieve, based on wet-sieving the fraction passing the '4-inch mesh sieve. The gravel content should range from between 20 to 60 percent retained on a No. 4 mesh sieve. The fines should be nonplastic. ~ No soil should be left uncompacted and exposed to moisture. A smooth-drum vibratory roller, or equivalent, should roll the surface to seal out as much water as possible. ~ In-place soils or fill soils that become wet and unstable and/or too wet to suitably compact should be removed and replaced with clean, granular soil. ~ Grading and earthwork should not be accomplished during periods of heavy, continuous rainfall. 6.6 Erosion Control The Contractor should employ proper erosion control measures during construction, especially if construction takes place during wet weather. Covering work areas, soil stockpiles, or slopes with plastic; sloping; ditching; sumps; and other measures should be employed as necessary to permit proper completion of the work. Bales of straw and/or geotextile silt fences should be appropriately located to control soil movement and erosion. 2 l-1-20442-001-R 1-Rev.doc/wp/LKD 21-1-20442-001 22 SHANNON &WILSON, INC. We recommend that areas disturbed by construction activities should be hydroseeded and then covered with an erosion-control blanket. An erosion-control blanket is recommended to (a) protect the bare soil face against erosion until vegetation is established; (b) reduce runoff velocity for increased water absorption by the soil, thus promoting long-term survival of the vegetation cover; and (c) reinforce the root system of the vegetative cover. We recommend using a permanent erosion-control, turf-reinforcement mat consisting of UV-stabilized synthetic fibers and filaments processed into a permanent, high strength, three-dimensional matrix. The placement of the erosion-control blanket should begin at the top of the slope (slope having a bare soil face) by anchoring the blanket in a 12-inch-deep by 12-inch-wide trench. The trench should be backfilled and compacted after stapling the blanket to the slope face. The blanket should then be rolled down the slope. We recommend that the staples have a minimum length of 12 inches. Stapling the adjacent rolls of the blanket should be done in accordance with the manufacturer's recommendations. Periodic maintenance of the erosion control blanket should be anticipated until vegetation is well established. 7.0 CONSTRUCTION CONSIDERATIONS Construction considerations for HDD installations and a more detailed description of the HDD installation procedure follows. The HDD method involves drilling a pilot hole along a designed path from entry to exit point. The pilot hole is typically less than 1 foot in diameter and follows the design centerline of the proposed pipeline, within a specified horizontal and vertical tolerance. The pilot hole is drilled using an HDD drill rig that pushes the directional drill bit and drill rods into the ground. Drilling is advanced by either jetting a hole using high-pressure drill fluid or by drilling the hole with a mud motor using high-pressure drill fluid. Steering is accomplished by aiming the jets at one quadrant of the bore to cut a hole in a specific direction or by aiming the mud motor drill bit toward the desired path. Mud motors have a bend in the housing that permits the drill bit to be directed at a pre-specified angle from the drill rod centerline path. The drill rods are then pushed into the hole, and the rods follow the desired direction of the drill bit. Bentonite and/or polymer drilling mud (slurry) is pumped down the center of the drill rods. The slurry acts (a) as a coolant, (b) as a fluid counteracting pressure that helps maintain an open hole, and (c) as a carrying fluid to wash soil cuttings back to the surface. The slurry returns along the 21-1-20442-001-R 1-Rev .doc/wp/LKD 21-1-20442-001 23 SHANNON &WILSON. INC. drilled path outside of the drill rods to the ground surface. A slurry separation plant at the surface filters out the soil cuttings and recirculates the bentonite slurry back through the drill rods. The position of the pilot hole is measured by a directional monitoring device (sonde) located behind the drill bit that registers angle, rotation, and direction (azimuth). Measurements are typically obtained at 15-or 30-foot intervals, which correspond to one-half or the full length of a standard drill rod. Several systems are available to transmit and detect this data, including walkover, wireline, and electromagnetic systems. These guidance systems typically allow for immediate feedback of the drill position so that steering adjustments can be made. A more accurate system is the wireline inductance system, which requires the placement of an induction coil wire on the ground surface above the bore path. A construction easement along the bore path is needed to allow for temporary placement of these electromagnetic guidance wires on the ground surface during drilling of the pilot bore. These wires also need to be accurately located by surveying. Upon reaching the exit point, the drill bit is removed and a reaming tool is attached to the drill string to enlarge the hole. The drill rig rotates and pulls the reamer back into the bore to increase the borehole size while the slurry circulation system is used to remove the soil cuttings. The reamer typically increases the diameter by I foot during each reaming pass, at the discretion of the Contractor. Tail rods are attached to the drill string and follow the reamer into the bore. Upon reaching the original entry point, a larger reaming tool is attached to the tail rods, and a second reaming pass is made. This cycle is repeated until the bore reaches the design size. In order to reduce skin friction during pull-back of the product pipe, the design size is typically 1.5 times the product pipe diameter. The Contractor chooses a final bore diameter that provides the best likelihood for successfully installing the product pipe, weighing the lower friction of the larger-diameter bore against the increased risks associated with constructing, and maintaining a larger-diameter open bore. The product pipe is typically pulled back into the bore from the exit point once the bore reaches the design size. This typical procedure is proposed for the east alignment. At the west alignment, the product pipe will be pushed into the bore from the entry point at the cul-de-sac. Prior to placement, the entire length of the product pipe is typically assembled as a single string. It is desirable to have a fully-assembled, continuous string of product pipe to minimize static 21-1-20442-001-R 1-Rev.doc/wp/LKD 21-1-20442-001 24 I SHANNON &WILSON, INC. friction forces that develop during pauses while pulling. Where space is restricted, segments can be fused or welded together during the pulling process; however, the fusion process and the resultant pause in the pull-back operation increase risk and add cost to the project. The ideal staging area requires a Jong continuous area in line with the bore path and equal to the final length of the product pipe plus about I 00 feet to work around the ends of the pipe. The curvature of this staging area off the pilot bore direction cannot exceed the allowable bend radius of the product pipe. Note that extremely high forces may be required to bend and hold the pipe at its minimum allowable radius. Once the bore has been prepared and a hole opener has successfully been pulled through the bore to verify that the hole is open and stable, the product pipe is attached to a pulling assembly at the pilot bore exit point or at the entry point. It is desirable to pull or push the product pipe in one continuous operation to minimize friction in the borehole and reduce the risk of getting the pipe stuck during the process. The slurry in the bore not only continues to maintain an open hole, but also acts to lubricate the product pipe during pull-back. The Contractor must also monitor the integrity of the product pipe by maintaining a safe pull-back force to prevent tensile failure. For this project, the Contractor must maintain the product pipe full of water to prevent its collapse. To control the pipe radius during pull-back, the Contractor typically uses side booms or cranes and rollers to support the pipe in a smooth, continuous entry arc. Buoyancy of the produce pipe must also be considered during pull-back, which is typically counteracted by filling the pipe with water. We recommend that the following information be developed and included in the construction plans and specifications. 7.1.1 Staging Areas The maximum permissible area for Contractor operations should be delineated as a staging area on the project drawings. Staging areas at both ends of the bore need to be sufficient for equipment and materials storage, drill staging, and pipe receiving and assembly. They must also be truck-accessible. At the bore entry point, a drill staging area should be a minimum of30 feet wide by 60 feet long and have a minimum of25 feet clear, in-line distance with the bore path from the entry point for positioning the drill rig. For the east HDD, there seems to be sufficient staging area on the west side of 1541h Place SE with minor grading. 21-1-20442-00 1-RI-Rev. doc/wp/LKD 21-1-20442-001 25 SHANNON &WILSON, INC. For the east alignment, where the product pipe is to be pulled back into the bore, the exit staging area also should be equal to the length of the product pipe and sufficiently wide (20 feet minimum) to allow equipment movement along the pipe during assembly. For the west alignment, a pull-back area is not needed but sufficient room needs to exist to make a connection to the trench portion of the alignment. 7.1.2 Fixed Entry and Exit Points Because the HDD pipeline must interface with the trench portions of the pipeline at specific manhole locations, the specified locations of the HDD at the manholes should be achieved by the Contractor within a 2-foot radius of the specified points, and within ±1 foot of the design entry elevations. Although tighter targets are possible, such specification would likely increase the project cost. We recommend that construction be sequenced such that the trenching follows the HDD bores, to allow for a more economical adjustment of the connections should the bore location deviate from the design location. 7.1.3 Corridor Width We recommend acquiring a temporary easement width along the design bore path during construction of± 15 feet, minimum, centered on the design bore path to allow for placement of guidance wires or tracking receiver at the ground surface. This easement needs to allow sufficient foot access for construction personnel above the bore path for guidance tracking, surveying, and for the observation and clean-up of any inadvertent drilling fluid returns that might occur during drilling. 7.1.4 Corridor Depth The minimum depth of cover over the HDD pipeline is dictated by hydraulic fracturing considerations. The maximum depth of embedment for a water-filled HDPE pipe is approximately 80 feet (to be verified by pipe manufacturer) to prevent long-term buckling failure. For a pipe constructed in this range of depths, the pipe cannot be allowed to become empty of water during installation or operation nor can it be subjected to a reduction in pressure below static heads such as can be developed by pump suction during pump startup, or the pipe runs the risk of collapse by buckling. Bore depths may be limited by project hydraulic 2I-1-20442-001-R 1-Rev.doclwp/LKD 21-1-20442-00 I 26 SHANNON ~WILSON. INC. considerations. The project hydraulic engineer should set minimum gradelines or elevations for the pipeline, if necessary. 7.1.5 Tolerances Vertical and horizontal tolerances for the product pipe are recommended to be within ±3 feet of the Contractor's design line and grade. The Contractor should be required to provide a submittal of his design, based on the above recommendations and project specifications. There should be no bends in the installation that cause stress in the pipe beyond the maximum allowable pipe stress recommended by the pipe manufacturer. A general rule of thumb for HDPE pipe is a minimum 50 feet of radius per 1 foot of pipe outside diameter. The planned drill paths have larger radii that exceed this requirement. We recommend that the project hydraulic engineer assess these tolerances for compliance with the project design parameters and add maximum allowable grade deviation tolerances, if necessary. 7.1.6 Tracking System We recommend that the tracking and guidance system be capable of working within the tolerances described above. Furthermore, we recommend that a Contractor submittal describes their proposed tracking and guidance system, along with an estimate as to the accuracy of installing the pipeline based on using the selected tracking system. The minimum acceptable tracking system accuracy should be ±2 percent of the depth to the sonde. We recommend that a wireline inductance system, such as the Tm-Tracker system by Honeywell, or equivalent, be utilized for guidance on this project. This system has a horizontal and vertical accuracy of approximately 1.5 percent of the depth to the sonde. Surface receivers are acceptable if their range is within the anticipated drillhole depth (80 feet). 7.1.7 Disposal of Spoils We recommend that the Contractor be responsible for the removal, disposal, and associated costs of all drilling-related spoils ( drilling mud, excavated soil, and slurry-stabilizing additives) from the site. Such spoils tend to be more fluid than in situ soil and, therefore, are difficult to haul by truck. Additionally, such spoils do not dry very quickly, sometimes taking 21-1-20442-001-RI-Rcv .doc/wp/LKD 21-1-20442-001 27 SHANNON &WILSON. INC. years, which can make spoil disposal difficult or expensive. If possible, the owner may consider providing a disposal site, which could offer the project a significant cost savings. 7.1.8 Pipe Characteristics The use of HDPE pipe is proposed, which is inert to soil and water corrosion and allows for greater curvature in a directional bore. The failure mechanism for HDPE pipe is most commonly by buckling. Buckling capacity is a function of external pressure magnitude and configuration, tensile stress in the pipe, HDPE temperature, and internal pressure. The two critical conditions for design are long-term stability and short-term stability. Long-term stability is controlled by the long-term HDPE modulus and the differential stress between the external soil and groundwater loads and the internal minimum water pressure. Assessment of the Jong-term pipe stability is the responsibility of the pipe manufacturer. The critical short-term stability period occurs during pull-back when there is maximum tensile stress in the pipe. The Contractor controls this condition, and it is typically the Contractor's responsibility to maintain stability during short-term loading. Preliminary estimates of installation tensile stresses and internal and external stresses indicate that DR-13.5 HDPE pipe (Plexco PE 3408) has a factor of safety of 2 for installation. The designer in coordination with the HDPE pipe manufacturer should make the final selection ofHDPE wall thickness. As short-term instability results in relatively quick collapse of the pipe, the Contractor should be required to verify the integrity of the pipe both by calculations and by pulling a dimensioned pig (i.e., tapered plug) though the pipe after completion. The pipe manufacturer should develop the pig dimensions, which should be provided to the Contractor for its purchase or fabrication. The maximum tensile stress on the pipe occurs during pull-back, which is a function of construction methods and soil conditions, and is the Contractor's responsibility. Pipe stress will be reduced by filling the pipe with water during installation. The Contractor's calculations indicating maximum permissible pull-back force and equipment capacity should be submitted to the pipe manufacturer for review and approval. 21-1-20442-00 l -R 1-Rev.doc/wplLKD 21-1-20442-001 28 I SHANNON &WILSON, INC. 7.1.9 Connections Because of the length of the bores and available pipe lengths, the product pipe will require fusion welding of pipe sections. We recommend that all connections be designed to take the full tensile and bending capacity of the pipe section and that all connections be tested to verify the design requirements as part of the final acceptance of the pipe. This is typically done by subjecting the installed pipe to hydrostatic testing before and after installation. The designer needs to develop a hydrostatic testing program for pipe acceptance. We recommend that the testing program design include review by the manufacturer of the pipe. The HOPE pipes will be installed from the ground surface and going through the locations of the manholes. Therefore, the HOPE pipe needs to be connected to the manhole walls, and the rest of the HOPE between the manhole and the ground surface can be removed or abandoned in place. The void left by the abandoned pipe or drill hole needs to be backfilled with a sanded grout. 7.1.10 Obstructions Cobbles or boulders are likely present along the east and west alignments. In addition, there could be lenses of relatively clean sand in the alluvium (Ha) that may flow into the bore, causing the drill pipe to get stuck. Fill is expected to be encountered at the start of the east bore at the ground surface. The fill may include manmade debris requiring excavation to remove. 7.1.11 Buried Utilities The bore paths cross or underlie one or more streets, which contain utilities that may or may not be shown on the project drawings. The utilities were probably installed by conventional trenching methods at depths between 5 and IO feet. Trenching often weakens the ground in the area adjacent to and above the trenches. Grow1d loss resulting in settlements during the drilling and reaming process, as well as slurry penetration due to hydraulic fracturing can damage the utilities. We recommend that all utilities be accurately located and their condition assessed prior to construction. Further, we recommend that the HOD bore path be located at least 5 feet below all utilities. The clearance may be reduced on a case-by-case basis (depending on the slurry pressure used to drill the bore), but the risk of damage increases with decreasing clearance. In no case should a bore intersect a utility trench fill. 21-1-20W2-001-R I-Rev.doc/wp/LKD 21-1-20442-001 29 SHANNON &WILSON. INC. Even if these recommendations are followed, there is still some risk that the drilling and reaming operations could cause settlement of the ground around the utilities or streets because of ground loss. Damage to utilities could also be caused by penetration of slurry into trench fill or into utilities such as sewers. Slurry could also plug drainage systems. The specifications should state allowable ground settlements for the streets, utilities, and any other sensitive facilities. 7.1.12 Settlements In our opinion, ground loss within the bore may be difficult to measure, but will eventually lead to settlement above the area of ground loss. Studies of tunneling indicate that the amount of settlement and the width of the affected area along the bore path are dependent on the volume of ground loss, the size and depth of the bore, and the properties of the soil. Depending on the soil being bored as well as the amount of ground loss into the bore, settlement may occur relatively slowly compared to the duration of the project, and measurable settlements may not occur for weeks or months after a bore has been completed. Settlement- sensitive structures such as houses should be identified and settlement tolerances determined. These settlement tolerances should be large enough to be practical to measure, and acceptable limits need to be reasonable to discourage inflated bids. Alternatively, structures could be underpinned to an elevation below the bore or an acceptable remediation plan such as compaction grouting could be developed. Areas of potential settlements should be monitored for a period of one year following construction, and the Contractor should be required to repair any damages that result from exceeding the settlement tolerances during this period. We recommend doing a pre-and post-construction survey of identified sensitive structures. The survey should consist of at least a video and photographic record of the structures and observations by an experienced structural engineer. 7 .1.13 Contractor Qualifications A successful installation of the pipeline, so that it functions as designed, is within tolerance at the required depths and locations, and is constructed on time and within the budget, is attributable in a large part to the experience of the contractor and their field personnel. Therefore, we recommend that the Contractor selection be a two-step process involving prequalification and project bidding. We recommend that only prequalified contractors be invited to submit bids. As such, there should be a defensible, systematic, and quantifiable 2 l-1-20442-001-R I -Rev. doc/wp/LKD 21-1-20442-001 30 , I I SHANNON &WILSON. INC. approach to rating and ranking the submittals to establish prequalification. We have developed prequalification methods that have worked well for other projects and could provide an example should the Owner decide that this approach is desirable. 7.1.14 Construction Submittal In accordance with standard HDD construction practice, it is recommended that the Contractor be responsible for preparing a detailed bore plan. At a minimum, this bore plan should consist of construction procedures, operational sequence, recommended final bore path and size, and the drilling method, in accordance with the final design requirements provided in the specifications and/or on the plans. 8.0 DOCUMENT REVIEW AND CONSTRUCTION OBSERVATIONS We recommend that we be retained to review those portions of the plans and specifications that pertain to construction of the HDD sewer pipe, auger boring, surface anchored sewer pipe, and trenching to determine if they are consistent with our recommendations. In addition, we recommend that Shannon & Wilson be retained to observe construction of these portions of the project and any other field observations pertaining to our geotechnical recommendations and discussions presented in this report. Theodor W. Hopkins, L.E.G. Associate TWH:RJG:/twh 21-1-20442-00 I-RI -Rev.doc/wp/LKD 31 Roberto J. Guardia, P.E. Senior Associate 21-1-20442-001 I SHANNON &WILSON. INC. 9.0 REFERENCES American Society for Testing and Materials (ASTM), 2004, Annual book of standards, Construction, v. 4.08, Soil and rock (I): D 420-D 5779: West Conshohocken, Pa. GEO-SLOPE International, Ltd., 2005, User's guide for SLOPE/W: Calgary, Alberta, Canada. Makdisi, F.I., and Seed, H.B., 1978, Simplified procedure for estimating dam and embankment earthquake-induced deformations: Journal ofGeotechnical Engineering, v. 104, no. GT7, p. 849-867. Maurer Technology, 200 I, Drill Path Planning and Pipe Design Model, Version 2, A computer program for HOD pipe calculations. Washington State Department of Transportation (WSDOT) and American Public Works Association (APWA), 2004, Standard specifications for road, bridge, and municipal construction (M41-10): Washington State Department of Transportation and American Public Works Association. 2 I-1-20442-001-R 1-Rev.doc/wp/LKD 21-1-20442-001 32 ' ~ Q 0 j /ii I 1;i Renton ~ Project Location Scale in Miles NOTE Map adapted from 1 :24,000 USGS topographic map of Renton, WA quadrangle, dated 1949, revised 1994. Central Plateau Interceptor Renton, Washington VICINITY MAP l I June 2006 21-1-20442-001 , ,ii SHAN_NON & WILSON, INC. "-._ ________________________ L..:-::::-:::""'~and~-=·=menta=~'=::"!lta:""~L-!F~IG~.~1~J I ,, I I I I I I I I I I ~ cl: .;I I I I i I I ~ N I it ~ 21 N i I ~ 0 ~ I I ',> ' I ~ ~ ~ lb:~3/}J:~=j;~~:-/ (/'J' rc'~o 1;/ ,;; ) ',,_,r-'"-----l I , !)::_ - I f-, ,.,-) B-1 ~ HB-1 • TP-1 """- ~ Boring Designation and Approximate Location LEGEND --------- Hand Boring Designation and Approximate Location Test Pit Designation and Approximate Location Generalized Subsurface Profile Designation and Approximate Location ,< T" I I • HDD Construction Trench Construction Pipe Auger Construction Surface Mounted Construction Landslide Scar Seepage 0 _L ~~~~~~ 200 400 Scale in Feet NOTES 1. Topography generated from Lidar images available from Puget Sound Lidar Consortium. 2. Property boundaries and locations of structures are based on electronic files provided by Roth Hill Engineers, received 5-19-2005. ( ---j Central Plateau Interceptor Renton, Washington SITE AND EXPLORATION PLAN June 2006 21-1-20442-001 SHANNON & WILSON, INC. 1 FIG 2 Geotechnical and Environmental Consultants • A West 400 350 Manhole B-2 (Proj. 11' NE) I •88 • l,r 64 •56 • 7519 ? !r, 9BtS'-- 02·23-06 8-1 (Proj. 340' NE) r 19 Dense to very dense, sandy GRAVEL (Recessional Outwash) ~ 7 ------I ~r lo,· ? -:>. Existing Ground Surface 24-lnch Dia. Auger Boring Casing _/ with 12-lnch HOPE Sewer Pipe HB-1 (Proj. 38' NE) HS-2 -50/4" · Very dense. slightly silty to silty,'-..::.: ? ? (Proj. 88' NE) gravelly SAND to sandy GRAVEL · (Till-like Deposits) ? In!~-~~-:;: ? ? 300 -50/3" -S.0/3" -50/4' a, (l) Very dense, s~. fine . _ '"' SAND (Outwash) . "' Loose to dense, slightly silty, __} ? ·""-- gravelly SAND (Co/luvium) '-----... lL s ? -----?--- " ?--------- ?-. ?-------- • C 50/3" ' ? er: ~ ~ a .,: w ~ ~ J, 0 ! ~ ~ lg' ~ • .. ~ e "- 9 ~ ~ ;;; C: 0 .. (tJ > (l) [jj 250 200 1£lll 1ml -SQ1s: Hard. silty CLAY to slightly clayey Sil T : ;~ (Nonglacial Lacuslrine Deposits) : 1~[5• Very dense, silty, frne SAND -100/5" (Nonglacia/ Lacuslrine Deposits) -100/5" ? ""50/5' · "100110· Very dense, silty, fine SAND and hard, clayey SILT ?- ""50/4s· --(N I · IL 1 · D ·1 l ?-~,1= ~&'.~-___ ? ong ac1a acus rme epos1 s, ? _ --l' -j ::t'~-=7 -Very dense, silty, sandy GRAVEUgravelly SANO (Outwash) '_J-~00'6' , n:1: BO/~ Very dense, slightly £ j~j: silty to silty SAND 03-10--06 (Outwash) LEGEND B-1---Boring Designation H B • 1 ~-Hand Boring Designation (Proj. ,20' N)----Projected Distance and Direction TP-1 -Test Pit Designation Water Level-Observation Well ~ -... Well Screen , Water Level-VWP --- Standard Penetration Test ::r:: 19 ----Blows/Foot 10 Standard Penetration Test 2 501.i -----8/ows/Jnches Driven I r __ Bottom ofTest Pit ~ 0 . uses Symbol Location of Inferred Seepage I 12-lnch Dia. HDPE Sewer Pipe Alternative_/ ?- 0 50 ~ -=-i::j=--------1 ___L____L__L ----=-1 Scale in Feet Horizontal = Vertical NOTEf, 1. Ground surface profile generated from Lidar images available from Puget Sound Lidar Consortium. .,,,. . . Approxrmate eolog1c Contact , . . g ? . interpreted from shallow hand bonng probes, soils HB-3 (Proj. 73' NE) HB-4 A' East TP-2 (Proj. 191' NE) 400 350 300 250 J200 Loose to medium dense, silty, gravelly SAND (Fill/Alluvium) 150 ----_ ----__ ___J 100 Central Plateau Interceptor Renton, Washington GENERALIZED SUBSURFACE PROFILE A-A' gl lL s C: 0 1 (l) w ~ Vibrating Wire Piezometer (VWP) ~· · ? . G . 2. Subsurface conditions shown along hillside ~ · --Bottom of Boring observed in cut slopes along abandoned dozer road, June 2006 21-1-20442-001 ; 03-10-06 -------------Date completed and extrapolation of soils encountered in Boring 8-1. ~ SHANNON & WILSON. INC. FIG 3 .!!! Geotechnica/ and Environmental Consultants • u::._ _________________________________________________________________________________________________________ .... I I I I I I I I I I I I 0: ~ ~ 0 ~ <( I 8 0 "I N i I .! ffl 0 ~ ! I .; 'I "' g • -" ~ I ! 'I N v v I ~ b 0 I I ~ ~ u: I ~ -a; Ql LL .£ C 0 +' "' > Ql [ij LEGEND B-1 Boring Designation HB-1 ~ Hand Boring Designation B North 400 HB-1 P~38'W)-·· ~"" & i. •... . .(,"<i' Loose to dense, slightly silty, ~'11, gravelly SAND (C-Olluvium) · O,:,'lt. 300 250 HB-2 (Proj. 60' W) Slightly silly to silty; gravelly SAND to sandy GRAVEL (Till-like Deposits/Outwash) HB-3 (Proj. 8'W) &r!A. ~& / Existing Ground Surface HB-4 (Proj. 40' W) TP-2 200 Very dense, silty, fine SAND to hard, slightly clayey SILT or silty CLAY .. J"~ Loose lo med" :s iµm den · gravelly SAND (FIi/Ase, SIity, • ? ' lluv,um) 150 B' South 400 350 300 250 200 150 100 100 -a; Ql LL _£, C 0 i [ij 0 50 50 I El Fl I I {Proj .. 20' N) -----Projected Distance and Direction TP-1--Test Pit Designation ±~ Bottom ofTest Pit Scale in Feet Horizontal = Vertical Water Level-Observation Well ~ Well Screen Filter Pack -- Water Level-VWP --- Standard Penetration Test :i:19 --Blows/Foot = SO/S' ______ Standard Penetration Test Blows/Inches Driven uses symbol Vibrating Wire Piezometer fVWP) --~ 1-iJI ? Approximate Geologic Contact ?--- Bottom of Boring 03-10-06 ----Date Completed ...,.. Location of Inferred Seepage NOTES ~-- 1. Ground surface profile generated from Lidar images available from Puget Sound Lidar Consortium . 2. Subsurface conditions shown along hillside interpreted from shallow hand boring probes, soils observed in cut slopes along abandoned dozer road, and extrapolation of soils encountered in Boring B-1. Central Plateau Interceptor Renton, Washington GENERALIZED SUBSURFACE PROFILE B-B' June 2006 21-1-20442-001 SHANNON & WILSON, INC. I FIG 4 Geotechrucal and Environmental Consultants • 5 C 0 I ~ i I l [ • .. £ ~ I 1, I ., ;,;; , .1!i C West 400 350 300 -Ql Ql u.. .5 C 250 0 "' <ll > Ql iii 200 150 -r ]......... 1 I , I I I I I l I j . t I I . I I I I · . I I I i l;_; ... t I (Pfoj. 22' N) silty, gravelly I I SAN (Fill) . . ....... j I . i .. . . . . I . ~? I \_ Dense,"'~. , Man~ole ,_ I gravelly D · (Alluvium, i 1 Hard, dayey SILT (No/,glacial Lacustrine Deposits) 8-31 (Proj. 21' N) ~ :cS8JW =!j(J/5" -i-~56th Ave SE Manhole -----'---Loose to very deJse, sandy GRAVEL (Recessional Outwash) = J:'. Very dense, sil,ly, fine SAND 02-23--06 (Nonglacial Lacustrine Deposits) C' East -----400 350 300 250 -~200 150 -Ql Ql u.. .5 C 0 !ii > ~ w 100 I i 100 LEGEND 8-1 -Boring Designation HB-1 ~ Hand Boling Designation (Proj. ,20' N) ~ Projected Distance and Direction Water Level-Observation Well '---... Standard Penetration Test :c 19 -Blows/Foot Well Screen Filter Pack -----'f~-l= 50/5" ~ Standard Penetration Test Blowsnnches Driven Water Level-VWP -uses Symbol Vibrating Wire Piezometer (VWP) ----L..J t·e ? Approximate Geologic Contact /1 . ? ---Bottom of Boring 03-10-06 --Date Completed TP-1 ~ Test Pit Designation i_ Bottom of Test Pit ~ Location of Inferred Seepage 0 t:a 50 Fl f Scale in Feet Horizontal = Vertical NOTES 50 j 1. Ground surface profile generated from Lidar images available from Puget Sound Lidar Consortium. 2. Subsurface conditions shown generalized from materials encountered in Boring B-3 and observed in soil exposure southeast of boring. Central Plateau Interceptor Renton, Washington GENERALIZED SUBSURFACE PROFILE C-C' June 2006 21-1-20442-001 SHANNON & WILSON, INC. J FIG 5 Geotechnlcal and Environmental Consultants • u:....._ __________________________ _J_~~~=...1~::.:....J .. i • l I I ' ' I ' II I II .... z I (.) C I II i!l 0 :J: $ I .!l i'l ll' ~ I io I <O ~ I 0 9 ~ g N I ' ;;; D ij N ... I g N D ~ ;;; D '-, I ,i! u. -- Flow / Galvanized Steel Anchor Post or Chance Anchor Transition from Below Grade to At-Grade ~ 3/8" Diameter ~ :/ Galvanized ~ Steel Cables ol---~.ro 2-Piece Band Clamp Below Each Joint and Every 20 Feet _ 12-ln._ Min. Dia. :_,,,--Pipe Joint C[(Q) L-----.J.__Q l Flow TYPICAL PLAN VIEW Notto Scale Central Plateau Interceptor Renton, Washington TYPICAL PIPELINE ANCHORING DETAILS June 2006 21-1-20442-001 SHANNON & WILSON, INC. I FIG. 6 -ond Enwonment,I Conou11an1s Sheet 1 of 2 ----------------File: J:D211020442.Q01021•1 4 20442-001 Fig 6 (06-06).dwg Date: 06.09·2006 Author: CNT "'"Tl i_ !.Ci) "'. 2.cn "' ~ NOTES 1. Place anchors below each pipe joint and not more than 20 feet apart. 2. Design ground anchors for the anticipated axial load, but not less than 5,000 lb. 3. Contractor may propose an alternate anchor system for approval by the engineer. HOPE Pipe 12-ln. Diameter Ground Surface 20-Ft. Max. _______--\ (TYP.) Chance Chain Shackle 3/8-ln. Diameter Galvanized Steel Cable Band Clamp (TYP.) TYPICAL CROSS SECTION Not to Scale Chance Anchor (TYP.) Central Plateau Interceptor Renton, Washington TYPICAL PIPELINE ANCHORING DETAILS June 2006 21-1-20442-001 SHANNON & WILSON, INC. i FIG. 6 Geotechnlcal and EnvllQl'IITMll'ltal eon.un.ntt Sheet 2 of 2 I I I I I I I I I I 'I -~ Ii If ,~ i I ~ ;;; Existing Ground Surface .-- Subsequent Backfill / // I Initial Backfill I j Granular Bedding (See text) Restored Surface l I It Trench Excavation Slopes r----' and/or Temporary Support Systems are the Conlracto(s Responsibility t •---Do -----1 i•tt-Excavation Subgrade Not to Scale NOTES 1. Granular bedding and initial backfill material should meet the requirements of WSDOT Section 9-03.12(3 ). Gravel backfill for pipe zone bedding. 2. Subsequent backfill should consist of select trench excavation material or imported granular material that meets the requirements (WSDOT/APWA 9-03-10). ll Central Plateau Interceptor Renton, Washington TYPICAL PIPE TRENCH SECTION EXCAVATING IN DRY ,1 · June 2006 21-1-20442-001 ~ Bank run gravel for trench backfill. ~ ~L.~~~~~~~~~~~~~~~~~~~~~~_j_!~~,~="~'-~J!!0:~!8~~~-'!':m•:\!:.5:~!o"""""""'"~N=,~IN=C~ . .J~-F::.!:IG:=:.,.:7~J APPENDIX A SUBSURFACE EXPLORATIONS SHANNON &WILSON, INC. 21-1-20442-001 APPENDIX A SUBSURFACE EXPLORATIONS TABLE OF CONTENTS SHANNON t,WILSON, INC. Page A.I INTRODUCTION ........................................................................................................... A-1 A.2 SOIL CLASSIFICATION ............................................................................................... A-1 A.3 DRILLING PROCEDURES ........................................................................................... A-1 A.4 SOIL SAMPLING AND HANDLING ........................................................................... A-2 A.5 TEST PITS ....................................................................................................................... A-3 A.6 GROUNDWATER .......................................................................................................... A-3 A.6.1 Monitoring Well Installation and Construction ................................................ A-3 A.6.2 Vibrating Wire Piezometer (VWP) Installation ................................................ A-4 A.6.3 Well Development.. ........................................................................................... A-4 A.6.4 Groundwater Sampling ..................................................................................... A-4 A.7 REFERENCE .................................................................................................................. A-5 TABLE Table No. A-I Summary of Borings, Wells, and Groundwater Levels 21-1-20442-001-RI-ANwp/EET 21-1-20442-001 A-i TABLE OF CONTENTS (cont.) SHANNON &WILSON, INC. LIST OF FIGURES Figure No. A-1 Soil Classification and Log Key (2 sheets) A-2 Log of Boring B-1 (4 sheets) A-3 Log of Boring B-2 A-4 Log of Boring B-3 (2 sheets) A-5 Log of Hand BoringHB-1 A-6 Log of Hand Boring HB-2 A-7 LogofHand BoringHB-3 A-8 Log of Hand Boring HB-4 A-9 Log of Test Pit TP-1 A-10 Log of Test Pit TP-2 21-l-20442..001-Rl-AA/wp/EET 21-1-20442-001 A-ii A.1 INTRODUCTION APPENDIX A SUBSURFACE EXPLORATIONS SHANNON &WILSON. INC. This appendix provides descriptions of the standard field methods used by Shannon & Wilson, Inc. in performing the subsurface investigations discussed in this geotechnical report. The subsurface exploration program for the Central Plateau Interceptor project included drilling and sampling three soil borings, four hand borings, and two test pits. The approximate exploration locations are shown in the Site and Exploration Plan (Figure 2) in the main text of the report. Elevations shown in the boring and test pit logs were estimated by plotting the exploration locations on a topographic plan provided by Roth Hill Engineering Partners, LLC, and are approximate. Boring B-2 was backfilled upon completion, and monitoring wells were installed in borings B-1 and B-3, with a vibrating wire piezometer (VWP) installed in B-1. Boring, well, and water level data are provided on Table A-1 of this appendix. A.2 SOIL CLASSIFICATION An experienced geologist from Shannon & Wilson, Inc. was present throughout the current subsurface exploration to observe the drilling and sampling operations, retrieve representative soil samples for subsequent laboratory testing, and to prepare descriptive field logs of the explorations. Soils were classified in general accordance with the American Society for Testing and Materials (ASTM) Designation: D 2488-93, Standard Recommended Practice for Description of Soils (Visual-Manual Procedure). The Unified Soil Classification System (USCS), as described in Figure A-1, was used to classify the soils encountered in the explorations. The boring and test pit logs in this appendix represent our interpretation of the contents of the field logs. A.3 DRILLING PROCEDURES Borings B-1 and B-3 were performed using mud rotary drilling methods. Boring B-1, in which a monitoring well and VWP were installed, was drilled to a total depth of 185.5 feet. Boring B-1 was accomplished in two parts by Holocene Drilling using a CME 850 track-mounted drill rig equipped with 2.9-inch outside-diameter (O.D.) drill rods, and a 7-inch O.D. bit. The first part of 21-1-20442-00l-RI-ANwp/EET 21-1-20442-001 A-1 SHANNON &WILSON. INC. drilling was accomplished January 13 to 17, 2006, and was discontinued after reaching a depth of94 feet because of heavy rains and coincident landslides, which occurred within a mile of the project area. The remaining drilling and well installation of boring 8-1 were performed March 7 to 13, 2006. Boring 8-3 was drilled to a depth of 118.4 feet and was performed February 21 to 23, 2006, by Holocene Drilling using a Mobile 8-61 truck rig equipped with 2.9-inch O.D. drill rods, and a 7-inch-diameter bit. Boring 8-2 was drilled to a depth of 31.3 feet and was performed February 23, 2006, using hollow-stem auger drilling methods by Holocene Drilling using a Mobile 8-59 truck rig equipped with 5-foot-long, 4.25-inch inside-diameter (I.D.), 9-inch 0.D. auger flights, 5-foot- long, 1.75-inch I.D. drill rods, and a JO-inch O.D. bit. A two-person crew from Shannon & Wilson, Inc. performed hand borings HB-1 through HB-4 using portable, hand-operated equipment. The depths of these hand borings ranged from 7.5 feet to 10.5 feet. With the exception ofHB-3, the removal ofdownhole equipment (hand auger or split-spoon sampler) invariably led to caving of the hole, which was due to the gravelly nature of the colluvium mantling much of the hillslope. Thus, the hand borings were advanced by continuously driving the sampler into the subsurface. The hand borings were therefore used more as probes to evaluate the thickness of less dense colluvium overlying very dense soils, rather than as borings to obtain subsurface soil samples. The hand borings were terminated when it became very difficult to extract the sampler from the hole. A.4 SOIL SAMPLING AND HANDLING Soil samples from the borings were collected using the Standard Penetration Test (SPT). SPTs were performed in general accordance with ASTM Designation: D 1686, Standard Method for Penetration Testing and Split-Barrel Sampling of Soils. SPTs were performed at 5-foot intervals in all three borings, with a 2-inch O.D. split-spoon sampler for B-1 and B-3, and a 3-inch O.D. split-spoon sampler for B-2, using a 140-pound automatic hammer and a 30-inch drop. The SPT consists of driving the sampler with repeated hammer blows a distance of 18 inches into the bottom of the borehole. The number of blows required for the last 12 inches of penetration is termed the Standard Penetration Resistance (N-value). The N-value is an empirical parameter that provides a means of determining relative soil density. Relevant information, including SPT N-values and drilling action, are shown on the boring logs. Soil cuttings and drilling mud were contained in 55-gallon drums and hauled off site by the driller for disposal. 21-1-20442--001-R 1-AA/wp/EET 21-1-20442-001 A-2 SHANNON &WILSON. INC. The relative density of soils encountered in hand borings H8-l through HB-4 was determined using the Porter Penetration Test (PPT), which is a modification of the SPT. The PPT involves driving a 1.5-inch O.D. split-spoon sampler a distance of 18 inches into the bottom of the boring with repeated blows of a 40-pound hammer falling 18 inches. The number of blows required to drive the sampler for each of the last two 6-inch increments are approximately equivalent to an SPT N-value. Due to caving of the hole described above, the hand borings were advanced using a modified PPT, in that PPT N-values were recorded for each 6-inch increment while continuously driving the sampler. A.5 TEST PITS Test pits TP-1 and TP-2 were excavated January 6, 2006, using a rubber-tired backhoe with an extendable arm and toothed backhoe bucket. The test pits were excavated into the soil approximately 12 feet, near the maximum reach of the backhoe. Soil density in the test pits was estimated based on probing shallow sections of the excavation walls, and from the relative ease or difficulty of backhoe excavation. Test pit soil samples were collected either directly from the backhoe bucket teeth or from spoils adjacent to the test pit immediately following excavation from a particular depth interval. Locations of soil samples, groundwater seepage, and other subsurface features are depicted on the test pit logs in this appendix. Upon completion of sampling and logging, the Contractor backfilled the test pit excavations with spoils and tamped the area with the backhoe bucket. A.6 GROUNDWATER The following subsections describe monitoring well and VWP installation, well development, and groundwater sampling. Groundwater levels and well information are summarized on Table A-1 of this appendix. A.6.1 Monitoring Well Installation and Construction Monitoring wells were installed in borings 8-1 and 8-3 after the borings were advanced to total depth and partially backfilled to the desired well bottom depths. The wells were constructed using new, commercially fabricated, threaded, flush-jointed, 2-inch-diameter, Schedule 40 polyvinyl chloride (PVC) screen and riser. Well screens consisted of0.01-inch- wide, machine-slotted PVC, with 10-and 15-foot screened intervals for B-1 and 8-3, respectively. The top of each well was completed with a 2-inch expandable locking cap, and 21-I-20442-001-RI-AA/wp!EET 21-1-20442-001 A-3 SHANNON &WILSON, INC. threaded sumps were installed at the bottom of each well. Following installation of the casing and screen in each well, a silica sand filter pack was poured into the annular space between the boring wall and the well screen to about 2 to 3 feet above the top of the screen. The remaining annulus was filled with bentonite chips to within 2 feet of the ground surface. Well B-3, which is on the street about I foot inside the west curb of 156'h Avenue SE, was completed flush to grade by cementing an 8-inch flush-mounted steel monument over the top of the borehole. Well B-1, which is located on undeveloped land, was completed about 3 feet above grade by cementing a 6-inch-diameter steel monument, its cap secured with a padlock, over the top of the borehole. Screened interval depths are shown in the boring logs and Table A-1 in this appendix. A.6.2 Vibrating Wire Piezometcr (VWP) Installation One VWP was installed near the bottom of B-1, at 177 .5 feet below grade, to evaluate deep groundwater conditions that may be encountered during pipeline construction. The VWP was calibrated and hung to its target depth before the observation well was installed above it, and surrounded with filter pack to at least 3 feet above the VWP sensor tip. The annular space was filled with bentonite chips between the top of the VWP sand filter pack and the bottom of the observation well sand filter pack. VWP depth and depth intervals of backfill are shown on the boring log for B-1 and on Table A-1 in this appendix. A.6.3 Well Development Well development was performed at observation well B-1 to improve the hydraulic connection between the aquifer and the screened portion of the observation well. The saturated screened section of the observation well was surged and pumped simultaneously to remove water and sediment from the bottom of the well, so that subsequent sampling from the well would produce a groundwater sample representative of the aquifer. Development equipment consisted ofa Waterra™ acetal surge block/check-valve combination attached to the bottom ofa dedicated section of semi-rigid, high-density polyethylene (HDPE) tubing, operated by an electric Waterra™ motor. The B-1 observation well was pumped until there was no further observed improvement in water clarity. A.6.4 Groundwater Sampling The B-1 observation well was sampled at least 24 hours after being developed with the same dedicated tubing used for development, with a new, stainless steel surge block/check valve. 21-1-20442-001-Rl-AA/wp/EET 21-1-20442-001 A-4 SHANNON &WILSON. INC. A minimum of three well volumes was removed from the well, and the observation of water quality parameter stabilization (pH, temperature, oxidation-reduction potential, conductivity, dissolved oxygen, turbidity, salinity, total dissolved solids, and water clarity) was met prior to groundwater sampling. A.7 REFERENCE American Society for Testing and Materials (ASTM), 2002, Annual Book of Standards, Construction, v. 4.08, Soil and Rock (I): D 420 -D 4919: West Conshohocken, Pa. 21-1-20442-001-RI -AA/wp/EET 21-1-20442-00 I A-5 TABLEA-1 SUMMARY OF BORINGS, WELLS, AND GROUNDWATER LEVELS B-1 I 3/1312006 I MR I 185.5 B-2 2123/2006 HSA 31.3 B-3 2123/2006 MR 118.4 Notes: * Groundwater level inferred from sample moisture during drilling Elevations are in feet (NAVO 88) ft bgs = feet below ground swface HSA = Hollow-Stem Auger MR= Mud Rotary NA= No well or VWP installed in boring OW= Observation Well VWP = Vibrating Wire Piezometer 2I•l-20442-001-RI-Tbl-A-I /wp/cdb I 76 to 86 I 268.5 to 278.5 I 177.5 I 3/1512006 71.4 3120/2006 75.7 415/2006 76.0 NA NA NA NA 29.0* 43.5 to 58.5 291.5 to 306.5 NA 3/15/2006 28.8 3120/2006 29.0 4/512006 29.9 283.6 279.3 279.0 328.0· 321.2 321.0 320.1 SHANNON & WILSON, INC. 165.9 166.1 166.2 NA NA NA NA 189.1 188.9 188.8 NA NA NA NA 21-1-20442-001 N COARSE- GRAINED SOILS (more than 50% retained on No. 200 sieve) . FINE-GRAINED SOILS (50% or more passes the No. 200 s;eve) HIGHLY· ORGANIC SOILS ul\llFll:9.so1L cLASSIF!CATIPN SY$TEM (U~CS) . (from ASTM D 2487-98 & 248S.:93) . . .. . '' ,:,; ·. MAJOR DIVISIONS Gravels (more than 50% of coarse fraction retained on No. 4 sieve) Sands Clean Gravels (less than 5% fines) Gravels with Fines (more than 12% fines) Clean Sands (fess than 5% fines) GROUP/GRAPHIC SYMBOL GW GP GM GC SW SP ·--..... '· , .... --~u ,(y o D c:_ • '/ .. .. .. TYPICAL DESCRIPTION Well-graded gravels, gravels, gravel/sand mixtures, little or no fines. Poorly graded gravels, gravel-sand mixtures, little or no fines Silty gravels, gravel-sand-silt mixtures Cl_ayey gravels, gravel-sand-clay mixtures Well-graded sands, gravelly sands, little or no fines Poorly graded sand, gravelly sands, little or no fines {50% or more of 1------4----1'··,.· ;,;"· .. ··.·+'i'l"l---------------1 coarse fraction -... passes the No. 4 sieve) Sands with Fines (more than 12% fines) Inorganic SM SC ML CL .. -_.; .. ,••. ,•. .. -... · ... Silty sands, sand-silt mixtures Clayey sands. sand-clay mixtures Inorganic silts of low to medium plasticity, rock !lour, sandy silts, gravelly silts, or clayey silfs with slight iilasticilv Silts and Clays (liquid lim;t less than 50) - Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays.lean clays f------------1--~-------t Organic OL ~ -- ~ -- f--- Organic silts and organic silty clays of low plasticity Silts and Clays Inorganic (liquid limit 50 or CH Inorganic silts, micaceous or diatomaceous fine sands or silty soils, elastic silt Inorganic cla~ or medium to high plasticity, sandy fat clay, or gravelly fat clay MHI more) f-------+---ff ///'/ -----I / Organic clays of medium to high '/ ' plasticity, organic silts // Organic OH Primarily organic matter, dark in color, and organic odor PT Peat, humus, swamp soils with h~ organic content {see ASTM D 44 ) NOTE: No. 4 size= 5 mm; No. 200 size= 0.075 mm 1. Dual symbols (symbols separated by a hyphen, i.e., SP-SM, slightly silty fine SAND) are used for soils with between 5% and 12% fines or when the liquid limit and plasticity index values plot in the CL-ML area of the plasticity chart. Central Plateau Interceptor Renton, Washington SOIL CLASSIFICATION AND LOG KEY ~ 2. Borderline symbols (symbols separated by a slash, i.e., CUML, silty June 2006 21-1-20442-001 u CLAY/clayey SILT; GIM'SW. sandy GRAVEUgravel/y SAND) ~ indicate that the soil may fall into one of two possible basic groups. SHANNON & WILSON, INC. FIG. A-1 ii Geotechnieal and Environmental Consultants Sheet 2 of 2 ai;L----------------------....1._ __________ _. __ ===--' ~ @ Total Depth: 185.5 ff. Northing: Top Elevation: -355 ff. Easting: Vert. Datum: NAVD88 Station: Horiz. Datum; Offset: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and dn1/ing methods. The stratification lines indicated below represent the approximate boundaries between material t;,pes, and the transition may be gradual. Medium dense, gray, silty, sandy, fine to coarse GRAVEL; wet; scattered, irregular orange iron-oxide staining; (Qvro) GM. Dense to very dense, brown to gray-brown, sandy GRAVEL, trace of silt, to slightly silty, sandy GRAVEL; moist to wet; with layers of silty, gravelly SAND, scattered iron-oxide staining above 22 feet. scattered to abundant cobbles inferred from drill action; (Recessional Outwash) GW/GW-GM. Drilling Method: Mud Rotary Drilling Company: Holocene Drilling Drill Rig Equipment: ~C~M~E~8~50~---- 0ther Comments: Hole Diam.: 7 in. Rod Type: NWJ Hammer Type: _~A~u~to~m~a~•~·c~ 0 "' a, .0 a. E .c 1i " ~ C: a, ::,- 0"' "" t PENETRATION RESISTANCE (blows/foot) .& Hammer Wt. & Drop: 140/bs/30inches OJ 0 4.0 >, (/) i ·• E (9 s "' a, Cl) 0 ,. ,I ,I ,I •I ,I 1-~V~e_ry_d_e_n_s_e_, _g_ra_y~-b-r-ow_n_, s~l~ig~h-ty-s~il~ty_t_o_s~il~ty-, ---, 37 ·0 gravelly SAND to sandy GRAVEL; moist; (Till-like Deposit) SP-SM/SM. 9= 10= 11= 12= ~ CONTINUED NEXT SHEET 1------"'"'-"'"'="=c.ee!ss.,_ ___ _J_ _ _L:_lll._.....L. Sample Not Recovered I Standard Penetration Test LEGEND NOTES [EJ Piezometer Screen and Sard Filter ~ Bentonite-Cement Grout ~ Bentonite Chips/Pellets 0J2J Bentonite Grout 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. Cl 2. Groundwater level, if indicated above. is for the date specified and may vary. 0 ..., 3. uses designation is based on visual-manual classification and selected lab testing. 0 20 0 % Fines {<0.075mm) • % Water Content Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-1 June 2006 21-1-20442-001 ~ 4. The hole kxation was measured using a cloth tape from existing site features and SHANNON & WILSON, INC. FIG. A•2 ~'--·'·hould--be-co•n•s;_d•.red __ •w_ro_~_ma_••_· ________________ .,__-__ ""_"..,_'.""-"".".'°"-""""-'.' =--"-"'.".b_...__s;.hee.;.;.;.t;.1;.of .... 4 _ _, I Total Depth: 185.5 ft. Northing: Drilling Method: Mud Rotary Hole Diam.: 7 in. Top Elevation: -355 ff. Easting: Drilling Company: Holocene Dri!Hng Rod Type: NWJ Vert. Datum: NAVD88 Horiz. Datum: Station: Offset: Drill Rig Equipment: ~C~M~E~8~5~0~---- 0ther Comments: Hammer Type: _~A~u~to~m~a~t~ic~ ~ lil SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. "" .c a. Q) 0 0 "' .!!l .c a. E E >, "' rn rn Very dense, red-brown becoming brown with depth, silty, fine SAND; moist to wet; heavy iron-oxide staining at top and decreasing with depth, layers of slightly silty sand; (Outwash) SM. 62.5 .. :·. ,,I Hard, gray to lavender-gray, silty CLAY grading to slightly fine sandy, slightly clayey SILT with depth; moist; bedded; (Nonglacial Lacustrine Deposit) CL/ML. 86.0 l---c-V~e-ry-d7 e_n_s_e_, -re-d,-,-b,_r_o_w_n_, s-cicclty-,--cfi~,n-e--cS:-A:-:NccD=c-; m-o7is7t---, 93 ·5 to wet; laminated to bedded; iron-oxide stained to depth of 123 feet; scattered seams of gray, slightly clayey silt to fine sandy silt; trace of gravel locally; (Nonglacial Lacustrine Deposit) SM/ML. isI i lJ !J 16::C t-.j: 11::r:: ,.I . : .. 20::r::: "1' :; i •• •• l:: c': 21= r1 ,. ,1 ·. f-1: ·, 22::I: ,l < . : .. 23:::C: : ·. 24::I: § ~ 0 ~ .§' CONTINUED NEXT SHEET 1--------======-'--------'----"L.'1'----'-- I ij ~ ~ ~ ~ !~· Sample Not Recovered I Standard Penetration Test = [BJ Piezometer Screen and Sand Filter ~ Bentonite--Cement Grout ~ Bentonite Chips/Pellets ~ Bentonite Grout NOTES N 1. Refer to KEY fof explanation of symbols, codes. abbreviations and definitions. w ci 2. Groundwater level, if indicated above, is for the date specified and may vary. g 3. uses designation is based on visual-manual classification and selected lab testing. "" ~ C: " :, -0"' (9 ;;-: "" PENETRATION RESISTANCE (blows/foot) f .ol. Hammer Wt. & Drop: 140/bs/30inches " 0 60 ·: ·: ·: · : .. : · 5015' 50/6" 100/6" 40 0 % Fines (<0.075mm) • % Water Content Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-1 60 June 2006 21-1-20442-001 " ~ 4. The ho~ location was measured using a cloth tape from existing site features and SHANNON & WILSON, INC. FIG, A•2 ~ should be considered approximate. Geotec:hnical and Environmental Consultants Sheet 2 of 4 ,,._ ____________________________ ._ ____________________ .. I Total Depth: 185.5 ft. Northing: Top Elevation: -355 ft. Easting: Vert. Datum: NAVD88 Station: Horiz. Datum: Offset: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between maten·a1 rypes, and the transition may be gradual. -Brown below 123 feet. Very dense, red-brown and gray-brown, silty, fine SAND to SILT, trace of clay and fine sand; moist; laminated to bedded iron-0xide-stained seams; (Nonglacial Lacustrine Deposit) SM/ML. Very dense, gray to purple-gray, silty, fine SAND, trace of clay; moist; 1-inch-thick clay layer; (Nonglacial Lacustrine Deposit) SM/CL. Hard, gray to purple-gray, slightly clayey SILT, trace of fine sand to very dense, clayey, silty, fine SAND; moist to wet; bedded, scattered organic-rich seams; (Nonglacial Lacustrine Deposit) MUSM. Very dense, intemiingled, gray and red-brown, I clayey, silty, fine SAND to fine sandy, clayey SILT; moist to wet; irregular iron-oxide staining; SM/ML. Very dense, gray and brown, silty, sandy GRAVEL and silty, gravelly, fine to coarse SAND; moist to wet; (Outwash) GM/SM. Drilling Method: Mud Rotary Drilling Company: Holocene Drilling Drill Rig Equipment: ~C~M~E~8~50~---- 0ther Comments: Hole Diam.: 7 in. Rod Type: NWJ Hammer Type: _~A~u~to~m~a~t~ic~ "' .c: n. 0 .a E >, Cl) "' ~ a. E PENETRATION RESISTANCE (blows/foot) £ A Hammer Wt. & Drop: 140 lbs I 30 inches a. Q) 0 "' Cl) . : :: 25:::::r::: 142.0 . : 29 ::r:: 145.0. 150.0. ·: .:.31I 156.0 · .. I I°' ' 166.0 _i_ .• ·. 34:::C Q) 0 20 40 60 100/4.5" NOTE: Sampler and drill string dropped from t.': 163 to 166 feet; interpreted as a void. , . . Very dense, brown and gray, silty, fine to i·:: ,·: 35= medium SAND grading with depth to gray, [:: , : ~ slightly silty, fine to coarse SAND; wet; i:: . : 36 = ~ scattered beddina. locallv trace of fine gravel; 1f. __ ._ : ·.. "'~ -1--------'lX>""'NT!!.lc,N~UEe,D,_,N,sEXT""-Se,H,sEe;ET.,_ ____ __l. __ l±.L:il _ _JLJ"'---_L--J..,c-'-'-'--'--f,---'---'--'-'-.C...C.-'-,l,-'--'--''-'--'--'-~ 0 20 40 60 w Sample Not Recovered I Standard Penetration Test = NOTES [HJ Piezometer Screen and Sand Filter ~ Bentonite-Cement Grout ~ Bentonite Chips/Pellels ~ Bentonite Grout 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. 0 % Fines (<0.07Smm) • % Water Content Plastic Limit I e I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-1 June 2006 21-1-20442-001 ffi 4. The hole k>cation was measured using a cloth tape from e,isUng site fealoces and SHANNON & WILSON, INC. FIG. A•2 i._ __ '_hou_k:l_be_cons_,_dered __ '_PP_"'_'_'m_•_••_. _______________ ,__Geot __ """_""'_._,_""'_E_=_·_mem_,_,eons __ ""-"'_"_.._ __ s.,heet .... ..,J..,of_4;...- Total Depth: 185.5 ft. Northing: Drilling Method: Mud Rotary Hole Diam.: 7 in. Top Elevation: -355 ft. Easting: Drilling Company: Holocene Drilling Rod Type: NWJ Vert. Datum: NAVD88 Horiz. Datum: Station: Offset: Drill Rig Equipment: ~C~M~E~85(J=----- Other Comments: Hammer Type: _~A~u~lom=•~l,,ic'---- SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between matedal t'jpes, and the transition may be gradual. (Outwash) SM/SP-SM. BOTTOM OF BORING COMPLETED 3/10/2006 ~ "' .c a. " 0 185.5. 0 U) " .0 C. E E >, "' Cf) Cf) , .: 37::I: . 38= Sample Not Recovered I Standard Penetration Test [BJ Piezometer Screen and Sand Riter ~ Bentonite-Cement Grout ~ Bentonrte Chips/Pellets ~ Bentonile Grout NOTES 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. ,, ~ "' C 0) ,= ::,- 0"' a. (9 Os: " 0 ~~ :y-~ ~~ '"' PENETRATION RESISTANCE (blows/foot) ... Hammer Wt. & Drop: 140 lbs I 30 inches 0 % Fines (<0.07Smm) • % Water Content Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-1 2. Grouncf\.vater level, if indicated above. Is for the date specified and may vary. 8 June 2006 21-1-20442-001 ..J 3. USCS designation is based on visual-manual classification and selected lab testing. ffi 4. The ho~ location was measured using a cloth tape from existing site features and SHANNON & WILSON, INC. FIG. A-2 ~L--'-"°"_kl_be_co_n_si.de.red_•_P~-'o.xi•ma•t~~----------------L--------------,._..;;;;;;;;.;.;;;..;..._,1 :;: Geotechnical and Enwonmental Consultants Sheet 4 of 4 @ Total Depth: 31.3 ft. Northing: Top Elevation: -357 ft. Easting: Vert. Datum: NAVD88 Station: Horiz. Datum: Offset: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated befow represent the approximate boundaries between material types, and the transition may be gradual. ASPHALT. Medium dense, brown, slightly silty to silty, gravelly, fine to coarse SAND; moist; scattered organics and rootlets; (Recessional Outwash) SM/SW-SM. Very dense, brown to gray, fine to coarse sandy GRAVEL, trace of silt; moist; with layers of gray sand, scattered to abundant cobbles inferred from drill action and spoils; (Recessional Outwash) GW. Drilling Method: Hollow Stem Auger Drilling Company: Holocene Ori/Jing Drill Rig Equipment: --"M,,oc,becilee..,,B'-'-5"'9'---~ Other Comments: Hole Diam.: 10 in. Rod Type: Hammer Type: _,eA,,,uo,ta,,.me,ae,t,,ic'-- "" 0 "' " £ .D C. E E -0 C: " ::, - 0 "' "" JC 0. PENETRATION RESISTANCE (blows/foot) A Hammer Wt. & Drop: 1401bs/30inches 0. " >, "' 0 en en (9 ~ " 0 0 60 20 40 1-----------------------30.0 Very dense, gray, silty, gravelly, fine to coarse SAND; wet; scattered seams of fine to medium 31 ·3 sand; (Till-like DeposiURecessional Outwash) SM. BOTIOM OF BORING COMPLETED 2/23/2006 11-___________ __J_ _ __j_J___J_ ___ ..L_--'-_ __J__-'--'-'.--'..L.c--'--'-'--'-'-'-'-I ~ ~ " ~ " w " g ~ t; ~ LEGEND Sample Not Recovered ]I[ 3~ 0.D. Split Spoon Sample NOTES 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. uses designation is based on visual-manual classificaUon and selected lab testing. 4. The hole location v-as measured using a cloth tape from existing site features and should be considered approximate. 0 % Fines (<0.075mm) • % Water Content Plastic Limit I e I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-2 June 2006 21-1-20442-001 SHANNON & WILSON, INC. FIG A 3 Geoiechnical and Environmental Consultants • • >'L.. _____________________ _,_ __________ _,_ ____ ---1 Total Depth: 118.4 ft. Northing: Top Elevation: -350 ft. Easting: Drilling Method: Drilling Company: Holocene Drilling Mud Rotary Hole Diam.: 7 In. Rod Type: NWJ Vert. Datum: NAVDBB Horiz. Datum: Station: Offset: Drill Rig Equipment: Mobile B-61 Other Comments: Hammer Type: _~A=u~lom~a=li=c- SOIL DESCRIPTION Refer ro the repo,1 text for a proper understanding of the subsurface materials and drifling meU1ods. The stratification Jines indicated below represent the approximate boondaries between material types, and the transition may be gradual Asphalt. Loose to very dense. gray-brown, sandy GRAVEL, trace of silt. to orange-brown and gray, slightly silty, sandy GRAVEL; moist to wet below 28 feet; with layers of slightly silty, gravelly sand; abundant faint orange iron-oxide staining; (Recessional Outwash) GW/SP-SM. "' .c Q_ " 0 1--D-e-n-se-.-g-ra_y_,_s_lig_h_t_ly_s_il~ty-.-s-lig_h_t_ly_g_r_a-ve~l~ly_t_o_------j 30 ·0 gravelly SAND; wet; (Recessional Outwash) SP-SM. 1--V-e_ry_d_e_n_s_e_, g_r_a_y_, g-r-a-ve-1-ly-, -s-ilt_y_S_A_N_D-to-----J 38 ·0 gravelly, sandy SILT, trace of clay; moist to wet; (Till-like Deposit) SM/ML. 0 "' d) .0 a. E E >, "' {/) {/) 1--------------------J 47.5 .... 10:::r:: Very dense, gray, silty, gravelly SAND; moist to wet; scattered layers of silty, sandy gravel, scattered cobbles inferred from drill action (Till-like Deposit) SM/GM. ool------~b~-------1~.--------j 75.0 fil Very dense, red-rown to gray-brown, s 1ghtly j silty, sandy GRA~t.lrt~~eir~~lb)\~fND; moist; = :::·:11= ·:: :: 12= . : : 13:::C ·. '. ; ': 14::C: ·:::·:1s= Sample Not Recovered I Standard Penetration Test [BJ Piezometer Screen and Sand Filter i 8 ~ ~ z < is ~ N i.· NOTES ~ Bentonite-Cement Grout ~ Bentonite Chips/Pellets ~ Bentonite Grout N 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. w c;i 2. Groundv,Jater level, if indicated above, is for the date specified and may vary. g 3. USCS designation is based on visuaknanual classification and selected lab testirg. ¢i PENETRATION RESISTANCE (blows/foot) £ A Hammer Wt. & Drop: 1401bs/30inches C. Q) 0 40 0 % Fines (<0.075mm) • % Water Content Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-3 June 2006 21-1-20442-001 60 ~ ~ 4. The ho~ bcaUon was measured u~ng a cloth tape from e,isting site features and SHANNON & WILSON, INC. FIG. A-4 ~'---s-hou_~_be_cons-id_er_ed_a_pp_ro_x_ima-te_. _______________ 1,.._""°' __ ""'_"°"_._'°"_•_.,._.""'_"""_'"t-eon, __ """"-"-.i......;S;;;h,;;ee;;.t.;.1,;;of;.;2;...,._1 Total Depth: 118.4 ft. Northing: Drilling Method: Mud Rotary Hole Diam.: 7 in. Top Elevation: -350 ft. Easting: Drilling Company: Holocene Drilling Rod Type: NWJ Vert. Datum: NAVD88 Station: Drill Rig Equipment: ~M~o~b,~l•~B-~6~1 ___ _ Hammer Type: -~A~u~to~m=at~ic'-- w Horiz. Datum: Offset: SOIL DESCRIPTION Refer to the reporl text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. iron-oxide stained; (Outwash/Nonglacial Fluvial Deposit) SW-SM/GW-GM. Other Comments: 0 .0 E >, CJ) :: :I "' a, 0. E "' CJ) i--~~-~--~--~~-~=~---195.0 Hard, red-brown, fine sandy, clayey SILT; moist to wet; heavy iron-oxide staining, interbedded with sand at bottom; (Nonglacial Lacustrine Deposit) ML/SM. Very dense, red-brown, silty, fine SAND; moist; seams of gray-brown, fine sandy, clayey silt at 107.5 and 112.5 feet; (Nonglacial Lacustrine Deposit) SM. 98.0 ... , 20:::r:: ; : 22::::C :'. 23I 1-------------------------1118.4 .. ·. 24I BOTTOM OF BORING COMPLETED 2/23/2006 ill,EW Sample Not Recovered I Standard Penetration Test = [BJ Piezometer Screen and Sand Filter ~ Bentonite-Cement Grout ~ Bentonite Chips/Pellets 0JJ Bentonite Grout 1. Refer to KEY for explanation of s~bols, codes. abbreviations and definitions. Cl 2. Groundwater level. if indicated above, is for the date specified and may var;. q -3. uses designation is based on visual-manual classification and selected lab testing. .,; PENETRATION RESISTANCE (blows/foot) 'g_ .t. Ham mer Wt. & Drop: 140 lbs I 30 inches <I> 0 0 0 % Fines (<0.075mm) • % Water Content Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF BORING B-3 June 2006 21-1-20442-001 60 ffi 4. The hole location was measured using a cloth tape from existing site features and FIG A-4 ~ should be considered approximate. SHANNON & WILSON, INC. . :,._ ____________________________ ..__Geot __ ""_""'-1'."'-•".""""".--"'-".' =--"""-" _ _. __ s ___ ,_,_o1_, _ _, Total Depth: 10.5 ft. Northing: ____ _ Drilling Method: Hand Boring Hole Diam.: 5in. Top Elevation: __ -~3~2~0~1t~--Easting: _____ _ Drilling Company: Rod Type: Vert. Datum: NAVD88 Station: Drill Rig Equipment: Porlab/e, Hand--0perated Hammer Type: ____ _ ~ Horiz. Datum: ____ _ Offset: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundades between material types, and the trans!lion may be gradual. Very loose, dark brown, silty SAND; moist; (Topsoil) SM. Loose to dense, brown, slightly silty, sandy GRAVEL to silty, gravelly SAND; dry to moist; abundant rootlets to 3.0 feet; (Recessional Outwash) GW-GM/SM. BOTTOM OF BORING COMPLETED 5/16/2006 Other Comments: "" "' 0 " .c .0 a. E 0. E " >, "' 0 (/) CJ) 1.5 2 ~ ~ 3 ~ .§ , 0 ~ • 4 1 0 • • 5 E % • 6 1· • I, 7 10.5 "O ~ "" PENETRATION RESISTANCE (blows/foot) C: " ~ ... Hammer Wt. & Drop: 40 lbs 118 inches ::,- 0"' C!i ~ " 0 40 60 §~--------------"'--_L-----'---'----.L....C----'-,J'---'-'--_;__;,_'--',-'-'---'-'--'--1 0 20 40 60 I 8 ~ % ~ ~ ~ ~ !Ja!,_END Sample Not Recovered I Porter Penetration Test Sample ~ NOTES N 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. w 2. Groundwater level, if indicated above, is for the date specified and may vary. ~ ~ 3. USCS designation is based on visual-manual classification and selected lab testing. Plastic Limit I e I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF HAND BORING HB-1 June 2006 21-1-20442-001 ffi 4. The hole location was measured us;ng a cloth tape from e,;sting site featu,es and SHANNON & WILSON, INC. FIG. A-5 i1.._.s_hou_kl_be_co_n.si.de_,_""_a_p_pro_J<i_ma_t•.· ----------------1..·Geol-·echn-ica-l a•nd_E""""""""--__ taJ_eon_s_"'°_"~ _ _. ______ _, ~ ~ w § I Total Depth: 10.5 ft. Northing: Drilling Method: Hand Boring Hole Diam.: Sin. Top Elevation: -295 ft. Easting: Drilling Company: Rod Type: Vert. Datum: NAVDBB Station: Drill Rig Equipment: Portable, Hand--operated Hammer Type; _____ _ Horiz. Datum: Offset: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. Loose, brown, slightly gravelly to gravelly SAND; moist to wet; abundant organics and wood; (Topsoil) SM. Loose to dense, brown, slightly silty, sandy GRAVEL to silty, gravelly SAND; moist; (Rec,essional Outwash) GW-GM. BOTTOM OF BORING COMPLETED 5/16/2006 Other Comments: = 0 " " .c .Jj a. E a. E "' >, "' 0 (J) (J) 1.5 ' • 0 • 3 ~ §' , " • 4 1 0 • • 5 " z 6 7 10.5 " = PENETRATION RESISTANCE (blows/foot) ~ C: " '5. ... Hammer Wt. & Drop: 40 lbs I 18 inches :, -0"' (j s: " 0 0 20 40 60 ~----------------_L_ _ _L__L _ __,_ ____ _.L_o-'-'-'-'-'---'-c..c.,2"'0----'-----'-'-'4-'-o,'---'---'-----'c..c.,6.,-10 = Sample Not Recovered I Porter Penetration Test Sample NOTES 1. Refer to KEY for explanation of symbols. codes, abbreviations and definitions. 2. Ground\wter level, if indicated above, is for the dale specified and may vary. 3. uses designation is based on visuaknanual classification and selected lab testing. 4. The hole location was measured using a cloth tape from existing site features and should be considered approximate. Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF HAND BORING HB-2 June 2006 21-1-20442-001 SHANNON & WILSON, INC. FIG A 6 Geolect>nioal ,.,. Enwonmental Coos,ltaots • • ____________________ ..._ _________ ..._ ____ .. Total Depth: 7.5 ft. Northing: Drilling Method: Hand Boring Hole Diam.: 5in. Top Elevation: -268 ft. Easting: Drilling Company: Rod Type: Vert. Datum: NAVD88 Station: Drill Rig Equipment: Portable, Hand-operated Hammer Type: _____ _ Horiz. Datum: Offset: Other Comments: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. Loose to medium dense, brown to red-brown, slightly silty to silty, fine SAND, trace of clay; moist; (Outwash) SM/SP-SM. -becomes wet at 6.0 to 7.5 feet BOTTOM OF BORING COMPLETED 5/1612006 LEGEND Sample Not Recovered I Porter Penetration Test Sample l NOTES "" 0 .c .Q E C. >, <I> (/) 0 7.5 N 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. w <, 2. Groundwater level, if indicated above, is for the date specified and may var;. U) <I> 0. E "' (I) 2 3 4 5 0 ...1 3. uses designation is based on visual-manual classification and selected lab testing. ~ :§ " Q ~ ·§ Q ~ • , l 0 ~ 0 z "O ~ C a> :, - 0 "' (9:;: "" PENETRATION RESISTANCE (blows/foot) cg_ " Hammer Wt. & Drop: 40 lbs I 18 inches a> 0 0 21-+-----+------+------I 4 f---"'l,,----+----'--i--'--'-'-------1 8>------+------+------1 10>------+--------l---~-'-'-.I 16>------+------+------1 18<-------+------+-------1 Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton, Washington LOG OF HAND BORING HB-3 June 2006 21-1-20442-001 ffi 4. The ho~ k>cation was measured us;ng a cloth tape from e,;,1;ng s;te features and SHANNON & WILSON, INC. FIG A 7 i._ __ '."°."."'.""-co-ns.;de_red_a_w_,ox_,_m_a_t•.· ----------------.t..-Geot-·echn-""-' '"-'-"°."""'.· -"""-"'.= __ "_11a_,~ _ _. ___ • __ • __ _, ~ Total Depth: 9 ft. Northing: Top Elevation: -220 ft. Easting: Vert. Datum: NAVD88 Station: Horiz. Datum: Offset: SOIL DESCRIPTION Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. Loose to dense. brown. slightly silty, sandy GRAVEL to gravelly SAND; moist; (Alluvium) GW-GM/SM. BOTIOM OF BORING COMPLETED 5/16/2006 Drilling Method: Hand Boring Hole Diam.: Sin. Drilling Company: Rod Type: Drill Rig Equipment: Portable, Hand-operated Hammer Type: ____ _ Other Comments: "' 0 "' 'O ~ "' PENETRATION RESISTANCE (blows/foot) .. ,,:;; .0 ci. C Q) ,,:;;' " Hammer Wt. & Drop: 40 lbs I 18 inches E ::, -C. E 0"' C. >, i!i ~ " if) "' " 0 if) 0 0 20 40 60 • • 2 ~ • 3 ~ 0 ~ C C , 0 • 4 j e ~ ~ 0 • ! 5 0 z • 6 9.0 31--___________ ...J..____L___L_...J.._ __ _.,,. __ -;!;:'--'---'--'-'-'--'-'-f;:--'--"-'-'--'-'-;;::i 0 20 40 60 ~ ~ " ~ ;; w ~ ~ ; LEGEND Sample Not Recovered I Porter Penetration Test Sample NOTES 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. uses designation Js based on visual-manual classification and selected lab testing. 4. The hole location v.ias meaStXed using a cloth tape from existing site features and should be considered approximate. Plastic Limit I • I Liquid Limit Natural Water Content Central Plateau Interceptor Renton. Washington LOG OF BORING HB-4 June 2006 21-1-20442-001 SHANNON & WILSON, INC. FIG A 8 Geotedmical and Environmental Consuttants • • ____________________ ..... _________ ..... ____ .. -~ ..., 9lilJ!j ,_ ~ile: J:\211\20442-001\21-1-20442-001 TPs 1-2.dwg Data: OM17-2006 Author. CNT SHANNON & WILSON, INC. Geotecl'lnical and Environmental Consultants LOG OF TEST PIT TP-1 CD 0 G) © I 'Tl !il )> co SOIL DESCRIPTION Topsoil 1 grass, roots, organics and gravel fill; moist. Very dense, brown to gray, silty, gravelly SAND to silty, sandy GRAVEL; moist; scattered faint iron-oxide staining, cobbles up to 12 inches in diameter; (Fill) GM/SM. Very dense, mottled blueiJray to gray-brown, slightly clayey, silty, gravelly SAND to silty, sandy GRAVEL, trace of clay; moist; scattered, irregular iron-oxide-stained seams; (Fill) SM/GM. Dense, gray-brown, silty, gravelly, SAND; moist; moisture content Increasing with depth to wet at bottom; (Alluvium) SM. NOTE Soil density estimated from difficulty of digging. 'O L C: G) ::,-~~ ¥ I I I I I JOB NO: 21-1-20442-001 DATE: 01-06-2006 LOCATION: W. Side of 154th Pl. SE; PROJECT: Central Plateau Interceptor Inside Bend; Up Hill L-U) ii Sketch of East Pit Side Surface Elevation: Approx. 250 Ft. .l!l C: G) "'.l!l a. i E s: C: Horizontal Distance in Feet 0 <II G) "*' (.) (/J Cl 0 2 4 6 8 10 12 0 2(\ __ _:,C) . : b: --··--·-... ···---:+~--· lcj : • Q. Q ·D··· I • • • ' • -~--------5.8 S-1 CJ i ~ . 0 o Q Co . i <::, : ID . 0. :·o .. 0. 0 O· ·u· .. -:-· .. . . . . 0-' . . . . . ·D· 0 0 4 5.4 S-2 Cl · .'· .. (1° ... :1rp.n .• -\)xiqe-Stained · · · · · · -Seams . · J · : : · :~~:•:·:•:!•::: :::· .. :.~,,~"'""~'*' 'J,,v"' i •0 :Q: i .Qi i 6 10.2 5.3 "~"«,"-·;""'--"''irl'' o· :c:,: Lig~t Seep~ge S4 I 9.9 8,---··- 0 I I . I . · · 9::: · 0--.-: -~1:~-: .-.. \-:-:-l----------- 1 :Ci I I 10,- lo· l a I -0.-·-------, ... .,, ___ .T .. . c:,. ·O 'O .. 10.5 I S-5 I j2 -l File: J:\211\20442-001\21-1-20442-001 TPs 1-2.dwg Date: 06-07-2006 Author: CNT SHANNON & WILSON, INC. Geotechnlcal and Environmental Con1ullante LOG OF TEST PIT TP-2 CD ® 0 0 "Tl !a) ~ .... Q SOIL DESCRIPTION Loose, dark brown, organic topsoil; abundant roots. Loose to medium dense, brown to orange-brown, silty, gravelly SAND to silty, sandy GRAVEL: wet: scattered dark brown organics, iron-oxide staining; (Fill/Alluvium) SM/GM. Soft to medium stiff, light brown, slightly clayey to clayey SILT; wet; abundant decomposed roots; (Fill/Alluvium) ML. Medium dense, gray, silty, gravelly SAND, trace of clay; wet; scattered seams of slightly sandy, slightly clayey silt; cobbles up to 18 by 12 inches: scattered, charred, dark brown organics: scattered iron-oxide-stained seams, harder digging below 1 O feet: (Alluvium) SM/GM. NOTE Soil density estimated from difficulty of digging . "O ~ C Q) :::,- 0"' c'5 ~ ¥ JOB NO: 21-1-20442-001 DATE: 01-06-2006 LOCATION: W. Side of 154th Pl. SE; PROJECT: Central Plateau Interceptor JD Stewart's Driveway ~-j I u:_ 1 Sketch of Q) C -Q) C, I ,= ~g E c. "' Q) ~o Cl) Cl East Pit Side Surface Elevation: Approx. 185 Ft. Horizontal Distance in Feet 4 6 10 12 0, 61.2 I s-1 I 21-:'. "" . ... ·!'-····· ·······-·&··--ci--~~---~- . ' ; . . ,· 33.8 I S-2 22.6 S-3 23.5 S-4 12.B I S-5 4 0.,,: . " 0 ·O· ' • " 0 :.;,$WUf'1f;;./liillJlWi'·?''" ' ® ' 0 0 ' G 0 ® ~ 0 0 0 ·D ., . ., 0 ' Continuous · Moderate Seepage ~lron7Qx!de-Sla!ned~~ i • Jl: : ·• • :-: : • r=~~~~;ide-Stain~ . Seams ..... ; . :tlog(FreshWood)· 6 ·D· i 8 . :..:_:__b .. -1--·· ·o· ! . ' ' O· I .'\" .... I .. 10 --------·----'----· . i 12 (] .. • ' • I ' ' . ' ! . ' • • i • • 0 I • • i • i .... I .. • ' • ' • • i ' • • • ' ' I . . . I . . . . : r.-::-0:::~i : : -.:-. : . c;:, . C) 9· 0 J APPENDIXB GEOTECHNICAL LABORATORY TESTING 21-1-20442-001 I I i' • I l I APPENDIXB GEOTECHNICAL LABORATORY TESTING TABLE OF CONTENTS Page B.l INTRODUCTION ........................................................................................................... B-1 B.2 VISUAL CLASSIFICATION ......................................................................................... B-1 B.3 WATER CONTENT DETERMINATION ..................................................................... B-1 B.4 GRAIN SIZE DISTRIBUTION ...................................................................................... B-1 B.5 ATTERBERG LIMITS DETERMINATION ................................................................. B-2 B.6 REFERENCE .................................................................................................................. B-2 LIST OF FIGURES Figure No. B-1 Grain Size Distribution, Boring B-1 B-2 Grain Size Distribution, Borings B-2 and B-3 B-3 Plasticity Chart, Boring B-1 21-l-20442--001-Rl-AB/wp/LKD 21-1-20442-001 B-i APPENDIXB GEOTECHNICAL LABORATORY TESTING B.1 INTRODUCTION This appendix contains descriptions of the geotechnical laboratory procedures and the results completed on the soil samples obtained from test pits TP-1 and TP-2, and borings B-1, B-2, and B-3. The samples were tested to determine basic index properties to assess engineering characteristics of the site soils. Laboratory testing was completed at the Shannon & Wilson, Inc. laboratory in Seattle, Washington. B.2 VISUAL CLASSIFICATION Soil samples obtained from the explorations were visually classified in the laboratory using a system based on the American Society for Testing and Materials (ASTM) Designation: D 2487, Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System), and ASTM Designation: D 2488, Standard Practice for Description and Identification of Soils (Visual-Manual Procedure). This visual classification allows for convenient and consistent comparison of soils from widespread geographic areas. The laboratory classification is done after completing laboratory index testing and provides a quality control and consistency for the field classification. B.3 WATER CONTENT DETERMINATION Water content determinations were performed in general accordance with ASTM Designation: D 2216, Standard Test Method for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass on all of the retrieved geotechnical soil samples. Water contents are plotted on the boring logs presented in Appendix A. B.4 GRAIN SIZE DISTRIBUTION Grain size analyses were completed on selected samples to determine their grain size distributions. The tests were performed in general accordance with ASTM Designation: D 422, Standard Test Method for Particle-Size Analysis of Soils. Generally, the grain size analyses were completed only on the coarse-grained fraction of the samples. 21-1-20442-001 8-1 The grain size distributions were used to assist in classifying soils and to provide correlations of soil properties. Results of the grain size analyses are plotted as grain size distribution curves presented in Figures B-1 and B-2. A tabulated summary containing the sample depth and description, the natural water content, and the Atterberg Limits (if obtained) is also included on the grain size distribution plots. B.S ATTERBERG LIMITS DETERMINATION Liquid and plastic Atterberg Limits were determined on one selected sample of fine-grained soil obtained from boring B-1 in general accordance with ASTM Designation: D 4318, Standard Test Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. The Atterberg Limits include Liquid Limit (LL), Plastic Limit (PL), and Plasticity Index (PI= LL-PL). The Atterberg Limits are generally used to assist in the classification of soils, indicate soil consistency (when compared with natural water content), and provide correlation to soil properties including compressibility and strength. The results of the Atterberg Limits determination are shown on the boring log for B-1 in Appendix A, and on the plasticity chart in Figure B-3. B.6 REFERENCE American Society for Testing and Materials (ASTM), 2002, Annual Book of Standards, Construction, v. 4.08, Soil and Rock(!): D 420-D 4919: West Conshohocken, Pa. 21-1-20442-001-RI-AB/wp/LKD 21-1-20442-001 B-2 >-I Cl iii ,:: >-00 ll'. w z u: >-z w u 0: w "- BORING ANO SAMPLE NO. e B-1, 5.5 • B-1, S-15 A B-1, S-20 + B.1, S-24 • :::!! G) l OB-1,S-34 l m ' ... SIEVE ANALYSIS S1ZE OF MESH OPENING IN INCHES NO. OF MESH OPENINGS PER INCH, U.S. STANDARD " 8 8 m N -~ ~ ~ "' ~ .... 0 0 0 0 -m .., M N --N • m -N C, 100 ' ' ' ' ' ' ' 90 '' ' ' ' ' ' ' 80 ' ' ' ' ' ' ' ' ' ' ' ' ' ' 70 ' ' ' ' ' ' ' ' ' 60 ' ' ' ' ' ' 50 ' ' ' ' ' ' ----' ' ' 40 -\-' ' ' ' ' ' ' ' ' 30 ' ' ' ' ' 20 10 0 g !! § ~ 8 0 g 0 o m m • N -• M N -"! "' .., M N ., ~ l'l GRAIN SIZE IN MILLIMETERS I COARSE I FINE COARSE MEDIUM FINE COBBLES I GRAVEL SAND DEPTH U.S.C.S. SAMPLE FINES NAT. LL (feet) SYMBOL OESCRIPTION % W.C.% % 22.5 GW Gray-brown, sandy GRAVEL, trace of silt 4.8 10.3 72.5 SM Red-brown. silty, fine SAND 25,7 18.0 97.5 SM Brown, silty, fine SANO, trace of gravel 41.4 20.0 117.5 SM Red-brown, silty, fine SAND, trace of gravel 41.3 17.2 167.5 SM Gray-brown, silty, fine to medium SAND 21.3 13.5 HYDROMETER ANALYSIS GRAIN SIZE IN MILLIMETERS m ~ ~ ~ ~ 8 .., la g/ q ~ 0 10 20 >- 30 I Q w ,:: 40 >-00 ll'. w CJ) ll'. 50 <( 0 ' u >-z 60 w .. u ll'. w -~ "- 70 ---- 80 90 100 .., M N -m § ~ M N ij " " q ~ 8 8 FINES: SILTORCLAY PL Pl Central Plaleau Interceptor Alternatives % % Renton, Washington GRAIN SIZE DISTRIBUTION April 2006 21-1-20442-001 SHANNON & WILSON, INC. I FIG. B-1 G9otechnlcal and En lioi•••lllll Con.ultanb, "Tl ~ OJ ~ >-J: CJ w ;: >-C!l "' w z ii: >-z w 0 "' w "- BORING AND SAMPLE NO. • B-2, S-4 • B-3, S-4 A, B-3, S-9 + B-3, S-14 0 B-3, 5-21 SIEVE ANALYSIS SIZE OF MESH OPENING IN INCHES I NO. OF MESH OPENINGS PER INCH, U.S. STANDARD ~ 8 ~ 8 N -~ ~ ~ ., " 0 0 0 0 -.. • M N M -• .. -100 ' ' ' ' 90 ' ' 80 ' ' ' ' ~ ' ' 70 ' ' ' ' ' ' ' 60 ' ' ' ' ' ' ' ' ' ' ' ' 50 ' ' ' ' ' ' ' ' ' ' ' ' ' 40 ' ' . ' ' ' ' 30 ' ' ' ' . ~ 20 ' ' ' 10 ' 0 i:l 8 8 2 ii! 0 0 0 o m .. • M N -m .. • .., N -m 8 N -• M N -·o GRAIN SIZE IN MILLIMETERS COBBLES COARSE I FINE COARSE MEDIUM FINE I GRAVEL SAND DEPTH U.S.C.S. SAMPLE FINES NAT. LL (feet) SYMBOL DESCRIPTION " W.C.% " 20.0 GP Gray-brown, sandy GRAVEL, trace of silt 2.5 2.5 17.5 SP-SM Gray-brown, slightly silty, gravelly SAND 9.9 9.5 42.5 SM Gray-brown, gravelly, silty SANO 48.3 13.1 67.5 SM Gray-brown, gravelly, silty SAND 31.0 10.0 102.5 SM Red-brown, silty, fine SAND 24.4 21.7 HYDROMETER ANALYSIS GRAIN SIZE IN MILLIMETERS I c; ~ ~ ~ M N 8 q M N 0 0 0 0 " 0 0 10 20 >- 30 J: CJ w ;: 40 >-C!l "' w rJ) 50 "' <( 0 .. 0 . ->-z 60 w ' 0 ' O'. --1 --w "- 70 . 80 90 100 q 1l N -m .. ~ M N 8 " ~ ~ 8 8 8 FINES: SILTORCLAY PL Pl Central Plateau Interceptor Alternatives " " Renton, Washington GRAIN SIZE DISTRIBUTION April 2006 21-1-20442-001 SHANNON & WILSON, INC. I FIG. B-2 Geot.chnlcal -.d lEl,A1oow1MMI Conauitanta .,, !al m w 70 60 50 l a: . X w 40 0 ~ ~ 0 >= (/) .,: 30 _J a.. 20 10 0 0 BORING ANO SAMPLE NO. eB-1,S-18 10 DEPTH (feet) 87.5 CL V V ,, V / V I/ CL-M . MLc rOL /, ,· 20 30 40 50 60 70 LIQUID LIMIT -LL(%) U.S.C.S. SOIL SYMBOL CLASSIFICATION CL Gray, silty CLAY < H / / V / MHc rOH BO 90 100 LL PL Pl NAT. PASS. % .,. % W.C.% #200, % 45 26 19 29.9 / LEGEND CL: Low plasticity inorganic clays; sandy and silty clays CH: High plasticity inorganic clays ML or OL: Inorganic and organic silts and clayey silts of low plasticity MH or OH: Inorganic and organic silts and clayey silts of high plasticity CL-ML: Silty clays and clayey silts 110 Central Plateau Interceptor Alternatives Renton, Washington PLASTICITY CHART April 2006 21-1-20442-001 ~~~~.~~,~~-I FIG. B-3 ~ ~ z ~ ~ N ~ I " r i;, ~ i APPENDIXC GROUNDWATER ANALYTICAL LABORATORY RESULTS 21-1-20442-001 APPENDIXC GROUNDWATER ANALYTICAL LABORATORY RESULTS TABLE OF CONTENTS TABLE Table No. C-1 Groundwater Analytical Results II 2I-1-20442--001-Rl-AClwp/LKD 21-1-20442-001 C-i APPENDIXC GROUNDWATER ANAL YT I CAL LABO RA TORY RES UL TS Groundwater samples were analyzed for contaminants by the following methods: • Petroleum-related hydrocarbons by Method Northwest Total Petroleum Hydrocarbons-Hydrocarbon Identification (NWTPH-HCID) includes gasoline, diesel fuel, and lube oil. • Total metals by U.S. Environmental Protection Agency (EPA) Method 200.8, and dissolved metals by EPA Method 601 OB includes arsenic, barium, cadmium, chromium, copper, lead, manganese, nickel, and zinc • Fecal Coli forms by American Public Health Association (APHA) Standard Method 9222. Samples were submitted under chain of custody to OnSite Environmental, Inc. for chemical analysis of metals and hydrocarbons, and to North Creek Analytical, Inc. for fecal coliforms. Table C-1 in this appendix summarizes groundwater analytical results, followed by the complete analytical laboratory reports. 21-1-20442-001-R l-AC/wp/LKD 21-1-20442-001 C-1 Notes: TABLEC-1 GROUNDWATER ANALYTICAL RESULTS Field Parameter H 7.7 Microbiological 1 Fecal Colifonns ND Petroleum Hydrocarbons 2 Gasoline ND Diesel Fuel ND Lube Oil ND Total Metals' Arsenic 20 Barium 720 Cadmium ND Chromium 64 Copper 120 Lead 57 Manganese 1400 Nickel 64 Zinc 190 Dissolved Metals3 Arsenic ND Barium 28 Cadmium ND Chromium ND Copper ND Lead ND Manganese 51 Nickel ND Zinc ND (I) Units in Colony Forming Units per 100 milliliters (CFU/lOOmL). (2) Units in milligrams per liter (mglL), equivalent to parts per million (ppm). (3) Units in micrograms per liter (uglL), equivalent to parts per billion (ppb). ND -Not Detected 21-1-20442-00 l-Rl-Thl-C-1/wp/edb 21-1-20442-001 GROUNDWATER ANALYTICAL LABORATORY RESULTS 21-1-20442-001 :., On Site Environmental Inc. 14648 NE 951" Street, Redmond, WA 98052 • (425) 883-3881 March 31, 2006 Ted Hopkins Shannon & Wilson, Inc. 400 N 34th Street, Suite 100 Seattle, WA 981 03 Re: Analytical Data for Project 21-1-20442-001 Laboratory Reference No. 0603-159 Dear Ted: Enclosed are the analytical results and associated quality control data for samples submitted on March 20, 2006. Please note that the subcontracted data will follow In the final report. The standard policy of OnSite Environmental Inc. is to store your samples for 30 days from the date of receipt. If you require longer storage, please contact the laboratory. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning the data, or need additional information, please feel free to call me. David Baumeister Project Manager Enclosures OnSite Environmental, Inc. 14648 NE 95'" Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. Date of Report: March 31, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 Case Narrative Samples were collected on March 20, 2006 and received by the laboratory on March 20, 2006. They were maintained at the laboratory at a temperature of 2'C to 6°C except as noted below. 2 General QNQC issues associated with the analytical data enclosed in this laboratory report will be indicated with a reference to a comment or explanation on the Data Qualifier page. More complex and involved QA/QC issues will be discussed in detail below. Total Metals EPA 200.8 Analysis Due to the high concentration of Manganese.in the QC sample, the amount spiked was insufficient for meaningful MS/MSD recovery data. The Spike Blank recovery was 115%. Any other QA/QC issues associated with this extraction and analysis will be indicated with a footnote reference and discussed in detail on the Data Qualifier page. OnSite Environmental, Inc. 14648 NE 95" Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. Date of Report: March 31, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 Date Extracted: Date Analyzed: Matrix: Units: Client ID: Lab ID: Gasoline: POL: Diesel Fuel: POL: Lube Oil: POL: Surrogate Recovery: o-Terphenyl Flags: 3-29-06 3-29-06 Water mg/L (ppm) B-1-GW-1 03-159-01 ND 0.12 ND 0.30 ND 0.49 101% y NWTPH-HCID OnSite Environmental, Inc. 14648 NE 951h Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use al !he individual or company to whom it is addressed. 3 Date of Report: March 31, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 NWTPH-HCID METHOD BLANK QUALITY CONTROL Date Extracted: Date Analyzed: Matrix: Units: Lab ID: Gasoline: POL: Diesel Fuel: POL: Lube Oil: POL: Surrogate Recovery: o-T erphenyl Flags 3-29-06 3-29-06 Water mg/L (ppm) MB0329W1 ND 0.10 ND 0.25 ND 0.40 84°/o y OnSite Environmental, Inc. 14648 NE 95th Street, Redmond, WA 98052 (425) 883-3881 This report pertains lo lhe samples analyzed in accordance wilh lhe chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 4 Date of Report: March 31, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 TOTAL METALS EPA 200.8 Date Extracted: 3-23-06 Date Analyzed: 3-24&27-06 Matrix: Water Units: ug/L (ppb) Lab ID: 03-159-01 Client ID: 8-1-GW-1 /,f-1 t11, Analyte Method Result Arsenic 200.8 20 >' Barium 200.8 720 Cadmium 200.8 ND Chromium 200.8 64 > Sa Copper 200.8 120 Lead 200.8 57 )r5 Manganese 200.8 1400 Nickel 200.8 64 Zinc 200.8 190 OnSite Environmental, Inc. 14648 NE 95'" Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 5 PQL 3.3 56 4.4 11 11 1.1 11 22 56 Date of Report: March 31 • 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 TOTAL METALS EPA 200.8 METHOD BLANK QUALITY CONTROL Date Extracted: Date Analyzed: Matrix: Units: Lab ID: Analyte Arsenic Barium Cadmium Chromium Copper Lead Manganese Nickel Zinc 3-23-06 3-24&27-06 Water ug/L (ppb) MB0323W1 Method 200.8 200.8 200.8 200.8 200.8 200.8 200.8 200.8 200.8 Result ND ND ND ND ND ND ND ND ND OnSite Environmental, Inc. 14648 NE 95~ Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only tor the use of the individual or company to whom it is addressed. 6 POL 3.3 56 4.4 11 11 1.1 11 22 56 Date of Report: March 31, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 TOTAL METALS EPA 200.8 DUPLICATE QUALITY CONTROL Date Extracted: 3-23-06 Date Analyzed: 3-24&27-06 Matrix: Water Units: ug/L (ppb) Lab ID: 03-166-09 Sample Duplicate Analyte Result Result Arsenic 16.9 16.8 Barium 24.4 24.8 Cadmium ND ND Chromium ND ND Copper ND ND Lead 0.493 0.497 Manganese 1060 1070 Nickel ND ND Zinc ND ND RPO POL 0 3.3 56 NA 4.4 NA 11 NA 11 1 1.1 0 11 NA 22 NA 56 OnSite Environmental, Inc. 14648 NE 951" Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use ol the individual or company to whom it is addressed. 7 Flags Date of Report: March 31, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-159 Project: 21-1-20442-001 Date Extracted: 3-23-06 Date Analyzed: 3-24&27-06 Matrix: Water Units: ug/L (ppb) Lab ID: 03-1 66-09 Spike Analyte Level Arsenic 110 Barium 110 Cadmium 110 Chromium 110 Copper 110 Lead 110 Manganese 110 Nickel 110 Zinc 110 TOTAL METALS EPA 200.8 MS/MSD QUALITY CONTROL Percent MS Recovery MSD 124 97 127 133 99 136 110 100 114 106 97 111 107 97 112 109 98 114 1150 79 1210 104 95 113 115 105 118 Percent Recovery RPO 100 3 102 2 103 3 101 4 102 5 103 5 132 5 103 8 107 2 OnSite Environmental, Inc. 14648 NE 95th Street, Redmond, WA 98052 (425) 883-3881 This report pertains 10 the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 8 Flags A ' , OnSite • Environmental Inc. Data Qualifiers and Abbreviations A. Due to a high sample concentration, the amount spiked is insufficient for meaningful MS/MSD recovery data. B • The analyte indicated was also found in the blank sample. C -The duplicate RPD is outside control limits due to high result variability when analyte concentrations are within five times the quantitation limit. E -The value reported exceeds the quantitation range and is an estimate. F. Surrogate recovery data is not available due to the high concentration of coeluting target compounds. G -Insufficient sample quantity for duplicate analysis. H -The analyte indicated is a common laboratory solvent and may have been introduced during sample preparation, and be impacting the sample result. I -Compound recovery is outside of the control limits. J. The value reported was below the practical quantitation limit. The value is an estimate. K. Sample duplicate RPD is outside control limits due to sample inhomogeneity. The sample was re-extracted and re-analyzed with similar results. L • The RPO is outside of the control limits. M. Hydrocarbons in the gasoline range (toluene-napthalene) are present in the sample. O -Hydrocarbons indicative of diesel fuel are present in the sample and are impacting the gasoline result. P -The RPD of the detected concentrations between the two columns is greater than 40. O -Surrogate recovery is outside of the control limits. S -Surrogate recovery data is not available due to the necessary dilution of the sample. T -The sample chromatogram is not similar to a typical ____ _ U -The analyte was analyzed for, but was not detected above the reported sample quantitation limtt. V -Matrix Spike/Matrix Spike Duplicate recoveries are outside control limits due to matrix effects. W -Matrix Spike/Matrix Spike Duplicate RPD are outside control limits due to matrix effects. X -Sample extract treated with a silica gel cleanup procedure. Y -Sample extract treated with an acid/silica gel cleanup procedure. Z- ND -Not Detected at POL POL -Practical Ouantitation Limit RPD -Relative Percent Difference OnSite Environmental, Inc. 14648 NE 95'" Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 9 www.ncalabs.co111 31 March 2006 David Baumeister OnSite Environmental Inc. 14648 NE 95th Street Redmond, WA/USA 98052 RE: NIA Seattle 11720 North Creek Pkwy N, Suite 400, Bothell, WA 98011-8244 42S.420.9200 faK 425.420.9210 Spo«•n• East 11115 Hontoomery, Suite B, Spokane, WA 99206-4776 509.924.9200 faJC 509.924.9290 Portland '3405 SW Nimbus Avenue, Beaverton, OR 97008-7132 503.906.9200 faK 503.906.9210 Bend 203)2 Empl~ Avenue, Suite F-1, Bend, OR 97701-5711 541.363.9310 faJC 541.382.7588 Anchar.1ge 2000 W Jn1em<1Uon;1L Airport Road, Suite A-IO, Ancllorage, Al( 99502-1119 907.563.9200 faJC 907.563.9210 Enclosed are the results of analyses for samples received by the laboratory on 03121106 16:30. If you have any questions concerning this report, please feel free to contact me. Sincerely, Sandra Yakamavich Project Manager ncaTM www.acalabs.com OnSite Environmental Inc. 14648 NE 95th Street Redmond, WA/USA 98052 Seattle 11720 North Creek Pkwy N, Suite 400, Bothell, WA 98011-82411 425.420.9200 l'ax 425.420.9210 Spot,:-11922 E. Ut Avenue, Sl)Okane Valley, WA 99206-5302 S09.92'4.9200 fax 509.924.9290 Portland 9405 SW Nimbus Awnue, Beaverton, OR 97008-7132 503.906.9200 fax SOJ.906.9210 Btlnd 20332 Empire Avenue, Suite F-1, Bend, OR 97701-5711 541.383.9310 fa!f 541.382.7568 AnchM•CI• 2000 W Intemallon;tl Airport !load, Suite A-10, Anchorage, AK 99502-1119 907.563.9200 fax 907.563.9210 Project: NIA Project Number: 21-1-20442-001 Project Manager· David Baumeister Reported: 03/31106 15:25 ANALYTICAL REPORT FOR SAMPLES Sample ID B-1-GW-I North Creek Analytical -Bothell Sandra Y akamavich, Project Manager Laboratory ID Matrix Date Sampltd Date Reteived R6C0505-01 Water 03120/06 I L03 03/21106 16:30 The results in 1h1s report apply IO lhe samples analyzed in accordance with Jhe chain af custody documem. This anoly11cal report mus/ be reproduced in its emirery. North Creek Analyl/cal, Inc. Environmental Laboratory Network Pagel of4 www.acalabs.co111 Seattte 11720 North Crttk f'l,;wy N, Suite 400, Bothell, WA 98011-8244 425.420.9200 fax 425.420.9210 Spok.alHI 11922 E. ht Avenue, Spoki!lne Valley, WA 99206-5302 509.924.9200 fax 509.924.9290 Portl•nd 9405 SW Nimbus Avenue, Beavertof'I, OR 97008-7132 503.906.9200 fax 503.906.9210 Bend 20332 Empire Avenue, Suite F-t, Beod, OR 'H7D1-5711 541.383.9310 fax 541.382.7588 Anchor•go, 2000 W International Airport Road, Suire A-10, Anchorage, AK 99502-1119 907.563.9200 l'ax 907.563.9210 Projec! NIA OnSite Environmental Inc. 14648 NE 95th Street Redmond, WA/USA 98052 Project Number· 21-1-20442-001 P10jec1 ~,,lanago::r: David Baumeister Reported: 03/31/06 15:25 Analyte Microbiological Parameters by APHA Standard Methods North Creek Analytical -Bothell Result Reporting Limi1 Units Dilution Baich Analyzed Method B--1-GW-1 (B6C050S-01)Wattr Sampled: 03n0/0611:03 Received: 03/21/0616:30 Fecal Coliforms ND 10 CflJ/100 ml 6C2401t2 03/21/06 03/24/06 SM 9222 North Creek Analytical -Bothell Sandra Y akamavich, Project Manager The result.r in 1his reporr apply l,i) the samples analyzed in accordance with the chain of custody document. This analytical report must be reproduced in its entirety. North Creek Analyticaf, Inc. Environmental Laboratory Network Notes 1-05, B-01 Page 2 of4 www.ncalabs.com OnSite Environmental Inc. 14648 NE 95th Street Redmond, WA/USA 98052 S.ttle 11720 North Creek Pkwy N, Suite 400. Bothel, WA 98011-8244 425.420.9200 fax 425.420.9210 Spokane 11922 E. 1st Avenue, Spokane Valley, WA 99206-5302 509.924.9200 fax 509.924.9290 Portl1111d 9405 SW Nimbus Avenue, ~averton, OR 97008-7132 503.906.9200 fax 50).906.9210 Bend 20332 Empln!! Avenue, Suite F-1, 8end, OR 97701-5711 541.383.9310 fa~ 541.)82.7588 Anchorage 2000 W Intematlonal Airport Road, Suite A-10, ArlChorage, AK 99502-1119 907 563 9200 fax 907 563 9210 Projec1 NIA Project /'."umber 21-1-20442-00 I Pi oject /\Ianagcr David Baumeister Rtported: 0)/31/0615:25 Microbiological Parameters by APHA Standard Methods· Quality Control North Creek Analytical· Bothell Analyte Result Reporting Limi1 Batch 6C24082: Prepared 03/21/06 Using General Preparation Blank (6C24082-BLKI) Units Spike Level Source Result %REC '%REC Limits RPD RPD Limit Fecal Colifonns ND IO CFU/100 ml North Creek Analytical -Bothell Sandra Y akamavich, Project Manager The re5u/ts /,i lhis report apply 10 1he samples analyzed In accordance with the chain of cusrody d-Ocwnent, This analyt1cal report must be reproduced in tts enr/rety. North Creek Analytical, :Inc. Environmental Laboratory Networlt. Notes Page3 of4 ncaTM www.nc•lab1.co111 OnSite Environmental Inc. 14648 NE 95th Street Redmond, WA/USA 98052 B-0 I Atypical gromh Seattle 11720 North Creek Pl<wy N, Suite 400, Bothell, WA 98011-82'14 425,420.9200 fax 425.420.9210 Spokane 11922 E. 1st Avenue, Spokane Valley, WA 99206-5302 509.92 ... 9200 i'a,c 509.924.9290 Pwtl.nd 9'405 SW Nimbus A-e, Beaverton, OR 97008-7132 soJ.906.9200 rax soJ.906.9210 Bend 20332 Empire A1re11t.1e, Suite F-1, Bend, OR 97701-S7ll 54l.38J.93l0 fax 541.382.7588 Anchor:ii!lle 2000 w Jntematlonal Airport Fl~, Sutte A-10, Anchora,Je, AK 99502-1119 907 563 9200 fax 907 563 9210 Project: N/ A Project Number: 21-1-20442-001 Project Manager: David Baumeister Notes and Definitions Reported: 03131/06 15,25 1-05 Since the sample was out of hold at the time of receipt, the preparationhrn.alysis of the sample could not be initiated within the method-specified hold time. DET Analyte DETECTED ND Analyte NOT DETECTED at or above the reporting limit NR Not Reported dry Sample results reported on a dry weight basis RPO Relative Percent Difference North Creek Analytical -Bothell Sandra Y akamavich, Project Manager The resuhs in 1his report apply to rlre samples analyzed in accordance wirh the chain of cus,ody document. This anolyrical repon mus/ In reproduced tn irs e,mrety. North Cl'ftk Analytical, Inc. En11ironmental Laboratory Nl!twf:Jrlc Page 4 of4 -ot CHAIN OF CUSTODY RECORD Page I al l --- fr-=..... •. 14841 NE 95th strttt, R.clmond, WA 91052 • (.C25) 113-3111 Subcontract laboratory: North Craek Analytical Phone #: ( 425 ) 420 • 9205 Date/Time: 3 ·d-0 -Q(p Contact Pers on: '3,-tod-\a. OSE# Sample ID Date s•mpled .I ~-' -r-1."\-\ ?, -,o-Ol, ~-Rellnq _/ dat~(CX- Compa Ume:/&os; Relinquished bv: data: Company: Ume: Relinquished by: date: Company: Orne: Time Matrix #Jars 1r.oo \\.() l " Received by:-r;;;:;., Companv: NC. A Received by: Company: Received by: Company: ,3(p(.OS-05 Laboratory Reference#: 0' -1 5 9 Project Manager: David Baumeister Project Number: ;ii ~ I-~1. · CO ( Project Name: Ca- Analysis Requested Comments/Special lnstrucUons l er-..-\ (' . 1 ~ L-.. ' &l\.'t. t~ \.\.~.._ r / , '-i Ir r->, ~, data 2Vo(o ~lc..b1~0 {) llme:1<'.o05' data: 5.4 v,fa Ume: date: time: • , OnSite Environmental Inc. 14648 NE 95'" Street, Redmond, WA 98052 • (425) 883-3881 April 10,2006 Ted Hopkins Shannon & Wilson, Inc. 400 N 34th Street, Suite 100 Seattle, WA 98103 Re: Analytical Data for Project 21-1-20442-001 Laboratory Reference No. 0603-159B Dear Ted: Enclosed are the analytical results and associated quality control data for samples submitted on March 20, 2006. The standard policy of OnSite Environmental Inc. is to store your samples for 30 days from the date of receipt. If you require longer storage, please contact the laboratory. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning the data, or need additional information, please feel free to call me. David Baumeister Project Manager Enclosures OnSite Environmental, Inc. 14648 NE 95'" Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody. and is intended only for the use of the individual or company to whom it is addressed. Date of Report: April 10, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-1598 Project: 21-1-20442-001 Case Narrative Samples were collected on March 20, 2006 and received by the laboratory on March 20, 2006. They were maintained at the laboratory at a temperature of 2°C to 6°C except as noted below. 2 General QA/QC issues associated with the analytical data enclosed in this laboratory report will be indicated with a reference to a comment or explanation on the Data Qualifier page. More complex and involved QA/QC issues will be discussed in detail below. OnSite Environmental, Inc. 14648 NE 95~ Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the· samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. Date of Report: April 10, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-1596 Project: 21-1-20442-001 Date Analyzed: 4-6-06 Matrix: Water Units: ug/L (ppb) Lab ID: 03-159-01 Client ID: B-1-GW-1 Analyte Method Arsenic 200.8 Barium 200.8 Cadmium 200.8 Chromium 200.8 Copper 200.8 Lead 200.8 Manganese 200.8 Nickel 200.8 Zinc 200.8 DISSOLVED METALS EPA200.8 Result ND 28 ND ND ND ND 51 ND ND OnSite Environmental, Inc. 14648 NE 95ffi Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 3 POL 3.0 50 4.0 10 10 1.0 10 20 25 Date of Report: April 10, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-1596 Project: 21-1-20442-001 DISSOLVED METALS EPA200.8 METHOD BLANK QUALITY CONTROL Date Analyzed: 4-6-06 Matrix: Units: Lab ID: Analyte Arsenic Barium Cadmium Chromium Copper Lead Manganese Nickel Zinc Water ug/L (ppb) MB0406D2 Method Result 200.8 ND 200.8 ND 200.8 ND 200.8 ND 200.8 ND 200.8 ND 200.8 ND 200.8 ND 200.8 ND OnSite Environmental. Inc. 14648 NE 95~ Street. Redmond. WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 4 PQL 3.0 50 4.0 10 10 1.0 10 20 25 Date of Report: April 10, 2006 Samples Submitted: March 20. 2006 Laboratory Reference: 0603-1598 Project: 21-1-20442-001 DISSOLVED METALS EPA200.8 DUPLICATE QUALITY CONTROL Date Analyzed: Matrix: Units: Lab ID: Analyte Arsenic Barium Cadmium Chromium Copper Lead Manganese Nickel Zinc 4-6-06 Water ug/L (ppb) 03-159-01 Sample Duplicate Result Result ND ND 27.7 28.5 ND ND ND ND ND ND ND ND 50.6 50.7 ND ND ND ND RPO PQL NA 3.0 3 50 NA 4.0 NA 10 NA 10 NA 1.0 0 10 NA 20 NA 25 OnSite Environmental, Inc. 14648 NE 95 1h Street. Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 5 Flags I ' Date of Report April 10, 2006 Samples Submitted: March 20, 2006 Laboratory Reference: 0603-1596 Project: 21-1-20442-001 Date Analyzed: Matrix: Units: Lab ID: Analyte Arsenic Barium Cadmium Chromium Copper Lead Manganese Nickel Zinc 4-6-06 Water ug/L (ppb) 03-159-01 Spike Level 200 200 200 200 200 200 1100 200 200 DISSOLVED METALS EPA200.8 MS/MSD QUALITY CONTROL Percent MS Recovery MSD 209 105 209 230 101 223 197 98 201 194 97 194 198 99 196 200 100 198 240 95 241 194 97 193 207 103 205 Percent Recovery RPD 104 0 98 3 100 2 97 0 98 1 99 1 95 1 96 1 103 1 OnSite Environmental, Inc. 14648 NE g5ffi Street, Redmond, WA 98052 (425) 883-3881 This rePort pertains lo the samples analyzed in accordance with the chain of custody, and is intended only for the use or the individual or company to whom it is addressed. 6 Flags ' .,_ ' , OnSite • Environmental Inc. Data Qualifiers and Abbreviations A -Due to a high sample concentration, the amount spiked is insufficient for meaningful MS/MSD recovery data. B -The analyte indicated was also found in the blank sample. C -The duplicate RPO is outside control limits due to high result variability when analyte concentrations are within five times the quantitation limit. E -The value reported exceeds the quantitation range and is an estimate. F -Surrogate recovery data is not available due to the high concentration of coeluting target compounds. G -Insufficient sample quantity tor duplicate analysis. H -The analyte indicated is a common laboratory solvent and may have been introduced during sample preparation, and be impacting the sample result. I -Compound recovery is outside of the control limits. J -The value reported was below the practical quantitation limit. The value is an estimate. K -Sample duplicate RPO is outside control limits due to sample inhomogeneity. The sample was re-extracted and re-analyzed with similar results. L -The RPO is outside of the control limits. M -Hydrocarbons in the gasoline range (toluene-napthalene) are present in the sample. 0 -Hydrocarbons indicative of diesel fuel are present in the sample and are impacting the gasoline result. P -The RPO of the detected concentrations between the two columns is greater than 40. Q -Surrogate recovery is outside of the control limits. S -Surrogate recovery data is not available due to the necessary dilution of the sample. T -The sample chromatogram is not similar to a typical _____ _ U -The analyte was analyzed for, but was not detected above the reported sample quantitation limit. V -Matrix Spike/Matrix Spike Duplicate recoveries are outside control limits due to matrix effects. W -Matrix Spike/Matrix Spike Duplicate RPO are outside control limits due to matrix effects. X -Sample extract treated with a silica gel cleanup procedure. Y -Sample extract treated with an acid/silica gel cleanup procedure. Z- ND -Not Detected at POL PQL -Practical Quantitation Limit RPO -Relative Percent Difference OnSite Environmental, Inc. 14648 NE 95fu Street, Redmond, WA 98052 (425) 883-3881 This report pertains to the samples analyzed in accordance with the chain of custody, and is intended only for the use of the individual or company to whom it is addressed. 7 ) OnSlta Envll'onmantal Inc. Chain of Custody Page _l_o1 _J_ 14848NE*' BerNI •Aec*nond, WA98052 Pllana: (425) 1183-3881 • Fax: (425) 886-4603 eo..>anys~ Project Number: (C-Ono) 2-l• l•ZA'l"lt.•OO D Same Day 0 1 Day 2;!~~~!.:!~~~-~-Z,~~0 2 Day O 3 Day ~f~"f/"lf ~l(.1",te,rc&('lr,r{ C/'r1 ~ndard CJ wor1<1ng days) l~s-lo --,-----~-- I ~ I I ,- ~i <""e 1l! <ll ~ I I! 11 g 1l! I,~,!,~ 11 ~ e I ... AeoaMldby -tat Mdaw-: ~~ c ... , ~r11 CY, IL/4o As, CJ1 B41f.1 N,, r,,,.., Aellnqwhodby ..._ -Waif' 0,1,\ 'f>iJJO/fl~ /l1&f-A/r AOCOMldby _ ,iJ,J.J 'f/"3/(){,, ~ Aellnqwhod by 0( tfD"""'" -by -by/Date -bylOale Chromatograms with final report D DISTRIBUTION LEGEND: White • Onsi. ~ Yo-. Report ~ Pink • C11on1 ~ SHANNON &WILSON. INC. APPENDIXD RESULTS OF SLOPE STABILITY ANALYSES 21-1-20442-001 .... QJ QJ u. .5 C 0 :;:; (1) > QJ w 400 350 '"'~ 250 200 150 • • • • • • • • • • • • • • Title: Central Plateau lnterceptor;,Section-B-B'; • • • Date: 6/6/2006 • • • • • • • Name: Section e-B' Stati,i;.gsz • • • • • • • Analysis By: MDH Check By: RJG • • • • • • • • • • • • • • • • • • • • • • • • • • Descripfton: Dense to"v dense san~ GRAVEL • wt: 120,. • • • Cohesion: O • • • • • • Phi:40 Description: Very dense silty gravelly SAND Wt: 130 • • • • • • • • • .1.487 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 Cohesion: 0 Phi: 42 Description: Loose to medium dense slightly silty sandy GRAVEL (Colluvium) Wt: 110 Cohesion: 0 Phi: 32 2 Description: Hard silty CLAY Wt: 125 Cohesion: 4000 Phi: 0 400 350 300 Description: Very dense silty fine SAND and hard clayey SIUT Wt: 130 Description: Very dense silty sandy GRAVEL Wt: 135 Cohesion: O Phi:40 6 Cohesion: O Phi: 34 250 200 150 100 100 0 50 100 150 200 250 300 350 400 450 +-' Q) Q) LL. C: C: 0 :;::::; (ti > Q) w 400 350 '- ,oo r 250 200 150 -Title: Central Plateau lnterceptor;"Section "B-B'; • • • Date: 6/6/2006 • • • • • • • Name: Section B-B' Seismic.gsz • • • • • • • Analysis By: MllH • Check By: RJG • • Horiz accel coelf = 0.15g• • • • • • • >.L • • • • • • • • • • • • • • • • • • • • • • • • • Descripfton: Dense to*v dense san~ GRAVEL • Wt: 120. • • • Cohesion: O • • • • • • • • Phi:40 Description: Very dense silty gravelly SAND wt: 130 --. • • • • • • • • • .1.109 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 Cohesion: 0 Phi:42 Description: Loose to medium dense slightly silty sandy GRAVEL (Colluvium) Wt: 110 Cohesion: O Phi: 32 2 Description: Hard silty CLAY Wt: 125 Cohesion: 4000 Phi: 0 cc:-- 400 350 300 Description: Very dense silty fine SAND and hard clayey SIUT Wt: 130 Description: Very dense silty sandy GRAVEL wt: 135 Cohesion: O Phi:40 6 Cohesion: 0 Phi: 34 250 200 150 100 100 0 50 100 150 200 250 300 350 400 450 I SHANNON & WILSON. INC. APPENDIXE IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL REPORT I I 21-1-20442-001 Ill SHANNON & WILSON, INC. Geotechnical and Environmental Consultants Attachment to and part of Report 21-1-20442-001 Date: June 8 2006 To: Roth Hill Engineering Partners, LLC Attn: Mr. Erik Waligorski, P.E. IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL/ENVIRONMENTAL REPORT CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND FOR SPECIFIC CLIENTS. Consultants prepare reports to meet the specific needs of specific individuals. A report prepared for a civil engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consultant prepared your report expressly for you and expressly for the purposes you indicated. No one other than you should apply this report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose other than that originally contemplated without first conferring with the consultant. THE CONSULTANTS REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. Ageotechnical/environmental report is based on a subsurface exploration plan designed to consider a unique set of project-specific factors. Depending on the project, these may include: the general nature of the structure and property involved; its size and configuration; its historical use and practice; the location of the structure on the site and its orientation; other improvements such as access roads, parking Jots, and underground utilities; and the additional risk created by scope-of-service limitations imposed by the client. To help avoid costly problems, ask the consultant to evaluate how any factors that change subsequent to the date of the report may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used: (I) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); (2) when the size, elevation, or configuration of the proposed project is altered; (3) when the location or orientation of the proposed project is modified; (4) when there is a change of ownership; or (5) for application to an adjacent site. Consultants cannot accept responsibility for problems that may occur if they are not consulted after factors which were considered in the development of the report have changed. SUBSURFACE CONDITIONS CAN CHANGE. Subsurface conditions may be affected as a result of natural processes or human activity. Because a geotechnicaVenvironmental report is based on conditions that existed at the time of subsurface exploration, construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the consultant to advise if additional tests are desirable before construction starts; for example, groundwater conditions commonly vary seasonally. , Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnical/environmental report. The consultant should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS. Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions in areas not sampled may differ from those predicted in your report. While nothing can be done to prevent such situations, you and your consultant can work together to help , reduce their impacts. Retaining your consultant to observe subsurface construction operations can be particularly beneficial in this respect. Page I of2 1/2006 • ' A REPORT'S CONCLUSIONS ARE PRELIMINARY. The conclusions contained in your consultant1s report arc preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar with the background information needed to determine whether or not the report's recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant who developed your report cannot assume responsibility or liability for the adequacy of the report's recommendations if another party is retained to observe construction. THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnical/environmental report. To help avoid these problems, the consultant should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydrogeological, and environmental findings, and to review the adequacy of their plans and specifications relative to these issues. BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE REPORT. Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnical/environmental reports. These final logs should not, under any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/enviromnental report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared, and that developing construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because geotechnical/enviromnental engineering is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in their contracts, reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the consultant's liabilities to other parties; rather, they are definitive clauses that identifywbere the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions. The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland Page 2 of2 1/2006